407 research outputs found
Front Matter, Table of Contents, Preface, List of Authors
No full textFront Matter, Table of Contents, Preface, List of Author
Asset price bubbles and monetary policy: Revisiting the nexus at the zero lower bound
No full textAsset price bubbles are a major source of macroeconomic instability, but can they play a different role in a low interest rates environment? To answer this question, I study an econ-omy in which the natural rate of interest declines permanently, and the zero lower bound makes risk-free interest rates persistently low. Asset price bubbles redistribute wealth across generations because of the life-cycle pattern of net worth. In this way, they increase the natural interest rate by serving as a store of value for older cohorts and as a collateral for the younger ones, and the central bank can escape from the ZLB with potential output and welfare gains. Output gains are further amplified in presence of capital accumulation and the "financial accelerator". However, not all bubble types increase the natural interest rate to the same degree and, in this respect, leveraged bubbles have a greater impact than unleveraged bubbles.(c) 2022 Elsevier Inc. All rights reserved
The dual personality of iron chelators: growth inhibitors or promoters?
No full text[No abstract available
Pyochelin potentiates the inhibitory activity of gallium on Pseudomonas aeruginosa.
No full textGallium (Ga) is an iron mimetic that has successfully been repurposed for antibacterial chemotherapy. To improve the antibacterial potency of Ga on Pseudomonas aeruginosa, the effect of complexation with a variety of siderophores and synthetic chelators was tested. Ga complexed with the pyochelin siderophore (at a 1:2 ratio) was more efficient than Ga(NO3)3 in inhibiting P. aeruginosa growth, and its activity was dependent on increased Ga entrance into the cell through the pyochelin translocon
Voting in social networks
No full textA voting system is a set of rules that a community adopts to take collective decisions. In this paper we study voting systems for a particular kind of community: electronically mediated social networks. In particular, we focus on delegative democracy (a.k.a. proxy voting) that has recently received increased interest for its ability to combine the benefits of direct and representative systems, and that seems also perfectly suited for electronically mediated social networks. In such a context, we consider a voting system in which users can only express their preference for one among the people they are explicitly connected with, and this preference can be propagated transitively, using an attenuation factor.
We present this system and we study its properties. We also take into consideration the problem of missing votes, which is particularly relevant in online networks, as some recent case shows. Our experiments on real-world networks provide interesting insight into the significance and stability of the results obtained with the suggested voting system
Query reformulation mining: models, patterns, and applications
No full textUnderstanding query reformulation patterns is a key task towards next generation web search engines. If we can do that, then we can build systems able to understand and possibly predict user intent, providing the needed assistance at the right time, and thus helping users locate information more effectively and improving their web-search experience. As a step in this direction, we build a very accurate model for classifying user query reformulations into broad classes (generalization, specialization, error correction or parallel move), achieving 92% accuracy. We then apply the model to automatically label two very large query logs sampled from different geographic areas, and containing a total of approximately 17 million query reformulations. We study the resulting reformulation patterns, matching some results from previous studies performed on smaller manually annotated datasets, and discovering new interesting reformulation patterns, including connections between reformulation types and topical categories. We annotate two large query-flow graphs with reformulation type information, and run several graph-characterization experiments on these graphs, extracting new insights about the relationships between the different query reformulation types. Finally we study query recommendations based on short random walks on the query-flow graphs. Our experiments show that these methods can match in precision, and often improve, recommendations based on query-click graphs, without the need of users’ clicks. Our experiments also show that it is important to consider transition-type labels on edges for having recommendations of good quality
Viscous democracy for social networks
No full textDecision-making procedures in online social networks should reflect participants' political influence within the network
Promises and failures of gallium as an antibacterial agent
No full textGallium has a long history as diagnostic and chemotherapeutic agent. The pharmacological properties of Ga(III) rely on chemical mimicry; when Ga(III) is exogenously supplied to living cells it can replace Fe(III) within target molecules, thereby perturbing bacterial metabolism. Ga(III)-induced metabolic distresses are dramatic in fast-growing cells, like bacterial cells. Interest in the antibacterial properties of Ga(III) has been raised by the compelling need for novel drugs to combat multidrug-resistant bacteria and by the shortage of new antibiotic candidates in the pharmaceutical pipeline. Ga(III) activity has been demonstrated, both in vitro and in animal models of infections, on several bacterial pathogens, also including intracellular and biofilm-forming bacteria. Ga(III) activity is affected by iron availability and the metabolic state of the cell, being maximal in iron-poor media and on respiring cells. Synergism between Ga(III) and antibiotics holds promise as last resort therapy of infections sustained by pandrug-resistant bacteria
Mining (maximal) Span-cores from Temporal Networks
No full textWhen analyzing temporal networks, a fundamental task is the identification of dense structures (i.e., groups of vertices that exhibit a large number of links), together with their temporal span (i.e., the period of time for which the high density holds). We tackle this task by introducing a notion of temporal core decomposition where each core is associated with its span: we call such cores span-cores. As the total number of time intervals is quadratic in the size of the temporal domain T under analysis, the total number of span-cores is quadratic in |T | as well. Our first contribution is an algorithm that, by exploiting containment properties among span-cores, computes all the span-cores efficiently. Then, we focus on the problem of finding only the maximal span-cores, i.e., span-cores that are not dominated by any other span-core by both the coreness property and the span. We devise a very efficient algorithm that exploits theoretical findings on the maximality condition to directly compute the maximal ones without computing all span-cores. Experimentation on several real-world temporal networks confirms the efficiency and scalability of our methods. Applications on temporal networks, gathered by a proximity-sensing infrastructure recording face-to-face interactions in schools, highlight the relevance of the notion of (maximal) span-core in analyzing social dynamics and detecting/correcting anomalies in the data
Effect of siderophores and iron chelators on gallium inhibitory activity in Pseudomonas aeruginosa
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