14,512 research outputs found

    Multi-scale Orderless Pooling of Deep Convolutional Activation Features

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    Deep convolutional neural networks (CNN) have shown their promise as a universal representation for recognition. However, global CNN activations lack geometric invariance, which limits their robustness for classification and matching of highly variable scenes. To improve the invariance of CNN activations without degrading their discriminative power, this paper presents a simple but effective scheme called multi-scale orderless pooling (MOP-CNN). This scheme extracts CNN activations for local patches at multiple scale levels, performs orderless VLAD pooling of these activations at each level separately, and concatenates the result. The resulting MOP-CNN representation can be used as a generic feature for either supervised or unsupervised recognition tasks, from image classification to instance-level retrieval; it consistently outperforms global CNN activations without requiring any joint training of prediction layers for a particular target dataset. In absolute terms, it achieves state-of-the-art results on the challenging SUN397 and MIT Indoor Scenes classification datasets, and competitive results on ILSVRC2012/2013 classification and INRIA Holidays retrieval datasets

    Dynamic trust models for ubiquitous computing environments

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    A significant characteristic of ubiquitous computing is the need for interactions of highly mobile entities to be secure: secure both for the entity and the environment in which the entity operates. Moreover, ubiquitous computing is also characterised by partial views over the state of the global environment, implying that we cannot guarantee that an environment can always verify the properties of the mobile entity that it has just received. Secure in this context encompasses both the need for cryptographic security and the need for trust, on the part of both parties, that the interaction is functioning as expected. In this paper we make a broad assumption that trust and cryptographic security can be considered as orthogonal concerns (i.e. an entity might encrypt a deliberately incorrect answer to a legitimate request). We assume the existence of reliable encryption techniques and focus on the characteristics of a model that supports the management of the trust relationships between two entities during an interaction in a ubiquitous environment

    A tutorial task and tertiary courseware model for collaborative learning communities

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    RAED provides a computerised infrastructure to support the development and administration of Vicarious Learning in collaborative learning communities spread across multiple universities and workplaces. The system is based on the OASIS middleware for Role-based Access Control. This paper describes the origins of the model and the approach to implementation and outlines some of its benefits to collaborative teachers and learners

    Associations between fibrin D-dimer, markers of inflammation, incident self-reported mobility limitation, and all-cause mortality in older men

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    Objectives<p></p> To examine the independent relationships between fibrin D-dimer, interleukin 6 (IL-6), C-reactive protein (CRP), and fibrinogen and incident mobility limitation and mortality.<p></p> Design<p></p> Prospective.<p></p> Setting<p></p> General practice in 24 British towns.<p></p> Participants<p></p> Men aged 60 to 79 without prevalent heart failure followed up for an average of 11.5 years (N = 3,925).<p></p> Measurements<p></p> All-cause mortality (n = 1,286) and self-reported mobility disability obtained at examination in 1998 to 2000 and in a postal questionnaire 3 to 5 years later in 2003.<p></p> Results<p></p> High D-dimer (top vs lowest tertile: adjusted odds ratio (aOR) = 1.46, 95% confidence interval = 1.02–2.05) and IL-6 (aOR = 1.43, 95% CI = 1.01–2.02) levels (but not CRP or fibrinogen) were associated with greater incident mobility limitation after adjustment for confounders and prevalent disease status. IL-6, CRP, fibrinogen, and D-dimer were significantly associated with total mortality after adjustment for confounders. Only D-dimer and IL-6 predicted total mortality independent of each other and the other biomarkers. The adjusted hazard ratio (aHR) was 1.16 (95% CI = 1.10–1.22) for a standard deviation increase in log D-dimer and 1.10 (95% CI = 1.04–1.18) for a standard deviation increase in log IL-6. D-dimer was independently related to vascular and nonvascular mortality, and IL-6 was independently related to vascular mortality. Risks of mobility limitation and mortality were greatest in those with a combination of high D-dimer and IL-6 levels.<p></p> Conclusion<p></p> D-dimer and IL-6 are associated with risk of mobility limitation and mortality in older men without heart failure. The findings suggest that coagulation leads to functional decline and mortality s that inflammation does not explain

    Object Matching in Distributed Video Surveillance Systems by LDA-Based Appearance Descriptors

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    Establishing correspondences among object instances is still challenging in multi-camera surveillance systems, especially when the cameras’ fields of view are non-overlapping. Spatiotemporal constraints can help in solving the correspondence problem but still leave a wide margin of uncertainty. One way to reduce this uncertainty is to use appearance information about the moving objects in the site. In this paper we present the preliminary results of a new method that can capture salient appearance characteristics at each camera node in the network. A Latent Dirichlet Allocation (LDA) model is created and maintained at each node in the camera network. Each object is encoded in terms of the LDA bag-of-words model for appearance. The encoded appearance is then used to establish probable matching across cameras. Preliminary experiments are conducted on a dataset of 20 individuals and comparison against Madden’s I-MCHR is reported

