15,024 research outputs found
SCRIPTKELL : a tool for measuring cognitive effort and time processing in writing and other complex cognitive activities
We present SCRIPTKELL, a computer-assisted experimental tool that makes it possible to measure the time and cognitive effort allocated to the subprocesses of writing and other cognitive activities, SCRIPTKELL was designed to easily use and modulate Kellogg's (1986) triple-task procedure,.which consists of a combination of three tasks: a writing task (or another task), a reaction time task (auditory signal detection), and a directed retrospection task (after each signal detection during writing). We demonstrate how this tool can be used to address several novel empirical and theoretical issues. In sum, SCRIPTKELL should facilitate the flexible realization of experimental designs and the investigation of critical issues concerning the functional characteristics of complex cognitive activities
Interacting bosons in an optical lattice: Bose-Einstein condensates and Mott insulator
A dense Bose gas with hard-core interaction is considered in an optical
lattice. We study the phase diagram in terms of a special mean-field theory
that describes a Bose-Einstein condensate and a Mott insulator with a single
particle per lattice site for zero as well as for non-zero temperatures. We
calculate the densities, the excitation spectrum and the static structure
factor for each of these phases.Comment: 17 pages, 5 figures; 1 figure added, typos remove
The reaction 13C(alpha,n)16O: a background for the observation of geo-neutrinos
The absolute cross section of the C(,n)O reaction has
been measured at E = 0.8 to 8.0 MeV with an overall accuracy of 4%.
The precision is needed to subtract reliably a background in the observation of
geo-neutrinos, e.g. in the KamLAND detector.Comment: LaTex file, 13 pages including 3 ps figures. Any request to
[email protected]. Phys. Rev . C, to appea
Quantum phases in mixtures of fermionic atoms
A mixture of spin-polarized light and heavy fermionic atoms on a finite size
2D optical lattice is considered at various temperatures and values of the
coupling between the two atomic species. In the case, where the heavy atoms are
immobile in comparison to the light atoms, this system can be seen as a
correlated binary alloy related to the Falicov-Kimball model. The heavy atoms
represent a scattering environment for the light atoms. The distributions of
the binary alloy are discussed in terms of strong- and weak-coupling
expansions. We further present numerical results for the intermediate
interaction regime and for the density of states of the light particles. The
numerical approach is based on a combination of a Monte-Carlo simulation and an
exact diagonalization method. We find that the scattering by the correlated
heavy atoms can open a gap in the spectrum of the light atoms, either for
strong interaction or small temperatures.Comment: 15 pages, 8 figure
Investigation of ion induced bending mechanism for nanostructures
Ion induced bending is a promising controlled technique for manipulating nanoscale structures. However, the underlying mechanism of the process is not well understood. In this letter, we report a detailed study of the bending mechanism of Si nanowires (NWs) under Ga+ irradiation. The microstructural changes in the NW due to ion beam irradiation are studied and molecular dynamics simulations are used to explore the ion–NW interaction processes. The simulation results are compared with the microstructural studies of the NW. The investigations inform a generic understanding of the bending process in crystalline materials, which we suggest to be feasible as a versatile manipulation and integration technique in nanotechnology
Analysis of Pregnancy and Other Factors on Detection of Human Papilloma Virus (HPV) Infection Using Weighted Estimating Equations for Follow-Up Data
Generalised estimating equations have been well established to draw inference for the marginal mean from follow-up data. Many studies suffer from missing data that may result in biased parameter estimates if the data are not missing completely at random. Robins and coworkers proposed to use weighted estimating equations (WEE) in estimating the mean structure if drop-out occurs missing at random. We illustrate the differences between the WEE and the commonly applied available case analysis in a simulation study. We apply the WEE and re-analyse data on pregnancy and HPV infection. We estimate the response probabilities and demonstrate that the data are not missing completely at random. Upon use of the WEE, we are able to show that pregnant women have an increased odds for an HPV infection compared with study subjects after delivery (p = 0.027). We conclude that the WEE are useful in analysing follow-up data with drop-outs
Density of states "width parity" effect in d-wave superconducting quantum wires
We calculate the density of states (DOS) in a clean mesoscopic d-wave
superconducting quantum wire, i.e. a sample of infinite length but finite width
. For open boundary conditions, the DOS at zero energy is found to be zero
if is even, and nonzero if is odd. At finite chemical potential, all
chains are gapped but the qualtitative differences between even and odd
remain.Comment: 7 pages, 8 figures, new figures and extended discussio
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