162,907 research outputs found

    Testing goodwill: Conflict and co-operation in new product development networks

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    Network forms are often seen as models of organisational flexibility, promoting the building of trust and exchange of information between different business functions while offering both cost savings and reductions in the uncertainties usually associated with innovation. Both internal and external networks have been identified as key elements in the collaborative development of new products. The actual process of network building and ongoing network management is not well researched, although the existing literature highlights difficulties for organisations attempting to maintain active product development networks. This article examines the development and management of such a network in the defence industry and focuses on network building processes in terms of the interactions between the individuals involved. This network has endured and evolved over many years despite a series of conflicts. One of the key findings is that the effective functioning of the overall network is closely allied to established processes within the two participating firms

    Impaired carotid viscoelastic properties in women with polycystic ovaries

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    Background-The purpose of this study was to assess the elastic properties of the carotid arteries in women with polycystic ovarian syndrome, asymptomatic women with polycystic ovaries. and healthy controls.Methods and Results-We recruited the following 60 subjects: 20 symptomatic women with polycystic ovaries attending the reproductive endocrinology clinics, 20 asymptomatic women with polycystic ovaries attending the family planning clinic, and 20 staff volunteers as healthy controls with normal ovaries on transvaginal scan. Compliance and stiffness index were assessed in the common and internal carotid arteries using duplex ultrasound equipped with an echo-locked arterial wall-tracking system. Compliance was significantly lower in the common carotid artery in symptomatic and asymptomatic women with polycystic ovaries than in the controls (10.7, 14.1, and 19.2%mm Hg-1 x 10(-2), respectively). The arterial stiffness index was correspondingly increased (12.3, 10.2, and 6.7, respectively). Similar results were obtained in the internal carotid artery for compliance (10.1. 11.0, and 16.9 %mm Hg-1 x 10(-2), respectively) and stiffness index (14.8, 16.2, and 8.7, respectively).Conclusions-The results of this study provide additional evidence of vascular dysfunction in women with polycystic ovaries and are compatible with the hypothesis that they are at increased risk from coronary artery disease and stroke

    Preliminary analysis of fuel tank impact

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    Following the accident involving the Air France Concorde in 2000 the effects of fluid structure interactions resulting from the impact of a fluid filled tank has become a cause for concern. The work reported here relates to the design of a series of experiments loosely based upon the Concorde incident which aimed to assess whether the probable failure mode in the Concorde accident could occur in land based vessels. Preliminary numerical analyses were undertaken for two of the nine cases that were investigated experimentally in which an empty tank was impacted by a projectile with a velocity of 14m/s and 21.9m/s Initial numerical results for the acceleration at two points on the tank surface and the deformation at the impact zone showed good agreement with test data. Future work is discussed including further numerical modelling incorporating fluid structure interactions for the analysis of the cases when the tank is partially full or completely full

    Colouration in crab spiders: substrate choice and prey attraction

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    Published version: http://jeb.biologists.org/content/208/10/1785/F3.expansio

    Probabilistic abductive logic programming using Dirichlet priors

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    Probabilistic programming is an area of research that aims to develop general inference algorithms for probabilistic models expressed as probabilistic programs whose execution corresponds to inferring the parameters of those models. In this paper, we introduce a probabilistic programming language (PPL) based on abductive logic programming for performing inference in probabilistic models involving categorical distributions with Dirichlet priors. We encode these models as abductive logic programs enriched with probabilistic definitions and queries, and show how to execute and compile them to boolean formulas. Using the latter, we perform generalized inference using one of two proposed Markov Chain Monte Carlo (MCMC) sampling algorithms: an adaptation of uncollapsed Gibbs sampling from related work and a novel collapsed Gibbs sampling (CGS). We show that CGS converges faster than the uncollapsed version on a latent Dirichlet allocation (LDA) task using synthetic data. On similar data, we compare our PPL with LDA-specific algorithms and other PPLs. We find that all methods, except one, perform similarly and that the more expressive the PPL, the slower it is. We illustrate applications of our PPL on real data in two variants of LDA models (Seed and Cluster LDA), and in the repeated insertion model (RIM). In the latter, our PPL yields similar conclusions to inference with EM for Mallows models

    On the mechanism of trailing vortex wandering

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    The mechanism of trailing vortex wandering has long been debated and is often attributed to either wind-tunnel effects or an instability. Using particle image velocimetry data obtained in the wake of a NACA0012 airfoil, we remove the effect of wandering from the measured velocity field and, through a triple decomposition, recover the coherent wandering motion. Based on this wandering motion, the most energetic structures are computed using the proper orthogonal decomposition (POD) and exhibit a helical mode with an azimuthal wavenumber of |m|=1 whose kinetic energy grows monotonically in the downstream direction. To investigate the nature of the vortex wandering, we perform a spatial stability analysis of a matched Batchelor vortex. The primary stability mode is found to be marginally stable and nearly identical in both size and structure to the leading POD mode. The strikingly similar structure, coupled with the measured energy growth, supports the proposition that the vortex wandering is the result of an instability. We conclude that the cause of the wandering is the non-zero radial velocity of the |m|=1 mode on the vortex centreline, which acts to transversely displace the trailing vortex, as observed in experiments. However, the marginal nature of the stability mode prevents a definitive conclusion regarding the specific type of instability

    Learning about sex: Results from Natsal 2000.

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    11-13 September 2002
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