1,391 research outputs found
Formation of solid Kr nanoclusters in MgO
No full textThe phenomenon of positron confinement enables us to investigate the electronic structure of nanoclusters embedded in host matrices. Solid Kr nanoclusters are a very interesting subject of investigation because of the very low predicted value of the positron affinity of bulk Kr. In this work, positron trapping in solid Kr nanoclusters embedded in MgO is investigated. The Kr nanoclusters were created by means of 280 keV Kr ion implantation in single crystals of MgO(100) and subsequent thermal annealing at a temperature of 1100 K. The nanoclusters were observed by cross-sectional transmission electron microscopy in high-resolution mode. The fcc Kr nanoclusters are rectangularly shaped with sizes of 2 to 5 nm and are in a cube-on-cube orientation relationship with the MgO host matrix. From the Moiré fringes in high-resolution recordings, the lattice parameter of the solid Kr was deduced and found to vary from 5.3 to 5.8 Å. The corresponding pressures are 0.6–2.5 GPa as found using the Ronchi equation of state. The relationship between lattice parameter and cluster size was investigated and it was found that the lattice parameter increases linearly with increasing nanocluster size. The defect evolution during annealing was monitored by means optical absorption spectroscopy and positron beam analysis. No evidence of positron trapping was found despite the very low positron affinity of solid Kr. Alternative definitions of the positron affinity are proposed for application to insulator materials.
Track Chair: Open Government Data: Policy and Politics
No full textThis is the author accepted manuscript. The final version is available from Digital Government Society via the URL in this recordIn recent decade, opening up government data and encouraging public engagement with/via data becomes an influential idea in multiple fields of public management innovation, digital economy, and international development (Janssen et al. 2012; Catlaw and Sandberg 2012; Zuiderwijk and Janssen 2014). A growing body of literature is being focused on the potential benefits for, and motivations of, governments to adopt the practice of open data in various countries as well as
international organizations (Janssen et al. 2012). Most list the main benefits by making clear reference to the universal socio-political values (such as transparency, collaboration, and participation) (OGP 2011). It has almost been assumed that open government data is one of the rare political agendas whose principle objectives reached wide-range consensus, leaving only the technical details of how-to-do largely undecided. [...
[[alternative]]The effect of KR precision within bandwidth on the learning of a spatial motor task
No full text[[abstract]]The purpose of this study was to investigate the effects of precision of knowledgeof results within bandwidth on learning a spatial motor task and its development of error detection capability. Thirty-two university female students who had no previous golf putting experience served as participants and were randomly assigned to one of following groups:(1)within BWKR group;(2)within BW and error direction of KR group;(3)within BW and error magnitude of KR group; and (4)tranditional BWKR group.Experimental trials for pretest to test the homogeneity of participants, 100practice trials for acquisition, 20 trials for 10-minute immediate retention test,and 20 trials for one-day delay retention test. Other than measuring participants' performance during acquistion and retention phases, on interviewing participants'perception of feedback information was also administered. The error(AE), vaiableerror(VE), and absolute difference between objective performance and subjective estimation(|O-S|). Two-way ANOVA with one factor repeated, Tukey's HSD method and test were used for statistical analysis. Findings were as followings:(1)different percision KR within bandwidth did not affect movement consistency; (2)BWKR in combination of both qualitative KR and qualitative KR was found beneficial for participants' movement accuracy. Both groups which were provided" qualitative KRwithin BW associated with qualitative KR outside BW" produced participants' development of error detection capability. Among it, providing qualitative within BW" had positive effects on participants' development of error detection capability.
KINETIC INVESTIGATION OF COLLISION INDUCED EXCITATION TRANSFER IN Kr() + Kr () AND Kr() + He () MIXTURES
No full textAuthor Institution: Department of Chemistry, Emory University, Atlanta, GA 30322Metastable rare gas atoms are gaining increasing interest for their potential in the development of optically pumped laser systems. Understanding the time evolution of excited rare gas states in a collisional environment is of importance for the possibility of exploiting them as the active laser species. Collisional deactivation rates for excited states of Kr() atoms colliding with ground state Kr () and He () have been measured by time resolved measurements of the laser induced fluorescence, following state selective excitation at room temperature. Collisional energy transfer for the Kr() + Kr () and Kr() + He () systems were investigated in a pulsed electrical discharge. Metastable Kr() was generated by electron impact excitation from the ground state. Using a pulsed tunable dye laser these metastable states were pumped to selected upper levels of the 2 manifold (Paschen notation) and time-dependent fluorescence decay data from pumped and collisionally populated levels were collected. The total and intramultiplet state-to-state collisional deactivation rate constants were derived from the experimental data and by numerical models. The experimental data were simulated by fitting to numerical solutions of a set of coupled differential equations describing the full collisional relaxation processes. State-to-state rate constants are reported
THE STRUCTURE OF DETERMINED FROM THE NUCLEAR QUADRUPOLE COUPLING CONSTANTS OF
