WorldWideScience

Sample records for single transition state

  1. Fast Step Transition and State Identification (STaSI) for Discrete Single-Molecule Data Analysis.

    Science.gov (United States)

    Shuang, Bo; Cooper, David; Taylor, J Nick; Kisley, Lydia; Chen, Jixin; Wang, Wenxiao; Li, Chun Biu; Komatsuzaki, Tamiki; Landes, Christy F

    2014-09-18

    We introduce a step transition and state identification (STaSI) method for piecewise constant single-molecule data with a newly derived minimum description length equation as the objective function. We detect the step transitions using the Student's t test and group the segments into states by hierarchical clustering. The optimum number of states is determined based on the minimum description length equation. This method provides comprehensive, objective analysis of multiple traces requiring few user inputs about the underlying physical models and is faster and more precise in determining the number of states than established and cutting-edge methods for single-molecule data analysis. Perhaps most importantly, the method does not require either time-tagged photon counting or photon counting in general and thus can be applied to a broad range of experimental setups and analytes.

  2. Single-ended transition state finding with the growing string method.

    Science.gov (United States)

    Zimmerman, Paul M

    2015-04-05

    Reaction path finding and transition state (TS) searching are important tasks in computational chemistry. Methods that seek to optimize an evenly distributed set of structures to represent a chemical reaction path are known as double-ended string methods. Such methods can be highly reliable because the endpoints of the string are fixed, which effectively lowers the dimensionality of the reaction path search. String methods, however, require that the reactant and product structures are known beforehand, which limits their ability for systematic exploration of reactive steps. In this article, a single-ended growing string method (GSM) is introduced which allows for reaction path searches starting from a single structure. The method works by sequentially adding nodes along coordinates that drive bonds, angles, and/or torsions to a desired reactive outcome. After the string is grown and an approximate reaction path through the TS is found, string optimization commences and the exact TS is located along with the reaction path. Fast convergence of the string is achieved through use of internal coordinates and eigenvector optimization schemes combined with Hessian estimates. Comparison to the double-ended GSM shows that single-ended method can be even more computationally efficient than the already rapid double-ended method. Examples, including transition metal reactivity and a systematic, automated search for unknown reactivity, demonstrate the efficacy of the new method. This automated reaction search is able to find 165 reaction paths from 333 searches for the reaction of NH3 BH3 and (LiH)4 , all without guidance from user intuition. © 2015 Wiley Periodicals, Inc.

  3. Electrical manipulation of spin states in a single electrostatically gated transition-metal complex

    DEFF Research Database (Denmark)

    Osorio, Edgar A; Moth-Poulsen, Kasper; van der Zant, Herre S J

    2010-01-01

    We demonstrate an electrically controlled high-spin (S = 5/2) to low-spin (S = 1/2) transition in a three-terminal device incorporating a single Mn(2+) ion coordinated by two terpyridine ligands. By adjusting the gate-voltage we reduce the terpyridine moiety and thereby strengthen the ligand......-field on the Mn-atom. Adding a single electron thus stabilizes the low-spin configuration and the corresponding sequential tunnelling current is suppressed by spin-blockade. From low-temperature inelastic cotunneling spectroscopy, we infer the magnetic excitation spectrum of the molecule and uncover also...... a strongly gate-dependent singlet-triplet splitting on the low-spin side. The measured bias-spectroscopy is shown to be consistent with an exact diagonalization of the Mn-complex, and an interpretation of the data is given in terms of a simplified effective model....

  4. Variational Transition State Theory

    Energy Technology Data Exchange (ETDEWEB)

    Truhlar, Donald G. [Univ. of Minnesota, Minneapolis, MN (United States)

    2016-09-29

    This is the final report on a project involving the development and applications of variational transition state theory. This project involved the development of variational transition state theory for gas-phase reactions, including optimized multidimensional tunneling contributions and the application of this theory to gas-phase reactions with a special emphasis on developing reaction rate theory in directions that are important for applications to combustion. The development of variational transition state theory with optimized multidimensional tunneling as a useful computational tool for combustion kinetics involved eight objectives.

  5. Variational transition state theory

    Energy Technology Data Exchange (ETDEWEB)

    Truhlar, D.G. [Univ. of Minnesota, Minneapolis (United States)

    1993-12-01

    This research program involves the development of variational transition state theory (VTST) and semiclassical tunneling methods for the calculation of gas-phase reaction rates and selected applications. The applications are selected for their fundamental interest and/or their relevance to combustion.

  6. Variational transition state theory

    International Nuclear Information System (INIS)

    Truhlar, D.G.

    1986-01-01

    This project is concerned with the development and applications of generalized transition state theory and multidimensional tunneling approximations to chemical reaction rates. They have developed and implemented several practical versions of variational transition state theory (VTST), namely canonical variational theory (CVT), improved canonical variational theory (ICVT), and microcanonical variational theory (μVT). They have also developed and implemented several accurate multidimensional semiclassical tunneling approximations, the most accurate of which are the small-curvature semiclassical adiabatic (SCSA), large-curvature version-3 (LC3), and least-action (LA) approximations. They have applied the methods to thermal rate constants, using transmission coefficients based on ground-state tunneling, and they have also presented and applied adiabatic and diabatic extensions to calculated rate constants for vibrationally excited reactants. Their general goal is to develop accurate methods for calculating chemical reaction rate constants that remain practical even for reasonably complicated molecules. The approximations mentioned above yield rate constants for systems whose potential energy surface is known or assumed. Thus a second, equally important aspect of their work is the determination or modeling, semi-empirically and/or from electronic structure calculations, of potential energy surfaces

  7. Visualizing cell state transition using Raman spectroscopy.

    Directory of Open Access Journals (Sweden)

    Taro Ichimura

    Full Text Available System level understanding of the cell requires detailed description of the cell state, which is often characterized by the expression levels of proteins. However, understanding the cell state requires comprehensive information of the cell, which is usually obtained from a large number of cells and their disruption. In this study, we used Raman spectroscopy, which can report changes in the cell state without introducing any label, as a non-invasive method with single cell capability. Significant differences in Raman spectra were observed at the levels of both the cytosol and nucleus in different cell-lines from mouse, indicating that Raman spectra reflect differences in the cell state. Difference in cell state was observed before and after the induction of differentiation in neuroblastoma and adipocytes, showing that Raman spectra can detect subtle changes in the cell state. Cell state transitions during embryonic stem cell (ESC differentiation were visualized when Raman spectroscopy was coupled with principal component analysis (PCA, which showed gradual transition in the cell states during differentiation. Detailed analysis showed that the diversity between cells are large in undifferentiated ESC and in mesenchymal stem cells compared with terminally differentiated cells, implying that the cell state in stem cells stochastically fluctuates during the self-renewal process. The present study strongly indicates that Raman spectral morphology, in combination with PCA, can be used to establish cells' fingerprints, which can be useful for distinguishing and identifying different cellular states.

  8. Coherent properties of single quantum dot transitions and single photon emission

    Energy Technology Data Exchange (ETDEWEB)

    Ester, Patrick

    2008-04-23

    In this work, the properties and the different dephasing mechanisms of single QD transitions are analyzed. In addition, some applications are presented which arise due to the properties of the confined exciton. The isolation of a single QD out of the ensemble is achieved via near field shadow masks, which restricts excitation and QD luminescence to a single QD. The integration of a QD-layer into a diode structure allows for an analysis of various dephasing mechanisms of a confined electron hole pair. The single QD is characterized regarding the energy of nearly all possible transitions, e.g. the ground state, excited states, charged states, multiple occupations, and phonon assisted absorptions. A very important issue in this content is the voltage dependence of the transition energy and thereby the ability of tunneling processes of charge carriers in and out of the QD. The QD-states, which are subject of investigation here, are the single exciton ground state, the first excited state (p-shell), and the (GaAs-) LO (longitudinal optical) phonon assisted absorption. By applying a suitable voltage, the resonantly excited ground state exciton is able to decay by a tunneling process, which reflects the transition energy in the photocurrent spectra. The p-shell transition decays by a relaxation process into the ground state, followed by an optical recombination process. The phonon assisted absorption differs from the p-shell transition. The resonant excitation energy fits to the exciton ground state energy plus the energy of a GaAs LO phonon. In this case, the single exciton (ground state) is generated as well as a GaAs LO phonon. These three states are investigated in different respects, such as different applied voltages, excitation polarizations, excitation intensities, and coherent properties. The LO-assisted absorption shows also a saturation behavior. The exciton in the QD is able to interfere with the second laser pulse due to the storage of the phase information

  9. Transition paths in single-molecule force spectroscopy.

    Science.gov (United States)

    Cossio, Pilar; Hummer, Gerhard; Szabo, Attila

    2018-03-28

    In a typical single-molecule force spectroscopy experiment, the ends of the molecule of interest are connected by long polymer linkers to a pair of mesoscopic beads trapped in the focus of two laser beams. At constant force load, the total extension, i.e., the end-to-end distance of the molecule plus linkers, is measured as a function of time. In the simplest systems, the measured extension fluctuates about two values characteristic of folded and unfolded states, with occasional transitions between them. We have recently shown that molecular (un)folding rates can be recovered from such trajectories, with a small linker correction, as long as the characteristic time of the bead fluctuations is shorter than the residence time in the unfolded (folded) state. Here, we show that accurate measurements of the molecular transition path times require an even faster apparatus response. Transition paths, the trajectory segments in which the molecule (un)folds, are properly resolved only if the beads fluctuate more rapidly than the end-to-end distance of the molecule. Therefore, over a wide regime, the measured rates may be meaningful but not the transition path times. Analytic expressions for the measured mean transition path times are obtained for systems diffusing anisotropically on a two-dimensional free energy surface. The transition path times depend on the properties both of the molecule and of the pulling device.

  10. State Transitions in Semiarid Landscapes

    Science.gov (United States)

    Phillips, J. D.

    2012-04-01

    The U.S. Department of Agriculture has developed a large number of state-and-transition models (STM) to predict and interpret changes in vegetation communities in drylands of the southwestern U.S. These are represented as box-and-arrow models indicating potential changes in response to various combinations of management practices and environmental forcings. Analysis of the 320 STMs developed for areas within the state of Texas reveals two important aspects of environmental change in semiarid environments. First, the STMs are highly local—they are specific to very particular combinations of landform, soil, and climate. This is consistent with the perfect landscape concept in geomorphology, which emphasizes the irreducible importance of geographically and historically contingent local factors in addition to universal laws or principles in determining the state or condition of landscapes. Second, analysis of the STMs using algebraic graph theory shows that a majority of them have structures that tend to amplify effects of change and disturbances. In many cases the STMs represent a form of self-organization characterized by the potential of divergent behavior rather than convergence toward a dominant pattern or outcome. These results indicate that geomorphic, hydrologic, and ecological responses to climate and land use change are likely to be highly variable and idiosyncratic, both within and between semiarid landscapes of Texas.

  11. Transitioning from a single-site pilot project to a state-wide regional telehealth service: The experience from the Victorian Stroke Telemedicine programme.

    Science.gov (United States)

    Bagot, Kathleen L; Cadilhac, Dominique A; Kim, Joosup; Vu, Michelle; Savage, Mark; Bolitho, Les; Howlett, Glenn; Rabl, Justin; Dewey, Helen M; Hand, Peter J; Denisenko, Sonia; Donnan, Geoffrey A; Bladin, Christopher F

    2017-12-01

    Scaling of projects from inception to establishment within the healthcare system is rarely formally reported. The Victorian Stroke Telemedicine (VST) programme provided a very useful opportunity to describe how rural hospitals in Victoria were able to access a network of Melbourne-based neurologists via telemedicine. The VST programme was initially piloted at one site in 2010 and has gradually expanded as a state-wide regional service operating with 16 hospitals in 2017. The aim of this paper is to summarise the factors that facilitated the state-wide transition of the VST programme. A naturalistic case-study was used and data were obtained from programme documents, e.g. minutes of governance committees, including the steering committee, the management committee and six working groups; operational and evaluation documentation, interviews and research field-notes taken by project staff. Thematic analysis was undertaken, with results presented in narrative form to provide a summary of the lived experience of developing and scaling the VST programme. The main success factors were attaining funding from various sources, identifying a clinical need and evidence-based solution, engaging stakeholders and facilitating co-design, including embedding the programme within policy, iterative evaluation including performing financial sustainability modelling, and conducting dissemination activities of the interim results, including promotion of early successes.

  12. Dependency in State Transitions of Wind Turbines

    DEFF Research Database (Denmark)

    Herp, Jürgen; Ramezani, Mohammad Hossein; S. Nadimi, Esmaeil

    2017-01-01

    © 2017 IEEE. Turbine states and predicting the transition into failure states ahead of time is important in operation and maintenance of wind turbines. This study presents a method to monitor state transitions of a wind turbine based on the online inference on residuals. In a Bayesian framework...... the impact machine learning concepts have on the predictive performance of the presented models. In conclusion, a study on model residuals is performed to highlight the contribution to wind turbine monitoring. The presented algorithm can consistently detect the state transition under various configurations...

  13. Bifurcations of transition states: Morse bifurcations

    International Nuclear Information System (INIS)

    MacKay, R S; Strub, D C

    2014-01-01

    A transition state for a Hamiltonian system is a closed, invariant, oriented, codimension-2 submanifold of an energy level that can be spanned by two compact codimension-1 surfaces of unidirectional flux whose union, called a dividing surface, locally separates the energy level into two components and has no local recrossings. For this to happen robustly to all smooth perturbations, the transition state must be normally hyperbolic. The dividing surface then has locally minimal geometric flux through it, giving an upper bound on the rate of transport in either direction. Transition states diffeomorphic to S 2m−3 are known to exist for energies just above any index-1 critical point of a Hamiltonian of m degrees of freedom, with dividing surfaces S 2m−2 . The question addressed here is what qualitative changes in the transition state, and consequently the dividing surface, may occur as the energy or other parameters are varied? We find that there is a class of systems for which the transition state becomes singular and then regains normal hyperbolicity with a change in diffeomorphism class. These are Morse bifurcations. Various examples are considered. Firstly, some simple examples in which transition states connect or disconnect, and the dividing surface may become a torus or other. Then, we show how sequences of Morse bifurcations producing various interesting forms of transition state and dividing surface are present in reacting systems, by considering a hypothetical class of bimolecular reactions in gas phase. (paper)

  14. Transitions between compound states of spherical nuclei

    International Nuclear Information System (INIS)

    Kadmenskii, S.G.; Markushev, V.P.; Furman, V.I.

    1980-01-01

    Wigner's statistical matrices are used to study the average reduced g widths and their dispersion for g transitions from a compound state c to another state f, with a lower excitation energy but of arbitrary complexity, for spherical nuclei. It is found that the Porter--Thomas distribution holds for the g widths for all cases of practical interest. In g transitions between compound states c and c' with E/sub g/< or =2 MeV, the most important transitions are M1 transitions involving the major many-quasiparticle components of state c and E1 transitions involving the minor components of state c. It is shown that the strength functions predicted by the various theories for M1 and E1 transitions between compound states with E/sub g/< or =2 MeV are similar. Preference is assigned to the M1-transition version because of experimental results on (n,ga) reactions with thermal and resonance neutrons

  15. Density of states and spatially inhomogeneous conductance near the metal-insulator transition in Pr{sub 0.68}Pb{sub 0.32}MnO{sub 3} single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Wirth, S; Roessler, Sahana; Ernst, S; Steglich, F [Max Planck Institute for Chemical Physics of Solids, Noethnitzer Strasse 40, 01187 Dresden (Germany); Padmanabhan, B; Bhat, H L; Elizabeth, Suja [Department of Physics, Indian Institute of Science, Bangalore 560012 (India)

    2008-10-29

    Single crystals of Pr{sub 0.68}Pb{sub 0.32}MnO{sub 3} have been investigated by scanning tunneling microscopy over a broad temperature range. In this material, a distinct separation of the ferromagnetic and the metal-insulator transition temperature, T{sub C}{approx}210 K and T{sub MI}{approx}255 K, respectively, was observed. Spectroscopic tunneling studies revealed that even on a local scale the system switches from predominantly metallic to insulating within a narrow temperature range around T{sub MI}. Inhomogeneities of the zero-bias conductance with small patches of metallic clusters on a length scale of 2-3 nm, however, were only observed within the temperature range T{sub C}state, but homogeneous ferromagnetic and insulating states.

  16. Auger transitions in singly and multiply ionized atoms

    International Nuclear Information System (INIS)

    Mehlhorn, W.

    1978-01-01

    Some recent progress in Auger and autoionizing electron spectrometry of free metal atoms and of multiply ionized atoms is reviewed. The differences which arise between the spectra of atoms in the gaseous and the solid state are due to solid state effects. This will be shown for Cd as an example. The super Coster-Kronig transitions 3p-3d 2 (hole notation) and Coster-Kronig transitions 3p-3d 4s have been measured and compared with free-atom calculations for free Zn atoms. The experimental width GAMMA(3p)=(2.1+-0.2)eV found for the free atom agrees with the value obtained for solid Zn but is considerably smaller than the theoretical value for the free atom. Autoionizing spectra of Na following an L-shell excitation or ionization by different particles are compared and discussed. The nonisotropic angular distribution of electrons from the transition 2p 5 3s 2 2 Psub(3/2)→2p 6 +e - is compared with theoretical calculations. Two examples for Auger spectrometry of multiply ionized atoms are given: (1) excitation of neon target atoms by light and heavy ions, and (2) excitation of projectile ions Be + and B + in single gas collisions with CH 4 . A strong alignment of the excited atoms has also been found here

  17. Roflumilast - A reversible single-crystal to single-crystal phase transition at 50 °C

    Science.gov (United States)

    Viertelhaus, Martin; Holst, Hans Christof; Volz, Jürgen; Hummel, Rolf-Peter

    2013-01-01

    Roflumilast is a selective phosphodiesterase type 4 inhibitor and is marketed under the brand names Daxas®, Daliresp® and Libertec®. A phase transition of the drug substance roflumilast was observed at 50 °C. The low temperature form, the high temperature form and the phase transition were characterised by differential scanning calorimetry, variable temperature powder X-ray diffraction and single crystal X-ray diffraction, Raman spectroscopy and solid state NMR spectroscopy. The phase transition of roflumilast at 50 °C is completely reversible, the high temperature form cannot be stabilised by quench cooling and the phase transition does not influence the quality of the active pharmaceutical ingredient (API) and the drug product. It was observed to be a single crystal to single crystal phase transition.

  18. Single-layer transition metal sulfide catalysts

    Science.gov (United States)

    Thoma, Steven G [Albuquerque, NM

    2011-05-31

    Transition Metal Sulfides (TMS), such as molybdenum disulfide (MoS.sub.2), are the petroleum industry's "workhorse" catalysts for upgrading heavy petroleum feedstocks and removing sulfur, nitrogen and other pollutants from fuels. We have developed an improved synthesis technique to produce SLTMS catalysts, such as molybdenum disulfide, with potentially greater activity and specificity than those currently available. Applications for this technology include heavy feed upgrading, in-situ catalysis, bio-fuel conversion and coal liquefaction.

  19. Unconventional phase transitions in a constrained single polymer chain

    International Nuclear Information System (INIS)

    Klushin, L I; Skvortsov, A M

    2011-01-01

    Phase transitions were recognized among the most fascinating phenomena in physics. Exactly solved models are especially important in the theory of phase transitions. A number of exactly solved models of phase transitions in a single polymer chain are discussed in this review. These are three models demonstrating the second order phase transitions with some unusual features: two-dimensional model of β-structure formation, the model of coil–globule transition and adsorption of a polymer chain grafted on the solid surface. We also discuss models with first order phase transitions in a single macromolecule which admit not only exact analytical solutions for the partition function with explicit finite-size effects but also the non-equilibrium free energy as a function of the order parameter (Landau function) in closed analytical form. One of them is a model of mechanical desorption of a macromolecule, which demonstrates an unusual first order phase transition with phase coexistence within a single chain. Features of first and second order transitions become mixed here due to phase coexistence which is not accompanied by additional interfacial free energy. Apart from that, there exist several single-chain models belonging to the same class (adsorption of a polymer chain tethered near the solid surface or liquid–liquid interface, and escape transition upon compressing a polymer between small pistons) that represent examples of a highly unconventional first order phase transition with several inter-related unusual features: no simultaneous phase coexistence, and hence no phase boundary, non-concave thermodynamic potential and non-equivalence of conjugate ensembles. An analysis of complex zeros of partition functions upon approaching the thermodynamic limit is presented for models with and without phase coexistence. (topical review)

  20. Factorised steady states and condensation transitions in ...

    Indian Academy of Sciences (India)

    I will then consider a more general class of mass trans- port models, encompassing continuous mass variables and discrete time updating, and present a necessary and sufficient condition for the steady state to factorise. The prop- erty of factorisation again allows an analysis of the condensation transitions which may occur.

  1. Transition state theory for enzyme kinetics

    Science.gov (United States)

    Truhlar, Donald G.

    2015-01-01

    This article is an essay that discusses the concepts underlying the application of modern transition state theory to reactions in enzymes. Issues covered include the potential of mean force, the quantization of vibrations, the free energy of activation, and transmission coefficients to account for nonequilibrium effect, recrossing, and tunneling. PMID:26008760

  2. Kinetic analysis of single molecule FRET transitions without trajectories

    Science.gov (United States)

    Schrangl, Lukas; Göhring, Janett; Schütz, Gerhard J.

    2018-03-01

    Single molecule Förster resonance energy transfer (smFRET) is a popular tool to study biological systems that undergo topological transitions on the nanometer scale. smFRET experiments typically require recording of long smFRET trajectories and subsequent statistical analysis to extract parameters such as the states' lifetimes. Alternatively, analysis of probability distributions exploits the shapes of smFRET distributions at well chosen exposure times and hence works without the acquisition of time traces. Here, we describe a variant that utilizes statistical tests to compare experimental datasets with Monte Carlo simulations. For a given model, parameters are varied to cover the full realistic parameter space. As output, the method yields p-values which quantify the likelihood for each parameter setting to be consistent with the experimental data. The method provides suitable results even if the actual lifetimes differ by an order of magnitude. We also demonstrated the robustness of the method to inaccurately determine input parameters. As proof of concept, the new method was applied to the determination of transition rate constants for Holliday junctions.

  3. A Model of Mental State Transition Network

    Science.gov (United States)

    Xiang, Hua; Jiang, Peilin; Xiao, Shuang; Ren, Fuji; Kuroiwa, Shingo

    Emotion is one of the most essential and basic attributes of human intelligence. Current AI (Artificial Intelligence) research is concentrating on physical components of emotion, rarely is it carried out from the view of psychology directly(1). Study on the model of artificial psychology is the first step in the development of human-computer interaction. As affective computing remains unpredictable, creating a reasonable mental model becomes the primary task for building a hybrid system. A pragmatic mental model is also the fundament of some key topics such as recognition and synthesis of emotions. In this paper a Mental State Transition Network Model(2) is proposed to detect human emotions. By a series of psychological experiments, we present a new way to predict coming human's emotions depending on the various current emotional states under various stimuli. Besides, people in different genders and characters are taken into consideration in our investigation. According to the psychological experiments data derived from 200 questionnaires, a Mental State Transition Network Model for describing the transitions in distribution among the emotions and relationships between internal mental situations and external are concluded. Further more the coefficients of the mental transition network model were achieved. Comparing seven relative evaluating experiments, an average precision rate of 0.843 is achieved using a set of samples for the proposed model.

  4. Coherent excitation of a single atom to a Rydberg state

    DEFF Research Database (Denmark)

    Miroshnychenko, Yevhen; Gaëtan, Alpha; Evellin, Charles

    2010-01-01

    We present the coherent excitation of a single Rubidium atom to the Rydberg state 58d3/2 using a two-photon transition. The experimental setup is described in detail, as are experimental techniques and procedures. The coherence of the excitation is revealed by observing Rabi oscillations between...

  5. Novel doping alternatives for single-layer transition metal dichalcogenides

    Science.gov (United States)

    Onofrio, Nicolas; Guzman, David; Strachan, Alejandro

    2017-11-01

    Successful doping of single-layer transition metal dichalcogenides (TMDs) remains a formidable barrier to their incorporation into a range of technologies. We use density functional theory to study doping of molybdenum and tungsten dichalcogenides with a large fraction of the periodic table. An automated analysis of the energetics, atomic and electronic structure of thousands of calculations results in insightful trends across the periodic table and points out promising dopants to be pursued experimentally. Beyond previously studied cases, our predictions suggest promising substitutional dopants that result in p-type transport and reveal interesting physics behind the substitution of the metal site. Doping with early transition metals (TMs) leads to tensile strain and a significant reduction in the bandgap. The bandgap increases and strain is reduced as the d-states are filled into the mid TMs; these trends reverse as we move into the late TMs. Additionally, the Fermi energy increases monotonously as the d-shell is filled from the early to mid TMs and we observe few to no gap states, indicating the possibility of both p- (early TMs) and n- (mid TMs) type doping. Quite surprisingly, the simulations indicate the possibility of interstitial doping of TMDs; the energetics reveal that a significant number of dopants, increasing in number from molybdenum disulfide to diselenide and to ditelluride, favor the interstitial sites over adsorbed ones. Furthermore, calculations of the activation energy associated with capturing the dopants into the interstitial site indicate that the process is kinetically possible. This suggests that interstitial impurities in TMDs are more common than thought to date and we propose a series of potential interstitial dopants for TMDs relevant for application in nanoelectronics based on a detailed analysis of the predicted electronic structures.

  6. Transition-state theory and dynamical corrections

    DEFF Research Database (Denmark)

    Henriksen, Niels Engholm; Hansen, Flemming Yssing

    2002-01-01

    . The correction factor due to non-adiabatic dynamics is considered in relation to the non-activated dissociative sticking of N-2 on Fe(111). For this process, conventional transition-state theory gives a sticking probability which is about 10 times too large (at T = 300 K). We estimate that the sticking......We consider conventional transition-state theory, and show how quantum dynamical correction factors can be incorporated in a simple fashion, as a natural extension of the fundamental formulation. Corrections due to tunneling and non-adiabatic dynamics are discussed, with emphasis on the latter...... probability is reduced by a factor of 2 due to non-adiabatic dynamics....

  7. Quantum phase transitions in matrix product states

    International Nuclear Information System (INIS)

    Zhu Jingmin

    2008-01-01

    We present a new general and much simpler scheme to construct various quantum phase transitions (QPTs) in spin chain systems with matrix product ground states. By use of the scheme we take into account one kind of matrix product state (MPS) QPT and provide a concrete model. We also study the properties of the concrete example and show that a kind of QPT appears, accompanied by the appearance of the discontinuity of the parity absent block physical observable, diverging correlation length only for the parity absent block operator, and other properties which are that the fixed point of the transition point is an isolated intermediate-coupling fixed point of renormalization flow and the entanglement entropy of a half-infinite chain is discontinuous. (authors)

  8. Quantum Phase Transitions in Matrix Product States

    International Nuclear Information System (INIS)

    Jing-Min, Zhu

    2008-01-01

    We present a new general and much simpler scheme to construct various quantum phase transitions (QPTs) in spin chain systems with matrix product ground states. By use of the scheme we take into account one kind of matrix product state (MPS) QPT and provide a concrete model. We also study the properties of the concrete example and show that a kind of QPT appears, accompanied by the appearance of the discontinuity of the parity absent block physical observable, diverging correlation length only for the parity absent block operator, and other properties which are that the fixed point of the transition point is an isolated intermediate-coupling fixed point of renormalization flow and the entanglement entropy of a half-infinite chain is discontinuous

  9. State-transition diagrams for biologists.

    Directory of Open Access Journals (Sweden)

    Hugues Bersini

    Full Text Available It is clearly in the tradition of biologists to conceptualize the dynamical evolution of biological systems in terms of state-transitions of biological objects. This paper is mainly concerned with (but obviously not limited too the immunological branch of biology and shows how the adoption of UML (Unified Modeling Language state-transition diagrams can ease the modeling, the understanding, the coding, the manipulation or the documentation of population-based immune software model generally defined as a set of ordinary differential equations (ODE, describing the evolution in time of populations of various biological objects. Moreover, that same UML adoption naturally entails a far from negligible representational economy since one graphical item of the diagram might have to be repeated in various places of the mathematical model. First, the main graphical elements of the UML state-transition diagram and how they can be mapped onto a corresponding ODE mathematical model are presented. Then, two already published immune models of thymocyte behavior and time evolution in the thymus, the first one originally conceived as an ODE population-based model whereas the second one as an agent-based one, are refactored and expressed in a state-transition form so as to make them much easier to understand and their respective code easier to access, to modify and run. As an illustrative proof, for any immunologist, it should be possible to understand faithfully enough what the two software models are supposed to reproduce and how they execute with no need to plunge into the Java or Fortran lines.

  10. Saha equation, single and two particle states

    Science.gov (United States)

    Kraeft, W. D.; Girardeau, M. D.; Strege, B.

    1990-01-01

    Single- and two-particle properties in a dense plasma are discussed in connection with their role in the mass action law for a partially ionized plasma. The two-particle-bound states are nearly density independent, while the continuum is essentially shifted. The single-particle states are damped, and their energy has a negative shift and a parabolic behavior for small momenta.

  11. Single-photon light detection with transition-edge sensors

    International Nuclear Information System (INIS)

    Rajteri, M.; Taralli, E.; Portesi, C.; Monticone, E.

    2008-01-01

    Transition-Edge Sensors (TESs) are micro calorimeters that measure the energy of incident single-photons by the resistance increase of a superconducting film biased within the superconducting-to-normal transition. TES are able to detect single photons from x-ray to IR with an intrinsic energy resolution and photon-number discrimination capability. Metrological, astronomical and quantum communication applications are the fields where these properties can be particularly important. In this work, we report about characterization of different TESs based on Ti films. Single-photons have been detected from 200 nm to 800 nm working at T c ∼ 100 m K. Using a pulsed laser at 690 nm we have demonstrated the capability to resolve up to five photons.

  12. Phase transitions in single macromolecules: Loop-stretch transition versus loop adsorption transition in end-grafted polymer chains

    Science.gov (United States)

    Zhang, Shuangshuang; Qi, Shuanhu; Klushin, Leonid I.; Skvortsov, Alexander M.; Yan, Dadong; Schmid, Friederike

    2018-01-01

    We use Brownian dynamics simulations and analytical theory to compare two prominent types of single molecule transitions. One is the adsorption transition of a loop (a chain with two ends bound to an attractive substrate) driven by an attraction parameter ɛ and the other is the loop-stretch transition in a chain with one end attached to a repulsive substrate, driven by an external end-force F applied to the free end. Specifically, we compare the behavior of the respective order parameters of the transitions, i.e., the mean number of surface contacts in the case of the adsorption transition and the mean position of the chain end in the case of the loop-stretch transition. Close to the transition points, both the static behavior and the dynamic behavior of chains with different length N are very well described by a scaling ansatz with the scaling parameters (ɛ - ɛ*)Nϕ (adsorption transition) and (F - F*)Nν (loop-stretch transition), respectively, where ϕ is the crossover exponent of the adsorption transition and ν is the Flory exponent. We show that both the loop-stretch and the loop adsorption transitions provide an exceptional opportunity to construct explicit analytical expressions for the crossover functions which perfectly describe all simulation results on static properties in the finite-size scaling regime. Explicit crossover functions are based on the ansatz for the analytical form of the order parameter distributions at the respective transition points. In contrast to the close similarity in equilibrium static behavior, the dynamic relaxation at the two transitions shows qualitative differences, especially in the strongly ordered regimes. This is attributed to the fact that the surface contact dynamics in a strongly adsorbed chain is governed by local processes, whereas the end height relaxation of a strongly stretched chain involves the full spectrum of Rouse modes.

  13. Ferroelectric phase transition in Ga2Te3 single crystals

    Science.gov (United States)

    Gamal, G. A.; Abdalrahman, M. M.; Ashraf, M. I.; Eman, H. J.

    2005-01-01

    Measurements of the electrical conductivity and Hall effect were carried out in a wide temperature range (200-500 K) for Ga2Te3 crystals. The crystals were grown in single crystalline form by making a modification of the travelling heater method technique. The measurements revealed unusual observations in the electric conductivity and Hall mobility indicating the presence of some type of phase transitions at about 430 K. So, ferroelectric behavior was examined for confirming the presence of second-order (ferroelectric) phase transition. An energy gap of 1.21 eV and depth of the impurity center of 0.11 eV were found.

  14. Biosynthetic consequences of multiple sequential post-transition-state bifurcations

    Science.gov (United States)

    Hong, Young Joo; Tantillo, Dean J.

    2014-02-01

    Selectivity in chemical reactions that form complex molecular architectures from simpler precursors is usually rationalized by comparing competing transition-state structures that lead to different possible products. Herein we describe a system for which a single transition-state structure leads to the formation of many isomeric products via pathways that feature multiple sequential bifurcations. The reaction network described connects the pimar-15-en-8-yl cation to miltiradiene, a tricyclic diterpene natural product, and isomers via cyclizations and/or rearrangements. The results suggest that the selectivity of the reaction is controlled by (post-transition-state) dynamic effects, that is, how the carbocation structure changes in response to the distribution of energy in its vibrational modes. The inherent dynamical effects revealed herein (characterized through quasiclassical direct dynamics calculations using density functional theory) have implications not only for the general principles of selectivity prediction in systems with complex potential energy surfaces, but also for the mechanisms of terpene synthase enzymes and their evolution. These findings redefine the challenges faced by nature in controlling the biosynthesis of complex natural products.

  15. Transitional states of central serotonin receptors in Parkinson's disease

    International Nuclear Information System (INIS)

    Kienzl, E.; Riederer, P.; Jellinger, K.; Wesemann, W.; Marburg Univ.

    1981-01-01

    Crude membrane preparations from the frontal cortex of controls and pakinsonian patients were used to demonstrate affinity changes of the specific 3 H-5-hydroxytryptamine (5-HT) binding sites. Two such sites were noteable in controls, a finding consistent with earlier observations. In Parkinson's disease, both high- and low-affinity sites are significantly decreased. Additional experiments either with prolonged incubation times or pre-incubation with N-ethylmaleimide change the two affinities to a single high-affinity or low-affinity constant. The concept of transitional states of 5-HT receptors is discussed and seems to have important implications in the treatment of parkinsonism. (author)

  16. Magnetic phase transitions in Er7Rh3 studied on single crystals

    International Nuclear Information System (INIS)

    Tsutaoka, Takanori; Obata, Keisuke; Cheyvuth, Seng; Koyama, Keiichi

    2014-01-01

    Highlights: • Magnetic and electrical properties of Er 7 Rh 3 were studied on single crystals. • The magnetic phase diagram along the c-axis was constructed. • The field-induced magnetic transitions in Er 7 Rh 3 can be explained by the magnetic structure with two magnetic propagation vectors. • The anomalies of electrical resistivity can also be described by the magnetic structure in Er 7 Rh 3 . - Abstract: Magnetic phase transitions in Er 7 Rh 3 with the Th 7 Fe 3 type hexagonal structure have been studied on single crystals by measuring magnetization, magnetic susceptibility and electrical resistivity. Er 7 Rh 3 possesses antiferromagnetic state below T N = 13 K. In the ordered state, the two successive magnetic transitions at T t1 = 6.2 K and T t2 = 4.5 K were observed. Several field-induced magnetic transitions were also observed along the a- and c-axes below T N ; magnetic field H – temperature T phase diagram along the c-axis was constructed. The field-induced magnetic transitions in Er 7 Rh 3 can be explained by the magnetic structure with two magnetic propagation vectors which were derived by the previous neutron diffraction studies. Electrical resistivity shows humps just below the magnetic transition temperatures, T N and T t1 due to the super-zone gap formation at the Fermi level; these anomalies can also be described by the magnetic structure changes in Er 7 Rh 3

  17. Vibrational nonadiabaticity and tunneling effects in transition state theory

    International Nuclear Information System (INIS)

    Marcus, R.A.

    1979-01-01

    The usual quantum mechanical derivation of transition state theory is a statistical one (a quasi-equilibrium is assumed) or dynamical. The typical dynamical one defines a set of internal states and assumes vibrational adiabaticity. Effects of nonadiabaticity before and after the transition state are included in the present derivation, assuming a classical treatment of the reaction coordinate. The relation to a dynamical derivation of classical mechanical transition state theory is described, and tunneling effects are considered

  18. Antiferromagnetic transition in EuCu sub 2 Ge sub 2 single crystals

    CERN Document Server

    Hossain, Z; Yuan, H Q; Sparn, G

    2003-01-01

    Single crystals of EuCu sub 2 Ge sub 2 were grown and characterized using electrical resistivity, magnetization, specific heat and magnetoresistance measurements. The crystals exhibit antiferromagnetic transitions at T sub N sub 1 = 9 K and T sub N sub 2 = 5 K. The T sub N of the flux-grown single crystals reported here are lower than that reported for the polycrystalline sample (T sub N = 13 K) in the literature (Felner and Nowik 1978 J. Phys. Chem. Solids 39 763). The magnetoresistance is positive in the ordered state and negative in the paramagnetic state. The magnetic order could not be suppressed up to a pressure of 25 kbar.

  19. Pressure-induced topological phase transitions and structural transition in 1T-TiTe2 single crystal

    Science.gov (United States)

    Zhang, Min; Wang, Xiangqi; Rahman, Azizur; Zeng, Qunsong; Huang, Da; Dai, Rucheng; Wang, Zhongping; Zhang, Zengming

    2018-01-01

    High pressure in situ Raman scattering and electrical resistivity measurements were performed to investigate the phase transitions in a semimetal 1T-TiTe2 single crystal up to 17 GPa. Combining anomalous experimental results with the electronic band structures and Z2 topological invariants in calculations, two topological phase transitions and one structural phase transition were confirmed at 1.7 GPa, 3 GPa, and 8 GPa, respectively. These two topological transformations are due to the enhanced orbital hybridization followed by a few of band inversions near the Fermi level, and the further parity analysis manifested that the phases II and III correspond to a strong topological state and a weak topological state, respectively. The rich topology variation of 1T-TiTe2 under high pressure provides a potential candidate for understanding the relevant topology physics and probable applications. The current results also demonstrate that Raman spectroscopy and electrical transport measurements are efficient tools to detect the topological phase transition under high pressure.

  20. Spatiotemporal dynamics of the spin transition in [Fe (HB(tz)3) 2] single crystals

    Science.gov (United States)

    Ridier, Karl; Rat, Sylvain; Shepherd, Helena J.; Salmon, Lionel; Nicolazzi, William; Molnár, Gábor; Bousseksou, Azzedine

    2017-10-01

    The spatiotemporal dynamics of the spin transition have been thoroughly investigated in single crystals of the mononuclear spin-crossover (SCO) complex [Fe (HB (tz )3)2] (tz = 1 ,2 ,4-triazol-1-yl) by optical microscopy. This compound exhibits an abrupt spin transition centered at 334 K with a narrow thermal hysteresis loop of ˜1 K (first-order transition). Most single crystals of this compound reveal exceptional resilience upon repeated switching (several hundred cycles), which allowed repeatable and quantitative measurements of the spatiotemporal dynamics of the nucleation and growth processes to be carried out. These experiments revealed remarkable properties of the thermally induced spin transition: high stability of the thermal hysteresis loop, unprecedented large velocities of the macroscopic low-spin/high-spin phase boundaries up to 500 µm/s, and no visible dependency on the temperature scan rate. We have also studied the dynamics of the low-spin → high-spin transition induced by a local photothermal excitation generated by a spatially localized (Ø = 2 μ m ) continuous laser beam. Interesting phenomena have been evidenced both in quasistatic and dynamic conditions (e.g., threshold effects and long incubation periods, thermal activation of the phase boundary propagation, stabilization of the crystal in a stationary biphasic state, and thermal cutoff frequency). These measurements demonstrated the importance of thermal effects in the transition dynamics, and they enabled an accurate determination of the thermal properties of the SCO compound in the framework of a simple theoretical model.

  1. Microscopic model of the glass transition and the glassy state

    International Nuclear Information System (INIS)

    Shukla, P.

    1982-07-01

    A microscopic model of the glass transition and the glassy state is presented. It is exactly solvable, and offers a unified view of the equilibrium and non-equilibrium aspects of the glass transition. It also provides a statistical-mechanical justification of the irreversible thermodynamic models of the glass transition proposed earlier. (author)

  2. M1 transitions between superdeformed states in 195Tl

    International Nuclear Information System (INIS)

    Zheng Xing; Xingqu Chen; Xiaochun Wang

    1996-01-01

    Using a triaxial-particle-rotor model, the quadrupole and dipole transition energies, kinematic and dynamic moments of inertia, electromagnetic transition probabilities and the relative intensity of the E2 γ-transitions are calculated for superdeformed bands in 195 Tl. A strong perturbation effect of rotation on transition energies and M1 and E2 transitions of superdeformed states is investigated. The total M1 transitions, enhanced by internal conversion, are expected to compete strongly with the E2 γ-ray at low spins in the superdeformed 195 Tl nucleus. (author)

  3. Single-Particle States in $^{133}$Sn

    CERN Multimedia

    Huck, A

    2002-01-01

    % IS338 \\\\ \\\\ It is suggested to investigate the $\\beta^- $-decay of $^{133}$In and $^{134}$In in order to determine the single-particle states in $^{133}$Sn, which are so far unknown and needed for the shell-model description of the region close to $^{132}$Sn. Large hyper-pure Ge-detectors will be used for the $\\gamma$-ray spectroscopy. In the experiments with $^{134}$In, delayed neutrons in coincidence with $\\gamma$-rays from excited states in $^{133}$Sn provide the opportunity for a very selective detection of the states in question.

  4. The Heisenberg picture for single photon states

    International Nuclear Information System (INIS)

    Pienaar, Jacques; Myers, Casey; Ralph, Timothy C.

    2011-01-01

    In the context of quantum field theory, the Heisenberg picture has a distinct advantage over the Schrodinger picture because the Schrodinger picture requires us to transform the vacuum state itself, which can be intractable in the case of non-inertial reference frames, whereas the Heisenberg picture allows us to keep the same vacuum state and only transform the operators. However, the Heisenberg calculation requires the operators to already be expressed as a function of creation and annihilation operators acting on the original vacuum, whereas calculations in quantum information and quantum computation use operators that act on qubit states, necessarily containing particles. The relationship between the operators acting on these states and the operators acting on the vacuum state has remained elusive. We derive such an expression using an explicit model for single-particle production from the vacuum.

  5. Tracking the embryonic stem cell transition from ground state pluripotency.

    Science.gov (United States)

    Kalkan, Tüzer; Olova, Nelly; Roode, Mila; Mulas, Carla; Lee, Heather J; Nett, Isabelle; Marks, Hendrik; Walker, Rachael; Stunnenberg, Hendrik G; Lilley, Kathryn S; Nichols, Jennifer; Reik, Wolf; Bertone, Paul; Smith, Austin

    2017-04-01

    Mouse embryonic stem (ES) cells are locked into self-renewal by shielding from inductive cues. Release from this ground state in minimal conditions offers a system for delineating developmental progression from naïve pluripotency. Here, we examine the initial transition process. The ES cell population behaves asynchronously. We therefore exploited a short-half-life Rex1::GFP reporter to isolate cells either side of exit from naïve status. Extinction of ES cell identity in single cells is acute. It occurs only after near-complete elimination of naïve pluripotency factors, but precedes appearance of lineage specification markers. Cells newly departed from the ES cell state display features of early post-implantation epiblast and are distinct from primed epiblast. They also exhibit a genome-wide increase in DNA methylation, intermediate between early and late epiblast. These findings are consistent with the proposition that naïve cells transition to a distinct formative phase of pluripotency preparatory to lineage priming. © 2017. Published by The Company of Biologists Ltd.

  6. Probing the transition state for nucleic acid hybridization using phi-value analysis.

    Science.gov (United States)

    Kim, Jandi; Shin, Jong-Shik

    2010-04-27

    Genetic regulation by noncoding RNA elements such as microRNA and small interfering RNA (siRNA) involves hybridization of a short single-stranded RNA with a complementary segment in a target mRNA. The physical basis of the hybridization process between the structured nucleic acids is not well understood primarily because of the lack of information about the transition-state structure. Here we use transition-state theory, inspired by phi-value analysis in protein folding studies, to provide quantitative analysis of the relationship between changes in the secondary structure stability and the activation free energy. Time course monitoring of the hybridization reaction was performed under pseudo-steady-state conditions using a single fluorophore. The phi-value analysis indicates that the native secondary structure remains intact in the transition state. The nativelike transition state was confirmed via examination of the salt dependence of the hybridization kinetics, indicating that the number of sodium ions associated with the transition state was not substantially affected by changes in the native secondary structure. These results propose that hybridization between structured nucleic acids undergoes a transition state leading to formation of a nucleation complex and then is followed by sequential displacement of preexisting base pairings involving successive small energy barriers. The proposed mechanism might provide new insight into physical processes during small RNA-mediated gene silencing, which is essential to selection of a target mRNA segment for siRNA design.

  7. First observation of two-electron one-photon transitions in single-photon K-shell double ionization.

    Science.gov (United States)

    Hoszowska, J; Dousse, J-Cl; Szlachetko, J; Kayser, Y; Cao, W; Jagodziński, P; Kavčič, M; Nowak, S H

    2011-07-29

    Experimental evidence for the correlated two-electron one-photon transitions (1s(-2)→2s(-1)2p(-1)) following single-photon K-shell double ionization is reported. The double K-shell vacancy states in solid Mg, Al, and Si were produced by means of monochromatized synchrotron radiation, and the two-electron one-photon radiative transitions were observed by using a wavelength dispersive spectrometer. The two-electron one-photon transition energies and the branching ratios of the radiative one-electron to two-electron transitions were determined and compared to available perturbation theory predictions and configuration interaction calculations.

  8. Probing Critical Point Energies of Transition Metal Dichalcogenides: Surprising Indirect Gap of Single Layer WSe 2

    KAUST Repository

    Zhang, Chendong

    2015-09-21

    By using a comprehensive form of scanning tunneling spectroscopy, we have revealed detailed quasi-particle electronic structures in transition metal dichalcogenides, including the quasi-particle gaps, critical point energy locations, and their origins in the Brillouin zones. We show that single layer WSe surprisingly has an indirect quasi-particle gap with the conduction band minimum located at the Q-point (instead of K), albeit the two states are nearly degenerate. We have further observed rich quasi-particle electronic structures of transition metal dichalcogenides as a function of atomic structures and spin-orbit couplings. Such a local probe for detailed electronic structures in conduction and valence bands will be ideal to investigate how electronic structures of transition metal dichalcogenides are influenced by variations of local environment.

  9. Counting efficiencies by liquid scintillation counting. Single isomeric transitions

    International Nuclear Information System (INIS)

    Grau Carles, A.; Grau Malonda, A.

    1995-09-01

    In this work we present liquid scintillation counting efficiency tables for several radionuclides with single isomeric transitions, in which electron conversion and gamma emission processes are competitive. We study the radionuclides: ''58m CO, ''77mSE, ''79mBR, ''87mSR,''89mY,''93mNB,''103mRh, ''107mAG, ''109mAG, ''113mIn, ''131mXe; ''133mXe,''135mBa, ''167mEr, for two different scintillators, Ultima-Gold and Insta-Gel. We consider volumes of 10 and 15 mL for Ultima gold, and 15 mL for Insta-Gel

  10. Counting efficiencies by liquid scintillation counting. Single isomeric transitions

    International Nuclear Information System (INIS)

    Grau Carles, A.; Grau Malonda, A.

    1995-01-01

    In this work we present liquid scintillation counting efficiency tables for several radionuclides with single isomeric transitions, in which electron conversion and gamma emission processes are competitive. We study the radionuclides: 58mCo, 77mSe, 79mBr, 87mSr, S9mY, 93mNb, 103mRh, 107mAg, 109mAg, 113mIn, 131mXe, I33mXe, 135raBa, 137mBa, 167raEr, for two different scintillators, Ultima-Gold and Insta-Gel. We consider volumes of 10 and 15 mL for Ultima Gold, and 15 mL for Insta-Gel. (Author) 18 refs

  11. Direct measurement and modulation of single-molecule coordinative bonding forces in a transition metal complex

    DEFF Research Database (Denmark)

    Hao, Xian; Zhu, Nan; Gschneidtner, Tina

    2013-01-01

    remain a daunting challenge. Here we demonstrate an interdisciplinary and systematic approach that enables measurement and modulation of the coordinative bonding forces in a transition metal complex. Terpyridine is derived with a thiol linker, facilitating covalent attachment of this ligand on both gold...... substrate surfaces and gold-coated atomic force microscopy tips. The coordination and bond breaking between terpyridine and osmium are followed in situ by electrochemically controlled atomic force microscopy at the single-molecule level. The redox state of the central metal atom is found to have......Coordination chemistry has been a consistently active branch of chemistry since Werner's seminal theory of coordination compounds inaugurated in 1893, with the central focus on transition metal complexes. However, control and measurement of metal-ligand interactions at the single-molecule level...

  12. Improving Upon String Methods for Transition State Discovery.

    Science.gov (United States)

    Chaffey-Millar, Hugh; Nikodem, Astrid; Matveev, Alexei V; Krüger, Sven; Rösch, Notker

    2012-02-14

    Transition state discovery via application of string methods has been researched on two fronts. The first front involves development of a new string method, named the Searching String method, while the second one aims at estimating transition states from a discretized reaction path. The Searching String method has been benchmarked against a number of previously existing string methods and the Nudged Elastic Band method. The developed methods have led to a reduction in the number of gradient calls required to optimize a transition state, as compared to existing methods. The Searching String method reported here places new beads on a reaction pathway at the midpoint between existing beads, such that the resolution of the path discretization in the region containing the transition state grows exponentially with the number of beads. This approach leads to favorable convergence behavior and generates more accurate estimates of transition states from which convergence to the final transition states occurs more readily. Several techniques for generating improved estimates of transition states from a converged string or nudged elastic band have been developed and benchmarked on 13 chemical test cases. Optimization approaches for string methods, and pitfalls therein, are discussed.

  13. Factorised steady states and condensation transitions in ...

    Indian Academy of Sciences (India)

    Systems driven out of equilibrium can often exhibit behaviour not seen in systems in thermal equilibrium – for example phase transitions in one-dimensional systems. In this talk I will review a simple model of a nonequilibrium system known as the `zero-range process' and its recent developments. The nonequilibrium ...

  14. Arab States in Transition | IDRC - International Development ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    ... and investigate the interplay between political and economic factors. Workshops will be convened involving experts, activists, policymakers and other actors involved in their country's transition. The workshops will allow the participants to define the problems as they see them, and point the researchers in new directions.

  15. In vivo single cell analysis reveals Gata2 dynamics in cells transitioning to hematopoietic fate.

    Science.gov (United States)

    Eich, Christina; Arlt, Jochen; Vink, Chris S; Solaimani Kartalaei, Parham; Kaimakis, Polynikis; Mariani, Samanta A; van der Linden, Reinier; van Cappellen, Wiggert A; Dzierzak, Elaine

    2018-01-02

    Cell fate is established through coordinated gene expression programs in individual cells. Regulatory networks that include the Gata2 transcription factor play central roles in hematopoietic fate establishment. Although Gata2 is essential to the embryonic development and function of hematopoietic stem cells that form the adult hierarchy, little is known about the in vivo expression dynamics of Gata2 in single cells. Here, we examine Gata2 expression in single aortic cells as they establish hematopoietic fate in Gata2Venus mouse embryos. Time-lapse imaging reveals rapid pulsatile level changes in Gata2 reporter expression in cells undergoing endothelial-to-hematopoietic transition. Moreover, Gata2 reporter pulsatile expression is dramatically altered in Gata2 +/- aortic cells, which undergo fewer transitions and are reduced in hematopoietic potential. Our novel finding of dynamic pulsatile expression of Gata2 suggests a highly unstable genetic state in single cells concomitant with their transition to hematopoietic fate. This reinforces the notion that threshold levels of Gata2 influence fate establishment and has implications for transcription factor-related hematologic dysfunctions. © 2018 Eich et al.

  16. Quantifying the limits of transition state theory in enzymatic catalysis.

    Science.gov (United States)

    Zinovjev, Kirill; Tuñón, Iñaki

    2017-11-21

    While being one of the most popular reaction rate theories, the applicability of transition state theory to the study of enzymatic reactions has been often challenged. The complex dynamic nature of the protein environment raised the question about the validity of the nonrecrossing hypothesis, a cornerstone in this theory. We present a computational strategy to quantify the error associated to transition state theory from the number of recrossings observed at the equicommittor, which is the best possible dividing surface. Application of a direct multidimensional transition state optimization to the hydride transfer step in human dihydrofolate reductase shows that both the participation of the protein degrees of freedom in the reaction coordinate and the error associated to the nonrecrossing hypothesis are small. Thus, the use of transition state theory, even with simplified reaction coordinates, provides a good theoretical framework for the study of enzymatic catalysis. Copyright © 2017 the Author(s). Published by PNAS.

  17. Religion, state, society and identity in transition: Ukraine

    NARCIS (Netherlands)

    van der Laarse, R.; Cherenkov, M.N.; Proshak, V.V.; Mykhalchuk, T.

    2015-01-01

    State-society-identity relations could be defined as interaction(s) between state institutions, societal groups and individuals living within the borders of a (political) community/ state. These relations are never static, but vibrant, being in constant transition under the influence of cultural,

  18. Policy to Performance: State ABE Transition Systems Report. Transitioning Adults to Opportunity

    Science.gov (United States)

    Alamprese, Judith A.

    2012-01-01

    The U.S. Department of Education's Policy to Performance project was funded in 2009 to build the capacity of state adult basic education (ABE) staff to develop and implement policies and practices that would support an ABE transition system. Policy to Performance states were selected though a competitive process. State adult education directors…

  19. Growth, economic development and structural transition in small vulnerable states

    OpenAIRE

    Read, Robert

    2001-01-01

    This paper reviews the critical theoretical and policy issues relating to growth, economic development and structural transition in small states. The paper discusses alternative perspectives on small size and highlights the salient characteristics which give rise to their economic sub-optimality. The theoretical and empirical relationship between size and growth is reviewed, including recent inferences relating to structural transition and comparative advantage in small states. This discussio...

  20. Magnetic Ground State Properties of Transition Metals

    DEFF Research Database (Denmark)

    Andersen, O. K.; Madsen, J.; Poulsen, U. K.

    1977-01-01

    We review a simple one-electron theory of the magnetic and cohesive properties of ferro- and nearly ferromagnetic transition metals at 0 K. The theory is based on the density functional formalism, it makes use of the local spin density and atomic sphere approximations and it may, with further...... approximations, be reduced to the Stoner model. Results for the volume dependence of the ferromagnetic moment and the electronic pressure of bcc, fcc and hcp Fe are presented, together with theoretical values for the equilibrium atomic volume, the bulk modulus, the ferromagnetic moment, the spin susceptibility...

  1. Gamma transitions between compound states in spherical nuclei

    International Nuclear Information System (INIS)

    Kadmenskij, S.G.; Markushev, V.P.; Furman, V.I.

    1980-01-01

    Average values of the reduced γ widths and their dispersions are investigated, basing on the Wigner statistical matrix method, for γ transitions from a compound state c into a less-energy excited state f of an arbitrary complexity in spherical nuclei. It is shown that in all the cases of practical interest the Porter-Thomas distribution is valid for the γ widths. It is found that in the γ transitions between compound states c and c' with Esub(γ) <= 2 MeV the dominating role is played by the M1 transitions due to the main multiquasiparticle states of c, and by the E1 transitions, due to small components of the state c. In framework of the existent theoretical schemes it is shown that the strength functions of the M1 and E1 transitions between the compound states with Esub(γ) <2 MeV are close. It is deduced thet the variant of the M1 transitions is preferable in view of the experimental results on the (n, γα) reactions induced by thermal and resonance neutrons

  2. 34 CFR 200.12 - Single State accountability system.

    Science.gov (United States)

    2010-07-01

    ... 34 Education 1 2010-07-01 2010-07-01 false Single State accountability system. 200.12 Section 200... Improving Basic Programs Operated by Local Educational Agencies State Accountability System § 200.12 Single State accountability system. (a)(1) Each State must demonstrate in its State plan that the State has...

  3. Single-particle spectral function of a generalized Hubbard model: Metal-insulator transition

    Science.gov (United States)

    Gagliano, E. R.; Aligia, A. A.; Arrachea, Liliana; Avignon, Michel

    1995-05-01

    A generalized Hubbard model with correlated hoppings is studied at half filling using exact diagonalization methods. For certain values of the hopping parameters our results for several static properties, the Drude weight and the single-particle spectra function, suggest the occurrence of a metal-insulator transition (MIT) at a finite value of the local Coulomb interaction Uc. We identify the regions of the hopping parameters where the MIT is of the Mott type. In these regions, for large Ustate.

  4. Factorised steady states and condensation transitions in ...

    Indian Academy of Sciences (India)

    Scotland. E-mail: martin@ph.ed.ac.uk. Abstract. Systems driven out of equilibrium can often exhibit behaviour not seen in systems in thermal equilibrium – for example phase ... weights rather it will be a nonequilibrium steady state. ... particular cases are: if u(m) = m then the dynamics of each particle is independent.

  5. TPmsm: Estimation of the Transition Probabilities in 3-State Models

    Directory of Open Access Journals (Sweden)

    Artur Araújo

    2014-12-01

    Full Text Available One major goal in clinical applications of multi-state models is the estimation of transition probabilities. The usual nonparametric estimator of the transition matrix for non-homogeneous Markov processes is the Aalen-Johansen estimator (Aalen and Johansen 1978. However, two problems may arise from using this estimator: first, its standard error may be large in heavy censored scenarios; second, the estimator may be inconsistent if the process is non-Markovian. The development of the R package TPmsm has been motivated by several recent contributions that account for these estimation problems. Estimation and statistical inference for transition probabilities can be performed using TPmsm. The TPmsm package provides seven different approaches to three-state illness-death modeling. In two of these approaches the transition probabilities are estimated conditionally on current or past covariate measures. Two real data examples are included for illustration of software usage.

  6. Diels-Alder reactions of allene with benzene and butadiene: concerted, stepwise, and ambimodal transition states.

    Science.gov (United States)

    Pham, Hung V; Houk, K N

    2014-10-03

    Multiconfigurational complete active space methods (CASSCF and CASPT2) have been used to investigate the (4 + 2) cycloadditions of allene with butadiene and with benzene. Both concerted and stepwise radical pathways were examined to determine the mechanism of the Diels-Alder reactions with an allene dienophile. Reaction with butadiene occurs via a single ambimodal transition state that can lead to either the concerted or stepwise trajectories along the potential energy surface, while reaction with benzene involves two separate transition states and favors the concerted mechanism relative to the stepwise mechanism via a diradical intermediate.

  7. Diels–Alder Reactions of Allene with Benzene and Butadiene: Concerted, Stepwise, and Ambimodal Transition States

    Science.gov (United States)

    2015-01-01

    Multiconfigurational complete active space methods (CASSCF and CASPT2) have been used to investigate the (4 + 2) cycloadditions of allene with butadiene and with benzene. Both concerted and stepwise radical pathways were examined to determine the mechanism of the Diels–Alder reactions with an allene dienophile. Reaction with butadiene occurs via a single ambimodal transition state that can lead to either the concerted or stepwise trajectories along the potential energy surface, while reaction with benzene involves two separate transition states and favors the concerted mechanism relative to the stepwise mechanism via a diradical intermediate. PMID:25216056

  8. GENESIS - The GENEric SImulation System for Modelling State Transitions.

    Science.gov (United States)

    Gillman, Matthew S

    2017-09-20

    This software implements a discrete time Markov chain model, used to model transitions between states when the transition probabilities are known a priori . It is highly configurable; the user supplies two text files, a "state transition table" and a "config file", to the Perl script genesis.pl. Given the content of these files, the script generates a set of C++ classes based on the State design pattern, and a main program, which can then be compiled and run. The C++ code generated is based on the specification in the text files. Both multiple branching and bi-directional transitions are allowed. The software has been used to model the natural histories of colorectal cancer in Mexico. Although written primarily to model such disease processes, it can be used in any process which depends on discrete states with known transition probabilities between those states. One suitable area may be in environmental modelling. A test suite is supplied with the distribution. Due to its high degree of configurability and flexibility, this software has good re-use potential. It is stored on the Figshare repository.

  9. Single-Helical-Axis States in Reversed-Field-Pinch Plasmas

    International Nuclear Information System (INIS)

    Lorenzini, R.; Terranova, D.; Alfier, A.; Innocente, P.; Martines, E.; Pasqualotto, R.; Zanca, P.

    2008-01-01

    The transition to a new magnetic topology, characterized by a quasi-single-helicity state with a single helical magnetic axis has been experimentally observed for the first time in a reversed-field-pinch plasma. The occurrence of the new state, which has been dubbed a single-helical-axis state, was found to provide magnetic chaos healing and enhanced thermal content of the plasma. The helical structure extends on both sides of the vessel geometric axis, and is related to exceeding a threshold in the ratio between the amplitude of the dominant MHD mode and the amplitude of the secondary ones

  10. Complexity and state-transitions in social dependence networks

    Directory of Open Access Journals (Sweden)

    Giuliano Pistolesi

    2001-01-01

    Full Text Available Computation of complexity in Social Dependence Networks is an interesting research domain to understand evolution processes and group exchange dynamics in natural and artificial intelligent Multi-Agent Systems. We perform an agent-based simulation by NET-PLEX (Conte and Pistolesi, 2000, a new software system able both to build interdependence networks tipically emerging in Multi-Agent System scenarios and to investigate complexity phenomena, i.e., unstability and state-transitions like Hopf bifurcation (Nowak and Lewenstein, 1994, and to describe social self organization phenomena emerging in these artificial social systems by means of complexity measures similar to those introduced by Hubermann and Hogg (1986. By performing analysis of complexity in these kind of artificial societies we observed interesting phenomena in emerging organizations that suggest state-transitions induced by critical configurations of parameters describing the social system similar to those observed in many studies on state-transitions in bifurcation chaos (Schuster, 1988; Ruelle, 1989.

  11. Single-Column Model Simulations of Subtropical Marine Boundary-Layer Cloud Transitions Under Weakening Inversions

    Science.gov (United States)

    Neggers, R. A. J.; Ackerman, A. S.; Angevine, W. M.; Bazile, E.; Beau, I.; Blossey, P. N.; Boutle, I. A.; de Bruijn, C.; Cheng, A.; van der Dussen, J.; Fletcher, J.; Dal Gesso, S.; Jam, A.; Kawai, H.; Cheedela, S. K.; Larson, V. E.; Lefebvre, M.-P.; Lock, A. P.; Meyer, N. R.; de Roode, S. R.; de Rooy, W.; Sandu, I.; Xiao, H.; Xu, K.-M.

    2017-10-01

    Results are presented of the GASS/EUCLIPSE single-column model intercomparison study on the subtropical marine low-level cloud transition. A central goal is to establish the performance of state-of-the-art boundary-layer schemes for weather and climate models for this cloud regime, using large-eddy simulations of the same scenes as a reference. A novelty is that the comparison covers four different cases instead of one, in order to broaden the covered parameter space. Three cases are situated in the North-Eastern Pacific, while one reflects conditions in the North-Eastern Atlantic. A set of variables is considered that reflects key aspects of the transition process, making use of simple metrics to establish the model performance. Using this method, some longstanding problems in low-level cloud representation are identified. Considerable spread exists among models concerning the cloud amount, its vertical structure, and the associated impact on radiative transfer. The sign and amplitude of these biases differ somewhat per case, depending on how far the transition has progressed. After cloud breakup the ensemble median exhibits the well-known "too few too bright" problem. The boundary-layer deepening rate and its state of decoupling are both underestimated, while the representation of the thin capping cloud layer appears complicated by a lack of vertical resolution. Encouragingly, some models are successful in representing the full set of variables, in particular, the vertical structure and diurnal cycle of the cloud layer in transition. An intriguing result is that the median of the model ensemble performs best, inspiring a new approach in subgrid parameterization.

