1,412 research outputs found
Explicit large nuclear charge limit of electronic ground states for Li, Be, B, C, N, O, F, Ne and basic aspects of the periodic table
This paper is concerned with the Schrödinger equation for atoms and ions with to 10 electrons. In the asymptotic limit of large nuclear charge , we determine explicitly the low-lying energy levels and eigenstates. The asymptotic energies and wavefunctions are in good quantitative agreement with experimental data for positive ions, and in excellent qualitative agreement even for neutral atoms (). In particular, the predicted ground state spin and angular momentum quantum numbers ( for He, Be, Ne, for H and Li, for N, for B and F, and for C and O) agree with experiment in every case. The asymptotic Schrödinger ground states agree, up to small corrections, with the semiempirical hydrogen orbital configurations developed by Bohr, Hund, and Slater to explain the periodic table. In rare cases where our results deviate from this picture, such as the ordering of the lowest and states of the carbon isoelectronic sequence, experiment confirms our predictions and not Hund's
A Study of Full Scale CMS Tracker Alignment using High Momentum Muons and Cosmics
The positions of the silicon modules of the CMS tracker will be known to m) from survey measurements, mounting precision and the laser alignment system. However, in order to fully exploit the capabilities of the tracker, these positions need to be known to a precision of a few m. Only a track-based alignment procedure can reach this required precision. Such an alignment procedure is a major challenge given that about 50000 geometry constants need to be measured. Making use of the novel minimization program Millepede II an alignment strategy has been developed in which all detector components are aligned simultaneously and all correlations between their position parameters taken into account. Different datasets, such as Z decays and cosmic muons, plus information about the mechanical structure of the tracker, and initial position uncertainties have been used as input for the alignment procedure. A proof of concept of this alignment strategy is demonstrated using simulated data
Toxicity of Nitrification Inhibitors on Dehydrogenase Activity in Soils
The objective of this research was to determine the effects of nitrification inhibitors (NIs) such as 3,4-dimethylpyrazolephosphate=DMPP, 4-Chlor-methylpyrazole phosphate=ClMPP and dicyandiamide,DCD) which might be expected to inhibit microbial activity, on dehydrogenase activity (DRA),in three different soils in laboratory conditions. Dehydrogenase activity were assessed via reduction of 2-p-Iodophenyl-3-p-nitrophenyl-5-phenyltetrazoliumchloride (INT). The toxicity and dose response curve of three NIs were quantified under laboratory conditions using a loamy clay, a sandy loam and a sandy soil. The quantitative determination of DHA was carried out spectrophotometrically. In all experiments, the influence of 5-1000 times the base concentration were examined. To evaluate the rate of inhibition with the increasing NI concentrations, dose reponse curves were presented and no observable effect level =NOEL, as well as effective dose ED10 and ED 50(10% and 50% inhibition) were calculated. The NOEL for common microbial activity such as DHA was about 30â70 times higher than base concentration in all investigated soils. ClMPP exhibited the strongest influence on the non target microbial processes in the three soils if it compare to DMPP and DCD. The NOEL,ED10 and ED50 values higher in clay than in loamy or sandy soil. The NIs were generally most effective in sandy soils. The three NIs considered at the present state of knowledge as environmentally safe in use
Efficient Algorithm for Asymptotics-Based Configuration-Interaction Methods and Electronic Structure of Transition Metal Atoms
Asymptotics-based configuration-interaction (CI) methods [G. Friesecke and B.
D. Goddard, Multiscale Model. Simul. 7, 1876 (2009)] are a class of CI methods
for atoms which reproduce, at fixed finite subspace dimension, the exact
Schr\"odinger eigenstates in the limit of fixed electron number and large
nuclear charge. Here we develop, implement, and apply to 3d transition metal
atoms an efficient and accurate algorithm for asymptotics-based CI.
Efficiency gains come from exact (symbolic) decomposition of the CI space
into irreducible symmetry subspaces at essentially linear computational cost in
the number of radial subshells with fixed angular momentum, use of reduced
density matrices in order to avoid having to store wavefunctions, and use of
Slater-type orbitals (STO's). The required Coulomb integrals for STO's are
evaluated in closed form, with the help of Hankel matrices, Fourier analysis,
and residue calculus.
Applications to 3d transition metal atoms are in good agreement with
experimental data. In particular we reproduce the anomalous magnetic moment and
orbital filling of Chromium in the otherwise regular series Ca, Sc, Ti, V, Cr.Comment: 14 pages, 1 figur
Die Verbesserung der Situation demenziell erkrankter Menschen auf dem PrĂŒfstand:Eine Vergleichsstudie zu TherapieansĂ€tzen und Versorgungsstrukturen auf der Grundlage internationaler Forschungsergebnisse
Anliegen dieser Dissertation ist es, auf der Grundlage von internationalen empirischen Studien sowohl nichtmedizinische TherapieansĂ€tze als auch neuere Versorgungssettings fĂŒr demenziell erkrankte Menschen einer Bewertung zu unterziehen. Eine solche scheint angesichts der Brisanz des Themas âDemenzâ gegenwĂ€rtig dringend geboten. Die hier durchgefĂŒhrte Wirksamkeitsanalyse ist dabei gleichermaĂen erforderlich und wichtig, fĂŒr die TherapieansĂ€tze, die sich in schneller Folge entwickeln und die Versorgungssettings, von denen nach heutigem Stand am ehesten eine Verbesserung der Lebenssituation von demenzerkrankten Menschen zu erwarten ist. Die Zielsetzung der Arbeit ist auch eine sozialpolitische: durch die Evaluation der TherapieansĂ€tze und der neueren stationĂ€ren Wohnumwelten soll ein Beitrag zur Implementierung und zum Aufbau adĂ€quater, das heiĂt insbesondere dem Anspruch der LebensqualitĂ€t verpflichteter Versorgungs- und Betreuungsstrukturen geleistet werden
Representational affordances in design, with examples from analogy making and optimization
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