Phantom cascades: The effect of hidden nodes on information diffusion

Research on information diffusion generally assumes complete knowledge of the underlying network. However, in the presence of factors such as increasing privacy awareness, restrictions on application programming interfaces (APIs) and sampling strategies, this assumption rarely holds in the real world which in turn leads to an underestimation of the size of information cascades. In this work we study the effect of hidden network structure on information diffusion processes. We characterise information cascades through activation paths traversing visible and hidden parts of the network. We quantify diffusion estimation error while varying the amount of hidden structure in five empirical and synthetic network datasets and demonstrate the effect of topological properties on this error. Finally, we suggest practical recommendations for practitioners and propose a model to predict the cascade size with minimal information regarding the underlying network.Comment: Preprint submitted to Elsevier Computer Communication

Consumer Footprint. Basket of Products indicator on Food

The EU Consumer Footprint aims at assessing the potential environmental impacts due to consumption. The calculation of the Consumer footprint is based on the life cycle assessment (LCA) of representative products (or services) purchased and used in one year by an EU citizen. This report is about the subset indicator of the basket of product (BoP) on food. The BoP food is built to assess the impact associated to food consumption in Europe from raw material extraction to end of life. The reference flow is the amount of food consumed by an average citizen in a reference year. It consists of a process-based life cycle inventory model for a basket of products that represent the most relevant food product groups, selected by importance in mass and economic value. The 19 products in the basket are: pork, beef and poultry meat, milk, cheese, butter, bread, sugar, sunflower oil, olive oil, potatoes, oranges, apples, mineral water, roasted coffee, beer, pre-prepared meals, wine, and pasta. The consumer footprint for the BoP food is assessed using 15 environmental impact categories as for the ILCD LCIA method and running a sensitivity for a number of impact categories with updated models. Results show that agriculture is the life cycle stage of the food system with the larger contribution to most of the impact categories. The product groups that emerge as hotspots in most of the impact categories are meat products, dairy products, and beverages. The main impact for the life cycle of meat products comes from the emissions due to agricultural activities for the production of feed. Direct emissions from animal husbandry (methane, dinitrogen oxide, ammonia, etc.) contribute as well. Normalized results show that the BoP food contributes significantly to several impact categories, with a different ranking depending upon the adopted normalisation reference (European or global). Ecotoxicity, human toxicity, eutrophication, acidification, water depletion and climate change are among the leading impacts. Since many LCA study on food are limited to the assessment of climate change related emissions, the BoP food baseline aims at helping to understand the wider array of impacts associated to the food system of production and consumption. Moreover, the Consumer Footprint BoP food baseline has been assessed against 5 scenarios, referring to improvement options related to the main drivers of impact. In fact, the scenarios act on the hotspots identified within the baseline and refer to the most relevant eco-innovations and behavioural changes identified through a review of the scientific literature. Scenario 1 and Scenario 4 act on the nutrients cycle, with the aim of recovering nutrients either at the production stage or the end of life stage. Scenario 2 acts at the end of life stage as well, by assuming an improvement of the efficiency of the waste water treatment in Europe. Scenario 3 is a first attempt to address the benefits of behavioural changes, with an example of reduced amount of meat consumed. Scenario 5 regards the topic of food waste prevention, and entails a number of prevention measures, acting at different stages of the food supply chain, including the use phase. The scenarios tested on the baseline of the BoP food provided insights on the potential for reducing environmental impacts of food consumption in Europe. Each scenario acts on a different component of the BoP (in term of either products, life cycle stages or composition of the basket). As the scenarios are different in type it was found out that the was a large difference on the different scores and savings among the investigated impact categories. In general, among the scenarios assessed, the options that allow for a higher reduction of impacts are the ones acting on the drivers of freshwater eutrophication, such as recovery of nutrients from urine or improvement of the wastewater treatment. It is important to highlight that results of scenarios shall be analysed considering a certain “uptake factor” across EU (it is not realistic to assume 100% change across EU27). It is also recommended to consider the combination of improvement actions, to cover a wider range of impacts and to maximize the potential of impact reduction, both at the scale of the single citizen and of the whole Europe. An example has been provided in the case of combined actions for the scenario on food waste prevention.JRC.D.1-Bio-econom

Any-k: Anytime Top-k Tree Pattern Retrieval in Labeled Graphs

Many problems in areas as diverse as recommendation systems, social network analysis, semantic search, and distributed root cause analysis can be modeled as pattern search on labeled graphs (also called "heterogeneous information networks" or HINs). Given a large graph and a query pattern with node and edge label constraints, a fundamental challenge is to nd the top-k matches ac- cording to a ranking function over edge and node weights. For users, it is di cult to select value k . We therefore propose the novel notion of an any-k ranking algorithm: for a given time budget, re- turn as many of the top-ranked results as possible. Then, given additional time, produce the next lower-ranked results quickly as well. It can be stopped anytime, but may have to continues until all results are returned. This paper focuses on acyclic patterns over arbitrary labeled graphs. We are interested in practical algorithms that effectively exploit (1) properties of heterogeneous networks, in particular selective constraints on labels, and (2) that the users often explore only a fraction of the top-ranked results. Our solution, KARPET, carefully integrates aggressive pruning that leverages the acyclic nature of the query, and incremental guided search. It enables us to prove strong non-trivial time and space guarantees, which is generally considered very hard for this type of graph search problem. Through experimental studies we show that KARPET achieves running times in the order of milliseconds for tree patterns on large networks with millions of nodes and edges.Comment: To appear in WWW 201