  12. Urban Quality vs single travel: the Personal Rapid Transit

    Directory of Open Access Journals (Sweden)

    Carmela Gargiulo

    2011-10-01

    Full Text Available The great increase in the demand for private mobility with the con­sequent macroscopic growth of channels to meet it, together with short-sighted policies of transport and urban development spread above all in Italy, has produced pollution, congestion and unlivability in the last fifty years.The hope of assuring the maximum individual freedom of travel to people living in consolidated urban centres, in addition to those living in the outskirts arisen and developed without any reasonable urban logic, still goes on producing congestion of vehicular traffic, conside­red, by the majority of citizens, the main cause of the deterioration of the quality of life in our cities.Indeed, also the most recent reports on environment in Italian cities show that the pollution levels are increasing in the big cities, although the news are full of very expensive projects, innovative solutions and unexpected goals continuously shown by public administrations. One of the main environmental detractors is car traffic, which has recently gained on public transport. unlike the previous period. Most of mobility policies implemented in our cities aims at reaching the modal balance by means of measures for controlling and managing the demand for mobility, for mitigating traffic and limiting circulation., such as the road pricing and the parking strategies; for developing and increasing public transport and not polluting means of transport, car sharing and car pooling.All of them have showed modest results both in terms of pollution reduction and vehicular traffic reduction. For over fifty years, mostly in the United States, the Personal Rapid Transit has been tested, a system of public transport trying to join two apparently incompatible factors: the possibility of assuring individual travels and the need for decreasing the levels of acoustic and air pol­lution as well as the congestion caused by private vehicular traffic. In Italy this system is still not well known

  13. Urban Quality vs Single Travel: the Personal Rapid Transit

    Directory of Open Access Journals (Sweden)

    Carmela Gargiulo

    2011-02-01

    Full Text Available The great increase in the demand for private mobility with theconsequent macroscopic growth of channels to meet it, togetherwith short-sighted policies of transport and urban developmentspread above all in Italy, has produced pollution, congestion andunlivability in the last fifty years.The hope of assuring the maximum individual freedom of travel topeople living in consolidated urban centres, in addition to thoseliving in the outskirts arisen and developed without any reasonableurban logic, still goes on producing congestion of vehicular traffic,considered, by the majority of citizens, the main cause of thedeterioration of the quality of life in our cities.Indeed, also the most recent reports on environment in Italiancities show that the pollution levels are increasing in the big cities,although the news are full of very expensive projects, innovativesolutions and unexpected goals continuously shown by publicadministrations. One of the main environmental detractors is cartraffic, which has recently gained on public transport. unlike theprevious period.Most of mobility policies implemented in our cities aims at reachingthe modal balance by means of measures for controlling and managingthe demand for mobility, for mitigating traffic and limiting circulation.,such as the road pricing and the parking strategies; for developingand increasing public transport and not polluting means of transport,car sharing and car pooling.All of them have showed modest results both in terms of pollutionreduction and vehicular traffic reduction.For over fifty years, mostly in the United States, the Personal RapidTransit has been tested, a system of public transport trying to jointwo apparently incompatible factors: the possibility of assuringindividual travels and the need for decreasing the levels of acousticand air pollution as well as the congestion caused by privatevehicular traffic.In Italy this system is still not well known despite the versatility ofits fields

  14. Modelling transition states of a small once-through boiler

    Energy Technology Data Exchange (ETDEWEB)

    Talonpoika, T. [Lappeenranta Univ. of Technology (Finland). Dept. of Energy Technology

    1997-12-31

    This article presents a model for the unsteady dynamic behaviour of a once-through counter flow boiler that uses an organic working fluid. The boiler is a compact waste-heat boiler without a furnace and it has a preheater, a vaporiser and a superheater. The relative lengths of the boiler parts vary with the operating conditions since they are all parts of a single tube. The boiler model is presented using a selected example case that uses toluene as the process fluid and flue gas from natural gas combustion as the heat source. The dynamic behaviour of the boiler means transition from the steady initial state towards another steady state that corresponds to the changed process conditions. The solution method chosen is to find such a pressure of the process fluid that the mass of the process fluid in the boiler equals the mass calculated using the mass flows into and out of the boiler during a time step, using the finite difference method. A special method of fast calculation of the thermal properties is used, because most of the calculation time is spent in calculating the fluid properties. The boiler is divided into elements. The values of the thermodynamic properties and mass flows are calculated in the nodes that connect the elements. Dynamic behaviour is limited to the process fluid and tube wall, and the heat source is regarded as to be steady. The elements that connect the preheater to the vaporiser and the vaporiser to the superheater are treated in a special way that takes into account a flexible change from one part to the other. The initial state of the boiler is received from a steady process model that is not a part of the boiler model. The known boundary values that may vary during the dynamic calculation were the inlet temperature and mass flow rates of both the heat source fluid and the process fluid. The dynamic boiler model is analysed for linear and step charges of the entering fluid temperatures and flow rates. The heat source side tests show that

  15. Manipulation of the spin in single molecule magnets via Landau-Zener transitions

    Science.gov (United States)

    Palii, Andrew; Tsukerblat, Boris; Clemente-Juan, Juan M.; Gaita-Ariño, Alejandro; Coronado, Eugenio

    2011-11-01

    We theoretically investigate the effects of a magnetic pulse on a single-molecule magnet (SMM) initially magnetized by a dc field along the easy axis of magnetization. In the Landau-Zener (LZ) scheme, it is shown that the final spin state is a function of the shape and duration of the pulse, conditioned by the decoherence time of the SMM. In the case of coherent tunneling, the asymmetric pulses are shown to reverse the direction of the magnetization, while the symmetric pulses can only decrease the value of the initial magnetization. It is also demonstrated that the application of an external variable dc field in the hard plane of magnetization provides the possibility to tune the resulting magnetization due to quantum interference effects. The results and the conditions for the observation of the pulse-triggered LZ transitions are illustrated by the application of the proposed scheme to the well-studied single-molecule magnet Fe8. To put the results into perspective, some potential applications of SMMs experiencing pulse-induced LZ transitions, such as switching devices and qubits, are discussed.

  16. seniority changing transitions in yrast states and systematics of Sn ...

    Indian Academy of Sciences (India)

    Bhoomika Maheshwari

    2017-10-26

    Oct 26, 2017 ... 1 states; Sn isotopes; generalized seniority; odd-tensor E3 transitions; shell model. PACS Nos 23.20.Js; 27.60.+j; 21.60.Cs. 1. Introduction. Symmetries in physics play a fundamental role in the theoretical description of a wide range of phenomena and are particularly useful in systematizing the prop-.

  17. Tracking the embryonic stem cell transition from ground state pluripotency

    NARCIS (Netherlands)

    Kalkan, T.; Olova, N.; Roode, M.; Mulas, C.; Lee, H.J.; Nett, I.; Marks, H.; Walker, R.; Stunnenberg, H.; Lilley, K.S.; Nichols, J.; Reik, W.; Bertone, P.; Smith, A.

    2017-01-01

    Mouse embryonic stem (ES) cells are locked into self-renewal by shielding from inductive cues. Release from this ground state in minimal conditions offers a system for delineating developmental progression from naive pluripotency. Here we examined the initial transition process. The ES cell

  18. Religion, state, society and identity in transition Ukraine

    NARCIS (Netherlands)

    van der Laarse, R.; Cherenkov, M.N.; Proshak, V.V.; Mykhalchuk, T.

    2015-01-01

    BookCover Religion, state, society and identity in transition Ukraine Rob van der Laarse, Mykhailo N. Cherenkov, Vitaliy V. Proshak, and Tetiana Mykhalchuk, eds. Pages: 800 pages Shipping Weight: 1000 gram Published: 11-2015 Publisher: WLP Language: US ISBN (softcover) : 9789462402652 Product

  19. Phase transitions of single polymer chains and of polymer solutions: insights from Monte Carlo simulations

    International Nuclear Information System (INIS)

    Binder, K; Paul, W; Strauch, T; Rampf, F; Ivanov, V; Luettmer-Strathmann, J

    2008-01-01

    The statistical mechanics of flexible and semiflexible macromolecules is distinct from that of small molecule systems, since the thermodynamic limit can also be approached when the number of (effective) monomers of a single chain (realizable by a polymer solution in the dilute limit) is approaching infinity. One can introduce effective attractive interactions into a simulation model for a single chain such that a swollen coil contracts when the temperature is reduced, until excluded volume interactions are effectively canceled by attractive forces, and the chain conformation becomes almost Gaussian at the theta point. This state corresponds to a tricritical point, as the renormalization group theory shows. Below the theta temperature a fluid globule is predicted (at nonzero concentration then phase separation between dilute and semidilute solutions occurs), while at still lower temperature a transition to a solid phase (crystal or glass) occurs. Monte Carlo simulations have shown, however, that the fluid globule phase may become suppressed, when the range of the effective attractive forces becomes too short, with the result that a direct (ultimately first-order) transition from the swollen coil to the solid occurs. This behavior is analogous to the behavior of colloidal particles with a very short range of attractive forces, where liquid-vapor-type phase separation may be suppressed. Analogous first-order transitions from swollen coils to dense rodlike or toroidal structures occur for semiflexible polymers. Finally, the modifications of the behavior discussed when the polymers are adsorbed at surfaces are also mentioned, and possible relations to wetting behavior of polymer solutions are addressed.

  20. Single crystal particles of a mesoporous mixed transition metal oxide with a wormhole structure.

    Science.gov (United States)

    Lee, B; Lu, D; Kondo, J N; Domen, K

    2001-10-21

    A new type of mesoporous mixed transition metal oxide of Nb and Ta (NbTa-TIT-1) has been prepared through a two-step calcination, which consists of single crystal particles with wormhole mesoporous structure.

  1. Thermodynamics of single polyethylene and polybutylene glycols with hydrogen-bonding ends: A transition from looped to open conformations

    Science.gov (United States)

    Lee, Eunsang; Paul, Wolfgang

    2018-02-01

    A variety of linear polymer precursors with hydrogen bonding motifs at both ends enable us to design supramolecular polymer systems with tailored macroscopic properties including self-healing. In this study, we investigate thermodynamic properties of single polyethylene and polybutylene glycols with hydrogen bonding motifs. In this context, we first build a coarse-grained model of building blocks of the supramolecular polymer system based on all-atom molecular structures. The density of states of the single precursor is obtained using the stochastic approximation Monte Carlo method. Constructing canonical partition functions from the density of states, we find the transition from looped to open conformations at transition temperatures which are non-monotonously changing with an increasing degree of polymerization due to the competition between chain stiffness and loop-forming entropy penalty. In the complete range of chain length under investigation, a coexistence of the looped and open morphologies at the transition temperature is shown regardless of whether the transition is first-order-like or continuous. Polyethylene and polybutylene glycols show similar behavior in all the thermodynamic properties but the transition temperature of the more flexible polybutylene glycol is shown to change more gradually.

  2. Potential of electric quadrupole transitions in radium isotopes for single-ion optical frequency standards

    NARCIS (Netherlands)

    Versolato, O. O.; Wansbeek, L. W.; Jungmann, K.; Timmermans, R. G. E.; Willmann, L.; Wilschut, H. W.

    2011-01-01

    We explore the potential of the electric quadrupole transitions 7s (2)S(1/2)-(6)d (2)D(3/2), 6d (2)D(5/2) in radium isotopes as single-ion optical frequency standards. The frequency shifts of the clock transitions due to external fields and the corresponding uncertainties are calculated. Several

  3. Electronic and optical properties of vacancy defects in single-layer transition metal dichalcogenides

    Science.gov (United States)

    Khan, M. A.; Erementchouk, Mikhail; Hendrickson, Joshua; Leuenberger, Michael N.

    2017-06-01

    A detailed first-principles study has been performed to evaluate the electronic and optical properties of single-layer (SL) transition metal dichalcogenides (TMDCs) (M X 2 ; M = transition metal such as Mo, W, and X = S, Se, Te), in the presence of vacancy defects (VDs). Defects usually play an important role in tailoring electronic, optical, and magnetic properties of semiconductors. We consider three types of VDs in SL TMDCs: (i) X vacancy, (ii) X2 vacancy, and (iii) M vacancy. We show that VDs lead to localized defect states (LDS) in the band structure, which in turn gives rise to sharp transitions in in-plane and out-of-plane optical susceptibilities, χ∥ and χ⊥. The effects of spin-orbit coupling (SOC) are also considered. We find that SOC splitting in LDS is directly related to the atomic number of the transition metal atoms. Apart from electronic and optical properties we also find magnetic signatures (local magnetic moment of ˜μB ) in MoSe2 in the presence of the Mo vacancy, which breaks the time-reversal symmetry and therefore lifts the Kramers degeneracy. We show that a simple qualitative tight-binding model (TBM), involving only the hopping between atoms surrounding the vacancy with an on-site SOC term, is sufficient to capture the essential features of LDS. In addition, the existence of the LDS can be understood from the solution of the two-dimensional Dirac Hamiltonian by employing infinite mass boundary conditions. In order to provide a clear description of the optical absorption spectra, we use group theory to derive the optical selection rules between LDS for both χ∥ and χ⊥.

  4. Sample Size Induced Brittle-to-Ductile Transition of Single-Crystal Aluminum Nitride

    Science.gov (United States)

    2015-08-01

    Aluminum Nitride by GA Gazonas and JW McCauley Weapons and Materials Research Directorate, ARL JJ Guo, KM Reddy, A Hirata, T Fujita, and MW Chen...Sample Size Induced Brittle-to-Ductile Transition of Single-Crystal Aluminum Nitride 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT...their microscopic structure. In this study, we report a size induced brittle-to-ductile transition in single-crystal aluminum nitride (AlN). When the

  5. Ensemble and single-molecule studies on fluorescence quenching in transition metal bipyridine-complexes.

    Directory of Open Access Journals (Sweden)

    Dominik Brox

    Full Text Available Beyond their use in analytical chemistry fluorescent probes continuously gain importance because of recent applications of single-molecule fluorescence spectroscopy to monitor elementary reaction steps. In this context, we characterized quenching of a fluorescent probe by different metal ions with fluorescence spectroscopy in the bulk and at the single-molecule level. We apply a quantitative model to explain deviations from existing standard models for fluorescence quenching. The model is based on a reversible transition from a bright to a dim state upon binding of the metal ion. We use the model to estimate the stability constants of complexes with different metal ions and the change of the relative quantum yield of different reporter dye labels. We found ensemble data to agree widely with results from single-molecule experiments. Our data indicates a mechanism involving close molecular contact of dye and quenching moiety which we also found in molecular dynamics simulations. We close the manuscript with a discussion of possible mechanisms based on Förster distances and electrochemical potentials which renders photo-induced electron transfer to be more likely than Förster resonance energy transfer.

  6. EPA FRS Facilities State Single File CSV Download

    Science.gov (United States)

    This page provides state comma separated value (CSV) files containing key information of all facilities and sites within the Facility Registry System (FRS). Each state zip file contains a single CSV file of key facility-level information.

  7. Cooperative single-photon subradiant states

    Science.gov (United States)

    Jen, H. H.; Chang, M.-S.; Chen, Y.-C.

    2016-07-01

    We propose a set of subradiant states which can be prepared and detected in a one-dimensional optical lattice. We find that the decay rates are highly dependent on the spatial phases imprinted on the atomic chain, which allows systematic investigations of the subradiance in fluorescence experiments. The time evolution of these states can have a long decay time where up to 100 ms of lifetime is predicted for 100 atoms. They can also show decayed Rabi-like oscillations with a beating frequency determined by the difference of the cooperative Lamb shift in the subspace. Experimental requirements are also discussed for practical implementation of the subradiant states. Our proposal provides a scheme for quantum storage of photons in arrays of two-level atoms through the preparation and detection of subradiant states, which offers opportunities for quantum many-body state preparation and quantum information processing in optical lattices.

  8. Antiferrodistortive phase transitions and ground state of PZT ceramics

    International Nuclear Information System (INIS)

    Pandey, Dhananjai

    2013-01-01

    The ground state of the technologically important Pb(Zr x Ti (1-x) )O 3 , commonly known as PZT, ceramics is currently under intense debate. The phase diagram of this material shows a morphotropic phase boundary (MPB) for x∼0.52 at 300K, across which a composition induced structural phase transition occurs leading to maximization of the piezoelectric properties. In search for the true ground state of the PZT in the MPB region, Beatrix Noheda and coworkers first discovered a phase transition from tetragonal (space group P4mm) to an M A type monoclinic phase (space group Cm) at low temperatures for x=0.52. Soon afterwards, we discovered yet another low temperature phase transition for the same composition in which the M A type (Cm) monoclinic phase transforms to another monoclinic phase with Cc space group. We have shown that the Cm to Cc phase transition is an antiferrodistortive (AFD) transition involving tilting of oxygen octahedra leading to unit cell doubling and causing appearance of superlattice reflections which are observable in the electron and neutron diffraction patterns only and not in the XRD patterns, as a result of which Noheda and coworkers missed the Cc phase in their synchrotron XRD studies at low temperatures. Our findings were confirmed by leading groups using neutron, TEM, Raman and high pressure diffraction studies. The first principles calculations also confirmed that the true ground state of PZT in the MPB region has Cc space group. However, in the last couple of years, the Cc space group of the ground state has become controversial with an alternative proposal of R3c as the space group of the ground state phase which is proposed to coexist with the metastable Cm phase. In order to resolve this controversy, we recently revisited the issue using pure PZT and 6% Sr 2+ substituted PZT, the latter samples show larger tilt angle on account of the reduction in the average cationic radius at the Pb 2+ site. Using high wavelength neutrons and high

  9. Physiologic Measures of Animal Stress during Transitional States of Consciousness

    Directory of Open Access Journals (Sweden)

    Robert E. Meyer

    2015-08-01

    Full Text Available Determination of the humaneness of methods used to produce unconsciousness in animals, whether for anesthesia, euthanasia, humane slaughter, or depopulation, relies on our ability to assess stress, pain, and consciousness within the contexts of method and application. Determining the subjective experience of animals during transitional states of consciousness, however, can be quite difficult; further, loss of consciousness with different agents or methods may occur at substantially different rates. Stress and distress may manifest behaviorally (e.g., overt escape behaviors, approach-avoidance preferences [aversion] or physiologically (e.g., movement, vocalization, changes in electroencephalographic activity, heart rate, sympathetic nervous system [SNS] activity, hypothalamic-pituitary axis [HPA] activity, such that a one-size-fits-all approach cannot be easily applied to evaluate methods or determine specific species applications. The purpose of this review is to discuss methods of evaluating stress in animals using physiologic methods, with emphasis on the transition between the conscious and unconscious states.

  10. Communication: Electronic flux induced by crossing the transition state

    Science.gov (United States)

    Jia, Dongming; Manz, Jörn; Yang, Yonggang

    2018-01-01

    We present a new effect of chemical reactions, e.g., isomerizations, that occurs when the reactants pass along the transition state, on the way to products. It is based on the well-known fact that at the transition state, the electronic structure of one isomer changes to the other. We discover that this switch of electronic structure causes a strong electronic flux that is well distinguishable from the usual flux of electrons that travel with the nuclei. As a simple but clear example, the effect is demonstrated here for bond length isomerization of Na2 (21Σu+), with adiabatic crossing the barrier between the inner and outer wells of the double minimum potential that support different "Rydberg" and "ionic" type electronic structures, respectively.

  11. Optimal control of transitions between nonequilibrium steady states.

    Directory of Open Access Journals (Sweden)

    Patrick R Zulkowski

    Full Text Available Biological systems fundamentally exist out of equilibrium in order to preserve organized structures and processes. Many changing cellular conditions can be represented as transitions between nonequilibrium steady states, and organisms have an interest in optimizing such transitions. Using the Hatano-Sasa Y-value, we extend a recently developed geometrical framework for determining optimal protocols so that it can be applied to systems driven from nonequilibrium steady states. We calculate and numerically verify optimal protocols for a colloidal particle dragged through solution by a translating optical trap with two controllable parameters. We offer experimental predictions, specifically that optimal protocols are significantly less costly than naive ones. Optimal protocols similar to these may ultimately point to design principles for biological energy transduction systems and guide the design of artificial molecular machines.

  12. Electromagnetic transitions between states satisfying free-boundary conditions

    International Nuclear Information System (INIS)

    Nikolopoulos, L. A. A.

    2006-01-01

    We address the problem of calculating electromagnetic transition matrix elements between states of a particle in spherically symmetrical potentials with no assumed boundary conditions at finite distance (free-boundary-condition method). For this, the Schroedinger equation is solved in a finite box of radius R and bound and continuum states, appropriately normalized, are numerically represented, through a variational finite-basis-set (B-spline) approach. The equivalence between the three transition operator forms (length, velocity, acceleration), within this approach, is discussed, and bound-continuum and continuum-continuum matrix elements are calculated in all three gauges. Results for the strong electromagnetic radiation of hydrogen are presented through the calculation of two-photon ionization cross sections and photoelectron angular distributions. It is demonstrated that the present approach is well suited for the calculation of multiphoton transitions when ionization in the continuum is allowed (above-threshold ionization). With the free-boundary-condition method complete control over the density of scattering states is feasible and, as the result of that, the degeneracy in the continuum between partial waves is preserved

  13. Reliable Transition State Searches Integrated with the Growing String Method.

    Science.gov (United States)

    Zimmerman, Paul

    2013-07-09

    The growing string method (GSM) is highly useful for locating reaction paths connecting two molecular intermediates. GSM has often been used in a two-step procedure to locate exact transition states (TS), where GSM creates a quality initial structure for a local TS search. This procedure and others like it, however, do not always converge to the desired transition state because the local search is sensitive to the quality of the initial guess. This article describes an integrated technique for simultaneous reaction path and exact transition state search. This is achieved by implementing an eigenvector following optimization algorithm in internal coordinates with Hessian update techniques. After partial convergence of the string, an exact saddle point search begins under the constraint that the maximized eigenmode of the TS node Hessian has significant overlap with the string tangent near the TS. Subsequent optimization maintains connectivity of the string to the TS as well as locks in the TS direction, all but eliminating the possibility that the local search leads to the wrong TS. To verify the robustness of this approach, reaction paths and TSs are found for a benchmark set of more than 100 elementary reactions.

  14. The effect of transitional particles driven by single wave

    International Nuclear Information System (INIS)

    Qiu Yunqing; Xia Mengfen

    1987-05-01

    The unperturbed separatrix crossing driven by a single wave in a tokamak plasma is discussed. The separatrix crossing is followed by a mixing process, and a small-scale structure occurs in the distribution function in h-ψ plane. The separatrix crossing is a convective process in h-ψ plane, and there is a definite crossing channel. The convective flux and the net flux in h-direction are calculated. The separatrix crossing is accompanied by a radial flux, which is composed of a directional flux and a diffusion flux. (author). 7 refs, 6 figs

  15. Joint Remote State Preparation of a Single-Atom Qubit State via a GHZ Entangled State

    Science.gov (United States)

    Xiao, Xiao-Qi; Yao, Fengwei; Lin, Xiaochen; Gong, Lihua

    2018-04-01

    We proposed a physical protocol for the joint remote preparation of a single-atom qubit state via a three-atom entangled GHZ-type state previously shared by the two senders and one receiver. Only rotation operations of single-atom, which can be achieved though the resonant interaction between the two-level atom and the classical field, are required in the scheme. It shows that the splitting way of the classical information of the secret qubit not only determines the success of reconstruction of the secret qubit, but also influences the operations of the senders.

  16. Role of entropy and structural parameters in the spin-state transition of LaCoO3

    Science.gov (United States)

    Chakrabarti, Bismayan; Birol, Turan; Haule, Kristjan

    2017-11-01

    The spin-state transition in LaCoO3 has eluded description for decades despite concerted theoretical and experimental effort. In this study, we approach this problem using fully charge self-consistent density functional theory + embedded dynamical mean field theory (DFT+DMFT). We show from first principles that LaCoO3 cannot be described by a single, pure spin state at any temperature. Instead, we observe a gradual change in the population of higher-spin multiplets with increasing temperature, with the high-spin multiplets being excited at the onset of the spin-state transition followed by the intermediate-spin multiplets being excited at the metal-insulator-transition temperature. We explicitly elucidate the critical role of lattice expansion and oxygen octahedral rotations in the spin-state transition. We also reproduce, from first principles, that the spin-state transition and the metal-insulator transition in LaCoO3 occur at different temperature scales. In addition, our results shed light on the importance of electronic entropy in driving the spin-state transition, which has so far been ignored in all first-principles studies of this material.

  17. The influence of elastic subsystem on phase transitions in ferromagnets with competitive exchange and single-ion anisotropies

    International Nuclear Information System (INIS)

    Freedman, Yu.A.; Klevets, F.N.; Matunin, D.A.

    2006-01-01

    The influence of planar and bulk elastic interactions on the phase states of an ultrathin ferromagnetic film with anisotropic exchange interaction is investigated for different relationships among the material constants. It is shown that when the elastic interactions, with competing exchange and single-ion anisotropies, and the magnetic dipole interaction are taken into account, a cascade of phase transitions appears. Furthermore, taking the 'planar' elastic interaction into account leads to realization of an additional phase, with an easy axis in the film plane. This state is absent in the case of a bulk elastic subsystem

  18. Calculation of the state-to-state S-matrix for tetra-atomic reactions with transition-state wave packets: H₂/D₂ + OH → H/D + H₂O/HOD.

    Science.gov (United States)

    Zhao, Bin; Sun, Zhigang; Guo, Hua

    2014-10-21

    This work is concerned with the calculation of state-to-state S-matrix elements for four-atom reactions using a recently proposed method based on the quantum transition-state theory. In this approach, the S-matrix elements are computed from the thermal flux cross-correlation functions obtained in both the reactant and product arrangement channels. Since transition-state wave packets are propagated with only single arrangement channels, the bases/grids required are significantly smaller than those needed in state-to-state approaches based on a single set of scattering coordinates. Furthermore, the propagation of multiple transition-state wave packets can be carried out in parallel. This method is demonstrated for the H2/D2 + OH → H/D + H2O/HOD reactions (J = 0) and the reaction probabilities are in excellent agreement with benchmark results.

  19. Polymorphic transitions in single crystals: A new molecular dynamics method

    Energy Technology Data Exchange (ETDEWEB)

    Parrinello, M.; Rahman, A.

    1981-12-01

    A new Lagrangian formulation is introduced. It can be used to make molecular dynamics (MD) calculations on systems under the most general, externally applied, conditions of stress. In this formulation the MD cell shape and size can change according to dynamical equations given by this Lagrangian. This new MD technique is well suited to the study of structural transformations in solids under external stress and at finite temperature. As an example of the use of this technique we show how a single crystal of Ni behaves under uniform uniaxial compressive and tensile loads. This work confirms some of the results of static (i.e., zero temperature) calculations reported in the literature. We also show that some results regarding the stress-strain relation obtained by static calculations are invalid at finite temperature. We find that, under compressive loading, our model of Ni shows a bifurcation in its stress-strain relation; this bifurcation provides a link in configuration space between cubic and hexagonal close packing. It is suggested that such a transformation could perhaps be observed experimentally under extreme conditions of shock.

  20. Design of biomimetic catalysts by molecular imprinting in synthetic polymers: the role of transition state stabilization.

    Science.gov (United States)

    Wulff, Günter; Liu, Junqiu

    2012-02-21

    electrostatic stabilization for the transition state through the amidinium group as well as a synergism of transition state recognition and metal ion catalysis. The result was an excellent catalyst for carbonate hydrolysis. These enzyme mimics represent the most active catalysts ever prepared through the molecular imprinting strategy. Their catalytic activity, catalytic efficiency, and catalytic proficiency clearly surpass those of the corresponding catalytic antibodies. The active structures in natural enzymes evolve within soluble proteins, typically by the refining of the folding of one polypeptide chain. To incorporate these characteristics into synthetic polymers, we used the concept of transition state stabilization to develop soluble, nanosized carboxypeptidase A models using a new polymerization method we term the "post-dilution polymerization method". With this methodology, we were able to prepare soluble, highly cross-linked, single-molecule nanoparticles. These particles have controlled molecular weights (39 kDa, for example) and, on average, one catalytically active site per particle. Our strategies have made it possible to obtain efficient new enzyme models and further advance the structural and functional analogy with natural enzymes. Moreover, this bioinspired design based on molecular imprinting in synthetic polymers offers further support for the concept of transition state stabilization in catalysis.

  1. Effects of single particle on shape phase transitions and phase coexistence in odd-even nuclei

    Science.gov (United States)

    Yu, Xiang-Ru; Hu, Jing; Li, Xiao-Xue; An, Si-Yu; Zhang, Yu

    2018-02-01

    A classical analysis of shape phase transitions and phase coexistence in odd-even nuclei has been performed in the framework of the interacting boson-fermion model. The results indicate that the effects of a single particle may influence different types of transitions in different ways. Especially, it is revealed that phase coexistence can clearly emerge in the critical region and thus be taken as a indicator of the shape phase transitions in odd-even nuclei. Supported by National Natural Science Foundation of China (11375005)

  2. Transition-state structures for enzymatic and alkaline phosphotriester hydrolysis

    International Nuclear Information System (INIS)

    Caldwell, S.R.; Raushel, F.M.; Weiss, P.M.; Cleland, W.W.

    1991-01-01

    The primary and secondary 18 O isotope effects for the alkaline (KOH) and enzymatic (phosphotriesterase) hydrolysis of two phosphotriesters, O,O-diethyl p-nitrophenyl phosphate (I) and O,O-diethyl O-(4-carbamoylphenyl) phosphate (II), are consistent with an associative mechanism with significant changes in bond order to both the phosphoryl and phenolic leaving group oxygens in the transition state. The synthesis of [ 15 N, phosphoryl- 18 O]-,[ 15 N, phenolic- 18 O]-, and [ 15 N]-O,O-diethyl p-nitrophenyl phosphate and O,O-diethyl O-(4-carbamoylphenyl)phosphate is described. The primary and secondary 18 O isotope effects for the alkaline hydrolysis of compound I are 1.0060 and 1.0063 ± 0.0001, whereas for compound II they are 1.027±0.002 and 1.025 ± 0.002, respectively. These isotope effects are consistent with the rate-limiting addition of hydroxide and provide evidence for a S N 2-like transition state with the absence of a stable phosphorane intermediate. For the enzymatic hydrolysis of compound I, the primary and secondary 18 O isotope effects are very small, 1.0020 and 1.0021±0.0004, respectively, and indicate that the chemical step in the enzymatic mechanism is not rate-limiting. The 18 O isotope effects for the enzymatic hydrolysis of compound II are 1.036±0.001 and 1.0181±0.0007, respectively, and are comparable in magnitude to the isotope effects for alkaline hydrolysis, suggesting that the chemical step is rate-limiting. The relative magnitude of the primary 18 O isotope effects for the alkaline and enzymatic hydrolysis of compound II reflect a transition state that is more progressed for the enzymatic reaction

  3. Chaotic state to self-organized critical state transition of serrated flow dynamics during brittle-to-ductile transition in metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Wang, C.; Wang, W. H.; Bai, H. Y., E-mail: hybai@aphy.iphy.ac.cn [Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Sun, B. A. [Centre for Advanced Structural Materials, Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Kowloon Tong, Kowloon (Hong Kong)

    2016-02-07

    We study serrated flow dynamics during brittle-to-ductile transition induced by tuning the sample aspect ratio in a Zr-based metallic glass. The statistical analysis reveals that the serrated flow dynamics transforms from a chaotic state characterized by Gaussian-distribution serrations corresponding to stick-slip motion of randomly generated and uncorrelated single shear band and brittle behavior, into a self-organized critical state featured by intermittent scale-free distribution of shear avalanches corresponding to a collective motion of multiple shear bands and ductile behavior. The correlation found between serrated flow dynamics and plastic deformation might shed light on the plastic deformation dynamic and mechanism in metallic glasses.

  4. Single Pixel, Single Band Microstrip Antenna for Sub-Millimeter Wavelength Detection Using Transition Edge Superconducting Bolometric Receivers

    Science.gov (United States)

    Hunt, Cynthia; Bock, Jamie J.; Day, Peter K.; Goldin, Alexey; Lange, Andrew E.; Leduc, Henry G.; Vayonakis, Anastasios; Zmuidzinas, Jonas

    We are developing a single pixel antenna coupled bolometric detector as a precursor to the SAMBA (Superconducting Antenna-coupled Multi-frequency Bolometric Array) instrument. Our device consists of a dual slot microstrip antenna coupled to an Al/Ti/Au voltage-biased transition edge superconducting bolometer (TES). The coupling architecture involves propagating the signal along superconducting microstrip lines and terminating the lines at a normal metal resistor on a thermally isolated island. The device, which is inherently polarization sensitive, is optimized to for 100GHz band measurements, ideal for future implementation as an astronomical sub-millimeter instrument. We will present recent tests of these single pixel detectors.

  5. Finite-state transition system analysis of disturbed foundation stiffness

    DEFF Research Database (Denmark)

    Sabaliauskas, Tomas; Ibsen, Lars Bo

    2018-01-01

    Foundations erected in sand can become disturbed during dynamic loading, as sand stiffness can both increase and decrease episodically. Paradigms outside geotechnics analyze similar problems as finite-state transition systems. Therefore, patterns governing disturbed foundation stiffness change......, the unconventional analysis technique delivers substantial descriptive and predictive power. To demonstrate the utility, stiffness of a foundation prototype is manipulated: during real-life, real-time testing, the initial stiffness path is disturbed and recovered 5 times in one loading sequence. Thus, the "memory...

  6. Solid State Recrystallization of Single Crystal Ce:LSO Scintillator Crystals for High Resolution Detectors

    Science.gov (United States)

    2012-06-01

    Advances in our knowledge of scintillation and semiconductor materials, plastics , organics, glass, synthesized nano-crystal fabrics and fluids as...are few electron traps leading to non-radioactive transitions that quench the primary scintillation mechanisms. In addition the host lattice has a...TR-10-69 Solid State Recrystallization of Single Crystal Ce:LSO Scintillator Crystals for High Resolution Detectors Approved for public release

  7. Toward quantum state tomography of a single polariton state of an atomic ensemble

    DEFF Research Database (Denmark)

    Christensen, S.L.; Béguin, J.B.; Sørensen, H.L.

    2013-01-01

    We present a proposal and a feasibility study for the creation and quantum state tomography of a single polariton state of an atomic ensemble. The collective non-classical and non-Gaussian state of the ensemble is generated by detection of a single forward-scattered photon. The state is subsequen...... the feasibility of the proposed method for the detection of a non-classical and non-Gaussian state of the mesoscopic atomic ensemble. This work represents the first attempt at hybrid discrete-continuous variable quantum state processing with atomic memories.......We present a proposal and a feasibility study for the creation and quantum state tomography of a single polariton state of an atomic ensemble. The collective non-classical and non-Gaussian state of the ensemble is generated by detection of a single forward-scattered photon. The state...

  8. Control and Coherence of the Optical Transition of Single Nitrogen Vacancy Centers in Diamond

    NARCIS (Netherlands)

    Robledo, L.M.; Bernien, H.; Van Weperen, I.; Hanson, R.

    2010-01-01

    We demonstrate coherent control of the optical transition of single nitrogen-vacancy defect centers in diamond. On applying short resonant laser pulses, we observe optical Rabi oscillations with a half period as short as 1 ns, an order of magnitude shorter than the spontaneous emission time. By

  9. Single Cigarette Sales: State Differences in FDA Advertising and Labeling Violations, 2014, United States.

    Science.gov (United States)

    Baker, Hannah M; Lee, Joseph G L; Ranney, Leah M; Goldstein, Adam O

    2016-02-01

    Single cigarettes, which are sold without warning labels and often evade taxes, can serve as a gateway for youth smoking. The Family Smoking Prevention and Tobacco Control Act of 2009 gives the US Food and Drug Administration (FDA) authority to regulate the manufacture, distribution, and marketing of tobacco products, including prohibiting the sale of single cigarettes. To enforce these regulations, the FDA conducted over 335,661 inspections between 2010 and September 30, 2014, and allocated over $115 million toward state inspections contracts. To examine differences in single cigarette violations across states and determine if likely correlates of single cigarette sales predict single cigarette violations at the state level. Cross-sectional study of publicly available FDA warning letters from January 1 to July 31, 2014. All 50 states and the District of Columbia. Tobacco retailer inspections conducted by FDA (n = 33 543). State cigarette tax, youth smoking prevalence, poverty, and tobacco production. State proportion of FDA warning letters issued for single cigarette violations. There are striking differences in the number of single cigarette violations found by state, with 38 states producing no warning letters for selling single cigarettes even as state policymakers developed legislation to address retailer sales of single cigarettes. The state proportion of warning letters issued for single cigarettes is not predicted by state cigarette tax, youth smoking, poverty, or tobacco production, P = .12. Substantial, unexplained variation exists in violations of single cigarette sales among states. These data suggest the possibility of differences in implementation of FDA inspections and the need for stronger quality monitoring processes across states implementing FDA inspections. © The Author 2015. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  10. Single particle radiation between high spin states in /sup 147/Gd

    Energy Technology Data Exchange (ETDEWEB)

    Borggreen, J.; Sletten, G.; Bjoernholm, S.; Pedersen, J.; Del Zoppo, A.; Radford, D.C.; Janssens, R.V.F.; Chowdhury, P.; Emling, H.; Frekers, D.

    1987-05-04

    Transitions above the T/sub 1/2/=550 ns, 8.59 MeV isomer in /sup 147/Gd have been studied using the (/sup 30/Si, 5n) reaction. Results from ..gamma gamma.. coincidence, angular distribution and recoil distance measurements are combined to establish a level scheme up to 16.9 MeV and I approx. = 79/2. Single particle configurations are assigned on the basis of the deformed independent particle model. The single particle nature of the highest spin states and the apparent lack of collectivity is discussed.

  11. Single-Column Model Simulations of Subtropical Marine Boundary-Layer Cloud Transitions Under Weakening Inversions: SCM SIMULATIONS OF CLOUD TRANSITIONS

    Energy Technology Data Exchange (ETDEWEB)

    Neggers, R. A. J. [Institute for Geophysics and Meteorology, Department of Geosciences, University of Cologne, Cologne Germany; Royal Netherlands Meteorological Institute, De Bilt The Netherlands; Ackerman, A. S. [NASA Goddard Institute for Space Studies, New York NY USA; Angevine, W. M. [CIRES, University of Colorado, Boulder CO USA; NOAA Earth System Research Laboratory, Boulder CO USA; Bazile, E. [Météo France/CNRM, Toulouse France; Beau, I. [Météo France/ENM, Toulouse France; Blossey, P. N. [Department of Atmospheric Sciences, University of Washington, Seattle WA USA; Boutle, I. A. [Met Office, Exeter UK; de Bruijn, C. [Royal Netherlands Meteorological Institute, De Bilt The Netherlands; Cheng, A. [NOAA Center for Weather and Climate Prediction, Environmental Modeling Center, College Park MD USA; van der Dussen, J. [Department of Geoscience and Remote Sensing, Delft University of Technology, Delft The Netherlands; Fletcher, J. [Department of Atmospheric Sciences, University of Washington, Seattle WA USA; University of Leeds, Leeds UK; Dal Gesso, S. [Institute for Geophysics and Meteorology, Department of Geosciences, University of Cologne, Cologne Germany; Royal Netherlands Meteorological Institute, De Bilt The Netherlands; Jam, A. [Météo-France/CNRM & CNRS/IPSL/LMD, Toulouse France; Kawai, H. [Meteorological Research Institute, Climate Research Department, Japan Meteorological Agency, Tsukuba Japan; Cheedela, S. K. [Department of Atmosphere in the Earth System, Max-Planck Institut für Meteorologie, Hamburg Germany; Larson, V. E. [Department of Mathematical Sciences, University of Wisconsin-Milwaukee, Milwaukee WI USA; Lefebvre, M. -P. [Météo-France/CNRM & CNRS/IPSL/LMD, Toulouse France; Lock, A. P. [Met Office, Exeter UK; Meyer, N. R. [Department of Mathematical Sciences, University of Wisconsin-Milwaukee, Milwaukee WI USA; de Roode, S. R. [Department of Geoscience and Remote Sensing, Delft University of Technology, Delft The Netherlands; de Rooy, W. [Royal Netherlands Meteorological Institute, De Bilt The Netherlands; Sandu, I. [Section of Physical Aspects, European Centre for Medium-Range Weather Forecasts, Reading UK; Xiao, H. [University of California at Los Angeles, Los Angeles CA USA; Pacific Northwest National Laboratory, Richland WA USA; Xu, K. -M. [NASA Langley Research Centre, Hampton VI USA

    2017-10-01

    Results are presented of the GASS/EUCLIPSE single-column model inter-comparison study on the subtropical marine low-level cloud transition. A central goal is to establish the performance of state-of-the-art boundary-layer schemes for weather and climate mod- els for this cloud regime, using large-eddy simulations of the same scenes as a reference. A novelty is that the comparison covers four different cases instead of one, in order to broaden the covered parameter space. Three cases are situated in the North-Eastern Pa- cific, while one reflects conditions in the North-Eastern Atlantic. A set of variables is considered that reflects key aspects of the transition process, making use of simple met- rics to establish the model performance. Using this method some longstanding problems in low level cloud representation are identified. Considerable spread exists among models concerning the cloud amount, its vertical structure and the associated impact on radia- tive transfer. The sign and amplitude of these biases differ somewhat per case, depending on how far the transition has progressed. After cloud breakup the ensemble median ex- hibits the well-known “too few too bright” problem. The boundary layer deepening rate and its state of decoupling are both underestimated, while the representation of the thin capping cloud layer appears complicated by a lack of vertical resolution. Encouragingly, some models are successful in representing the full set of variables, in particular the verti- cal structure and diurnal cycle of the cloud layer in transition. An intriguing result is that the median of the model ensemble performs best, inspiring a new approach in subgrid pa- rameterization.

  12. Transit Car Performance Comparison, State-of-the-Art Car vs. PATCO Transit Car, NYCTA R-46, MBTA Silverbirds

    Science.gov (United States)

    1978-02-01

    The first phase of this contract authorized the design, development, and demonstration of two State-Of-The-Art Cars (SOAC). This document reports on the gathering of comparative test data on existing in-service transit cars. The three transit cars se...

  13. Magnetic control of single transition metal doped MoS{sub 2} through H/F chemical decoration

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Sizhe [Hunan Provincial Key Laboratory of Thin Film Materials and Devices, School of Materials Science and Engineering, Xiangtan University, Xiangtan 411105 (China); He, Junjie [Faculty of Science, Charles University in Prague, 128 43 Prague 2 (Czech Republic); Zhou, Pan [Hunan Provincial Key Laboratory of Thin Film Materials and Devices, School of Materials Science and Engineering, Xiangtan University, Xiangtan 411105 (China); Sun, L.Z., E-mail: lzsun@xtu.edu.cn [Hunan Provincial Key Laboratory of Thin Film Materials and Devices, School of Materials Science and Engineering, Xiangtan University, Xiangtan 411105 (China)

    2017-01-15

    Using density function theory, we study the spin state control of transition metal doped MoS{sub 2} through H/F chemical decoration. The results indicate that the ground spin state of single TM (Mn, Fe, and Co) doped MoS{sub 2} is sensitive to its chemical environment. H/F chemical decoration on TM can effectively modulate their magnetic moment up to 1 μ{sub B}, especially for the Mn doped system, the F decoration will produce the system show “spin ON” to “spin OFF” transition. Interestingly, the H decoration will increase the magnetic moment of TM doped MoS{sub 2} with 1 μ{sub B}, however, the F decoration will reduce the magnetic moment of TM doped MoS{sub 2} with 1 μ{sub B}. Such modulation derives from the anti-bonding and bonding nature between TM and H/F atom, respectively. Our results may open a new route to apply TM doped MoS{sub 2} to multistate memory. - Highlights: • Spin state control of TM doped MoS2 through H/F chemical decoration. • “Spin ON” to “spin OFF” transition. • Anti-bonding and bonding nature between TM and H/F atom.

  14. Detection of individual spin transitions of a single proton confined in a cryogenic Penning trap

    Energy Technology Data Exchange (ETDEWEB)

    Kracke, Holger

    2013-02-27

    The presented experiment for the determination of the magnetic moment of the proton is based on the measurement of the ratio of cyclotron frequency and Larmor frequency of a single proton confined in a cryogenic double-Penning trap. In the course of this thesis, the simultaneous non-destructive measurement of two of the three eigenfrequencies of the proton in thermal equilibrium with corresponding detection systems was demonstrated, which reduces the measurement time of the cyclotron frequency by a factor of two. Furthermore, this thesis presents the first detection of individual spin transitions of a single proton, which allows for the determination of the Larmor frequency. The continuous Stern-Gerlach effect is utilized to couple the magnetic moment to the axial mode of the trapped proton by means of a magnetic bottle. Thus, a spin flip causes a jump of the axial frequency, which can be measured non-destructively with highly-sensitive detection systems. However, not only the spin momentum is coupled to the axial motion but also the angular momentum. Thus, the main experimental challenge is the elimination of energy fluctuations in the radial modes in order to maintain spin flip resolution. Due to systematic studies on the stability of the axial frequency and a complete revision of the experimental setup, this goal was achieved. The spin state of the proton can be determined with very high fidelity for the very first time. Thus, this thesis represents an important step towards a high-precision determination of the magnetic moment of the proton.

  15. Ground state and magnetic phase transitions of orthoferrite DyFeO3

    Science.gov (United States)

    Zhao, Z. Y.; Zhao, X.; Zhou, H. D.; Zhang, F. B.; Li, Q. J.; Fan, C.; Sun, X. F.; Li, X. G.

    2014-06-01

    Low-temperature thermal conductivity (κ), as well as magnetization (M) and electric polarization (P), of multiferroic orthoferrite DyFeO3 single crystals are studied with H ∥c. When the crystal is cooled in zero field, M, P, and κ all consistently exhibit irreversible magnetic-field dependencies. In particular, with 500 mK ultra-low-T (T mK) κ (H) shows a different irreversibility and there is only one transition when the field is swept both up and down. All the results indicate a complex low-T H-T phase diagram involving successive magnetic phase transitions of the Fe3+ spins. In particular, the ground state, obtained with cooling to sub-Kelvin temperatures in zero field, is found to be an unexplored phase.

  16. The quality of life of single mothers making the transition from welfare to work.

    Science.gov (United States)

    Cook, Kay; Davis, Elise; Smyth, Paul; McKenzie, Hayley

    2009-09-01

    This study examined the quality of life of single mothers making the mandatory transition from welfare to work. The Australian government purported that the benefits of making this transition would include higher incomes, better social participation, and improved wellbeing. It is currently unknown, however, how single mothers currently engaged in welfare to work programs evaluate their quality of life. Quality of life scores for 334 single mothers engaged in welfare to work in Australia were compared with normative data. Participants reported significantly lower quality of life scores than the general population for all quality of life domains, highlighting the need to carefully examine welfare to work policies to ensure they promote participants' quality of life.

  17. Using measures of single-cell physiology and physiological state to understand organismic aging.

    Science.gov (United States)

    Mendenhall, Alexander; Driscoll, Monica; Brent, Roger

    2016-02-01

    Genetically identical organisms in homogeneous environments have different lifespans and healthspans. These differences are often attributed to stochastic events, such as mutations and 'epimutations', changes in DNA methylation and chromatin that change gene function and expression. But work in the last 10 years has revealed differences in lifespan- and health-related phenotypes that are not caused by lasting changes in DNA or identified by modifications to DNA or chromatin. This work has demonstrated persistent differences in single-cell and whole-organism physiological states operationally defined by values of reporter gene signals in living cells. While some single-cell states, for example, responses to oxygen deprivation, were defined previously, others, such as a generally heightened ability to make proteins, were, revealed by direct experiment only recently, and are not well understood. Here, we review technical progress that promises to greatly increase the number of these measurable single-cell physiological variables and measureable states. We discuss concepts that facilitate use of single-cell measurements to provide insight into physiological states and state transitions. We assert that researchers will use this information to relate cell level physiological readouts to whole-organism outcomes, to stratify aging populations into groups based on different physiologies, to define biomarkers predictive of outcomes, and to shed light on the molecular processes that bring about different individual physiologies. For these reasons, quantitative study of single-cell physiological variables and state transitions should provide a valuable complement to genetic and molecular explanations of how organisms age. © 2015 The Authors. Aging Cell published by the Anatomical Society and John Wiley & Sons Ltd.

  18. Spin-state transition and phase separation in multi-orbital Hubbard model

    Science.gov (United States)

    Ishihara, Sumio; Suzuki, Ryo; Watanabe, Tsutomu

    2010-03-01

    Exotic phenomena in correlated electron systems are responsible for competition and cooperation between multi-electronic phases. In particular, in perovskite cobaltites, there is the spin-state degree of freedom, i.e., multiple spin states due to the different electron configurations in a single ion. The multiple spin states occur by changes in the carrier concentration, temperature and other parameters. In the lightly hole doped region between the low-spin band insulator (BI) and the high-spin (HS) ferromagnetic metallic (FM) states, several inhomogeneous features have been reported experimentally. We address the issues of the spin-state transition and the phase separation (PS) associated with this transition by analyzing the multi-orbital Hubbard model [1]. We examine the electronic structures in hole doped and undoped systems by the variational Monte-Carlo (VMC) method. We find that the electronic PS is realized between the nonmagnetic BI and the HS FM metal. We conclude that the different band widths play an essential role in the present electronic PS. [1] R. Suzuki, T. Watanabe, and S. Ishihara, Phys. Rev. B 80, 054410 (2009).

  19. Bound states of quarks and gluons and hadronic transitions

    International Nuclear Information System (INIS)

    Castro, Antonio Soares de.

    1990-05-01

    A potential which incorporates the concepts of confinement and asymptotic freedom, previously utilized in the description of the spectroscopy of mesons and baryons, is extended to the gluon sector. The mass spectroscopy of glueballs and hybrids is analyzed considering only pairwise potentials and massive constituent gluons. The mass spectrum of the color octet two-gluon system is adopted as a suitable description of the intermediate states of hadronic transitions, within the framework of the multipole expansion for quantum chromodynamics. The spin-dependent effects in the gluonium spectrum, associated with the Coulombian potential, are calculated through the inverted first Born approximation for the gluon-gluon scattering. (author). 102 refs, 1 fig, 13 tabs

  20. Mott transition and anomalous resistive state in the pyrochlore molybdates

    Science.gov (United States)

    Swain, Nyayabanta; Majumdar, Pinaki

    2017-07-01

    The rare-earth based pyrochlore molybdates involve orbitally degenerate electrons Hund's coupled to local moments. The large Hund's coupling promotes ferromagnetism, the superexchange between the local moments prefers antiferromagnetism, and Hubbard repulsion tries to open a Mott gap. The phase competition is tuned by the rare-earth ionic radius, decreasing which leads to change from a ferromagnetic metal to a spin disordered highly resistive ground state, and ultimately an “Anderson-Mott” insulator. We attempt a quantitative theory of the molybdates by studying their minimal model on a pyrochlore geometry, using a static auxiliary field based Monte Carlo. We establish a thermal phase diagram that closely corresponds to the experiments, predict the hitherto unexplored orbital correlations, quantify and explain the origin of the anomalous resistivity, and present dynamical properties across the metal-insulator transition.

  1. Raman scattering study of the structural phase transition in single crystal KDy(MoO4)2

    Science.gov (United States)

    Peschanskii, A. V.

    2017-11-01

    Raman scattering of light in single-crystal KDy(MoO4)2 is studied at frequencies of 3-1000 cm-1 for temperatures ranging from 2 to 300 K, including that of a structural phase transition of the cooperative Jahn-Teller type (TC ˜ 14.5 K). During the transition to the low-temperature phase, a series of additional phonon lines corresponding to the Ag, B1g, B2g, and B3g modes is observed which indicates a doubling of the unit cell during the phase transition. An analysis of the symmetry of the phonon modes shows that the low-temperature phase has a predominantly monoclinic symmetry with conservation of a second order axis along the crystallographic b direction, i.e., perpendicular to the layers. Excitations are discovered which correspond to low-energy electronic transitions between levels of the ground-state 6H15/2 multiplet of the Dy3+ ion, which is split in the crystal field with a C2 symmetry. In the vicinity of the first excited Kramers doublet of the Dy3+ ion in crystalline KDy(MoO4)2, the scattered spectrum contains four lines [16.5, 21.0, 24.9, and 29.1 cm-1 (2 K)] at low temperatures, instead of a single line [18.3 cm-1 (25 K)] above the phase transition temperature (14.5 K). This indicates the existence of four nonequivalent dysprosium ions in the low-temperature phase.

  2. Electronic state selectivity in dication-molecule single electron transfer reactions: NO(2+) + NO.

    Science.gov (United States)

    Parkes, Michael A; Lockyear, Jessica F; Schröder, Detlef; Roithová, Jana; Price, Stephen D

    2011-11-07

    The single-electron transfer reaction between NO(2+) and NO, which initially forms a pair of NO(+) ions, has been studied using a position-sensitive coincidence technique. The reactivity in this class of collision system, which involves the interaction of a dication with its neutral precursor, provides a sensitive test of recent ideas concerning electronic state selectivity in dicationic single-electron transfer reactions. In stark contrast to the recently observed single-electron transfer reactivity in the analogous CO(2)(2+)/CO(2) and O(2)(2+)/O(2) collision systems, electron transfer between NO(2+) and NO generates two product NO(+) ions which behave in an identical manner, whether the ions are formed from NO(2+) or NO. This observed behaviour is in excellent accord with the recently proposed rationalization of the state selectivity in dication-molecule SET reactions using simple propensity rules involving one-electron transitions. This journal is © the Owner Societies 2011

  3. Learning transitive verbs from single-word verbs in the input by young children acquiring English.

    Science.gov (United States)

    Ninio, Anat

    2016-09-01

    The environmental context of verbs addressed by adults to young children is claimed to be uninformative regarding the verbs' meaning, yielding the Syntactic Bootstrapping Hypothesis that, for verb learning, full sentences are needed to demonstrate the semantic arguments of verbs. However, reanalysis of Gleitman's (1990) original data regarding input to a blind child revealed the context of single-word parental verbs to be more transparent than that of sentences. We tested the hypothesis that English-speaking children learn their early verbs from parents' single-word utterances. Distribution of single-word transitive verbs produced by a large sample of young children was strongly predicted by the relative token frequency of verbs in parental single-word utterances, but multiword sentences had no predictive value. Analysis of the interactive context showed that objects of verbs are retrievable by pragmatic inference, as is the meaning of the verbs. Single-word input appears optimal for learning an initial vocabulary of verbs.

  4. Phase transition in cadmium sulfide single crystals shocked along the c axis

    International Nuclear Information System (INIS)

    Tang, Z.P.; Gupta, Y.M.

    1997-01-01

    Cadmium sulfide crystals were shocked along the crystal c axis to peak stresses ranging between 18 and 75 kbar. Stress-time profiles were measured both at the impact surface and after transmission through 1 to 2-mm-thick samples. Detailed analysis of the present data in combination with published static results makes a persuasive case for the completion of the wurtzite to rocksalt phase change in less than 0.2 μs under shock loading. The main findings are: the transition stress is measured to be 32.5±1kbar; transformation to the final state is a two step process with the first step being too rapid (less than 10 ns) to be observed in our experiments and the second step occurring in 0.1 to 0.2 μs; the transition occurs directly from the elastic state prior to any plastic deformation. The calculated mean stress for the transition is 22.9 kbar in good agreement with the 23 kbar pressure reported in static high pressure studies; the presence of large shear stress has no effect on the transition pressure. Our results suggest that the onset of the phase transition results in plastic deformation and, subsequently, the phase transition and plasticity are coupled under shock loading. copyright 1997 American Institute of Physics

  5. Simulations of viscoelastic fluids using a coupled lattice Boltzmann method: Transition states of elastic instabilities

    Directory of Open Access Journals (Sweden)

    Jin Su

    2017-11-01

    Full Text Available Elastic instabilities could happen in viscoelastic flows as the Weissenberg number is enlarged, and this phenomenon makes the numerical simulation of viscoelastic fluids more difficult. In this study, we introduce a coupled lattice Boltzmann method to solve the equations of viscoelastic fluids, which has a great capability of simulating the high Weissenberg number problem. Different from some traditional methods, two kinds of distribution functions are defined respectively for the evolution of the momentum and stress tensor equations. We mainly aim to investigate some key factors of the symmetry-breaking transition induced by elastic instability of viscoelastic fluids using this numerical coupled lattice Boltzmann method. In the results, we firstly find that the ratio of kinematical viscosity has an important influence on the transition of the elastic instability; the transition between the single stationary and cycling dominant vortex can be controlled via changing the ratio of kinematical viscosity in a periodic extensional flow. Finally, we can also observe a new transition state of instability for the flow showing the banded structure at higher Weissenberg number.

  6. Two-body tunnel transitions in a Mn 4 single-molecule magnet

    Science.gov (United States)

    Wernsdorfer, W.; Bhaduri, S.; Tiron, R.; Hendrickson, D. N.; Christou, G.

    2004-05-01

    The one-body tunnel picture of single-molecule magnets (SMMs) is not always sufficient to explain the measured tunnel transitions. An improvement to the picture is proposed by including also two-body tunnel transitions such as spin-spin cross-relaxation (SSCR) which are mediated by dipolar and weak superexchange interactions between molecules. A Mn 4 SMM is used as a model system. At certain external fields, SSCRs lead to additional quantum resonances which show up in hysteresis loop measurements as well-defined steps.

  7. An important rule for realizing metal → half-metal → semiconductor transition in single-molecule junctions

    International Nuclear Information System (INIS)

    Zeng, Jing; Chen, Ke-Qiu; Long, Mengqiu

    2017-01-01

    Recently, Zhong et al (2015 Nano Lett . 15 8091) found that two additional hydrogen atoms can be adsorbed to the opposite aza-bridging nitrogen atoms of the manganese phthalocyanine (MnPc) macrocycle when exposed to H 2 . Thus the symmetry of the MnPc molecule is changed from 4-fold to 2-fold. Motivated by this recent experiment, we theoretically investigate a MnPc-based single-molecule junction in this work and propose a simple and reliable way to realize the transition of its electronic properties. On the basis of spin-polarized density-functional theory calculations combined with the Keldysh nonequilibrium Green’s technique, we find that the gradual hydrogenation in MnPc molecules gives rise to the changes of the hardness of the electron density and spin-selective orbital decoupling, which eventually leads to the realization of the first ever metal  →  half-metal  →  semiconductor transition behavior in single-molecule junctions. Analysis of molecular projected self-consistent Hamiltonian, Mulliken population, and local density of states also reveals an important rule for realizing this transition behavior. Our research confirms that the hydrogenation of MnPc molecules can realize various molecular functionalities in unitary material background. (paper)

  8. An important rule for realizing metal → half-metal → semiconductor transition in single-molecule junctions

    Science.gov (United States)

    Zeng, Jing; Chen, Ke-Qiu; Long, Mengqiu

    2017-06-01

    Recently, Zhong et al (2015 Nano Lett. 15 8091) found that two additional hydrogen atoms can be adsorbed to the opposite aza-bridging nitrogen atoms of the manganese phthalocyanine (MnPc) macrocycle when exposed to H2. Thus the symmetry of the MnPc molecule is changed from 4-fold to 2-fold. Motivated by this recent experiment, we theoretically investigate a MnPc-based single-molecule junction in this work and propose a simple and reliable way to realize the transition of its electronic properties. On the basis of spin-polarized density-functional theory calculations combined with the Keldysh nonequilibrium Green’s technique, we find that the gradual hydrogenation in MnPc molecules gives rise to the changes of the hardness of the electron density and spin-selective orbital decoupling, which eventually leads to the realization of the first ever metal  →  half-metal  →  semiconductor transition behavior in single-molecule junctions. Analysis of molecular projected self-consistent Hamiltonian, Mulliken population, and local density of states also reveals an important rule for realizing this transition behavior. Our research confirms that the hydrogenation of MnPc molecules can realize various molecular functionalities in unitary material background.

  9. Single-electron states near a current-carrying core

    International Nuclear Information System (INIS)

    Masale, M.

    2004-01-01

    The energy spectrum of an electron confined near a current-carrying core is obtained as a function of the azimuthal applied magnetic field within the effective-mass approximation. The double degeneracy of the non-zero electron's axial wave number (k z ) states is lifted by the current-induced magnetic field while that of the non-zero azimuthal quantum number (m) states is preserved. A further analysis is the evaluations of the oscillator strengths for optical transitions involving the lowest-order pair of the electron's energy subbands within the dipole approximation. The radiation field is taken as that of elliptically polarized light incident along the core axis. In this polarization and within the dipole approximation, the allowed transitions are only those governed by the following specific selection rules. The azimuthal quantum numbers of the initial and final states must differ by unity while the electron's axial wave number is conserved. The azimuthal magnetic field is also found to lift the multiple degeneracies of the k z ≠0 interaction integrals as well as those of the oscillator strengths for optical transitions

  10. Hybrid entanglement concentration assisted with single coherent state

    International Nuclear Information System (INIS)

    Guo Rui; Zhou Lan; Sheng Yu-Bo; Gu Shi-Pu; Wang Xing-Fu

    2016-01-01

    Hybrid entangled state (HES) is a new type of entanglement, which combines the advantages of an entangled polarization state and an entangled coherent state. HES is widely discussed in the applications of quantum communication and computation. In this paper, we propose three entanglement concentration protocols (ECPs) for Bell-type HES, W-type HES, and cluster-type HES, respectively. After performing these ECPs, we can obtain the maximally entangled HES with some success probability. All the ECPs exploit the single coherent state to complete the concentration. These protocols are based on the linear optics, which are feasible in future experiments. (paper)

  11. Coherent manipulation of three-qubit states in a molecular single-ion magnet

    Science.gov (United States)

    Jenkins, M. D.; Duan, Y.; Diosdado, B.; García-Ripoll, J. J.; Gaita-Ariño, A.; Giménez-Saiz, C.; Alonso, P. J.; Coronado, E.; Luis, F.

    2017-02-01

    We study the quantum spin dynamics of nearly isotropic Gd3 + ions entrapped in polyoxometalate molecules and diluted in crystals of a diamagnetic Y3 + derivative. The full energy-level spectrum and the orientations of the magnetic anisotropy axes have been determined by means of continuous-wave electron paramagnetic resonance experiments, using X-band (9-10 GHz) cavities and on-chip superconducting waveguides and 1.5-GHz resonators. The results show that seven allowed transitions between the 2 S +1 spin states can be separately addressed. Spin coherence T2 and spin-lattice relaxation T1 rates have been measured for each of these transitions in properly oriented single crystals. The results suggest that quantum spin coherence is limited by residual dipolar interactions with neighbor electronic spins. Coherent Rabi oscillations have been observed for all transitions. The Rabi frequencies increase with microwave power and agree quantitatively with predictions based on the spin Hamiltonian of the molecular spin. We argue that the spin states of each Gd3 + ion can be mapped onto the states of three addressable qubits (or, alternatively, of a d =8 -level "qudit"), for which the seven allowed transitions form a universal set of operations. Within this scheme, one of the coherent oscillations observed experimentally provides an implementation of a controlled-controlled-NOT (or Toffoli) three-qubit gate.

  12. The Astrophysical Weeds: Rotational Transitions in Excited Vibrational States

    Science.gov (United States)

    Alonso, José L.; Kolesniková, Lucie; Alonso, Elena R.; Mata, Santiago

    2017-06-01

    The number of unidentified lines in the millimeter and submillimeter wave surveys of the interstellar medium has grown rapidly. The major contributions are due to rotational transitions in excited vibrational states of a relatively few molecules that are called the astrophysical weeds. necessary data to deal with spectral lines from astrophysical weeds species can be obtained from detailed laboratory rotational measurements in the microwave and millimeter wave region. A general procedure is being used at Valladolid combining different time and/or frequency domain spectroscopic tools of varying importance for providing the precise set of spectroscopic constants that could be used to search for this species in the ISM. This is illustrated in the present contribution through its application to several significant examples. Fortman, S. M., Medvedev, I. R., Neese, C.F., & De Lucia, F.C. 2010, ApJ,725, 1682 Rotational Spectra in 29 Vibrationally Excited States of Interstellar Aminoacetonitrile, L. Kolesniková, E. R. Alonso, S. Mata, and J. L. Alonso, The Astrophysical Journal Supplement Series 2017, (in press).

  13. Nondestructive fluorescent state detection of single neutral atom qubits.

    Science.gov (United States)

    Gibbons, Michael J; Hamley, Christopher D; Shih, Chung-Yu; Chapman, Michael S

    2011-04-01

    We demonstrate nondestructive (lossless) fluorescent state detection of individual neutral atom qubits trapped in an optical lattice. The hyperfine state of the atom is measured with a 95% accuracy and an atom loss rate of 1%. Individual atoms are initialized and detected over 100 times before being lost from the trap, representing a 100-fold improvement in data collection rates over previous experiments. Microwave Rabi oscillations are observed with repeated measurements of one and the same single atom. © 2011 American Physical Society

  14. Single-Phase Microgrid with Seamless Transition Capabilities between Modes of Operation

    DEFF Research Database (Denmark)

    Micallef, Alexander; Apap, Maurice; Spiteri-Staines, Cyril

    2015-01-01

    Microgrids are an effective way to increase the penetration of DG into the grid. They are capable of operating either in grid-connected or in islanded mode thereby increasing the supply reliability for the end user. This paper focuses on achieving seamless transitions from islanded to grid......-connected and vice versa for a single phase microgrid made up from voltage controlled voltage source inverters (VC-VSIs) and current controlled voltage source inverters (CC-VSIs) working together in both modes of operation. The primary control structures for the VC-VSIs and CC-VSIs is considered together...... with the secondary control loops that are used to synchronize the microgrid as a single unit to the grid. Simulation results are given that show the seamless transitions between the two modes without any disconnection times for the CC-VSIs and VC-VSIs connected to the microgrid....