No full textAuthor Institution: Department of Chemistry, University of MichiganThe nuclear quadrupole coupling constants were measured for the complex using a FTMW spectrometer. These values were compared with those expected from the Sternheimer equation for four possible structures which are consistent with the rotational constants. The value of (field gradient arising from ) for each structure was calculated using GAUSSIAN86 for free . Information on (Sternheimer shielding factor) necessary for the analysis was obtained by comparison with other complexes in the literature. The conclusion was that only one structure is consistent with the quadrupole coupling constants viz the conformation placing the Kr over a face. A comparison between ab initio calculations and a multipole expansion approximation to estimate the electric field gradient at the rare gas site in van der Waals complexes will be presented
ELECTRONIC SPECTROSCOPY AND VIBRATIONAL PREDISSOCIATION DYNAMICS OF OH/D-Kr
No full textAuthor Institution: Department of Chemistry, Emory UniversityOH/D-Kr complexes were generated in expansion driven by Ne/Kr mixtures. Bands belonging to the complexes were seen in the vicinity of the OH/D A-X 0-0 and 1-0 transitions. Despite the congestion caused by presence of several Kr isotopes, seventeen bands were rotationally resolved and analyzed. For the ground state, the zero-point rotational constant defined a Kr to OH center of mass distance of 3.780.01 \AA. The relatively small effect of H/D isotopic substitution on the ground state rotational constant was consistent with a linear hydrogen-bonded equilibrium geometry. Assignment of the A state vibrational levels was accomplished by means of the Kr isotope effect. A lower limit for the dissociation energy for of was derived from the vibrational constants. Extrapolation of the rotational constants yielded an equilibrium intermolecular separation of 2.670.12 \AA. Vibrational predissociation of OH/D(A, v=1)-Kr causes measurable line broadening in several bands. We are in the process of determining the linewidths, in order to quantify the predissociation rates. However, it is already evident that the linewidths do not show a simple dependence on internal energy, indicating the presence of novel dynamical effects. The results for OH/D-Kr will be compared and contrasted with those for OH/D-Ne and OH/D-Ar
Average-Kr Schedule Benefits Generalized Motor Program Learning
No full text The main purpose of this study was to examine the effects of average Knowledge of Results (KR) on generalized motor program learning and parameter learning. Two groups of participants ( n = 15 per group) performed 80 acquisition trials of sequential timing tasks. All participants were asked to depress sequentially four keys (2, 4, 8, and 6) on the numeric pad portion of the computer keyboard with the index finger of the right hand. The author presented average feedback on timing errors based on 5-trial blocks and compared this feedback schedule with every-trial feedback. Analysis of the delayed no-feedback retention test indicated a strong advantage for the average KR compared with the every-trial condition in both generalized motor program learning and parameter learning. The current results suggest that the average KR schedule may have positive effects on generalized motor program learning and parameter learning. </jats:p
CHEMICAL BONDING BETWEEN Ar/Kr And Au: FTMW SPECTRA, GEOMETRICS AND HYPERFINE CONSTANTS OF THE COMPLEXES Ar-AuX (X=F, Cl, Br) AND Kr-AuCl.
No full textAuthor Institution: Department of Chemistry, University of British Columbia; Departmento de Qu\'imica F\'isica, Facultad de Ciencias, Universidad de ValladolidThe microwave rotational spectra of Ar-AuX(X=F,Cl,Br) and of Kr-AuCl were measured in the 5-22 GHz range using a cavity pulsed-jet Fourier transform microwave spectrometer. All complexes were found to be linear and rather rigid. Ground slate effective () geometries were found for all complexes, white for Kr-AuCl a substitution () structure was obtained. The Ar-Au distance ranges from 2.39 to 2.50 {\AA} in going from Ar-AuF to Ar-AuBr while for Kr-AuCl, the Kr-Au distance is 2.52{\AA}. The Au nuclear quadrupole coupling constant was found to change radically on complex formation. For Ar-AuCl, MHz while for Kr-AuCl, eQq(Au)=349.7 MHz, is in contrast with that of monomeric AuCl where eQq(Au)=+9.6 MHz. Ab initio calculations at the MP2 level of theory predict a Ar-Au bond energy of for Ar-AuCl with a transfer of 0.1 electrons from Ar to Au, while for Kr-AuCl the bond energy is with a transfer of 0.2 electrons from Kr to Au. The whole picture is consistent with weak Ng-Au covalent bonding
ROTATIONAL SPECTRA OF THE and VAN DER WAALS COMPLEXES
No full textAuthor Institution: Department of Chemistry, University of AlbertaRotational spectra of the and van der Waals complexes were measured between 4 and 24 GHz using a pulsed jet cavity Fourier transform microwave spectrometer. The isotopomers studied include those of and with Ne and and with the 5 most abundant isotopes of Kr. Transitions corresponding to the internal rotor state have been measured and assigned for the Ne and Kr isotopomers and transitions related to the state have been tentatively assigned for the Kr isotopomers. The spectra of the complexes containing and showed nuclear hyperfine structure due to the quadrupole moments of the nuclei. Rotational, centrifugal distortion and quadrupole coupling constants were determined and used to calculate structural parameters
ROTATIONAL SPECTRA OF THE VAN DER WAALS COMPLEX
No full textAuthor Institution: Department of Chemistry, University of AlbertaRotational spectra of the van der Waals complex were measured between 4 and 19 GHz using a pulsed jet cavity Fourier transform microwave spectrometer. The isotopomers studied include those of , and with 6 different isotopes of Kr. Tunnelling splittings were observed for all isotopomers with the exception of Kr-HDO. Transitions of complexes with showed nuclear hyperfine structure due to the quadrupole moments of , and , respectively. Rotational and centrifugal distortion constants were determined and used to calculate structural parameters
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