13,187 research outputs found

    Structure Selection from Streaming Relational Data

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    Statistical relational learning techniques have been successfully applied in a wide range of relational domains. In most of these applications, the human designers capitalized on their background knowledge by following a trial-and-error trajectory, where relational features are manually defined by a human engineer, parameters are learned for those features on the training data, the resulting model is validated, and the cycle repeats as the engineer adjusts the set of features. This paper seeks to streamline application development in large relational domains by introducing a light-weight approach that efficiently evaluates relational features on pieces of the relational graph that are streamed to it one at a time. We evaluate our approach on two social media tasks and demonstrate that it leads to more accurate models that are learned faster

    Expectation thinning operators based on linear fractional probability generating functions

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    We introduce a two-parameter expectation thinning operator based on a linear fractional probability generating function. The operator is then used to define a first-order integer-valued autoregressive \inar1 process. Distributional properties of the \inar1 process are described. We revisit the Bernoulli-geometric \inar1 process of Bourguignon and Wei{\ss} (2017) and we introduce a new stationary \inar1 process with a compound negative binomial distribution. Lastly, we show how a proper randomization of our operator leads to a generalized notion of monotonicity for distributions on \bzp

    Improving Building Fabric Energy Efficiency in Hot-Humid Climates using Dynamic Insulation

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    Portal vein thrombosis and arterioportal shunts : effects on tumor response after chemoembolization of hepatocellular carcinoma

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    AIM: To evaluate the effect of portal vein thrombosis and arterioportal shunts on local tumor response in advanced cases of unresectable hepatocellular carcinoma treated by transarterial chemoembolization. METHODS: A retrospective study included 39 patients (mean age: 66.4 years, range: 45-79 years, SD: 7) with unresectable hepatocellular carcinoma (HCC) who were treated with repetitive transarterial chemoembolization (TACE) in the period between March 2006 and October 2009. The effect of portal vein thrombosis (PVT) (in 19 out of 39 patients), the presence of arterioportal shunt (APS) (in 7 out of 39), the underlying liver pathology, Child-Pugh score, initial tumor volume, number of tumors and tumor margin definition on imaging were correlated with the local tumor response after TACE. The initial and end therapy local tumor responses were evaluated according to the response evaluation criteria in solid tumors (RECIST) and magnetic resonance imaging volumetric measurements. RESULTS: The treatment protocols were well tolerated by all patients with no major complications. Local tumor response for all patients according to RECIST criteria were partial response in one patient (2.6%), stable disease in 34 patients (87.1%), and progressive disease in 4 patients (10.2%). The MR volumetric measurements showed that the PVT, APS, underlying liver pathology and tumor margin definition were statistically significant prognostic factors for the local tumor response (P = 0.018, P = 0.008, P = 0.034 and P = 0.001, respectively). The overall 6-, 12- and 18-mo survival rates from the initial TACE were 79.5%, 37.5% and 21%, respectively. CONCLUSION: TACE may be exploited safely for palliative tumor control in patients with advanced unresectable HCC; however, tumor response is significantly affected by the presence or absence of PVT and APS

    The Implications of World Trade Liberalization on Agricultural Trade and Food Security: A Case Study of Sudan

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    This paper assesses and quantifies the consequences of world trade liberalization in agriculture on trade and food security of Sudan. Sudan, with the agricultural sector as the main sector of economy, is characterized by its small open economy, and is classified as one of the least developed countries. Thus, Sudan becomes more vulnerable to any changes in international agricultural markets. The liberalization of international agricultural trade has a great influence on Sudan's food security and on the whole economy. An extended form of a multi-market model for Sudan is developed and used for the analysis. The model embodies important characteristics of agriculture in Sudan like substitution effects and stages of production. As agriculture is the main sector of Sudan's economy, the model is extended to explicitly integrate some of the key important macroeconomic linkages, and to establish certain feedback effects between agriculture and the macro-economy. The model simulations reveal that a higher world market price would overall lead to measurable gains in food security and agricultural trade of the country. However, when the effect of a higher cost of production is considered, the positive results are reversed. Furthermore, the results of the model simulations show that the domestic policy environment matters very much with respect to the potential impact of world trade liberalization of agriculture. The paper concludes that Sudan should reorient its national policies towards export promotion in order to benefit from the new emerging trading opportunities in world markets. However, to capture a greater benefit from the new environment in the international markets, Sudan should consider and manage carefully all factors, domestically or internationally - e.g. quality standard, loss of preference, dumping effects - that hinder its economic and trade growth.International Relations/Trade,

    Le risque en agriculture

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