  15. Studies of transition states and radicals by negative ion photodetachment

    Energy Technology Data Exchange (ETDEWEB)

    Metz, Ricardo Baer [Univ. of California, Berkeley, CA (United States)

    1991-12-01

    Negative ion photodetachment is a versatile tool for the production and study of transient neutral species such as reaction intermediates and free radicals. Photodetachment of the stable XHY- anion provides a direct spectroscopic probe of the transition state region of the potential energy surface for the neutral hydrogen transfer reaction X + HY → XH + Y, where X and Y are halogen atoms. The technique is especially sensitive to resonances, which occur at a specific energy, but the spectra also show features due to direct scattering. We have used collinear adiabatic simulations of the photoelectron spectra to evaluate trail potential energy surfaces for the biomolecular reactions and have extended the adiabatic approach to three dimensions and used it to evaluate empirical potential energy surfaces for the I + Hl and Br + HI reactions. In addition, we have derived an empirical, collinear potential energy surface for the Br + HBr reaction that reproduces our experimental results and have extended this surface to three dimensions. Photodetachment of a negative ion can be also used to study neutral free radicals. We have studied the vibrational and electronic spectroscopy of CH2NO2 by photoelectron spectroscopy of CH2NO2-, determining the electron affinity of CH2NO2, gaining insight on the bonding of the 2B1 ground state and observing the 2A2 excited state for the first time. Negative ion photodetachment also provides a novel and versatile source of mass-selected, jet-cooled free radicals. We have studied the photodissociation of CH2NO2 at 270, 235, and 208 nm, obtaining information on the dissociation products by measuring the kinetic energy release in the photodissociation.

  16. Studies of transition states and radicals by negative ion photodetachment

    Energy Technology Data Exchange (ETDEWEB)

    Metz, R.B.

    1991-12-01

    Negative ion photodetachment is a versatile tool for the production and study of transient neutral species such as reaction intermediates and free radicals. Photodetachment of the stable XHY{sup {minus}} anion provides a direct spectroscopic probe of the transition state region of the potential energy surface for the neutral hydrogen transfer reaction X + HY {yields} XH + Y, where X and Y are halogen atoms. The technique is especially sensitive to resonances, which occur at a specific energy, but the spectra also show features due to direct scattering. We have used collinear adiabatic simulations of the photoelectron spectra to evaluate trail potential energy surfaces for the biomolecular reactions and have extended the adiabatic approach to three dimensions and used it to evaluate empirical potential energy surfaces for the I + Hl and Br + HI reactions. In addition, we have derived an empirical, collinear potential energy surface for the Br + HBr reaction that reproduces our experimental results and have extended this surface to three dimensions. Photodetachment of a negative ion can be also used to study neutral free radicals. We have studied the vibrational and electronic spectroscopy of CH{sub 2}NO{sub 2} by photoelectron spectroscopy of CH{sub 2}NO{sub 2}{sup {minus}}, determining the electron affinity of CH{sub 2}NO{sub 2}, gaining insight on the bonding of the {sup 2}B{sub 1} ground state and observing the {sup 2}A{sub 2} excited state for the first time. Negative ion photodetachment also provides a novel and versatile source of mass-selected, jet-cooled free radicals. We have studied the photodissociation of CH{sub 2}NO{sub 2} at 270, 235, and 208 nm, obtaining information on the dissociation products by measuring the kinetic energy release in the photodissociation.

  17. Account of states with indefinite spin in calculations of intercombination collisional transitions

    International Nuclear Information System (INIS)

    Gordeev, S.V.; Chirtsov, A.S.

    1986-01-01

    States with indefinite spin are used in the second order of the perturbation theory as intermediate states for calculating electronic collisional transitions with changing spin between excited states of atoms. The rate coefficient for 4 1 P-4 3 D transition in helium is estimated

  18. Malaysia's 2008 general election – transition from single-party dominance?

    OpenAIRE

    Case, William

    2010-01-01

    Leading theories of transitions from single-party dominant systems begin with economic crisis, the party’s loss of patronage resources, and elite-level defections. The multiparty elections that are then held exert no independent effect, but instead register neutrally the party’s decline and the democratization of politics. This paper, however, shifts attention from the dominant party to citizens and elections in non-crisis conditions. It argues that on key dimensions citizens assess the domin...

  19. Doping-controlled phase transitions in single-layer MoS2

    Science.gov (United States)

    Zhuang, Houlong L.; Johannes, Michelle D.; Singh, Arunima K.; Hennig, Richard G.

    2017-10-01

    The electronic properties of single-layer MoS2 make it an ideal two-dimensional (2D) material for application in electronic devices. Experiments show that MoS2 can undergo structural phase transitions. Applications of single-layer MoS2 will require firm laboratory control over the phase formation. Here we compare the stability and electronic structure of the three experimentally observed single-layer MoS2 phases, 2 H ,1 T , and 1 T' , and an in-plane metal/semiconductor heterostructure. We reveal by density-functional theory calculations that charge doping can induce the phase transition of single-layer MoS2 from the 2 H to the 1 T structure. Further, the 1 T structure undergoes a second phase transition due to the occurrence of a charge-density wave (CDW). By comparing the energies of several possible resulting CDW structures, we find that the 1 T' orthorhombic structure is the most stable one, consistent with experimental observations and previous theoretical studies. We show that the underlying CDW transition mechanism is not due to Fermi surface nesting, but nonetheless, can be controlled by charge doping. In addition, the stability landscape is highly sensitive to charge doping, which can be used as a practical phase selector. We also provide a prescription for obtaining the 1 T' structure via growth or deposition of MoS2 on a Hf substrate, which transfers electrons uniformly and with minimal structural distortion. Finally, we show that lateral heterostructures formed by the 2 H and 1 T' structures exhibit a low interfacial energy of 0.17 eV/Å, a small Schottky barrier of 0.3 eV for holes, and a large barrier of 1.6 eV for electrons.

  20. Detecting critical state before phase transition of complex biological systems by hidden Markov model.

    Science.gov (United States)

    Chen, Pei; Liu, Rui; Li, Yongjun; Chen, Luonan

    2016-07-15

    Identifying the critical state or pre-transition state just before the occurrence of a phase transition is a challenging task, because the state of the system may show little apparent change before this critical transition during the gradual parameter variations. Such dynamics of phase transition is generally composed of three stages, i.e. before-transition state, pre-transition state and after-transition state, which can be considered as three different Markov processes. By exploring the rich dynamical information provided by high-throughput data, we present a novel computational method, i.e. hidden Markov model (HMM) based approach, to detect the switching point of the two Markov processes from the before-transition state (a stationary Markov process) to the pre-transition state (a time-varying Markov process), thereby identifying the pre-transition state or early-warning signals of the phase transition. To validate the effectiveness, we apply this method to detect the signals of the imminent phase transitions of complex systems based on the simulated datasets, and further identify the pre-transition states as well as their critical modules for three real datasets, i.e. the acute lung injury triggered by phosgene inhalation, MCF-7 human breast cancer caused by heregulin and HCV-induced dysplasia and hepatocellular carcinoma. Both functional and pathway enrichment analyses validate the computational results. The source code and some supporting files are available at https://github.com/rabbitpei/HMM_based-method lnchen@sibs.ac.cn or liyj@scut.edu.cn Supplementary data are available at Bioinformatics online. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  1. the steady-state performance characteristics of single phase transfer

    African Journals Online (AJOL)

    2012-11-03

    Nov 3, 2012 ... The paper reports the derivation of the steady- state equivalent circuit of a single phase transfer ... series opposition between the two halves of the ma- ..... from its equivalent circuit of fig 6 for different values of slip. Impedance due to forward field. Zf = Rf + jXf = Rr. 2(2s - 1). + jxr. 2. (19) in parallel with jxm. 2.

  2. Experimental and theoretical studies of vibrational density of states in Fe3O4 single-crystalline thin films

    NARCIS (Netherlands)

    Handke, B; Kozlowski, A; Parlinski, K; Przewoznik, J; Slezak, T; Chumakov, AI; Niesen, L; Kakol, Z; Korecki, J

    This paper presents experimental and theoretical studies of lattice vibrations in a single-crystalline Fe3O4(001) thin film. The investigations were carried out in order to see how the lattice dynamics changes at the Verwey transition. Vibrational densities of states (DOS) were obtained from nuclear

  3. Discovering Unique, Low-Energy Transition States Using Evolutionary Molecular Memetic Computing

    DEFF Research Database (Denmark)

    Ellabaan, Mostafa M Hashim; Ong, Y.S.; Handoko, S.D.

    2013-01-01

    be accurately identified through the transition states. Transition states describe the paths of molecular systems in transiting across stable states. In this article, we present the discovery of unique, low-energy transition states and showcase the efficacy of their identification using the memetic computing...... for the global search, Berny algorithm for individual learning, and make use of the valley-adaptive clearing scheme as the niching strategy in the spirit of Lamarckian learning. Experiments with a number of small non-cyclic molecules demonstrated excellent efficacy of the MMC compared to recent advances...

  4. Magnetization distribution of single-particle states and 2/sup +/ rotational states from muonic atoms

    CERN Document Server

    Backe, H; Engfer, R; Kankeleit, E; Link, R; Michaelsen, R; Petitjean, C; Schellenberg, L; Schneuwly, H; Schröder, W U; Vuilleumier, J L; Walter, H K; Zehnder, A

    1973-01-01

    The lowest states in muonic atoms are rather sensitive to the spatial distribution of the nuclear magnetization density, and several results were deduced from the broadening of the muonic 2p/sub 1/2/-1s/sub 1/2/ and 3d/sub 3/2/-2p/sub 1/2/ transitions. By measuring low energetic transitions such as the 2s/sub 1/2/-2p/sub 1/2/ transition or nuclear gamma -transitions, it is possible to resolve the magnetic hyperfine splittings. The magnetic hf splitting of the 2s/sub 1/2/-2p/sub 1/2/ transition in mu /sup 115/In and of the 3/2/sup +/-1/2/sup +/ nuclear gamma -transitions in mu /sup 203/Tl at 279 keV, and in mu /sup 205/Tl at 204 keV, have been resolved. For the 2/sup +/-0/sup +/ nuclear gamma -transition in mu /sup 190,192/Os at 187 keV and 206 keV, respectively, the magnetic hf splitting of the 2/sup +/ rotational levels and the intensities of the hf components were determined from a nearly resolved doublet splitting. (7 refs).

  5. Using swarm intelligence for finding transition states and reaction paths.

    Science.gov (United States)

    Fournier, René; Bulusu, Satya; Chen, Stephen; Tung, Jamie

    2011-09-14

    We describe an algorithm that explores potential energy surfaces (PES) and finds approximate reaction paths and transition states. A few (≈6) evolving atomic configurations ("climbers") start near a local minimum M1 of the PES. The climbers seek a shallow ascent, low energy, path toward a saddle point S12, cross over to another valley of the PES, and climb down to a new minimum M2 that was not known beforehand. Climbers use both energy and energy derivatives to make individual decisions, and they use relative fitness to make team-based decisions. In sufficiently long runs, they keep exploring and may go through a sequence M1-S12-M2-S23-M3 ... of minima and saddle points without revisiting any of the critical points. We report results on eight small test systems that highlight advantages and disadvantages of the method. We also investigated the PES of Li(8), Al(7)(+), Ag(7), and Ag(2)NH(3) to illustrate potential applications of this new method. © 2011 American Institute of Physics

  6. Fourth-Order Vibrational Transition State Theory and Chemical Kinetics

    Science.gov (United States)

    Stanton, John F.; Matthews, Devin A.; Gong, Justin Z.

    2015-06-01

    Second-order vibrational perturbation theory (VPT2) is an enormously successful and well-established theory for treating anharmonic effects on the vibrational levels of semi-rigid molecules. Partially as a consequence of the fact that the theory is exact for the Morse potential (which provides an appropriate qualitative model for stretching anharmonicity), VPT2 calculations for such systems with appropriate ab initio potential functions tend to give fundamental and overtone levels that fall within a handful of wavenumbers of experimentally measured positions. As a consequence, the next non-vanishing level of perturbation theory -- VPT4 -- offers only slight improvements over VPT2 and is not practical for most calculations since it requires information about force constants up through sextic. However, VPT4 (as well as VPT2) can be used for other applications such as the next vibrational correction to rotational constants (the ``gammas'') and other spectroscopic parameters. In addition, the marriage of VPT with the semi-classical transition state theory of Miller (SCTST) has recently proven to be a powerful and accurate treatment for chemical kinetics. In this talk, VPT4-based SCTST tunneling probabilities and cumulative reaction probabilities are give for the first time for selected low-dimensional model systems. The prospects for VPT4, both practical and intrinsic, will also be discussed.

  7. Ferroelectric InMnO{sub 3}: Growth of single crystals, structure and high-temperature phase transitions

    Energy Technology Data Exchange (ETDEWEB)

    Bekheet, Maged F., E-mail: maged.bekheet@ceramics.tu-berlin.de [Fachbereich Material‐ und Geowissenschaften, Technische Universität Darmstadt, Alarich-Weiss-Straße 2, 64287 Darmstadt (Germany); Fachgebiet Keramische Werkstoffe / Chair of Advanced Ceramic Materials, Institut für Werkstoffwissenschaften und -technologien, Technische Universität Berlin, Hardenbergstraße 40, 10623 Berlin (Germany); Svoboda, Ingrid; Liu, Na [Fachbereich Material‐ und Geowissenschaften, Technische Universität Darmstadt, Alarich-Weiss-Straße 2, 64287 Darmstadt (Germany); Bayarjargal, Lkhamsuren [Institut für Geowissenschaften, Goethe-Universität, Altenhöferallee 1, d-60438 Frankfurt a.M. (Germany); Irran, Elisabeth [Institut für Chemie, Technische Universität Berlin, Straße des 17, Juni 135, 10623 Berlin (Germany); Dietz, Christian; Stark, Robert W.; Riedel, Ralf [Fachbereich Material‐ und Geowissenschaften, Technische Universität Darmstadt, Alarich-Weiss-Straße 2, 64287 Darmstadt (Germany); Gurlo, Aleksander [Fachgebiet Keramische Werkstoffe / Chair of Advanced Ceramic Materials, Institut für Werkstoffwissenschaften und -technologien, Technische Universität Berlin, Hardenbergstraße 40, 10623 Berlin (Germany)

    2016-09-15

    To understand the origin of the ferroelectricity in InMnO{sub 3}, single crystals with average size of 1 mm were grown in PbF{sub 2} flux at 950 °C. The results of single crystal X-ray diffraction, second harmonic generation and piezoresponse force microscopy studies of high-quality InMnO{sub 3} single crystals reveal that the room-temperature state in this material is ferroelectric with P6{sub 3}cm symmetry. The polar InMnO{sub 3} specimen undergoes a reversible phase transition from non-centrosymmetric P6{sub 3}cm structure to a centrosymmetric P6{sub 3}/mmc structure at 700 °C as confirmed by the in situ high-temperature Raman spectroscopic and synchrotron X-ray diffraction experiments. - Graphical abstract: Piezoresponse fore microscopy (PFM) studies of high quality InMnO{sub 3} single crystal revealed that the room-temperature state of this material is ferroelectric with a clear cloverleaf pattern corresponding to six antiphase ferroelectric domains with alternating polarization ±P{sub z}. Display Omitted - Highlights: • InMnO{sub 3} single crystals with average size of 1 mm were grown in PbF{sub 2} flux at 950 °C. • The room-temperature state of InMnO{sub 3} is ferroelectric with polar P6{sub 3}cm structure. • PolarInMnO{sub 3} reversibly transforms to a centrosymmetric P6{sub 3}/mmc structure above 700 °C.

  8. Planar heterostructures of single-layer transition metal dichalcogenides: Composite structures, Schottky junctions, tunneling barriers, and half metals

    Science.gov (United States)

    Aras, Mehmet; Kılıç, ćetin; Ciraci, S.

    2017-02-01

    Planar composite structures formed from the stripes of transition metal dichalcogenides joined commensurately along their zigzag or armchair edges can attain different states in a two-dimensional (2D), single-layer, such as a half metal, 2D or one-dimensional (1D) nonmagnetic metal and semiconductor. Widening of stripes induces metal-insulator transition through the confinements of electronic states to adjacent stripes, that results in the metal-semiconductor junction with a well-defined band lineup. Linear bending of the band edges of the semiconductor to form a Schottky barrier at the boundary between the metal and semiconductor is revealed. Unexpectedly, strictly 1D metallic states develop in a 2D system along the boundaries between stripes, which pins the Fermi level. Through the δ doping of a narrow metallic stripe one attains a nanowire in the 2D semiconducting sheet or narrow band semiconductor. A diverse combination of constituent stripes in either periodically repeating or finite-size heterostructures can acquire critical fundamental features and offer device capacities, such as Schottky junctions, nanocapacitors, resonant tunneling double barriers, and spin valves. These predictions are obtained from first-principles calculations performed in the framework of density functional theory.

  9. A conserved behavioral state barrier impedes transitions between anesthetic-induced unconsciousness and wakefulness: evidence for neural inertia.

    Science.gov (United States)

    Friedman, Eliot B; Sun, Yi; Moore, Jason T; Hung, Hsiao-Tung; Meng, Qing Cheng; Perera, Priyan; Joiner, William J; Thomas, Steven A; Eckenhoff, Roderic G; Sehgal, Amita; Kelz, Max B

    2010-07-30

    One major unanswered question in neuroscience is how the brain transitions between conscious and unconscious states. General anesthetics offer a controllable means to study these transitions. Induction of anesthesia is commonly attributed to drug-induced global modulation of neuronal function, while emergence from anesthesia has been thought to occur passively, paralleling elimination of the anesthetic from its sites in the central nervous system (CNS). If this were true, then CNS anesthetic concentrations on induction and emergence would be indistinguishable. By generating anesthetic dose-response data in both insects and mammals, we demonstrate that the forward and reverse paths through which anesthetic-induced unconsciousness arises and dissipates are not identical. Instead they exhibit hysteresis that is not fully explained by pharmacokinetics as previously thought. Single gene mutations that affect sleep-wake states are shown to collapse or widen anesthetic hysteresis without obvious confounding effects on volatile anesthetic uptake, distribution, or metabolism. We propose a fundamental and biologically conserved concept of neural inertia, a tendency of the CNS to resist behavioral state transitions between conscious and unconscious states. We demonstrate that such a barrier separates wakeful and anesthetized states for multiple anesthetics in both flies and mice, and argue that it contributes to the hysteresis observed when the brain transitions between conscious and unconscious states.

  10. A conserved behavioral state barrier impedes transitions between anesthetic-induced unconsciousness and wakefulness: evidence for neural inertia.

    Directory of Open Access Journals (Sweden)

    Eliot B Friedman

    2010-07-01

    Full Text Available One major unanswered question in neuroscience is how the brain transitions between conscious and unconscious states. General anesthetics offer a controllable means to study these transitions. Induction of anesthesia is commonly attributed to drug-induced global modulation of neuronal function, while emergence from anesthesia has been thought to occur passively, paralleling elimination of the anesthetic from its sites in the central nervous system (CNS. If this were true, then CNS anesthetic concentrations on induction and emergence would be indistinguishable. By generating anesthetic dose-response data in both insects and mammals, we demonstrate that the forward and reverse paths through which anesthetic-induced unconsciousness arises and dissipates are not identical. Instead they exhibit hysteresis that is not fully explained by pharmacokinetics as previously thought. Single gene mutations that affect sleep-wake states are shown to collapse or widen anesthetic hysteresis without obvious confounding effects on volatile anesthetic uptake, distribution, or metabolism. We propose a fundamental and biologically conserved concept of neural inertia, a tendency of the CNS to resist behavioral state transitions between conscious and unconscious states. We demonstrate that such a barrier separates wakeful and anesthetized states for multiple anesthetics in both flies and mice, and argue that it contributes to the hysteresis observed when the brain transitions between conscious and unconscious states.

  11. Youth and administrator perspectives on transition in Kentucky's state agency schools.

    Science.gov (United States)

    Marshall, Amy; Powell, Norman; Pierce, Doris; Nolan, Ronnie; Fehringer, Elaine

    2012-01-01

    Students, a large percentage with disabilities, are at high risk for poor post-secondary outcomes in state agency education programs. This mixed-methods study describes the understandings of student transitions in state agency education programs from the perspectives of youth and administrators. Results indicated that: transition is more narrowly defined within alternative education programs; key strengths of transition practice are present in nontraditional schools; and the coordination barriers within this fluid inter-agency transition system are most apparent in students' frequent inter-setting transitions between nontraditional and home schools.

  12. Photoelectron spectroscopy studies of mixed-valence states of Sm overlayers on transition-metal surfaces

    International Nuclear Information System (INIS)

    Tao Lian.

    1990-01-01

    To investigate and understand how the mixed-valent state of rare earths (RE) is formed and affected by their interactions with transition metals (TM), synchrotron-radiation-excited photoelectron spectroscopy was used to systematically study valence states of Sm overlayers on three TM surfaces as functions of Sm coverages. On polycrystalline Ta, Sm always has a mixed-valent state, consisting of the trivalent state and the divalent state. At a coverage of 0.02 monolayer, Sm has an average valence of 2.24. As the coverage increases, the Sm 3+ and Sm 2+ components increase at different rates. Sm on polycrystalline Cu behaves quite differently. At coverages below one monolayer, all the Sm ions adopt the trivalent state. When the coverage exceeds one monolayer, Sm 2+ ions appear, with a resulting average valence of 2.52. After that the average valence does not change significantly. On a Cu(110) single crystal surface, the situation is found to closely resemble that observed on polycrystalline Cu. These results indicate that the Sm-Ta interaction is weak compared to the Sm-Sm interaction, while the Sm-Cu interaction is stronger and affects the electronic structure

  13. SDF1-CXCR4 Signaling Contributes to the Transition from Acute to Chronic Pain State.

    Science.gov (United States)

    Yang, Fei; Sun, Wei; Luo, Wen-Jun; Yang, Yan; Yang, Fan; Wang, Xiao-Liang; Chen, Jun

    2017-05-01

    Emerging evidence has demonstrated the involvement of stromal cell-derived factor 1 (SDF1, also known as CXCL12)-CXCR4 signaling in a variety of pain state. However, the underlying mechanisms of SDF1-CXCR4 signaling leading to the maintenance of chronic pain states are poorly understood. In the present study, we sought to explore the role of SDF1-CXCR4 signaling in the forming of neuroplasticity by applying a model of the transition from acute to chronic pain state, named as hyperalgesic priming. Utilizing intraplantar bee venom (BV) injection, we successfully established hyperalgesic priming state and found that peripheral treating with AMD3100, a CXCR4 antagonist, or knocking down CXCR4 by intraganglionar CXCR4 small interfering RNA (siRNA) injection could prevent BV-induced primary mechanical hyperalgesia and hyperalgesic priming. Moreover, we showed that single intraplantar active SDF1 protein injection is sufficient to induce acute mechanical hyperalgesia and hyperalgesic priming through CXC4. Intraplantar coinjection of ERK inhibitor, U0126, and PI3K inhibitor, LY294002, as well as two protein translation inhibitors, temsirolimus and cordycepin, prevented the development of SDF1-induced acute mechanical hyperalgesia and hyperalgesic priming. Finally, on the models of complete Freund's adjuvant (CFA)-induced chronic inflammatory pain and spared nerve injury (SNI)-induced chronic neuropathic pain, we observed that knock-down of CXCR4 could both prevent the development and reverse the maintenance of chronic pain state. In conclusion, our present data suggested that through regulating ERK and PI3K-AKT pathways-mediated protein translation SDF1-CXCR4 signaling mediates the transition from acute pain to chronic pain state and finally contributes to the development and maintenance of chronic pain.

  14. A hyperactive transcriptional state marks genome reactivation at the mitosis–G1 transition

    Science.gov (United States)

    Hsiung, Chris C.-S.; Bartman, Caroline R.; Huang, Peng; Ginart, Paul; Stonestrom, Aaron J.; Keller, Cheryl A.; Face, Carolyne; Jahn, Kristen S.; Evans, Perry; Sankaranarayanan, Laavanya; Giardine, Belinda; Hardison, Ross C.; Raj, Arjun; Blobel, Gerd A.

    2016-01-01

    During mitosis, RNA polymerase II (Pol II) and many transcription factors dissociate from chromatin, and transcription ceases globally. Transcription is known to restart in bulk by telophase, but whether de novo transcription at the mitosis–G1 transition is in any way distinct from later in interphase remains unknown. We tracked Pol II occupancy genome-wide in mammalian cells progressing from mitosis through late G1. Unexpectedly, during the earliest rounds of transcription at the mitosis–G1 transition, ∼50% of active genes and distal enhancers exhibit a spike in transcription, exceeding levels observed later in G1 phase. Enhancer–promoter chromatin contacts are depleted during mitosis and restored rapidly upon G1 entry but do not spike. Of the chromatin-associated features examined, histone H3 Lys27 acetylation levels at individual loci in mitosis best predict the mitosis–G1 transcriptional spike. Single-molecule RNA imaging supports that the mitosis–G1 transcriptional spike can constitute the maximum transcriptional activity per DNA copy throughout the cell division cycle. The transcriptional spike occurs heterogeneously and propagates to cell-to-cell differences in mature mRNA expression. Our results raise the possibility that passage through the mitosis–G1 transition might predispose cells to diverge in gene expression states. PMID:27340175

  15. A hyperactive transcriptional state marks genome reactivation at the mitosis-G1 transition.

    Science.gov (United States)

    Hsiung, Chris C-S; Bartman, Caroline R; Huang, Peng; Ginart, Paul; Stonestrom, Aaron J; Keller, Cheryl A; Face, Carolyne; Jahn, Kristen S; Evans, Perry; Sankaranarayanan, Laavanya; Giardine, Belinda; Hardison, Ross C; Raj, Arjun; Blobel, Gerd A

    2016-06-15

    During mitosis, RNA polymerase II (Pol II) and many transcription factors dissociate from chromatin, and transcription ceases globally. Transcription is known to restart in bulk by telophase, but whether de novo transcription at the mitosis-G1 transition is in any way distinct from later in interphase remains unknown. We tracked Pol II occupancy genome-wide in mammalian cells progressing from mitosis through late G1. Unexpectedly, during the earliest rounds of transcription at the mitosis-G1 transition, ∼50% of active genes and distal enhancers exhibit a spike in transcription, exceeding levels observed later in G1 phase. Enhancer-promoter chromatin contacts are depleted during mitosis and restored rapidly upon G1 entry but do not spike. Of the chromatin-associated features examined, histone H3 Lys27 acetylation levels at individual loci in mitosis best predict the mitosis-G1 transcriptional spike. Single-molecule RNA imaging supports that the mitosis-G1 transcriptional spike can constitute the maximum transcriptional activity per DNA copy throughout the cell division cycle. The transcriptional spike occurs heterogeneously and propagates to cell-to-cell differences in mature mRNA expression. Our results raise the possibility that passage through the mitosis-G1 transition might predispose cells to diverge in gene expression states. © 2016 Hsiung et al.; Published by Cold Spring Harbor Laboratory Press.

  16. Shape transition of unstrained flattest single-walled carbon nanotubes under pressure

    Energy Technology Data Exchange (ETDEWEB)

    Mu, Weihua, E-mail: whmu@mit.edu, E-mail: muwh@itp.ac.cn [Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, The Chinese Academy of Sciences, P. O. Box 2735 Beijing 100190 (China); Kavli Institute for Theoretical Physics China, The Chinese Academy of Sciences, P. O. Box 2735 Beijing 100190 (China); Cao, Jianshu, E-mail: jianshu@mit.edu [Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Singapore-MIT Alliance for Research and Technology (SMART), Singapore 138602 (Singapore); Ou-Yang, Zhong-can [State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, The Chinese Academy of Sciences, P. O. Box 2735 Beijing 100190 (China); Kavli Institute for Theoretical Physics China, The Chinese Academy of Sciences, P. O. Box 2735 Beijing 100190 (China); Singapore-MIT Alliance for Research and Technology (SMART), Singapore 138602 (Singapore); Center for Advanced Study, Tsinghua University, Beijing 100084 (China)

    2014-01-28

    Single walled carbon nanotube's (SWCNT's) cross section can be flattened under hydrostatic pressure. One example is the cross section of a single walled carbon nanotube successively deforms from the original round shape to oval shape, then to peanut-like shape. At the transition point of reversible deformation between convex shape and concave shape, the side wall of nanotube is flattest. This flattest tube has many attractive properties. In the present work, an approximate approach is developed to determine the equilibrium shape of this unstrained flattest tube and the curvature distribution of this tube. Our results are in good agreement with recent numerical results, and can be applied to the study of pressure controlled electric properties of single walled carbon nanotubes. The present method can also be used to study other deformed inorganic and organic tube-like structures.

  17. Arab States in Transition | CRDI - Centre de recherches pour le ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Researchers will study key participants in transitions, their motivation, goals and organization; examine the role of institutions in ensuring a successful transition; document the nature of the small revolutions that are accompanying the big ones; and investigate the interplay between ... Date de début. 22 septembre 2011 ...

  18. Discontinuous jamming transitions in soft materials: coexistence of flowing and jammed states

    International Nuclear Information System (INIS)

    Dennin, Michael

    2008-01-01

    Many systems in nature exhibit transitions between fluid-like states and solid-like states, or 'jamming transitions'. There is a strong theoretical foundation for understanding equilibrium phase transitions that involve solidification, or jamming. Other jamming transitions, such as the glass transition, are less well understood. The jamming phase diagram has been proposed to unify the description of equilibrium phase transitions, the glass transitions, and other nonequilibrium jamming transitions. As with equilibrium phase transitions, which can either be first order (discontinuous in a relevant order parameter) or second order (continuous), one would expect that generalized jamming transitions can be continuous or discontinuous. In studies of flow in complex fluids, there is a wide range of evidence for discontinuous transitions, mostly in the context of shear localization, or shear banding. In this paper, I review the experimental evidence for discontinuous transitions. I focus on systems in which there is a discontinuity in the rate of strain between two, coexisting states: one in which the material is flowing and the other in which it is solid-like. (topical review)

  19. Magnetic field-driven 3D-Heisenberg-like phase transition in single crystalline helimagnet FeGe

    Science.gov (United States)

    Xu, Lisha; Fan, Jiyu; Sun, Weifeng; Zhu, Yan; Hu, Dazhi; Liu, Jindong; Ji, Yanda; Shi, Daning; Yang, Hao

    2017-07-01

    Significant microscopic information about fundamental magnetic interactions of magnetic materials is probed via the critical behavior of paramagnetic-ferromagnetic phase transition. In this work, we demonstrate that the critical behavior of cubic single crystalline FeGe belongs to the isotropic 3D-Heisenberg universality class by measuring the field dependence of magnetic entropy change. The above transition is one of the magnetic field-driven phase transitions but has a feature of the crossover from first- to second-order phase transition. A phenomenological model based on the evolution of magnetic skyrmions was proposed to qualitatively understand the phase transition.

  20. Driven spin transitions in fluorinated single- and bilayer-graphene quantum dots

    Science.gov (United States)

    Żebrowski, D. P.; Peeters, F. M.; Szafran, B.

    2017-06-01

    Spin transitions driven by a periodically varying electric potential in dilute fluorinated graphene quantum dots are investigated. Flakes of monolayer graphene as well as electrostatic electron traps induced in bilayer graphene are considered. The stationary states obtained within the tight-binding approach are used as the basis for description of the system dynamics. The dilute fluorination of the top layer lifts the valley degeneracy of the confined states and attenuates the orbital magnetic dipole moments due to current circulation within the flake. The spin-orbit coupling introduced by the surface deformation of the top layer induced by the adatoms allows the spin flips to be driven by the AC electric field. For the bilayer quantum dots the spin flip times is substantially shorter than the spin relaxation. Dynamical effects including many-photon and multilevel transitions are also discussed.

  1. Spin-Forbidden Reactions: Adiabatic Transition States Using Spin-Orbit Coupled Density Functional Theory.

    Science.gov (United States)

    Gaggioli, Carlo Alberto; Belpassi, Leonardo; Tarantelli, Francesco; Harvey, Jeremy N; Belanzoni, Paola

    2017-10-31

    A spin-forbidden chemical reaction involves a change in the total electronic spin state from reactants to products. The mechanistic study is challenging because such a reaction does not occur on a single diabatic potential energy surface (PES), but rather on two (or multiple) spin diabatic PESs. One possible approach is to calculate the so-called "minimum energy crossing point" (MECP) between the diabatic PESs, which however is not a stationary point. Inclusion of spin-orbit coupling between spin states (SOC approach) allows the reaction to occur on a single adiabatic PES, in which a transition state (TS SOC) as well as activation free energy can be calculated. This Concept article summarizes a previously published application in which, for the first time, the SOC effects, using spin-orbit ZORA Hamiltonian within density functional theory (DFT) framework, are included and account for the mechanism of a spin-forbidden reaction in gold chemistry. The merits of the MECP and TS SOC approaches and the accuracy of the results are compared, considering both our recent calculations on molecular oxygen addition to gold(I)-hydride complexes and new calculations for the prototype spin-forbidden N 2 O and N 2 Se dissociation reactions. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Transitions in the computational power of thermal states for measurement-based quantum computation

    International Nuclear Information System (INIS)

    Barrett, Sean D.; Bartlett, Stephen D.; Jennings, David; Doherty, Andrew C.; Rudolph, Terry

    2009-01-01

    We show that the usefulness of the thermal state of a specific spin-lattice model for measurement-based quantum computing exhibits a transition between two distinct 'phases' - one in which every state is a universal resource for quantum computation, and another in which any local measurement sequence can be simulated efficiently on a classical computer. Remarkably, this transition in computational power does not coincide with any phase transition, classical, or quantum in the underlying spin-lattice model.

  3. Investigation of a phase transition in a single optically levitated microdroplet by Raman-Mie scattering.

    Science.gov (United States)

    Trunk, M; Lübben, J F; Popp, J; Schrader, B; Kiefer, W

    1997-05-20

    Light-scattering measurements of optically levitated microdroplets containing three components, glycerin, water, and ammonium sulfate, are presented. Evaporation of the microdroplet is studied by means of morphology-dependent resonances observed in both Raman spectra as well as elastically scattered light and by the simultaneous measurement of the laser power. The phase transition from the liquid to the solid state of ammonium sulfate inside the microdroplet is observed by means of morphology-dependent resonances and Raman scattering.

  4. From single helical relaxed states to helical equilibria

    Science.gov (United States)

    Paccagnella, Roberto

    2018-02-01

    This paper analyzes the relationship between the Single Helical relaxed states studied by R. Paccagnella [Phys. Plasmas 23, 092512 (2016)] and the so-called "helical ohmic equilibria," i.e., plasma states that are solutions of the helical Grad Shafranov equation and that satisfy the constraint imposed by the Ohm law. The existence of marginally stable helical equilibria is clearly demonstrated, while the ohmic constraint is not exactly satisfied within the proposed first order perturbation theory. The model predictions are however satisfactorily compared with experimental trends.

  5. Fast Transition between High-soft and Low-soft States in GRS 1915 ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    intensity in GRS 1758 − 258. Though transition from low-hard to high-soft states are seen in many Galactic black hole candidate sources, a transition between two different intensity states (high and low) with similar physical parameters of the accretion disk was not observed in GRS 1915 + 105 or in any other black hole ...

  6. 31 CFR 560.406 - Transshipment or transit through United States prohibited.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Transshipment or transit through United States prohibited. 560.406 Section 560.406 Money and Finance: Treasury Regulations Relating to... TRANSACTIONS REGULATIONS Interpretations § 560.406 Transshipment or transit through United States prohibited...

  7. Status of Credentialing Structures Related to Secondary Transition: A State-Level Policy Analysis

    Science.gov (United States)

    Simonsen, Monica L.; Novak, Jeanne A.; Mazzotti, Valerie L.

    2018-01-01

    To understand the current status of transition-related credentialing systems in driving personnel preparation, it is necessary to identify which state education and rehabilitation services agencies are currently providing certification and licensure in the area of secondary transition. The purpose of this study was to examine the current state of…

  8. Predicting landscape vegetation dynamics using state-and-transition simulation models

    Science.gov (United States)

    Colin J. Daniel; Leonardo. Frid

    2012-01-01

    This paper outlines how state-and-transition simulation models (STSMs) can be used to project changes in vegetation over time across a landscape. STSMs are stochastic, empirical simulation models that use an adapted Markov chain approach to predict how vegetation will transition between states over time, typically in response to interactions between succession,...

  9. Growth and electronic structure of single-layered transition metal dichalcogenides

    DEFF Research Database (Denmark)

    Dendzik, Maciej

    2016-01-01

    The discovery of graphene has opened a novel research direction focused on the properties of 2D materials. Transition metal dichalcogenides (TMDCs) were quickly identified as important materials due to the great variety of electronic properties that they manifest – properties that are markedly...... different from graphene’s. For example, semiconducting TMDCs undergo an indirectdirect band gap transition when thinned to a single layer (SL); this results in greatly enhanced photoluminescence, making those materials attractive for applications in optoelectronics. Furthermore, metallic TMDCs can host...... TMDCs is directly studied with angle-resolved photoemission spectroscopy (ARPES) and x-ray photoelectron spectroscopy (XPS) techniques. Experimental results are compared with density-functional theory calculations (DFT), both for a free-standing layer and for a layer adsorbed on a metallic substrate...

  10. Migration transition in small Northern and Eastern Caribbean states.

    Science.gov (United States)

    Mcelroy, J L; De Albuquerque, K

    1988-01-01

    1 area of intra-Caribbean migration that has been overlooked is the "migration transition"--the transformation of rapidly modernizing societies from net labor exporters to net labor importers. This article assembles 8 case studies to 1) briefly present a spectrum of migration experiences in the Caribbean, 2) uncover some transitions under way, 3) pinpoint the forces that underlie the migration transition, and 4) point out some of the more important policy implications of labor migration reversals. The 8 island societies sampled for illustration purposes include 1) the Bahamas and the US Virgin Islands as post-migration transition societies (Zelinsky's advanced society), 2) the British Virgin Islands and the Cayman Islands as undergoing transition (Zelinsky's late transitional society), and 3) Anguilla, St. Kitts-Nevis, Turks and Caicos, and Montserrat as premigration transition societies (Zelinsky's early transitional society). Population data for the islands were derived primarily from the West Indian censuses and government statistics. These 8 historical sketches reveal certain commonalities. All are at various stages in a long-term economic restructuring to displace traditional staple crops with more income elastic, high value export services. In such societies, population growth and progress along the migration transition is an increasing function of this kind of successful export substitution. In addition, along the migration and economic transitions, such insular economies exhibit a relatively large public sector (20-30% of all activity), declining unemployment, increasing fiscal autonomy, and are committed to a development strategy remarkably similar to the "successful" model of the Bahamas and the US Virgin Islands. Cursory evidence suggests that, because of intersectoral competition for land and labor, there is an inverse relationship between farm effort/manufacturing employment and tourism intensity. This review suggests that small islands undergoing

  11. Modeling Enzymatic Transition States by Force Field Methods

    DEFF Research Database (Denmark)

    Hansen, Mikkel Bo; Jensen, Hans Jørgen Aagaard; Jensen, Frank

    2009-01-01

    The SEAM method, which models a transition structure as a minimum on the seam of two diabatic surfaces represented by force field functions, has been used to generate 20 transition structures for the decarboxylation of orotidine by the orotidine-5'-monophosphate decarboxylase enzyme. The dependence...... by various electronic structure methods, where part of the enzyme is represented by a force field description and the effects of the solvent are represented by a continuum model. The relative energies vary by several hundreds of kJ/mol between the transition structures, and tests showed that a large part...

  12. Electrochemical reduction of CO2on graphene supported transition metals - towards single atom catalysts.

    Science.gov (United States)

    He, Haiying; Jagvaral, Yesukhei

    2017-05-10

    In this study, we have investigated the use of single metal atoms supported on defective graphene as catalysts for the electrochemical reduction of CO 2 using the first-principles approach and the computational hydrogen electrode model. Reaction pathways to produce a variety of C 1 products CO, HCOOH, HCHO, CH 3 OH and CH 4 have been studied in detail for five representative transition metals Ag, Cu, Pd, Pt, and Co. Different pathways were revealed in contrast to those found for metallic crystalline surfaces and nanoparticles. These single atom catalysts have demonstrated a general improvement in rate limiting potentials to generate C 1 hydrocarbons. They also show distinct differences in terms of their efficiency and selectivity in CO 2 reduction, which can be correlated with their elemental properties as a function of their group number in the periodic table. Six best candidates for CH 4 production are identified by conducting computational screening of 28 d-block transition metals. Ag has the lowest overpotential (0.73 V), and is followed by Zn, Ni, Pd, Pt and Ru with overpotentials all below 1 V. Cu in the supported single atom form shows a strong preference towards producing CH 3 OH with an overpotential of 0.68 V well below the value of 1.04 V for producing CH 4 .

  13. Structural analysis of silanediols as transition-state-analogue inhibitors of the benchmark metalloprotease thermolysin.

    Science.gov (United States)

    Juers, Douglas H; Kim, Jaeseung; Matthews, Brian W; Sieburth, Scott McN

    2005-12-20

    Dialkylsilanediols have been found to be an effective functional group for the design of active-site-directed protease inhibitors, including aspartic (HIV protease) and metallo (ACE and thermolysin) proteases. The use of silanediols is predicated on its resemblance to the hydrated carbonyl transition-state structure of amide hydrolysis. This concept has been tested by replacing the presumed tetrahedral carbon of a thermolysin substrate with a silanediol group, resulting in an inhibitor with an inhibition constant K(i) = 40 nM. The structure of the silanediol bound to the active site of thermolysin was found to have a conformation very similar to that of a corresponding phosphonamidate inhibitor (K(i) = 10 nM). In both cases, a single oxygen is within bonding distance to the active-site zinc ion, mimicking the presumed tetrahedral transition state. There are binding differences that appear to be related to the presence or absence of protons on the oxygens attached to the silicon or phosphorus. This is the first crystal structure of an organosilane bound to the active site of a protease.

  14. Characteristics of the Mott transition and electronic states of high-temperature cuprate superconductors from the perspective of the Hubbard model

    Science.gov (United States)

    Kohno, Masanori

    2018-04-01

    A fundamental issue of the Mott transition is how electrons behaving as single particles carrying spin and charge in a metal change into those exhibiting separated spin and charge excitations (low-energy spin excitation and high-energy charge excitation) in a Mott insulator. This issue has attracted considerable attention particularly in relation to high-temperature cuprate superconductors, which exhibit electronic states near the Mott transition that are difficult to explain in conventional pictures. Here, from a new viewpoint of the Mott transition based on analyses of the Hubbard model, we review anomalous features observed in high-temperature cuprate superconductors near the Mott transition.

  15. Energy Demand Modeling Methodology of Key State Transitions of Turning Processes

    Directory of Open Access Journals (Sweden)

    Shun Jia

    2017-04-01

    Full Text Available Energy demand modeling of machining processes is the foundation of energy optimization. Energy demand of machining state transition is integral to the energy requirements of the machining process. However, research focus on energy modeling of state transition is scarce. To fill this gap, an energy demand modeling methodology of key state transitions of the turning process is proposed. The establishment of an energy demand model of state transition could improve the accuracy of the energy model of the machining process, which also provides an accurate model and reliable data for energy optimization of the machining process. Finally, case studies were conducted on a CK6153i CNC lathe, the results demonstrating that predictive accuracy with the proposed method is generally above 90% for the state transition cases.

  16. Isothermal equation of state of a lithium fluoride single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Kim, K.Y.

    1975-01-01

    An isothermal equation of state of a LiF single crystal was determined from length change measurements of the specimen as a function of hydrostatic pressure up to approximately 7 kbars at 28 to 41/sup 0/C. The length change was measured with an accuracy of approximately 500 A by using a Fabry Perot type He--Ne laser interferometer for a 1-m long specimen at temperatures constant to less than 0.002/sup 0/C. Several two- and three-parameter equations of state were used in analyzing the measured pressure-volume data. The computer fit for each equation of state determines not only the value of its parameters but also the standard deviations associated with them and one dependent variable, either pressure or volume. With the parameters determined, the equations of state are extrapolated to approximately 5 megabars in order to see discrepancies. Using the Born model of ionic solids, two equations of state were derived both from a power law potential and from an exponential form for the repulsive energy of alkali metal halides and used to fit the pressure-volume data of a LiF single crystal. They are also extrapolated to approximately 5 megabars. The Birch's two-parameter equation and the Grover, Getting, and Kennedy equation are indistinguishable from the two equations of state derived from the Born model for pressures approximately equal to or less than 800 kbars within +-20 kbars. The above four equations of state also fit closely the Pagannone and Drickamer static compression data, the Christian shock wave data, and the Kormer et al. shock wave data. The isothermal bulk modulus and its first pressure derivative at atmospheric pressure and 28.83/sup 0/C are 664.5 +- 0.5 kbars and 5.40 +- 0.18, respectively, in close agreement with those values ultrasonically measured by R. A. Miller and C. S. Smith. (auth)

  17. Valley polarization in magnetically doped single-layer transition-metal dichalcogenides

    KAUST Repository

    Cheng, Yingchun

    2014-04-28

    We demonstrate that valley polarization can be induced and controlled in semiconducting single-layer transition-metal dichalcogenides by magnetic doping, which is important for spintronics, valleytronics, and photonics devices. As an example, we investigate Mn-doped MoS2 by first-principles calculations. We study how the valley polarization depends on the strength of the spin orbit coupling and the exchange interaction and discuss how it can be controlled by magnetic doping. Valley polarization by magnetic doping is also expected for other honeycomb materials with strong spin orbit coupling and the absence of inversion symmetry.

  18. Dielectric behavior and phase transition in [111]-oriented PIN–PMN–PT single crystals under dc bias

    Directory of Open Access Journals (Sweden)

    Yuhui Wan

    2014-01-01

    Full Text Available Temperature and electric field dependences of the dielectric behavior and phase transition for [111]-oriented 0.23PIN–0.52PMN–0.25PT (PIN-PMN–0.25PT and 0.24PIN–0.43PMN–0.33PT (PIN–PMN–0.33PT single crystals were investigated over a temperature range from -100°C to 250°C using field-heating (FH dielectric measurements. The transition phenomenon from ferroelectric microdomain to macrodomain was found in rhombohedra (R phase region in the single crystals under dc bias. This transition temperature Tf of micro-to-macrodomain is sensitive to dc bias and move quickly to lower temperature with increasing dc bias. The phase transition temperatures in the two single crystals shift toward high temperature and the dielectric permittivities at the phase transition temperature decrease with increasing dc bias. Especially, the phase transition peaks are gradually broad in PIN–PMN–0.33PT single crystal with the increasing dc bias. Effects of dc bias on the dielectric behavior and phase transition in PIN–PMN–PT single crystals are discussed.

  19. Alpha-decay-induced fracturing in zircon - The transition from the crystalline to the metamict state

    Science.gov (United States)

    Chakoumakos, Bryan C.; Murakami, Takashi; Lumpkin, Gregory R.; Ewing, Rodney C.

    1987-01-01

    Zonation due to alpha-decay damage in a natural single crystal of zircon from Sri Lanka is discussed. The zones vary in thickness on a scale from one to hundreds of microns. The uranium and thorium concentrations vary from zone to zone such that the alpha decay dose is between 0.2 x 10 to the 16th and 0.8 x 10 to the 16th alpha-events per milligram. The transition from the crystalline to the aperiodic metamict state occurs over this dose range. At doses greater than 0.8 x 10 to the 16th alpha events/mg there is no evidence for long-range order. This type of damage will accumulate in actinide-bearing, ceramic nuclear waste forms. The systematic pattern of fractures would occur in crystalline phases that are zoned with respect to actinide radionuclides.

  20. Complex transitions between spike, burst or chaos synchronization states in coupled neurons with coexisting bursting patterns

    International Nuclear Information System (INIS)

    Gu Hua-Guang; Chen Sheng-Gen; Li Yu-Ye

    2015-01-01

    We investigated the synchronization dynamics of a coupled neuronal system composed of two identical Chay model neurons. The Chay model showed coexisting period-1 and period-2 bursting patterns as a parameter and initial values are varied. We simulated multiple periodic and chaotic bursting patterns with non-(NS), burst phase (BS), spike phase (SS), complete (CS), and lag synchronization states. When the coexisting behavior is near period-2 bursting, the transitions of synchronization states of the coupled system follows very complex transitions that begins with transitions between BS and SS, moves to transitions between CS and SS, and to CS. Most initial values lead to the CS state of period-2 bursting while only a few lead to the CS state of period-1 bursting. When the coexisting behavior is near period-1 bursting, the transitions begin with NS, move to transitions between SS and BS, to transitions between SS and CS, and then to CS. Most initial values lead to the CS state of period-1 bursting but a few lead to the CS state of period-2 bursting. The BS was identified as chaos synchronization. The patterns for NS and transitions between BS and SS are insensitive to initial values. The patterns for transitions between CS and SS and the CS state are sensitive to them. The number of spikes per burst of non-CS bursting increases with increasing coupling strength. These results not only reveal the initial value- and parameter-dependent synchronization transitions of coupled systems with coexisting behaviors, but also facilitate interpretation of various bursting patterns and synchronization transitions generated in the nervous system with weak coupling strength. (paper)

  1. Zeroth order phase transition in a holographic superconductor with single impurity

    NARCIS (Netherlands)

    Zeng, Hua Bi; Zhang, Hai-Qing

    We investigate the single normal impurity effect in a superconductor by the holographic method. When the size of impurity is much smaller than the host superconductor, we can reproduce the Anderson theorem, which states that a conventional s-wave superconductor is robust to a normal (non-magnetic)

  2. Organometallic synthesis, reactivity and catalysis in the solid state using well-defined single-site species

    Science.gov (United States)

    Pike, Sebastian D.; Weller, Andrew S.

    2015-01-01

    Acting as a bridge between the heterogeneous and homogeneous realms, the use of discrete, well-defined, solid-state organometallic complexes for synthesis and catalysis is a remarkably undeveloped field. Here, we present a review of this topic, focusing on describing the key transformations that can be observed at a transition-metal centre, as well as the use of well-defined organometallic complexes in the solid state as catalysts. There is a particular focus upon gas–solid reactivity/catalysis and single-crystal-to-single-crystal transformations. PMID:25666064

  3. Spin quantum tunneling via entangled states in a dimer of exchange coupled single-molecule magnets

    Science.gov (United States)

    Tiron, R.; Wernsdorfer, W.; Aliaga-Alcalde, N.; Foguet-Albiol, D.; Christou, G.

    2004-03-01

    A new family of supramolecular, antiferromagnetically exchange-coupled dimers of single-molecule magnets (SMMs) has recently been reported [W. Wernsdorfer, N. Aliaga-Alcalde, D.N. Hendrickson, and G. Christou, Nature 416, 406 (2002)]. Each SMM acts as a bias on its neighbor, shifting the quantum tunneling resonances of the individual SMMs. Hysteresis loop measurements on a single crystal of SMM-dimers have now established quantum tunneling of the magnetization via entangled states of the dimer. This shows that the dimer really does behave as a quantum-mechanically coupled dimer. The transitions are well separated, suggesting long coherence times compared to the time scale of the energy splitting. This result is of great importance if such systems are to be used for quantum computing. It also allows the measurement of the longitudinal and transverse superexchange coupling constants [Phys. Rev. Lett. 91, 227203 (2003)].

  4. Neoliberalism, welfare policy and health: a qualitative meta-synthesis of single parents' experience of the transition from welfare to work.

    Science.gov (United States)

    Cook, Kay

    2012-09-01

    Following the United States' lead, the emergence of neoliberal welfare policy across the western world has resulted in employment programmes for single parents, who are predominantly single mothers. While some governments claim that employment will improve single parents' incomes and well-being, researchers dispute that single parents can unproblematically move into the workforce, with net positive effects. While researchers have quantified the socio-economic effect of these programmes, in particular on participant health, no study has yet synthesized participants' experiences of welfare-to-work. Here, I present a meta-synthesis of eight qualitative health-related studies of single parents' (and exclusively single mothers') welfare-to-work transition. I report that single mothers faced a combination of health and economic issues which made their transition from welfare to work difficult, including degrees of poor physical and mental health. For participants in the United States, these health issues were often compounded by a loss of health benefits on moving into low-wage employment. In countries where a return to employment was required before children reached school age, a lack of affordable and appropriate child care, especially for children with health problems, exacerbated these difficulties. As a result of scarce resources, single mothers in receipt of welfare benefits often relied on food banks or went without food. A return to the workforce did not alleviate this problem as additional child care and reduced government subsidies depleted the funds available for food. I conclude that welfare-to-work policies are underpinned by the neoliberal assumption that the market more efficiently distributes resources than the State. However, for the women in the studies examined here, labour market participation often depleted access to essential resources. Interventions to address the 'problem' of welfare dependency must recognize the complex interplay between work

  5. Quantum State Restoration and Single-Copy Tomography for Ground States of Hamiltonians

    Science.gov (United States)

    Farhi, Edward; Gosset, David; Hassidim, Avinatan; Lutomirski, Andrew; Nagaj, Daniel; Shor, Peter

    2010-11-01

    Given a single copy of an unknown quantum state, the no-cloning theorem limits the amount of information that can be extracted from it. Given a gapped Hamiltonian, in most situations it is impractical to compute properties of its ground state, even though in principle all the information about the ground state is encoded in the Hamiltonian. We show in this Letter that if you know the Hamiltonian of a system and have a single copy of its ground state, you can use a quantum computer to efficiently compute its local properties. Specifically, in this scenario, we give efficient algorithms that copy small subsystems of the state and estimate the full statistics of any local measurement.

  6. Can a quantum state over time resemble a quantum state at a single time?

    Science.gov (United States)

    Horsman, Dominic; Heunen, Chris; Pusey, Matthew F; Barrett, Jonathan; Spekkens, Robert W

    2017-09-01

    The standard formalism of quantum theory treats space and time in fundamentally different ways. In particular, a composite system at a given time is represented by a joint state, but the formalism does not prescribe a joint state for a composite of systems at different times. If there were a way of defining such a joint state, this would potentially permit a more even-handed treatment of space and time, and would strengthen the existing analogy between quantum states and classical probability distributions. Under the assumption that the joint state over time is an operator on the tensor product of single-time Hilbert spaces, we analyse various proposals for such a joint state, including one due to Leifer and Spekkens, one due to Fitzsimons, Jones and Vedral, and another based on discrete Wigner functions. Finding various problems with each, we identify five criteria for a quantum joint state over time to satisfy if it is to play a role similar to the standard joint state for a composite system: that it is a Hermitian operator on the tensor product of the single-time Hilbert spaces; that it represents probabilistic mixing appropriately; that it has the appropriate classical limit; that it has the appropriate single-time marginals; that composing over multiple time steps is associative. We show that no construction satisfies all these requirements. If Hermiticity is dropped, then there is an essentially unique construction that satisfies the remaining four criteria.

  7. State of corruption in transition: case of the Czech Republic

    Czech Academy of Sciences Publication Activity Database

    Lízal, Lubomír; Kočenda, Evžen

    2001-01-01

    Roč. 2, č. 2 (2001), s. 137-160 ISSN 1566-0141 R&D Projects: GA AV ČR KSK9058117 Institutional research plan: CEZ:AV0Z7085904 Keywords : Czech Republic * transition * corruption Subject RIV: AH - Economics

  8. State of the Art of Current Practices for Transit Transfers.

    Science.gov (United States)

    1981-07-01

    The major objectives of the study are to: (1) describe and summarize the transfer policies currently in use on U.S. transit properties; (2) identify reasons why properties use or do not use particular transfer policies; (3) determine the consequences...

  9. Single-Photon Switching and Entanglement of Solid- State Qubits in an Integrated Nanophotonic System

    Science.gov (United States)

    Evans, Ruffin; Sipahigil, Alp; Sukachev, Denis; Burek, Michael; Borregaard, Johannes; Bhaskar, Mihir; Nguyen, Christian; Pacheco, Jose; Bielejec, Edward; Loncar, Marko; Lukin, Mikhail

    2017-04-01

    Efficient interfaces between photons and quantum emitters form the basis for quantum networks and enable optical nonlinearities at the single-photon level. We demonstrate a platform for scalable quantum nanophotonics based on silicon-vacancy (SiV) color centers coupled to diamond nanodevices. By placing SiV centers inside diamond photonic crystal cavities, we realize a quantum-optical switch controlled by a single color center. We control the switch using SiV metastable states and observe switching at the single-photon level. Raman transitions are used to realize a single-photon source with a tunable frequency and bandwidth in a diamond waveguide. By measuring intensity correlations of indistinguishable Raman photons emitted into a single waveguide, we observe quantum interference resulting from the superradiant emission of two entangled SiV centers. We also discuss current work to extend the coherence time of the SiV spin degree of freedom, engineer deterministic multi-emitter interactions via the cavity mode, and related work with the Germanium-Vacancy center.

  10. Chaotic Dynamics Mediate Brain State Transitions, Driven by Changes in Extracellular Ion Concentrations

    DEFF Research Database (Denmark)

    Rasmussen, Rune; Jensen, Mogens H.; Heltberg, Mathias L.

    2017-01-01

    the transition from sleep to wakefulness. We find that sleep is governed by stable, self-sustained oscillations in neuronal firing patterns, whereas the quiet awake state and active awake state are both governed by irregular oscillations and chaotic dynamics; transitions between these separable awake states......Previous studies have suggested that changes in extracellular ion concentrations initiate the transition from an activity state that characterizes sleep in cortical neurons to states that characterize wakeful- ness. However, because neuronal activity and extra- cellular ion concentrations...... are interdependent, isolating their unique roles during sleep-wake transitions is not possible in vivo. Here, we extend the Averaged-Neuron model and demonstrate that, although changes in extracellular ion concentrations occur concurrently, decreasing the conductance of calcium-dependent potassium channels initiates...

  11. UP-DOWN cortical dynamics reflect state transitions in a bistable network.

    Science.gov (United States)

    Jercog, Daniel; Roxin, Alex; Barthó, Peter; Luczak, Artur; Compte, Albert; de la Rocha, Jaime

    2017-08-04

    In the idling brain, neuronal circuits transition between periods of sustained firing (UP state) and quiescence (DOWN state), a pattern the mechanisms of which remain unclear. Here we analyzed spontaneous cortical population activity from anesthetized rats and found that UP and DOWN durations were highly variable and that population rates showed no significant decay during UP periods. We built a network rate model with excitatory (E) and inhibitory (I) populations exhibiting a novel bistable regime between a quiescent and an inhibition-stabilized state of arbitrarily low rate. Fluctuations triggered state transitions, while adaptation in E cells paradoxically caused a marginal decay of E-rate but a marked decay of I-rate in UP periods, a prediction that we validated experimentally. A spiking network implementation further predicted that DOWN-to-UP transitions must be caused by synchronous high-amplitude events. Our findings provide evidence of bistable cortical networks that exhibit non-rhythmic state transitions when the brain rests.

  12. Transition probabilities of health states for workers in Malaysia using a Markov chain model

    Science.gov (United States)

    Samsuddin, Shamshimah; Ismail, Noriszura

    2017-04-01

    The aim of our study is to estimate the transition probabilities of health states for workers in Malaysia who contribute to the Employment Injury Scheme under the Social Security Organization Malaysia using the Markov chain model. Our study uses four states of health (active, temporary disability, permanent disability and death) based on the data collected from the longitudinal studies of workers in Malaysia for 5 years. The transition probabilities vary by health state, age and gender. The results show that men employees are more likely to have higher transition probabilities to any health state compared to women employees. The transition probabilities can be used to predict the future health of workers in terms of a function of current age, gender and health state.

  13. Exploration of the transition state of the alcohol oxidase catalytic reaction using quantum chemistry methods

    OpenAIRE

    Lasavičius, Edvinas

    2016-01-01

    Alcohol oxidases (AO) have a great potential for the use organic synthesis and manufacturing of biosensors. In this study, a transition state of oxidation of alcohol by AO was investigated using computational chemistry methods. First, the transition state and the intrinsic reaction path were de-termined using Hartree-Fock (HF) theory and STO-3G minimal basis set. Further the calculations of the transition states, reactants and products were expanded to include 3-21G and 6-31*G basis sets at t...

  14. Coherent state approach for the Φ6-lattice model and phase transitions

    International Nuclear Information System (INIS)

    Aguero-Granados, M.A.; Makhan'kov, V.G.

    1991-01-01

    Phase transitions in the lattice version of the Φ 6 -field theory are studied. The generalized coherent states approach to is used. In such a way the roles of kinks and bubbles in phase transitions have been reexamined. It is shown via a numerical analysis that first and second order phase transitions appear due to the behaviour of kinks and bubbles excitations. 12 refs.; 10 figs

  15. Hybrid entanglement concentration assisted with single coherent state

    Science.gov (United States)

    Rui, Guo; Lan, Zhou; Shi-Pu, Gu; Xing-Fu, Wang; Yu-Bo, Sheng

    2016-03-01

    Hybrid entangled state (HES) is a new type of entanglement, which combines the advantages of an entangled polarization state and an entangled coherent state. HES is widely discussed in the applications of quantum communication and computation. In this paper, we propose three entanglement concentration protocols (ECPs) for Bell-type HES, W-type HES, and cluster-type HES, respectively. After performing these ECPs, we can obtain the maximally entangled HES with some success probability. All the ECPs exploit the single coherent state to complete the concentration. These protocols are based on the linear optics, which are feasible in future experiments. Project supported by the National Natural Science Foundation of China (Grant Nos. 11474168 and 61401222), the Natural Science Foundation of Jiangsu Province, China (Grant No. BK20151502), the Qing Lan Project in Jiangsu Province, China, the Natural Science Foundation of Jiangsu Higher Education Institutions, China (Grant No. 15KJA120002), and the Priority Academic Development Program of Jiangsu Higher Education Institutions, China.

  16. Shape transition of state density for bosonic systems

    Indian Academy of Sciences (India)

    For a finite boson system, the ensemble-averaged state density has been computed with respect to the body interaction rank . The shape of such a state density changes from Gaussian to semicircle as the body rank of the interaction increases. This state density is expressed as a linear superposition of Gaussian and ...

  17. M1 and E2 transitions in the ground-state configuration of atomic ...

    Indian Academy of Sciences (India)

    state configuration are particularly useful because their relatively long wavelengths make them convenient for spectroscopic studies [1]. Although the atomic kinetics depend on, in particular, optical allowed transitions (E1), the weak forbidden transitions (in particular, magnetic dipole, M1 and electric quadrupole, E2) have ...

  18. Estimation and asymptotic theory for transition probabilities in markov renewal multi-state models

    NARCIS (Netherlands)

    Spitoni, Cristian|info:eu-repo/dai/nl/304625957; Verduijn, Marion; Putter, Hein

    2014-01-01

    In this paper we discuss estimation of transition probabilities for semi-Markov multi-state models. Non-parametric and semi-parametric estimators of the transition probabilities for a large class of models (forward going models) are proposed. Large sample theory is derived using the functional delta

  19. Transition Metal Oxides: Many Body Physics Meets Solid State ...

    Indian Academy of Sciences (India)

    New two-fluid (localized + band electron) model for manganites · Slide 19 · Picturizing the ferro-insulator to ferro-metal transition and the 2-fluid model · Material Systematics (varying Do) ( For fixed EJT = 0.5 eV , U = 5 eV, JF ~ (Do)2 ) · Real space structure in the presence of long range Coulomb interactions · Slide 23.

  20. Marketing planning: state of the art in a transitional economy

    OpenAIRE

    Marjanova Jovanov, Tamara; Temjanovski, Riste; Fotov, Risto

    2014-01-01

    This paper is provoked by the distorted marketing practices of companies that operate in a transitional economy, specifically Republic of Macedonia. The analysis has two main purposes: 1. to identify the weaknesses in the marketing planning process, 2. to prove the connection of continuous formal marketing planning with business performance, i.e. profitability and market share. Data was obtained from primary and secondary research. Primary research was conducted in the food, i.e. confectioner...

  1. Liquid state properties of certain noble and transition metals

    International Nuclear Information System (INIS)

    Bhuiyan, G.M.; Rahman, A.; Khaleque, M.A.; Rashid, R.I.M.A.; Mujibur Rahman, S.M.

    1998-07-01

    Certain structural, thermodynamic and atomic transport properties of a number of liquid noble and transition metals are reported. The underlying theory combines together a simple form of the N-body potential and the thermodynamically self-consistent variational modified hypernetted chain (VMHNC) theory of liquid. The static structure factors calculated by using the VMHNC resemble the hard sphere (HS) values. Consequently the HS model is used to calculate the thermodynamic properties viz. specific heat, entropy, isothermal compressibility and atomic transport properties. (author)

  2. Hydrothermal synthesis of single crystals of transition metal vanadates in the glaserite phase

    Energy Technology Data Exchange (ETDEWEB)

    Sanjeewa, Liurukara D.; McMillen, Colin D.; Willett, Daniel; Chumanov, George; Kolis, Joseph W., E-mail: kjoseph@clemson.edu

    2016-04-15

    A series of transition metal vanadate crystals were prepared using a high temperature (580 °C) hydrothermal method. The compounds all had the general formula A{sub 2}AEM(VO{sub 4}){sub 2} (A=K, Na, Li; AE=Ba, Sr; M=Co, Fe, Mn). They are all variations of the glaserite structural type and range in symmetry from P-3m1 to P-3 to P2{sub 1}/c. Most of the derivatives contain a planar three-fold rotation operation, making them possible spin frustration candidates. Single crystal structural analyses were performed on many of the derivatives to obtain a detailed understanding of the distortions of the tetrahedral building blocks that accommodate the symmetry distortions. A hydrothermal growth method was developed to grow high quality single crystals of sizes up to 2–3 mm/edge. This method can be generalized for large crystal growth to enable magnetic and neutron diffraction studies that require relatively large single crystals. - Highlights: • The hydrothermal synthesis of glaserite-type vanadates is demonstrated. • Synthesis from stoichiometric component reactions yields 0.2–0.5 mm size crystals. • Hydrothermal recrystallization of glaserite powder yields 2–3 mm size crystals. • The structure varies according to the alkali and alkaline earth metals selected. • Ideal (P-3m1) and distorted (P-3 and P2{sub 1}/c) glaserite structures are observed.

