1,133 research outputs found
Synchronous collaborative information retrieval: techniques and evaluation
Synchronous Collaborative Information Retrieval refers to
systems that support multiple users searching together at the same time in order to satisfy a shared information need. To date most SCIR systems have focussed on providing various awareness tools in order to enable collaborating users to coordinate the search task. However, requiring users to both search and coordinate the group activity may prove too demanding. On the other hand without effective coordination policies the group search may not be effective. In this paper we propose and evaluate novel system-mediated techniques for coordinating a group search. These techniques allow for an effective division of labour across the group whereby each group member can explore a subset of the search space.We also propose and evaluate techniques to support automated sharing of knowledge across searchers in SCIR, through novel collaborative and complementary relevance feedback techniques. In order to evaluate these techniques, we propose a framework for SCIR evaluation based on simulations. To populate these simulations we extract data from TREC interactive search logs. This work represent the first simulations of SCIR to date and the first such use of this TREC data
Making history: intentional capture of future memories
Lifelogging' technology makes it possible to amass digital data about every aspect of our everyday lives. Instead of focusing on such technical possibilities, here we investigate the way people compose long-term mnemonic representations of their lives. We asked 10 families to create a time capsule, a collection of objects used to trigger remembering in the distant future. Our results show that contrary to the lifelogging view, people are less interested in exhaustively digitally recording their past than in reconstructing it from carefully selected cues that are often physical objects. Time capsules were highly expressive and personal, many objects were made explicitly for inclusion, however with little object annotation. We use these findings to propose principles for designing technology that supports the active reconstruction of our future past
Properties of pattern formation and selection processes in nonequilibrium systems with external fluctuations
We extend the phase field crystal method for nonequilibrium patterning to
stochastic systems with external source where transient dynamics is essential.
It was shown that at short time scales the system manifests pattern selection
processes. These processes are studied by means of the structure function
dynamics analysis. Nonequilibrium pattern-forming transitions are analyzed by
means of numerical simulations.Comment: 15 poages, 8 figure
Microlensing by natural wormholes: theory and simulations
We provide an in depth study of the theoretical peculiarities that arise in
effective negative mass lensing, both for the case of a point mass lens and
source, and for extended source situations. We describe novel observational
signatures arising in the case of a source lensed by a negative mass. We show
that a negative mass lens produces total or partial eclipse of the source in
the umbra region and also show that the usual Shapiro time delay is replaced
with an equivalent time gain. We describe these features both theoretically, as
well as through numerical simulations. We provide negative mass microlensing
simulations for various intensity profiles and discuss the differences between
them. The light curves for microlensing events are presented and contrasted
with those due to lensing produced by normal matter. Presence or absence of
these features in the observed microlensing events can shed light on the
existence of natural wormholes in the Universe.Comment: 16 pages, 24 postscript figures (3 coloured), revtex style, submitted
to Phys. Rev.
On the Progenitors of Core-Collapse Supernovae
Theory holds that a star born with an initial mass between about 8 and 140
times the mass of the Sun will end its life through the catastrophic
gravitational collapse of its iron core to a neutron star or black hole. This
core collapse process is thought to usually be accompanied by the ejection of
the star's envelope as a supernova. This established theory is now being tested
observationally, with over three dozen core-collapse supernovae having had the
properties of their progenitor stars directly measured through the examination
of high-resolution images taken prior to the explosion. Here I review what has
been learned from these studies and briefly examine the potential impact on
stellar evolution theory, the existence of "failed supernovae", and our
understanding of the core-collapse explosion mechanism.Comment: 7 Pages, invited review accepted for publication by Astrophysics and
Space Science (special HEDLA 2010 issue
Exact multilocal renormalization on the effective action : application to the random sine Gordon model statics and non-equilibrium dynamics
We extend the exact multilocal renormalization group (RG) method to study the
flow of the effective action functional. This important physical quantity
satisfies an exact RG equation which is then expanded in multilocal components.
Integrating the nonlocal parts yields a closed exact RG equation for the local
part, to a given order in the local part. The method is illustrated on the O(N)
model by straightforwardly recovering the exponent and scaling
functions. Then it is applied to study the glass phase of the Cardy-Ostlund,
random phase sine Gordon model near the glass transition temperature. The
static correlations and equilibrium dynamical exponent are recovered and
several new results are obtained. The equilibrium two-point scaling functions
are obtained. The nonequilibrium, finite momentum, two-time response and
correlations are computed. They are shown to exhibit scaling forms,
characterized by novel exponents , as well as
universal scaling functions that we compute. The fluctuation dissipation ratio
is found to be non trivial and of the form . Analogies and
differences with pure critical models are discussed.Comment: 33 pages, RevTe
The institutional shaping of management: in the tracks of English individualism
Globalisation raises important questions about the shaping of economic action by cultural factors. This article explores the formation of what is seen by some as a prime influence on the formation of British management: individualism. Drawing on a range of historical sources, it argues for a comparative approach. In this case, the primary comparison drawn is between England and Scotland. The contention is that there is a systemic approach to authority in Scotland that can be contrasted to a personal approach in England. An examination of the careers of a number of Scottish pioneers of management suggests the roots of this systemic approach in practices of church governance. Ultimately this systemic approach was to take a secondary role to the personal approach engendered by institutions like the universities of Oxford and Cambridge, but it found more success in the different institutional context of the USA. The complexities of dealing with historical evidence are stressed, as is the value of taking a comparative approach. In this case this indicates a need to take religious practice as seriously as religious belief as a source of transferable practice. The article suggests that management should not be seen as a simple response to economic imperatives, but as shaped by the social and cultural context from which it emerges
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