445 research outputs found

    Consensus Message Passing for Layered Graphical Models

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    Generative models provide a powerful framework for probabilistic reasoning. However, in many domains their use has been hampered by the practical difficulties of inference. This is particularly the case in computer vision, where models of the imaging process tend to be large, loopy and layered. For this reason bottom-up conditional models have traditionally dominated in such domains. We find that widely-used, general-purpose message passing inference algorithms such as Expectation Propagation (EP) and Variational Message Passing (VMP) fail on the simplest of vision models. With these models in mind, we introduce a modification to message passing that learns to exploit their layered structure by passing 'consensus' messages that guide inference towards good solutions. Experiments on a variety of problems show that the proposed technique leads to significantly more accurate inference results, not only when compared to standard EP and VMP, but also when compared to competitive bottom-up conditional models.Comment: Appearing in Proceedings of the 18th International Conference on Artificial Intelligence and Statistics (AISTATS) 201

    The Effect of Bacterial Endotoxin Upon the Morphology of the Tectorial Membrane and Stereocilia in the Guinea Pig Cochlea

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    Endotoxin of E coli was microperfused into scala tympani or injected into the cerebrospinal fluid in anaesthetised pigmented guinea pigs. The effects of endotoxin on the cochlea were studied using electrophysiological techniques and scanning electron microscopy. We found a drop in the amplitude of the cochlear microphonics and compound action potentials 2 to 2.5 hours after injection. There were also changes in the morphology of stereocilia and the tectorial membrane. The stereocilia lost their rigidity and the tectorial membrane appeared swollen. These effects were less severe in animals which were pretreated with dexamethasone

    Bipotential Adult Liver Progenitors Are Derived from Chronically Injured Mature Hepatocytes

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    SummaryAdult liver progenitor cells are biliary-like epithelial cells that emerge only under injury conditions in the periportal region of the liver. They exhibit phenotypes of both hepatocytes and bile ducts. However, their origin and their significance to injury repair remain unclear. Here, we used a chimeric lineage tracing system to demonstrate that hepatocytes contribute to the progenitor pool. RNA-sequencing, ultrastructural analysis, and in vitro progenitor assays revealed that hepatocyte-derived progenitors were distinct from their biliary-derived counterparts. In vivo lineage tracing and serial transplantation assays showed that hepatocyte-derived proliferative ducts retained a memory of their origin and differentiated back into hepatocytes upon cessation of injury. Similarly, human hepatocytes in chimeric mice also gave rise to biliary progenitors in vivo. We conclude that human and mouse hepatocytes can undergo reversible ductal metaplasia in response to injury, expand as ducts, and subsequently contribute to restoration of the hepatocyte mass

    Popular attitudes to memory, the body, and social identity : the rise of external commemoration in Britain, Ireland, and New England

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    A comparative analysis of samples of external memorials from burial grounds in Britain, Ireland and New England reveals a widespread pattern of change in monument style and content, and exponential growth in the number of permanent memorials from the 18th century onwards. Although manifested in regionally distinctive styles on which most academic attention has so far been directed, the expansion reflects global changes in social relationships and concepts of memory and the body. An archaeological perspective reveals the importance of external memorials in articulating these changing attitudes in a world of increasing material consumption

    Challenging the negative images of Haiti at a pre-visit stage using visual online learning materials

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    Post-conflict destinations can struggle to attract visitors because of their negative image. Research addressing this remains limited. The same can be said about the education of tourists. This research paper contributes to the literature in both areas as it examines the proposition that the education of tourists at a pre-visit stage using online, game-based material could be effective in challenging the negative perception of these destinations. From a destination management point of view, this paper offers an alternative to existing promotional material as there is little evidence at the moment that existing strategies are effective. From a conceptual point of view, this paper contributes to the very limited academic research in Gamification by adding the fact that Gamification can be a very efficient tryvertising tool if using subtle and implicit marketing elements

    Positive and negative evaluation of caregiving among three different types of informal care relationships

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    Based on the caregiver stress model, we examined how care demands, caregiver motivation, coping style and external support are associated with positive evaluation and caregiver burden among spousal, adult child and other types of care relations. Data from a sample of Dutch informal caregivers of 1,685 older persons (55 and older) were analyzed employing multivariate linear regression analyses for each of the care relationship types. Spouses (N = 206) report high positive evaluation and high burden, adult children (N = 1,093) report low positive evaluation, and other caregivers (N = 386) report high positive evaluation and a low burden. Multivariate linear regression analyses showed that motives and external support were important for positive evaluation but the impact varied among types of caregivers, whereas care demands and not asking for help were associated with burden for all types. Only among 'other' caregiver relationships, positive evaluation was negatively associated with burden. It is concluded that results confirm the dual nature of caregiving among spouses and children. The care context and motivation of the different types of caregivers explain their differences in care evaluation. Various interventions for types of caregivers are discussed. © 2013 Springer-Verlag Berlin Heidelberg