  3. Transition from many domain to single domain martensite morphology in small-scale shape memory alloys

    International Nuclear Information System (INIS)

    Ueland, Stian M.; Schuh, Christopher A.

    2013-01-01

    The morphology of the martensitic transformation during a superelastic cycle is studied by in situ scanning electron microscopy deformation experiments in microwires of Cu–Zn–Al. The diameters of the wires studied (21–136 μm) span the range in which significant size effects upon transformation hysteresis have been observed. In larger wires the transformation is accommodated by the continual nucleation of many new martensite plates that grow and eventually coalesce with their neighbors. In small wires a single martensite plate nucleates at the start of transformation and then proceeds to grow in a monolithic fashion; the wire transforms by smooth axial propagation of a single interface. The transition from many domain to single domain transformation is gradual with wire diameter, and is based upon scaling of the domain density with sample size. We attribute it to a crossover from bulk to surface obstacle control of transformation front propagation. This observation also sheds light on reported size effects in energy dissipation in shape memory alloys

  4. State and Federal project development procedures for bus rapid transit : managing differences and reducing implementation delays

    Science.gov (United States)

    2011-08-01

    This report documents an investigation into the transportation project development process in the : context of the implementation of bus rapid transit systems on the State Highway System as well as such : systems being part of the Federal New Starts ...

  5. Determining Transition State Geometries in Liquids Using 2D-IR

    Energy Technology Data Exchange (ETDEWEB)

    Harris, Charles; Cahoon, James F.; Sawyer, Karma R.; Schlegel, Jacob P.; Harris, Charles B.

    2007-12-11

    Many properties of chemical reactions are determined by the transition state connecting reactant and product, yet it is difficult to directly obtain any information about these short-lived structures in liquids. We show that two-dimensional infrared (2D-IR) spectroscopy can provide direct information about transition states by tracking the transformation of vibrational modes as a molecule crossed a transition state. We successfully monitored a simple chemical reaction, the fluxional rearrangement of Fe(CO)5, in which the exchange of axial and equatorial CO ligands causes an exchange of vibrational energy between the normal modes of the molecule. This energy transfer provides direct evidence regarding the time scale, transition state, and mechanism of the reaction.

  6. Enhancing pairwise state-transition weights: A new weighting scheme in simulated tempering that can minimize transition time between a pair of conformational states

    Science.gov (United States)

    Qiao, Qin; Zhang, Hou-Dao; Huang, Xuhui

    2016-04-01

    Simulated tempering (ST) is a widely used enhancing sampling method for Molecular Dynamics simulations. As one expanded ensemble method, ST is a combination of canonical ensembles at different temperatures and the acceptance probability of cross-temperature transitions is determined by both the temperature difference and the weights of each temperature. One popular way to obtain the weights is to adopt the free energy of each canonical ensemble, which achieves uniform sampling among temperature space. However, this uniform distribution in temperature space may not be optimal since high temperatures do not always speed up the conformational transitions of interest, as anti-Arrhenius kinetics are prevalent in protein and RNA folding. Here, we propose a new method: Enhancing Pairwise State-transition Weights (EPSW), to obtain the optimal weights by minimizing the round-trip time for transitions among different metastable states at the temperature of interest in ST. The novelty of the EPSW algorithm lies in explicitly considering the kinetics of conformation transitions when optimizing the weights of different temperatures. We further demonstrate the power of EPSW in three different systems: a simple two-temperature model, a two-dimensional model for protein folding with anti-Arrhenius kinetics, and the alanine dipeptide. The results from these three systems showed that the new algorithm can substantially accelerate the transitions between conformational states of interest in the ST expanded ensemble and further facilitate the convergence of thermodynamics compared to the widely used free energy weights. We anticipate that this algorithm is particularly useful for studying functional conformational changes of biological systems where the initial and final states are often known from structural biology experiments.

  7. Enhancing pairwise state-transition weights: A new weighting scheme in simulated tempering that can minimize transition time between a pair of conformational states

    International Nuclear Information System (INIS)

    Qiao, Qin; Zhang, Hou-Dao; Huang, Xuhui

    2016-01-01

    Simulated tempering (ST) is a widely used enhancing sampling method for Molecular Dynamics simulations. As one expanded ensemble method, ST is a combination of canonical ensembles at different temperatures and the acceptance probability of cross-temperature transitions is determined by both the temperature difference and the weights of each temperature. One popular way to obtain the weights is to adopt the free energy of each canonical ensemble, which achieves uniform sampling among temperature space. However, this uniform distribution in temperature space may not be optimal since high temperatures do not always speed up the conformational transitions of interest, as anti-Arrhenius kinetics are prevalent in protein and RNA folding. Here, we propose a new method: Enhancing Pairwise State-transition Weights (EPSW), to obtain the optimal weights by minimizing the round-trip time for transitions among different metastable states at the temperature of interest in ST. The novelty of the EPSW algorithm lies in explicitly considering the kinetics of conformation transitions when optimizing the weights of different temperatures. We further demonstrate the power of EPSW in three different systems: a simple two-temperature model, a two-dimensional model for protein folding with anti-Arrhenius kinetics, and the alanine dipeptide. The results from these three systems showed that the new algorithm can substantially accelerate the transitions between conformational states of interest in the ST expanded ensemble and further facilitate the convergence of thermodynamics compared to the widely used free energy weights. We anticipate that this algorithm is particularly useful for studying functional conformational changes of biological systems where the initial and final states are often known from structural biology experiments.

  8. Enhancing pairwise state-transition weights: A new weighting scheme in simulated tempering that can minimize transition time between a pair of conformational states

    Energy Technology Data Exchange (ETDEWEB)

    Qiao, Qin, E-mail: qqiao@ust.hk; Zhang, Hou-Dao [Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon (Hong Kong); Huang, Xuhui, E-mail: xuhuihuang@ust.hk [Department of Chemistry, Division of Biomedical Engineering, Center of Systems Biology and Human Health, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon (Hong Kong); The HKUST Shenzhen Research Institute, Shenzhen (China)

    2016-04-21

    Simulated tempering (ST) is a widely used enhancing sampling method for Molecular Dynamics simulations. As one expanded ensemble method, ST is a combination of canonical ensembles at different temperatures and the acceptance probability of cross-temperature transitions is determined by both the temperature difference and the weights of each temperature. One popular way to obtain the weights is to adopt the free energy of each canonical ensemble, which achieves uniform sampling among temperature space. However, this uniform distribution in temperature space may not be optimal since high temperatures do not always speed up the conformational transitions of interest, as anti-Arrhenius kinetics are prevalent in protein and RNA folding. Here, we propose a new method: Enhancing Pairwise State-transition Weights (EPSW), to obtain the optimal weights by minimizing the round-trip time for transitions among different metastable states at the temperature of interest in ST. The novelty of the EPSW algorithm lies in explicitly considering the kinetics of conformation transitions when optimizing the weights of different temperatures. We further demonstrate the power of EPSW in three different systems: a simple two-temperature model, a two-dimensional model for protein folding with anti-Arrhenius kinetics, and the alanine dipeptide. The results from these three systems showed that the new algorithm can substantially accelerate the transitions between conformational states of interest in the ST expanded ensemble and further facilitate the convergence of thermodynamics compared to the widely used free energy weights. We anticipate that this algorithm is particularly useful for studying functional conformational changes of biological systems where the initial and final states are often known from structural biology experiments.

  9. FCNC Bs and Λb transitions: Standard model versus a single universal extra dimension scenario

    International Nuclear Information System (INIS)

    Colangelo, P.; De Fazio, F.; Ferrandes, R.; Pham, T. N.

    2008-01-01

    We study the flavor changing neutral current B s →φγ, φνν and Λ b →Λγ, Λνν transitions in the standard model and in a scenario with a single universal extra dimension. In particular, we focus on the present knowledge of the hadronic uncertainties and on possible improvements. We discuss how the measurements of these modes can be used to constrain the new parameter involved in the extra-dimensional scenario, the radius R of the extra dimension, completing the information available from B-factories. The rates of these b→s induced decays are within the reach of new experiments, such as LHCb.

  10. Single-Cell Analysis Identifies Distinct Stages of Human Endothelial-to-Hematopoietic Transition

    Directory of Open Access Journals (Sweden)

    Carolina Guibentif

    2017-04-01

    Full Text Available During development, hematopoietic cells originate from endothelium in a process known as endothelial-to-hematopoietic transition (EHT. To study human EHT, we coupled flow cytometry and single-cell transcriptional analyses of human pluripotent stem cell-derived CD34+ cells. The resulting transcriptional hierarchy showed a continuum of endothelial and hematopoietic signatures. At the interface of these two signatures, a unique group of cells displayed both an endothelial signature and high levels of key hematopoietic stem cell-associated genes. This interphase group was validated via sort and subculture as an immediate precursor to hematopoietic cells. Differential expression analyses further divided this population into subgroups, which, upon subculture, showed distinct hematopoietic lineage differentiation potentials. We therefore propose that immediate precursors to hematopoietic cells already have their hematopoietic lineage restrictions defined prior to complete downregulation of the endothelial signature. These findings increase our understanding of the processes of de novo hematopoietic cell generation in the human developmental context.

  11. Tensile loading induced phase transition and rippling in single-layer MoS2

    Science.gov (United States)

    Bao, Hongwei; Huang, Yuhong; Yang, Zhi; Miao, Yaping; Chu, Paul K.; Xu, Kewei; Ma, Fei

    2017-05-01

    Molecular dynamics (MD) simulation is performed to study the structural evolution of single-layer MoS2 nanosheets under tensile loading and a phase transition from hexagonal structure to quadrilateral one is observed at a large strain when loaded along the zigzag direction but not along the armchair direction. Density functional theory (DFT) calculation illustrates that the newly generated quadrilateral phase is metallic. Further loading along the zigzag direction promotes an inhomogeneous distribution of lateral and shear stress around the phase boundaries due to local mechanical mismatch. As a result, periodic rippling parallel to the loading direction emerges and the wavelength and wave height change with strain according to λ∼ε-1/4 and h∼ε1/4. Accordingly, a graded distribution of strain can be produced or modulated by a simple tensile loading and the strategy might be utilized to enhance the photoelectrical properties of 2D materials and design strain-tunable nanodevices.

  12. Effect of pressure on the metamagnetic transition of DyB{sub 6} single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Sakai, T. [Department of General Education, Ariake National College of Tecnology, Omuta, Fukuoka 836-8585 (Japan)]. E-mail: sakai@ariake-nct.ac.jp; Oomi, G. [Department of Physics, Kyushu University, Ropponmatsu, Fukuoka 810-8560 (Japan); Uwatoko, Y. [Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581 (Japan); Kunii, S. [Department of Physics, Tohoku University, Sendai, Miyagi 980-8578 (Japan)

    2007-03-15

    The effects of pressure on the magnetization (M) and the magnetostriction (MS) for DyB{sub 6} single crystal have been measured at 4.2 K. It is found that the M loops are insensitive to pressure, whereas the large MS with magnitude of 0.5% at 5 T at ambient pressure is rapidly suppressed by applying pressure. The metamagnetic transition field H {sub M} in the M curve increases slightly by applying pressure with the rate of increase, {partial_derivative} ln H {sub M}/{partial_derivative}P, of 0.03 GPa{sup -1}, which is almost the same value as that for T {sub N}, 0.04 GPa{sup -1}.

  13. Modeling of charge-transfer transitions and excited states in d6 transition metal complexes by DFT techniques

    Czech Academy of Sciences Publication Activity Database

    Vlček, Antonín; Záliš, Stanislav

    2007-01-01

    Roč. 251, 3-4 (2007), s. 258-287 ISSN 0010-8545 R&D Projects: GA MŠk 1P05OC068; GA MŠk OC 139 Institutional research plan: CEZ:AV0Z40400503 Keywords : charge-transfer transition * DFT technique * excited states * spectroscopy Subject RIV: CG - Electrochemistry Impact factor: 8.568, year: 2007

  14. New transition in the vortex liquid state of YBa2Cu3O7-δ

    International Nuclear Information System (INIS)

    Kwok, Wai-Kwong; Karapetrov, Goran; Welp, Ulrich; Rydh, Andreas; Crabtree, George W.; Paulius, Lisa; Figueras, Jordi; Puig, Teresa; Obradors, X.

    2006-01-01

    We have carried out angular dependent magneto-transport measurements on optimally doped, untwinned YBa 2 Cu 3 O 7-δ crystals irradiated with high energy heavy ions to determine the onset of vortex line tension in the vortex liquid state. The dose matching field was controlled and kept at a low level to partially preserve the first order vortex lattice melting transition. A Bose glass transition is observed below the lower critical point which then transforms into a first order phase transition near 4 T. We find that the locus of points which indicates the onset of vortex line tension overlaps with the Bose glass transition line at low fields and then deviates at higher fields, indicating a new transition line in the vortex liquid state. This new line in the vortex liquid phase is dose independent and extends beyond the upper critical point

  15. 3D spin-flop transition in enhanced 2D layered structure single crystalline TlCo2Se2

    Science.gov (United States)

    Jin, Z.; Xia, Z.-C.; Wei, M.; Yang, J.-H.; Chen, B.; Huang, S.; Shang, C.; Wu, H.; Zhang, X.-X.; Huang, J.-W.; Ouyang, Z.-W.

    2016-10-01

    The enhanced 2D layered structure single crystalline TlCo2Se2 has been successfully fabricated, which exhibits field-induced 3D spin-flop phase transitions. In the case of the magnetic field parallel to the c-axis (B//c), the applied magnetic field induces the evolution of the noncollinear helical magnetic coupling into a ferromagnetic (FM) state with all the magnetization of the Co ion parallel to the c-axis. A striking variation of the field-induced strain within the ab-plane is noticed in the magnetic field region of 20-30 T. In the case of the magnetic field perpendicular to the c-axis (B  ⊥  c), the inter-layer helical antiferromagnetic (AFM) coupling may transform to an initial canted AFM coupling, and then part of it transforms to an intermediate metamagnetic phase with the alignment of two-up-one-down Co magnetic moments and finally to an ultimate FM coupling in higher magnetic fields. The robust noncollinear AFM magnetic coupling is completely destroyed above 30 T. In combination with the measurements of magnetization, magnetoresistance and field-induced strain, a complete magnetic phase diagram of the TlCo2Se2 single crystal has been depicted, demonstrating complex magnetic structures even though the crystal geometry itself gives no indication of the magnetic frustration.

  16. Hydrogen-assisted laser-induced resonant transitions between metastable states of antiprotonic helium atoms

    International Nuclear Information System (INIS)

    Ketzer, B.; Hartmann, F.J.; Egidy, T. von

    1996-11-01

    Laser resonance transitions between normally metastable states of antiprotonic helium atoms were observed making use of state dependent quenching effects caused by small admixtures of H 2 molecules. By selectively shortening the lifetimes of states with higher principal quantum number n as compared to those of lower n, this method for the first time provides access to all initially populated metastable states of p-bar He + atoms. This was demonstrated by observing the transitions (n,l) = (38,l) → (39,l+1), l 35, 36, 37 and (n,l) = (37,l) → (38,l+1), l = 34, 35, 36. (author)

  17. Hydrogen-assisted laser-induced resonant transitions between metastable states of antiprotonic helium atoms

    CERN Document Server

    Ketzer, B; Von Egidy, T; Maierl, C; Pohl, R; Eades, John; Widmann, E; Yamazaki, T; Kumakura, M; Morita, N; Hayano, R S; Hori, Masaki; Ishikawa, T; Torii, H A; Sugai, I; Horváth, D

    1997-01-01

    Laser resonance transitions between normally metastable states of antiprotonic helium atoms were observed making use of state dependent quenching effects caused by small admixtures of \\htwo\\ molecules. By selectively shortening the lifetimes of states with higher principal quantum number $n$ as compared to those of lower $n$, this method for the first time provides access to all initially populated metastable states of \\pbar\\hep\\ atoms. This was demonstrated by observing the transitions $(n,l)=(38,l)\\rightarrow (39,l+1),\\ l=35,36,37$ and $(n,l)=(37,l)\\rightarrow (38,l+1),\\ l=34,35,36$.

  18. Malaysia’s 2008 General Election – Transition from Single-party Dominance?

    Directory of Open Access Journals (Sweden)

    William Case

    2010-01-01

    Full Text Available Leading theories of transitions from single-party dominant systems begin with economic crisis, the party’s loss of patronage resources, and elite-level defections. The multiparty elections that are then held exert no independent effect, but instead register neutrally the party’s decline and the democratization of politics. This paper, however, shifts attention from the dominant party to citizens and elections in non-crisis conditions. It argues that on key dimensions citizens assess the dominant party’s legitimacy or worthiness of support. Further, where they grow critical of its policy outputs, they scrutinize more closely its conformity to procedures. And as they anticipate that their voting preferences will be thwarted by electoral manipulations, they vote in protest, perhaps producing a “liberalizing electoral outcome.” Elections, then, do not simply indicate the dominant party’s decline. By deepening alienation, they help citizens to cause it. Analysis is set in Malaysia, long an exemplar of single-party dominance, but recently a case in which the government was dealt a striking electoral setback.

  19. Morphology of single inhalable particle inside public transit biodiesel fueled bus.

    Science.gov (United States)

    Shandilya, Kaushik K; Kumar, Ashok

    2010-01-01

    In an urban-transit bus, fueled by biodiesel in Toledo, Ohio, single inhalable particle samples in October 2008 were collected and detected by scanning electron microscopy and energy dispersive X-ray spectrometry (SEM/EDS). Particle size analysis found bimodal distribution at 0.2 and 0.5 microm. The particle morphology was characterized by 14 different shape clusters: square, pentagon, hexagon, heptagon, octagon, nonagon, decagon, agglomerate, sphere, triangle, oblong, strip, line or stick, and unknown, by quantitative order. The square particles were common in the samples. Round and triangle particles are more, and pentagon, hexagon, heptagon, octagon, nonagon, decagon, strip, line or sticks are less. Agglomerate particles were found in abundance. The surface of most particles was coarse with a fractal edge that can provide a suitable chemical reaction bed in the polluted atmospheric environment. The three sorts of surface patterns of squares were smooth, semi-smooth, and coarse. The three sorts of square surface patterns represented the morphological characteristics of single inhalable particles in the air inside the bus in Toledo. The size and shape distribution results were compared to those obtained for a bus using ultra low sulfur diesel.

  20. Study of Transitions between Wetting States on Microcavity Arrays by Optical Transmission Microscopy

    DEFF Research Database (Denmark)

    Søgaard, Emil; Andersen, Nis Korsgaard; Smistrup, Kristian

    2014-01-01

    In this article, we present a simple and fast optical method based on transmission microscopy to study the stochastic wetting transitions on micro- and nanostructured polymer surfaces immersed in water. We analyze the influence of immersion time and the liquid pressure on the degree of water...... this threshold, the transitions between the Cassie and the Cassie-impregnating states are reversible, whereas above this threshold, irreversible transitions to the Wenzel state start to occur. The transitions between the different wetting states can be explained by taking into account both the Young-Laplace...... compared the contact angle properties of two polymeric materials (COC and PP) with moderate hydrophobicity. We attributed the difference in the water repellency of the two materials to a difference in the wetting of their nanostructures. Our experimental observations thus indicate that both the diffusion...

  1. Evidence from n=2 fine structure transitions for the production of fast excited state positronium

    International Nuclear Information System (INIS)

    Ley, R.; Niebling, K.D.; Schwarz, R.; Werth, G.

    1990-01-01

    Fine structure transitions in the first excited state of positronium (Ps) have been measured using 'Backscatter Ps' production on a Mo surface by observation of a change in the emitted Lyman-α intensity under resonant microwave irradiation. Production, fine structure transitions and Lyman-α decay of the Ps atoms took place inside a waveguide designed to transmit the microwave frequencies of 8.6, 13.0 and 18.5 GHz for the transitions from the 2 3 S 1 state to the 2 3 P J , J=2, 1, 0, states, respectively. In the presence of a magnetic field, all transitions observed show a shift to higher frequencies, compared with earlier calculations and measurements in zero magnetic field. The deviations exceed the expected Zeeman shift significantly but may be explained by assuming a motional Stark effect for Ps with kinetic energies of several eV. (author)

  2. Shape transition of state density for bosonic systems

    Indian Academy of Sciences (India)

    ... while the shape of the state density for EGOE(2) with m ≫ 2, is close to Gaussian. The change in shape of the state density, from semicircle to Gaussian for EGOE(k), as m increases from k to m ≫ k for fermions, has been explained mathematically by Mon and French [4] and also by Benet. Pramana – J. Phys., Vol. 81, No.

  3. A modified PATH algorithm rapidly generates transition states comparable to those found by other well established algorithms

    Directory of Open Access Journals (Sweden)

    Srinivas Niranj Chandrasekaran

    2016-01-01

    Full Text Available PATH rapidly computes a path and a transition state between crystal structures by minimizing the Onsager-Machlup action. It requires input parameters whose range of values can generate different transition-state structures that cannot be uniquely compared with those generated by other methods. We outline modifications to estimate these input parameters to circumvent these difficulties and validate the PATH transition states by showing consistency between transition-states derived by different algorithms for unrelated protein systems. Although functional protein conformational change trajectories are to a degree stochastic, they nonetheless pass through a well-defined transition state whose detailed structural properties can rapidly be identified using PATH.

  4. Growth of tourmaline single crystals containing transition metal elements in hydrothermal solutions

    Science.gov (United States)

    Setkova, Tatiana; Shapovalov, Yury; Balitsky, Vladimir

    2011-03-01

    Interest in the growth of tourmaline single crystals is based on the promising piezoelectric and pyroelectric properties of this material compared to quartz crystals currently in use. Moreover, synthetic tourmaline can be used as a substitute for the natural stone in the jewelry industry similar to other synthetic analogues of gemstones. Single crystals of colored Co-, Ni-, Fe-, (Ni,Cr)-, (Ni,Fe)-, and (Co,Ni,Cr)-containing tourmalines with concentration of transition metal elements up to 16 wt% on a seed have been grown from complex boron-containing hydrothermal solutions at a range of temperatures 400-750 °C and pressures 100 MPa. Experiments were conducted under conditions of a thermal gradient in titanium and chromium-nickel autoclaves. Tourmaline growth on a seed crystal occurs only if separate tourmaline-forming components (monocrystalline corundum and quartz bars) are used as charge. All tourmalines specified above grow in analogous (+) direction of the optical axis with a speed of 0.05 mm/day by faces of the trigonal pyramid, except tourmalines containing chromium. They grow in analogous (+0001) direction with a speed 0.05 mm/day, and in antilogous (-0001) direction with a speed of 0.01 mm/day by faces of the trigonal pyramid and in prism direction with a speed of 0.001 mm/day. Along with the large single crystals, a great amount of finest (30-150 μm in size) tourmaline crystals was formed during the runs by spontaneous nucleation both on the surface of the seed crystals and in the charge.

  5. Single-column model and large eddy simulation of the evening transition in the planetary boundary layer

    Science.gov (United States)

    Cuchiara, Gustavo; Rappenglück, Bernhard

    2016-04-01

    The transition from the convective boundary layer during the daytime to the stable stratified boundary layer during nighttime after sunset plays an important role in the transport and dispersion of atmospheric pollutants. However, our knowledge regarding this transition and its feedback on the structure of the subsequent nocturnal boundary layer is still restricted. This also prevents forecast models from accurate prediction of the onset and development of the nighttime boundary layer, which determines the redistribution of pollutants within the nocturnal surface layer and the residual layer aloft. In the present study, the well-known case of day 33 of the Wangara experiment is resimulated using the Weather Research and Forecasting (WRF) model in an idealized single-column mode to assess the performance of a frequently used planetary boundary layer (PBL) scheme, the Yonsei University (YSU) PBL scheme. These results are compared with two large eddy simulations (LES) for the same case study imposing different surface fluxes: one using previous surface fluxes calculated for the Wangara experiment and a second one using output from the WRF model. The results show a reasonable agreement of the PBL scheme in WRF with the LES. Overall, all the simulations presented a cold bias of ~3 Kelvin for the potential temperature and underestimation of the wind speed, especially after the transition to nighttime conditions (biases were up to 4 ms-1). Finally, an alternative set of eddy diffusivity equations was tested to represent the transition characteristics of a sunset period, with a stable layer below and a new parameterization for the convective decay regime typically observed in the RL aloft. This set of equations led to a gradual decrease of the eddy diffusivity, which replaces the instantaneous collapse of traditional diagnostics for eddy diffusivities. More appreciable changes were observed in air temperature, wind speed and specific humidity (up to 0.5 K, 0.6 ms-1, and 0

  6. Quantum phase transitions between a class of symmetry protected topological states

    Energy Technology Data Exchange (ETDEWEB)

    Tsui, Lokman; Jiang, Hong-Chen; Lu, Yuan-Ming; Lee, Dung-Hai

    2015-07-01

    The subject of this paper is the phase transition between symmetry protected topological states (SPTs). We consider spatial dimension d and symmetry group G so that the cohomology group, Hd+1(G,U(1)), contains at least one Z2n or Z factor. We show that the phase transition between the trivial SPT and the root states that generate the Z2n or Z groups can be induced on the boundary of a (d+1)-dimensional View the MathML source-symmetric SPT by a View the MathML source symmetry breaking field. Moreover we show these boundary phase transitions can be “transplanted” to d dimensions and realized in lattice models as a function of a tuning parameter. The price one pays is for the critical value of the tuning parameter there is an extra non-local (duality-like) symmetry. In the case where the phase transition is continuous, our theory predicts the presence of unusual (sometimes fractionalized) excitations corresponding to delocalized boundary excitations of the non-trivial SPT on one side of the transition. This theory also predicts other phase transition scenarios including first order transition and transition via an intermediate symmetry breaking phase.

  7. TRANSIT

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. TRANSIT. SYSTEM: DETERMINE 2D-POSITION GLOBALLY BUT INTERMITTENT (POST-FACTO). IMPROVED ACCURACY. PRINCIPLE: POLAR SATELLITES WITH INNOVATIONS OF: GRAVITY-GRADIENT ATTITUDE CONTROL; DRAG COMPENSATION. WORKS ...

  8. Changes in Single K+ Channel Behavior Induced by a Lipid Phase Transition

    Science.gov (United States)

    Seeger, Heiko M.; Aldrovandi, Laura; Alessandrini, Andrea; Facci, Paolo

    2010-01-01

    We show that the activity of an ion channel is correlated with the phase state of the lipid bilayer hosting the channel. By measuring unitary conductance, dwell times, and open probability of the K+ channel KcsA as a function of temperature in lipid bilayers composed of POPE and POPG in different relative proportions, we obtain that all those properties show a trend inversion when the bilayer is in the transition region between the liquid-disordered and the solid-ordered phase. These data suggest that the physical properties of the lipid bilayer influence ion channel activity likely via a fine-tuning of its conformations. In a more general interpretative framework, we suggest that other parameters such as pH, ionic strength, and the action of amphiphilic drugs can affect the physical behavior of the lipid bilayer in a fashion similar to temperature changes resulting in functional changes of transmembrane proteins. PMID:21112292

  9. Travel Patterns And Characteristics Of Transit Users In New York State

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Ho-Ling [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Wilson, Daniel W. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Reuscher, Tim [Macrosys, Arlington, VA (United States); Chin, Shih-Miao [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Taylor, Rob D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-12-01

    This research is a detailed examination of the travel behaviors and patterns of transit users within New York State (NYS), primarily based on travel data provided by the National Household Travel Survey (NHTS) in 2009 and the associated Add-on sample households purchased by the New York State Department of Transportation (NYSDOT). Other data sources analyzed in this study include: NYS General Transit Feed Specification (GTFS) to assist in analyzing spatial relationships for access to transit and the creation of Transit Shed geographic areas of 1, 2.5, and 5 miles from transit stop locations, LandScan population database to understand transit coverage, and Census Bureau s American Community Survey (ACS) data to examine general transit patterns and trends in NYS over time. The majority of analyses performed in this research aimed at identifying transit trip locations, understanding differences in transit usage by traveler demographics, as well as producing trip/mode-specific summary statistics including travel distance, trip duration, time of trip, and travel purpose of transit trips made by NYS residents, while also analyzing regional differences and unique travel characteristics and patterns. The analysis was divided into two aggregated geographic regions: New York Metropolitan Transportation Council (NYMTC) and NYS minus NYMTC (Rest of NYS). The inclusion of NYMTC in all analysis would likely produce misleading conclusions for other regions in NYS. TRANSIT COVERAGE The NYS transit network has significant coverage in terms of transit stop locations across the state s population. Out of the 19.3 million NYS population in 2011, about 15.3 million (or 79%) resided within the 1-mile transit shed. This NYS population transit coverage increased to 16.9 million (or 88%) when a 2.5-mile transit shed was considered; and raised to 17.7 million (or 92%) when the 5-mile transit shed was applied. KEY FINDINGS Based on 2009 NHTS data, about 40% of NYMTC households used transit

  10. Performance of TD-DFT for Excited States of Open-Shell Transition Metal Compounds.

    Science.gov (United States)

    Suo, Bingbing; Shen, Kaiyuan; Li, Zhendong; Liu, Wenjian

    2017-05-25

    Time-dependent density functional theory (TD-DFT) has been very successful in accessing low-lying excited states of closed-shell systems. However, it is much less so for excited states of open-shell systems: unrestricted Kohn-Sham based TD-DFT (U-TD-DFT) often produces physically meaningless excited states due to heavy spin contaminations, whereas restricted Kohn-Sham based TD-DFT often misses those states of lower energies. A much better variant is the explicitly spin-adapted TD-DFT (X-TD-DFT) [J. Chem. Phys. 2011, 135, 194106] that can capture all the spin-adapted singly excited states yet without computational overhead over U-TD-DFT. While the superiority of X-TD-DFT over U-TD-DFT has been demonstrated for open-shell systems of main group elements, it remains to be seen if this is also the case for open-shell transition metal compounds. Taking as benchmark the results by MS-CASPT2 (multistate complete active space second-order perturbation theory) and ic-MRCISD (internally contracted multireference configuration interaction with singles and doubles), it is shown that X-TD-DFT is indeed superior to U-TD-DFT for the vertical excitation energies of ZnH, CdH, ScH 2 , YH 2 , YO, and NbO 2 . Admittedly, there exist a few cases where U-TD-DFT appears to be better than X-TD-DFT. However, this is due to a wrong reason: the underestimation (due to spin contamination) and the overestimation (due to either the exchange-correlation functional itself or the adiabatic approximation to the exchange-correlation kernel) happen to be compensated in the case of U-TD-DFT. As for [Cu(C 6 H 6 ) 2 ] 2+ , which goes beyond the capability of both MS-CASPT2 and ic-MRCISD, X-TD-DFT revises the U-TD-DFT assignment of the experimental spectrum.

  11. Structural Operational Semantics for Continuous State Stochastic Transition Systems

    DEFF Research Database (Denmark)

    Bacci, Giorgio; Miculan, Marino

    2015-01-01

    In this paper we show how to model syntax and semantics of stochastic processes with continuous states, respectively as algebras and coalgebras of suitable endofunctors over the category of measurable spaces Meas. Moreover, we present an SOS-like rule format, called MGSOS , representing abstract ...

  12. Rapid Communication: seniority changing transitions in yrast states ...

    Indian Academy of Sciences (India)

    Bhoomika Maheshwari

    2017-10-26

    Oct 26, 2017 ... of seniority has proved to be a powerful tool in explor- ing nuclei close to the magic numbers, and may also be related to the symmetry in pairing of nucleons. The seniority scheme was first introduced by Racah [1] in the atomic context to distinguish the states having same values of L, S and J in LS coupling, ...

  13. Shape transition of state density for bosonic systems

    Indian Academy of Sciences (India)

    density for EGOE(2) with m ≫ 2, is close to Gaussian. The change in shape of the state density, from semicircle to Gaussian for EGOE(k), as m increases from k to m ≫ k for fermions, has been explained mathematically by Mon and French [4] and also by Benet. Pramana – J. Phys., Vol. 81, No. 6, December 2013. 1045 ...

  14. State Isomorphism in the Post-Socialist Transition

    Directory of Open Access Journals (Sweden)

    Ioannis Kyvelidis

    2000-02-01

    Full Text Available With the collapse of the communist regimes, the post-socialist countries are facing the problem of building new legal and institutional systems which will adequately address the needs of the markets. They also try to implement new reforms. But the transition towards economic and market reforms across the bloc has been very uneven, producing the countries-winners, countries-laggards, and countries-losers. There have been some attempts to explain that unevenness from the temporal path dependency perspective and from geographic proximity perspective. Can we explain this unevenness better drawing upon the theory of institutional isomorphism? This paper is not ambitious and built exclusively on literature review. It attempts to borrow from some middle-range social theories of institution building and, especially, the theory of institutional isomorphism by DiMaggio and Powell. It shows that some parts of the bloc seem to be surprisingly isomorphic. The paper suggests an explanation of the possible causes and applicability of the phenomenon of isomorphism in the post-Soviet bloc. In particular, it: 1 contrasts the facts of the transformation with the theory of institutional and organizational isomorphism, 2 makes a fair causal comparison with other explanations, 3 claims the adequate causal depth for the explanation, 4 points at an adequate causal mechanism of the transformation.

  15. Two states or not two states: Single-molecule folding studies of protein L

    Science.gov (United States)

    Aviram, Haim Yuval; Pirchi, Menahem; Barak, Yoav; Riven, Inbal; Haran, Gilad

    2018-03-01

    Experimental tools of increasing sophistication have been employed in recent years to study protein folding and misfolding. Folding is considered a complex process, and one way to address it is by studying small proteins, which seemingly possess a simple energy landscape with essentially only two stable states, either folded or unfolded. The B1-IgG binding domain of protein L (PL) is considered a model two-state folder, based on measurements using a wide range of experimental techniques. We applied single-molecule fluorescence resonance energy transfer (FRET) spectroscopy in conjunction with a hidden Markov model analysis to fully characterize the energy landscape of PL and to extract the kinetic properties of individual molecules of the protein. Surprisingly, our studies revealed the existence of a third state, hidden under the two-state behavior of PL due to its small population, ˜7%. We propose that this minority intermediate involves partial unfolding of the two C-terminal β strands of PL. Our work demonstrates that single-molecule FRET spectroscopy can be a powerful tool for a comprehensive description of the folding dynamics of proteins, capable of detecting and characterizing relatively rare metastable states that are difficult to observe in ensemble studies.

  16. Designing Single-Ion Magnets and Phosphorescent Materials with 1-Methylimidazole-5-carboxylate and Transition-Metal Ions.

    Science.gov (United States)

    García-Valdivia, Antonio A; Seco, Jose M; Cepeda, Javier; Rodríguez-Diéguez, Antonio

    2017-11-20

    Detailed structural, magnetic, and photoluminescence (PL) characterization of four new compounds based on 1-methylimidazole-5-carboxylate (mimc) ligand and transition metal ions, namely [Ni(mimc) 2 (H 2 O) 4 ] (1), [Co(μ-mimc) 2 ] n (2), {[Cu 2 (μ-mimc) 4 (H 2 O)]·2H 2 O} n (3), and [Cd(μ-mimc) 2 (H 2 O)] n (4) is reported. The structural diversity found in the family of compounds derives from the coordination versatility of the ligand, which coordinates as a terminal ligand to give a supramolecular network of monomeric entities in 1 or acts as a bridging linker to build isoreticular 2D coordination polymers (CPs) in 2-4. Magnetic direct-current (dc) susceptibility data have been measured for compounds 1-3 to analyze the exchange interactions among paramagnetic centers, which have been indeed supported by calculations based on broken symmetry (BS) and density functional theory (DFT) methodology. The temperature dependence of susceptibility and magnetization data of 2 are indicative of easy-plane anisotropy (D = +12.9 cm -1 , E = +0.5 cm -1 ) that involves a bistable M s = ±1/2 ground state. Alternating-current (ac) susceptibility curves exhibit field-induced single-ion magnet (SIM) behavior that occurs below 14 K, which is characterized by two spin relaxation processes of distinct nature: fast relaxation of single ions proceeding through multiple mechanisms (U eff = 26 K) and a slow relaxation attributed to interactions along the polymeric crystal building. Exhaustive PL analysis of compound 4 in the solid state confirms low-temperature phosphorescent green emission consisting of radiative lifetimes in the range of 0.25-0.43 s, which explains the afterglow observed during about 1 s after the removal of the UV source. Time-dependent DFT and computational calculations to estimate phosphorescent vertical transitions have been also employed to provide an accurate description of the PL performance of this long-lasting phosphor.

  17. Magnetic field effect on state energies and transition frequency of a ...

    Indian Academy of Sciences (India)

    Abstract. By employing a variational method of the Pekar-type, which has different variational parameters in the x–y plane and the z-direction, we study the ground and the first excited state ener- gies and transition frequency between the ground and the first excited states of a strong-coupling polaron in an anisotropic ...

  18. Magnetic field effect on state energies and transition frequency of a ...

    Indian Academy of Sciences (India)

    By employing a variational method of the Pekar-type, which has different variational parameters in the – plane and the z -direction, we study the ground and the first excited state energies and transition frequency between the ground and the first excited states of a strong-coupling polaron in an anisotropic quantum dot ...

  19. State-and-transition models as guides for adaptive management: What are the needs?

    Science.gov (United States)

    State and transaction models (STMs) were conceived as a means to organize information about land potential and vegetation dynamics in rangelands to be used in their management. The basic idea is to describe the plant community states that can occur on a site and the causes of transitions between the...

  20. From War to Politics : Non-State Armed Groups in Transition, 2009 ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    An earlier project (103613) resulted in the creation of a research network on the experience of non-state armed groups (NSAGs) who have made the transition from armed resistance during protracted violent conflicts to political engagement in peace negotiations and post-war state building. This project will continue the ...

  1. Theoretical expression of the internal conversion coefficient of a M1 transition between two atomic states

    International Nuclear Information System (INIS)

    Attallah, F.; Chemin, J.F.; Scheurer, J.N.; Karpeshin, F.; Harston, M.

    1997-01-01

    We have established a general relation for the expression of the internal conversion of an M 1 transition a 1s electronic state to an empty ns electronic bound state. Under the hypothesis that the density of the electron level ρ n satisfies the condition ρ n Γ >> 1 (where Γ is the total width of the excited atomic state) a calculation in the first order gives a relation for the internal conversion coefficient.This relation shows that the internal conversion coefficient takes a resonant character when the nuclear energy transition is smaller than the binding energy of the 1s electron. An application of this relation to an M 1 transition in the case of the ion 125 T e with a charge state Q = 45 and an 1s electron binding energy E B 45 = 35.581 KeV gives the value for the internal conversion coefficient R = 5.7

  2. Calculating Transition Energy Barriers and Characterizing Activation States for Steps of Fusion.

    Science.gov (United States)

    Ryham, Rolf J; Klotz, Thomas S; Yao, Lihan; Cohen, Fredric S

    2016-03-08

    We use continuum mechanics to calculate an entire least energy pathway of membrane fusion, from stalk formation, to pore creation, and through fusion pore enlargement. The model assumes that each structure in the pathway is axially symmetric. The static continuum stalk structure agrees quantitatively with experimental stalk architecture. Calculations show that in a stalk, the distal monolayer is stretched and the stored stretching energy is significantly less than the tilt energy of an unstretched distal monolayer. The string method is used to determine the energy of the transition barriers that separate intermediate states and the dynamics of two bilayers as they pass through them. Hemifusion requires a small amount of energy independently of lipid composition, while direct transition from a stalk to a fusion pore without a hemifusion intermediate is highly improbable. Hemifusion diaphragm expansion is spontaneous for distal monolayers containing at least two lipid components, given sufficiently negative diaphragm spontaneous curvature. Conversely, diaphragms formed from single-component distal monolayers do not expand without the continual injection of energy. We identify a diaphragm radius, below which central pore expansion is spontaneous. For larger diaphragms, prior studies have shown that pore expansion is not axisymmetric, and here our calculations supply an upper bound for the energy of the barrier against pore formation. The major energy-requiring deformations in the steps of fusion are: widening of a hydrophobic fissure in bilayers for stalk formation, splay within the expanding hemifusion diaphragm, and fissure widening initiating pore formation in a hemifusion diaphragm. Copyright © 2016 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  3. Decoding brain state transitions in the pedunculopontine nucleus: cooperative phasic and tonic mechanisms

    Directory of Open Access Journals (Sweden)

    Anne ePetzold

    2015-10-01

    Full Text Available Cholinergic neurons of the pedunculopontine nucleus (PPN are most active during the waking state. Their activation is deemed to cause a switch in the global brain activity from sleep to wakefulness, while their sustained discharge may contribute to upholding the waking state and enhancing arousal. Similarly, non-cholinergic PPN neurons are responsive to brain state transitions and their activation may influence some of the same targets of cholinergic neurons, suggesting that they operate in coordination. Yet, it is not clear how the discharge of distinct classes of PPN neurons organize during brain states. Here we monitored the in vivo network activity of PPN neurons in the anesthetized rat across two distinct levels of cortical dynamics and their transitions. We identified a highly structured configuration in PPN network activity during slow-wave activity that was replaced by decorrelated activity during the activated state. During the transition, neurons were predominantly excited (phasically or tonically, but some were inhibited. Identified cholinergic neurons displayed phasic and short latency responses to sensory stimulation, whereas the majority of non-cholinergic showed tonic responses and remained at high discharge rates beyond the state transition. In vitro recordings demonstrate that cholinergic neurons exhibit fast adaptation that prevents them from discharging at high rates over prolonged time periods. Our data shows that PPN neurons have distinct but complementary roles during brain state transitions, where cholinergic neurons provide a fast and transient response to sensory events that drive state transitions, whereas non-cholinergic neurons maintain an elevated firing rate during global activation.

  4. Frequency tuning of single photons from a whispering-gallery mode resonator to MHz-wide transitions

    DEFF Research Database (Denmark)

    Schunk, G.; Vogl, U.; Sedlmeir, F.

    2016-01-01

    Quantum repeaters rely on interfacing flying qubits with quantum memories. The most common implementations include a narrowband single photon matched in bandwidth and central frequency to an atomic system. Previously, we demonstrated the compatibility of our versatile source of heralded single....... Finally, we present an accurate analytical description of our observations. Providing the demonstrated flexibility in connecting various atomic transitions with telecom wavelengths, we show a promising approach to realize an essential building block for quantum repeaters....

  5. Automated Transition State Searches without Evaluating the Hessian.

    Science.gov (United States)

    Mallikarjun Sharada, Shaama; Zimmerman, Paul M; Bell, Alexis T; Head-Gordon, Martin

    2012-12-11

    Accurate and speedy determination of transition structures (TSs) is essential for computational studies on reaction pathways, particularly when the process involves expensive electronic structure calculations. Many search algorithms require a good initial guess of the TS geometry, as well as a Hessian input that possesses a structure consistent with the desired saddle point. Among the double-ended interpolation methods for generation of the guess for the TS, the freezing string method (FSM) is proven to be far less expensive compared to its predecessor, the growing string method (GSM). In this paper, it is demonstrated that the efficiency of this technique can be improved further by replacing the conjugate gradient optimization step (FSM-CG) with a quasi-Newton line search coupled with a BFGS Hessian update (FSM-BFGS). A second crucial factor that affects the speed with which convergence to the TS is achieved is the quality and cost of the Hessian of the energy for the guessed TS. For electronic structure calculations, the cost of calculating an exact Hessian increases more rapidly with system size than the energy and gradient. Therefore, to sidestep calculation of the exact Hessian, an approximate Hessian is constructed, using the tangent direction and local curvature at the TS guess. It is demonstrated that the partitioned-rational function optimization algorithm for locating TSs with this approximate Hessian input performs at least as well as with an exact Hessian input in most test cases. The two techniques, FSM and approximate Hessian construction, therefore can significantly reduce costs associated with finding TSs.

  6. Transition state-finding strategies for use with the growing string method

    Science.gov (United States)

    Goodrow, Anthony; Bell, Alexis T.; Head-Gordon, Martin

    2009-06-01

    Efficient identification of transition states is important for understanding reaction mechanisms. Most transition state search algorithms require long computational times and a good estimate of the transition state structure in order to converge, particularly for complex reaction systems. The growing string method (GSM) [B. Peters et al., J. Chem. Phys. 120, 7877 (2004)] does not require an initial guess of the transition state; however, the calculation is still computationally intensive due to repeated calls to the quantum mechanics code. Recent modifications to the GSM [A. Goodrow et al., J. Chem. Phys. 129, 174109 (2008)] have reduced the total computational time for converging to a transition state by a factor of 2 to 3. In this work, three transition state-finding strategies have been developed to complement the speedup of the modified-GSM: (1) a hybrid strategy, (2) an energy-weighted strategy, and (3) a substring strategy. The hybrid strategy initiates the string calculation at a low level of theory (HF/STO-3G), which is then refined at a higher level of theory (B3LYP/6-31G∗). The energy-weighted strategy spaces points along the reaction pathway based on the energy at those points, leading to a higher density of points where the energy is highest and finer resolution of the transition state. The substring strategy is similar to the hybrid strategy, but only a portion of the low-level string is refined using a higher level of theory. These three strategies have been used with the modified-GSM and are compared in three reactions: alanine dipeptide isomerization, H-abstraction in methanol oxidation on VOx/SiO2 catalysts, and C-H bond activation in the oxidative carbonylation of toluene to p-toluic acid on Rh(CO)2(TFA)3 catalysts. In each of these examples, the substring strategy was proved most effective by obtaining a better estimate of the transition state structure and reducing the total computational time by a factor of 2 to 3 compared to the modified

  7. Minimal transition state charge stabilization of the oxyanion during peptide bond formation by the ribosome.

    Science.gov (United States)

    Carrasco, Nicolas; Hiller, David A; Strobel, Scott A

    2011-12-06

    Peptide bond formation during ribosomal protein synthesis involves an aminolysis reaction between the aminoacyl α-amino group and the carbonyl ester of the growing peptide via a transition state with a developing negative charge, the oxyanion. Structural and molecular dynamic studies have suggested that the ribosome may stabilize the oxyanion in the transition state of peptide bond formation via a highly ordered water molecule. To biochemically investigate this mechanistic hypothesis, we estimated the energetic contribution to catalytic charge stabilization of the oxyanion using a series of transition state mimics that contain different charge distributions and hydrogen bond potential on the functional group mimicking the oxyanion. Inhibitors containing an oxyanion mimic that carried a neutral charge and a mimic that preserved the negative charge but could not form hydrogen bonds had less than a 3-fold effect on inhibitor binding affinity. These observations argue that the ribosome provides minimal transition state charge stabilization to the oxyanion during peptide bond formation via the water molecule. This is in contrast to the substantial level of oxyanion stabilization provided by serine proteases. This suggests that the oxyanion may be neutralized via a proton shuttle, resulting in an uncharged transition state.

  8. A DETERMINATION OF RADIATIVE TRANSITIONS WIDTHS OF EXCITED STATES IN C(12),

    Science.gov (United States)

    the -2 power to 3.14 F to the -2 power. A new method of analysis has been employed to obtain the radiative widths for the first three excited states...in C(12) from the measured inelastic cross sections. This method of analysis does not depend on a model for the transition charge distribution and is useful in determining the multipolarity of the transition. (Author)

  9. Markov-chain model of classified atomistic transition states for discrete kinetic Monte Carlo simulations.

    Science.gov (United States)

    Numazawa, Satoshi; Smith, Roger

    2011-10-01

    Classical harmonic transition state theory is considered and applied in discrete lattice cells with hierarchical transition levels. The scheme is then used to determine transitions that can be applied in a lattice-based kinetic Monte Carlo (KMC) atomistic simulation model. The model results in an effective reduction of KMC simulation steps by utilizing a classification scheme of transition levels for thermally activated atomistic diffusion processes. Thermally activated atomistic movements are considered as local transition events constrained in potential energy wells over certain local time periods. These processes are represented by Markov chains of multidimensional Boolean valued functions in three-dimensional lattice space. The events inhibited by the barriers under a certain level are regarded as thermal fluctuations of the canonical ensemble and accepted freely. Consequently, the fluctuating system evolution process is implemented as a Markov chain of equivalence class objects. It is shown that the process can be characterized by the acceptance of metastable local transitions. The method is applied to a problem of Au and Ag cluster growth on a rippled surface. The simulation predicts the existence of a morphology-dependent transition time limit from a local metastable to stable state for subsequent cluster growth by accretion. Excellent agreement with observed experimental results is obtained.

  10. Measuring quantum-chromodynamic anomalies in hadronic transitions between quarkonium states

    Energy Technology Data Exchange (ETDEWEB)

    Voloshin, M.; Zakharov, V.

    1980-09-01

    It is argued that the ratio GAMMA((Q-barQ)'..-->..(Q-barQ)eta)/GAMMA((Q-barQ)' ..-->..(Q-barQ)..pi pi..) of hadronic transition rates between heavy quarkonium states is calculable within quantum chromodynamics in terms of triangle anaomalies in the divergence of the axial current and in the trace of the energy-momentum tensor. In the case of transitions between psi' and J/psi the present analysis is consistent with the data. More reliable test can be provided by experimental study of the transitions between UPSILON'' and UPSILON.

  11. Walk, Bicycle, and Transit Trips of Transit-Dependent and Choice Riders in the 2009 United States National Household Travel Survey.

    Science.gov (United States)

    Lachapelle, Ugo

    2015-08-01

    Previous research has shown that public transit use may be associated with active transportation. Access to a car may influence active transportation of transit riders. Using the 2009 United States National Household Travel Survey (NHTS), transit users ≥ 16 years old (n = 25,550) were categorized according to driver status and number of cars and drivers in the household. This typology ranged from choice transit riders (ie, "fully motorized drivers") to transit-dependent riders (ie, "unmotorized nondriver"). Transit trips, walking trips, and bicycling trips of transit users are estimated in negative binomial models against the car availability typology. Sixteen percent of participants took transit in the past month; most (86%) lived in car-owning households. As income increased, car availability also increased. Transit user groups with lower car availability were generally more likely than fully motorized drivers to take more public transit, walking, and bicycle trips. Transit riders have varying levels of vehicle access; their use of combinations of alternative modes of transportation fluctuates accordingly. Transit-dependent individuals without cars or sharing cars used active transportation more frequently than car owners. Policies to reduce vehicle ownership in households may enable increases in the use of alternative modes of transportation for transit users, even when cars are still owned.

  12. Structural transition, subgap states, and carrier transport in anion-engineered zinc oxynitride nanocrystalline films

    International Nuclear Information System (INIS)

    Xian, Fenglin; Ye, Jiandong; Gu, Shulin; Tan, Hark Hoe; Jagadish, Chennupati

    2016-01-01

    In this work, anion alloying is engineered in ZnON nanocrystalline films, and the resultant evolution of the structural transition, subgap states, and carrier transport is investigated. A broad distribution of sub-gap states above the valence band maximum is introduced by nitrogen due to the hybridization of N 2p and O 2p orbitals. The phase transition from partially amorphous states to full crystallinity occurs above a characteristic growth temperature of 100 °C, and the localized states are suppressed greatly due to the reduction of nitrogen composition. The electronic properties are dominated by grain boundary scattering and electron transport across boundary barriers through thermal activation at band edge states at high temperatures. The conductivity below 130 K exhibits a weak temperature dependence, which is a signature of variable-range hopping conduction between localized states introduced by nitrogen incorporation.

  13. Structural transition, subgap states, and carrier transport in anion-engineered zinc oxynitride nanocrystalline films

    Energy Technology Data Exchange (ETDEWEB)

    Xian, Fenglin [School of Physics and Optoelectronic Engineering, Nanjing University of Information Science and Technology, Nanjing 210044 (China); Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra 2601 (Australia); Ye, Jiandong, E-mail: yejd@nju.edu.cn [Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra 2601 (Australia); School of Electronics Science and Engineering, Nanjing University, Nanjing 210093 (China); Gu, Shulin [School of Electronics Science and Engineering, Nanjing University, Nanjing 210093 (China); Tan, Hark Hoe; Jagadish, Chennupati [Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra 2601 (Australia)

    2016-07-11

    In this work, anion alloying is engineered in ZnON nanocrystalline films, and the resultant evolution of the structural transition, subgap states, and carrier transport is investigated. A broad distribution of sub-gap states above the valence band maximum is introduced by nitrogen due to the hybridization of N 2p and O 2p orbitals. The phase transition from partially amorphous states to full crystallinity occurs above a characteristic growth temperature of 100 °C, and the localized states are suppressed greatly due to the reduction of nitrogen composition. The electronic properties are dominated by grain boundary scattering and electron transport across boundary barriers through thermal activation at band edge states at high temperatures. The conductivity below 130 K exhibits a weak temperature dependence, which is a signature of variable-range hopping conduction between localized states introduced by nitrogen incorporation.

  14. Single-component molecular conductor [Cu(dmdt)2] with three-dimensionally arranged magnetic moments exhibiting a coupled electric and magnetic transition.

    Science.gov (United States)

    Zhou, Biao; Idobata, Yuki; Kobayashi, Akiko; Cui, HengBo; Kato, Reizo; Takagi, Rina; Miyagawa, Kazuya; Kanoda, Kazushi; Kobayashi, Hayao

    2012-08-01

    Crystals of the single-component molecular conductor [Cu(dmdt)(2)] (dmdt = dimethyltetrathiafulvalenedithiolate) were prepared as a molecular system, with three-dimensionally arranged magnetic moments embedded in "sea" of π conduction electrons. [Cu(dmdt)(2)] had fairly large room-temperature conductivity (110 S cm(-1)) and exhibited weakly metallic behavior near room temperature. Below 265 K, the resistivity (R) increased very slowly with decreasing temperature and then increased rapidly, indicating a transition from a highly conducting state to an insulating state near 95 K. The magnetic susceptibility showed Curie-Weiss behavior at 100-300 K (C = 0.375 emu/mol, Θ = 180 K). The Curie constant and the high-temperature resistivity behavior indicate that conduction electrons and three-dimensionally arranged magnetic moments coexist in the crystal. The ESR intensity increased down to about 95 K. The ESR signal was broadened and decreased abruptly near 95 K, suggesting that electric and antiferromagnetic transitions occurred simultaneously near 95 K. The crystal structure was determined down to 13 K. To examine the stability of the twisted conformation of Cu complex with dithiolate ligands, the dihedral angle dependence of the conformational energy of an isolated M(L)(2)(n-) molecule was calculated, which revealed the dihedral angle dependence on the ligand (L) and the oxidation state of the molecule (n). High-pressure four-probe resistivity measurements were performed at 3.3-9.3 GPa using a diamond anvil cell. The small resistivity increase observed at 3.3 GPa below 60 K suggested that the insulating transition observed at ambient pressure near 95 K was essentially suppressed at 3.3 GPa. The intermolecular magnetic interactions were examined on the basis of simple mean field theory of antiferromagnetic transition and the calculated intermolecular overlap integrals of the singly occupied molecular orbital (SOMO) of Cu(dmdt)(2).

  15. Oscillator strength, transition rates and lifetimes for n=3 states in Al-like ions

    CERN Document Server

    Safronova, U I; Safronova, M S; Sataka, M

    2002-01-01

    Transition rates, oscillator strengths, and line strengths are calculated for the 3220 possible electric-dipole (E1) transitions between the 73 even-parity 3s3p sup 2 , 3s sup 2 3d, 3p sup 2 3d, 3d sup 2 3s and 3d sup 3 states and the 75 odd-parity 3s sup 2 3p, 3p sup 3 , 3s3p3d, and 3d sup 2 3p states in Al-like ions with the nuclear charges ranging from Z=15 to 100. Relativistic many-body perturbation theory (MBPT), including the Breit interaction, is used to evaluate retarded E1 matrix elements in length and velocity forms. The calculations start from a 1s sup 2 2s sup 2 2p sup 6 Dirac-Fock potential. First-order MBPT is used to obtain intermediate coupling coefficients and second-order MBPT is used to calculate transition matrix elements. Contributions from negative-energy states are included in the second order E1 matrix elements to ensure gauge-independence of transition amplitudes. The transition energies used in the calculation of oscillator strengths and transition rates are from second-order MBPT. T...

  16. State safety oversight program : audit of the tri-state oversight committee and the Washington metropolitan area transit authority, final audit report, March 4, 2010.

    Science.gov (United States)

    2010-03-04

    The Federal Transit Administration (FTA) conducted an on-site audit of the safety program implemented by the Washington Metropolitan Area Transit Authority (WMATA) and overseen by the Tri-State Oversight Committee (TOC) between December 14 and 17, 20...

  17. Real-time tRNA transit on single translating ribosomes at codon resolution

    Science.gov (United States)

    Uemura, Sotaro; Aitken, Colin Echeverría; Korlach, Jonas; Flusberg, Benjamin A.; Turner, Stephen W.; Puglisi, Joseph D.

    2015-01-01

    Translation by the ribosome occurs by a complex mechanism involving the coordinated interaction of multiple nucleic acid and protein ligands. Here we have used zero-mode waveguides (ZMWs) and sophisticated detection instrumentation to allow real-time observation of translation at physiologically-relevant (μM) ligand concentrations. Translation at each codon is monitored by stable binding of tRNAs – labeled with distinct fluorophores – to translating ribosomes, allowing direct detection of the identity of tRNA molecules bound to the ribosome, and therefore, the underlying mRNA sequence. We observe the transit of tRNAs on single translating ribosomes and have determined the number of tRNA molecules simultaneously bound to the ribosome, at each codon of an mRNA. Our results show that ribosomes are only briefly occupied by two tRNAs and that release of deacylated tRNA from the E site is uncoupled from binding of A-site tRNA and occurs rapidly after translocation. The methods outlined here have broad application to the study of mRNA sequences, and the mechanism and regulation of translation. PMID:20393556

  18. Strong-field effects in Rabi oscillations between a single state and a superposition of states

    International Nuclear Information System (INIS)

    Zhdanovich, S.; Milner, V.; Hepburn, J. W.

    2011-01-01

    Rabi oscillations of quantum population are known to occur in two-level systems driven by spectrally narrow laser fields. In this work we study Rabi oscillations induced by shaped broadband femtosecond laser pulses. Due to the broad spectral width of the driving field, the oscillations are initiated between a ground state and a coherent superposition of excited states, or a ''wave packet,'' rather than a single excited state. Our experiments reveal an intricate dependence of the wave-packet phase on the intensity of the laser field. We confirm numerically that the effect is associated with the strong-field nature of the interaction and provide a qualitative picture by invoking a simple theoretical model.

  19. Effect of non-stationary accretion on spectral state transitions: An example of a persistent neutron star LMXB 4U1636–536

    Science.gov (United States)

    Zhang, Hui; Yu, Wen-Fei

    2018-03-01

    Observations of black hole and neutron star X-ray binaries show that the luminosity of the hard-to-soft state transition is usually higher than that of the soft-to-hard state transition, indicating additional parameters other than mass accretion rate are required to interpret spectral state transitions. It has been found in some individual black hole or neutron star soft X-ray transients that the luminosity corresponding to the hard-to-soft state transition is positively correlated with the peak luminosity of the following soft state. In this work, we report the discovery of the same correlation in the single persistent neutron star low mass X-ray binary (LMXB) 4U 1636–536 based on data from the All Sky Monitor (ASM) on board RXTE, the Gas Slit Camera (GSC) on board MAXI and the Burst Alert Telescope (BAT) on board Swift. We also found such a positive correlation holds in this persistent neutron star LMXB in a luminosity range spanning about a factor of four. Our results indicate that non-stationary accretion also plays an important role in driving X-ray spectral state transitions in persistent accreting systems with small accretion flares, which is much less dramatic compared with the bright outbursts seen in many Galactic LMXB transients.

  20. The effect of the single-spin defect on the stability of the in-plane vortex state in 2D magnetic nanodots

    International Nuclear Information System (INIS)

    Mamica, S.; Lévy, J.-C. S.; Depondt, Ph.; Krawczyk, M.

    2011-01-01

    The aim of this study is to analyse the stability of the single in-plane vortex state in two-dimensional magnetic nanodots with a nonmagnetic impurity (single-spin defect) at the centre. Small square and circular dots including up to a few thousand of spins are studied by means of a microscopic theory with nearest-neighbour exchange interactions and dipolar interactions fully taken into account. We calculate the spin-wave frequencies versus the dipolar-to-exchange interaction ratio d to find the values of d for which the assumed state is stable. Transitions to other states and their dependence on d and the vortex size are investigated as well, with two types of transition found: vortex core formation for small d values (strong exchange interactions), and in-plane reorientation of spins for large d values (strong dipolar interactions). Various types of localized spin waves responsible for these transitions are identified.

  1. The first observation of EO transitions from negative parity states in even-even nucleus 160Dy

    International Nuclear Information System (INIS)

    Grigoriev, E.P.

    1988-01-01

    In even-even deformed nuclei up to now EO-transitions were found only between the states of the same spin belonging to Κ π = O + rotational bands. There is no forbidenness for EO-transitions between states belonging to bands with any other quantum number Κ provided both initial and final states have the same J π Κ values. EO-transitions may depopulate odd-parity states. In odd nuclei β-vibrational states are identified by transition with EO-components. Here transitions also proceed between states with the same J π K numbers. Even-even nuclide 160 Dy is the first nucleus where the EO-transitions between odd-parity states have been found

  2. Role of single-point mutations and deletions on transition temperatures in ideal proteinogenic heteropolymer chains in the gas phase.

    Science.gov (United States)

    Olivares-Quiroz, L

    2016-07-01

    A coarse-grained statistical mechanics-based model for ideal heteropolymer proteinogenic chains of non-interacting residues is presented in terms of the size K of the chain and the set of helical propensities [Formula: see text] associated with each residue j along the chain. For this model, we provide an algorithm to compute the degeneracy tensor [Formula: see text] associated with energy level [Formula: see text] where [Formula: see text] is the number of residues with a native contact in a given conformation. From these results, we calculate the equilibrium partition function [Formula: see text] and characteristic temperature [Formula: see text] at which a transition from a low to a high entropy states is observed. The formalism is applied to analyze the effect on characteristic temperatures [Formula: see text] of single-point mutations and deletions of specific amino acids [Formula: see text] along the chain. Two probe systems are considered. First, we address the case of a random heteropolymer of size K and given helical propensities [Formula: see text] on a conformational phase space. Second, we focus our attention to a particular set of neuropentapeptides, [Met-5] and [Leu-5] enkephalins whose thermodynamic stability is a key feature on their coupling to [Formula: see text] and [Formula: see text] receptors and the triggering of biochemical responses.

  3. Dynamical control of the spin transition inside the thermal hysteresis loop of a spin-crossover single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Boukheddaden, Kamel, E-mail: kbo@physique.uvsq.fr [GEMaC, Université de Versailles St-Quentin, 45 Avenue des Etats Unis, 78035 Versailles (France); Sy, Mouhamadou; Paez-Espejo, Miguel [GEMaC, Université de Versailles St-Quentin, 45 Avenue des Etats Unis, 78035 Versailles (France); Slimani, Ahmed [Laboratoire des matériaux ferroélectriques, Département de Physique, Faculté des Sciences de Sfax, Route de la Soukra km 3.5 BP 1171, 3018 Sfax (Tunisia); Varret, François [GEMaC, Université de Versailles St-Quentin, 45 Avenue des Etats Unis, 78035 Versailles (France)

    2016-04-01

    We have succeeded to achieve experimentally, using an adapted optical microscopy setup, the reversible control of the front transformation between the low-spin (LS)–high-spin (HS) interface in the spin-crossover (SC) single crystal [{Fe(NCSe)(py)_2}{sub 2}(m-bpypz)] undergoing a first-order transition at 112 K with a 7 K hysteresis width. For that, we first generate a phase separation state (a HS/LS interface at equilibrium) inside the hysteresis loop by tuning the light intensity of the microscope. In the second step, this intensity is monitored in such a way to drive, through a photo-heating process, the interface motion. This photo-control is found to be reversible, accurate and requiring a very small amount of energy. In addition the integrity of the crystal is maintained even after a large number of cycling. The experimental observations, are well described as a reaction diffusion process accounting for the front propagation and the photo-heating effects.