Compressive Sensing for Dynamic XRF Scanning

X-Ray Fluorescence (XRF) scanning is a widespread technique of high importance and impact since it provides chemical composition maps crucial for several scientific investigations. There are continuous requirements for larger, faster and highly resolved acquisitions in order to study complex structures. Among the scientific applications that benefit from it, some of them, such as wide scale brain imaging, are prohibitively difficult due to time constraints. However, typically the overall XRF imaging performance is improving through technological progress on XRF detectors and X-ray sources. This paper suggests an additional approach where XRF scanning is performed in a sparse way by skipping specific points or by varying dynamically acquisition time or other scan settings in a conditional manner. This paves the way for Compressive Sensing in XRF scans where data are acquired in a reduced manner allowing for challenging experiments, currently not feasible with the traditional scanning strategies. A series of different compressive sensing strategies for dynamic scans are presented here. A proof of principle experiment was performed at the TwinMic beamline of Elettra synchrotron. The outcome demonstrates the potential of Compressive Sensing for dynamic scans, suggesting its use in challenging scientific experiments while proposing a technical solution for beamline acquisition software.Comment: 16 pages, 7 figures, 1 tabl

An Experimental Study on Young Pupils

Chess is thought to be a game demanding high cognitive abilities to be played well. Although many studies proved the link between mastery in chess and high degree of intelligence, just few studies proved that chess practice can enhance cognitive abilities. Starting from these considerations, the main purpose of the present research was to investigate the potential benefits of in-presence chess lessons and on-line training on mathematical problem-solving ability in young pupils (8 to 11 years old). Five hundred sixty students were divided into two groups, experimental (which had chess course and on-line training) and control (which had normal school activities), and tested on their mathematical and chess abilities. Results show a strong correlation between chess and math scores, and a higher improvement in math in the experimental group compared with the control group. These results foster the hypothesis that even a short-time practice of chess in children can be a useful tool to enhance their mathematical abilities

Wunderkammern and dissemination for children: Knowing and imagining through wonder

Wunderkammern represent a truly interesting phenomenon not only because of their pe- culiar feature of collecting amazing, even monstrous, items from all over the planet, but especially for the importance given to feelings such as curiosity, wonder and astonish- ment in the process of discovering the world, as a medium to get to knowledge. Wunder- kammern, also known as Cabinets of Curiosities, keep being represented in art and enter- tainment, with particular relevance to their most grotesque aspects; here, the focus is on two depictions coming from non-fiction children’s literature, which has gone through a recent wave of innovation regarding specifically the picturebooks form. The non-fiction picturebooks edited in the last decade appear to have in common a significant illustration and design apparatus, resulting in a strongly creative and aesthetic approach to knowledge: engaging the senses – and therefore inspiring awe and wonder – together with data and information, these non-fiction picturebooks contribute to restore value to art and beauty in the learning process, revealing a sort of relationship with the Wunderkammer paradigm.Wunderkammern represent a truly interesting phenomenon not only because of their peculiar feature of collecting amazing, even monstrous, items from all over the planet, but especially for the importance given to feelings such as curiosity, wonder and astonishment in the process of discovering the world, as a medium to get to knowledge.Wunderkammern, also known as Cabinets of Curiosities, keep being represented in art and entertainment, with particular relevance to their most grotesque aspects; here, the focus is on two depictions coming from non-fiction children’s literature, which has gone through a recent wave of innovation regarding specifically the picturebooks form. The non-fiction picturebooks edited in the last decade appear to have in common a significant illustration and design apparatus, resulting in a strongly creative and aesthetic approach to knowledge: engaging the senses – and therefore inspiring awe and wonder – together with data and information, these non-fiction picturebooks contribute to restore value to art and beauty in the learning process, revealing a sort of relationship with the Wunderkammer paradigm

The Stat3-Fam3a axis promotes muscle stem cell myogenic lineage progression by inducing mitochondrial respiration.

Metabolic reprogramming is an active regulator of stem cell fate choices, and successful stem cell differentiation in different compartments requires the induction of oxidative phosphorylation. However, the mechanisms that promote mitochondrial respiration during stem cell differentiation are poorly understood. Here we demonstrate that Stat3 promotes muscle stem cell myogenic lineage progression by stimulating mitochondrial respiration in mice. We identify Fam3a, a cytokine-like protein, as a major Stat3 downstream effector in muscle stem cells. We demonstrate that Fam3a is required for muscle stem cell commitment and skeletal muscle development. We show that myogenic cells secrete Fam3a, and exposure of Stat3-ablated muscle stem cells to recombinant Fam3a in vitro and in vivo rescues their defects in mitochondrial respiration and myogenic commitment. Together, these findings indicate that Fam3a is a Stat3-regulated secreted factor that promotes muscle stem cell oxidative metabolism and differentiation, and suggests that Fam3a is a potential tool to modulate cell fate choices