211 research outputs found
Search behaviour in electronic document and records management systems: An exploratory investigation and model
Introduction. Organisations implement records management programmes and invest in electronic document and records management systems so that information can be accessed by the right person, at the right time, with the least amount of effort and cost. One of the key factors that predicts the effectiveness of these systems relates to the degree to which users successfully identify the records they wish to retrieve. In this paper we offer a deeper insight into how knowledge workers employ these systems to address their information needs. Method. Four records managers were interviewed to determine how records management principles were applied in their systems. Interviews were also conducted with ten users from each organisation to map their search behaviour. Additionally, protocol analysis was used to observe how participants verbalised their thought processes and actions when they conducted their simple and difficult searches in the systems. Results. A comprehensive model of search behaviour when using electronic document and records management systems was developed from the study. Seven key search stages were identified, illustrating the different ways in which searchers approach their information problem. Conclusions. The study highlights some key differences between users of these systems and other forms of information search behaviour, including different methods of addressing simple or difficult search needs, and user approaches around identifying search strategies. The particular challenges that arise in retrieving information from these systems are also explored
Subthreshold K+ production in deuteron and alpha induced nuclear reactions
Double differential cross sections have been measured for pi+ and K+ emitted
around midraidity in d+A and He+A collisions at a beam kinetic energy of 1.15
GeV/nucleon. The total pi+ yield increases by a factor of about 2 when using an
alpha projectile instead of a deuteron whereas the K+ yield increases by a
factor of about 4. According to transport calculations, the K+ enhancement
depends both on the number of hadron-hadron collisions and on the energy
available in those collisions: their center-of-mass energy increases with
increasing number of projectile nucleons
Production of Charged Pions, Kaons and Antikaons in Relativistic C+C and C+Au Collisions
Production cross sections of charged pions, kaons and antikaons have been
measured in C+C and C+Au collisions at beam energies of 1.0 and 1.8 AGeV for
different polar emission angles. The kaon and antikaon energy spectra can be
described by Boltzmann distributions whereas the pion spectra exhibit an
additional enhancement at low energies. The pion multiplicity per participating
nucleon M(pi+)/A_part is a factor of about 3 smaller in C+Au than in C+C
collisions at 1.0 AGeV whereas it differs only little for the C and the Au
target at a beam energy of 1.8 AGeV. The K+ multiplicities per participating
nucleon M(K+)/A_part are independent of the target size at 1 AGeV and at 1.8
AGeV. The K- multiplicity per participating nucleon M(K-)/A_part is reduced by
a factor of about 2 in C+Au as compared to C+C collisions at 1.8 AGeV. This
effect might be caused by the absorption of antikaons in the heavy target
nucleus. Transport model calculations underestimate the K-/K+ ratio for C+C
collisions at 1.8 AGeV by a factor of about 4 if in-medium modifications of K
mesons are neglected.Comment: 19 pages, 14 figures, accepted for publication in Eur. Phys. J.
Evidence for a Soft Nuclear Equation-of-State from Kaon Production in Heavy Ion Collisions
The production of pions and kaons has been measured in Au+Au collisions at
beam energies from 0.6 to 1.5 AGeV with the Kaon Spectrometer at SIS/GSI. The
K+ meson multiplicity per nucleon is enhanced in Au+Au collisions by factors up
to 6 relative to C+C reactions whereas the corresponding pion ratio is reduced.
The ratio of the K+ meson excitation functions for Au+Au and C+C collisions
increases with decreasing beam energy. This behavior is expected for a soft
nuclear equation-of-state.Comment: 14 pages, 2 figures, accepted for publication in Phys. Rev. Let
Enhanced Out-of-plane Emission of K+ Mesons observed in Au+Au Collisions at 1 AGeV
The azimuthal angular distribution of K+ mesons has been measured in Au + Au
collisions at 1 AGeV. In peripheral and semi-central collisions, K+ mesons
preferentially are emitted perpendicular to the reaction plane. The strength of
the azimuthal anisotropy of K+ emission is comparable to the one of pions. No
in-plane flow was found for K+ mesons near projectile and target rapidity.Comment: Accepted for publication in Phys. Rev.Let
Statistical Signatures of Structural Organization: The case of long memory in renewal processes
Identifying and quantifying memory are often critical steps in developing a
mechanistic understanding of stochastic processes. These are particularly
challenging and necessary when exploring processes that exhibit long-range
correlations. The most common signatures employed rely on second-order temporal
statistics and lead, for example, to identifying long memory in processes with
power-law autocorrelation function and Hurst exponent greater than .
However, most stochastic processes hide their memory in higher-order temporal
correlations. Information measures---specifically, divergences in the mutual
information between a process' past and future (excess entropy) and minimal
predictive memory stored in a process' causal states (statistical
complexity)---provide a different way to identify long memory in processes with
higher-order temporal correlations. However, there are no ergodic stationary
processes with infinite excess entropy for which information measures have been
compared to autocorrelation functions and Hurst exponents. Here, we show that
fractal renewal processes---those with interevent distribution tails ---exhibit long memory via a phase transition at .
Excess entropy diverges only there and statistical complexity diverges there
and for all . When these processes do have power-law
autocorrelation function and Hurst exponent greater than , they do not
have divergent excess entropy. This analysis breaks the intuitive association
between these different quantifications of memory. We hope that the methods
used here, based on causal states, provide some guide as to how to construct
and analyze other long memory processes.Comment: 13 pages, 2 figures, 3 appendixes;
http://csc.ucdavis.edu/~cmg/compmech/pubs/lrmrp.ht
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