    "Invisible burials" and fragmentation practices in Iron Age Europe:Excavations at the Monte Bernorio Necropolis (Northern Spain)

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    The scarcity of burial remains in large parts of Iron Age Europe, particularly in the Atlantic regions, has often led scholars to discuss the apparent “invisibility” of graves. This paper presents the results from several excavation campaigns at Monte Bernorio, one of the most important sites of the 1st millennium b.c. on the Iberian Peninsula. The fieldwork and post-excavation work carried out in the area of the necropolis have identified numerous burial pits, with complex ritual activities characterized by fragmentation and the practice of the pars pro toto. In addition, evidence for later rituals in some of the graves can be linked to ancestor worship. The results provide important insights into funerary practices in Late Iron Age Europe, leading us to rethink the very meaning of cemeteries in the study area and beyond.- Burial Traditions in Iron Age Europe - The Monte Bernorio Archaeological Zone - The 2007–2008 Necropolis Excavations - The 2015–2016 Necropolis Excavations - Post-Excavation Work and Interpretation: The Faunal and Human Remains - Structure and Chronology of Monte Bernorio Area 7 - Destruction of the Body, Commemoration in the Absence of a Corpse, and Visibility of the Mortuary Rite

    Elevated white cell count in acute coronary syndromes: relationship to variants in inflammatory and thrombotic genes

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    BACKGROUND: Elevated white blood cell counts (WBC) in acute coronary syndromes (ACS) increase the risk of recurrent events, but it is not known if this is exacerbated by pro-inflammatory factors. We sought to identify whether pro-inflammatory genetic variants contributed to alterations in WBC and C-reactive protein (CRP) in an ACS population. METHODS: WBC and genotype of interleukin 6 (IL-6 G-174C) and of interleukin-1 receptor antagonist (IL1RN intronic repeat polymorphism) were investigated in 732 Caucasian patients with ACS in the OPUS-TIMI-16 trial. Samples for measurement of WBC and inflammatory factors were taken at baseline, i.e. Within 72 hours of an acute myocardial infarction or an unstable angina event. RESULTS: An increased white blood cell count (WBC) was associated with an increased C-reactive protein (r = 0.23, p < 0.001) and there was also a positive correlation between levels of β-fibrinogen and C-reactive protein (r = 0.42, p < 0.0001). IL1RN and IL6 genotypes had no significant impact upon WBC. The difference in median WBC between the two homozygote IL6 genotypes was 0.21/mm(3 )(95% CI = -0.41, 0.77), and -0.03/mm(3 )(95% CI = -0.55, 0.86) for IL1RN. Moreover, the composite endpoint was not significantly affected by an interaction between WBC and the IL1 (p = 0.61) or IL6 (p = 0.48) genotype. CONCLUSIONS: Cytokine pro-inflammatory genetic variants do not influence the increased inflammatory profile of ACS patients

    Stressful conditions reveal decrease in size, modification of shape but relatively stable asymmetry in bumblebee wings

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    Human activities can generate a wide variety of direct and indirect effects on animals, which can manifest as environmental and genetic stressors. Several phenotypic markers have been proposed as indicators of these stressful conditions but have displayed contrasting results, depending, among others, on the phenotypic trait measured. Knowing the worldwide decline of multiple bumblebee species, it is important to understand these stressors and link them with the drivers of decline. We assessed the impact of several stressors (i.e. natural toxin-, parasite-, thermic- and inbreeding-stress) on both wing shape and size and their variability as well as their directional and fluctuating asymmetries. The total data set includes 650 individuals of Bombus terrestris (Hymenoptera: Apidae). Overall wing size and shape were affected by all the tested stressors. Except for the sinigrin (e.g. glucosinolate) stress, each stress implies a decrease of wing size. Size variance was affected by several stressors, contrary to shape variance that was affected by none of them. Although wing size directional and fluctuating asymmetries were significantly affected by sinigrin, parasites and high temperatures, neither directional nor fluctuating shape asymmetry was significantly affected by any tested stressor. Parasites and high temperatures led to the strongest phenotype modifications. Overall size and shape were the most sensitive morphological traits, which contrasts with the common view that fluctuating asymmetry is the major phenotypic marker of stress
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