720 research outputs found
Very weak electron-phonon coupling and strong strain coupling in manganites
The coupling of the manganite stripe phase to the lattice and to strain has
been investigated via transmission electron microscopy studies of
polycrystalline and thin film manganites. In polycrystalline \PCMOfiftwo a
lockin to in a sample with has been observed for the first
time. Such a lockin has been predicted as a key part of the Landau CDW theory
of the stripe phase. Thus it is possible to constrain the size of the
electron-phonon coupling in the CDW Landau theory to between 0.04% and 0.05% of
the electron-electron coupling term. In the thin film samples, films of the
same thickness grown on two different substrates exhibited different
wavevectors. The different strains present in the films on the two substrates
can be related to the wavevector observed via Landau theory. It is demonstrated
that the the elastic term which favours an incommensurate modulation has a
similar size to the coupling between the strain and the wavevector, meaning
that the coupling of strain to the superlattice is unexpectedly strong.Comment: 6 pages, 7 figure
Charge order in Fe2OBO3: An LSDA+U study
Charge ordering in the low-temperature monoclinic structure of iron oxoborate
(Fe2OBO3) is investigated using the local spin density approximation (LSDA)+U
method. While the difference between t_{2g} minority occupancies of Fe^{2+} and
Fe^{3+} cations is large and gives direct evidence for charge ordering, the
static "screening" is so effective that the total 3d charge separation is
rather small. The occupied Fe^{2+} and Fe^{3+} cations are ordered alternately
within the chain which is infinite along the a-direction. The charge order
obtained by LSDA+U is consistent with observed enlargement of the \beta angle.
An analysis of the exchange interaction parameters demonstrates the
predominance of the interribbon exchange interactions which determine the whole
L-type ferrimagnetic spin structure.Comment: 7 pages, 8 figure
How analysts think: think-steps as a tool for structuring sensemaking in criminal intelligence analysis
Sensemaking has been described as a process involving information structuring. However, there are few detailed accounts of how this manifests in practice, particularly in relation to the creation and use of external representations such as data visualisations, and how such structuring aids sensemaking. To explore these questions in depth, we present an interview study of police crime analysts from which a model of their analysis process is developed. We describe the model focusing on the notion of 'think-steps', which for the analysts acted as a primary structuring concept. We describe how 'think-steps' propagate throughout the analysis process captured in the model. For the analysts, 'think-steps' are extensible templates that decompose a case into elements, provide a way of storing and visually structuring data, support generation of requests for information, focus research, simulate a case, and shape reporting. We reflect on the implications that our findings might have for design, including the possibility of a repertoire of evolving, sharable and reusable templates for sensemaking within a community of practice
Supporting the externalisation of thinking in criminal intelligence analysis
At the end of the criminal intelligence analysis process there are relatively well established and understood approaches to explicit externalisation and representation of thought that include theories of argumentation, narrative and hybrid approaches that include both of these. However the focus of this paper is on the little understood area of how to support users in the process of arriving at such representations from an initial starting point where little is given. The work is based on theoretical considerations and some initial studies with end users. In focusing on process we discuss the requirements of fluidity and rigor and how to gain traction in investigations, the processes of thinking involved including abductive, deductive and inductive reasoning, how users may use thematic sorting in early stages of investigation and how tactile reasoning may be used to externalize and facilitate reasoning in a productive way. In the conclusion section we discuss the issues raised in this work and directions for future work
How analysts think: navigating uncertainty – aspirations, considerations and strategies
While there has been considerable research in understanding the process of sense making in criminal intelligence analysis as well as the formulation of arguments in the domain of law, there remain gaps in our understanding of how to move seamlessly from the fluidity of the sense making activities to the rigour of argumentation construction. This matter is complicated further with high uncertainty which accompanies sense making and which propagates through to the rigour that accompanies argumentation. This paper attempts to understand how Criminal Intelligence Analysts navigate uncertainty from fluidity to rigour constructs and outlines some of the considerations and strategies deployed by the Criminal Intelligence Analyst to reach, or increase, certainty at a given point in time during the analysis process. This paper concludes by proposing preliminary suggestions with the aim to narrow the gaps in this journey from fluidity to rigour, at least, marginall
How can we design tactile interactive software for argument construction in criminal intelligence analysis?
Argumentation construction refers to the different ways in which people can formulate a well defined argument that can withstand scrutiny in a court of law. Different domains have enhanced the research on argumentation construction, but each enhancement relates either to ‘evidence’ or to the ‘relevance of evidence’, thus making these elements the corner stone elements of argumentation construction. By attempting to understand how Criminal Intelligence Analysts understand and manage these corner stone elements, as well as how these elements differ to the law domain counterparts, we aspire to formulate design guidelines for a software program that is tailored to how Criminal Intelligence Analysts think and argue during sense-making activities. This paper outlines the relevant literature and why the researchers consider ‘evidence’ and the ‘relevance of evidence’ as the corner stone elements of argumentation construction. The results section summarises the outcomes of two qualitative studies. The first study aims to understand how Criminal Intelligence Analysts perceive and manage uncertain information and how this eventually leads to the creation of evidence (as exhibits) for a court of law. The second study aims to understand how Criminal Intelligence Analysts know which information is relevant for the task at hand, especially when uncertainty is high. The results of the two studies still need to be combined and put into practise (as design guidelines) to test the effectiveness and validity of the results obtained in the two studies. This is listed as future work in the conclusion section
How analysts think: how do criminal intelligence analysts recognise and manage significant information?
The Criminal Intelligence Analyst's role is to create exhibits which are relevant, accurate and unbiased. Exhibits can be used as input to assist decision-making in intelligence-led policing. It may also be used as evidence in a court of law. The aim of this study was to determine how Criminal Intelligence Analysts recognise and manage significant information as a method to determine what is relevant for their attention and for the creation of exhibits. This in turn may provide guidance on how to design and incorporate loose and flexible argumentation schemas into sense-making software. The objective is to be informed on how to design software, which affords Criminal Intelligence Analysts with the ability to effortlessly determine the relevance of information, which subsequently could assist with the process of assessing and defending the quality of exhibits
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