  4. Transition state for the NSD2-catalyzed methylation of histone H3 lysine 36.

    Science.gov (United States)

    Poulin, Myles B; Schneck, Jessica L; Matico, Rosalie E; McDevitt, Patrick J; Huddleston, Michael J; Hou, Wangfang; Johnson, Neil W; Thrall, Sara H; Meek, Thomas D; Schramm, Vern L

    2016-02-02

    Nuclear receptor SET domain containing protein 2 (NSD2) catalyzes the methylation of histone H3 lysine 36 (H3K36). It is a determinant in Wolf-Hirschhorn syndrome and is overexpressed in human multiple myeloma. Despite the relevance of NSD2 to cancer, there are no potent, selective inhibitors of this enzyme reported. Here, a combination of kinetic isotope effect measurements and quantum chemical modeling was used to provide subangstrom details of the transition state structure for NSD2 enzymatic activity. Kinetic isotope effects were measured for the methylation of isolated HeLa cell nucleosomes by NSD2. NSD2 preferentially catalyzes the dimethylation of H3K36 along with a reduced preference for H3K36 monomethylation. Primary Me-(14)C and (36)S and secondary Me-(3)H3, Me-(2)H3, 5'-(14)C, and 5'-(3)H2 kinetic isotope effects were measured for the methylation of H3K36 using specifically labeled S-adenosyl-l-methionine. The intrinsic kinetic isotope effects were used as boundary constraints for quantum mechanical calculations for the NSD2 transition state. The experimental and calculated kinetic isotope effects are consistent with an SN2 chemical mechanism with methyl transfer as the first irreversible chemical step in the reaction mechanism. The transition state is a late, asymmetric nucleophilic displacement with bond separation from the leaving group at (2.53 Å) and bond making to the attacking nucleophile (2.10 Å) advanced at the transition state. The transition state structure can be represented in a molecular electrostatic potential map to guide the design of inhibitors that mimic the transition state geometry and charge.

  5. Detailed Investigation of the Structural, Thermal, and Electronic Properties of Gold Isocyanide Complexes with Mechano-Triggered Single-Crystal-to-Single-Crystal Phase Transitions.

    Science.gov (United States)

    Seki, Tomohiro; Sakurada, Kenta; Muromoto, Mai; Seki, Shu; Ito, Hajime

    2016-02-01

    Mechano-induced phase transitions in organic crystalline materials, which can alter their properties, have received much attention. However, most mechano-responsive molecular crystals exhibit crystal-to-amorphous phase transitions, and the intermolecular interaction patterns in the daughter phase are difficult to characterize. We have investigated phenyl(phenylisocyanide)gold(I) (1) and phenyl(3,5-dimethylphenylisocyanide)gold(I) (2) complexes, which exhibit a mechano-triggered single-crystal-to-single-crystal phase transition. Previous reports of complexes 1 and 2 have focused on the relationships between the crystalline structures and photoluminescence properties; in this work we have focused on other aspects. The face index measurements of complexes 1 and 2 before and after the mechano-induced phase transitions have indicated that they undergo non-epitaxial phase transitions without a rigorous orientational relationship between the mother and daughter phases. Differential scanning calorimetry analyses revealed the phase transition of complex 1 to be enthalpically driven by the formation of new aurophilic interactions. In contrast, the phase transition of complex 2 was found to be entropically driven, with the closure of an empty void in the mother phase. Scanning electron microscopy observation showed that the degree of the charging effect of both complexes 1 and 2 was changed by the phase transitions, which suggests that the formation of the aurophilic interactions affords more effective conductive pathways. Moreover, flash-photolysis time-resolved microwave conductivity measurements revealed that complex 1 increased in conductivity after the phase change, whereas the conductivity of complex 2 decreased. These contrasting results were explained by the different patterns in the aurophilic interactions. Finally, an intriguing disappearing polymorphism of complex 2 has been reported, in which a polymorph form could not be obtained again after some period of time

  6. Single-Molecule Analysis of Protein Large-Amplitude Conformational Transitions

    Science.gov (United States)

    Yang, Haw

    2011-03-01

    Proteins have evolved to harness thermal fluctuations, rather than frustrated by them, to carry out chemical transformations and mechanical work. What are, then, the operation and design principles of protein machines? To frame the problem in a tractable way, several basic questions have been formulated to guide the experimental design: (a) How many conformational states can a protein sample on the functionally important timescale? (b) What are the inter-conversion rates between states? (c) How do ligand binding or interactions with other proteins modulate the motions? (d) What are the structural basis of flexibility and its underlying molecular mechanics? Guided by this framework, we have studied protein tyrosine phosphatase B, PtpB, from M. tuberculosis (a virulence factor of tuberculosis and a potential drug target) and adenylate kinase, AK, from E. coli (a ubiquitous energy-balancing enzyme in cells). These domain movements have been followed in real time on their respective catalytic timescales using high-resolution single-molecule Förster resonance energy transfer (FRET) spectroscopy. It is shown quantitatively that both PtpB and AK are capable of dynamically sampling two distinct states that correlate well with those observed by x-ray crystallography. Integrating these microscopic dynamics into macroscopic kinetics allows us to place the experimentally measured free-energy landscape in the context of enzymatic turnovers.

  7. Steady-state entanglement of harmonic oscillators via dissipation in a single superconducting artificial atom

    Science.gov (United States)

    Wang, Fei; Nie, Wei; Feng, Xunli; Oh, C. H.

    2016-07-01

    The correlated emission lasing (CEL) is experimentally demonstrated in harmonic oscillators coupled via a single three-level artificial atom [Phys. Rev. Lett. 115, 223603 (2015), 10.1103/PhysRevLett.115.223603] in which two-mode entanglement only exists in a certain time period when the harmonic oscillators are resonant with the atomic transitions. Here we examine this system and show that it is possible to obtain the steady-state entanglement when the two harmonic oscillators are resonant with Rabi sidebands. Applying dressed atomic states and Bogoliubov-mode transformation, we obtain the analytical results of the variance sum of a pair of Einstein-Podolsky-Rosen (EPR)-like operators. The stable entanglement originates from the dissipation process of the Bogoliubov modes because the atomic system can act as a reservoir in dressed state representation. We also show that the entanglement is robust against the dephasing rates of the superconducing atom, which is expected to have important applications in quantum information processing.

  8. Potential of Transition Metal Atoms Embedded in Buckled Monolayer g-C3N4 as Single-Atom Catalysts

    KAUST Repository

    Li, Shu-Long

    2017-10-27

    We use first-principles calculations to systematically explore the potential of transition metal atoms (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Ru, Rh, Pd, Ag, Ir, Pt, and Au) embedded in buckled monolayer g-C3N4 as single-atom catalysts. We show that clustering of Sc and Ti on g-C3N4 is thermodynamically impeded and that V, Cr, Mn, and Cu are much less susceptible to clustering than the other TM atoms under investigation. Strong bonding of the transition metal atoms in the cavities of g-C3N4 and high diffusion barriers together are responsible for single-atom fixation. Analysis of the CO oxidation process indicates that embedding of Cr and Mn in g-C3N4 gives rise to promising single-atom catalysts at low temperature.

  9. Kinetic Analysis for Macrocyclizations Involving Anionic Template at the Transition State

    Directory of Open Access Journals (Sweden)

    Vicente Martí-Centelles

    2012-01-01

    competitive oligomerization/polymerization processes yielding undesired oligomeric/polymeric byproducts. The effect of anions has also been included in the kinetic models, as they can act as catalytic templates in the transition state reducing and stabilizing the transition state. The corresponding differential equation systems for each kinetic model can be solved numerically. Through a comprehensive analysis of these results, it is possible to obtain a better understanding of the different parameters that are involved in the macrocyclization reaction mechanism and to develop strategies for the optimization of the desired processes.

  10. A Semi-Continuous State-Transition Probability HMM-Based Voice Activity Detector

    Directory of Open Access Journals (Sweden)

    H. Othman

    2007-02-01

    Full Text Available We introduce an efficient hidden Markov model-based voice activity detection (VAD algorithm with time-variant state-transition probabilities in the underlying Markov chain. The transition probabilities vary in an exponential charge/discharge scheme and are softly merged with state conditional likelihood into a final VAD decision. Working in the domain of ITU-T G.729 parameters, with no additional cost for feature extraction, the proposed algorithm significantly outperforms G.729 Annex B VAD while providing a balanced tradeoff between clipping and false detection errors. The performance compares very favorably with the adaptive multirate VAD, option 2 (AMR2.

  11. Evidence of departure from transition-state statistical model in different mass regions

    International Nuclear Information System (INIS)

    Das, P.; Ray, A.; Bhattacharya, C.; Mullick, K.; Bhattacharjee, T.; Banerjee, S.R.; Basu, D.N.; Bhattacharya, S.

    2000-01-01

    The emission of complex fragments from compound nucleus can be understood very well using transition-state method calculations, that have shown that for a large number of excitation functions of compound nuclei near A = 100, the reduced decay rates after the removal of phase space dependence are identical for all fragments, thus implying statistical emission. One can consider two scenarios for departure from statistical transition-state model. An experiment was performed to look for orbiting effect in 16 O+ 93 Nb reaction

  12. Optical nonlinearities of excitonic states in atomically thin 2D transition metal dichalcogenides

    Energy Technology Data Exchange (ETDEWEB)

    Soh, Daniel Beom Soo [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Proliferation Signatures Discovery and Exploitation Department

    2017-08-01

    We calculated the optical nonlinearities of the atomically thin monolayer transition metal dichalcogenide material (particularly MoS2), particularly for those linear and nonlinear transition processes that utilize the bound exciton states. We adopted the bound and the unbound exciton states as the basis for the Hilbert space, and derived all the dynamical density matrices that provides the induced current density, from which the nonlinear susceptibilities can be drawn order-by-order via perturbative calculations. We provide the nonlinear susceptibilities for the linear, the second-harmonic, the third-harmonic, and the kerr-type two-photon processes.

  13. A Semi-Continuous State-Transition Probability HMM-Based Voice Activity Detector

    Directory of Open Access Journals (Sweden)

    Othman H

    2007-01-01

    Full Text Available We introduce an efficient hidden Markov model-based voice activity detection (VAD algorithm with time-variant state-transition probabilities in the underlying Markov chain. The transition probabilities vary in an exponential charge/discharge scheme and are softly merged with state conditional likelihood into a final VAD decision. Working in the domain of ITU-T G.729 parameters, with no additional cost for feature extraction, the proposed algorithm significantly outperforms G.729 Annex B VAD while providing a balanced tradeoff between clipping and false detection errors. The performance compares very favorably with the adaptive multirate VAD, option 2 (AMR2.

  14. Thermally activated state transition technique for femto-Newton-level force measurement.

    Science.gov (United States)

    Chen, Feng-Jung; Wong, Jhih-Sian; Hsu, Ken Y; Hsu, Long

    2012-05-01

    We develop and test a thermally activated state transition technique for ultraweak force measurement. As a force sensor, the technique was demonstrated on a classical Brownian bead immersed in water and restrained by a bistable optical trap. A femto-Newton-level flow force imposed on this sensor was measured by monitoring changes in the transition rates of the bead hopping between two energy states. The treatment of thermal disturbances as a requirement instead of a limiting factor is the major feature of the technique, and provides a new strategy by which to measure other ultraweak forces beyond the thermal noise limit.

  15. Analysis of Tax Revenues to the State Budget of Economies in Transition Countries

    Directory of Open Access Journals (Sweden)

    Julia V. Koval

    2013-01-01

    Full Text Available The article, using statistical data, analyzes tax revenues to the state budget of the economies in transition countries, namely Russia, Georgia, Ukraine and the Czech Republic. Such analysis is necessary to identify the main ways to pump up the budget and, using comparative analysis, to draw conclusions about the methods, applied by economies in transition countries to come out of the crisis and restore the economy. The main reasons of tax revenues increase or decrease as the main source of pumping up the state budget are examined. Methods of taxation policy, the countries used for the economy restoration are described.

  16. Single-Crystal-to-Single-Crystal Transition in an Enantiopure [7]Helquat Salt: The First Observation of a Reversible Phase Transition in a Helicene-Like Compound

    Czech Academy of Sciences Publication Activity Database

    Nath, N. K.; Severa, Lukáš; Kunetskiy, Roman Alexejevič; Císařová, I.; Fulem, M.; Růžička, K.; Koval, Dušan; Kašička, Václav; Teplý, Filip; Naumov, P.

    2015-01-01

    Roč. 21, č. 39 (2015), s. 13508-13512 ISSN 0947-6539 R&D Projects: GA ČR GA13-19213S; GA ČR GA13-32974S; GA ČR(CZ) GA13-17224S Grant - others:GA AV ČR(CZ) M200551208 Institutional support: RVO:61388963 Keywords : chirality * helicene * phase transitions * polymorphism * X-ray diffraction Subject RIV: CC - Organic Chemistry Impact factor: 5.771, year: 2015

  17. Most spin-1/2 transition-metal ions do have single ion anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jia; Whangbo, Myung-Hwan, E-mail: hxiang@fudan.edu.cn, E-mail: mike-whangbo@ncsu.edu [Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695 (United States); Koo, Hyun-Joo [Department of Chemistry and Research Institute for Basic Sciences, Kyung Hee University, Seoul 130-701 (Korea, Republic of); Xiang, Hongjun, E-mail: hxiang@fudan.edu.cn, E-mail: mike-whangbo@ncsu.edu [Key Laboratory of Computational Physical Sciences (Ministry of Education), State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200433 (China); Kremer, Reinhard K. [Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart (Germany)

    2014-09-28

    The cause for the preferred spin orientation in magnetic systems containing spin-1/2 transition-metal ions was explored by studying the origin of the easy-plane anisotropy of the spin-1/2 Cu{sup 2+} ions in CuCl{sub 2}·2H{sub 2}O, LiCuVO{sub 4}, CuCl{sub 2}, and CuBr{sub 2} on the basis of density functional theory and magnetic dipole-dipole energy calculations as well as a perturbation theory treatment of the spin-orbit coupling. We find that the spin orientation observed for these spin-1/2 ions is not caused by their anisotropic spin exchange interactions, nor by their magnetic dipole-dipole interactions, but by the spin-orbit coupling associated with their crystal-field split d-states. Our study also predicts in-plane anisotropy for the Cu{sup 2+} ions of Bi{sub 2}CuO{sub 4} and Li{sub 2}CuO{sub 2}. The results of our investigations dispel the mistaken belief that magnetic systems with spin-1/2 ions have no magnetic anisotropy induced by spin-orbit coupling.

  18. State-Transition-Aware Spilling Heuristic for MLC STT-RAM-Based Registers

    Directory of Open Access Journals (Sweden)

    Yuanhui Ni

    2017-01-01

    Full Text Available Multilevel Cell Spin-Transfer Torque Random Access Memory (MLC STT-RAM is a promising nonvolatile memory technology to build registers for its natural immunity to electromagnetic radiation in rad-hard space environment. Unlike traditional SRAM-based registers, MLC STT-RAM exhibits unbalanced write state transitions due to the fact that the magnetization directions of hard and soft domains cannot be flipped independently. This feature leads to nonuniform costs of write states in terms of latency and energy. However, current SRAM-targeting register allocations do not have a clear understanding of the impact of the different write state-transition costs. As a result, those approaches heuristically select variables to be spilled without considering the spilling priority imposed by MLC STT-RAM. Aiming to address this limitation, this paper proposes a state-transition-aware spilling cost minimization (SSCM policy, to save power when MLC STT-RAM is employed in register design. Specifically, the spilling cost model is first constructed according to the linear combination of different state-transition frequencies. Directed by the proposed cost model, the compiler picks up spilling candidates to achieve lower power and higher performance. Experimental results show that the proposed SSCM technique can save energy by 19.4% and improve the lifetime by 23.2% of MLC STT-RAM-based register design.

  19. Glass transition of PCBM, P3HT and their blends in quenched state

    International Nuclear Information System (INIS)

    Ngo, Trinh Tung; Nguyen, Duc Nghia; Nguyen, Van Tuyen

    2012-01-01

    In this work the thermal behavior with the glass transition of phenyl-C 61 -butyric acid methyl ester (PCBM), poly(3-hexylthiophene) (P3HT) and their blends was investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Both TGA and DSC measurements show that PCBM contains around 1% residual solvent in the crystalline structure. The glass transition of PCBM, P3HT and their blends was determined by quenching techniques. The quenched state of the materials has a strong effect on the glass transition of the materials, especially in the case of PCBM. In all blend compositions only one glass transition temperature was found. These results indicate that PCBM and P3HT are thermodynamically miscible in all blend compositions. (paper)

  20. Columbus State University Global Observation and Outreach for the 2012 Transit of Venus

    Science.gov (United States)

    Perry, Matthew; McCarty, C.; Bartow, M.; Hood, J. C.; Lodder, K.; Johnson, M.; Cruzen, S. T.; Williams, R. N.

    2013-01-01

    Faculty, staff and students from Columbus State University’s (CSU’s) Coca-Cola Space Science Center presented a webcast of the 2012 Transit of Venus from three continents to a global audience of 1.4 million unique viewers. Team members imaged the transit with telescopes using white-light, hydrogen-alpha, and calcium filters, from Alice Springs, Australia; the Gobi Desert, Mongolia; Bryce Canyon, UT; and Columbus, GA. Images were webcast live during the transit in partnership with NASA’s Sun-Earth Day program, and Science Center staff members were featured on NASA TV. Local members of the public were brought in for a series of outreach initiatives, in both Georgia and Australia, before and during the transit. The data recorded from the various locations have been archived for use in demonstrating principles such as the historical measurement of the astronomical unit.

  1. The glass transition and enthalpy recovery of a single polystyrene ultrathin film using Flash DSC.

    Science.gov (United States)

    Koh, Yung P; Simon, Sindee L

    2017-05-28

    The kinetics of the glass transition are measured for a single polystyrene ultrathin film of 20 nm thickness using Flash differential scanning calorimetry (DSC). T g is measured over a range of cooling rates from 0.1 to 1000 K/s and is depressed compared to the bulk. The depression decreases with increasing cooling rate, from 12 K lower than the bulk at 0.1 K/s to no significant change at 1000 K/s. Isothermal enthalpy recovery measurements are performed from 50 to 115 °C, and from these experiments, the temperature dependence of the induction time along the glass line is obtained, as well as the temperature dependence of the time scale required to reach equilibrium, providing a measure of the shortest effective glassy relaxation time and the longest effective equilibrium relaxation time, respectively. The induction time for the ultrathin film is found to be similar to the bulk at all temperatures presumably because the T g values are the same due to the use of a cooling rate of 1000 K/s prior to the enthalpy recovery measurements. On the other hand, the times required to reach equilibrium for the ultrathin film and bulk are similar at 100 °C, and considerably shorter for the ultrathin film at 90 °C, consistent with faster dynamics under nanoconfinement at low temperatures. The magnitude of the "T g depression" is smaller when using the equilibrium relaxation time from the structural recovery experiment as a measure of the dynamics than when measuring T g after a cooling experiment. A relaxation map is developed to summarize the results.

  2. The glass transition and enthalpy recovery of a single polystyrene ultrathin film using Flash DSC

    Science.gov (United States)

    Koh, Yung P.; Simon, Sindee L.

    2017-05-01

    The kinetics of the glass transition are measured for a single polystyrene ultrathin film of 20 nm thickness using Flash differential scanning calorimetry (DSC). Tg is measured over a range of cooling rates from 0.1 to 1000 K/s and is depressed compared to the bulk. The depression decreases with increasing cooling rate, from 12 K lower than the bulk at 0.1 K/s to no significant change at 1000 K/s. Isothermal enthalpy recovery measurements are performed from 50 to 115 °C, and from these experiments, the temperature dependence of the induction time along the glass line is obtained, as well as the temperature dependence of the time scale required to reach equilibrium, providing a measure of the shortest effective glassy relaxation time and the longest effective equilibrium relaxation time, respectively. The induction time for the ultrathin film is found to be similar to the bulk at all temperatures presumably because the Tg values are the same due to the use of a cooling rate of 1000 K/s prior to the enthalpy recovery measurements. On the other hand, the times required to reach equilibrium for the ultrathin film and bulk are similar at 100 °C, and considerably shorter for the ultrathin film at 90 °C, consistent with faster dynamics under nanoconfinement at low temperatures. The magnitude of the "Tg depression" is smaller when using the equilibrium relaxation time from the structural recovery experiment as a measure of the dynamics than when measuring Tg after a cooling experiment. A relaxation map is developed to summarize the results.

  3. WASP-36b: A NEW TRANSITING PLANET AROUND A METAL-POOR G-DWARF, AND AN INVESTIGATION INTO ANALYSES BASED ON A SINGLE TRANSIT LIGHT CURVE

    Energy Technology Data Exchange (ETDEWEB)

    Smith, A. M. S.; Anderson, D. R.; Hellier, C.; Maxted, P. F. L.; Smalley, B.; Southworth, J. [Astrophysics Group, Keele University, Staffordshire, ST5 5BG (United Kingdom); Collier Cameron, A. [SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, Fife, KY16 9SS (United Kingdom); Gillon, M.; Jehin, E. [Institut d' Astrophysique et de Geophysique, Universite de Liege, Allee du 6 Aout, 17 Bat. B5C, Liege 1 (Belgium); Lendl, M.; Queloz, D.; Triaud, A. H. M. J.; Pepe, F.; Segransan, D.; Udry, S. [Observatoire de Geneve, Universite de Geneve, 51 Chemin des Maillettes, 1290 Sauverny (Switzerland); West, R. G. [Department of Physics and Astronomy, University of Leicester, Leicester, LE1 7RH (United Kingdom); Barros, S. C. C.; Pollacco, D. [Astrophysics Research Centre, School of Mathematics and Physics, Queen' s University, University Road, Belfast, BT7 1NN (United Kingdom); Street, R. A., E-mail: amss@astro.keele.ac.uk [Las Cumbres Observatory, 6740 Cortona Drive Suite 102, Goleta, CA 93117 (United States)

    2012-04-15

    We report the discovery, from WASP and CORALIE, of a transiting exoplanet in a 1.54 day orbit. The host star, WASP-36, is a magnitude V = 12.7, metal-poor G2 dwarf (T{sub eff} = 5959 {+-} 134 K), with [Fe/H] =-0.26 {+-} 0.10. We determine the planet to have mass and radius, respectively, 2.30 {+-} 0.07 and 1.28 {+-} 0.03 times that of Jupiter. We have eight partial or complete transit light curves, from four different observatories, which allow us to investigate the potential effects on the fitted system parameters of using only a single light curve. We find that the solutions obtained by analyzing each of these light curves independently are consistent with our global fit to all the data, despite the apparent presence of correlated noise in at least two of the light curves.

  4. 45 CFR 1321.41 - Single State planning and service area.

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 4 2010-10-01 2010-10-01 false Single State planning and service area. 1321.41 Section 1321.41 Public Welfare Regulations Relating to Public Welfare (Continued) OFFICE OF HUMAN... PROGRAMS GRANTS TO STATE AND COMMUNITY PROGRAMS ON AGING State Agency Responsibilities § 1321.41 Single...

  5. Turbulent states and their transitions in mathematical models for ventricular tissue: The effects of random interstitial fibroblasts

    Science.gov (United States)

    Nayak, Alok Ranjan; Pandit, Rahul

    2015-09-01

    We study the dynamical behaviors of two types of spiral- and scroll-wave turbulence states, respectively, in two-dimensional (2D) and three-dimensional (3D) mathematical models, of human, ventricular, myocyte cells that are attached to randomly distributed interstitial fibroblasts; these turbulence states are promoted by (a) the steep slope of the action-potential-duration-restitution (APDR) plot or (b) early afterdepolarizations (EADs). Our single-cell study shows that (1) the myocyte-fibroblast (MF) coupling Gj and (2) the number Nf of fibroblasts in an MF unit lower the steepness of the APDR slope and eliminate the EAD behaviors of myocytes; we explore the pacing dependence of such EAD suppression. In our 2D simulations, we observe that a spiral-turbulence (ST) state evolves into a state with a single, rotating spiral (RS) if either (a) Gj is large or (b) the maximum possible number of fibroblasts per myocyte Nfmax is large. We also observe that the minimum value of Gj, for the transition from the ST to the RS state, decreases as Nfmax increases. We find that, for the steep-APDR-induced ST state, once the MF coupling suppresses ST, the rotation period of a spiral in the RS state increases as (1) Gj increases, with fixed Nfmax, and (2) Nfmax increases, with fixed Gj. We obtain the boundary between ST and RS stability regions in the Nfmax-Gj plane. In particular, for low values of Nfmax, the value of Gj, at the ST-RS boundary, depends on the realization of the randomly distributed fibroblasts; this dependence decreases as Nfmax increases. Our 3D studies show a similar transition from scroll-wave turbulence to a single, rotating, scroll-wave state because of the MF coupling. We examine the experimental implications of our study and propose that the suppression (a) of the steep slope of the APDR or (b) EADs can eliminate spiral- and scroll-wave turbulence in heterogeneous cardiac tissue, which has randomly distributed fibroblasts.

  6. Specification, construction, and exact reduction of state transition system models of biochemical processes.

    Science.gov (United States)

    Bugenhagen, Scott M; Beard, Daniel A

    2012-10-21

    Biochemical reaction systems may be viewed as discrete event processes characterized by a number of states and state transitions. These systems may be modeled as state transition systems with transitions representing individual reaction events. Since they often involve a large number of interactions, it can be difficult to construct such a model for a system, and since the resulting state-level model can involve a huge number of states, model analysis can be difficult or impossible. Here, we describe methods for the high-level specification of a system using hypergraphs, for the automated generation of a state-level model from a high-level model, and for the exact reduction of a state-level model using information from the high-level model. Exact reduction is achieved through the automated application to the high-level model of the symmetry reduction technique and reduction by decomposition by independent subsystems, allowing potentially significant reductions without the need to generate a full model. The application of the method to biochemical reaction systems is illustrated by models describing a hypothetical ion-channel at several levels of complexity. The method allows for the reduction of the otherwise intractable example models to a manageable size.

  7. Phase transitions and Heisenberg limited metrology in an Ising chain interacting with a single-mode cavity field

    DEFF Research Database (Denmark)

    Gammelmark, Søren; Mølmer, Klaus

    2011-01-01

    to determine the complete phase diagram of the system. The analysis reveals both first- and second-order Dicke phase transitions into a super-radiant state, and the cavity mean field in this regime acts as an effective magnetic field, which restricts the Ising chain dynamics to parameter ranges away from......We investigate the thermodynamics of a combined Dicke and Ising model that exhibits a rich phenomenology arising from the second-order and quantum phase transitions from the respective models. The partition function is calculated using mean-field theory, and the free energy is analyzed in detail...... the Ising phase transition. Physical systems with first-order phase transitions are natural candidates for metrology and calibration purposes, and we apply filter theory to show that the sensitivity of the physical system to temperature and external fields reaches the 1/N Heisenberg limit....

  8. Facilitating a Major Staffing Transition in a State Psychiatric Hospital With Changes to Nursing Orientation.

    Science.gov (United States)

    Birnbaum, Shira; Sperber-Weiss, Doreen; Dimitrios, Timothy; Eckel, Donald; Monroy-Miller, Cherry; Monroe, Janet J; Friedman, Ross; Ologbosele, Mathias; Epo, Grace; Sharpe, Debra; Zarski, Yongsuk

    A large state psychiatric hospital experienced a state-mandated Reduction in Force that resulted in the abrupt loss and rapid turnover of more than 40% of its nursing and paraprofessional staff. The change exemplified current national trends toward downsizing and facility closure. This article describes revisions to the nursing orientation program that supported cost containment and fidelity to mission and clinical practices during the transition. An existing nursing orientation program was reconfigured in alignment with principles of rational instructional design and a core-competencies model of curriculum development, evidence-based practices that provided tactical clarity and commonality of purpose during a complex and emotionally charged transition period. Program redesign enabled efficiencies that facilitated the transition, with no evidence of associated negative effects. The process described here offers an example for hospitals facing similar workforce reorganization in an era of public sector downsizing.

  9. Signatures for shape-phase transitions in the rare-earth nuclei, in the evolution of single-particle spectra and two-particle transfer-intensities

    Energy Technology Data Exchange (ETDEWEB)

    Fossion, R. [Instituto de Ciencias Nucleares, UNAM, Apartado Postal 70-543, 04510 Mexico D. F. (Mexico)

    2008-12-15

    The rare-earth Nd, Sm, Gd and Dy nuclei are well known to undergo a shape-phase transition around N {approx} 90 from vibrational to rotational behaviour - or, correspondingly - from a spherical nuclear shape to an axial-symmetric deformed shape. This can experimentally be verified by, for example, the evolution of the R{sub 4/2} = E(4{sup +}{sub 1})/E(2{sup +}{sub 1}) ratio, or the evolution of the quadrupole moment, Q{sub 2}. Recently, the study o nuclear phase-shape transitions has gained considerable interest, since the introduction of exact algebraic solutions for the critical points many of the different phase-shape transitions that are possible in the atomic nucleus. In this contribution, in the first part, we investigate the microscopic underlying mechanism that drives the rare-earth isotopes towards deformation, studying the evolution of their proton an neutron single-particle spectra within the Relativistic Hartree-Bogoliubov model. In the second part, within the Interacting Boson Model and the framework with boson coherent states, and in the light of renewed interest in experiments on two-particle transfer-reactions, we study the evolution of the transfer spectroscopic intensities as a possible signature of shape-phase transitions. (Author)

  10. Unifying Exchange Sensitivity in Transition-Metal Spin-State Ordering and Catalysis through Bond Valence Metrics.

    Science.gov (United States)

    Gani, Terry Z H; Kulik, Heather J

    2017-11-14

    Accurate predictions of spin-state ordering, reaction energetics, and barrier heights are critical for the computational discovery of open-shell transition-metal (TM) catalysts. Semilocal approximations in density functional theory, such as the generalized gradient approximation (GGA), suffer from delocalization error that causes them to overstabilize strongly bonded states. Descriptions of energetics and bonding are often improved by introducing a fraction of exact exchange (e.g., erroneous low-spin GGA ground states are instead correctly predicted as high-spin with a hybrid functional). The degree of spin-splitting sensitivity to exchange can be understood based on the chemical composition of the complex, but the effect of exchange on reaction energetics within a single spin state is less well-established. Across a number of model iron complexes, we observe strong exchange sensitivities of reaction barriers and energies that are of the same magnitude as those for spin splitting energies. We rationalize trends in both reaction and spin energetics by introducing a measure of delocalization, the bond valence of the metal-ligand bonds in each complex. The bond valence thus represents a simple-to-compute property that unifies understanding of exchange sensitivity for catalytic properties and spin-state ordering in TM complexes. Close agreement of the resulting per-metal-organic-bond sensitivity estimates, together with failure of alternative descriptors demonstrates the utility of the bond valence as a robust descriptor of how differences in metal-ligand delocalization produce differing relative energetics with exchange tuning. Our unified description explains the overall effect of exact exchange tuning on the paradigmatic two-state FeO + /CH 4 reaction that combines challenges of spin-state and reactivity predictions. This new descriptor-sensitivity relationship provides a path to quantifying how predictions in transition-metal complex screening are sensitive to the

  11. State-and-transition simulation models: a framework for forecasting landscape change

    Science.gov (United States)

    Daniel, Colin; Frid, Leonardo; Sleeter, Benjamin M.; Fortin, Marie-Josée

    2016-01-01

    SummaryA wide range of spatially explicit simulation models have been developed to forecast landscape dynamics, including models for projecting changes in both vegetation and land use. While these models have generally been developed as separate applications, each with a separate purpose and audience, they share many common features.We present a general framework, called a state-and-transition simulation model (STSM), which captures a number of these common features, accompanied by a software product, called ST-Sim, to build and run such models. The STSM method divides a landscape into a set of discrete spatial units and simulates the discrete state of each cell forward as a discrete-time-inhomogeneous stochastic process. The method differs from a spatially interacting Markov chain in several important ways, including the ability to add discrete counters such as age and time-since-transition as state variables, to specify one-step transition rates as either probabilities or target areas, and to represent multiple types of transitions between pairs of states.We demonstrate the STSM method using a model of land-use/land-cover (LULC) change for the state of Hawai'i, USA. Processes represented in this example include expansion/contraction of agricultural lands, urbanization, wildfire, shrub encroachment into grassland and harvest of tree plantations; the model also projects shifts in moisture zones due to climate change. Key model output includes projections of the future spatial and temporal distribution of LULC classes and moisture zones across the landscape over the next 50 years.State-and-transition simulation models can be applied to a wide range of landscapes, including questions of both land-use change and vegetation dynamics. Because the method is inherently stochastic, it is well suited for characterizing uncertainty in model projections. When combined with the ST-Sim software, STSMs offer a simple yet powerful means for developing a wide range of models of

  12. Phase transitions in A 4 Li (HSO 4) 3 (SO 4); A= Rb, K: Single crystal ...

    Indian Academy of Sciences (India)

    Keywords. Phase transition; ferroelastic; cryo-crystallography; crystal structure. Abstract. The crystal structure of ferroelastic Rb4Li(HSO4)3(SO4) has been determined at two temperatures, which indicates a structural phase transition, tetragonal 43 with = 7.629(1) Å, = 29.497(2) Å at 293 K and monoclinic 21 with  ...

  13. Critical behaviour of continuous phase transitions with infinitely many absorbing states

    International Nuclear Information System (INIS)

    Hua Dayin; Wang Lieyan; Chen Ting

    2006-01-01

    A lattice gas model is proposed for the A 2 + 2B 2 → 2B 2 A reaction system with particle diffusion. In the model, A 2 dissociates in the random dimer-filling mechanism and B 2 dissociation is in the end-on dimer-filling mechanism. A reactive window appears and the system exhibits a continuous phase transition from a reactive state to a covered state with infinitely many absorbing states. When the diffusion of particle A and AB is included, there are still infinitely many absorbing states for the continuous phase transition, but it is found that the critical behaviour changes from the directed percolation (DP) class to the pair contact process with diffusion (PCPD) class

  14. "Predicting" Polymorphs of Pharmaceuticals Using Hydrogen Bond Propensities: Probenecid and Its Two Single-Crystal-to-Single-Crystal Phase Transitions.

    Science.gov (United States)

    Nauha, Elisa; Bernstein, Joel

    2015-06-01

    The recently developed hydrogen-bonding propensity tool in the Cambridge Structural Database software package (Mercury) was tested to predict polymorphs. The compounds for the study were chosen from a list of approximately 300 pharmaceutically important compounds, for which multiple crystal forms had not been previously reported. The hydrogen-bonding propensity analysis was carried out on approximately 60 randomly selected compounds from this list. Several compounds with a high probability for exhibiting polymorphism in the analysis were chosen for a limited experimental crystal form screening. One of the compounds, probenecid, did not yield polymorphs by traditional solution crystallization screening, but differential scanning calorimetry revealed three polymorphs. All of them exhibit the same hydrogen bonding and transform via two reversible single-crystal-to single-crystal transformations, which have been characterized in detail through three single-crystal structure determinations at appropriate temperatures. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

  15. The Multi-state Latent Factor Intensity Model for Credit Rating Transitions

    NARCIS (Netherlands)

    Koopman, S.J.; Lucas, A.; Monteiro, A.

    2008-01-01

    A new empirical reduced-form model for credit rating transitions is introduced. It is a parametric intensity-based duration model with multiple states and driven by exogenous covariates and latent dynamic factors. The model has a generalized semi-Markov structure designed to accommodate many of the

  16. Approaches to incorporating climate change effects in state and transition simulation models of vegetation

    Science.gov (United States)

    Becky K. Kerns; Miles A. Hemstrom; David Conklin; Gabriel I. Yospin; Bart Johnson; Dominique Bachelet; Scott Bridgham

    2012-01-01

    Understanding landscape vegetation dynamics often involves the use of scientifically-based modeling tools that are capable of testing alternative management scenarios given complex ecological, management, and social conditions. State-and-transition simulation model (STSM) frameworks and software such as PATH and VDDT are commonly used tools that simulate how landscapes...

  17. Forecasting timber, biomass, and tree carbon pools with the output of state and transition models

    Science.gov (United States)

    Xiaoping Zhou; Miles A. Hemstrom

    2012-01-01

    The Integrated Landscape Assessment Project (ILAP) uses spatial vegetation data and state and transition models (STM) to forecast future vegetation conditions and the interacting effects of natural disturbances and management activities. Results from ILAP will help land managers, planners, and policymakers evaluate management strategies that reduce fire risk, improve...

  18. Educational Transitions in the United States: Reflections on the American Dream

    Science.gov (United States)

    Crawford, Paul T.

    2012-01-01

    Education involves socialization so that individuals become productive members of society. At present, in the United States, educational transitions are primarily viewed in terms of their location in an outcomes-oriented process and framed as helping people achieve the American Dream, but in terms of the status quo national economic interest. But…

  19. Converting Chair-like Transition States into Zig-Zag Projections A ...

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 19; Issue 9. Converting Chair-like Transition States into Zig-Zag Projections: A Method of Drawing Stereochemical Structures. Syed R Hussaini. Classroom Volume 19 Issue 9 September 2014 pp 846-850 ...

  20. Converting Chair-like Transition States into Zig-Zag Projections A ...

    Indian Academy of Sciences (India)

    IAS Admin

    Department of Chemistry and. Biochemistry. The University of Tulsa 800. South Tucker Driver. Tulsa, OK 74104, USA. Email: syedhussaini@utulsa.edu. A short and easy method for the conversion of chair-like transition states into zig-zag projections using planar cyclohexane structures, and also the concepts of change of.

  1. Excitonic instability at the spin-state transition in the two-band Hubbard model

    Czech Academy of Sciences Publication Activity Database

    Kuneš, Jan; Augustinský, Pavel

    2014-01-01

    Roč. 89, č. 11 (2014), "115134-1"-"115134-8" ISSN 1098-0121 R&D Projects: GA ČR GA13-25251S Institutional support: RVO:68378271 Keywords : excitonic condensation * spin-state transition * dynamical mean-field theory Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.736, year: 2014

  2. Magnetic field effect on state energies and transition frequency of a ...

    Indian Academy of Sciences (India)

    polaron in an anisotropic quantum dot (AQD) under an applied magnetic field along the z-direction. The effects of the magnetic field and the electron–phonon coupling strength are taken into account. It is found that the ground and the first excited state energies and the transition frequency are increas- ing functions of the ...

  3. State-and-transition model archetypes: a global taxonomy of rangeland change

    Science.gov (United States)

    State and transition models (STMs) synthesize science-based and local knowledge to formally represent the dynamics of rangeland and other ecosystems. Mental models or concepts of ecosystem dynamics implicitly underlie all management decisions in rangelands and thus how people influence rangeland sus...

  4. Efficient Computation of Transition State Resonances and Reaction Rates from a Quantum Normal Form

    NARCIS (Netherlands)

    Schubert, Roman; Waalkens, Holger; Wiggins, Stephen

    2006-01-01

    A quantum version of a recent formulation of transition state theory in phase space is presented. The theory developed provides an algorithm to compute quantum reaction rates and the associated Gamov-Siegert resonances with very high accuracy. The algorithm is especially efficient for

  5. A Visualization System for Predicting Learning Activities Using State Transition Graphs

    Science.gov (United States)

    Okubo, Fumiya; Shimada, Atsushi; Taniguchi, Yuta

    2017-01-01

    In this paper, we present a system for visualizing learning logs of a course in progress together with predictions of learning activities of the following week and the final grades of students by state transition graphs. Data are collected from 236 students attending the course in progress and from 209 students attending the past course for…

  6. Czochralski method of growing single crystals. State-of-art

    International Nuclear Information System (INIS)

    Bukowski, A.; Zabierowski, P.

    1999-01-01

    Modern Czochralski method of single crystal growing has been described. The example of Czochralski process is given. The advantages that caused the rapid progress of the method have been presented. The method limitations that motivated the further research and new solutions are also presented. As the example two different ways of the technique development has been described: silicon single crystals growth in the magnetic field; continuous liquid feed of silicon crystals growth. (author)

  7. High transition frequencies of dynamic functional connectivity states in the creative brain.

    Science.gov (United States)

    Li, Junchao; Zhang, Delong; Liang, Aiying; Liang, Bishan; Wang, Zengjian; Cai, Yuxuan; Gao, Mengxia; Gao, Zhenni; Chang, Song; Jiao, Bingqing; Huang, Ruiwang; Liu, Ming

    2017-04-06

    Creativity is thought to require the flexible reconfiguration of multiple brain regions that interact in transient and complex communication patterns. In contrast to prior emphases on searching for specific regions or networks associated with creative performance, we focused on exploring the association between the reconfiguration of dynamic functional connectivity states and creative ability. We hypothesized that a high frequency of dynamic functional connectivity state transitions will be associated with creative ability. To test this hypothesis, we recruited a high-creative group (HCG) and a low-creative group (LCG) of participants and collected resting-state fMRI (R-fMRI) data and Torrance Tests of Creative Thinking (TTCT) scores from each participant. By combining an independent component analysis with a dynamic network analysis approach, we discovered the HCG had more frequent transitions between dynamic functional connectivity (dFC) states than the LCG. Moreover, a confirmatory analysis using multiplication of temporal derivatives also indicated that there were more frequent dFC state transitions in the HCG. Taken together, these results provided empirical evidence for a linkage between the flexible reconfiguration of dynamic functional connectivity states and creative ability. These findings have the potential to provide new insights into the neural basis of creativity.

  8. Grassland to shrubland state transitions enhance carbon sequestration in the northern Chihuahuan Desert.

    Science.gov (United States)

    Petrie, M D; Collins, S L; Swann, A M; Ford, P L; Litvak, M E

    2015-03-01

    The replacement of native C4 -dominated grassland by C3 -dominated shrubland is considered an ecological state transition where different ecological communities can exist under similar environmental conditions. These state transitions are occurring globally, and may be exacerbated by climate change. One consequence of the global increase in woody vegetation may be enhanced ecosystem carbon sequestration, although the responses of arid and semiarid ecosystems may be highly variable. During a drier than average period from 2007 to 2011 in the northern Chihuahuan Desert, we found established shrubland to sequester 49 g C m(-2) yr(-1) on average, while nearby native C4 grassland was a net source of 31 g C m(-2) yr(-1) over this same period. Differences in C exchange between these ecosystems were pronounced--grassland had similar productivity compared to shrubland but experienced higher C efflux via ecosystem respiration, while shrubland was a consistent C sink because of a longer growing season and lower ecosystem respiration. At daily timescales, rates of carbon exchange were more sensitive to soil moisture variation in grassland than shrubland, such that grassland had a net uptake of C when wet but lost C when dry. Thus, even under unfavorable, drier than average climate conditions, the state transition from grassland to shrubland resulted in a substantial increase in terrestrial C sequestration. These results illustrate the inherent tradeoffs in quantifying ecosystem services that result from ecological state transitions, such as shrub encroachment. In this case, the deleterious changes to ecosystem services often linked to grassland to shrubland state transitions may at least be partially offset by increased ecosystem carbon sequestration. © 2014 John Wiley & Sons Ltd.

  9. Fluorescence excitation involving multiple electron transition states of N{sub 2} and CO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Wu, C.Y.R.; Chen, F.Z.; Hung, T.; Judge, D.L. [Univ. of Southern California, Los Angeles, CA (United States)

    1997-04-01

    The electronic states and electronic structures of N{sub 2} and CO{sub 2} in the 8-50 eV energy region have been studied extensively both experimentally and theoretically. In the energy region higher than 25 eV there exists many electronic states including multiple electron transition (MET) states which are responsible for producing most of the dissociative photoionization products. The electronic states at energies higher than 50 eV have been mainly determined by Auger spectroscopy, double charge transfer, photofragment spectroscopy and ion-ion coincidence spectroscopy. The absorption and ionization spectra of these molecules at energies higher than 50 eV mainly show a monotonic decrease in cross section values and exhibit structureless features. The decay channels of MET and Rydberg (or superexcited) states include autoionization, ionization, dissociative ionization, predissociation, and dissociation while those of single ion and multiple ion states may involve predissociation. and dissociation processes. The study of fluorescence specifically probes electronically excited species resulting from the above-mentioned decay channels and provides information for understanding the competition among these channels.

  10. Marianne in the Home. Political Revolution and Demographic Transition in France and the United States {Population, 1, 2000)

    OpenAIRE

    R. Binion

    2001-01-01

    Binion Rudolph.- Marianne in the Home. Political Revolution and Demographic Transition in France and the United States Historians of France agree about the precocity of the French demographic transition while disagreeing about its causes and its possible links with the partly coterminous Revolution of 1789. They ignore the American transition which began at the time of the American Revolution some years earlier. An analysis of these two transitions using the comparative method advocated by Ma...

  11. A miniature single element effusion cell for the vacuum deposition of transition-metal and rare-earth elements

    Science.gov (United States)

    Harris, V. G.; Koon, N. C.

    1997-08-01

    A miniature single element effusion cell has been fabricated and tested that allows for the high-vacuum deposition of a variety of transition-metal and rare-earth elements. The cell is designed to operate under high-vacuum conditions, ≈10-9 Torr, with low power demands, <200 W. The virtues of this evaporator are the simplicity of design and ease of fabrication, assembly, maintenance, and operation.

  12. Reliable and efficient reaction path and transition state finding for surface reactions with the growing string method.

    Science.gov (United States)

    Jafari, Mina; Zimmerman, Paul M

    2017-04-15

    The computational challenge of fast and reliable transition state and reaction path optimization requires new methodological strategies to maintain low cost, high accuracy, and systematic searching capabilities. The growing string method using internal coordinates has proven to be highly effective for the study of molecular, gas phase reactions, but difficulties in choosing a suitable coordinate system for periodic systems has prevented its use for surface chemistry. New developments are therefore needed, and presented herein, to handle surface reactions which include atoms with large coordination numbers that cannot be treated using standard internal coordinates. The double-ended and single-ended growing string methods are implemented using a hybrid coordinate system, then benchmarked for a test set of 43 elementary reactions occurring on surfaces. These results show that the growing string method is at least 45% faster than the widely used climbing image-nudged elastic band method, which also fails to converge in several of the test cases. Additionally, the surface growing string method has a unique single-ended search method which can move outward from an initial structure to find the intermediates, transition states, and reaction paths simultaneously. This powerful explorative feature of single ended-growing string method is demonstrated to uncover, for the first time, the mechanism for atomic layer deposition of TiN on Cu(111) surface. This reaction is found to proceed through multiple hydrogen-transfer and ligand-exchange events, while formation of H-bonds stabilizes intermediates of the reaction. Purging gaseous products out of the reaction environment is the driving force for these reactions. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  13. Development of n- and p-type Doped Perovskite Single Crystals Using Solid-State Single Crystal Growth (SSCG) Technique

    Science.gov (United States)

    2017-10-09

    tried. Among them “n- and p-type doped” BaTiO3 single crystals have been successfully fabricated . And their bi- crystals containing a twin or twist...boundary are also fabricated using diffusion bonding process of two single crystal plates. These results demonstrate that the SSCG (solid-state...or Bridgman method have critical limitations; high production cost and compositional inhomogeneity throughout the crystal. These limitations result

  14. Immigration transition and depressive symptoms: four major ethnic groups of midlife women in the United States.

    Science.gov (United States)

    Im, Eun-Ok; Chang, Sun Ju; Chee, Wonshik; Chee, Eunice; Mao, Jun James

    2015-01-01

    The purpose of this study was to explore the relationships between immigration transition and depressive symptoms among 1,054 midlife women in the United States. This was a secondary analysis of the data from two national Internet survey studies. Questions on background characteristics and immigration transition and the Depression Index for Midlife Women were used to collect the data. The data were analyzed using inferential statistics including multiple regressions. Immigrants reported lower numbers of symptoms and less severe symptoms than nonimmigrants (p immigration status were significant predictors of depressive symptoms (R(2) =.01, p <.05).

  15. Theory of collisional excitation transition between Rydberg states of atoms. Non-inertial mechanism

    International Nuclear Information System (INIS)

    Kaulakys, B.P.

    1982-01-01

    The transitions between highly states of an atom due to the collision of its core with another atom are considered. The cross sections of the change of highly excited electron angular momentum, in the case of the transitions when the main quantum number is constant, are expressed in terms of transport cross sections of the perturbing atom scattering on the ion of Rydberg atom. It is shown that the cross sections of the momentum mixing at thermal rapidities are lower than the cross sections of the atom-ion elastic scattering

  16. Suppression of angular forces in collisions of non-S-state transition metal atoms

    International Nuclear Information System (INIS)

    Krems, R.V.; Klos, J.; Rode, M.F.; Szczesniak, M.M.; Chalasinski, G.; Dalgarno, A.

    2005-01-01

    Angular momentum transfer is expected to occur rapidly in collisions of atoms in states of nonzero angular momenta due to the large torque of angular forces. We show that despite the presence of internal angular momenta transition metal atoms interact in collisions with helium effectively as spherical atoms and angular momentum transfer is slow. Thus, magnetic trapping and sympathetic cooling of transition metal atoms to ultracold temperatures should be readily achievable. Our results open up new avenues of research with a broad class of ultracold atoms

  17. Structural and magnetic transitions in spinel FeM n2O4 single crystals

    Science.gov (United States)

    Nepal, Roshan; Zhang, Qiang; Dai, Samuel; Tian, Wei; Nagler, S. E.; Jin, Rongying

    2018-01-01

    Materials that form the spinel structure are known to exhibit geometric frustration, which can lead to magnetic frustration as well. Through magnetization and neutron diffraction measurements, we find that FeM n2O4 undergoes one structural and two magnetic transitions. The structural transition occurs at Ts˜595 K from cubic at high temperatures to tetragonal at low temperatures. Two magnetic transitions are ferrimagnetic at TFI -1˜373 K and TFI -2˜50 K , respectively. Further investigation of the specific heat, thermal conductivity, and Seebeck coefficient confirms both magnetic transitions. Of particular interest is that there is a significant magnetic contribution to the low-temperature specific heat and thermal conductivity, providing a unique system to study heat transport by magnetic excitations.

  18. Dynamically Switching the Polarization State of Light Based on the Phase Transition of Vanadium Dioxide

    Science.gov (United States)

    Jia, Zhi-Yong; Shu, Fang-Zhou; Gao, Ya-Jun; Cheng, Feng; Peng, Ru-Wen; Fan, Ren-Hao; Liu, Yongmin; Wang, Mu

    2018-03-01

    There have been great endeavors devoted to manipulating the polarization state of light by plasmonic nanostructures in recent decades. However, the topic of active polarizers has attracted much less attention. We present a composite plasmonic nanostructure consisting of vanadium dioxide that can dynamically modulate the polarization state of the reflected light through a thermally induced phase transition of vanadium dioxide. We design a system consisting of anisotropic plasmonic nanostructures with vanadium dioxide that exhibits distinct reflections subjected to different linearly polarized incidence at room temperature and in the heated state. Under a particular linearly polarized incidence, the polarization state of the reflected light changes at room temperature, and reverts to its original polarization state above the phase-transition temperature. The composite structure can also be used to realize a dynamically switchable infrared image, wherein a pattern can be visualized at room temperature while it disappears above the phase-transition temperature. The composite structure could be potentially used for versatile optical modulators, molecular detection, and polarimetric imaging.

  19. Generalization of the second law for a transition between nonequilibrium states

    Energy Technology Data Exchange (ETDEWEB)

    Takara, K. [Department of Mathematical Sciences, Ibaraki University, Bunkyo, Mito 310-8512 (Japan); Hasegawa, H.-H., E-mail: hhh@mx.ibaraki.ac.j [Department of Mathematical Sciences, Ibaraki University, Bunkyo, Mito 310-8512 (Japan); Center for Complex Quantum Systems, Univ. of Texas, Austin, TX 78712 (United States); Driebe, D.J. [Embry-Riddle Aeronautical University Worldwide, Fort Lauderdale, FL 33309 (United States)

    2010-12-01

    The maximum work formulation of the second law of thermodynamics is generalized for a transition between nonequilibrium states. The relative entropy, the Kullback-Leibler divergence between the nonequilibrium states and the canonical distribution, determines the maximum ability to work. The difference between the final and the initial relative entropies with an effective temperature gives the maximum dissipative work for both adiabatic and isothermal processes. Our formulation reduces to both the Vaikuntanathan-Jarzynski relation and the nonequilibrium Clausius relation in certain situations. By applying our formulation to a heat engine the Carnot cycle is generalized to a circulation among nonequilibrium states.

  20. Structure of transition nuclei states in fermion dynamic-symmetry model

    International Nuclear Information System (INIS)

    Baktybaev, K.; Kojlyk, N.O.; Romankulov, K.

    2007-01-01

    In the paper collective structures of osmium heavy isotopes nucleons are studied. Results of diagonalization of SO(6) symmetric Hamiltonian of fermion-dynamical symmetry-model are comparing with results of other phenomenological methods such as Bohr-Mottelson model and interacting bosons model. For heavy osmium isotopes not only collective excitations spectral bands but also for probability of E2-electromagnet transition are which are compared with existing experimental data. It is revealed, that complexity of state structure for examined nuclei is related with competition and interweaving of rotation and vibration states and also more complicated states of γ instable nature

  1. On matrix stabilisation of d- and f-transition metal ions in unstable oxidation states

    Energy Technology Data Exchange (ETDEWEB)

    Kiselev, Yurii M [Department of Chemistry, M.V. Lomonosov Moscow State University, Moscow (Russian Federation)

    2009-01-31

    The state-of-the-art in matrix stabilisation of d- and f-transition metal ions in unstable oxidation states is analysed. Main aspects of this problem concerning the genealogy of appropriate matrix systems are classified. Relevant examples are given and the data that contradict the scheme proposed are discussed. The thermodynamics of the matrix stabilisation effect is considered using the concept of isomorphic miscibility. The influence of defects and non-equilibrium on the matrix stabilisation effect is discussed. The problem of identification of the oxidation states in matrix systems is examined and various types of matrix systems are considered.

  2. On matrix stabilisation of d- and f-transition metal ions in unstable oxidation states

    International Nuclear Information System (INIS)

    Kiselev, Yurii M

    2009-01-01

    The state-of-the-art in matrix stabilisation of d- and f-transition metal ions in unstable oxidation states is analysed. Main aspects of this problem concerning the genealogy of appropriate matrix systems are classified. Relevant examples are given and the data that contradict the scheme proposed are discussed. The thermodynamics of the matrix stabilisation effect is considered using the concept of isomorphic miscibility. The influence of defects and non-equilibrium on the matrix stabilisation effect is discussed. The problem of identification of the oxidation states in matrix systems is examined and various types of matrix systems are considered.

  3. A universal indicator of critical state transitions in noisy complex networked systems.

    Science.gov (United States)

    Liang, Junhao; Hu, Yanqing; Chen, Guanrong; Zhou, Tianshou

    2017-02-23

    Critical transition, a phenomenon that a system shifts suddenly from one state to another, occurs in many real-world complex networks. We propose an analytical framework for exactly predicting the critical transition in a complex networked system subjected to noise effects. Our prediction is based on the characteristic return time of a simple one-dimensional system derived from the original higher-dimensional system. This characteristic time, which can be easily calculated using network data, allows us to systematically separate the respective roles of dynamics, noise and topology of the underlying networked system. We find that the noise can either prevent or enhance critical transitions, playing a key role in compensating the network structural defect which suffers from either internal failures or environmental changes, or both. Our analysis of realistic or artificial examples reveals that the characteristic return time is an effective indicator for forecasting the sudden deterioration of complex networks.

  4. Characteristics of homeless adults with serious mental illness served by a state mental health transitional shelter.

    Science.gov (United States)

    Viron, Mark; Bello, Iruma; Freudenreich, Oliver; Shtasel, Derri

    2014-07-01

    Specialized transitional shelters are available in various cities to provide assistance to homeless individuals with serious mental illness. Little is known about the population using such shelters. The authors conducted a retrospective chart review to collect demographic, social, and clinical data of residents in a state-operated mental health transitional shelter in Massachusetts. A total of 74 subjects were included. Schizophrenia-spectrum disorders were present in 67.6 % of the sample and mood disorders in 35.1 %. Substance use disorders were documented in 44.6 %. Chronic medical illness (mostly hypertension, dyslipidemia, asthma, and diabetes) was found in 82.4 %. The co-occurrence of a psychiatric and substance use disorder and chronic medical illness was found in 36.5 %. The majority (75.7 %) of patients had a history of legal charges. Homeless individuals with serious mental illness served by specialized transitional shelters represent a population with complex psychiatric, medical and social needs.

  5. 19 CFR 123.64 - Baggage in transit through the United States between ports in Canada or in Mexico.

    Science.gov (United States)

    2010-04-01

    ... between ports in Canada or in Mexico. 123.64 Section 123.64 Customs Duties U.S. CUSTOMS AND BORDER... MEXICO Baggage § 123.64 Baggage in transit through the United States between ports in Canada or in Mexico. (a) Procedure. Baggage in transit from point to point in Canada or Mexico through the United States...

  6. Operation of a quantum dot in the finite-state machine mode: Single-electron dynamic memory

    Energy Technology Data Exchange (ETDEWEB)

    Klymenko, M. V. [Department of Chemistry, University of Liège, B4000 Liège (Belgium); Klein, M. [The Fritz Haber Center for Molecular Dynamics and the Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904 (Israel); Levine, R. D. [The Fritz Haber Center for Molecular Dynamics and the Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904 (Israel); Crump Institute for Molecular Imaging and Department of Molecular and Medical Pharmacology, David Geffen School of Medicine and Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095 (United States); Remacle, F., E-mail: fremacle@ulg.ac.be [Department of Chemistry, University of Liège, B4000 Liège (Belgium); The Fritz Haber Center for Molecular Dynamics and the Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904 (Israel)

    2016-07-14

    A single electron dynamic memory is designed based on the non-equilibrium dynamics of charge states in electrostatically defined metallic quantum dots. Using the orthodox theory for computing the transfer rates and a master equation, we model the dynamical response of devices consisting of a charge sensor coupled to either a single and or a double quantum dot subjected to a pulsed gate voltage. We show that transition rates between charge states in metallic quantum dots are characterized by an asymmetry that can be controlled by the gate voltage. This effect is more pronounced when the switching between charge states corresponds to a Markovian process involving electron transport through a chain of several quantum dots. By simulating the dynamics of electron transport we demonstrate that the quantum box operates as a finite-state machine that can be addressed by choosing suitable shapes and switching rates of the gate pulses. We further show that writing times in the ns range and retention memory times six orders of magnitude longer, in the ms range, can be achieved on the double quantum dot system using experimentally feasible parameters, thereby demonstrating that the device can operate as a dynamic single electron memory.

  7. Operation of a quantum dot in the finite-state machine mode: Single-electron dynamic memory

    International Nuclear Information System (INIS)

    Klymenko, M. V.; Klein, M.; Levine, R. D.; Remacle, F.

    2016-01-01

    A single electron dynamic memory is designed based on the non-equilibrium dynamics of charge states in electrostatically defined metallic quantum dots. Using the orthodox theory for computing the transfer rates and a master equation, we model the dynamical response of devices consisting of a charge sensor coupled to either a single and or a double quantum dot subjected to a pulsed gate voltage. We show that transition rates between charge states in metallic quantum dots are characterized by an asymmetry that can be controlled by the gate voltage. This effect is more pronounced when the switching between charge states corresponds to a Markovian process involving electron transport through a chain of several quantum dots. By simulating the dynamics of electron transport we demonstrate that the quantum box operates as a finite-state machine that can be addressed by choosing suitable shapes and switching rates of the gate pulses. We further show that writing times in the ns range and retention memory times six orders of magnitude longer, in the ms range, can be achieved on the double quantum dot system using experimentally feasible parameters, thereby demonstrating that the device can operate as a dynamic single electron memory.

  8. Biomechanical effect of interspinous dynamic stabilization adjacent to single-level fusion on range of motion of the transition segment and the adjacent segment.

    Science.gov (United States)

    Kong, Chao; Lu, Shibao; Hai, Yong; Zang, Lei

    2015-05-01

    Despite numerous biomechanical studies have been carried out on dynamic stabilizers, there is very little information on their hybrid application, especially when combined interspinous dynamic stabilization with single-level fusion. The aim of this study is to assess the biomechanical effect of interspinous dynamic stabilization adjacent to single-level fusion on range of motion of the transition segment and the adjacent segment. Six fresh lumbosacral spines (L2-S1) were tested in the following sequence: 1) intact (Construct A); 2) fusion in L5/S1 and intact in L4/5 (Construct B); 3) fusion in L5/S1 and unstable state in L4/5 (Construct C); 4) fusion in L5/S1 and Coflex in L4/5 (Construct D). Range of motion (at L3/4 and L4/5) was recorded and calculated. Range of motion in L3/4 in the four constructs showed no difference under all motion states. Under flexion/extension, the range of motion of L4/5 in Construct B and Construct C increased, while the range of motion of L4/5 in Construct D decreased compared with Construct A. Compared with Construct D, the range of motion of L4/5 in Constructs B and C showed a significant increase. Under lateral bending and axial rotation, Construct A showed similar range of motion of L3/4 compared with other constructs. Fusion combined with Coflex is able to stabilize the transition segment and restrict flexion and extension in that segment, while having no significant effect on the range of motion of the adjacent segment or the range of motion of the transition segment under lateral bending and axial rotation. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. Unambiguous modification of nonorthogonal single- and two-photon polarization states

    International Nuclear Information System (INIS)

    Torres-Ruiz, F. A.; Aguirre, J.; Delgado, A.; Lima, G.; Neves, L.; Roa, L.; Saavedra, C.; Padua, S.

    2009-01-01

    In this paper we propose a probabilistic method which allows an unambiguous modification of two nonorthogonal quantum states. We experimentally implement this protocol by using two-photon polarization states generated in the process of spontaneous parametric down conversion. In the experiment, for codifying initial quantum states, we consider single-photon states and heralded detection. We show that the application of this protocol to entangled states allows a fine control of the amount of entanglement of the initial state.

  10. Integrating continuous stocks and flows into state-and-transition simulation models of landscape change

    Science.gov (United States)

    Daniel, Colin J.; Sleeter, Benjamin M.; Frid, Leonardo; Fortin, Marie-Josée

    2018-01-01

    State-and-transition simulation models (STSMs) provide a general framework for forecasting landscape dynamics, including projections of both vegetation and land-use/land-cover (LULC) change. The STSM method divides a landscape into spatially-referenced cells and then simulates the state of each cell forward in time, as a discrete-time stochastic process using a Monte Carlo approach, in response to any number of possible transitions. A current limitation of the STSM method, however, is that all of the state variables must be discrete.Here we present a new approach for extending a STSM, in order to account for continuous state variables, called a state-and-transition simulation model with stocks and flows (STSM-SF). The STSM-SF method allows for any number of continuous stocks to be defined for every spatial cell in the STSM, along with a suite of continuous flows specifying the rates at which stock levels change over time. The change in the level of each stock is then simulated forward in time, for each spatial cell, as a discrete-time stochastic process. The method differs from the traditional systems dynamics approach to stock-flow modelling in that the stocks and flows can be spatially-explicit, and the flows can be expressed as a function of the STSM states and transitions.We demonstrate the STSM-SF method by integrating a spatially-explicit carbon (C) budget model with a STSM of LULC change for the state of Hawai'i, USA. In this example, continuous stocks are pools of terrestrial C, while the flows are the possible fluxes of C between these pools. Importantly, several of these C fluxes are triggered by corresponding LULC transitions in the STSM. Model outputs include changes in the spatial and temporal distribution of C pools and fluxes across the landscape in response to projected future changes in LULC over the next 50 years.The new STSM-SF method allows both discrete and continuous state variables to be integrated into a STSM, including interactions between

  11. Integrating continuous stocks and flows into state-and-transition simulation models of landscape change

    Science.gov (United States)

    Daniel, Colin J.; Sleeter, Benjamin M.; Frid, Leonardo; Fortin, Marie-Josée

    2017-01-01

    State-and-transition simulation models (STSMs) provide a general framework for forecasting landscape dynamics, including projections of both vegetation and land-use/land-cover (LULC) change. The STSM method divides a landscape into spatially-referenced cells and then simulates the state of each cell forward in time, as a discrete-time stochastic process using a Monte Carlo approach, in response to any number of possible transitions. A current limitation of the STSM method, however, is that all of the state variables must be discrete.Here we present a new approach for extending a STSM, in order to account for continuous state variables, called a state-and-transition simulation model with stocks and flows (STSM-SF). The STSM-SF method allows for any number of continuous stocks to be defined for every spatial cell in the STSM, along with a suite of continuous flows specifying the rates at which stock levels change over time. The change in the level of each stock is then simulated forward in time, for each spatial cell, as a discrete-time stochastic process. The method differs from the traditional systems dynamics approach to stock-flow modelling in that the stocks and flows can be spatially-explicit, and the flows can be expressed as a function of the STSM states and transitions.We demonstrate the STSM-SF method by integrating a spatially-explicit carbon (C) budget model with a STSM of LULC change for the state of Hawai'i, USA. In this example, continuous stocks are pools of terrestrial C, while the flows are the possible fluxes of C between these pools. Importantly, several of these C fluxes are triggered by corresponding LULC transitions in the STSM. Model outputs include changes in the spatial and temporal distribution of C pools and fluxes across the landscape in response to projected future changes in LULC over the next 50 years.The new STSM-SF method allows both discrete and continuous state variables to be integrated into a STSM, including interactions between

  12. Critical high-dimensional state transitions in cell populations or why cancers follow the principle ``What does not kill me makes me stronger''

    Science.gov (United States)

    Huang, Sui

    Transitions between high-dimensional attractor states in the quasi-potential landscape of the gene regulatory network, induced by environmental perturbations and/or facilitated by mutational rewiring of the network, underlie cell phenotype switching in development as well as in cancer progression, including acquisition of drug-resistant phenotypes. Considering heterogeneous cell populations as statistical ensembles of cells, and single-cell resolution gene expression profiling of cell populations undergoing a cell phenotype shift allow us now to map the topography of the landscape and its distortion. From snapshots of single-cell expression patterns of a cell population measured during major transitions we compute a quantity that identifies symmetry-breaking destabilization of attractors (bifurcation) and concomitant dimension-reduction of the state space manifold (landscape distortion) which precede critical transitions to new attractor states. The model predicts, and we show experimentally, the almost inevitable generation of aberrant cells associated with such critical transitions in multi-attractor landscapes: therapeutic perturbations which seek to push cancer cells to the apoptotic state, almost always produce ``rebellious'' cells which move in the ``opposite direction'': instead of dying they become more stem-cell-like and malignant. We show experimentally that the inadvertent generation of more malignant cancer cells by therapy indeed results from transition of surviving (but stressed) cells into unforeseen attractor states and not simply from selection of inherently more resistant cells. Thus, cancer cells follow not so much Darwin, as generally thought (survival of the fittest), but rather Nietzsche (What does not kill me makes me stronger). Supported by NIH (NCI, NIGMS), Alberta Innovates.

