Parallelism in the SPI algorithm : an investigation

The Symbolic Probabilistic Inference (SPI) algorithm was developed by Bruce D' Ambrosio for efficient calculation of prior probabilities in belief nets [2]. Although the complexity of the SPI algorithm compares favorably with other approaches to probabilistic inference [5], its actual running time is still prohibitively long even for moderately sized nets. As part of our overall research goal of developing decision- theoretic problem solving programs for real world real-time problems, we undertook this investigation into the feasibility of developing a parallel version of the SPI algorithm. The specific goals of this project were the following: 1. Identify those operations in the SPI algorithm that, if performed in parallel, would lead to some improvement in performance. 2. Estimate the performance of actual parallel implementations of SPI on both shared memory and cube architectures. 3. Perform a preliminary exploration into the practical issues related to developing a parallel algorithm. To accomplish these goals the following tasks were performed : 1. Examined the algorithm to identify potentially parallelizable constructs and data dependencies. 2. Designed and implemented models to simulate running the SPI algorithm in parallel. 3. Ran the models on test nets under various parameter settings simulating shared memory and cube architectures and various computational grainsizes. 4. Gathered and analyzed the test results. The remainder of the paper is organized as follows. Chapter 2 provides the necessary background information for understanding the SPI algorithm, including an overview of belief nets and an example of inference in SPI. Chapter 3 explores the sources of parallelism in the SPI algorithm. Chapter 4 describes our approach to estimating the performance of parallel versions of the SPI algorithm. Chapter 5 presents the results from simulated runs of a parallel SPI algorithm. Finally Chapter 6 includes a brief discussion of the results of this project and introduces some issues for future research

Monitoring wild animal communities with arrays of motion sensitive camera traps

Studying animal movement and distribution is of critical importance to addressing environmental challenges including invasive species, infectious diseases, climate and land-use change. Motion sensitive camera traps offer a visual sensor to record the presence of a broad range of species providing location -specific information on movement and behavior. Modern digital camera traps that record video present new analytical opportunities, but also new data management challenges. This paper describes our experience with a terrestrial animal monitoring system at Barro Colorado Island, Panama. Our camera network captured the spatio-temporal dynamics of terrestrial bird and mammal activity at the site - data relevant to immediate science questions, and long-term conservation issues. We believe that the experience gained and lessons learned during our year long deployment and testing of the camera traps as well as the developed solutions are applicable to broader sensor network applications and are valuable for the advancement of the sensor network research. We suggest that the continued development of these hardware, software, and analytical tools, in concert, offer an exciting sensor-network solution to monitoring of animal populations which could realistically scale over larger areas and time spans

A business model perspective for ICTs in public engagement

This is the post-print version of the Article. The official published article can be accessed from the link below - Copyright @ 2012 ElsevierPublic institutions, in their efforts to promote meaningful citizen engagement, are increasingly looking at the democratic potential of Information and Communication Technologies (ICTs). Previous studies suggest that such initiatives seem to be impeded by socio-technical integration barriers such as low sustainability, poor citizen acceptance, coordination difficulties, lack of understanding and failure to assess their impact. Motivated by these shortcomings, the paper develops and applies a business model perspective as an interceding framework for analysis and evaluation. The underlying principle behind this approach is that it is not technology per se which determines success, but rather the way in which the businessmodel of the technological artifact is configured and employed to achieve the strategic goals. The business model perspective is empirically demonstrated with the case of an online petitioning system implemented by a UK local authority. The case illustrates the importance of considering ICTs in public engagement from a holistic view to make them more manageable and assessable

Developmental pathways to autism: a review of prospective studies of infants at risk

Autism Spectrum Disorders (ASDs) are neurodevelopmental disorders characterized by impairments in social interaction and communication, and the presence of restrictive and repetitive behaviors. Symptoms of ASD likely emerge from a complex interaction between pre-existing neurodevelopmental vulnerabilities and the child's environment, modified by compensatory skills and protective factors. Prospective studies of infants at high familial risk for ASD (who have an older sibling with a diagnosis) are beginning to characterize these developmental pathways to the emergence of clinical symptoms. Here, we review the range of behavioral and neurocognitive markers for later ASD that have been identified in high-risk infants in the first years of life. We discuss theoretical implications of emerging patterns, and identify key directions for future work, including potential resolutions to several methodological challenges for the field. Mapping how ASD unfolds from birth is critical to our understanding of the developmental mechanisms underlying this disorder. A more nuanced understanding of developmental pathways to ASD will help us not only to identify children who need early intervention, but also to improve the range of interventions available to them

