62,872 research outputs found
Concept-based Analysis of Surface and Structural Misfits (CASSM) Tutorial notes
Concept-based Analysis of Surface and Structural Misfits (CASSM) in a novel approach to usability analysis that focuses attention on misfits between user and system concepts. We believe that as an approach it has several desirable qualities: o It focuses on concepts rather than tasks or procedures. Consequently, it complements the majority of existing approaches to usability evaluation. In particular, it analyses conceptual misfits between user and system. o By intentionally supporting âsketchyâ analysis, CASSM avoids the âdeath by detailâ that plagues many evaluation techniques. CASSM analyses do not have to be complete or consistent to be useful â though of course a thorough analysis is likely to have these properties. Also, CASSM analyses are often quite succinct, compared to (for example) a Cognitive Walkthrough (Wharton et al, 1994), Heuristic Evaluation (Nielsen, 1994) or GOMS analysis (John & Kieras, 1996). o As a notation, it provides a âbridgeâ between the core ideas underpinning work on mental models and design issues, and may thus make prior work on mental models more readily accessible to design practice. [This should be regarded as a hypothesis that has not yet been tested.] o The CASSM notation provides a relatively formal definition of many of Greenâs Cognitive Dimensions (see, for example, Green, 1989; Green & Petre, 1996; Blackwell & Green 2003). In this way, it further supports assessment of a system in terms of CDs. This is discussed in detail towards the end of this document. Although the name (CASSM: Concept-based Analysis of Surface and Structural Misfits) emphasises the importance of misfits, you should be aware that there are other kinds of userâsystem misfits that are outside the scope of CASSM; for example, inconsistencies in procedures for similar tasks would be picked up by other techniques but are not directly addressed within CASSM. CASSM focuses on conceptual structures
Gravity as elasticity of spacetime: a paradigm to understand horizon thermodynamics and cosmological constant
It is very likely that the quantum description of spacetime is quite
different from what we perceive at large scales, . The
long wave length description of spacetime, based on Einstein's equations, is
similar to the description of a continuum solid made of a large number of
microscopic degrees of freedom. This paradigm provides a novel interpretation
of coordinate transformations as deformations of "spacetime solid" and allows
one to obtain Einstein's equations as a consistency condition in the long
wavelength limit. The entropy contributed by the microscopic degrees of freedom
reduces to a pure surface contribution when Einstein's equations are satisfied.
The horizons arises as "defects" in the "spacetime solid" (in the sense of well
defined singular points) and contributes an entropy which is one quarter of the
horizon area. Finally, the response of the microstructure to vacuum energy
leads to a near cancellation of the cosmological constant, leaving behind a
tiny fluctuation which matches with the observed value.Comment: This essay received an ``honorable mention'' in the 2004 Essay
Competition of the Gravity Research Foundation; accepted for publication in
IJMP
The Molonglo Galactic Plane Survey (MGPS-2): Compact Source Catalogue
We present the first data release from the second epoch Molonglo Galactic
Plane Survey (MGPS-2). MGPS-2 was carried out with the Molonglo Observatory
Synthesis Telescope at a frequency of 843 MHz and with a restoring beam of 45
arcsec x 45 arcsec cosec(dec), making it the highest resolution large scale
radio survey of the southern Galactic plane. It covers the range |b| < 10 deg
and 245 deg < l < 365 deg and is the Galactic counterpart to the Sydney
University Molonglo Sky Survey (SUMSS) which covers the whole southern sky with
dec 10 deg).
In this paper we present the MGPS-2 compact source catalogue. The catalogue
has 48,850 sources above a limiting peak brightness of 10 mJy/beam. Positions
in the catalogue are accurate to 1 arcsec - 2 arcsec. A full catalogue
including extended sources is in preparation. We have carried out an analysis
of the compact source density across the Galactic plane and find that the
source density is not statistically higher than the density expected from the
extragalactic source density alone.
We also present version 2.0 of the SUMSS image data and catalogue which are
now available online. The data consists of 629 4.3 deg x 4.3 deg mosaic images
covering the 8100 deg^2 of sky with dec 10 deg. The
catalogue contains 210,412 radio sources to a limiting peak brightness of 6
mJy/beam at dec -50 deg. We describe the
updates and improvements made to the SUMSS cataloguing process.Comment: 12 pages, 9 figures, to be published in MNRAS Note that Figures 8 and
9 are much lower resolution than in the published versio
Gold etching for microfabrication
The etching of gold is a key enabling technology in the fabrication of many microdevices and is widely used in the electronic, optoelectronic and microelectromechanical systems (MEMS) industries. In this review, we examine some of the available methods for patterning gold thin films using dry and wet etching techniques. Dry methods which utilise reactive ion etching (RIE) have a number of important advantages over other methods, but the low volatility of gold etch products has made the development of suitable processes problematic. More recently, the adoption of high-density plasma reactors with optimised chlorine-based chemistries has allowed improved processes to be developed, and etching in hydrogen plasmas also shows promise. Wet etching methods for gold have also been critically reviewed. Traditionally, iodine- and cyanide-based etch processes have been used, but in the last decade, a number of alternative etchants have been studied. Of particular interest is the recent development of a range of novel non-aqueous-based gold etchants, and the suitability of these etchants for microfabrication is assessed
A digitalized solar ultraviolet spectrum
Digitalized solar ultraviolet spectrum obtained in rocket experiments for use in analysis of upper atmosphere experiment
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