  13. Heralded noiseless amplification for single-photon entangled state with polarization feature

    Science.gov (United States)

    Wang, Dan-Dan; Jin, Yu-Yu; Qin, Sheng-Xian; Zu, Hao; Zhou, Lan; Zhong, Wei; Sheng, Yu-Bo

    2018-03-01

    Heralded noiseless amplification is a promising method to overcome the transmission photon loss in practical noisy quantum channel and can effectively lengthen the quantum communication distance. Single-photon entanglement is an important resource in current quantum communications. Here, we construct two single-photon-assisted heralded noiseless amplification protocols for the single-photon two-mode entangled state and single-photon three-mode W state, respectively, where the single-photon qubit has an arbitrary unknown polarization feature. After the amplification, the fidelity of the single-photon entangled state can be increased, while the polarization feature of the single-photon qubit can be well remained. Both the two protocols only require the linear optical elements, so that they can be realized under current experimental condition. Our protocols may be useful in current and future quantum information processing.

  14. Stochastic transitions between neural states in taste processing and decision-making.

    Science.gov (United States)

    Miller, Paul; Katz, Donald B

    2010-02-17

    Noise, which is ubiquitous in the nervous system, causes trial-to-trial variability in the neural responses to stimuli. This neural variability is in turn a likely source of behavioral variability. Using Hidden Markov modeling, a method of analysis that can make use of such trial-to-trial response variability, we have uncovered sequences of discrete states of neural activity in gustatory cortex during taste processing. Here, we advance our understanding of these patterns in two ways. First, we reproduce the experimental findings in a formal model, describing a network that evinces sharp transitions between discrete states that are deterministically stable given sufficient noise in the network; as in the empirical data, the transitions occur at variable times across trials, but the stimulus-specific sequence is itself reliable. Second, we demonstrate that such noise-induced transitions between discrete states can be computationally advantageous in a reduced, decision-making network. The reduced network produces binary outputs, which represent classification of ingested substances as palatable or nonpalatable, and the corresponding behavioral responses of "spit" or "swallow". We evaluate the performance of the network by measuring how reliably its outputs follow small biases in the strengths of its inputs. We compare two modes of operation: deterministic integration ("ramping") versus stochastic decision-making ("jumping"), the latter of which relies on state-to-state transitions. We find that the stochastic mode of operation can be optimal under typical levels of internal noise and that, within this mode, addition of random noise to each input can improve optimal performance when decisions must be made in limited time.

  15. Relationship of Topology, Multiscale Phase Synchronization, and State Transitions in Human Brain Networks

    Directory of Open Access Journals (Sweden)

    Minkyung Kim

    2017-06-01

    Full Text Available How the brain reconstitutes consciousness and cognition after a major perturbation like general anesthesia is an important question with significant neuroscientific and clinical implications. Recent empirical studies in animals and humans suggest that the recovery of consciousness after anesthesia is not random but ordered. Emergence patterns have been classified as progressive and abrupt transitions from anesthesia to consciousness, with associated differences in duration and electroencephalogram (EEG properties. We hypothesized that the progressive and abrupt emergence patterns from the unconscious state are associated with, respectively, continuous and discontinuous synchronization transitions in functional brain networks. The discontinuous transition is explainable with the concept of explosive synchronization, which has been studied almost exclusively in network science. We used the Kuramato model, a simple oscillatory network model, to simulate progressive and abrupt transitions in anatomical human brain networks acquired from diffusion tensor imaging (DTI of 82 brain regions. To facilitate explosive synchronization, distinct frequencies for hub nodes with a large frequency disassortativity (i.e., higher frequency nodes linking with lower frequency nodes, or vice versa were applied to the brain network. In this simulation study, we demonstrated that both progressive and abrupt transitions follow distinct synchronization processes at the individual node, cluster, and global network levels. The characteristic synchronization patterns of brain regions that are “progressive and earlier” or “abrupt but delayed” account for previously reported behavioral responses of gradual and abrupt emergence from the unconscious state. The characteristic network synchronization processes observed at different scales provide new insights into how regional brain functions are reconstituted during progressive and abrupt emergence from the unconscious

  16. Single-particle and collective states in transfer reactions

    International Nuclear Information System (INIS)

    Lhenry, I.; Suomijaervi, T.; Giai, N. van

    1993-01-01

    The possibility to excite collective states in transfer reactions induced by heavy ions is studied. Collective states are described within the Random Phase Approximation (RPA) and the collectivity is defined according to the number of configurations contributing to a given state. The particle transfer is described within the Distorted Wave Born Approximation (DWBA). Calculations are performed for two different stripping reactions: 207 Pb( 20 Ne, 19 Ne) 208 Pb and 59 Co( 20 Ne, 19 F) 60 Ni at 48 MeV/nucleon for which experimental data are available. The calculation shows that a sizeable fraction of collective strength can be excited in these reactions. The comparison with experiment shows that this parameter-free calculation qualitatively explains the data. (author) 19 refs.; 10 figs

  17. The transition between energy efficient and energy inefficient states in Cameroon

    International Nuclear Information System (INIS)

    Adom, Philip Kofi

    2016-01-01

    I use a two-state (energy efficient/inefficient) Markov-switching dynamic model to study energy efficiency in Cameroon in a novel manner, employing yearly data covering 1971 to 2012. I find that the duration of an energy inefficient state is about twice as long as an energy efficient state, mainly due to fuel subsidies, low income, high corruption, regulatory inefficiencies, poorly developed infrastructure and undeveloped markets. To escape from an energy inefficient state a broad policy overhaul is needed. Trade liberalization and related growth policies together with the removal of fuel subsidies are useful, but insufficient policy measures; the results suggest that they should be combined with structural policies, aiming at institutional structure and investment in infrastructure. - Highlights: • I investigate the transition between energy efficient/inefficient states. • On the average, energy inefficient state persists more than energy efficient state. • The duration of energy inefficient state is about twice as long as energy efficient state. • Price, income and trade openness have distinct energy saving effect irrespective of state. • A broad policy overhaul is needed to escape the energy inefficient state.

  18. Study of radicals, clusters and transition state species by anion photoelectron spectroscopy

    International Nuclear Information System (INIS)

    Arnold, D.W.

    1994-08-01

    Free radicals, elemental and van der Waals clusters and transition state species for bimolecular chemical reactions are investigated using anion photoelectron spectroscopy. Several low-lying electronic states of ozone have been identified via photoelectron spectroscopy of O 3 - . A characterization of these states is important to models for atmospheric ozone reaction kinetics. The fluoroformyloxyl radical, FCO 2 , has been investigated, providing vibrational frequencies and energies for two electronic states. The technique has also been employed to make the first direct observation and characterization of the NNO 2 molecule. Several electronic states are observed for this species which is believed to play a role as a reactive intermediate in the N + NO 2 reaction. The experimental results for all three of these radicals are supplemented by ab initio investigations of their molecular properties. The clusters investigations include studies of elemental carbon clusters (C 2 - - C 11 - ), and van der Waals clusters (X - (CO 2 ) n , X = I, Br, Cl; n ≤ 13 and I - (N 2 O) n=1--11 ). Primarily linear clusters are observed for the smaller carbon clusters, while the spectra of the larger clusters contain contribution from cyclic anion photodetachment. Very interesting ion-solvent interactions are observed in the X - (CO 2 )n clusters. The transition state regions for several bimolecular chemical reactions have also been investigated by photodetachment of a negative ion precursor possessing a geometry similar to that of the transition state species. These spectra show features which are assigned to motions of the unstable neutral complex existing between reactants and products

  19. Study of radicals, clusters and transition state species by anion photoelectron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, Don Wesley [Univ. of California, Berkeley, CA (United States)

    1994-08-01

    Free radicals, elemental and van der Waals clusters and transition state species for bimolecular chemical reactions are investigated using anion photoelectron spectroscopy. Several low-lying electronic states of ozone have been identified via photoelectron spectroscopy of O3-. A characterization of these states is important to models for atmospheric ozone reaction kinetics. The fluoroformyloxyl radical, FCO2, has been investigated, providing vibrational frequencies and energies for two electronic states. The technique has also been employed to make the first direct observation and characterization of the NNO2 molecule. Several electronic states are observed for this species which is believed to play a role as a reactive intermediate in the N + NO2 reaction. The experimental results for all three of these radicals are supplemented by ab initio investigations of their molecular properties. The clusters investigations include studies of elemental carbon clusters (C2- - C11-), and van der Waals clusters (X-(CO2)n, X = I, Br, Cl; n {le} 13 and I- (N2O)n=1--11). Primarily linear clusters are observed for the smaller carbon clusters, while the spectra of the larger clusters contain contribution from cyclic anion photodetachment. Very interesting ion-solvent interactions are observed in the X-(CO2)n clusters. The transition state regions for several bimolecular chemical reactions have also been investigated by photodetachment of a negative ion precursor possessing a geometry similar to that of the transition state species. These spectra show features which are assigned to motions of the unstable neutral complex existing between reactants and products.

  20. Pressure controlled transition into a self-induced topological superconducting surface state

    KAUST Repository

    Zhu, Zhiyong

    2014-02-07

    Ab-initio calculations show a pressure induced trivial-nontrivial-trivial topological phase transition in the normal state of 1T-TiSe2. The pressure range in which the nontrivial phase emerges overlaps with that of the superconducting ground state. Thus, topological superconductivity can be induced in protected surface states by the proximity effect of superconducting bulk states. This kind of self-induced topological surface superconductivity is promising for a realization of Majorana fermions due to the absence of lattice and chemical potential mismatches. For appropriate electron doping, the formation of the topological superconducting surface state in 1T-TiSe 2 becomes accessible to experiments as it can be controlled by pressure.

  1. Heat capacity for systems with excited-state quantum phase transitions

    Energy Technology Data Exchange (ETDEWEB)

    Cejnar, Pavel; Stránský, Pavel, E-mail: stransky@ipnp.troja.mff.cuni.cz

    2017-03-18

    Heat capacities of model systems with finite numbers of effective degrees of freedom are evaluated using canonical and microcanonical thermodynamics. Discrepancies between both approaches, which are observed even in the infinite-size limit, are particularly large in systems that exhibit an excited-state quantum phase transition. The corresponding irregularity of the spectrum generates a singularity in the microcanonical heat capacity and affects smoothly the canonical heat capacity. - Highlights: • Thermodynamics of systems with excited-state quantum phase transitions • ESQPT-generated singularities of the microcanonical heat capacity • Non-monotonous dependences of the canonical heat capacity • Discord between canonical and microcanonical pictures in the infinite-size limit.

  2. Degree of Rate Control: How Much the Energies of Intermediates and Transition States Control Rates

    DEFF Research Database (Denmark)

    Stegelmann, Carsten; Andreasen, Anders; Campbell, Charles T.

    2009-01-01

    recently introduced, via the “degree of rate control” of elementary steps. By extending that idea, we argue that even more useful than identifying the rate-determining step is identifying the rate-controlling transition states and the rate-controlling intermediates. These identify a few distinct chemical...... electronic or steric control on the relative energies of the key species. Since these key species are the ones whose relative energies most strongly influence the net reaction rate, they also identify the species whose energetics must be most accurately measured or calculated to achieve an accurate kinetic...... model for any reaction mechanism. Thus, it is very important to identify these rate-controlling transition states and rate-controlling intermediates for both applied and basic research. Here, we present a method for doing that....

  3. A Study to Identify the Transitional Training Needs for United States Army Medical Residents

    Science.gov (United States)

    1988-07-29

    of no current effort tinder way to ascertain the transitional training needs for members of this most vital segment of the health care team. The goal...leadership development, office communi-ations, professional and legal obligations, Rawls 8 and practice marketing . Because these newly trained physicians...specialty. It is felt, though, that insufficient data were obtained on which to state such inferences. It is conceivable that psychographic

  4. Chapter 5: Application of state-and-transition models to evaluate wildlife habitat

    Science.gov (United States)

    Anita T. Morzillo; Pamela Comeleo; Blair Csuti; Stephanie Lee

    2014-01-01

    Wildlife habitat analysis often is a central focus of natural resources management and policy. State-and-transition models (STMs) allow for simulation of landscape level ecological processes, and for managers to test “what if” scenarios of how those processes may affect wildlife habitat. This chapter describes the methods used to link STM output to wildlife habitat to...

  5. Stereoselective synthesis of phosphoramidate alpha(2-6)sialyltransferase transition-state analogue inhibitors.

    Science.gov (United States)

    Skropeta, Danielle; Schwörer, Ralf; Schmidt, Richard R

    2003-10-06

    The asymmetric synthesis of novel, potent phosphoramidate alpha(2-6)sialyltransferase transition-state analogue inhibitors such as (R)-9 (K(i)=68 microM) is described, via condensation of cytidine phosphitamide 6 with key chiral, non-racemic alpha-aminophosphonates, prepared in >98% ee by Mitsunobu azidation followed by Staudinger reduction of the corresponding chiral, non-racemic alpha-hydroxyphosphonates.

  6. Transition State Theory for solvated reactions beyond recrossing-free dividing surfaces

    OpenAIRE

    Revuelta, F.; Bartsch, Thomas; Garcia-Muller, P. L.; Hernandez, Rigoberto; Benito, R. M.; Borondo, F.

    2016-01-01

    The accuracy of rate constants calculated using transition state theory depends crucially on the correct identification of a recrossing--free dividing surface. We show here that it is possible to define such optimal dividing surface in systems with non--Markovian friction. However, a more direct approach to rate calculation is based on invariant manifolds and avoids the use of a dividing surface altogether, Using that method we obtain an explicit expression for the rate of crossing an anharmo...

  7. Study on microstructure of transition zone and its strong contrast of single T700 carbon fibers

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Xinshuang; Zhang, Kexiang [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Fan, Zhen; Feng, Zhihai [National Key Laboratory of Advanced Functional Composite Materials, Aerospace Research Institute of Materials and Processing Technology, Beijing 100076 (China); He, LianLong, E-mail: llhe@imr.ac.cn [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China)

    2017-06-01

    Highlights: • The transition zone of T700 carbon fiber was first identified with higher density in addition to higher orientation. • The higher sample density still existed while the higher orientation disappeared after heat treatment at 2800 °C. • The strong contrast of the transition zone mainly results from its higher density. • The transition zone with higher density and orientation may exist not only in the T700 but other PAN-based carbon fibers. - Abstract: The transition zone (TZ) between the skin and core of Toray T700 carbon fiber was investigated by transmission electron microscopy. The higher basal-plane orientation was identified in the TZ compared with the skin and core, but it disappeared after heat treatment at 2800 °C. Plasmon peak energy in the TZ was higher than that in the skin and core about 0.7–0.8 eV, indicating the TZ with higher density. No element concentration existed in the TZ. The TZ with strong contrast manifests itself before and after heat treatment, and formation mechanism of its strong contrast was proposed.

  8. Afghanistan's Post-Taliban Transition: The State of State-Building After War

    National Research Council Canada - National Science Library

    Johnson, Thomas H

    2006-01-01

    ...: will it be stability and democracy, or a return to its chaotic and turbulent past? On the one hand, after decades of fighting, this volatile state has witnessed watershed elections and important infrastructure rebuilding...

  9. Muon-Substituted Malonaldehyde: Transforming a Transition State into a Stable Structure by Isotope Substitution.

    Science.gov (United States)

    Goli, Mohammad; Shahbazian, Shant

    2016-02-12

    Isotope substitutions are usually conceived to play a marginal role on the structure and bonding pattern of molecules. However, a recent study [Angew. Chem. Int. Ed. 2014, 53, 13706-13709; Angew. Chem. 2014, 126, 13925-13929] further demonstrates that upon replacing a proton with a positively charged muon, as the lightest radioisotope of hydrogen, radical changes in the nature of the structure and bonding of certain species may take place. The present report is a primary attempt to introduce another example of structural transformation on the basis of the malonaldehyde system. Accordingly, upon replacing the proton between the two oxygen atoms of malonaldehyde with the positively charged muon a serious structural transformation is observed. By using the ab initio nuclear-electronic orbital non-Born-Oppenheimer procedure, the nuclear configuration of the muon-substituted species is derived. The resulting nuclear configuration is much more similar to the transition state of the proton transfer in malonaldehyde rather than to the stable configuration of malonaldehyde. The comparison of the "atoms in molecules" (AIM) structure of the muon-substituted malonaldehyde and the AIM structure of the stable and the transition-state configurations of malonaldehyde also unequivocally demonstrates substantial similarities of the muon-substituted malonaldehyde to the transition state. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Magnetic states of single impurity in disordered environment

    Directory of Open Access Journals (Sweden)

    G.W. Ponedilok

    2013-01-01

    Full Text Available The charged and magnetic states of isolated impurities dissolved in amorphous metallic alloy are investigated. The Hamiltonian of the system under study is the generalization of Anderson impurity model. Namely, the processes of elastic and non-elastic scattering of conductive electrons on the ions of a metal and on a charged impurity are included. The configuration averaged one-particle Green's functions are obtained within Hartree-Fock approximation. A system of self-consistent equations is given for calculation of an electronic spectrum, the charged and the spin-polarized impurity states. Qualitative analysis of the effect of the metallic host structural disorder on the observed values is performed. Additional shift and broadening of virtual impurity level is caused by a structural disorder of impurity environment.

  11. Excitons and trions in monolayer transition metal dichalcogenides: A comparative study between the multiband model and the quadratic single-band model

    Science.gov (United States)

    Van der Donck, M.; Zarenia, M.; Peeters, F. M.

    2017-07-01

    The electronic and structural properties of excitons and trions in monolayer transition metal dichalcogenides are investigated using both a multiband and a single-band model. In the multiband model we construct the excitonic Hamiltonian in the product base of the single-particle states at the conduction and valence band edges. We decouple the corresponding energy eigenvalue equation and solve the resulting differential equation self-consistently, using the finite element method (FEM), to determine the energy eigenvalues and the wave functions. As a comparison, we also consider the simple single-band model which is often used in numerical studies. We solve the energy eigenvalue equation using the FEM as well as with the stochastic variational method (SVM) in which a variational wave function is expanded in a basis of a large number of correlated Gaussians. We find good agreement between the results of both methods, as well as with other theoretical works for excitons, and we also compare with available experimental data. For trions the agreement between both methods is not as good due to our neglect of angular correlations when using the FEM. Finally, when comparing the two models, we see that the presence of the valence bands in the mutiband model leads to differences with the single-band model when (interband) interactions are strong.

  12. Vison states and confinement transitions of Z2 spin liquids on the kagome lattice

    Science.gov (United States)

    Huh, Yejin; Punk, Matthias; Sachdev, Subir

    2011-09-01

    We present a projective symmetry group (PSG) analysis of the spinless excitations of Z2 spin liquids on the kagome lattice. In the simplest case, vortices carrying Z2 magnetic flux (“visons”) are shown to transform under the 48 element group GL(2,Z3). Alternative exchange couplings can also lead to a second case with visons transforming under 288-element group GL(2,Z3)×D3. We study the quantum phase transition in which visons condense into confining states with valence bond solid order. The critical field theories and confining states are classified using the vison PSGs.

  13. Increased Firing Irregularity as an Emergent Property of Neural-State Transition in Monkey Prefrontal Cortex

    Science.gov (United States)

    Sakamoto, Kazuhiro; Katori, Yuichi; Saito, Naohiro; Yoshida, Shun; Aihara, Kazuyuki; Mushiake, Hajime

    2013-01-01

    Flexible behaviors are organized by complex neural networks in the prefrontal cortex. Recent studies have suggested that such networks exhibit multiple dynamical states, and can switch rapidly from one state to another. In many complex systems such as the brain, the early-warning signals that may predict whether a critical threshold for state transitions is approaching are extremely difficult to detect. We hypothesized that increases in firing irregularity are a crucial measure for predicting state transitions in the underlying neuronal circuits of the prefrontal cortex. We used both experimental and theoretical approaches to test this hypothesis. Experimentally, we analyzed activities of neurons in the prefrontal cortex while monkeys performed a maze task that required them to perform actions to reach a goal. We observed increased firing irregularity before the activity changed to encode goal-to-action information. Theoretically, we constructed theoretical generic neural networks and demonstrated that changes in neuronal gain on functional connectivity resulted in a loss of stability and an altered state of the networks, accompanied by increased firing irregularity. These results suggest that assessing the temporal pattern of neuronal fluctuations provides important clues regarding the state stability of the prefrontal network. We also introduce a novel scheme that the prefrontal cortex functions in a metastable state near the critical point of bifurcation. According to this scheme, firing irregularity in the prefrontal cortex indicates that the system is about to change its state and the flow of information in a flexible manner, which is essential for executive functions. This metastable and/or critical dynamical state of the prefrontal cortex may account for distractibility and loss of flexibility in the prefrontal cortex in major mental illnesses such as schizophrenia. PMID:24349020

  14. First-order phase transitions in CaFe2As2 single crystal: a local probe study

    International Nuclear Information System (INIS)

    Alzamora, M; Munevar, J; Baggio-Saitovitch, E; Bud'ko, S L; Ni Ni; Canfield, P C; Sanchez, D R

    2011-01-01

    57 Fe Moessbauer spectroscopy has been used to investigate the structural and magnetic phase transitions of CaFe 2 As 2 (T N = 173 K) single crystals. For this compound we found that V ZZ is positive and parallel to the c-axis of the tetragonal structure. For CaFe 2 As 2 a magnetic hyperfine field B hf was observed at the 57 Fe nucleus below T N ∼ 173 K. Analysis of the temperature dependence of B hf data using the Bean-Rodbell model shows that the Fe spins undergo a first-order magnetic transition at ∼ 173 K. A collinear antiferromagnetic structure is established below this temperature with the Fe spin lying in the (a, b) plane. Below T N the paramagnetic fraction of Fe decreases down to 150 K and for lower temperatures all the Fe spins are magnetically ordered.

  15. Thermal expansion and cooling rate dependence of transition temperature in ZrTiO4 single crystal

    International Nuclear Information System (INIS)

    Park, Y.

    1998-01-01

    Thermal expansion in ZrTiO 4 single crystal was investigated in the temperature range covering the normal, incommensurate, and commensurate phases. Remarkable change was found at the normal-incommensurate phase transition (T I ) in all thermal expansion coefficients a, b, and c. The spontaneous strains χ as and χ bs along the a and b axes show linear temperature dependence, while the spontaneous strain χ cs along the c axis shows a nonlinear temperature dependence. Small discontinuity along the c direction was observed at the incommensurate-commensurate transition temperature, T c = 845 C. dT I /dP and dT c /dP depend on the cooling rate

  16. State-and-transition prototype model of riparian vegetation downstream of Glen Canyon Dam, Arizona

    Science.gov (United States)

    Ralston, Barbara E.; Starfield, Anthony M.; Black, Ronald S.; Van Lonkhuyzen, Robert A.

    2014-01-01

    Facing an altered riparian plant community dominated by nonnative species, resource managers are increasingly interested in understanding how to manage and promote healthy riparian habitats in which native species dominate. For regulated rivers, managing flows is one tool resource managers consider to achieve these goals. Among many factors that can influence riparian community composition, hydrology is a primary forcing variable. Frame-based models, used successfully in grassland systems, provide an opportunity for stakeholders concerned with riparian systems to evaluate potential riparian vegetation responses to alternative flows. Frame-based, state-and-transition models of riparian vegetation for reattachment bars, separation bars, and the channel margin found on the Colorado River downstream of Glen Canyon Dam were constructed using information from the literature. Frame-based models can be simple spreadsheet models (created in Microsoft® Excel) or developed further with programming languages (for example, C-sharp). The models described here include seven community states and five dam operations that cause transitions between states. Each model divides operations into growing (April–September) and non-growing seasons (October–March) and incorporates upper and lower bar models, using stage elevation as a division. The inputs (operations) can be used by stakeholders to evaluate flows that may promote dynamic riparian vegetation states, or identify those flow options that may promote less desirable states (for example, Tamarisk [Tamarix sp.] temporarily flooded shrubland). This prototype model, although simple, can still elicit discussion about operational options and vegetation response.

  17. Transition paths of Met-enkephalin from Markov state modeling of a molecular dynamics trajectory.

    Science.gov (United States)

    Banerjee, Rahul; Cukier, Robert I

    2014-03-20

    Conformational states and their interconversion pathways of the zwitterionic form of the pentapeptide Met-enkephalin (MetEnk) are identified. An explicit solvent molecular dynamics (MD) trajectory is used to construct a Markov state model (MSM) based on dihedral space clustering of the trajectory, and transition path theory (TPT) is applied to identify pathways between open and closed conformers. In the MD trajectory, only four of the eight backbone dihedrals exhibit bistable behavior. Defining a conformer as the string XXXX with X = "+" or "-" denoting, respectively, positive or negative values of a given dihedral angle and obtaining the populations of these conformers shows that only four conformers are highly populated, implying a strong correlation among these dihedrals. Clustering in dihedral space to construct the MSM finds the same four bistable dihedral angles. These state populations are very similar to those found directly from the MD trajectory. TPT is used to obtain pathways, parametrized by committor values, in dihedral state space that are followed in transitioning from closed to open states. Pathway costs are estimated by introducing a kinetics-based procedure that orders pathways from least (shortest) to greater cost paths. The least costly pathways in dihedral space are found to only involve the same XXXX set of dihedral angles, and the conformers accessed in the closed to open transition pathways are identified. For these major pathways, a correlation between reaction path progress (committors) and the end-to-end distance is identified. A dihedral space principal component analysis of the MD trajectory shows that the first three modes capture most of the overall fluctuation, and pick out the same four dihedrals having essentially all the weight in those modes. A MSM based on root-mean-square backbone clustering was also carried out, with good agreement found with dihedral clustering for the static information, but with results that differ

  18. Conformation transitions of a single polyelectrolyte chain in a poor solvent: a replica-exchange lattice Monte-Carlo study.

    Science.gov (United States)

    Wang, Lang; Wang, Zheng; Jiang, Run; Yin, Yuhua; Li, Baohui

    2017-03-15

    The thermodynamic behaviors of a strongly charged polyelectrolyte chain in a poor solvent are studied using replica-exchange Monte-Carlo simulations on a lattice model, focusing on the effects of finite chain length and the solvent quality on the chain conformation and conformation transitions. The neutralizing counterions and solvent molecules are considered explicitly. The thermodynamic quantities that vary continuously with temperature over a wide range are computed using the multiple histogram reweighting method. Our results suggest that the strength of the short-range hydrophobic interaction, the chain length, and the temperature of the system, characterized by ε, N, and T, respectively, are important parameters that control the conformations of a charged chain. When ε is moderate, the competition between the electrostatic energy and the short-range hydrophobic interaction leads to rich conformations and conformation transitions for a longer chain with a fixed length. Our results have unambiguously demonstrated the stability of the n-pearl-necklace structures, where n has a maximum value and decreases with decreasing temperature. The maximum n value increases with increasing chain length. Our results have also demonstrated the first-order nature of the conformation transitions between the m-pearl and the (m-1)-pearl necklaces. With the increase of ε, the transition temperature increases and the first-order feature becomes more pronounced. It is deduced that at the thermodynamic limit of infinitely long chain length, the conformational transitions between the m-pearl and the (m-1)-pearl necklaces may remain first order when ε > 0 and m = 2 or 3. Pearl-necklace conformations cannot be observed when either ε is too large or N is too small. To observe a pearl-necklace conformation, the T value needs to be carefully chosen for simulations performed at only a single temperature.

  19. Commissioning of the ATLAS Transition Radiation Tracker with Cosmic Rays and single LHC beams

    CERN Document Server

    Cwetanski, P; The ATLAS collaboration

    2009-01-01

    The ATLAS Transition Radiation Tracker (TRT) is the outermost of the three subsystems of the ATLAS Inner Detector at the Large Hadron Collider at CERN. It consists of close to 300000 thin-wall drift tubes (straws) providing on average 35 two-dimensional space points with 0.17 mm resolution for charged particle tracks with pT > 0.5 GeV within |η| < 2. Transition radiation X-rays, generated by particles with γ > 1000 in the special material between the straws, are absorbed in the Xenon based gas mixture and give rise to large signal amplitudes. The front-end electronics implements two thresholds to discriminate the signals: a low threshold (< 300 eV) for registering the passage of minimum ionizing particles, and a high threshold (> 6 keV) to flag the absorption of transition radiation X-rays. The talk will report on the commissioning and first operational experience of the TRT detector and its sophisticated off-detector systems for cooling, active gas, lo...

  20. Agricultural Drought Transition Periods In the United States Corn Belt Region

    Science.gov (United States)

    Schiraldi, Nicholas J.

    Agricultural drought in the U.S. Corn Belt region (CBR) has tremendous global socioeconomic implications. Unfortunately, the weather and climate factors that contribute to transition events toward or away from such droughts, and how well those factors are predicted, are poorly understood. This dissertation focuses on the atmospheric circulation signals associated with agricultural drought transitions periods in the CBR that evolve over 20 and 60 days, and how well those circulation signals are predicted on seasonal to sub-seasonal time scales. Results show that amplification of an intraseasonal Rossby wave train across the Pacific Ocean into North America, which occurs coincident with intraseasonal tropical convection on its equatorward side, triggers these transition events, not shifts in the low frequency base state. This result is confirmed through composite analysis, trajectory analysis and a vertically integrated moisture budget. Trajectory analysis reveals similar source regions for air parcels associated with drought development and breakdown, but with a shift toward more parcels originating over the Gulf of Mexico during transitions away from drought. The primary result from the vertically integrated moisture budget demonstrates that advection and convergence of moisture on intraseasonal time scales dominates during these transitions. The primary conclusion drawn is that weather events are the primary driver of agricultural drought transitions occurring over 20 and 60 days. The seasonal to sub-seasonal hindcast dataset is used to investigate the prediction of the low frequency, intraseasonal and synoptic circulation patterns associated with 20 and 60-day drought transition periods. The forecast models assessed are the European Centre for Medium Range Prediction (ECMWF), National Center for Environment Prediction Climate Forecast System (NCEP) and the Australian Bureau of Meteorology (BoM). Results demonstrate that ECMWF and NCEP are not skillful in

  1. The effect of a low-frequency noise signal on a single-frequency millimeter-band oscillator based on an avalanche-transit diode

    Science.gov (United States)

    Kotov, V. D.; Myasin, E. A.

    2017-11-01

    Noise-wave generation in a single-frequency oscillator based on a 7-mm-band avalanche-transit diode has been implemented for the first time under the action of a low-frequency narrow-band ( 3 MHz) noise signal on an avalanche-transit-diode feed circuit.

  2. Single and two-mode mechanical squeezing of an optically levitated nanodiamond via dressed-state coherence

    Science.gov (United States)

    Ge, Wenchao; Bhattacharya, M.

    2016-10-01

    Nonclassical states of macroscopic objects are promising for ultrasensitive metrology as well as testing quantum mechanics. In this work, we investigate dissipative mechanical quantum state engineering in an optically levitated nanodiamond. First, we study single-mode mechanical squeezed states by magnetically coupling the mechanical motion to a dressed three-level system provided by a nitrogen-vacancy center in the nanoparticle. Quantum coherence between the dressed levels is created via microwave fields to induce a two-phonon transition, which results in mechanical squeezing. Remarkably, we find that in ultrahigh vacuum quantum squeezing is achievable at room temperature with feedback cooling. For moderate vacuum, quantum squeezing is possible with cryogenic temperature. Second, we present a setup for two mechanical modes coupled to the dressed three levels, which results in two-mode squeezing analogous to the mechanism of the single-mode case. In contrast to previous works, our study provides a deterministic method for engineering macroscopic squeezed states without the requirement for a cavity.

  3. Encapsulating model complexity and landscape-scale analyses of state-and-transition simulation models: an application of ecoinformatics and juniper encroachment in sagebrush steppe ecosystems

    Science.gov (United States)

    O'Donnell, Michael

    2015-01-01

    State-and-transition simulation modeling relies on knowledge of vegetation composition and structure (states) that describe community conditions, mechanistic feedbacks such as fire that can affect vegetation establishment, and ecological processes that drive community conditions as well as the transitions between these states. However, as the need for modeling larger and more complex landscapes increase, a more advanced awareness of computing resources becomes essential. The objectives of this study include identifying challenges of executing state-and-transition simulation models, identifying common bottlenecks of computing resources, developing a workflow and software that enable parallel processing of Monte Carlo simulations, and identifying the advantages and disadvantages of different computing resources. To address these objectives, this study used the ApexRMS® SyncroSim software and embarrassingly parallel tasks of Monte Carlo simulations on a single multicore computer and on distributed computing systems. The results demonstrated that state-and-transition simulation models scale best in distributed computing environments, such as high-throughput and high-performance computing, because these environments disseminate the workloads across many compute nodes, thereby supporting analysis of larger landscapes, higher spatial resolution vegetation products, and more complex models. Using a case study and five different computing environments, the top result (high-throughput computing versus serial computations) indicated an approximate 96.6% decrease of computing time. With a single, multicore compute node (bottom result), the computing time indicated an 81.8% decrease relative to using serial computations. These results provide insight into the tradeoffs of using different computing resources when research necessitates advanced integration of ecoinformatics incorporating large and complicated data inputs and models. - See more at: http://aimspress.com

  4. Using a State-and-Transition Approach to Manage Endangered Eucalyptus albens (White Box) Woodlands

    Science.gov (United States)

    Spooner, Peter G.; Allcock, Kimberly G.

    2006-11-01

    Eucalyptus albens (White Box) woodlands are among the most poorly conserved and threatened communities in Australia. Remnants are under further threat from stock grazing, deteriorating soil conditions, weed invasion, and salinity. There is an urgent need to restore degraded White Box and other woodland ecosystems to improve landscape function. However, there is still a poor understanding of the ecology of degraded woodland ecosystems in fragmented agricultural landscapes, and consequently a lack of precise scientific guidelines to manage these ecosystems in a conservation context. State and Transition Models (STMs) have received a great deal of attention, mainly in rangeland applications, as a suitable framework for understanding the ecology of complex ecosystems and to guide management. We have developed a STM for endangered White Box woodlands and discuss the merits of using this approach for land managers of other endangered ecosystems. An STM approach provides a greater understanding of the range of states, transitions, and thresholds possible in an ecosystem, and provides a summary of processes driving the system. Importantly, our proposed STM could be used to clarify the level of “intactness” of degraded White Box woodland sites, and provide the impetus to manage different states in complementary ways, rather than attempting to restore ecosystems to one pristine stable state. We suggest that this approach has considerable potential to integrate researcher and land manager knowledge, focus future experimental studies, and ultimately serve as a decision support tool in setting realistic and achievable conservation and restoration goals.

  5. Lithium tantalate single crystal for pyroelectricity-based laser energy-meter: growth, application and phase transition study

    International Nuclear Information System (INIS)

    Bhaumik, Indranil; Ganesamoorthy, S.; Bhatt, R.; Karnal, A.K.; Gupta, P.K.

    2009-01-01

    Single crystals of lithium tantalate have been grown. Dielectric-spectroscopy study reveals phase transition in congruent lithium tantalate (CLT) single crystal is diffusive and frequency dependent in contrast to that in near stoichiometric lithium tantalate where it is sharper. The ac conductivity measurements show that the conductivity is lower for 0.5Mg-SLT as compared to 1.0Mg-SLT. This is explained in terms of a Li-vacancy model. Calculation of activation energy from the lnσ vs. 1000/T plot reveals that hopping of Li + ions becomes difficult for 0.5 Mg-SLT. The pyroelectric response of CLT for pulsed Nd:YAG laser output has been tested. (author)

  6. Time-gated single-photon detection module with 110 ps transition time and up to 80 MHz repetition rate

    Energy Technology Data Exchange (ETDEWEB)

    Buttafava, Mauro, E-mail: mauro.buttafava@polimi.it; Boso, Gianluca; Ruggeri, Alessandro; Tosi, Alberto [Politecnico di Milano, Dipartimento di Elettronica, Informazione e Bioingegneria, Piazza Leonardo Da Vinci 32, 20133 Milano (Italy); Dalla Mora, Alberto [Politecnico di Milano, Dipartimento di Fisica, Piazza Leonardo Da Vinci 32, 20133 Milano (Italy)

    2014-08-15

    We present the design and characterization of a complete single-photon counting module capable of time-gating a silicon single-photon avalanche diode with ON and OFF transition times down to 110 ps, at repetition rates up to 80 MHz. Thanks to this sharp temporal filtering of incoming photons, it is possible to reject undesired strong light pulses preceding (or following) the signal of interest, allowing to increase the dynamic range of optical acquisitions up to 7 decades. A complete experimental characterization of the module highlights its very flat temporal response, with a time resolution of the order of 30 ps. The instrument is fully user-configurable via a PC interface and can be easily integrated in any optical setup, thanks to its small and compact form factor.

  7. Genome-wide diel growth state transitions in the diatom Thalassiosira pseudonana.

    Science.gov (United States)

    Ashworth, Justin; Coesel, Sacha; Lee, Allison; Armbrust, E Virginia; Orellana, Mónica V; Baliga, Nitin S

    2013-04-30

    Marine diatoms are important primary producers that thrive in diverse and dynamic environments. They do so, in theory, by sensing changing conditions and adapting their physiology accordingly. Using the model species Thalassiosira pseudonana, we conducted a detailed physiological and transcriptomic survey to measure the recurrent transcriptional changes that characterize typical diatom growth in batch culture. Roughly 40% of the transcriptome varied significantly and recurrently, reflecting large, reproducible cell-state transitions between four principal states: (i) "dawn," following 12 h of darkness; (ii) "dusk," following 12 h of light; (iii) exponential growth and nutrient repletion; and (iv) stationary phase and nutrient depletion. Increases in expression of thousands of genes at the end of the reoccurring dark periods (dawn), including those involved in photosynthesis (e.g., ribulose-1,5-bisphosphate carboxylase oxygenase genes rbcS and rbcL), imply large-scale anticipatory circadian mechanisms at the level of gene regulation. Repeated shifts in the transcript levels of hundreds of genes encoding sensory, signaling, and regulatory functions accompanied the four cell-state transitions, providing a preliminary map of the highly coordinated gene regulatory program under varying conditions. Several putative light sensing and signaling proteins were associated with recurrent diel transitions, suggesting that these genes may be involved in light-sensitive and circadian regulation of cell state. These results begin to explain, in comprehensive detail, how the diatom gene regulatory program operates under varying environmental conditions. Detailed knowledge of this dynamic molecular process will be invaluable for new hypothesis generation and the interpretation of genetic, environmental, and metatranscriptomic data from field studies.

  8. The Relationship of Anticipatory Gluteus Medius Activity to Pelvic and Knee Stability in the Transition to Single-Leg Stance.

    Science.gov (United States)

    Kim, Daehan; Unger, Janelle; Lanovaz, Joel L; Oates, Alison R

    2016-02-01

    The knee abduction moment in a weight-bearing limb is an important risk factor of conditions such as patellofemoral pain and knee osteoarthritis. Excessive pelvic drop in single-leg stance can increase the knee abduction moment. The gluteus medius muscle is crucial to prevent pelvic drop and must be activated in anticipation of the transition from double-leg to single-leg stance. To examine the relationship of anticipatory activity of the gluteus medius to pelvic drop and knee abduction moment. Observational, cross-sectional correlational study. Research laboratory. Twenty female adults (mean age 22.6 years, standard deviation 2.5) were recruited and fully participated. Participant selection was limited to healthy women who did not have a history of knee and ankle ligament injuries, any indication of knee, hip, and/or low back pain, and/or knowledge of the proper squat technique. Participants performed 16 single-leg mini squats on their nondominant leg. The onset and magnitude of anticipatory gluteus medius activity were measured in relation to toe-off of the dominant leg during the transition from double-leg to single-leg stance. Preplanned correlations between anticipatory gluteus medius onset and its activation magnitude, pelvic obliquity, and knee abduction moment were examined. The magnitude of anticipatory gluteus medius activity was significantly correlated with the knee abduction moment (rs (18) = -0.303, P pelvic obliquity (rs (18) = 0.361, P pelvic obliquity. The amount of gluteus medius activity is more important for controlling knee and pelvic stability in the frontal plane than the onset of activation. Copyright © 2016 American Academy of Physical Medicine and Rehabilitation. Published by Elsevier Inc. All rights reserved.

  9. Angle and Polarization Dependent Fluorescence EXAFS Measurements on Al-doped Single Crystal V_2O3 Above and Below the Transition Temperature

    Science.gov (United States)

    Müller, O.; Pfalzer, P.; Schramme, M.; Urbach, J.-P.; Klemm, M.; Horn, S.; Frenkel, A. I.; Denboer, M. L.

    1998-03-01

    We present angle and polarisation dependent flourescence EXAFS measured on Al-doped single crystal V_2O3 below and above the structural phase transition from monoclinic to trigonal. Strong self-absorption distorted the spectra; this was corrected by using the procedure described by Tröger et al. (L. Tröger, D. Arvantis, K. Baberschke, H. Michaelis, U. Grimm, and E. Zschech, Phys. Rev. B,.46), 3238 (1992), generalized to the Lytle detector employed in our work. The spectra show pronounced dependence on the angle between the threefold symmetry axes and the polarization of the incident photons, making it possible to measure the local atomic distances in different directions. We compare our results with the measurements of Frenkel et al. (A. I. Frenkel, E. A. Stern, and F. A. Chudnovsky, Sol. State Comm.102), 637 (1997) on pure V_2O3 They found that locally the monoclinic distortion persists in the trigonal metallic phase.

  10. Study on microstructure of transition zone and its strong contrast of single T700 carbon fibers

    Science.gov (United States)

    Guo, Xinshuang; Zhang, Kexiang; Fan, Zhen; Feng, Zhihai; He, LianLong

    2017-06-01

    The transition zone (TZ) between the skin and core of Toray T700 carbon fiber was investigated by transmission electron microscopy. The higher basal-plane orientation was identified in the TZ compared with the skin and core, but it disappeared after heat treatment at 2800 °C. Plasmon peak energy in the TZ was higher than that in the skin and core about 0.7-0.8 eV, indicating the TZ with higher density. No element concentration existed in the TZ. The TZ with strong contrast manifests itself before and after heat treatment, and formation mechanism of its strong contrast was proposed.

  11. Communication: Evaluating non-empirical double hybrid functionals for spin-state energetics in transition-metal complexes

    Science.gov (United States)

    Wilbraham, Liam; Adamo, Carlo; Ciofini, Ilaria

    2018-01-01

    The computationally assisted, accelerated design of inorganic functional materials often relies on the ability of a given electronic structure method to return the correct electronic ground state of the material in question. Outlining difficulties with current density functionals and wave function-based approaches, we highlight why double hybrid density functionals represent promising candidates for this purpose. In turn, we show that PBE0-DH (and PBE-QIDH) offers a significant improvement over its hybrid parent functional PBE0 [as well as B3LYP* and coupled cluster singles and doubles with perturbative triples (CCSD(T))] when computing spin-state splitting energies, using high-level diffusion Monte Carlo calculations as a reference. We refer to the opposing influence of Hartree-Fock (HF) exchange and MP2, which permits higher levels of HF exchange and a concomitant reduction in electronic density error, as the reason for the improved performance of double-hybrid functionals relative to hybrid functionals. Additionally, using 16 transition metal (Fe and Co) complexes, we show that low-spin states are stabilised by increasing contributions from MP2 within the double hybrid formulation. Furthermore, this stabilisation effect is more prominent for high field strength ligands than low field strength ligands.

  12. Symptoms experienced during menopausal transition: Korean women in South Korea and the United States.

    Science.gov (United States)

    Im, Eun-Ok

    2003-10-01

    This article reports on cultural influences on symptoms experienced during menopausal transition of Korean women in South Korea and Korean immigrant women in the United States. Data from independent studies of two groups of Korean women were triangulated and analyzed using descriptive and inferential statistics. The analysis indicated that Korean women in South Korea tended to report more symptoms than Korean immigrant women in the United States. Types and severity of prevalent symptoms were also found to be different between the two groups. The findings suggest that recent introduction of menopausal industries in South Korea and contextual influences on Korean women's work and immigration in the United States would be the reason for differences. Based on the findings, implications for future research are proposed.

  13. Nonequilibrium steady states in correlated electron systems - Photoinduced insulator-metal transition and optical response

    International Nuclear Information System (INIS)

    Tsuji, Naoto; Oka, Takashi; Aoki, Hideo

    2010-01-01

    To reveal the nature of the photoinduced insulator-metal transition, we show that an exact analysis of the Falicov-Kimball model subject to external ac electric fields becomes possible with Floquet's method combined with the nonequilibrium dynamical mean-field theory. The nonequilibrium steady state that appears during irradiation of a pump light is shown to be determined if the dissipation in a certain heat-bath model is introduced. This has enabled us to predict that novel features characteristic of the photoexcited steady states, i.e., negative weight (gain) in the low-energy region and dip structures around the photon energy of the pump light, should be observed in the optical conductivity. Special emphasis is put on the role of dissipation, for which we elaborate the dependence of the steady state on the strength of dissipation and the temperature of the heat bath.

  14. Enhanced Prognostic Model for Lithium Ion Batteries Based on Particle Filter State Transition Model Modification

    Directory of Open Access Journals (Sweden)

    Buddhi Arachchige

    2017-11-01

    Full Text Available This paper focuses on predicting the End of Life and End of Discharge of Lithium ion batteries using a battery capacity fade model and a battery discharge model. The proposed framework will be able to estimate the Remaining Useful Life (RUL and the Remaining charge through capacity fade and discharge models. A particle filter is implemented that estimates the battery’s State of Charge (SOC and State of Life (SOL by utilizing the battery’s physical data such as voltage, temperature, and current measurements. The accuracy of the prognostic framework has been improved by enhancing the particle filter state transition model to incorporate different environmental and loading conditions without retuning the model parameters. The effect of capacity fade in the reduction of the EOD (End of Discharge time with cycling has also been included, integrating both EOL (End of Life and EOD prediction models in order to get more accuracy in the estimations.

  15. Deterministic Electrical Charge-State Initialization of Single Nitrogen-Vacancy Center in Diamond

    Directory of Open Access Journals (Sweden)

    Y. Doi

    2014-03-01

    Full Text Available Apart from applications in classical information-processing devices, the electrical control of atomic defects in solids at room temperature will have a tremendous impact on quantum devices that are based on such defects. In this study, we demonstrate the electrical manipulation of individual prominent representatives of such atomic solid-state defects, namely, the negative charge state of single nitrogen-vacancy defect centers (NV^{−} in diamond. We experimentally demonstrate, deterministic, purely electrical charge-state initialization of individual NV centers. The NV centers are placed in the intrinsic region of a p-i-n diode structure that facilitates the delivery of charge carriers to the defect for charge-state switching. The charge-state dynamics of a single NV center were investigated by time-resolved measurements and a nondestructive single-shot readout of the charge state. Fast charge-state switching rates (from negative to neutrally charged defects, which are greater than 0.72 ± 0.10  μs^{−1}, were realized. Furthermore, in no-operation mode, the realized charge states were stable for presumably much more than 0.45 s. We believe that the results obtained are useful not only for ultrafast electrical control of qubits, long T_{2} quantum memory, and quantum sensors associated with single NV centers but also for classical memory devices based on single atomic storage bits working under ambient conditions.

  16. Single-crystal X-ray and neutron powder diffraction investigation of the phase transition in tetrachlorobenzene.

    Science.gov (United States)

    Barnett, Sarah A; Broder, Charlotte K; Shankland, Kenneth; David, William I F; Ibberson, Richard M; Tocher, Derek A

    2006-04-01

    The polymorphic phase transition of 1,2,4,5-tetrachlorobenzene (TCB) has been investigated using neutron powder diffraction and single-crystal X-ray diffraction. The diffraction experiments show a reversible phase change that occurs as a function of temperature with no apparent loss of sample quality on transition between the two phases. Neutron powder diffraction gives detailed information on the molecular structural changes and lattice parameters from 2 K to room temperature. The structure of the low-temperature form has been elucidated for the first time using single-crystal X-ray diffraction. Comparison of the alpha and beta structures show that they are both based on the same sheet motif, with the differences between the two being very subtle, except in terms of crystal symmetry. Detailed analysis of the structures revealed the changes required for inter-conversion. A computational polymorph search showed that these two sheet structures are more thermodynamically stable than alternative herringbone-type structures.

  17. Single-dose and steady-state pharmacokinetics of diltiazem administered in two different tablet formulations

    DEFF Research Database (Denmark)

    Christrup, Lona Louring; Bonde, J; Rasmussen, S N

    1992-01-01

    Single-dose and steady state pharmacokinetics of diltiazem administered in two different oral formulations were assessed with particular reference to rate and extent of absorption. Following single dose administration a significant difference in tmax was observed (2.9 +/- 1.9 and 6.8 +/- 2.6 hr r...

  18. Investigation of the state of polarization of light in a single-mode fiber waveguide

    Science.gov (United States)

    Kozel, S. M.; Kreopalov, V. I.; Listvin, V. N.; Glavatskikh, N. A.

    1983-01-01

    An analysis is made of the polarization anisotropy of a single-mode fiber with a twisted elliptic core. The Jones matrix is obtained and the complex function of the state of polarization of light in a fiber is investigated. The results are reported of measurements of the linear and circular birefringence of a borosilicate single-mode glass fiber.

  19. Powder keg divisions in the critical state regime: transition from continuous to explosive percolation

    Science.gov (United States)

    Zhou, Zongzheng; Tordesillas, Antoinette

    2017-06-01

    The underlying microstructure and dynamics of a dense granular material as it evolves towards the "critical state", a limit state in which the system deforms with an essentially constant volume and stress ratio, remains widely debated in the micromechanics of granular media community. Strain localization, a common mechanism in the large strain regime, further complicates the characterization of this limit state. Here we revisit the evolution to this limit state within the framework of modern percolation theory. Attention is paid to motion transfer: in this context, percolation translates to the emergence of a large-scale connectivity in graphs that embody information on individual grain displacements. We construct each graph G(r) by connecting nodes, representing the grains, within a distance r in the displacement-state-space. As r increases, we observe a percolation transition on G(r). The size of the jump discontinuity increases in the lead up to failure, indicating that the nature of percolation transition changes from continuous to explosive. We attribute this to the emergence of collective motion, which manifests in increasingly isolated communities in G(r). At the limit state, where the jump discontinuity is highest and invariant across the different unjamming cycles (drops in stress ratio), G(r) encapsulates multiple kinematically distinct communities that are mediated by nodes corresponding to those grains in the shear band. This finding casts light on the dual and opposing roles of the shear band: a mechanism that creates powder keg divisions in the sample, while simultaneously acting as a mechanical link that transfers motion through such subdivisions moving in relative rigid-body motion.

  20. Adult bone strength of children from single-parent families: the Midlife in the United States Study.

    Science.gov (United States)

    Crandall, C J; Karlamangla, A S; Merkin, S S; Binkley, N; Carr, D; Greendale, G A; Seeman, T E

    2015-03-01

    Bone health may be negatively impacted by childhood socio-environmental circumstances. We examined the independent associations of single-parent childhood and parental death or divorce in childhood with adult bone strength indices. Longer exposure to a single-parent household in childhood was associated with lower bone strength in adulthood. Because peak bone mass is acquired during childhood, bone health may be negatively impacted by childhood socio-environmental disadvantage. The goal of this study was to determine whether being raised in a single-parent household is associated with lower bone strength in adulthood. Using dual-energy X-ray absorptiometry data from 708 participants (mean age 57 years) in the Midlife in the United States Biomarker Project, we examined the independent associations of composite indices of femoral neck bone strength relative to load (in three failure modes: compression, bending, and impact) in adulthood with the experience of single-parent childhood and parental death or divorce in childhood. After adjustment for gender, race, menopause transition stage, age, and body mass index, each additional year of single-parent childhood was associated with 0.02 to 0.03 SD lower indices of adult femoral neck strength. In those with 9-16 years of single-parent childhood, the compression strength index was 0.41 SD lower, bending strength index was 0.31 SD lower, and impact strength index was 0.25 SD lower (all p values divorce during childhood was not by itself independently associated with adult bone strength indices. The magnitudes of these associations were unaltered by additional adjustment for lifestyle factors and socioeconomic status in childhood and adulthood. Independent of parental death or divorce, growing up in a single-parent household is associated with lower femoral neck bone strength in adulthood, and this association is not entirely explained by childhood or adult socioeconomic conditions or lifestyle choices.

  1. Practical Considerations Concerning the Interleaved Transition Mode Single-stage Ballast

    DEFF Research Database (Denmark)

    Teodorescu, Remus; Kjær, Søren Bækhøj; Munk-Nielsen, Stig

    2002-01-01

    The aim of this paper is to present a novel single-stage interleaved ballast focusing on practical design aspects like: key current expression, overall losses, harmonic analysis of the differential-mode EMI current and preheating ballast function. A new preheating method is also presented. A PSPI...

  2. Edge states in the climate system: exploring global instabilities and critical transitions

    Science.gov (United States)

    Lucarini, Valerio; Bódai, Tamás

    2017-07-01

    Multistability is a ubiquitous feature in systems of geophysical relevance and provides key challenges for our ability to predict a system’s response to perturbations. Near critical transitions small causes can lead to large effects and—for all practical purposes—irreversible changes in the properties of the system. As is well known, the Earth climate is multistable: present astronomical and astrophysical conditions support two stable regimes, the warm climate we live in, and a snowball climate characterized by global glaciation. We first provide an overview of methods and ideas relevant for studying the climate response to forcings and focus on the properties of critical transitions in the context of both stochastic and deterministic dynamics, and assess strengths and weaknesses of simplified approaches to the problem. Following an idea developed by Eckhardt and collaborators for the investigation of multistable turbulent fluid dynamical systems, we study the global instability giving rise to the snowball/warm multistability in the climate system by identifying the climatic edge state, a saddle embedded in the boundary between the two basins of attraction of the stable climates. The edge state attracts initial conditions belonging to such a boundary and, while being defined by the deterministic dynamics, is the gate facilitating noise-induced transitions between competing attractors. We use a simplified yet Earth-like intermediate complexity climate model constructed by coupling a primitive equations model of the atmosphere with a simple diffusive ocean. We refer to the climatic edge states as Melancholia states and provide an extensive analysis of their features. We study their dynamics, their symmetry properties, and we follow a complex set of bifurcations. We find situations where the Melancholia state has chaotic dynamics. In these cases, we have that the basin boundary between the two basins of attraction is a strange geometric set with a nearly zero

  3. Analysis of the chloroplast protein kinase Stt7 during state transitions.

    Directory of Open Access Journals (Sweden)

    Sylvain Lemeille

    2009-03-01

    Full Text Available State transitions allow for the balancing of the light excitation energy between photosystem I and photosystem II and for optimal photosynthetic activity when photosynthetic organisms are subjected to changing light conditions. This process is regulated by the redox state of the plastoquinone pool through the Stt7/STN7 protein kinase required for phosphorylation of the light-harvesting complex LHCII and for the reversible displacement of the mobile LHCII between the photosystems. We show that Stt7 is associated with photosynthetic complexes including LHCII, photosystem I, and the cytochrome b6f complex. Our data reveal that Stt7 acts in catalytic amounts. We also provide evidence that Stt7 contains a transmembrane region that separates its catalytic kinase domain on the stromal side from its N-terminal end in the thylakoid lumen with two conserved Cys that are critical for its activity and state transitions. On the basis of these data, we propose that the activity of Stt7 is regulated through its transmembrane domain and that a disulfide bond between the two lumen Cys is essential for its activity. The high-light-induced reduction of this bond may occur through a transthylakoid thiol-reducing pathway driven by the ferredoxin-thioredoxin system which is also required for cytochrome b6f assembly and heme biogenesis.

  4. Dynamics of Number of Packets in Transit in Free Flow State of Data Network

    International Nuclear Information System (INIS)

    Shengkun Xie; Lawniczak, A.T.

    2011-01-01

    We study how the dynamics of Number of Packets in Transit (NPT) is affected by the coupling of a routing type with a volume of incoming packet traffic in a data network model of packet switching type. The NPT is a network performance indicator of an aggregate type that measures in '' real time '', how many packets are in the network on their routes to their destinations. We conduct our investigation using a time-discrete simulation model that is an abstraction of the Network Layer of the ISO OSI Seven Layer Reference Model. This model focuses on packets and their routing. We consider a static routing and two different types of dynamic routings coupled with different volumes of incoming packet traffic in the network free flow state. Our study shows that the order of the values of the NPT mean value time series depends on the coupling of a routing type with a volume of incoming packet traffic and changes when the volume of incoming packet traffic increases and is closed to the critical source load values, i.e. when it is closed to the phase transition points from the network free flow state to its congested states. (authors)

  5. Variational transition-state theory. Progress report, February 1981-January 1983

    International Nuclear Information System (INIS)

    Truhlar, D.G.

    1983-01-01

    During the past two years we have extended the variational transition-state theory in several ways. Especially notable is that we have developed several new methods for calculating tunneling probabilities, including two general techniques applicable to systems with small and large reaction-path curvature. We have tested these methods successfully against accurate quantal calculations, and we have applied them to real systems in three dimensions. We have also developed general algorithms for variational transition state theory calculations on polyatomic systems and we have applied these to the combustion reaction OH + H 2 → H 2 O + H. We have developed and successfully applied a statistical-diabatic theory for state-selected rates. We made a totally ab initio prediction of an absolute chemical reaction rate, for the reaction Mu + H 2 → MuH + H, using an accurate potential energy surface and ethods that we had demonstrated to be reliable by tests against accurate quantal collinear results. This prediction has now been confirmed by unpublished experiments; I believe that this is the first reliable ab initio prediction of a chemical rection rate prior to its measurement. In the rest of this technical progress report we give further details of these and other studies we have carried out in the last two years under this contract

  6. Modulating energy arriving at photochemical reaction centers: orange carotenoid protein-related photoprotection and state transitions.

    Science.gov (United States)

    Kirilovsky, Diana

    2015-10-01

    Photosynthetic organisms tightly regulate the energy arriving to the reaction centers in order to avoid photodamage or imbalance between the photosystems. To this purpose, cyanobacteria have developed mechanisms involving relatively rapid (seconds to minutes) changes in the photosynthetic apparatus. In this review, two of these processes will be described: orange carotenoid protein(OCP)-related photoprotection and state transitions which optimize energy distribution between the two photosystems. The photoactive OCP is a light intensity sensor and an energy dissipater. Photoactivation depends on light intensity and only the red-active OCP form, by interacting with phycobilisome cores, increases thermal energy dissipation at the level of the antenna. A second protein, the "fluorescence recovery protein", is needed to recover full antenna capacity under low light conditions. This protein accelerates OCP conversion to the inactive orange form and plays a role in dislodging the red OCP protein from the phycobilisome. The mechanism of state transitions is still controversial. Changes in the redox state of the plastoquinone pool induce movement of phycobilisomes and/or photosystems leading to redistribution of energy absorbed by phycobilisomes between PSII and PSI and/or to changes in excitation energy spillover between photosystems. The different steps going from the induction of redox changes to movement of phycobilisomes or photosystems remain to be elucidated.

  7. Expression of coxsackie and adenovirus receptor distinguishes transitional cancer states in therapy-induced cellular senescence.

    Science.gov (United States)

    Wu, P C; Wang, Q; Dong, Z M; Chu, E; Roberson, R S; Ivanova, I C; Wu, D Y

    2010-09-02

    Therapy-induced cellular senescence describes the phenomenon of cell cycle arrest that can be invoked in cancer cells in response to chemotherapy. Sustained proliferative arrest is often overcome as a contingent of senescent tumor cells can bypass this cell cycle restriction. The mechanism regulating cell cycle re-entry of senescent cancer cells remains poorly understood. This is the first report of the isolation and characterization of two distinct transitional states in chemotherapy-induced senescent cells that share indistinguishable morphological senescence phenotypes and are functionally classified by their ability to escape cell cycle arrest. It has been observed that cell surface expression of coxsackie and adenovirus receptor (CAR) is downregulated in cancer cells treated with chemotherapy. We show the novel use of surface CAR expression and adenoviral transduction to differentiate senescent states and also show in vivo evidence of CAR downregulation in colorectal cancer patients treated with neoadjuvant chemoradiation. This study suggests that CAR is a candidate biomarker for senescence response to antitumor therapy, and CAR expression can be used to distinguish transitional states in early senescence to study fundamental regulatory events in therapy-induced senescence.

  8. Are boat transition states likely to occur in Cope rearrangements? A DFT study of the biogenesis of germacranes

    Directory of Open Access Journals (Sweden)

    José Enrique Barquera-Lozada

    2017-09-01

    Full Text Available It has been proposed that elemanes are biogenetically formed from germacranes by Cope sigmatropic rearrangements. Normally, this reaction proceeds through a transition state with a chair conformation. However, the transformation of schkuhriolide (germacrane into elemanschkuhriolide (elemane may occur through a boat transition state due to the final configuration of the elemanschkuhriolide, but this transition state is questionable due to its high energy. The possible mechanisms of this transformation were studied in the density functional theory frame. The mechanistic differences between the transformation of (Z,E-germacranes and (E,E-germacranes were also studied. We found that (Z,E-germacranolides are significantly more stable than (E,E-germacranolides and elemanolides. In the specific case of schkuhriolide, even when the boat transition state is not energetically favored, a previous hemiacetalization lowers enough the energetic barrier to allow the formation of a very stable elemanolide that is even more stable than its (Z,E-germacrane.

  9. Study of the strength distribution of primary γ-transitions in the decay from superdeformed states in 194Hg

    International Nuclear Information System (INIS)

    Lopez-Martens, A.P.; Doessing, T.; Khoo, T.L.; Korichi, A.; Hannachi, F.; Calderin, I.J.; Lauritsen, T.; Ahmad, I.; Carpenter, M.P.; Fischer, S.M.; Hackman, G.; Janssens, R.V.F.; Nisius, D.; Reiter, P.; Amro, H.; Moore, E.F.

    1999-01-01

    The strength distribution of the primary γ rays in the decay from superdeformed (SD) states is investigated by applying the maximum likelihood method. For the 194 Hg nucleus, 41 primary transitions are identified above 2600 keV. It is concluded that they represent the strongest 10% of the transitions selected stochastically from a Porter-Thomas distribution. This would support the scenario of a statistical decay of SD states via coupling to a compound state at normal deformation. However, the occurrence of several very strong 'one-step linking' transitions is found to have a very small probability. Based on the absence of strong primary transitions from SD states in adjacent nuclei, the situation in 194 Hg is viewed as a very lucky incidence

  10. Transition state theory demonstrated at the micron scale with out-of-equilibrium transport in a confined environment

    DEFF Research Database (Denmark)

    Vestergaard, Christian L.; Mikkelsen, Morten Bo Lindholm; Reisner, Walter

    2016-01-01

    Transition state theory (TST) provides a simple interpretation of many thermally activated processes. It applies successfully on timescales and length scales that differ several orders of magnitude: to chemical reactions, breaking of chemical bonds, unfolding of proteins and RNA structures...