    Probabilistic Search for Object Segmentation and Recognition

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    The problem of searching for a model-based scene interpretation is analyzed within a probabilistic framework. Object models are formulated as generative models for range data of the scene. A new statistical criterion, the truncated object probability, is introduced to infer an optimal sequence of object hypotheses to be evaluated for their match to the data. The truncated probability is partly determined by prior knowledge of the objects and partly learned from data. Some experiments on sequence quality and object segmentation and recognition from stereo data are presented. The article recovers classic concepts from object recognition (grouping, geometric hashing, alignment) from the probabilistic perspective and adds insight into the optimal ordering of object hypotheses for evaluation. Moreover, it introduces point-relation densities, a key component of the truncated probability, as statistical models of local surface shape.Comment: 18 pages, 5 figure

    Using simulated co-heating tests to understand weather driven sources of uncertainty within the co-heating test method

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    The so-called performance gap between designed and as-built building performance threatens to undermine carbon reduction strategies in the built environment. Field measurements to date have indicated that the measured as-built fabric heat loss of tested UK buildings is consistently higher than design values, often considerably so. Currently, our lack of knowledge over the extent of this gap, and the processes that cause it, is compounded by a lack of robust post-construction evaluation tools. Much of this post-construction evaluation work is based, in part, on the use of co-heating tests: a method utilising an energy balance to determine the heat loss across the entire building envelope, defined by the heat loss coefficient (W/K). However, the errors associated with co-heating are not well understood or typically addressed in the literature. Furthermore, the test procedure requires a building to be unoccupied for two to three weeks and is therefore often cited as costly and unsuitable both for developers and as a policy tool. In order to improve the application of this test method it is crucial firstly to understand the sources of uncertainty in co-heating tests and the ‘steady-state’ energy balance they are based upon. However, with a small database of tests performed to date it is difficult to discern these sources of error. This paper presents the results of a method using simulated co-heating tests to show how key weather variables influence the co-heating result and generate uncertainty and bias. In particular the effects of short-wave solar and long-wave sky radiation are presented. Improvements to the co-heating method can be derived from this; in particular the need to consider when dwellings should be tested to avoid large solar-generated errors and the importance of a accurately calculated solar aperture. Recommendations also include the local measurement of sky radiation to avoid outlying data points, bias in the measurement and discrepancies when comparing design and as-built heat loss

    A study of blood contamination of Siqveland matrix bands

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    AIMS To use a sensitive forensic test to measure blood contamination of used Siqveland matrix bands following routine cleaning and sterilisation procedures in general dental practice. MATERIALS AND METHODS: Sixteen general dental practices in the West of Scotland participated. Details of instrument cleaning procedures were recorded for each practice. A total of 133 Siqveland matrix bands were recovered following cleaning and sterilisation and were examined for residual blood contamination by the Kastle-Meyer test, a well-recognised forensic technique. RESULTS: Ultrasonic baths were used for the cleaning of 62 (47%) bands and retainers and the remainder (53%) were hand scrubbed prior to autoclaving. Overall, 21% of the matrix bands and 19% of the retainers gave a positive Kastle-Meyer test, indicative of residual blood contamination, following cleaning and sterilisation. In relation to cleaning method, 34% of hand-scrubbed bands and 32% of hand-scrubbed retainers were positive for residual blood by the Kastle-Meyer test compared with 6% and 3% respectively of ultrasonically cleaned bands and retainers (P less than 0.001). CONCLUSIONS: If Siqveland matrix bands are re-processed in the assembled state, then adequate pre-sterilisation cleaning cannot be achieved reliably. Ultrasonic baths are significantly more effective than hand cleaning for these items of equipment

    Instrumentation for hydrogen slush storage containers

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    Hydrogen liquid and slush tank continuous inventory during ground storag

    Comments on the black hole information problem

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    String theory provides numerous examples of duality between gravitational theories and unitary gauge theories. To resolve the black hole information paradox in this setting, it is necessary to better understand how unitarity is implemented on the gravity side. We argue that unitarity is restored by nonlocal effects whose initial magnitude is suppressed by the exponential of the Bekenstein-Hawking entropy. Time-slicings for which effective field theory is valid are obtained by demanding the mutual back-reaction of quanta be small. The resulting bounds imply that nonlocal effects do not lead to observable violations of causality or conflict with the equivalence principle for infalling observers, yet implement information retrieval for observers who stay outside the black hole.Comment: 18 pages, 2 figures, revtex, v2 figure added and some improvements to presentatio
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