The Iceland Microcontinent and a continental Greenland-Iceland-Faroe Ridge

The breakup of Laurasia to form the Northeast Atlantic Realm was the culmination of a long period of tectonic unrest extending back to the Late Palaeozoic. Breakup was prolonged and complex and disintegrated an inhomogeneous collage of cratons sutured by cross-cutting orogens. Volcanic rifted margins formed, which are blanketed by lavas and underlain variously by magma-inflated, extended continental crust and mafic high-velocity lower crust of ambiguous and probably partly continental provenance. New rifts formed by diachronous propagation along old zones of weakness. North of the Greenland-Iceland-Faroe Ridge the newly forming rift propagated south along the Caledonian suture. South of the Greenland-Iceland-Faroe Ridge it propagated north through the North Atlantic Craton along an axis displaced ~ 150 km to the west of the northern rift. Both propagators stalled where the confluence of the Nagssugtoqidian and Caledonian orogens formed a transverse barrier. Thereafter, the ~ 400-km-wide latitudinal zone between the stalled rift tips extended in a distributed, unstable manner along multiple axes of extension that frequently migrated or jumped laterally with shearing occurring between them in diffuse transfer zones. This style of deformation continues to the present day. It is the surface expression of underlying magma-assisted stretching of ductile mid- and lower continental crust which comprises the Icelandic-type lower crust that underlies the Greenland-Iceland-Faroe Ridge. This, and probably also one or more full-crustal-thickness microcontinents incorporated in the Ridge, are capped by surface lavas. The Greenland-Iceland-Faroe Ridge thus has a similar structure to some zones of seaward-dipping reflectors. The contemporaneous melt layer corresponds to the 3–10 km thick Icelandic-type upper crust plus magma emplaced in the ~ 10–30-km-thick Icelandic-type lower crust. This model can account for seismic and gravity data that are inconsistent with a gabbroic composition for Icelandic-type lower crust, and petrological data that show no reasonable temperature or source composition could generate the full ~ 40-km thickness of Icelandic-type crust observed. Numerical modeling confirms that extension of the continental crust can continue for many tens of Myr by lower-crustal flow from beneath the adjacent continents. Petrological estimates of the maximum potential temperature of the source of Icelandic lavas are up to 1450 °C, no more than ~ 100 °C hotter than MORB source. The geochemistry is compatible with a source comprising hydrous peridotite/pyroxenite with a component of continental mid- and lower crust. The fusible petrology, high source volatile contents, and frequent formation of new rifts can account for the true ~ 15–20 km melt thickness at the moderate temperatures observed. A continuous swathe of magma-inflated continental material beneath the 1200-km-wide Greenland-Iceland-Faroe Ridge implies that full continental breakup has not yet occurred at this latitude. Ongoing tectonic instability on the Ridge is manifest in long-term tectonic disequilibrium on the adjacent rifted margins and on the Reykjanes Ridge, where southerly migrating propagators that initiate at Iceland are associated with diachronous swathes of unusually thick oceanic crust. Magmatic volumes in the NE Atlantic Realm have likely been overestimated and the concept of a monogenetic North Atlantic Igneous Province needs to be reappraised. A model of complex, piecemeal breakup controlled by pre-existing structures that produces anomalous volcanism at barriers to rift propagation and distributes continental material in the growing oceans fits other oceanic regions including the Davis Strait and the South Atlantic and West Indian oceans

NSDL Annual Report 2005: Grade Level Analysis of Eisenhower National Clearinghouse documents

As students advance to higher grade levels, they learn new words. The documents intended for upper grade levels will contain more advanced vocabularies, reflecting the assumed aptitude level of the intended audience. In this study, we first classified all the words in a pre-labeled document collection into various grade level categories. We then calculated the distribution of words from each grade level for all the documents. The eventual goal of our study is to build a system that automatically assigns the appropriate grade level label to each document in the NSDL repository. This will allow the educators to search more easily for material appropriate to specific audiences. The available dataset for this study comes from the Eisenhower National Clearinghouse. This dataset contains a total of 8,417 documents with labels specifying the intended grade levels

The Alternative Media Handbook

'Alternative Media' is the term used to describe non-mainstream media forms that are independently run and community focussed, such as zines, pirate radio, online discussion boards, community run and owned broadcasting companies, and activist publications such as Red Pepper and Corporate Watch. The book outlines the different types of 'alternative media' and offers an overview of global alternative media activity, before moving on to provide information about alternative media production and how to get involved in it, including: What is Alternative Media? alternative media in practice making media getting involved. This book will primarily appeal to students studying media freedom, alternative media, media globalization and media production as well as anyone wishing to embark on a career in this fiel

Mining IC Test Data to Optimize VLSI Testing

We describe an application of data mining and decision analysis to the problem of die-level functional test in integrated circuit manufacturing. Integrated circuits are fabricated on large wafers that can hold hundreds of individual chips (“die”). In current practice, large and expensive machines test each of these die to check that they are functioning properly (die-level functional test; DLFT), and then the wafers are cut up, and the good die are assembled into packages and connected to the package pins. Finally, the resulting packages are tested to ensure that the final product is functioning correctly. The purpose of die-level functional test is to avoid the expense of packaging bad die and to provide rapid feedback to the fabrication process by detecting die failures. The challenge for a decision-theoretic approach is to reduce the amount of DLFT (and the associated costs) while still providing process feedback. We describe a decision-theoretic approach to DLFT in which historical test data is mined to create a probabilistic model of patterns of die failure. This model is combined with greedy value-of-information computations to decide in real time which die to test next and when to stop testing. We report the results of several experiments that demonstrate the ability of this procedure to make good testing decisions, good stopping decisions, and to detect anomalous die. Based on experiments with historical test data from Hewlett Packard Company, the resulting system has the potential t