  11. Tropical Forest Restoration within Galapagos National Park: Application of a State-transition Model

    Directory of Open Access Journals (Sweden)

    S. R. Wilkinson

    2005-06-01

    Full Text Available Current theory on non-equilibrium communities, thresholds of irreversibility, and ecological resilience suggests the goal of ecological restoration of degraded communities is not to achieve one target, but to reestablish the temporal and spatial diversity inherent in natural ecosystems. Few restoration models, however, address ecological and management issues across the vegetation mosaic of a landscape. Because of a lack of scientific knowledge and funds, restoration practitioners focus instead on site-specific prescriptions and reactive rather than proactive approaches to restoration; this approach often dooms restoration projects to failure. We applied a state-transition model as a decision-making tool to identify and achieve short- and long-term restoration goals for a tropical, moist, evergreen forest on the island of Santa Cruz, Galapagos. The model guided the process of identifying current and desirable forest states, as well as the natural and human disturbances and management actions that caused transitions between them. This process facilitated assessment of opportunities for ecosystem restoration, expansion of the definition of restoration success for the system, and realization that, although site- or species-specific prescriptions may be available, they cannot succeed until broader landscape restoration issues are identified and addressed. The model provides a decision-making framework to allocate resources effectively to maximize these opportunities across the landscape, and to achieve long-term restoration success. Other restoration models have been limited by lack of scientific knowledge of the system. State-transition models for restoration incorporate current knowledge and funds, are adaptive, and can provide direction for restoration research and conservation management in other degraded systems.

  12. Recycling nicotinamide. The transition-state structure of human nicotinamide phosphoribosyltransferase

    Science.gov (United States)

    Burgos, Emmanuel S.; Vetticatt, Mathew J.; Schramm, Vern L.

    2013-01-01

    Human nicotinamide phosphoribosyltransferase (NAMPT) replenishes the NAD pool and controls the activities of sirtuins (SIRT), mono- and poly-(ADP-ribose) polymerases (PARP) and NAD nucleosidase (CD38). The nature of the enzymatic transition-state (TS) is central to understanding the function of NAMPT. We determined the TS structure for pyrophosphorolysis of nicotinamide mononucleotide (NMN) by kinetic isotope effects (KIEs). With the natural substrates, NMN and pyrophosphate (PPi), the intrinsic KIEs of [1′-14C], [1-15N], [1′-3H] and [2′-3H] are 1.047, 1.029, 1.154 and 1.093, respectively. A unique quantum computational approach was used for TS analysis that included structural elements of the catalytic site. Without constraints (e.g. imposed torsion angles), the theoretical and experimental data are in good agreement. The quantum-mechanical calculations incorporated a crucial catalytic site residue (D313), two magnesium atoms and coordinated water molecules. The transition state model predicts primary 14C, α-secondary 3H, β-secondary 3H and primary 15N KIE close to the experimental values. The analysis reveals significant ribocation character at the TS. The attacking PPi nucleophile is weakly interacting (rC-O = 2.60 Å) and the N-ribosidic C1′-N bond is highly elongated at the TS (rC-N = 2.35 Å), consistent with an ANDN mechanism. Together with the crystal structure of the NMN•PPi•Mg2•enzyme complex, the reaction coordinate is defined. The enzyme holds the nucleophile and leaving group in relatively fixed positions to create a reaction coordinate with C1′-anomeric migration from nicotinamide to the PPi. The transition state is reached by a 0.85 Å migration of C1′. PMID:23373462

  13. A transition-state based rotational sudden (TSRS) approximation for polyatomic reactive scattering.

    Science.gov (United States)

    Zhao, Bin; Manthe, Uwe

    2017-10-14

    A transition-state based rotational sudden (TSRS) approximation for the calculation of differential and integral cross sections is introduced. The TSRS approach only requires data obtained from reactive scattering calculations for the vanishing total angular momentum (J = 0). It is derived within the quantum transition state framework and can be viewed as a generalization and improvement of existing J-shifting schemes. The TSRS approach assumes a sudden decay of the activated complex and separability of the overall rotation and motion in the internal coordinates. Depending on the choice of the body fixed frame, different variants of the TSRS can be derived. The TSRS approach is applied to the calculation of integral cross sections of various isotopomers of the H 2 O+H→H 2 +OH reaction, the reverse reaction H 2 +OH→H 2 O+H, and the H 2 O+Cl→HCl+OH reaction. Comparison with accurate close-coupling calculations and established approximate schemes shows that a scattering frame based TSRS approximation yields more accurate results than the centrifugal sudden approximation and standard J-shifting for the H 2 O+H→H 2 +OH reaction and all isotopomers studied. For the H 2 +OH→H 2 O+H and the H 2 O+Cl→HCl+OH reactions, the TSRS results as well as the results of the other approximate schemes agree well with the exact ones. The findings are rationalized by an analysis of the different contributions to the moment of inertia matrix at the transition state geometry.

  14. Detection of a single enzyme molecule based on a solid-state nanopore sensor.

    Science.gov (United States)

    Tan, ShengWei; Gu, DeJian; Liu, Hang; Liu, QuanJun

    2016-04-15

    The nanopore sensor as a high-throughput and low-cost technology can detect a single molecule in a solution. In the present study, relatively large silicon nitride (Si3N4) nanopores with diameters of ∼28 and ∼88 nm were fabricated successfully using a focused Ga ion beam. We have used solid-state nanopores with various sizes to detect the single horseradish peroxidase (HRP) molecule and for the first time analyzed single HRP molecular translocation events. In addition, a real-time monitored single enzyme molecular biochemical reaction and a translocation of the product of enzyme catalysis substrates were investigated by using a Si3N4 nanopore. Our nanopore system showed a high sensitivity in detecting single enzyme molecules and a real-time monitored single enzyme molecular biochemical reaction. This method could also be significant for studying gene expression or enzyme dynamics at the single-molecule level.

  15. High-fidelity state detection and tomography of a single-ion Zeeman qubit

    International Nuclear Information System (INIS)

    Keselman, A; Glickman, Y; Akerman, N; Kotler, S; Ozeri, R

    2011-01-01

    We demonstrate high-fidelity Zeeman qubit state detection in a single trapped 88 Sr + ion. Qubit readout is performed by shelving one of the qubit states to a metastable level using a narrow linewidth diode laser at 674 nm, followed by state-selective fluorescence detection. The average fidelity reached for the readout of the qubit state is 0.9989(1). We then measure the fidelity of state tomography, averaged over all possible single-qubit states, which is 0.9979(2). We also fully characterize the detection process using quantum process tomography. This readout fidelity is compatible with recent estimates of the detection error threshold required for fault-tolerant computation, whereas high-fidelity state tomography opens the way for high-precision quantum process tomography.

  16. High-fidelity state detection and tomography of a single-ion Zeeman qubit

    Energy Technology Data Exchange (ETDEWEB)

    Keselman, A; Glickman, Y; Akerman, N; Kotler, S; Ozeri, R, E-mail: ozeri@weizmann.ac.il [Physics of Complex Systems, Weizmann Institute of Science, Rehovot 76100 (Israel)

    2011-07-15

    We demonstrate high-fidelity Zeeman qubit state detection in a single trapped {sup 88}Sr{sup +} ion. Qubit readout is performed by shelving one of the qubit states to a metastable level using a narrow linewidth diode laser at 674 nm, followed by state-selective fluorescence detection. The average fidelity reached for the readout of the qubit state is 0.9989(1). We then measure the fidelity of state tomography, averaged over all possible single-qubit states, which is 0.9979(2). We also fully characterize the detection process using quantum process tomography. This readout fidelity is compatible with recent estimates of the detection error threshold required for fault-tolerant computation, whereas high-fidelity state tomography opens the way for high-precision quantum process tomography.

  17. Density induced phase transitions in the Schwinger model. A study with matrix product states

    Energy Technology Data Exchange (ETDEWEB)

    Banuls, Mari Carmen; Cirac, J. Ignacio; Kuehn, Stefan [Max-Planck-Institut fuer Quantenoptik (MPQ), Garching (Germany); Cichy, Krzysztof [Frankfurt Univ. (Germany). Inst. fuer Theoretische Physik; Adam Mickiewicz Univ., Poznan (Poland). Faculty of Physics; Jansen, Karl [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC

    2017-02-15

    We numerically study the zero temperature phase structure of the multiflavor Schwinger model at nonzero chemical potential. Using matrix product states, we reproduce analytical results for the phase structure for two flavors in the massless case and extend the computation to the massive case, where no analytical predictions are available. Our calculations allow us to locate phase transitions in the mass-chemical potential plane with great precision and provide a concrete example of tensor networks overcoming the sign problem in a lattice gauge theory calculation.

  18. An experimental spatio-temporal state transition of coupled magneto-elastic system.

    Science.gov (United States)

    Hikihara, Takashi; Okamoto, Yoshinobu; Ueda, Yoshisuke

    1997-12-01

    In this paper the vibration and the traveling wave in a coupled magneto-elastic beam system are discussed experimentally. The vibration excited by the periodical forcing at the beam system propagates to another as a wave through the coupling elastic beams. Each magneto-elastic beam shows the variety of vibrations caused by the nonlinearity of the potential well and the wave propagation with time delay. The temporal vibration of the magneto-elastic beam is explained with relations to the spatial state transition based on the experimental results. (c) 1997 American Institute of Physics.

  19. Transition state determination of enzyme reaction on free energy surface: Application to chorismate mutase

    Science.gov (United States)

    Higashi, Masahiro; Hayashi, Shigehiko; Kato, Shigeki

    2007-04-01

    The transition state on the free energy surface for Claisen rearrangement of chorismate in Bacillus subtilis chorismate mutase is calculated with a method based on a linear response theory. The calculated activation free energy is 16.9 kcal/mol, which is in good agreement with the experimental one. The catalytic ability of the enzyme is examined by comparing the activation barrier with that in aqueous solution and found to be mainly attributed to the conformational restriction of the substrate. We also calculate the kinetic isotope effects, which are in accord with the experimental estimates.

  20. Monte Carlo method for determining free-energy differences and transition state theory rate constants

    International Nuclear Information System (INIS)

    Voter, A.F.

    1985-01-01

    We present a new Monte Carlo procedure for determining the Helmholtz free-energy difference between two systems that are separated in configuration space. Unlike most standard approaches, no integration over intermediate potentials is required. A Metropolis walk is performed for each system, and the average Metropolis acceptance probability for a hypothetical step along a probe vector into the other system is accumulated. Either classical or quantum free energies may be computed, and the procedure is also ideally suited for evaluating generalized transition state theory rate constants. As an application we determine the relative free energies of three configurations of a tungsten dimer on the W(110) surface

  1. The Welfare to Work Transition in the United States: Implications for Work-Related Learning

    Science.gov (United States)

    Fisher, James C.; Martin, Larry G.

    2000-11-01

    This paper summarizes the legislation upon which the current welfare-to-work transition in the United States is based and describes characteristics of the former welfare population from which various tiers of employment options have emerged: unsubsidized-employed workers, subsidized-employed workers, subsidized-unemployed recipients, and unsubsidized-unemployed individuals. It also discusses current program emphases, and presents a format for directions for future program development which includes academic programs, situated cognition programs, integrated literacy/occupational skills programs, and integrated literacy/soft skills training.

  2. Core-state models for fuel management of equilibrium and transition cycles in pressurized water reactors

    Energy Technology Data Exchange (ETDEWEB)

    Aragones, J.M.; Martinez-Val, J.M.; Corella, M.R.

    1977-08-01

    Fuel management requires that mass, energy, and reactivity balance be satisfied in each reload cycle. Procedures for selection of alternatives, core-state models, and fuel cost calculations have been developed for both equilibrium and transition cycles. Effective cycle lengths and fuel cycle variables--namely, reload batch size, schedule of incore residence for the fuel, feed enrichments, energy sharing cycle by cycle, and discharge burnup and isotopics--are the variables being considered for fuel management planning with a given energy generation plan, fuel design, recycling strategy, and financial assumptions.

  3. Surface hopping, transition state theory and decoherence. I. Scattering theory and time-reversibility.

    Science.gov (United States)

    Jain, Amber; Herman, Michael F; Ouyang, Wenjun; Subotnik, Joseph E

    2015-10-07

    We provide an in-depth investigation of transmission coefficients as computed using the augmented-fewest switches surface hopping algorithm in the low energy regime. Empirically, microscopic reversibility is shown to hold approximately. Furthermore, we show that, in some circumstances, including decoherence on top of surface hopping calculations can help recover (as opposed to destroy) oscillations in the transmission coefficient as a function of energy; these oscillations can be studied analytically with semiclassical scattering theory. Finally, in the spirit of transition state theory, we also show that transmission coefficients can be calculated rather accurately starting from the curve crossing point and running trajectories forwards and backwards.

  4. Transition state theory for solvated reactions beyond recrossing-free dividing surfaces.

    Science.gov (United States)

    Revuelta, F; Bartsch, Thomas; Garcia-Muller, P L; Hernandez, Rigoberto; Benito, R M; Borondo, F

    2016-06-01

    The accuracy of rate constants calculated using transition state theory depends crucially on the correct identification of a recrossing-free dividing surface. We show here that it is possible to define such optimal dividing surface in systems with non-Markovian friction. However, a more direct approach to rate calculation is based on invariant manifolds and avoids the use of a dividing surface altogether, Using that method we obtain an explicit expression for the rate of crossing an anharmonic potential barrier. The excellent performance of our method is illustrated with an application to a realistic model for LiNC⇌LiCN isomerization.

  5. Probing the Quantum States of a Single Atom Transistor at Microwave Frequencies.

    Science.gov (United States)

    Tettamanzi, Giuseppe Carlo; Hile, Samuel James; House, Matthew Gregory; Fuechsle, Martin; Rogge, Sven; Simmons, Michelle Y

    2017-03-28

    The ability to apply gigahertz frequencies to control the quantum state of a single P atom is an essential requirement for the fast gate pulsing needed for qubit control in donor-based silicon quantum computation. Here, we demonstrate this with nanosecond accuracy in an all epitaxial single atom transistor by applying excitation signals at frequencies up to ≈13 GHz to heavily phosphorus-doped silicon leads. These measurements allow the differentiation between the excited states of the single atom and the density of states in the one-dimensional leads. Our pulse spectroscopy experiments confirm the presence of an excited state at an energy ≈9 meV, consistent with the first excited state of a single P donor in silicon. The relaxation rate of this first excited state to the ground state is estimated to be larger than 2.5 GHz, consistent with theoretical predictions. These results represent a systematic investigation of how an atomically precise single atom transistor device behaves under radio frequency excitations.

  6. Proceedings of the First Landscape State-and-Transition Simulation Modeling Conference, June 14–16, 2011, Portland, Oregon

    Science.gov (United States)

    Becky K. Kerns; Ayn J. Shlisky; Colin J. Daniel

    2012-01-01

    The first ever Landscape State-and-Transition Simulation Modeling Conference was held from June 14–16, 2011, in Portland Oregon. The conference brought together over 70 users of state-and-transition simulation modeling tools—the Vegetation Dynamics Development Tool (VDDT), the Tool for Exploratory Landscape Analysis (TELSA) and the Path Landscape Model. The goal of the...

  7. An explanation for the pseudogap states and the quantum phase transitions beneath the Dome

    Science.gov (United States)

    Cabo, Alejandro Genaro; Vielza, Yoandri; Domingues, Mauricio

    The work present the results of a model proposed to improve the understanding of the normal state of cuprate superconductors. The analysis reproduces the antiferromagnetic correlations and insulator character of these materials. Further, the discussion led to an outstanding prediction: the existence of well defined pseudogap states, which physical origin constitutes still today a debated question. The pseudogap emerges as a paramagnetic excited state, breaking the square crystal symmetry of the CuO planes in the same way as the AF order does it in the real material. The results defined the pseudogap effect as being of pure Coulomb origin. The Fermi surface exhibits the property defining its name: a momentum dependent gap which, that closes at the four corners of the Brillouin cell. The effect of the hole doping on both the AF-Insulator and the pseudogap states was investigated. The evolutions of the energy and band structure with hole doping, became able to predict the quantum phase transition (QPT) which La2CuO4 and other cuprate materials show at doping value, laying ``beneath'' the superconductor ``Dome''. The energies of the insulator and pseudogap states, both tend to coincide at a critical doping value of 0.2, at which the QPT is observed in the material. The doping evolution of the Fermi surface evaluated in for the insulator state, reproduce the experimental results for La2CuO4. We acknoweledge the support received from the Network of the ICTP Net-35.

  8. Modeling and Performance Analysis of State Transitions for Energy-Efficient Femto Base Stations

    Directory of Open Access Journals (Sweden)

    YunWon Chung

    2015-05-01

    Full Text Available Lowering the energy required by base stations (BSs is one of the hot issues nowadays in order to achieve green cellular networks. The energy consumption of femto BSs can be reduced, by turning off the radio interface when there is no mobile station (MS under the coverage area of the femto BSs or MSs served by the femto BSs do not transmit or receive data packets for a long time, especially late at night. In the energy-efficient femto BSs, if MSs have any data packet to transmit and the radio interface of femto BSs is in the off state, MSs wake up the radio interface of femto BSs by using an additional low-power radio interface. In this paper, active (data, idle, active (signaling, sleep entering, sleep and waking up states are defined for the state model for the energy-efficient femto BSs, and the state transitions are modeled analytically. The steady-state probability of each state is derived thoroughly using a semi-Markov approach. Then, the performance of the energy-efficient femto BSs is analyzed in detail, from the aspects of energy consumption, cumulative average delay, cost and low-power radio signaling load. From the results, the tradeoff relationship between energy consumption and cumulative average delay is analyzed in detail, and it was concluded that an appropriate inactivity timer value should be selected to balance the tradeoff.

  9. Diffusion in quasi-one-dimensional channels: A small system n, p, T, transition state theory for hopping times

    Science.gov (United States)

    Ahmadi, Sheida; Bowles, Richard K.

    2017-04-01

    Particles confined to a single file, in a narrow quasi-one-dimensional channel, exhibit a dynamic crossover from single file diffusion to Fickian diffusion as the channel radius increases and the particles begin to pass each other. The long time diffusion coefficient for a system in the crossover regime can be described in terms of a hopping time, which measures the time it takes for a particle to escape the cage formed by its neighbours. In this paper, we develop a transition state theory approach to the calculation of the hopping time, using the small system isobaric-isothermal ensemble to rigorously account for the volume fluctuations associated with the size of the cage. We also describe a Monte Carlo simulation scheme that can be used to calculate the free energy barrier for particle hopping. The theory and simulation method correctly predict the hopping times for a two-dimensional confined ideal gas system and a system of confined hard discs over a range of channel radii, but the method breaks down for wide channels in the hard discs' case, underestimating the height of the hopping barrier due to the neglect of interactions between the small system and its surroundings.

  10. Cell-State Transitions Regulated by SLUG Are Critical for Tissue Regeneration and Tumor Initiation

    Directory of Open Access Journals (Sweden)

    Sarah Phillips

    2014-05-01

    Full Text Available Perturbations in stem cell activity and differentiation can lead to developmental defects and cancer. We use an approach involving a quantitative model of cell-state transitions in vitro to gain insights into how SLUG/SNAI2, a key developmental transcription factor, modulates mammary epithelial stem cell activity and differentiation in vivo. In the absence of SLUG, stem cells fail to transition into basal progenitor cells, while existing basal progenitor cells undergo luminal differentiation; together, these changes result in abnormal mammary architecture and defects in tissue function. Furthermore, we show that in the absence of SLUG, mammary stem cell activity necessary for tissue regeneration and cancer initiation is lost. Mechanistically, SLUG regulates differentiation and cellular plasticity by recruiting the chromatin modifier lysine-specific demethylase 1 (LSD1 to promoters of lineage-specific genes to repress transcription. Together, these results demonstrate that SLUG plays a dual role in repressing luminal epithelial differentiation while unlocking stem cell transitions necessary for tumorigenesis.

  11. Factors Influencing Transitions Between Frailty States in Elderly Adults: The Progetto Veneto Anziani Longitudinal Study.

    Science.gov (United States)

    Trevisan, Caterina; Veronese, Nicola; Maggi, Stefania; Baggio, Giovannella; Toffanello, Elena Debora; Zambon, Sabina; Sartori, Leonardo; Musacchio, Estella; Perissinotto, Egle; Crepaldi, Gaetano; Manzato, Enzo; Sergi, Giuseppe

    2017-01-01

    To investigate frailty state transitions in a cohort of older Italian adults to identify factors exacerbating or improving frailty conditions. Population-based longitudinal study with mean follow-up of 4.4 years. Community. Individuals enrolled in the Progetto Veneto Anziani (Pro.V.A.) (N = 2,925; n = 1,179 male, n = 1,746 female; mean age 74.4 ± 7.3). Frailty was identified at baseline and follow-up based on the presence of at least three Fried criteria; prefrailty was defined as the presence of one or two Fried criteria. Anthropometric, socioeconomic, and clinical characteristics were assessed at baseline in a personal interview and clinical examination using validated scales and medical history. During the study period, 1,114 (38.1%) subjects retained their baseline frailty status, 1,066 (36.4%) had a transition in frailty status, and the remainder of the sample died. Older age, female sex, obesity, cardiovascular disease, osteoarthritis, smoking, loss of vision, low levels of self-sufficiency and physical performance, cognitive impairment, hypovitaminosis D, hyperuricemia, and polypharmacy were associated with increasing frailty and greater mortality. Conversely, overweight, low to moderate drinking, high educational level, and living alone were associated with decreasing frailty. Frailty was confirmed as a dynamic syndrome, with socioeconomic and clinical factors that could be targets of preventive actions influencing transitions to better or worse frailty status. © 2016, Copyright the Authors Journal compilation © 2016, The American Geriatrics Society.

  12. A hard-to-soft state transition of Aquila X-1 observed with Suzaku

    Science.gov (United States)

    Ono, Ko; Makishima, Kazuo; Sakurai, Soki; Zhang, Zhongli; Yamaoka, Kazutaka; Nakazawa, Kazuhiro

    2017-04-01

    The recurrent soft X-ray transient Aquila X-1 was observed with Suzaku for a gross duration of 79.9 ks, on 2011 October 21 when the object was in a rising phase of an outburst. During the observation, the source exhibited a clear spectral transition from the hard state to the soft state, on a time scale of ∼30 ks. Across the transition, the 0.8-10 keV X-Ray Imaging Spectrometer count rate increased by a factor ∼3, that of Hard X-ray Detector PIN (HXD-PIN) in 15-60 keV decreased by a similar factor, and the unabsorbed 0.1-100 keV luminosity increased from 3.5 × 1037 erg s-1 to 5.1 × 1037 erg s-1. The broadband spectral shape changed continuously, from a power-law-like one with a high-energy cut-off to a more convex one. Throughout the transition, the 0.8-60 keV spectra were successfully described with a model consisting of a multi-color blackbody and a Comptonized blackbody, which are considered to arise from a standard accretion disk and a closer vicinity of the neutron star, respectively. All the model parameters were confirmed to change continuously, from those typical in the hard state to those typical of the soft state. More specifically, the inner disk radius decreased from 31 km to 18 km, the effects of Comptonization on the blackbody photons weakened, and the electron temperature of Comptonization decreased from 10 keV to 3 keV. The derived parameters imply that the Comptonizing corona shrinks towards the final soft state, and/or the radial infall velocity of the corona decreases. These results reinforce the view that the soft and hard states of Aql X-1 (and of similar objects) are described by the same “disk plus Comptonized blackbody” model, but with considerably different parameters.

  13. Quantum optics with single quantum dot devices

    International Nuclear Information System (INIS)

    Zwiller, Valery; Aichele, Thomas; Benson, Oliver

    2004-01-01

    A single radiative transition in a single-quantum emitter results in the emission of a single photon. Single quantum dots are single-quantum emitters with all the requirements to generate single photons at visible and near-infrared wavelengths. It is also possible to generate more than single photons with single quantum dots. In this paper we show that single quantum dots can be used to generate non-classical states of light, from single photons to photon triplets. Advanced solid state structures can be fabricated with single quantum dots as their active region. We also show results obtained on devices based on single quantum dots

  14. Saddle-like topological surface states on the T T'X family of compounds (T , T' = Transition metal, X =Si , Ge)

    Science.gov (United States)

    Singh, Bahadur; Zhou, Xiaoting; Lin, Hsin; Bansil, Arun

    2018-02-01

    Topological nodal-line semimetals are exotic conductors that host symmetry-protected conducting nodal lines in their bulk electronic spectrum and nontrivial drumhead states on the surface. Based on first-principles calculations and an effective model analysis, we identify the presence of topological nodal-line semimetal states in the low crystalline symmetric T T'X family of compounds (T ,T' = transition metal, X = Si or Ge) in the absence of spin-orbit coupling (SOC). Taking ZrPtGe as an exemplar system, we show that owing to small lattice symmetry this material harbors a single nodal line on the ky=0 plane with large energy dispersion and unique drumhead surface state with a saddlelike energy dispersion. When the SOC is included, the nodal line gaps out and the system transitions to a strong topological insulator state with Z2=(1 ;000 ) . The topological surface state evolves from the drumhead surface state via the sharing of its saddlelike energy dispersion within the bulk energy gap. These features differ remarkably from those of the currently known topological surface states in topological insulators such as Bi2Se3 with Dirac-cone-like energy dispersions.

  15. The nuclear industry's transition to risk-informed regulation and operation in the United States

    International Nuclear Information System (INIS)

    Kadak, Andrew C.; Matsuo, Toshihiro

    2007-01-01

    This paper summarizes a study of the transition of the United States nuclear industry from a prescriptive regulatory structure to a more risk informed approach to operations and regulations. The transition occurred over a 20 yr period in which gradual changes were made in the fundamental regulations and to the approach to nuclear safety and operations. While the number of actual regulatory changes were few, they are continuing. The utilities that embraced risk informed operations made dramatic changes in the way they approached operations and outage management. Those utilities that used risk in operations showed dramatic improvement in safety based on Institute of Nuclear Power Operations (INPO) performance indicators. It was also shown that the use of risk did not negatively affect safety performance of the plants compared to standard prescriptive approaches. This was despite having greater flexibility in compliance to regulatory standards and the use of the newly instituted risk-informed reactor oversight process. Key factors affecting the successful transition to a more risk-informed approach to regulations and operations are: strong top management support and leadership both at the regulator and the utility; education and training in risk principles and probabilistic risk Assessment tools for engineers, operators and maintenance staff; a slow and steady introduction of risk initiatives in areas that can show value to both the regulator and the industry; a transparent regulatory foundation built around a safety goal policy and the development of a strong safety culture at the utility to allow for more independence in safety compliance and risk management. The experience of the United States shows positive results in both safety and economics. The INPO and NRC metrics presented show that the use of risk information in operations and regulation is marginally better with no degradation in safety when plants that have embraced risk-informed approaches are compared

  16. Single-resonance optical pumping spectroscopy and application in dressed-state measurement with atomic vapor cell at room temperature.

    Science.gov (United States)

    Liang, Qiangbing; Yang, Baodong; Zhang, Tiancai; Wang, Junmin

    2010-06-21

    By monitoring the transmission of probe laser beam (also served as coupling laser beam) which is locked to a cycling hyperfine transition of cesium D(2) line, while pumping laser is scanned across cesium D(1) or D(2) lines, the single-resonance optical pumping (SROP) spectra are obtained with atomic vapor cell. The SROP spectra indicate the variation of the zero-velocity atoms population of one hyperfine fold of ground state, which is optically pumped into another hyperfine fold of ground state by pumping laser. With the virtue of Doppler-free linewidth, high signal-to-noise ratio (SNR), flat background and elimination of crossover resonance lines (CRLs), the SROP spectra with atomic vapor cell around room temperature can be employed to measure dressed-state splitting of ground state, which is normally detected with laser-cooled atomic sample only, even if the dressed-state splitting is much smaller than the Doppler-broaden linewidth at room temperature.

  17. A molecular symmetry analysis of the electronic states and transition dipole moments for molecules with two torsional degrees of freedom

    Energy Technology Data Exchange (ETDEWEB)

    Obaid, R. [Institut für Theoretische Chemie, Universität Wien, Währinger Straße 17, 1090 Vienna (Austria); Applied Chemistry Department, Palestine Polytechnic University, Hebron, Palestine (Country Unknown); Leibscher, M., E-mail: monika.leibscher@itp.uni-hannover.de [Institut für Theoretische Physik, Leibniz Universität Hannover, Appelstr. 2, 30167 Hannover (Germany)

    2015-02-14

    We present a molecular symmetry analysis of electronic states and transition dipole moments for molecules which undergo large amplitude intramolecular torsions. The method is based on the correlation between the point group of the molecule at highly symmetric configurations and the molecular symmetry group. As an example, we determine the global irreducible representations of the electronic states and transition dipole moments for the quinodimethane derivative 2-[4-(cyclopenta-2,4-dien-1-ylidene)cyclohexa-2,5-dien-1-ylidene]-2H-1, 3-dioxole for which two torsional degrees of freedom can be activated upon photo-excitation and construct the resulting symmetry adapted transition dipole functions.

  18. Addressing Single and Multiple Bad Data in the Modern PMU-based Power System State Estimation

    DEFF Research Database (Denmark)

    Khazraj, Hesam; Silva, Filipe Miguel Faria da; Bak, Claus Leth

    2017-01-01

    Detection and analysis of bad data is an important sector of the static state estimation. This paper addresses single and multiple bad data in the modern phasor measurement unit (PMU)-based power system static state estimations. To accomplish this objective, available approaches in the PMU-based ...

  19. DECAY MODES OF HIGH-LYING SINGLE-PARTICLE STATES IN PB-209

    NARCIS (Netherlands)

    BEAUMEL, D; FORTIER, S; GALES, S; GUILLOT, J; LANGEVINJOLIOT, H; LAURENT, H; MAISON, JM; VERNOTTE, J; BORDEWIJK, JA; BRANDENBURG, S; KRASZNAHORKAY, A; CRAWLEY, GM; MASSOLO, CP; RENTERIA, M

    The neutron decay of high-lying single-particle states in Pb-209 excited by means of the (alpha, He-3) reaction has been investigated at 122 MeV incident energy using a multidetector array. The high-spin values of these states, inferred from previous inclusive experiments, are confirmed by the

  20. Discrete-line transitions from superdeformed to yrast states in 194Hg and 192Hg

    International Nuclear Information System (INIS)

    Hackman, G.; Khoo, T.L.; Ackermann, D.

    1996-01-01

    Discrete-line γ-ray decay from superdeformed (SD) to yrast states in 194,192 Hg has been studied with the Gammasphere spectrometer. The previously established decay for the yrast SD band of 194 Hg has been characterized further. In addition, one-step decays have been observed for 194 Hg SD band 3, which fixes the excitation energy and spin of the last observed level of this band at E* = 7.455 MeV, J = 11ℎ. So far no direct decays from superdeformed to yrast states have been observed in 192 Hg or in 194 Hg band 2, a result which is consistent with fluctuations of the transition strengths

  1. Probing the transition state region in catalytic CO oxidation on Ru

    Energy Technology Data Exchange (ETDEWEB)

    Ostrom, H. [Stockholm Univ. (Sweden); Oberg, H. [Stockholm Univ. (Sweden); Xin, H. [SLAC National Accelerator Lab., Menlo Park, CA (United States); LaRue, J. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States); Beye, M. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Helmholtz Zentrum Berlin fur Materialien und Energie GmbH, Berlin (Germany); Dell' Angela, M. [Univ. of Hamburg and Center for Free Electron Laser Science, Hamburg (Germany); Gladh, J. [Stockholm Univ. (Sweden); Ng, M. L. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Sellberg, J. A. [Stockholm Univ. (Sweden); SLAC National Accelerator Lab., Menlo Park, CA (United States); Kaya, S. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Mercurio, G. [Univ. of Hamburg and Center for Free Electron Laser Science, Hamburg (Germany); Nordlund, D. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Hantschmann, M. [Helmholtz Zentrum Berlin fur Materialien und Energie GmbH, Berlin (Germany); Hieke, F. [Univ. of Hamburg and Center for Free Electron Laser Science, Hamburg (Germany); Kuhn, D. [Helmholtz Zentrum Berlin fur Materialien und Energie GmbH, Berlin (Germany); Schlotter, W. F. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Dakovski, G. L. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Turner, J. J. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Minitti, M. P. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Mitra, A. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Moeller, S. P. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Fohlisch, A. [Helmholtz Zentrum Berlin fur Materialien und Energie GmbH, Berlin (Germany); Univ. Potsdam, Potsdam (Germany); Wolf, M. [Fritz-Haber Institute of the Max-Planck-Society, Berlin (Germany); Wurth, W. [Univ. of Hamburg and Center for Free Electron Laser Science, Hamburg (Germany); DESY Photon Science, Hamburg (Germany); Persson, M. [The Univ. of Liverpool, Liverpool (United Kingdom); Norskov, J. K. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States); Abild-Pedersen, F. [Stanford Univ., Stanford, CA (United States); Ogasawara, H. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Pettersson, L. G. M. [Stockholm Univ. (Sweden); Nilsson, A. [Stockholm Univ. (Sweden); SLAC National Accelerator Lab., Menlo Park, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-02-12

    Femtosecond x-ray laser pulses are used to probe the CO oxidation reaction on ruthenium (Ru) initiated by an optical laser pulse. On a time scale of a few hundred femtoseconds, the optical laser pulse excites motions of CO and O on the surface, allowing the reactants to collide, and, with a transient close to a picosecond (ps), new electronic states appear in the O K-edge x-ray absorption spectrum. Density functional theory calculations indicate that these result from changes in the adsorption site and bond formation between CO and O with a distribution of OC–O bond lengths close to the transition state (TS). After 1 ps, 10% of the CO populate the TS region, which is consistent with predictions based on a quantum oscillator model.

  2. Growth of single crystals of BaFe12O19 by solid state crystal growth

    International Nuclear Information System (INIS)

    Fisher, John G.; Sun, Hengyang; Kook, Young-Geun; Kim, Joon-Seong; Le, Phan Gia

    2016-01-01

    Single crystals of BaFe 12 O 19 are grown for the first time by solid state crystal growth. Seed crystals of BaFe 12 O 19 are buried in BaFe 12 O 19 +1 wt% BaCO 3 powder, which are then pressed into pellets containing the seed crystals. During sintering, single crystals of BaFe 12 O 19 up to ∼130 μm thick in the c-axis direction grow on the seed crystals by consuming grains from the surrounding polycrystalline matrix. Scanning electron microscopy-energy dispersive spectroscopy analysis shows that the single crystal and the surrounding polycrystalline matrix have the same chemical composition. Micro-Raman scattering shows the single crystal to have the BaFe 12 O 19 structure. The optimum growth temperature is found to be 1200 °C. The single crystal growth behavior is explained using the mixed control theory of grain growth. - Highlights: • Single crystals of BaFe 12 O 19 are grown by solid state crystal growth. • A single crystal up to ∼130 μm thick (c-axis direction) grows on the seed crystal. • The single crystal and surrounding ceramic matrix have similar composition. • Micro-Raman scattering shows the single crystal has the BaFe 12 O 19 structure.

  3. Single transition metal atom embedded into a MoS2nanosheet as a promising catalyst for electrochemical ammonia synthesis.

    Science.gov (United States)

    Zhao, Jia; Zhao, Jingxiang; Cai, Qinghai

    2018-03-21

    The electrochemical reduction of N2 to NH3 (NRR) under ambient conditions is significant for sustainable agriculture. Here, by means of density functional theory (DFT) computations, the potential of a series of single transition metal (TM) atoms embedded into a MoS2 monolayer with an S-vacancy (TM/MoS2) as electrocatalysts for NRR was systematically investigated. Our DFT results revealed that among all these considered candidate catalysts, the single Mo atom embedded into the MoS2 nanosheet was found to be the most active catalyst for NRR with an onset potential of -0.53 V, in which the hydrogenation of the adsorbed N2* to N2H* is the potential-determining step. The high stabilization of the N2H* species is responsible for the superior performance of the embedded Mo atom for the NRR, which is well consistent with its d-band center. Our findings may facilitate the further design of single-atom electrocatalysts with high efficiency for NH3 synthesis at room temperature.

  4. The peptide-receptive transition state of MHC-1 molecules: Insight from structure and molecular dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Robinson H.; Mage, M.; Dolan, M.; Wang, R.; Boyd, L.; Revilleza, M.; Natarajan, K.; Myers, N.; Hansen, T.; Margulies, D.

    2012-05-01

    MHC class I (MHC-I) proteins of the adaptive immune system require antigenic peptides for maintenance of mature conformation and immune function via specific recognition by MHC-I-restricted CD8(+) T lymphocytes. New MHC-I molecules in the endoplasmic reticulum are held by chaperones in a peptide-receptive (PR) transition state pending release by tightly binding peptides. In this study, we show, by crystallographic, docking, and molecular dynamics methods, dramatic movement of a hinged unit containing a conserved 3(10) helix that flips from an exposed 'open' position in the PR transition state to a 'closed' position with buried hydrophobic side chains in the peptide-loaded mature molecule. Crystallography of hinged unit residues 46-53 of murine H-2L(d) MHC-I H chain, complexed with mAb 64-3-7, demonstrates solvent exposure of these residues in the PR conformation. Docking and molecular dynamics predict how this segment moves to help form the A and B pockets crucial for the tight peptide binding needed for stability of the mature peptide-loaded conformation, chaperone dissociation, and Ag presentation.

  5. Flexible transition state theory for a variable reaction coordinate: Derivation of canonical and microcanonical forms

    International Nuclear Information System (INIS)

    Robertson, Struan; Wagner, Albert F.; Wardlaw, David M.

    2000-01-01

    A completely general canonical and microcanonical (energy-resolved) flexible transition state theory (FTST) expression for the rate constant is derived for an arbitrary choice of reaction coordinate. The derivation is thorough and rigorous within the framework of FTST and replaces our previous treatments [Robertson et al., J. Chem. Phys. 103, 2917 (1995); Robertson et al., Faraday Discuss. Chem. Soc. 102, 65 (1995)] which implicitly involved some significant assumptions. The canonical rate expressions obtained here agree with our earlier results. The corresponding microcanonical results are new. The rate expressions apply to any definition of the separation distance between fragments in a barrierless recombination (or dissociation) that is held fixed during hindered rotations at the transition state, and to any combination of fragment structure (atom, linear top, nonlinear top). The minimization of the rate constant with respect to this definition can be regarded as optimizing the reaction coordinate within a canonical or microcanonical framework. The expression is analytic except for a configuration integral whose evaluation generally requires numerical integration over internal angles (from one to five depending on the fragment structures). The form of the integrand in this integral has important conceptual and computational implications. The primary component of the integrand is the determinant of the inverse G-matrix associated with the external rotations and the relative internal motion of the fragments. (c) 2000 American Institute of Physics

  6. A structural analysis of the A5/1 state transition graph

    Directory of Open Access Journals (Sweden)

    Andreas Beckmann

    2012-10-01

    Full Text Available We describe efficient algorithms to analyze the cycle structure of the graph induced by the state transition function of the A5/1 stream cipher used in GSM mobile phones and report on the results of the implementation. The analysis is performed in five steps utilizing HPC clusters, GPGPU and external memory computation. A great reduction of this huge state transition graph of 2^64 nodes is achieved by focusing on special nodes in the first step and removing leaf nodes that can be detected with limited effort in the second step. This step does not break the overall structure of the graph and keeps at least one node on every cycle. In the third step the nodes of the reduced graph are connected by weighted edges. Since the number of nodes is still huge an efficient bitslice approach is presented that is implemented with NVIDIA's CUDA framework and executed on several GPUs concurrently. An external memory algorithm based on the STXXL library and its parallel pipelining feature further reduces the graph in the fourth step. The result is a graph containing only cycles that can be further analyzed in internal memory to count the number and size of the cycles. This full analysis which previously would take months can now be completed within a few days and allows to present structural results for the full graph for the first time. The structure of the A5/1 graph deviates notably from the theoretical results for random mappings.

  7. Crossing the dividing surface of transition state theory. III. Once and only once. Selecting reactive trajectories

    Energy Technology Data Exchange (ETDEWEB)

    Lorquet, J. C., E-mail: jc.lorquet@ulg.ac.be [Department of Chemistry, University of Liège, Sart-Tilman (Bâtiment B6), B-4000 Liège 1 (Belgium)

    2015-09-14

    The purpose of the present work is to determine initial conditions that generate reacting, recrossing-free trajectories that cross the conventional dividing surface of transition state theory (i.e., the plane in configuration space passing through a saddle point of the potential energy surface and perpendicular to the reaction coordinate) without ever returning to it. Local analytical equations of motion valid in the neighborhood of this planar surface have been derived as an expansion in Poisson brackets. We show that the mere presence of a saddle point implies that reactivity criteria can be quite simply formulated in terms of elements of this series, irrespective of the shape of the potential energy function. Some of these elements are demonstrated to be equal to a sum of squares and thus to be necessarily positive, which has a profound impact on the dynamics. The method is then applied to a three-dimensional model describing an atom-diatom interaction. A particular relation between initial conditions is shown to generate a bundle of reactive trajectories that form reactive cylinders (or conduits) in phase space. This relation considerably reduces the phase space volume of initial conditions that generate recrossing-free trajectories. Loci in phase space of reactive initial conditions are presented. Reactivity is influenced by symmetry, as shown by a comparative study of collinear and bent transition states. Finally, it is argued that the rules that have been derived to generate reactive trajectories in classical mechanics are also useful to build up a reactive wave packet.

  8. Efficient Sampling of the Structure of Crypto Generators' State Transition Graphs

    Science.gov (United States)

    Keller, Jörg

    Cryptographic generators, e.g. stream cipher generators like the A5/1 used in GSM networks or pseudo-random number generators, are widely used in cryptographic network protocols. Basically, they are finite state machines with deterministic transition functions. Their state transition graphs typically cannot be analyzed analytically, nor can they be explored completely because of their size which typically is at least n = 264. Yet, their structure, i.e. number and sizes of weakly connected components, is of interest because a structure deviating significantly from expected values for random graphs may form a distinguishing attack that indicates a weakness or backdoor. By sampling, one randomly chooses k nodes, derives their distribution onto connected components by graph exploration, and extrapolates these results to the complete graph. In known algorithms, the computational cost to determine the component for one randomly chosen node is up to O(√n), which severely restricts the sample size k. We present an algorithm where the computational cost to find the connected component for one randomly chosen node is O(1), so that a much larger sample size k can be analyzed in a given time. We report on the performance of a prototype implementation, and about preliminary analysis for several generators.

  9. Post-transition state dynamics and product energy partitioning following thermal excitation of the F⋯HCH2CN transition state: Disagreement with experiment.

    Science.gov (United States)

    Pratihar, Subha; Ma, Xinyou; Xie, Jing; Scott, Rebecca; Gao, Eric; Ruscic, Branko; Aquino, Adelia J A; Setser, Donald W; Hase, William L

    2017-10-14

    Born-Oppenheimer direct dynamics simulations were performed to study atomistic details of the F + CH 3 CN → HF + CH 2 CN H-atom abstraction reaction. The simulation trajectories were calculated with a combined M06-2X/MP2 algorithm utilizing the 6-311++G** basis set. The experiments were performed at 300 K, and assuming the accuracy of transition state theory (TST), the trajectories were initiated at the F⋯HCH 2 CN abstraction TS with a 300 K Boltzmann distribution of energy and directed towards products. Recrossing of the TS was negligible, confirming the accuracy of TST. HF formation was rapid, occurring within 0.014 ps of the trajectory initiation. The intrinsic reaction coordinate (IRC) for reaction involves rotation of HF about CH 2 CN and then trapping in the CH 2 CN⋯HF post-reaction potential energy well of ∼10 kcal/mol with respect to the HF + CH 2 CN products. In contrast to this IRC, five different trajectory types were observed: the majority proceeded by direct H-atom transfer and only 11% approximately following the IRC. The HF vibrational and rotational quantum numbers, n and J, were calculated when HF was initially formed and they increase as potential energy is released in forming the HF + CH 2 CN products. The population of the HF product vibrational states is only in qualitative agreement with experiment, with the simulations showing depressed and enhanced populations of the n = 1 and 2 states as compared to experiment. Simulations with an anharmonic zero-point energy constraint gave product distributions for relative translation, HF rotation, HF vibration, CH 2 CN rotation, and CH 2 CN vibration as 5%, 11%, 60%, 7%, and 16%, respectively. In contrast, the experimental energy partitioning percentages to HF rotation and vibration are 6% and 41%. Comparisons are made between the current simulation and those for other F + H-atom abstraction reactions. The simulation product energy partitioning and HF vibrational population for F + CH 3 CN

  10. High-fidelity teleportation of continuous-variable quantum States using delocalized single photons

    DEFF Research Database (Denmark)

    Andersen, Ulrik L; Ralph, Timothy C

    2013-01-01

    Traditional continuous-variable teleportation can only approach unit fidelity in the limit of an infinite (and unphysical) amount of squeezing. We describe a new method for continuous-variable teleportation that approaches unit fidelity with finite resources. The protocol is not based on squeezed...... states as in traditional teleportation but on an ensemble of single photon entangled states. We characterize the teleportation scheme with coherent states, mesoscopic superposition states, and two-mode squeezed states and we find several situations in which near-unity teleportation fidelity can...

  11. Before the endless forms: embodied model of transition from single cells to aggregates to ecosystem engineering.

    Directory of Open Access Journals (Sweden)

    Ricard V Solé

    Full Text Available The emergence of complex multicellular systems and their associated developmental programs is one of the major problems of evolutionary biology. The advantages of cooperation over individuality seem well known but it is not clear yet how such increase of complexity emerged from unicellular life forms. Current multicellular systems display a complex cell-cell communication machinery, often tied to large-scale controls of body size or tissue homeostasis. Some unicellular life forms are simpler and involve groups of cells cooperating in a tissue-like fashion, as it occurs with biofilms. However, before true gene regulatory interactions were widespread and allowed for controlled changes in cell phenotypes, simple cellular colonies displaying adhesion and interacting with their environments were in place. In this context, models often ignore the physical embedding of evolving cells, thus leaving aside a key component. The potential for evolving pre-developmental patterns is a relevant issue: how far a colony of evolving cells can go? Here we study these pre-conditions for morphogenesis by using CHIMERA, a physically embodied computational model of evolving virtual organisms in a pre-Mendelian world. Starting from a population of identical, independent cells moving in a fluid, the system undergoes a series of changes, from spatial segregation, increased adhesion and the development of generalism. Eventually, a major transition occurs where a change in the flow of nutrients is triggered by a sub-population. This ecosystem engineering phenomenon leads to a subsequent separation of the ecological network into two well defined compartments. The relevance of these results for evodevo and its potential ecological triggers is discussed.

  12. Identifying the transition between single and multiple mating of queens in fungus-growing ants

    DEFF Research Database (Denmark)

    Villesen, Palle; Murakami, Takahiro; Schultz, Ted R

    2002-01-01

    Obligate mating of females (queens) with multiple males has evolved only rarely in social Hymenoptera (ants, social bees, social wasps) and for reasons that are fundamentally different from those underlying multiple mating in other animals. The monophyletic tribe of ('attine') fungus-growing ants...... is known to include evolutionarily derived genera with obligate multiple mating (the Acromyrmex and Atta leafcutter ants) as well as phylogenetically basal genera with exclusively single mating (e.g. Apterostigma, Cyphomyrmex, Myrmicocrypta). All attine genera share the unique characteristic of obligate...... dependence on symbiotic fungus gardens for food, but the sophistication of this symbiosis differs considerably across genera. The lower attine genera generally have small, short-lived colonies and relatively non-specialized fungal symbionts (capable of living independently of their ant hosts), whereas...

  13. Counting efficiencies by liquid scintillation counting. Single isomeric transitions; Eficiencia de recuento por centelleo liquido. Transiciones isomericas simples

    Energy Technology Data Exchange (ETDEWEB)

    Grau Carles, A.; Grau Malonda, A.

    1995-07-01

    In this work we present liquid scintillation counting efficiency tables for several radionuclides with single isomeric transitions, in which electron conversion and gamma emission processes are competitive. We study the radionuclides: 58mCo, 77mSe, 79mBr, 87mSr, S9mY, 93mNb, 103mRh, 107mAg, 109mAg, 113mIn, 131mXe, I33mXe, 135raBa, 137mBa, 167raEr, for two different scintillators, Ultima-Gold and Insta-Gel. We consider volumes of 10 and 15 mL for Ultima Gold, and 15 mL for Insta-Gel. (Author) 18 refs.

  14. Phase transitions and optical properties of the semiconducting and metallic phases of single-layer MoS₂.

    Science.gov (United States)

    Fair, K M; Ford, M J

    2015-10-30

    We report density functional theory calculations for single layer MoS2 in its 2H, semiconducting and 1T metallic phases in order to understand the relative stability of these two phases and transition between them in the presence of adsorbed lithium atoms and under compressive strain. We have determined the diffusion barriers between the two phases and demonstrate how the presence of Li adatoms or strain can significantly reduce these barriers. We show that the 2H and 1T structures have the same energy under 15% biaxial, compressive strain. This is the same strain value posited by Lin et al (2014 Nat. Nanotechnology 9 391-396) for their intermediate α phase. Calculations of the 1T and 2H permittivity and electron energy loss spectrum are also performed and characterized.

  15. Single crystal growth and structural evolution across the 1st order valence transition in (Pr1-yYy)1-xCaxCoO3-δ

    Science.gov (United States)

    Schreiber, N. J.; Zhang, Junjie; Zheng, Hong; Freeland, J. W.; Chen, Yu-Sheng; Mitchell, J. F.; Phelan, D.

    2017-10-01

    Praseodymium-containing cobalt perovskites, such as (Pr1-yYy)1-xCaxCoO3-δ, have been argued to undergo a first-order charge shift between Pr and hybridized Co-O orbitals that leads to a metal-insulator transition at a temperature, TVT. Magnetization and x-ray absorption spectroscopy measurements on single crystals of (Pr0.85Y0.15)0.7Ca0.3CoO3-δ grown in an IR image furnace under 40-60 bar of oxygen confirm the presence of this valence transition. Single crystal x-ray synchrotron diffraction measurements are consistent with an isomorphic phase transition at TVT. No evidence of charge ordering was revealed by the single crystal diffraction. Dissimilar to analytical transmission electron microscopy measurements performed on a grain from a polycrystalline sample that revealed an oxygen vacancy order-disorder transition at TVT, the present single-crystal measurements did not evidence such a transition, likely reflecting a lower density of oxygen vacancies in the high-pO2 grown single crystals.

  16. Solid-state molecular organometallic chemistry. Single-crystal to single-crystal reactivity and catalysis with light hydrocarbon substrates.

    Science.gov (United States)

    Chadwick, F Mark; McKay, Alasdair I; Martinez-Martinez, Antonio J; Rees, Nicholas H; Krämer, Tobias; Macgregor, Stuart A; Weller, Andrew S

    2017-08-01

    Single-crystal to single-crystal solid/gas reactivity and catalysis starting from the precursor sigma-alkane complex [Rh(Cy 2 PCH 2 CH 2 PCy 2 )(η 2 η 2 -NBA)][BAr F 4 ] (NBA = norbornane; Ar F = 3,5-(CF 3 ) 2 C 6 H 3 ) is reported. By adding ethene, propene and 1-butene to this precursor in solid/gas reactions the resulting alkene complexes [Rh(Cy 2 PCH 2 CH 2 PCy 2 )(alkene) x ][BAr F 4 ] are formed. The ethene ( x = 2) complex, [Rh(Cy 2 PCH 2 CH 2 PCy 2 )(ethene) 2 ][BAr F 4 ]-Oct , has been characterized in the solid-state (single-crystal X-ray diffraction) and by solution and solid-state NMR spectroscopy. Rapid, low temperature recrystallization using solution methods results in a different crystalline modification, [Rh(Cy 2 PCH 2 CH 2 PCy 2 )(ethene) 2 ][BAr F 4 ]-Hex , that has a hexagonal microporous structure ( P 6 3 22). The propene complex ( x = 1) [Rh(Cy 2 PCH 2 CH 2 PCy 2 )(propene)][BAr F 4 ] is characterized as having a π-bound alkene with a supporting γ-agostic Rh···H 3 C interaction at low temperature by single-crystal X-ray diffraction, variable temperature solution and solid-state NMR spectroscopy, as well as periodic density functional theory (DFT) calculations. A fluxional process occurs in both the solid-state and solution that is proposed to proceed via a tautomeric allyl-hydride. Gas/solid catalytic isomerization of d 3 -propene, H 2 C 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111

  17. GRHL3 binding and enhancers rearrange as epidermal keratinocytes transition between functional states.

    Directory of Open Access Journals (Sweden)

    Rachel Herndon Klein

    2017-04-01

    Full Text Available Transcription factor binding, chromatin modifications and large scale chromatin re-organization underlie progressive, irreversible cell lineage commitments and differentiation. We know little, however, about chromatin changes as cells enter transient, reversible states such as migration. Here we demonstrate that when human progenitor keratinocytes either differentiate or migrate they form complements of typical enhancers and super-enhancers that are unique for each state. Unique super-enhancers for each cellular state link to gene expression that confers functions associated with the respective cell state. These super-enhancers are also enriched for skin disease sequence variants. GRHL3, a transcription factor that promotes both differentiation and migration, binds preferentially to super-enhancers in differentiating keratinocytes, while during migration, it binds preferentially to promoters along with REST, repressing the expression of migration inhibitors. Key epidermal differentiation transcription factor genes, including GRHL3, are located within super-enhancers, and many of these transcription factors in turn bind to and regulate super-enhancers. Furthermore, GRHL3 represses the formation of a number of progenitor and non-keratinocyte super-enhancers in differentiating keratinocytes. Hence, chromatin relocates GRHL3 binding and enhancers to regulate both the irreversible commitment of progenitor keratinocytes to differentiation and their reversible transition to migration.

  18. Cotunneling spectroscopy and the properties of excited-state spin manifolds of Mn12 single molecule magnets

    Science.gov (United States)

    Rostamzadeh Renani, Fatemeh; Kirczenow, George

    2014-10-01

    We study charge transport through single molecule magnet (SMM) junctions in the cotunneling regime as a tool for investigating the properties of the excited-state manifolds of neutral Mn12 SMs. This study is motivated by a recent transport experiment [S. Kahle et al., Nano Lett. 12, 518 (2012), 10.1021/nl204141z] that probed the details of the magnetic and electronic structure of Mn12 SMMs beyond the ground-state spin manifold. A giant spin Hamiltonian and master equation approach is used to explore theoretically the cotunneling transport through Mn12-Ac SMM junctions. We identify SMM transitions that can account for both the strong and weak features of the experimental differential conductance spectra. We find the experimental results to imply that the excited spin-state manifolds of the neutral SMM have either different anisotropy constants or different g factors in comparison with its ground-state manifold. However, the latter scenario accounts best for the experimental data.

  19. Effects of a Transition to a Hydrogen Economy on Employment in the United States

    Energy Technology Data Exchange (ETDEWEB)

    Tolley, George S.; Jones, Donald W. Mintz, Marianne M.; Smith, Barton A.; Carlson, Eric; Unnasch, Stefan; Lawrence, Michael; Chmelynski, Harry

    2008-07-01

    The U.S. Department of Energy report, Effects of a Transition to a Hydrogen Economy on Employment in the United States Report to Congress, estimates the effects on employment of a U.S. economy transformation to hydrogen between 2020 and 2050. The report includes study results on employment impacts from hydrogen market expansion in the transportation, stationary, and portable power sectors and highlights possible skill and education needs. This study is in response to Section 1820 of the Energy Policy Act of 2005 (Public Law 109-58) (EPACT). Section 1820, “Overall Employment in a Hydrogen Economy,” requires the Secretary of Energy to carry out a study of the effects of a transition to a hydrogen economy on several employment [types] in the United States. As required by Section 1820, the present report considers: • Replacement effects of new goods and services • International competition • Workforce training requirements • Multiple possible fuel cycles, including usage of raw materials • Rates of market penetration of technologies • Regional variations based on geography • Specific recommendations of the study Both the Administration’s National Energy Policy and the Department’s Strategic Plan call for reducing U.S. reliance on imported oil and reducing greenhouse gas emissions. The National Energy Policy also acknowledges the need to increase energy supplies and use more energy-efficient technologies and practices. President Bush proposed in his January 2003 State of the Union Address to advance research on hydrogen so that it has the potential to play a major role in America’s future energy system. Consistent with these aims, EPACT 2005 authorizes a research, development, and demonstration program for hydrogen and fuel cell technology. Projected results for the national employment impacts, projections of the job creation and job replacement underlying the total employment changes, training implications, regional employment impacts and the

  20. Effects of a Transition to a Hydrogen Economy on Employment in the United States

    International Nuclear Information System (INIS)

    Tolley, George S.; Jones, Donald W.; Mintz, Marianne M.; Smith, Barton A.; Carlson, Eric; Unnasch, Stefan; Lawrence, Michael; Chmelynski, Harry

    2008-01-01

    The U.S. Department of Energy report, Effects of a Transition to a Hydrogen Economy on Employment in the United States Report to Congress, estimates the effects on employment of a U.S. economy transformation to hydrogen between 2020 and 2050. The report includes study results on employment impacts from hydrogen market expansion in the transportation, stationary, and portable power sectors and highlights possible skill and education needs. This study is in response to Section 1820 of the Energy Policy Act of 2005 (Public Law 109-58) (EPACT). Section 1820, 'Overall Employment in a Hydrogen Economy', requires the Secretary of Energy to carry out a study of the effects of a transition to a hydrogen economy on several employment (types) in the United States. As required by Section 1820, the present report considers: (1) Replacement effects of new goods and services; (2) International competition; (3) Workforce training requirements; (4) Multiple possible fuel cycles, including usage of raw materials; (5) Rates of market penetration of technologies; (6) Regional variations based on geography; and (7) Specific recommendations of the study Both the Administration's National Energy Policy and the Department's Strategic Plan call for reducing U.S. reliance on imported oil and reducing greenhouse gas emissions. The National Energy Policy also acknowledges the need to increase energy supplies and use more energy-efficient technologies and practices. President Bush proposed in his January 2003 State of the Union Address to advance research on hydrogen so that it has the potential to play a major role in America's future energy system. Consistent with these aims, EPACT 2005 authorizes a research, development, and demonstration program for hydrogen and fuel cell technology. Projected results for the national employment impacts, projections of the job creation and job replacement underlying the total employment changes, training implications, regional employment impacts and the

  1. Electrostatic transition state stabilization rather than reactant destabilization provides the chemical basis for efficient chorismate mutase catalysis.

    Science.gov (United States)

    Burschowsky, Daniel; van Eerde, André; Ökvist, Mats; Kienhöfer, Alexander; Kast, Peter; Hilvert, Donald; Krengel, Ute

    2014-12-09

    For more than half a century, transition state theory has provided a useful framework for understanding the origins of enzyme catalysis. As proposed by Pauling, enzymes accelerate chemical reactions by binding transition states tighter than substrates, thereby lowering the activation energy compared with that of the corresponding uncatalyzed process. This paradigm has been challenged for chorismate mutase (CM), a well-characterized metabolic enzyme that catalyzes the rearrangement of chorismate to prephenate. Calculations have predicted the decisive factor in CM catalysis to be ground state destabilization rather than transition state stabilization. Using X-ray crystallography, we show, in contrast, that a sluggish variant of Bacillus subtilis CM, in which a cationic active-site arginine was replaced by a neutral citrulline, is a poor catalyst even though it effectively preorganizes chorismate for the reaction. A series of high-resolution molecular snapshots of the reaction coordinate, including the apo enzyme, and complexes with substrate, transition state analog and product, demonstrate that an active site, which is only complementary in shape to a reactive substrate conformer, is insufficient for effective catalysis. Instead, as with other enzymes, electrostatic stabilization of the CM transition state appears to be crucial for achieving high reaction rates.

  2. Accounting for conformational flexibility and torsional anharmonicity in the H + CH3CH2OH hydrogen abstraction reactions: a multi-path variational transition state theory study.

    Science.gov (United States)

    Meana-Pañeda, Rubén; Fernández-Ramos, Antonio

    2014-05-07

    This work reports a detailed theoretical study of the hydrogen abstraction reactions from ethanol by atomic hydrogen. The calculated thermal rate constants take into account torsional anharmonicity and conformational flexibility, in addition to the variational and tunneling effects. Specifically, the kinetics calculations were performed by using multi-path canonical variational transition state theory with least-action path tunneling corrections, to which we have added the two-dimensional non-separable method to take into account torsional anharmonicity. The multi-path thermal rate constant is expressed as a sum over conformational reaction channels. Each of these channels includes all the transition states that can be reached by internal rotations. The results show that, in the interval of temperatures between 250 and 2500 K, the account for multiple paths leads to higher thermal rate constants with respect to the single path approach, mainly at low and at high temperatures. In addition, torsional anharmonicity enhances the slope of the Arrhenius plot in this range of temperatures. Finally, we show that the incorporation of tunneling into the hydrogen abstraction reactions substantially changes the contribution of each of the transition states to the conformational reaction channel.

  3. First-principles studies of BN sheets with absorbed transition metal single atoms or dimers: stabilities, electronic structures, and magnetic properties.

    Science.gov (United States)

    Ma, Dongwei; Lu, Zhansheng; Ju, Weiwei; Tang, Yanan

    2012-04-11

    BN sheets with absorbed transition metal (TM) single atoms, including Fe, Co, and Ni, and their dimers have been investigated by using a first-principles method within the generalized gradient approximation. All of the TM atoms studied are found to be chemically adsorbed on BN sheets. Upon adsorption, the binding energies of the Fe and Co single atoms are modest and almost independent of the adsorption sites, indicating the high mobility of the adatoms and isolated particles to be easily formed on the surface. However, Ni atoms are found to bind tightly to BN sheets and may adopt a layer-by-layer growth mode. The Fe, Co, and Ni dimers tend to lie (nearly) perpendicular to the BN plane. Due to the wide band gap of the pure BN sheet, the electronic structures of the BN sheets with TM adatoms are determined primarily by the distribution of TM electronic states around the Fermi level. Very interesting spin gapless semiconductors or half-metals can be obtained in the studied systems. The magnetism of the TM atoms is preserved well on the BN sheet, very close to that of the corresponding free atoms and often weakly dependent on the adsorption sites. The present results indicate that BN sheets with adsorbed TM atoms have potential applications in fields such as spintronics and magnetic data storage due to the special spin-polarized electronic structures and magnetic properties they possess.

  4. Single-parent households and children's educational achievement: A state-level analysis.

    Science.gov (United States)

    Amato, Paul R; Patterson, Sarah; Beattie, Brett

    2015-09-01

    Although many studies have examined associations between family structure and children's educational achievement at the individual level, few studies have considered how the increase in single-parent households may have affected children's educational achievement at the population level. We examined changes in the percentage of children living with single parents between 1990 and 2011 and state mathematics and reading scores on the National Assessment of Educational Progress. Regression models with state and year fixed effects revealed that changes in the percentage of children living with single parents were not associated with test scores. Increases in maternal education, however, were associated with improvements in children's test scores during this period. These results do not support the notion that increases in single parenthood have had serious consequences for U.S. children's school achievement. Copyright © 2015 Elsevier Inc. All rights reserved.

  5. Storing single photons emitted by a quantum memory on a highly excited Rydberg state.

    Science.gov (United States)

    Distante, Emanuele; Farrera, Pau; Padrón-Brito, Auxiliadora; Paredes-Barato, David; Heinze, Georg; de Riedmatten, Hugues

    2017-01-19

    Strong interaction between two single photons is a long standing and important goal in quantum photonics. This would enable a new regime of nonlinear optics and unlock several applications in quantum information science, including photonic quantum gates and deterministic Bell-state measurements. In the context of quantum networks, it would be important to achieve interactions between single photons from independent photon pairs storable in quantum memories. So far, most experiments showing nonlinearities at the single-photon level have used weak classical input light. Here we demonstrate the storage and retrieval of a paired single photon emitted by an ensemble quantum memory in a strongly nonlinear medium based on highly excited Rydberg atoms. We show that nonclassical correlations between the two photons persist after retrieval from the Rydberg ensemble. Our result is an important step towards deterministic photon-photon interactions, and may enable deterministic Bell-state measurements with multimode quantum memories.

  6. Hierarchically controlled remote preparation of an arbitrary single-qubit state by using a four-qubit |χ > entangled state

    Science.gov (United States)

    Ma, Peng-Cheng; Chen, Gui-Bin; Li, Xiao-Wei; Zhan, You-Bang

    2018-05-01

    In this paper, we present a scheme for Hierarchically controlled remote preparation of an arbitrary single-qubit state via a four-qubit |χ > state as the quantum channel. In this scheme, a sender wishes to help three agents to remotely prepare a quantum state, respectively. The three agents are divided into two grades, that is, an agent is in the upper grade and other two agents are in the lower grade. It is shown that the agent of the upper grade only needs the assistance of any one of the other two agents for recovering the sender's original state, while an agent of the lower grade needs the collaboration of all the other two agents. In other words, the agents of two grades have different authorities to recover sender's original state.

