-bilities. In this paper, we propose a method for target iden-tification with a heterogeneous swarm of low-informative spatially-distributed sensors employing a distributed version of the naive Bayes classifier. Despite limited individual sens-ing capabilities, the recursive application of the Bayes law allows

Together, the TREC Very Large Collection (VLC) Track and its successor the Web Track have run for seven years, after an initial VLC pre-track. During that time five new test collections have been created, five different types of retrieval task have been studied, a large number of important issues have been addressed, and new methods have been tried, not only for retrieval, but also for test collection

Abstract. Whiteboards are highly important to the work in emergency departments (EDs). As a collaborative technology ED whiteboards are usually placed in the dynamic centre of the ED, and all ED staff will approach the whiteboard regularly to organize their individual yet interdependent work. Currently, digital whiteboards are replacing the ordinary dry-erase whiteboards in EDs, which bring the design and use of whiteboards in ED to our attention. Previous studies have applied the theoretical lenses of common information spaces, coordination, and awareness to the investigation of whiteboard use and design. Based on an ethnographic study of the work practices involving two differently designed ED whiteboards, we found these concepts insufficient to explain one essential characteristic of these heterogeneous artefacts. In this paper, we suggest an additional theoretical concept describing this characteristic of heterogeneous artefacts; namely artefactual multiplicity. Artefactual multiplicity identifies not only the multiple functions of heterogeneous artefacts but also the intricate relations between these multiple functionalities.

Passwords are a widely used mechanism for user authentication and thus critical to the security of many systems. To provide effective security, passwords should be known to the password holder but remain unknown to everybody else. While personal information and real words are relatively easy for a user to remember they make weak passwords from a security point of view because they are vulnerable to informed guessing and dictionary attacks. Strong passwords (e.g., b5j#Kv!8N) are less vulnerable to attack but at the same time more difficult to remember. However, the sheer number of passwords people must have to accomplish their day-to-day activities exceeds most humans ’ capacity for remembering meaningless strings of characters [1]. Most users handle the ensuing conflict between security and ease of use by choosing passwords that are easy to remember, writing down their passwords, using the same password for multiple systems, or in other ways giving ease of use priority over security. Minimal-feedback hints are introduced to support users in remembering their passwords and thereby enable them to choose stronger passwords. Whereas most password mechanisms leave it entirely to users to be able to remember their passwords, minimal-feedback hints aid users ’ memory by providing them with a couple of the password characters when prompted for their password, see Figure 1. Minimal-feedback hints were first suggested by Lu and Twidale [3] with the thinking that “a few carefully revealed hints will jog an authorized user’s memory, but will be of insufficient help to an unauthorized user who does not know the password in the first place”.

Documents are used extensively by professionals in their execution of their own work and to share information with others. Professionals use and manage their documents in ways that are woven into their work activities and leave most of the context unsaid because the documents are understood as belonging to a certain ongoing activity. Contrary to this, organisations have a strong interest in storing information in less persondependent ways than simply relying on their employees ’ memory and personal files. To support document management effectively we need to balance the individual professionals ’ focus on their current activities against the long-term interests of the organisation, and we need a fuller understanding of the affordances and constraints of documents. This study identifies six roles documents play in professionals ’ work, namely that documents serve: (1) as personal work files, (2) as reminders of things to do, (3) to share information with some yet withhold it from others, (4) to convey meaning, (5) to generate new meaning, and (6) to mediate contacts among people. Painstakingly standardised and very time-consuming methods are required for documents to convey meaning but such efforts are rarely considered worthwhile compared to relying on other document roles or rework. 1.

Abstract This paper introduces a pattern for almost compositional functionsover recursive data types, and over families of mutually recursive

In this paper, a family of kurtosis orderings for multivariate distributions is pro-posed and studied. Each ordering characterizes in an a ¢ ne invariant sense the move-ment of probability mass from the "shoulders " of a distribution to either the center or the tails or both. All even moments of the Mahalanobis distance of a random vector from its mean (if exists) preserve a subfamily of the orderings. For elliptically symmet-ric distributions, each ordering determines the distributions up to a ¢ ne equivalence. As applications, the orderings are used to study elliptically symmetric distributions. Ordering results are established for three important families of elliptically symmetric distributions: Kotz type distributions, Pearson Type VII distributions, and Pearson

Abstract—We develop a theory of algebraic operations over linear and context-free grammars that makes it possible to combine simple “atomic ” grammars operating on single sequences into complex, multi-dimensional grammars. We demonstrate the utility of this framework by constructing the search spaces of complex alignment problems on multiple input sequences explicitly as algebraic expressions of very simple 1-dimensional grammars. In particular, we provide a fully worked frameshift-aware, semiglobal DNA-protein alignment algorithm whose grammar is composed of products of small, atomic grammars. The compiler accompanying our theory makes it easy to experiment with the combination of multiple grammars and different operations. Composite grammars can be written out in LATEX for documentation and as a guide to implementation of dynamic programming algorithms. An embedding in Haskell as a domain-specific language makes the theory directly accessible to writing and using grammar products without the detour of an external compiler.

Access for independents to retail gas markets was a central concern in European policy reform efforts in the 1990s. Upstream oil and gas companies reacted with strategic intentions of forward integration. By late 2004, forward integration was still weak, however. An important explanation of the gap between announced strategic re-orientation and actual strategy implementation lies in the political failure of EU member states to dismantle market barriers to entry for independents. Variations between companies in downstream strategy implementation are explained by variations in business opportunities and internal company factors.

Abstract. Rings are assumed to be commutative. Recent work gives some of the tools needed to characterize clean, almost clean, weakly clean and uniquely clean rings by describing their Pierce sheaves. The sheaf descriptions are used to show that weakly clean and almost clean rings which are pm rings are clean. A subclass of clean rings, here called J-clean rings, also known as F-semiperfect rings, is studied. It includes the uniquely clean rings. There is a mono-functor from commutative rings to J-clean rings which satisfies a universal property. Earlier non-functorial ways of embedding rings in J-clean rings can be derived from the functor. Applications to rings of continuous functions are found throughout. 1. Definitions and preliminaries. 1.1. Introduction. Throughout “ring ” will mean a commutative ring with 1 except in the first part of Section 4 where general unitary rings will make an appearance. Various authors have studied clean rings and related conditions. The following definition is a composite.