2,205 research outputs found
Documenting Current Instructional Design Practices: Towards a Typology of Instructional Designer Activities, Roles, and Collaboration
The overall goal of this study was to conduct a yearlong inquiry into an instructional designer’s activities and interactions with his clients. Exclusive focus of this study was on an instructional designer who worked at a large public university in the southeastern region of the United States. Documented in an instructional design activities log, this study analyzed 115 distinct activities. Using an emergent theme analysis approach, specific instructional design activities and roles emerged. In addition, the instructional designer’s collaboration with his clients was analyzed. Results of this study augment the knowledge base of existing studies of instructional design practices
New Fe II energy levels from stellar spectra
The spectra of B-type and early A-type stars show numerous unidentified lines
in the whole optical range, especially in the 5100 - 5400 A interval. Because
Fe II transitions to high energy levels should be observed in this region, we
used semiempirical predicted wavelengths and gf-values of Fe II to identify
unknown lines. Semiempirical line data for Fe II computed by Kurucz are used to
synthesize the spectrum of the slow-rotating, Fe-overabundant CP star HR 6000.
We determined a total of 109 new 4f levels for Fe II with energies ranging from
122324 cm^-1 to 128110 cm^-1. They belong to the Fe II subconfigurations
3d^6(^3P)4f (10 levels), 3d^6(^3H)4f (36 levels), 3d^6(^3F)4f (37 levels), and
3d^6(^3G)4f (26 levels). We also found 14 even levels from 4d (3 levels), 5d (7
levels), and 6d (4 levels) configurations. The new levels have allowed us to
identify more than 50% of the previously unidentified lines of HR 6000 in the
wavelength region 3800-8000 A. Tables listing the new energy levels are given
in the paper; tables listing the spectral lines with loggf>/=-1.5 that are
transitions to the 4f energy levels are given in the Online Material. These new
levels produce 18000 lines throughout the spectrum from the ultraviolet to the
infrared.Comment: Paper accepted by A&A for publicatio
Broken-Symmetry Unrestricted Hybrid Density Functional Calculations on Nickel Dimer and Nickel Hydride
In the present work we investigate the adequacy of broken-symmetry
unrestricted density functional theory (DFT) for constructing the potential
energy curve of nickel dimer and nickel hydride, as a model for larger bare and
hydrogenated nickel cluster calculations. We use three hybrid functionals: the
popular B3LYP, Becke's newest optimized functional Becke98, and the simple
FSLYP functional (50% Hartree-Fock and 50% Slater exchange and LYP
gradient-corrected correlation functional) with two basis sets: all-electron
(AE) Wachters+f basis set and Stuttgart RSC effective core potential (ECP) and
basis set.
We find that, overall, the best agreement with experiment, comparable to that
of the high-level CASPT2, is obtained with B3LYP/AE, closely followed by
Becke98/AE and Becke98/ECP. FSLYP/AE and B3LYP/ECP give slightly worse
agreement with experiment, and FSLYP/ECP is the only method among the ones we
studied that gives an unaceptably large error, underestimating the dissociation
energy of nickel dimer by 28%, and being in the largest disagreement with the
experiment and the other theoretical predictions.Comment: 17 pages, 7 tables, 7 figures; submitted to J. Chem. Phys.;
Revtex4/LaTeX2e. v2 (8/5/04): New (and better) ECP results, without charge
density fitting (which was found to give large errors). Subtracted the
relativistic corrections from all experimental value
Measurement of excited-state transitions in cold calcium atoms by direct femtosecond frequency-comb spectroscopy
We apply direct frequency-comb spectroscopy, in combination with precision cw
spectroscopy, to measure the transition
frequency in cold calcium atoms. A 657 nm ultrastable cw laser was used to
excite atoms on the narrow ( Hz) clock transition, and the direct output of the frequency comb was
used to excite those atoms from the state to the state. The resonance of this second stage was detected by observing a
decrease in population of the ground state as a result of atoms being optically
pumped to the metastable states. The transition frequency is measured to be kHz; which is an improvement by almost four orders of magnitude over
the previously measured value. In addition, we demonstrate spectroscopy on
magnetically trapped atoms in the state.Comment: 4 pages 5 figure
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