  7. Transition of Femtosecond-Filament-Solid Interactions from Single to Multiple Filament Regime.

    Science.gov (United States)

    Skrodzki, P J; Burger, M; Jovanovic, I

    2017-10-06

    High-peak-power fs-laser filaments offer unique characteristics attractive to remote sensing via techniques such as remote laser-induced breakdown spectroscopy (R-LIBS). The dynamics of several ablation mechanisms following the interaction between a filament and a solid determines the emission strength and reproducibility of target plasma, which is of relevance for R-LIBS applications. We investigate the space- and time-resolved dynamics of ionic and atomic emission from copper as well as the surrounding atmosphere in order to understand limitations of fs-filament-ablation for standoff energy delivery. Furthermore, we probe the shock front produced from filament-target interaction using time-resolved shadowgraphy and infer laser-material coupling efficiencies for both single and multiple filament regimes through analysis of shock expansion with the Sedov model for point detonation. The results provide insight into plasma structure for the range of peak powers up to 30 times the critical power for filamentation P cr . Despite the stochastic nucleation of multiple filaments at peak-powers greater than 16 P cr , emission of ionic and neutral species increases with pump beam intensity, and short-lived nitrogen emission originating from the ambient is consistently observed. Ultimately, results suggest favorable scaling of emission intensity from target species on the laser pump energy, furthering the prospects for use of filament-solid interactions for remote sensing.

  8. The B(E2) value of the first-excited to ground-state transition in 49Ti

    International Nuclear Information System (INIS)

    Mando, P.A.; Sona, P.; Taccetti, N.; Liberati, G.

    1978-01-01

    The B(E2) value of the 1381 keV transition connecting the J=3/2 - first excited state to the J=7/2 - ground state in 49 Ti has been determined by means of Coulomb excitation measurements. The value obtained is B(E2)=(33.5+- 4.5) e 2 fm 4

  9. State and transition models: Theory, applications, and challenges. In: Briske, D.D. Rangeland Systems: Processes, Management and Challenges

    Science.gov (United States)

    State and transition models (STMs) are used for communicating about ecosystem change in rangelands and other ecosystems, especially the implications for management. The fundamental premise that rangelands can exhibit multiple states is now widely accepted. The current application of STMs for managem...

  10. The transition of mouse pluripotent stem cells from the naïve to the primed state requires Fas signaling through 3-O sulfated heparan sulfate structures recognized by the HS4C3 antibody

    Energy Technology Data Exchange (ETDEWEB)

    Hirano, Kazumi [Laboratory of Cell Biology, Department of Bioinformatics, Faculty of Engineering, Soka University, 1-236 Tangi-cho, Hachioji, Tokyo 192-8577 (Japan); Van Kuppevelt, Toin H. [Department of Biochemistry, Nijmegen Center for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, 280 P.O. Box 9101, 6500 HB Nijmegen (Netherlands); Nishihara, Shoko, E-mail: shoko@soka.ac.jp [Laboratory of Cell Biology, Department of Bioinformatics, Faculty of Engineering, Soka University, 1-236 Tangi-cho, Hachioji, Tokyo 192-8577 (Japan)

    2013-01-18

    Highlights: ► Fas transcript increases during the transition from the naïve to the primed state. ► 3OST-5 transcript, the HS4C3 epitope synthesis gene, increases during the transition. ► Fas signaling regulates the transition from the naïve to the primed state. ► HS4C3-binding epitope regulates the transition from the naïve to the primed state. ► Fas signaling is regulated by the HS4C3 epitope during the transition. -- Abstract: The characteristics of pluripotent embryonic stem cells of human and mouse are different. The properties of human embryonic stem cells (hESCs) are similar to those of mouse epiblast stem cells (mEpiSCs), which are in a later developmental pluripotency state, the so-called “primed state” compared to mouse embryonic stem cells (mESCs) which are in a naïve state. As a result of the properties of the primed state, hESCs proliferate slowly, cannot survive as single cells, and can only be transfected with genes at low efficiency. Generating hESCs in the naïve state is necessary to overcome these problems and allow their application in regenerative medicine. Therefore, clarifying the mechanism of the transition between the naïve and primed states in pluripotent stem cells is important for the establishment of stable methods of generating naïve state hESCs. However, the signaling pathways which contribute to the transition between the naïve and primed states are still unclear. In this study, we carried out induction from mESCs to mEpiSC-like cells (mEpiSCLCs), and observed an increase in the activation of Fas signaling during the induction. The expression of Fgf5, an epiblast marker, was diminished by inhibition of Fas signaling using the caspase-8 and -3 blocking peptides, IETD and DEVD, respectively. Furthermore, during the induction, we observed increased expression of 3-O sulfated heparan sulfate (HS) structures synthesized by HS 3-O-sulfotransferase (3OST), which are recognized by the HS4C3 antibody (HS4C3-binding epitope

  11. The transition of mouse pluripotent stem cells from the naïve to the primed state requires Fas signaling through 3-O sulfated heparan sulfate structures recognized by the HS4C3 antibody

    International Nuclear Information System (INIS)

    Hirano, Kazumi; Van Kuppevelt, Toin H.; Nishihara, Shoko

    2013-01-01

    Highlights: ► Fas transcript increases during the transition from the naïve to the primed state. ► 3OST-5 transcript, the HS4C3 epitope synthesis gene, increases during the transition. ► Fas signaling regulates the transition from the naïve to the primed state. ► HS4C3-binding epitope regulates the transition from the naïve to the primed state. ► Fas signaling is regulated by the HS4C3 epitope during the transition. -- Abstract: The characteristics of pluripotent embryonic stem cells of human and mouse are different. The properties of human embryonic stem cells (hESCs) are similar to those of mouse epiblast stem cells (mEpiSCs), which are in a later developmental pluripotency state, the so-called “primed state” compared to mouse embryonic stem cells (mESCs) which are in a naïve state. As a result of the properties of the primed state, hESCs proliferate slowly, cannot survive as single cells, and can only be transfected with genes at low efficiency. Generating hESCs in the naïve state is necessary to overcome these problems and allow their application in regenerative medicine. Therefore, clarifying the mechanism of the transition between the naïve and primed states in pluripotent stem cells is important for the establishment of stable methods of generating naïve state hESCs. However, the signaling pathways which contribute to the transition between the naïve and primed states are still unclear. In this study, we carried out induction from mESCs to mEpiSC-like cells (mEpiSCLCs), and observed an increase in the activation of Fas signaling during the induction. The expression of Fgf5, an epiblast marker, was diminished by inhibition of Fas signaling using the caspase-8 and -3 blocking peptides, IETD and DEVD, respectively. Furthermore, during the induction, we observed increased expression of 3-O sulfated heparan sulfate (HS) structures synthesized by HS 3-O-sulfotransferase (3OST), which are recognized by the HS4C3 antibody (HS4C3-binding epitope

  12. Molecular water oxidation mechanisms followed by transition metals: state of the art.

    Science.gov (United States)

    Sala, Xavier; Maji, Somnath; Bofill, Roger; García-Antón, Jordi; Escriche, Lluís; Llobet, Antoni

    2014-02-18

    One clean alternative to fossil fuels would be to split water using sunlight. However, to achieve this goal, researchers still need to fully understand and control several key chemical reactions. One of them is the catalytic oxidation of water to molecular oxygen, which also occurs at the oxygen evolving center of photosystem II in green plants and algae. Despite its importance for biology and renewable energy, the mechanism of this reaction is not fully understood. Transition metal water oxidation catalysts in homogeneous media offer a superb platform for researchers to investigate and extract the crucial information to describe the different steps involved in this complex reaction accurately. The mechanistic information extracted at a molecular level allows researchers to understand both the factors that govern this reaction and the ones that derail the system to cause decomposition. As a result, rugged and efficient water oxidation catalysts with potential technological applications can be developed. In this Account, we discuss the current mechanistic understanding of the water oxidation reaction catalyzed by transition metals in the homogeneous phase, based on work developed in our laboratories and complemented by research from other groups. Rather than reviewing all of the catalysts described to date, we focus systematically on the several key elements and their rationale from molecules studied in homogeneous media. We organize these catalysts based on how the crucial oxygen-oxygen bond step takes place, whether via a water nucleophilic attack or via the interaction of two M-O units, rather than based on the nuclearity of the water oxidation catalysts. Furthermore we have used DFT methodology to characterize key intermediates and transition states. The combination of both theory and experiments has allowed us to get a complete view of the water oxidation cycle for the different catalysts studied. Finally, we also describe the various deactivation pathways for

  13. Growth of single crystals of BaFe12O19 by solid state crystal growth

    Science.gov (United States)

    Fisher, John G.; Sun, Hengyang; Kook, Young-Geun; Kim, Joon-Seong; Le, Phan Gia

    2016-10-01

    Single crystals of BaFe12O19 are grown for the first time by solid state crystal growth. Seed crystals of BaFe12O19 are buried in BaFe12O19+1 wt% BaCO3 powder, which are then pressed into pellets containing the seed crystals. During sintering, single crystals of BaFe12O19 up to ∼130 μm thick in the c-axis direction grow on the seed crystals by consuming grains from the surrounding polycrystalline matrix. Scanning electron microscopy-energy dispersive spectroscopy analysis shows that the single crystal and the surrounding polycrystalline matrix have the same chemical composition. Micro-Raman scattering shows the single crystal to have the BaFe12O19 structure. The optimum growth temperature is found to be 1200 °C. The single crystal growth behavior is explained using the mixed control theory of grain growth.

  14. Surface-Induced Frustration in Solid State Polymorphic Transition of Native Cellulose Nanocrystals.

    Science.gov (United States)

    Salminen, Reeta; Baccile, Niki; Reza, Mehedi; Kontturi, Eero

    2017-06-12

    The presence of an interface generally influences crystallization of polymers from melt or from solution. Here, by contrast, we explore the effect of surface immobilization in a direct solid state polymorphic transition on individual cellulose nanocrystals (CNCs), extracted from a plant-based origin. The conversion from native cellulose I to cellulose III crystal occurred via a host-guest inclusion of ethylene diamine inside the crystal. A 60% reduction in CNC width (height) in atomic force microscopy images suggested that when immobilized on a flat modified silica surface, the stresses caused by the inclusion or the subsequent regeneration resulted in exfoliation, hypothetically, between the van der Waals bonded sheets within the crystal. Virtually no changes in dimensions were visible when the polymorphic transition was performed to nonimmobilized CNCs in bulk dispersion. With reservations and by acknowledging the obvious dissimilarities, the exfoliation of cellulose crystal sheets can be viewed as analogous to exfoliation of 2D structures like graphene from a van der Waals stacked solid. Here, the detachment is triggered by an inclusion of a guest molecule inside a host cellulose crystal and the stresses caused by the firm attachment of the CNC on a solid substrate, leading to detachment of molecular sheets or stacks of sheets.

  15. Many-particle nucleon-nucleon forces from nuclear single-particle states

    OpenAIRE

    Birbrair, B. L.; Ryazanov, V. I.

    1999-01-01

    As follows from the energies of single-particle states in ^{40}Ca, ^{90}Zr and ^{208}Pb nuclei the contribution of many-particle NN forces to the nuclear single-particle potential is at least the sum of repulsive and attractive parts resulting from three-particle and four-particle forces respectively. In addition the specified nucleon density distributions in the above nuclei are determined from both the 1 GeV proton-nucleus elastic scattering and the single-particle energies.

  16. Pressure-induced phase transitions in organic molecular crystals: a combination of x-ray single-crystal and powder diffraction, raman and IR-spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Boldyreva, E V; Goryainov, S V; Seryotkin, Y V; Kolesnik, E N; Shakhtshneider, T P; Ivashevskaya, S N; Drebushchak, T N [Research and Education Center ' Molecular Design and Ecologically Safe Technologies' , REC-008, Novosibirsk State University (Russian Federation); Sowa, H [Goettingen University (Germany); Ahsbahs, H; Chernyshev, V V [Marburg University (Germany); Dmitriev, V P [Swiss-Norwegian Beamline ESRF, Grenoble (France)], E-mail: boldyrev@nsu.ru

    2008-07-15

    The contribution summarizes the results of recent studies of phase transitions induced by high pressure in a number of molecular organic crystals, such as polymorphs of paracetamol, chlorpropamide, polymorphs of glycine, L- and DL-serine, {beta}-alanine. The main attention is paid to the following topics: (1) Reversible / irreversible transformations; (2) Different behavior of single crystals / powders; (3) The role of pressure-transmitting liquid; (4) The role of the kinetic factors: phase transitions on decompression, or after a long storage at a selected pressure; (5) Isosymmetric phase transitions; (6) The role of the changes in the hydrogen bond networks / intramolecular conformational changes in the phase transitions; (7) Superstructures / nanostructures formed as a result of pressure-induced phase transitions.

  17. Transition by breaking of analyticity in the ground state of Josephson junction arrays as a static signature of the vortex jamming transition

    KAUST Repository

    Nogawa, Tomoaki

    2012-05-22

    We investigate the ground state of the irrationally frustrated Josephson junction array with a controlling anisotropy parameter λ that is the ratio of the longitudinal Josephson coupling to the transverse one. We find that the ground state has one-dimensional periodicity whose reciprocal lattice vector depends on λ and is incommensurate with the substrate lattice. Approaching the isotropic point λ=1, the so-called hull function of the ground state exhibits analyticity breaking similar to the Aubry transition in the Frenkel-Kontorova model. We find a scaling law for the harmonic spectrum of the hull functions, which suggests the existence of a characteristic length scale diverging at the isotropic point. This critical behavior is directly connected to the jamming transition previously observed in the current-voltage characteristics by a numerical simulation. On top of the ground state there is a gapless continuous band of metastable states, which exhibit the same critical behavior as the ground state. © 2012 American Physical Society.

  18. Post-transition state dynamics and product energy partitioning following thermal excitation of the F∙∙∙HCH2 CN transition state: Disagreement with experiment

    Energy Technology Data Exchange (ETDEWEB)

    Pratihar, Subha [Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409-1061, USA; Ma, Xinyou [Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409-1061, USA; Xie, Jing [Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, USA; Scott, Rebecca [Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409-1061, USA; Gao, Eric [Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409-1061, USA; Ruscic, Branko [Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, USA and Computation Institute, University of Chicago, Chicago, Illinois 60637, USA; Aquino, Adelia J. A. [Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409-1061, USA; School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, People’s Republic of China; Institute for Soil Research University of Natural Resources and Life Sciences Vienna, Peter-Jordan-Strasse 82, A-1190 Vienna, Austria; Setser, Donald W. [Institute for Soil Research University of Natural Resources and Life Sciences Vienna, Peter-Jordan-Strasse 82, A-1190 Vienna, Austria; Hase, William L. [Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409-1061, USA

    2017-10-14

    Born-Oppenheimer direct dynamics simulations were performed to study atomistic details of the F + CH3CN → HF + CH2CN H-atom abstraction reaction. The simulation trajectories were calculated with a combined M06-2X/MP2 algorithm utilizing the 6-311++G** basis set. In accord with experiment and assuming the accuracy of transition state theory (TST), the trajectories were initiated at the F-HCH2CN abstraction TS with a 300 K Boltzmann distribution of energy and directed towards products. Recrossing of the TS was negligible, confirming the accuracy of TST for the simulation. HF formation was rapid, occurring within 0.014 ps of the trajectory initiation. The intrinsic reaction coordinate (IRC) for reaction involves rotation of HF about CH2CN and then trapping in the CH2CN-HF post-reaction potential energy well of ~10 kcal/mol with respect to the HF + CH2CN products. In contrast to this IRC, five different trajectory types were observed, with the majority involving direct dissociation and only 11% approximately following the IRC. The HF vibrational and rotational quantum numbers, n and J, were calculated when HF was initially formed and they increase as potential energy is released in forming the HF + CH2CN products. The population of the HF product vibrational states is only in qualitative agreement with experiment, with the simulations showing depressed and enhanced populations of the n = 1 and 2 states as compared to experiment. From the simulations and with an anharmonic zero-point energy constraint, the percentage partitioning of the product energy to relative translation, HF rotation, HF vibration, CH2CN rotation and CH2CN vibration is 5, 11, 60, 7, and 16%, respectively. In contrast the experimental energy partitioning percentages to HF rotation and vibration are 6 and 41%. Comparisons are made between the current simulation and those for other F + H

  19. Isotope Substitution of Promiscuous Alcohol Dehydrogenase Reveals the Origin of Substrate Preference in the Transition State.

    Science.gov (United States)

    Behiry, Enas M; Ruiz-Pernia, J Javier; Luk, Louis; Tuñón, Iñaki; Moliner, Vicent; Allemann, Rudolf K

    2018-03-12

    The origin of substrate preference in promiscuous enzymes was investigated by enzyme isotope labelling of the alcohol dehydrogenase from Geobacillus stearothermophilus (BsADH). At physiological temperature, protein dynamic coupling to the reaction coordinate was insignificant. However, the extent of dynamic coupling was highly substrate-dependent at lower temperatures. For benzyl alcohol, an enzyme isotope effect larger than unity was observed, whereas the enzyme isotope effect was close to unity for isopropanol. Frequency motion analysis on the transition states revealed that residues surrounding the active site undergo substantial displacement during catalysis for sterically bulky alcohols. BsADH prefers smaller substrates, which cause less protein friction along the reaction coordinate and reduced frequencies of dynamic recrossing. This hypothesis allows a prediction of the trend of enzyme isotope effects for a wide variety of substrates. © 2018 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  20. Quantum variational transition state theory for hydrogen tunneling in enzyme catalysis.

    Science.gov (United States)

    Pollak, Eli

    2012-11-01

    Experiments in recent years have shown that there is a large kinetic isotope effect in the rate of transfer of hydrogen or deuterium in enzymatic reactions of soybean lipoxygenase-1. The kinetic isotope effect (KIE) is only weakly temperature dependent but varies significantly in the presence of mutants whose functional groups are located rather far from the reaction center. In this paper we suggest that variational transition state theory as applied to dissipative systems, above the crossover temperature between deep tunneling and thermal activation, may be used as a paradigm for understanding the dynamics of these reactions. We find that the theory fits the experimental data rather well. The effects of different mutants are readily interpreted in terms of the friction they exert on the reaction center. Increasing the distal functional group increases the friction and thus lowers the kinetic isotope effect.

  1. S-matrix decomposition, natural reaction channels, and the quantum transition state approach to reactive scattering.

    Science.gov (United States)

    Manthe, Uwe; Ellerbrock, Roman

    2016-05-28

    A new approach for the quantum-state resolved analysis of polyatomic reactions is introduced. Based on the singular value decomposition of the S-matrix, energy-dependent natural reaction channels and natural reaction probabilities are defined. It is shown that the natural reaction probabilities are equal to the eigenvalues of the reaction probability operator [U. Manthe and W. H. Miller, J. Chem. Phys. 99, 3411 (1993)]. Consequently, the natural reaction channels can be interpreted as uniquely defined pathways through the transition state of the reaction. The analysis can efficiently be combined with reactive scattering calculations based on the propagation of thermal flux eigenstates. In contrast to a decomposition based straightforwardly on thermal flux eigenstates, it does not depend on the choice of the dividing surface separating reactants from products. The new approach is illustrated studying a prototypical example, the H + CH4 → H2 + CH3 reaction. The natural reaction probabilities and the contributions of the different vibrational states of the methyl product to the natural reaction channels are calculated and discussed. The relation between the thermal flux eigenstates and the natural reaction channels is studied in detail.

  2. Optimal precursors triggering the Kuroshio Extension state transition obtained by the Conditional Nonlinear Optimal Perturbation approach

    Science.gov (United States)

    Zhang, Xing; Mu, Mu; Wang, Qiang; Pierini, Stefano

    2017-06-01

    In this study, the initial perturbations that are the easiest to trigger the Kuroshio Extension (KE) transition connecting a basic weak jet state and a strong, fairly stable meandering state, are investigated using a reduced-gravity shallow water ocean model and the CNOP (Conditional Nonlinear Optimal Perturbation) approach. This kind of initial perturbation is called an optimal precursor (OPR). The spatial structures and evolutionary processes of the OPRs are analyzed in detail. The results show that most of the OPRs are in the form of negative sea surface height (SSH) anomalies mainly located in a narrow band region south of the KE jet, in basic agreement with altimetric observations. These negative SSH anomalies reduce the meridional SSH gradient within the KE, thus weakening the strength of the jet. The KE jet then becomes more convoluted, with a high-frequency and large-amplitude variability corresponding to a high eddy kinetic energy level; this gradually strengthens the KE jet through an inverse energy cascade. Eventually, the KE reaches a high-energy state characterized by two well defined and fairly stable anticyclonic meanders. Moreover, sensitivity experiments indicate that the spatial structures of the OPRs are not sensitive to the model parameters and to the optimization times used in the analysis.

  3. Effect of the compressive stress on both polarization rotation and phase transitions in PMN-30%PT single crystal

    Directory of Open Access Journals (Sweden)

    Hui Zhang

    2014-05-01

    Full Text Available In this paper, we have investigated the dependence of both the electromechanical effect and the electrostriction on the compressive stress in PMN-30%PT single crystal on the basis of single domain polarization rotation model. In the model, the electroelastic energy induced by the compressive stress is taken into account. The results have demonstrated that the compressive stress can lead to a significant change in the initial polarization state in the crystal. The reason lies in the stress induced anisotropy which is the coupling between the compressive stress and the electrostrictive coefficients. Thus, the initial polarization state in single crystal is determined by the combination of both electrocrystalline anisotropy and the stress induced anisotropy. The compressive stress along the [100] axis can make the polarization in the crystal be perpendicular to the stress direction, and make it difficult to be polarized to the saturation. This model is useful for better understanding both the polarization rotation and electromechanical effect in ferroelectric crystals with the compressive stress present.

  4. First detection of the ground state JK = 1 sub 0 going to 0 sub 0 submillimeter transition of interstellar ammonia

    Science.gov (United States)

    Keene, J.; Blake, G. A.; Phillips, T. G.

    1983-01-01

    The JK = 1 sub 0 approaching O sub 0 transition of ammonia at 572.5 GHz was detected in OMC-1 from NASA's Kuiper Airborne Observatory. The central velocity of the line (VLSR approximately = 9 km/s) indicates that it originates in the molecular cloud material, not the hot core. The derived filling factor of approximately 0.09 in a 2' beam implies a source diameter of approximately 35" if it is a single clump. This clump area is much larger than that derived from observations of the sub 1 inversion transition. The larger optical depth in the 1 sub 0 approaching 0 sub 0 transition (75-350) can account for the increased source area and linewidth as compared with those seen in the 1 sub 0 inversion transition.

  5. Silicon-Vacancy Spin Qubit in Diamond: A Quantum Memory Exceeding 10 ms with Single-Shot State Readout

    Science.gov (United States)

    Sukachev, D. D.; Sipahigil, A.; Nguyen, C. T.; Bhaskar, M. K.; Evans, R. E.; Jelezko, F.; Lukin, M. D.

    2017-12-01

    The negatively charged silicon-vacancy (SiV- ) color center in diamond has recently emerged as a promising system for quantum photonics. Its symmetry-protected optical transitions enable the creation of indistinguishable emitter arrays and deterministic coupling to nanophotonic devices. Despite this, the longest coherence time associated with its electronic spin achieved to date (˜250 ns ) has been limited by coupling to acoustic phonons. We demonstrate coherent control and suppression of phonon-induced dephasing of the SiV- electronic spin coherence by 5 orders of magnitude by operating at temperatures below 500 mK. By aligning the magnetic field along the SiV- symmetry axis, we demonstrate spin-conserving optical transitions and single-shot readout of the SiV- spin with 89% fidelity. Coherent control of the SiV- spin with microwave fields is used to demonstrate a spin coherence time T2 of 13 ms and a spin relaxation time T1 exceeding 1 s at 100 mK. These results establish the SiV- as a promising solid-state candidate for the realization of quantum networks.

  6. Electronic states and optical properties of single donor in GaN conical quantum dot with spherical edge

    Science.gov (United States)

    El Aouami, A.; Feddi, E.; El-Yadri, M.; Aghoutane, N.; Dujardin, F.; Duque, C. A.; Phuc, Huynh Vinh

    2018-02-01

    In this paper we present a theoretical investigation of quantum confinement effects on the electron and single donor states in GaN conical quantum dot with spherical edge. In the framework of the effective mass approximation, the Schrödinger equations of electron and donor have been solved analytically in an infinite potential barrier model. Our calculations show that the energies of electron and donor impurity are affected by the two characteristic parameters of the structure which are the angle Ω and the radial dimension R. We show that, despite the fact that the reduction of the two parameters Ω and R leads to the same confinement effects, the energy remains very sensitive to the variation of the radial part than the variation of the angular part. The analysis of the photoionization cross-section corresponding to optical transitions between the conduction band and the first donor energy level shows clearly that the reduction of the radius R causes a shift in resonance peaks towards the high energies. On the other hand, the optical transitions between 1 s - 1 p , 1 p - 1 d and 1 p - 2 s show that the increment of the conical aperture Ω (or reduction of R) implies a displacement of the excitation energy to higher energies.

  7. Using state-and-transition modeling to account for imperfect detection in invasive species management

    Science.gov (United States)

    Frid, Leonardo; Holcombe, Tracy; Morisette, Jeffrey T.; Olsson, Aaryn D.; Brigham, Lindy; Bean, Travis M.; Betancourt, Julio L.; Bryan, Katherine

    2013-01-01

    Buffelgrass, a highly competitive and flammable African bunchgrass, is spreading rapidly across both urban and natural areas in the Sonoran Desert of southern and central Arizona. Damages include increased fire risk, losses in biodiversity, and diminished revenues and quality of life. Feasibility of sustained and successful mitigation will depend heavily on rates of spread, treatment capacity, and cost–benefit analysis. We created a decision support model for the wildland–urban interface north of Tucson, AZ, using a spatial state-and-transition simulation modeling framework, the Tool for Exploratory Landscape Scenario Analyses. We addressed the issues of undetected invasions, identifying potentially suitable habitat and calibrating spread rates, while answering questions about how to allocate resources among inventory, treatment, and maintenance. Inputs to the model include a state-and-transition simulation model to describe the succession and control of buffelgrass, a habitat suitability model, management planning zones, spread vectors, estimated dispersal kernels for buffelgrass, and maps of current distribution. Our spatial simulations showed that without treatment, buffelgrass infestations that started with as little as 80 ha (198 ac) could grow to more than 6,000 ha by the year 2060. In contrast, applying unlimited management resources could limit 2060 infestation levels to approximately 50 ha. The application of sufficient resources toward inventory is important because undetected patches of buffelgrass will tend to grow exponentially. In our simulations, areas affected by buffelgrass may increase substantially over the next 50 yr, but a large, upfront investment in buffelgrass control could reduce the infested area and overall management costs.

  8. Prediction of monomer reactivity in radical copolymerizations from transition state quantum chemical descriptors

    Directory of Open Access Journals (Sweden)

    Zhengde Tan

    2013-01-01

    Full Text Available In comparison with the Q-e scheme, the Revised Patterns Scheme: the U, V Version (the U-V scheme has greatly improved both its accessibility and its accuracy in interpreting and predicting the reactivity of a monomer in free-radical copolymerizations. Quantitative structure-activity relationship (QSAR models were developed to predict the reactivity parameters u and v of the U-V scheme, by applying genetic algorithm (GA and support vector machine (SVM techniques. Quantum chemical descriptors used for QSAR models were calculated from transition state species with structures C¹H3 - C²HR³• or •C¹H2 - C²H2R³ (formed from vinyl monomers C¹H²=C²HR³ + H•, using density functional theory (DFT, at the UB3LYP level of theory with 6-31G(d basis set. The optimum support vector regression (SVR model of the reactivity parameter u based on Gaussian radial basis function (RBF kernel (C = 10, ε = 10- 5 and γ = 1.0 produced root-mean-square (rms errors for the training, validation and prediction sets being 0.220, 0.326 and 0.345, respectively. The optimal SVR model for v with the RBF kernel (C = 20, ε = 10- 4 and γ = 1.2 produced rms errors for the training set of 0.123, the validation set of 0.206 and the prediction set of 0.238. The feasibility of applying the transition state quantum chemical descriptors to develop SVM models for reactivity parameters u and v in the U-V scheme has been demonstrated.

  9. Linking state-and-transition simulation and timber supply models for forest biomass production scenarios

    Science.gov (United States)

    Costanza, Jennifer; Abt, Robert C.; McKerrow, Alexa; Collazo, Jaime

    2015-01-01

    We linked state-and-transition simulation models (STSMs) with an economics-based timber supply model to examine landscape dynamics in North Carolina through 2050 for three scenarios of forest biomass production. Forest biomass could be an important source of renewable energy in the future, but there is currently much uncertainty about how biomass production would impact landscapes. In the southeastern US, if forests become important sources of biomass for bioenergy, we expect increased land-use change and forest management. STSMs are ideal for simulating these landscape changes, but the amounts of change will depend on drivers such as timber prices and demand for forest land, which are best captured with forest economic models. We first developed state-and-transition model pathways in the ST-Sim software platform for 49 vegetation and land-use types that incorporated each expected type of landscape change. Next, for the three biomass production scenarios, the SubRegional Timber Supply Model (SRTS) was used to determine the annual areas of thinning and harvest in five broad forest types, as well as annual areas converted among those forest types, agricultural, and urban lands. The SRTS output was used to define area targets for STSMs in ST-Sim under two scenarios of biomass production and one baseline, business-as-usual scenario. We show that ST-Sim output matched SRTS targets in most cases. Landscape dynamics results indicate that, compared with the baseline scenario, forest biomass production leads to more forest and, specifically, more intensively managed forest on the landscape by 2050. Thus, the STSMs, informed by forest economics models, provide important information about potential landscape effects of bioenergy production.

  10. Single-molecule junction of an overcrowded ethylene with binary conductance states

    Science.gov (United States)

    Koike, Masato; Fujii, Shintaro; Cho, Haruna; Shoji, Yoshiaki; Nishino, Tomoaki; Fukushima, Takanori; Kiguchi, Manabu

    2018-03-01

    Overcrowded ethylene 1 shows mechanochromic behavior with contrasting color change between yellow and violet arising from its conformational isomerization, which should also be accompanied by the change in the electronic structure. Here, we report a single-molecule electronic study of 1 using scanning tunneling microcopy (STM) and STM-based break junction techniques. The single-molecule junction of 1 sandwiched by Au electrodes showed two distinct high- and low-conductance states with the conductance values of 0.003 and 0.0002 G 0. The high-conductance state is one order of magnitude more conductive than the low-conductance state. The two states can be ascribed to two conformational isomers of 1 in the junction.

  11. Observation of quantum state collapse and revival due to the single-photon Kerr effect.

    Science.gov (United States)

    Kirchmair, Gerhard; Vlastakis, Brian; Leghtas, Zaki; Nigg, Simon E; Paik, Hanhee; Ginossar, Eran; Mirrahimi, Mazyar; Frunzio, Luigi; Girvin, S M; Schoelkopf, R J

    2013-03-14

    To create and manipulate non-classical states of light for quantum information protocols, a strong, nonlinear interaction at the single-photon level is required. One approach to the generation of suitable interactions is to couple photons to atoms, as in the strong coupling regime of cavity quantum electrodynamic systems. In these systems, however, the quantum state of the light is only indirectly controlled by manipulating the atoms. A direct photon-photon interaction occurs in so-called Kerr media, which typically induce only weak nonlinearity at the cost of significant loss. So far, it has not been possible to reach the single-photon Kerr regime, in which the interaction strength between individual photons exceeds the loss rate. Here, using a three-dimensional circuit quantum electrodynamic architecture, we engineer an artificial Kerr medium that enters this regime and allows the observation of new quantum effects. We realize a gedanken experiment in which the collapse and revival of a coherent state can be observed. This time evolution is a consequence of the quantization of the light field in the cavity and the nonlinear interaction between individual photons. During the evolution, non-classical superpositions of coherent states (that is, multi-component 'Schrödinger cat' states) are formed. We visualize this evolution by measuring the Husimi Q function and confirm the non-classical properties of these transient states by cavity state tomography. The ability to create and manipulate superpositions of coherent states in such a high-quality-factor photon mode opens perspectives for combining the physics of continuous variables with superconducting circuits. The single-photon Kerr effect could be used in quantum non-demolition measurement of photons, single-photon generation, autonomous quantum feedback schemes and quantum logic operations.

  12. Complete transfer of populations from a single state to a preselected superposition of states using piecewise adiabatic passage: Experiment

    International Nuclear Information System (INIS)

    Zhdanovich, S.; Shapiro, E. A.; Hepburn, J. W.; Shapiro, M.; Milner, V.

    2009-01-01

    We demonstrate a method of adiabatic population transfer from a single quantum state into a coherent superposition of states. The transfer is executed with femtosecond pulses, spectrally shaped in a simple and intuitive manner, which does not require iterative feedback-controlled loops. In contrast to nonadiabatic methods of excitation, our approach is not sensitive to the exact value of laser intensity. We show that the population transfer is complete, and analyze the possibility of controlling the relative phases and amplitudes of the excited eigenstates. We discuss the limitations of the proposed control methods due to the dynamic level shifts and suggest ways of reducing their influence.

  13. Method for preparation and readout of polyatomic molecules in single quantum states

    Science.gov (United States)

    Patterson, David

    2018-03-01

    Polyatomic molecular ions contain many desirable attributes of a useful quantum system, including rich internal degrees of freedom and highly controllable coupling to the environment. To date, the vast majority of state-specific experimental work on molecular ions has concentrated on diatomic species. The ability to prepare and read out polyatomic molecules in single quantum states would enable diverse experimental avenues not available with diatomics, including new applications in precision measurement, sensitive chemical and chiral analysis at the single-molecule level, and precise studies of Hz-level molecular tunneling dynamics. While cooling the motional state of a polyatomic ion via sympathetic cooling with a laser-cooled atomic ion is straightforward, coupling this motional state to the internal state of the molecule has proven challenging. Here we propose a method for readout and projective measurement of the internal state of a trapped polyatomic ion. The method exploits the rich manifold of technically accessible rotational states in the molecule to realize robust state preparation and readout with far less stringent engineering than quantum logic methods recently demonstrated on diatomic molecules. The method can be applied to any reasonably small (≲10 atoms) polyatomic ion with an anisotropic polarizability.

  14. Nonlinear magnetoelectric effect in paraelectric state of Co4Nb2O9 single crystal

    Czech Academy of Sciences Publication Activity Database

    Cao, Ym.; Deng, Gc.; Beran, Přemysl; Feng, Zj.; Kang, Bj.; Zhang, Jc.; Guiblin, N.; Dkhil, B.; Ren, W.; Cao, Sx.

    2017-01-01

    Roč. 7, č. 10 (2017), č. článku 14079. ISSN 2045-2322 Institutional support: RVO:61389005 Keywords : magnetoelectric * single crystal * neutron diffraction Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 4.259, year: 2016

  15. Transit Marketing : Review of the State-of-the-Art and a Handbook of Current Practice

    Science.gov (United States)

    1985-04-01

    Over the past decade, marketing has been given increased emphasis as a way to improve both transit rideship and productivity. While there is near universal agreement among transit managers that some level of marketing is necessary, there is far from ...

  16. Multi-state discrimination below the quantum noise limit at the single-photon level

    Science.gov (United States)

    Ferdinand, A. R.; DiMario, M. T.; Becerra, F. E.

    2017-10-01

    Measurements approaching the ultimate quantum limits of sensitivity are central in quantum information processing, quantum metrology, and communication. Quantum measurements to discriminate multiple states at the single-photon level are essential for optimizing information transfer in low-power optical communications and quantum communications, and can enhance the capabilities of many quantum information protocols. Here, we theoretically investigate and experimentally demonstrate the discrimination of multiple coherent states of light with sensitivities surpassing the quantum noise limit (QNL) at the single-photon level under realistic conditions of loss and noise based on strategies implementing globally-optimized adaptive measurements with single photon counting and displacement operations. These discrimination strategies can provide realistic advantages to enhance information transfer at low powers, and are compatible with photon number resolving detection, which provides robustness at high powers, thus allowing for surpassing the QNL at arbitrary input power levels under realistic conditions.

  17. DeepCpG: accurate prediction of single-cell DNA methylation states using deep learning.

    Science.gov (United States)

    Angermueller, Christof; Lee, Heather J; Reik, Wolf; Stegle, Oliver

    2017-04-11

    Recent technological advances have enabled DNA methylation to be assayed at single-cell resolution. However, current protocols are limited by incomplete CpG coverage and hence methods to predict missing methylation states are critical to enable genome-wide analyses. We report DeepCpG, a computational approach based on deep neural networks to predict methylation states in single cells. We evaluate DeepCpG on single-cell methylation data from five cell types generated using alternative sequencing protocols. DeepCpG yields substantially more accurate predictions than previous methods. Additionally, we show that the model parameters can be interpreted, thereby providing insights into how sequence composition affects methylation variability.

  18. Temperature-dependent Hammond behavior in a protein-folding reaction: analysis of transition-state movement and ground-state effects.

    Science.gov (United States)

    Taskent, Humeyra; Cho, Jae-Hyun; Raleigh, Daniel P

    2008-05-02

    Characterization of the transition-state ensemble and the nature of the free-energy barrier for protein folding are areas of intense activity and some controversy. A key issue that has emerged in recent years is the width of the free-energy barrier and the susceptibility of the transition state to movement. Here we report denaturant-induced and temperature-dependent folding studies of a small mixed alpha-beta protein, the N-terminal domain of L9 (NTL9). The folding of NTL9 was determined using fluorescence-detected stopped-flow fluorescence measurements conducted at seven different temperatures between 11 and 40 degrees C. Plots of the log of the observed first-order rate constant versus denaturant concentration, "chevron plots," displayed the characteristic V shape expected for two-state folding. There was no hint of deviation from linearity even at the lowest denaturant concentrations. The relative position of the transition state, as judged by the Tanford beta parameter, beta(T), shifts towards the native state as the temperature is increased. Analysis of the temperature dependence of the kinetic and equilibrium m values indicates that the effect is due to significant movement of the transition state and also includes a contribution from temperature-dependent ground-state effects. Analysis of the Leffler plots, plots of Delta G versus Delta G degrees, and their cross-interaction parameters confirms the transition-state movement. Since the protein is destabilized at high temperature, the shift represents a temperature-dependent Hammond effect. This provides independent confirmation of a recent theoretical prediction. The magnitude of the temperature-denaturant cross-interaction parameter is larger for NTL9 than has been reported for the few other cases studied. The implications for temperature-dependent studies of protein folding are discussed.

  19. Do spatially homogenising and heterogenising processes affect transitions between alternative stable states?

    NARCIS (Netherlands)

    Groen, Thomas A.; Vijver, Van de Claudius A.D.M.; Langevelde, Van Frank

    2017-01-01

    Large-scale sudden transitions in ecosystems are expected as result of changing global climate or land use. Current theory predicts such sudden transitions especially to occur in spatially homogeneous ecosystems, whereas transitions in spatially heterogeneous systems will be more gradual. The

  20. Displacement-enhanced entanglement distillation of single-mode-squeezed entangled states

    DEFF Research Database (Denmark)

    Tipsmark, Anders; Neergaard-Nielsen, Jonas Schou; Andersen, Ulrik Lund

    2013-01-01

    It has been shown that entanglement distillation of Gaussian entangled states by means of local photon subtraction can be improved by local Gaussian transformations. Here we show that a similar effect can be expected for the distillation of an asymmetric Gaussian entangled state that is produced...... by a single squeezed beam. We show that for low initial entanglement, our largely simplified protocol generates more entanglement than previous proposed protocols. Furthermore, we show that the distillation scheme also works efficiently on decohered entangled states as well as with a practical photon...

  1. Hydrostatic pressure effects on the state density and optical transitions in quantum dots

    International Nuclear Information System (INIS)

    Galindez-Ramirez, G; Perez-Merchancano, S T; Paredes Gutierrez, H; Gonzalez, J D

    2010-01-01

    Using the effective mass approximation and variational method we have computed the effects of hydrostatic pressure on the absorption and photoluminescence spectra in spherical quantum dot GaAs-(Ga, Al) As, considering a finite confinement potential of this particular work we show the optical transitions in quantum of various sizes in the presence of hydrogenic impurities and hydrostatic pressure effects. Our first result describes the spectrum of optical absorption of 500 A QD for different values of hydrostatic pressure P = 0, 20 and 40 Kbar. The absorption peaks are sensitive to the displacement of the impurity center to the edge of the quantum dot and even more when the hydrostatic pressure changes in both cases showing that to the extent that these two effects are stronger quantum dots respond more efficiently. Also this result can be seen in the study of the photoluminescence spectrum as in the case of acceptor impurities consider them more efficiently capture carriers or electrons that pass from the conduction band to the valence band. Density states with randomly distributed impurity show that the additional peaks in the curves of the density of impurity states appear due to the presence of the additional hydrostatic pressure effects.

  2. Potassium availability triggers Mycobacterium tuberculosis transition to, and resuscitation from, non-culturable (dormant) states.

    Science.gov (United States)

    Salina, Elena G; Waddell, Simon J; Hoffmann, Nadine; Rosenkrands, Ida; Butcher, Philip D; Kaprelyants, Arseny S

    2014-10-01

    Dormancy in non-sporulating bacteria is an interesting and underexplored phenomenon with significant medical implications. In particular, latent tuberculosis may result from the maintenance of Mycobacterium tuberculosis bacilli in non-replicating states in infected individuals. Uniquely, growth of M. tuberculosis in aerobic conditions in potassium-deficient media resulted in the generation of bacilli that were non-culturable (NC) on solid media but detectable in liquid media. These bacilli were morphologically distinct and tolerant to cell-wall-targeting antimicrobials. Bacterial counts on solid media quickly recovered after washing and incubating bacilli in fresh resuscitation media containing potassium. This resuscitation of growth occurred too quickly to be attributed to M. tuberculosis replication. Transcriptomic and proteomic profiling through adaptation to, and resuscitation from, this NC state revealed a switch to anaerobic respiration and a shift to lipid and amino acid metabolism. High concordance with mRNA signatures derived from M. tuberculosis infection models suggests that analogous NC mycobacterial phenotypes may exist during disease and may represent unrecognized populations in vivo. Resuscitation of NC bacilli in potassium-sufficient media was characterized by time-dependent activation of metabolic pathways in a programmed series of processes that probably transit bacilli through challenging microenvironments during infection.

  3. Potassium availability triggers Mycobacterium tuberculosis transition to, and resuscitation from, non-culturable (dormant) states

    Science.gov (United States)

    Salina, Elena G.; Waddell, Simon J.; Hoffmann, Nadine; Rosenkrands, Ida; Butcher, Philip D.; Kaprelyants, Arseny S.

    2014-01-01

    Dormancy in non-sporulating bacteria is an interesting and underexplored phenomenon with significant medical implications. In particular, latent tuberculosis may result from the maintenance of Mycobacterium tuberculosis bacilli in non-replicating states in infected individuals. Uniquely, growth of M. tuberculosis in aerobic conditions in potassium-deficient media resulted in the generation of bacilli that were non-culturable (NC) on solid media but detectable in liquid media. These bacilli were morphologically distinct and tolerant to cell-wall-targeting antimicrobials. Bacterial counts on solid media quickly recovered after washing and incubating bacilli in fresh resuscitation media containing potassium. This resuscitation of growth occurred too quickly to be attributed to M. tuberculosis replication. Transcriptomic and proteomic profiling through adaptation to, and resuscitation from, this NC state revealed a switch to anaerobic respiration and a shift to lipid and amino acid metabolism. High concordance with mRNA signatures derived from M. tuberculosis infection models suggests that analogous NC mycobacterial phenotypes may exist during disease and may represent unrecognized populations in vivo. Resuscitation of NC bacilli in potassium-sufficient media was characterized by time-dependent activation of metabolic pathways in a programmed series of processes that probably transit bacilli through challenging microenvironments during infection. PMID:25320096

  4. Communication: State-to-state dynamics of the Cl + H2O → HCl + OH reaction: Energy flow into reaction coordinate and transition-state control of product energy disposal

    International Nuclear Information System (INIS)

    Zhao, Bin; Guo, Hua; Sun, Zhigang

    2015-01-01

    Quantum state-to-state dynamics of a prototypical four-atom reaction, namely, Cl + H 2 O → HCl + OH, is investigated for the first time in full dimensionality using a transition-state wave packet method. The state-to-state reactivity and its dependence on the reactant internal excitations are analyzed and found to share many similarities both energetically and dynamically with the H + H 2 O → H 2 + OH reaction. The strong enhancement of reactivity by the H 2 O stretching vibrational excitations in both reactions is attributed to the favorable energy flow into the reaction coordinate near the transition state. On the other hand, the insensitivity of the product state distributions with regard to reactant internal excitation stems apparently from the transition-state control of product energy disposal

  5. Zero-momentum coupling induced transitions of ground states in Rashba spin-orbit coupled Bose-Einstein condensates

    Science.gov (United States)

    Jin, Jingjing; Zhang, Suying; Han, Wei

    2014-06-01

    We investigate the transitions of ground states induced by zero momentum (ZM) coupling in pseudospin-1/2 Rashba spin-orbit coupled Bose-Einstein condensates confined in a harmonic trap. In a weak harmonic trap, the condensate presents a plane wave (PW) state, a stripe state or a spin polarized ZM state, and the particle distribution of the stripe state is weighted equally at two points in the momentum space without ZM coupling. The presence of ZM coupling induces an imbalanced particle distribution in the momentum space, and leads to the decrease of the amplitude of the stripe state. When its strength exceeds a critical value, the system experiences the transition from stripe phase to PW phase. The boundary of these two phases is shifted and a new phase diagram spanned by the ZM coupling and the interatomic interactions is obtained. The presence of ZM coupling can also achieve the transition from ZM phase to PW phase. In a strong harmonic trap, the condensate exhibits a vortex lattice state without ZM coupling. For the positive effective Rabi frequency of ZM coupling, the condensate is driven from a vortex lattice state to a vortex-free lattice state and finally to a PW state with the increase of coupling strength. In addition, for the negative effective Rabi frequency, the condensate is driven from a vortex lattice state to a stripe state, and finally to a PW state. The stripe state found in the strong harmonic trap is different from that in previous works because of its nonzero superfluid velocity along the stripes. We also discuss the influences of the ZM coupling on the spin textures, and indicate that the spin textures are squeezed transversely by the ZM coupling.

  6. High-dimensional quantum key distribution with the entangled single-photon-added coherent state

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yang [Zhengzhou Information Science and Technology Institute, Zhengzhou, 450001 (China); Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Bao, Wan-Su, E-mail: 2010thzz@sina.com [Zhengzhou Information Science and Technology Institute, Zhengzhou, 450001 (China); Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Bao, Hai-Ze; Zhou, Chun; Jiang, Mu-Sheng; Li, Hong-Wei [Zhengzhou Information Science and Technology Institute, Zhengzhou, 450001 (China); Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2017-04-25

    High-dimensional quantum key distribution (HD-QKD) can generate more secure bits for one detection event so that it can achieve long distance key distribution with a high secret key capacity. In this Letter, we present a decoy state HD-QKD scheme with the entangled single-photon-added coherent state (ESPACS) source. We present two tight formulas to estimate the single-photon fraction of postselected events and Eve's Holevo information and derive lower bounds on the secret key capacity and the secret key rate of our protocol. We also present finite-key analysis for our protocol by using the Chernoff bound. Our numerical results show that our protocol using one decoy state can perform better than that of previous HD-QKD protocol with the spontaneous parametric down conversion (SPDC) using two decoy states. Moreover, when considering finite resources, the advantage is more obvious. - Highlights: • Implement the single-photon-added coherent state source into the high-dimensional quantum key distribution. • Enhance both the secret key capacity and the secret key rate compared with previous schemes. • Show an excellent performance in view of statistical fluctuations.

  7. Quantum key distribution with a single photon from a squeezed coherent state

    International Nuclear Information System (INIS)

    Matsuoka, Masahiro; Hirano, Takuya

    2003-01-01

    Squeezing of the coherent state by optical parametric amplifier is shown to efficiently produce single-photon states with reduced multiphoton probabilities compared with the weak coherent light. It can be a better source for a longer-distance quantum key distribution and also for other quantum optical experiments. The necessary condition for a secure quantum key distribution given by Brassard et al. is analyzed as functions of the coherent-state amplitude and squeeze parameter. Similarly, the rate of the gained secure bits G after error correction and privacy amplification given by Luetkenhaus is calculated. Compared with the weak coherent light, it is found that G is about ten times larger and its high level continues on about two times longer distance. By improvement of the detector efficiency it is shown that the distance extends further. Measurement of the intensity correlation function and the relation to photon antibunching are discussed for the experimental verification of the single-photon generation

  8. Effect of nanotube-length on the transport properties of single-file water molecules: transition from bidirectional to unidirectional.

    Science.gov (United States)

    Su, Jiaye; Guo, Hongxia

    2011-06-28

    We use molecular dynamics (MD) simulations to study the transport of single-file water molecules through carbon nanotubes (CNTs) with various lengths in an electric field. Most importantly, we find that even the water dipoles inside the CNT are maintained along the field direction, a large amount of water molecules can still transport against the field direction for short CNTs, leading to a low unidirectional transport efficiency (η). As the CNT length increases, the efficiency η will increase remarkably, and achieves the maximum value of 1.0 at or exceeding a critical CNT length. Consequently, the transition from bidirectional to unidirectional transport is observed and is found to be relevant to thermal fluctuations of the two reservoirs, which is explored by the interaction between water molecules inside and outside the CNT. We also find that the water flow vs CNT length follows an exponential decay of f  ∼  exp (- L/L(0)), and the average translocation time of individual water molecules yields to a power law of τ(trans)  ∼  L(υ), where L(0) and ν are constant and slightly depend on the field strength. We further compare our results with the continuous-time random-walk (CTRW) model and find that the water flow can also be described by a power law of f  ∼  L(-μ) modified from CTRW. Our results provide some new physical insights into the biased transport of single-file water molecules, which show the feasibility of using CNTs with any length to pump water in an electric field. The mechanism is important for designing efficient nanofluidic apparatuses.

  9. Electronic properties of excited states in single InAs quantum dots; Elektronische Struktur angeregter Zustaende einzelner InAs-Quantenpunkte

    Energy Technology Data Exchange (ETDEWEB)

    Warming, Till

    2009-02-20

    The application of quantum-mechanical effects in semiconductor nanostructures enables the realization of novel opto-electronic devices. Examples are given by single-photon emitters and emitters of entangled photon pairs, both being essential for quantum cryptography, or for qubit systems as needed for quantum computing. InAs/GaAs quantum dots are one of the most promising candidates for such applications. A detailed knowledge of the electronic properties of quantum dots is a prerequisite for this development. The aim of this work is an experimental access to the detailed electronic structure of the excited states in single InAs/GaAs quantum dots including few-particle effects and in particular exchange interaction. The experimental approach is micro photoluminescence excitation spectroscopy ({mu}PLE). One of the main difficulties using {mu}PLE to probe single QDs is the unambiguous assignment of the observed resonances in the spectrum to specific transitions. By comparing micro photoluminescence ({mu}PL) and {mu}PLE spectra, the identification of the main resonances becomes possible. The key is given by the fine structure of the hot trion. Excitation spectroscopy on single charged QDs enables for the first time the complete observation of a non-trivial fine structure of an excitonic complex in a QD, the hot trion. Modelling based on eight-band k.p theory in combination with a configuration interaction scheme is in excellent agreement. Therewith the simulation also enables realistic predictions on the fine structure of the ground-state exciton which is of large importance for single quantum dot devices. Theory concludes from the observed transitions that the structural symmetry of the QDs is broken. Micro photoluminescence excitation spectroscopy combined with resonantly excited micro photoluminescence enables an optical access to the single particle states of the hole without the influence of few-particle coulomb interactions. Based on this knowledge the exciton

  10. Geometric characterization of separability and entanglement in pure Gaussian states by single-mode unitary operations

    International Nuclear Information System (INIS)

    Adesso, Gerardo; Giampaolo, Salvatore M.; Illuminati, Fabrizio

    2007-01-01

    We present a geometric approach to the characterization of separability and entanglement in pure Gaussian states of an arbitrary number of modes. The analysis is performed adapting to continuous variables a formalism based on single subsystem unitary transformations that has been recently introduced to characterize separability and entanglement in pure states of qubits and qutrits [S. M. Giampaolo and F. Illuminati, Phys. Rev. A 76, 042301 (2007)]. In analogy with the finite-dimensional case, we demonstrate that the 1xM bipartite entanglement of a multimode pure Gaussian state can be quantified by the minimum squared Euclidean distance between the state itself and the set of states obtained by transforming it via suitable local symplectic (unitary) operations. This minimum distance, corresponding to a, uniquely determined, extremal local operation, defines an entanglement monotone equivalent to the entropy of entanglement, and amenable to direct experimental measurement with linear optical schemes

  11. Use of solid-state phase transitions for thermal energy storage. Final report, June 1, 1977--August 31, 1978

    Energy Technology Data Exchange (ETDEWEB)

    Leffler, A.J.; Myers, J.; Weinstein, D.

    1978-01-01

    A study has been carried out on the feasibility of using solid-state phase transitions for thermal energy storage. As part of this study a literature search was made to identify the most promising types of compounds and a synthesis program was carried out to prepare certain of these substances. In addition a large number of compounds for testing were obtained from commercial sources. All of the compounds were screened for transitions using a Perkin Elmer DSC-1B differential scanning calorimeter. From this program seven compounds were found that have transition energies from 20-30 cal/g in the temperatre range of 335-405 K. The most promising compound found is 5-norbornene-2,3-dicarboxylic acid anhydride having a transition of 22.6 cal/g at 366 K and an estimated cost of peparation of $0.40/lb..

  12. Theoretical Investigation on Single-Wall Carbon Nanotubes Doped with Nitrogen, Pyridine-Like Nitrogen Defects, and Transition Metal Atoms

    Directory of Open Access Journals (Sweden)

    Michael Mananghaya

    2012-01-01

    Full Text Available This study addresses the inherent difficulty in synthesizing single-walled carbon nanotubes (SWCNTs with uniform chirality and well-defined electronic properties through the introduction of dopants, topological defects, and intercalation of metals. Depending on the desired application, one can modify the electronic and magnetic properties of SWCNTs through an appropriate introduction of imperfections. This scheme broadens the application areas of SWCNTs. Under this motivation, we present our ongoing investigations of the following models: (i (10, 0 and (5, 5 SWCNT doped with nitrogen (CNxNT, (ii (10, 0 and (5, 5 SWCNT with pyridine-like defects (3NV-CNxNT, (iii (10, 0 SWCNT with porphyrine-like defects (4ND-CNxNT. Models (ii and (iii were chemically functionalized with 14 transition metals (TMs: Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Pd, Ag, Pt and Au. Using the spin-unrestricted density functional theory (DFT, stable configurations, deformations, formation and binding energies, the effects of the doping concentration of nitrogen, pyridine-like and porphyrine-like defects on the electronic properties were all examined. Results reveal that the electronic properties of SWCNTs show strong dependence on the concentration and configuration of nitrogen impurities, its defects, and the TMs adsorbed.

  13. Probing the magnetic ground state of single crystalline Ce3TiSb5

    Science.gov (United States)

    Matin, M.; Kulkarni, R.; Thamizhavel, A.; Dhar, S. K.; Provino, A.; Manfrinetti, P.

    2017-04-01

    Motivated by the report of superconductivity in R3TiSb5 (R  =  La and Ce) and possibly Nd3TiSb5 at  ∼4 K, we grew single crystals of La3TiSb5 and Ce3TiSb5 by the high-temperature solution method using Sn as a flux. While in both compounds we observed a superconducting transition at 3.7 K for resistivity and low-field magnetization, our data conclusively show that it arose from residual Sn flux present in the single crystals. In particular, the heat capacity data do not present any of the anomalies expected from a bulk superconducting transition. The anisotropic magnetic properties of Ce3TiSb5, crystallizing in a hexagonal P63/mcm structure, were studied in detail. We find that the Ce ions in Ce3TiSb5 form a Kondo lattice and exhibited antiferromagnetic ordering at 5.5 K with a reduced moment and a moderately normalized Sommerfeld coefficient of 598 mJ/mol K2. The characteristic single-ion Kondo energy scale was found to be  ∼8 K. The magnetization data were subjected to a crystal electric field (CEF) analysis. The experimentally observed Schottky peak in the 4f-electron heat capacity of Ce3TiSb5 was reproduced fairly well by the energy levels derived from the CEF analysis.

  14. Stretching and controlled motion of single-stranded DNA in locally heated solid-state nanopores.

    Science.gov (United States)

    Belkin, Maxim; Maffeo, Christopher; Wells, David B; Aksimentiev, Aleksei

    2013-08-27

    Practical applications of solid-state nanopores for DNA detection and sequencing require the electrophoretic motion of DNA through the nanopores to be precisely controlled. Controlling the motion of single-stranded DNA presents a particular challenge, in part because of the multitude of conformations that a DNA strand can adopt in a nanopore. Through continuum, coarse-grained and atomistic modeling, we demonstrate that local heating of the nanopore volume can be used to alter the electrophoretic mobility and conformation of single-stranded DNA. In the nanopore systems considered, the temperature near the nanopore is modulated via a nanometer-size heater element that can be radiatively switched on and off. The local enhancement of temperature produces considerable stretching of the DNA fragment confined within the nanopore. Such stretching is reversible, so that the conformation of DNA can be toggled between compact (local heating is off) and extended (local heating is on) states. The effective thermophoretic force acting on single-stranded DNA in the vicinity of the nanopore is found to be sufficiently large (4-8 pN) to affect such changes in the DNA conformation. The local heating of the nanopore volume is observed to promote single-file translocation of DNA strands at transmembrane biases as low as 10 mV, which opens new avenues for using solid-state nanopores for detection and sequencing of DNA.

  15. 48Ca(d,n)49Sc reaction at E/sub d/=20 MeV; proton single-particle states in 49Sc

    International Nuclear Information System (INIS)

    Iwasaki, Y.; Galonsky, A.; Weber, D.J.

    1980-01-01

    The 48 Ca(d,n) 49 Sc reaction has been studied at E/sub d/=20 MeV. Angular distributions of differential cross sections have been obtained for 14 transitions to states in 49 Sc up to an excitation energy of 7.1 MeV. A distorted-wave Born-approximation analysis has been made of the experimental data. With respect to states corresponding to the same proton single-particle orbital, relative values of derived spectroscopic factors are generally in good agreement with those obtained from ( 3 He,d) reaction data. There are remarkable differences between the results from the 48 Ca(d,n) 49 Sc reaction and the 48 Ca( 3 He,d) 49 Sc, however, regarding the dependence of the relative spectroscopic factors on proton single-particle orbitals

  16. Identification of predictive biomarkers of disease state in transition dairy cows.

    Science.gov (United States)

    Hailemariam, D; Mandal, R; Saleem, F; Dunn, S M; Wishart, D S; Ametaj, B N

    2014-05-01

    In dairy cows, periparturient disease states, such as metritis, mastitis, and laminitis, are leading to increasingly significant economic losses for the dairy industry. Treatments for these pathologies are often expensive, ineffective, or not cost-efficient, leading to production losses, high veterinary bills, or early culling of the cows. Early diagnosis or detection of these conditions before they manifest themselves could lower their incidence, level of morbidity, and the associated economic losses. In an effort to identify predictive biomarkers for postpartum or periparturient disease states in dairy cows, we undertook a cross-sectional and longitudinal metabolomics study to look at plasma metabolite levels of dairy cows during the transition period, before and after becoming ill with postpartum diseases. Specifically we employed a targeted quantitative metabolomics approach that uses direct flow injection mass spectrometry to track the metabolite changes in 120 different plasma metabolites. Blood plasma samples were collected from 12 dairy cows at 4 time points during the transition period (-4 and -1 wk before and 1 and 4 wk after parturition). Out of the 12 cows studied, 6 developed multiple periparturient disorders in the postcalving period, whereas the other 6 remained healthy during the entire experimental period. Multivariate data analysis (principal component analysis and partial least squares discriminant analysis) revealed a clear separation between healthy controls and diseased cows at all 4 time points. This analysis allowed us to identify several metabolites most responsible for separating the 2 groups, especially before parturition and the start of any postpartum disease. Three metabolites, carnitine, propionyl carnitine, and lysophosphatidylcholine acyl C14:0, were significantly elevated in diseased cows as compared with healthy controls as early as 4 wk before parturition, whereas 2 metabolites, phosphatidylcholine acyl-alkyl C42:4 and

  17. Cooperative single-photon subradiant states in a three-dimensional atomic array

    Energy Technology Data Exchange (ETDEWEB)

    Jen, H.H., E-mail: sappyjen@gmail.com

    2016-11-15

    We propose a complete superradiant and subradiant states that can be manipulated and prepared in a three-dimensional atomic array. These subradiant states can be realized by absorbing a single photon and imprinting the spatially-dependent phases on the atomic system. We find that the collective decay rates and associated cooperative Lamb shifts are highly dependent on the phases we manage to imprint, and the subradiant state of long lifetime can be found for various lattice spacings and atom numbers. We also investigate both optically thin and thick atomic arrays, which can serve for systematic studies of super- and sub-radiance. Our proposal offers an alternative scheme for quantum memory of light in a three-dimensional array of two-level atoms, which is applicable and potentially advantageous in quantum information processing. - Highlights: • Cooperative single-photon subradiant states in a three-dimensional atomic array. • Subradiant state manipulation via spatially-increasing phase imprinting. • Quantum storage of light in the subradiant state in two-level atoms.

  18. Single particle transfer reactions: what can they tell us about vibrational states

    International Nuclear Information System (INIS)

    Hering, W.R.

    1975-01-01

    The topic discussed concerns single particle transfer reactions (SPTR) which are, in general, used to study SP states. However, good SP states are rare objects in nature and people who try to look for them have often to settle with something less than ideal. Indeed the picture of a pure SP state is physically not even reasonable. It means that a nucleon is moving around a core nucleus which stays in its ground state: a process which one could call equivalent to elastic scattering of a nucleon which is not free but rather in a bound state. However it is shown that inelastic scattering is a very strong competitor to elastic scattering if the nucleus possesses states of high collectivity. Thus one would expect inelastic scattering to happen also while the nucleon is bound. This is a very intuitive picture of what is called the fragmentation of SP states. A final state psi sub(B) is populated by the transfer reaction A + a → B + b where psi sub(B) = α 1 phi 1 phi sub(A)(0) + α 2 phi 2 phi sub(A)(lambda). Hence the population of psi sub(B) automatically involves the collective state phi sub(A)(lambda). A discussion of how one can get information about phi sub(A)(lambda) out of the experimental data is given. (Auth.)

  19. Coal Transition in the United States. An historical case study for the project 'Coal Transitions: Research and Dialogue on the Future of Coal'

    International Nuclear Information System (INIS)

    Kok, Irem

    2017-01-01

    This is one of the 6 country case-studies commissioned to collect experience on past coal transitions. The 6 countries are: Czech Republic, the Netherlands, Poland, Spain, UK, USA. Their role in the Coal Transitions project was to provide background information for a Synthesis Report for decision makers, and provide general lessons for national project teams to take into account in developing their coal transitions pathways for the future. Over the past decade, the US started to cut down the production and the use of coal, which was affected by unfavorable market dynamics and changing federal regulatory environment. Even before the shale gas revolution and uptake of renewables diminish the use of coal in power generation, coal communities were struggling to meet ends. The regional cost differences between producing states, such as the Appalachian and the Powder River Basins, indicates that coal-impacted communities and workers have lived through the impacts of coal transition at varying magnitudes and time periods. In the period between 2014 and 2016, we have seen the crash of major US coal companies due to declining demand for US coal domestically and internationally. Furthermore, Obama administration's climate change policies negatively impacted coal-fired power plants with additional GHG emission requirements, contributing to declining domestic demand for coal. Combined with market downturn, US coal producers already struggle to pay for high operational costs and legal liabilities under bankruptcy conditions. With under-funded state budgets, coal states are also grappling with financial exposure resulting from pension, health care and reclamation liabilities of bankrupt coal companies. In 2016, former President Obama announced the Power Plus Plan to aid coal-impacted communities and workers to prepare for a low carbon future. The federal budget plan targeted diversification of local economies, funding of health and pension funds of miners and retraining for

  20. Efficient methods for finding transition states in chemical reactions: comparison of improved dimer method and partitioned rational function optimization method.

    Science.gov (United States)

    Heyden, Andreas; Bell, Alexis T; Keil, Frerich J

    2005-12-08

    A combination of interpolation methods and local saddle-point search algorithms is probably the most efficient way of finding transition states in chemical reactions. Interpolation methods such as the growing-string method and the nudged-elastic band are able to find an approximation to the minimum-energy pathway and thereby provide a good initial guess for a transition state and imaginary mode connecting both reactant and product states. Since interpolation methods employ usually just a small number of configurations and converge slowly close to the minimum-energy pathway, local methods such as partitioned rational function optimization methods using either exact or approximate Hessians or minimum-mode-following methods such as the dimer or the Lanczos method have to be used to converge to the transition state. A modification to the original dimer method proposed by [Henkelman and Jonnson J. Chem. Phys. 111, 7010 (1999)] is presented, reducing the number of gradient calculations per cycle from six to four gradients or three gradients and one energy, and significantly improves the overall performance of the algorithm on quantum-chemical potential-energy surfaces, where forces are subject to numerical noise. A comparison is made between the dimer methods and the well-established partitioned rational function optimization methods for finding transition states after the use of interpolation methods. Results for 24 different small- to medium-sized chemical reactions covering a wide range of structural types demonstrate that the improved dimer method is an efficient alternative saddle-point search algorithm on medium-sized to large systems and is often even able to find transition states when partitioned rational function optimization methods fail to converge.