Shadowing and shielding: Effective heuristics for continuous influence maximisation in the voting dynamics

Influence maximisation, or how to affect the intrinsic opinion dynamics of a social group, is relevant for many applications, such as information campaigns, political competition, or marketing. Previous literature on influence maximisation has mostly explored discrete allocations of influence, i.e. optimally choosing a finite fixed number of nodes to target. Here, we study the generalised problem of continuous influence maximisation where nodes can be targeted with flexible intensity. We focus on optimal influence allocations against a passive opponent and compare the structure of the solutions in the continuous and discrete regimes. We find that, whereas hub allocations play a central role in explaining optimal allocations in the discrete regime, their explanatory power is strongly reduced in the continuous regime. Instead, we find that optimal continuous strategies are very well described by two other patterns: (i) targeting the same nodes as the opponent (shadowing) and (ii) targeting direct neighbours of the opponent (shielding). Finally, we investigate the game-theoretic scenario of two active opponents and show that the unique pure Nash equilibrium is to target all nodes equally. These results expose fundamental differences in the solutions to discrete and continuous regimes and provide novel effective heuristics for continuous influence maximisation.

Analysis of some economic-financial ratios to analyse the financial crisis in five-star hotels in Barcelona and Madrid

Purpose: Analyse some of the financial ratios to see the impact of the economic crisis on 5-star hotels in Spain.Design/methodology/approach: The information needed to write this article was taken from the Iberian Balance Sheet Analysis System (SABI), the Hotel Occupancy Survey published periodically by the National Statistics Institute, the IDESCAT and the official websites of the hotels analysed.Findings and Originality/value: The results obtained show how the financial crisis did not have a direct impact on luxury hotels, but on the contrary, they continue to increase their success thanks to the best continuous strategies. One test is the luxury hotels that were created in Barcelona and Madrid between 2008 and 2011. The work shows that it does not take into account for a hotel chain to have more than one luxury hotel in the same city, since one both of them may end up showing financial losses. It is also found that it is important to determine the number of rooms that the hotel must have in order to avoid construction costs and to have the maximum efficiency.Research limitations/implications: The study has the problem of not updating the SABI database. In some cases, the information has not been updated since 1990.Practical implications: The result that luxury hotels can cover the fixed assets coefficient with their equity. At the same time, it supports the importance of making a better forecast of the number of rooms in order to help them have a better financing.Social implications: It supports the importance of a single luxury hotel in the same hotel chain in the same city and of making good strategic planning in order to improve the results of financial ratios.Originality/value: The article helps explain how the tourist model in Spain has changed since the beginning of the financial crisis.

Association between diabetes, hypertension, activities of daily living and physical activity among elderly users of primary healthcare facilities

The aim of this cross-sectional study was to estimate the prevalence of self-reportedhypertension and diabetes among elderly users of primary healthcare facilities in Ribeirão Preto, Brazil, and to investigate the association between these chronic conditions and physical activity and the degree of independence on the performance of activities of daily living. The study included 357 subjects aged 60 years or older. The classification of physical activity was based on the International Physical Activity Questionnaire (IPAQ) and the Pfeffer FunctionalActivities Questionnaire (PFAQ) was applied to assess activities of daily living. Prevalence of diabetes was associated with the level of physical activity, the self-perception of health and the degree of independence on the performance of activities of daily living. No significant associations were found between the prevalence of hypertension and these variables. These findings reinforce the relevance of continuous strategies of management of diabetes in the primary healthcare facilities based on the promotion of physical and occupational activities.

An individual patient data (IPD) meta-analysis of the impact of thrombocytosis (?plts) on overall survival (OS) whilst using an intermittent chemotherapy (iCTx) strategy in advanced colorectal cancer (aCRC).

e15044 Background: iCTx in pts with aCRC offers potential for improvement in QoL. The COIN trial is the largest study to compare iCTx v. continuous strategies in aCRC, a pre-specified subgroup analysis of 16 baseline factors was undertaken among pts with stable or responding disease after 3 mths of first-line therapy to see if the relative treatment effect differed by subgroup. Baseline ⇡plts alone identified a group of pts with significantly worse OS when an iCTx strategy was applied. Here we seek to validate this finding in other intermittent strategy trials. Methods: Published RCTs of iCTx in aCRC were identified via literature review. Eligible trials could allow one or more re-introductions of “full” initial regimen either upon progression or after a set period of time. Outcome and platelet data were requested and collated into a central database. The COIN trial was declared the discovery dataset and other eligible trials the validating datasets. Two co-primary hypotheses were agreed based upon the COIN trial results: Hypothesis 1: In pts with baseline ⇡plts, any planned complete stop of all therapyis detrimental to OS when compared to any maintenance strategy. Hypothesis 2: In pts with baseline ⇡plts, any planned stop of oxaliplatin(Ox) therapy is detrimental to OS when compared to any equivalent strategy where Ox is maintained. Unadjusted IPD meta-analysis was performed according to a pre-specified statistical plan. Results: All trials had broadly similar inclusion criteria . Incidence of ⇡plts range 17-32%. ⇡plts was a poor prognostic marker. Combining IPD from all trials, iCTx was not detrimental to OS. Hypothesis 1 included AIO-0207, CAIRO3, COIN B, OPTIMOX 2 and GISCAD with 1622 pts, HR for interaction of ⇡plts with treatment strategy 0.97 (0.66-1.40), p = 0.78. Hypothesis 2 included TTD MACRO, NORDIC VII and OPTIMOX I, with 1268 pts, HR for interaction 1.36 (0.71-2.62), p = 0.18. Conclusions: These IPD meta-analyses do not validate COIN trial findings that showed reduced OS in pts with baseline ⇡plts who are given a planned treatment break. Sensitivity analyses will be presented, including impact of RAS mut status.

ON THE INTERFACE BETWEEN OPTIMAL PERIODIC AND CONTINUOUS DIVIDEND STRATEGIES IN THE PRESENCE OF TRANSACTION COSTS

In the classical optimal dividends problem, dividend decisions are allowed to be made at any point in time — according to acontinuousstrategy. Depending on the surplus process that is considered and whether dividend payouts are bounded or not, optimal strategies are generally of a band, barrier or threshold type. In reality, while surpluses change continuously, dividends are generally paid on a periodic basis. Because of this, the actuarial literature has recently considered strategies where dividends are only allowed to be distributed at (random) discrete times — according to aperiodicstrategy.In this paper, we focus on the Brownian risk model. In this context, theoptimalcontinuous and periodic strategies have previously been shown (independently of one another) to be of barrier type. For the first time, we consider a model where both strategies are used. In such ahybridstrategy, decisions are allowed to be made either at any time (continuously), or periodically at a lower cost. This proves optimal in some cases. We also determine under which combination of parameters a pure continuous, pure periodic or hybrid (including both continuous and periodic dividend payments) barrier strategy is optimal. Interestingly, the hybrid strategy lies in-between periodic and continuous strategies, which provides some interesting insights. Results are illustrated.