7,752 research outputs found
What is the problem to which interactive multimedia is the solution?
This is something of an unusual paper. It serves as both the reason for and the result of a small number of leading academics in the field, coming together to focus on the question that serves as the title to this paper: What is the problem to which interactive multimedia is the solution? Each of the authors addresses this question from their own viewpoint, offering informed insights into the development, implementation and evaluation of multimedia. The result of their collective work was also the focus of a Western Australian Institute of Educational Research seminar, convened at Edith Cowan University on 18 October, 1994.
The question posed is deliberately rhetorical - it is asked to allow those represented here to consider what they think are the significant issues in the fast-growing field of multimedia. More directly, the question is also asked here because nobody else has considered it worth asking: for many multimedia is done because it is technically possible, not because it offers anything that is of value or provides the solution to a particular problem.
The question, then, is answered in various ways by each of the authors involved and each, in their own way, consider a range of fundamental issues concerning the nature, place and use of multimedia - both in education and in society generally. By way of an introduction, the following provides a unifying context for the various contributions made here
Measuring Electric Fields From Surface Contaminants with Neutral Atoms
In this paper we demonstrate a technique of utilizing magnetically trapped
neutral Rb-87 atoms to measure the magnitude and direction of stray electric
fields emanating from surface contaminants. We apply an alternating external
electric field that adds to (or subtracts from) the stray field in such a way
as to resonantly drive the trapped atoms into a mechanical dipole oscillation.
The growth rate of the oscillation's amplitude provides information about the
magnitude and sign of the stray field gradient. Using this measurement
technique, we are able to reconstruct the vector electric field produced by
surface contaminants. In addition, we can accurately measure the electric
fields generated from adsorbed atoms purposely placed onto the surface and
account for their systematic effects, which can plague a precision
surface-force measurement. We show that baking the substrate can reduce the
electric fields emanating from adsorbate, and that the mechanism for reduction
is likely surface diffusion, not desorption.Comment: 7 pages, 6 figures, published in Physical Review
On a generalized quantum SWAP gate
The SWAP gate plays a central role in network designs for qubit quantum computation. However, there has been a view to generalize qubit quantum computing to higher dimensional quantum systems. In this paper we construct a generalized SWAP gate using only instances of the generalized controlled-NOT gate to cyclically permute the states of d qudits for d prime
Wigner crystals in two-dimensional transition-metal dichalcogenides: Spin physics and readout
Wigner crystals are prime candidates for the realization of regular electron
lattices under minimal requirements on external control and electronics.
However, several technical challenges have prevented their detailed
experimental investigation and applications to date. We propose an
implementation of two-dimensional electron lattices for quantum simulation of
Ising spin systems based on self-assembled Wigner crystals in transition-metal
dichalcogenides. We show that these semiconductors allow for minimally invasive
all-optical detection schemes of charge ordering and total spin. For incident
light with optimally chosen beam parameters and polarization, we predict a
strong dependence of the transmitted and reflected signals on the underlying
lattice periodicity, thus revealing the charge order inherent in Wigner
crystals. At the same time, the selection rules in transition-metal
dichalcogenides provide direct access to the spin degree of freedom via Faraday
rotation measurements.Comment: 15 pages, 12 figure
Kiwi forego vison in the guidance of their nocturnal activities
We propose that the Kiwi visual system has undergone adaptive regression evolution driven by the trade-off between the relatively low rate of gain of visual information that is possible at low light levels, and the metabolic costs of extracting that information
Best practice in undertaking and reporting health technology assessments : Working Group 4 report
[Executive Summary] The aim of Working Group 4 has been to develop and disseminate best practice in undertaking and reporting assessments, and to identify needs for methodologic development. Health technology assessment (HTA) is a multidisciplinary activity that systematically examines the technical performance, safety, clinical efficacy, and effectiveness, cost, costeffectiveness, organizational implications, social consequences, legal, and ethical considerations of the application of a health technology (18). HTA activity has been continuously increasing over the last few years. Numerous HTA agencies and other institutions (termed in this report “HTA doers”) across Europe are producing an important and growing amount of HTA information. The objectives of HTA vary considerably between HTA agencies and other actors, from a strictly political decision making–oriented approach regarding advice on market licensure, coverage in benefits catalogue, or investment planning to information directed to providers or to the public. Although there seems to be broad agreement on the general elements that belong to the HTA process, and although HTA doers in Europe use similar principles (41), this is often difficult to see because of differences in language and terminology. In addition, the reporting of the findings from the assessments differs considerably. This reduces comparability and makes it difficult for those undertaking HTA assessments to integrate previous findings from other HTA doers in a subsequent evaluation of the same technology. Transparent and clear reporting is an important step toward disseminating the findings of a HTA; thus, standards that ensure high quality reporting may contribute to a wider dissemination of results. The EUR-ASSESS methodologic subgroup already proposed a framework for conducting and reporting HTA (18), which served as the basis for the current working group. New developments in the last 5 years necessitate revisiting that framework and providing a solid structure for future updates. Giving due attention to these methodologic developments, this report describes the current “best practice” in both undertaking and reporting HTA and identifies the needs for methodologic development. It concludes with specific recommendations and tools for implementing them, e.g., by providing the structure for English-language scientific summary reports and a checklist to assess the methodologic and reporting quality of HTA reports
The Relationship Between Molecular Gas Tracers and Kennicutt-Schmidt Laws
We provide a model for how Kennicutt-Schmidt (KS) laws, which describe the
correlation between star formation rate and gas surface or volume density,
depend on the molecular line chosen to trace the gas. We show that, for lines
that can be excited at low temperatures, the KS law depends on how the line
critical density compares to the median density in a galaxy's star-forming
molecular clouds. High critical density lines trace regions with similar
physical properties across galaxy types, and this produces a linear correlation
between line luminosity and star formation rate. Low critical density lines
probe regions whose properties vary across galaxies, leading to a star
formation rate that varies superlinearly with line luminosity. We show that a
simple model in which molecular clouds are treated as isothermal and homogenous
can quantitatively reproduce the observed correlations between galactic
luminosities in far infrared and in the CO(1->0) and HCN(1->0) lines, and
naturally explains why these correlations have different slopes. We predict
that IR-line luminosity correlations should change slope for galaxies in which
the median density is close to the line critical density. This prediction may
be tested by observations of lines such as HCO^+(1->0) with intermediate
critical densities, or by HCN(1->0) observations of intensely star-forming high
redshift galaxies with very high densities. Recent observations by Gao et al.
hint at just such a change in slope. We argue that deviations from linearity in
the HCN(1->0)-IR correlation at high luminosity are consistent with the
assumption of a constant star formation efficiency.Comment: Accepted to ApJ. 11 pages, 4 figures, emulateapj format. This version
has some additional models exploring the effects of varying metallicity and
temperature. The conclusions are unchange
An optimized chiral nucleon-nucleon interaction at next-to-next-to-leading order
We optimize the nucleon-nucleon interaction from chiral effective field
theory at next-to-next- to-leading order. The resulting new chiral force
NNLOopt yields \chi^2 \approx 1 per degree of freedom for laboratory energies
below approximately 125 MeV. In the A = 3, 4 nucleon systems, the contributions
of three-nucleon forces are smaller than for previous parametrizations of
chiral interactions. We use NNLOopt to study properties of key nuclei and
neutron matter, and demonstrate that many aspects of nuclear structure can be
understood in terms of this nucleon-nucleon interaction, without explicitly
invoking three-nucleon forces.Comment: 6 pages, 4 figure
Measurement of the Temperature Dependence of the Casimir-Polder Force
We report on the first measurement of a temperature dependence of the
Casimir-Polder force. This measurement was obtained by positioning a nearly
pure 87-Rb Bose-Einstein condensate a few microns from a dielectric substrate
and exciting its dipole oscillation. Changes in the collective oscillation
frequency of the magnetically trapped atoms result from spatial variations in
the surface-atom force. In our experiment, the dielectric substrate is heated
up to 605 K, while the surrounding environment is kept near room temperature
(310 K). The effect of the Casimir-Polder force is measured to be nearly 3
times larger for a 605 K substrate than for a room-temperature substrate,
showing a clear temperature dependence in agreement with theory.Comment: 4 pages, 4 figures, published in Physical Review Letter
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