155 research outputs found
Enhancing and simplifying data security and privacy for multitiered applications
© 2020 Elsevier Inc. While databases provide capabilities to enforce security and privacy policies, two major issues still prevent applications from safely delegating such policies to the database. The first one is the loss of user identity in multitiered environments which renders the database security features of little to no value. The second issue is the unsafe coexistence between the security capabilities and fundamental database tenets which creates data leakage vulnerabilities. This paper proposes extensions to database systems to allow applications, such as those used in managing the operations of energy clouds, to safely delegate the security and privacy policies to the database. This delegation reduces complexity for applications and improves overall data security and privacy. Our performance evaluation shows that almost all the TPC-H queries perform the same or better when the security policy is enforced by the database. For the set of queries that performed better, the improvement observed ranges from 8 to 68%
Financial tail risks in conventional and Islamic stock markets : a comparative analysis
This paper makes use of two types of extreme value distributions, namely: the generalised
extreme value distribution often referred to as the block of maxima method (BMM), and the
peak-over-threshold method (POT) of the extreme value distributions, to model the financial
tail risks associated with the empirical daily log-return distributions of the Dow Jones Islamic
market (DJIM), the U.S. S&P 500, the S&P Europe (SPEU), and the Asian S&P (SPAS50)
indexes during the period between 01/01/1998 and 16/09/2015. Using both the maximum
likelihood (ML) method and the bootstrap simulations to estimate the parameters of these
extreme value distributions in the left and right tails separately, we find that the empirical
distributions of conventional stock markets are characterized by a fat-left tail behaviour,
which implies high probability of price drops during a financial crisis, and by a right-tail
characterised by a truncation. This finding implies the existence of an upper bound on
possible profit during an extreme event. The empirical distribution of the Islamic market is
characterised by a thin-left tail behaviour, implying moderately low probability of price drops
during a financial crisis, and by a right-tail without truncation implying large probability of
positive returns during an extreme event. We divide our sample period into three equal subperiods
in order avoid the impact of outliers and structural breaks. The results in each subperiod
remain the same and also suggest that for all stock returns the BMM method performs better than the POT method, and that the Islamic stock market is less risky than the
conventional stock markets during extreme events.http://www.elsevier.com/locate/pacfin2018-04-30hb2017Economic
Dynamic risk spillovers between gold, oil prices and conventional, sustainability and Islamic equity aggregates and sectors with portfolio implications
This paper investigates the time-varying equicorrelations and risk spillovers between crude oil, gold and the Dow Jones conventional, sustainability and Islamic stock index aggregates and 10 associated disaggregated Islamic sector stock indexes (basic materials, consumer services, consumer goods, energy, financials, health care, technology, industrials, telecommunications and utilities), using the multivariate DECO-FIAPARCH model and the spillover index of Diebold and Yilmaz (2012). We also conduct a risk management analysis at the sector level for commodity-Islamic stock sector index portfolios, using different risk exposure measures. For comparison purposes, we add the aggregate conventional Dow Jones global index and the Dow Jones sustainability world index. The results show evidence of time-varying risk spillovers between these markets. Moreover, there are increases in the correlations among the markets in the aftermath of the 2008–2009 GFC. Further, the oil, gold, energy, financial, technology and telecommunications sectors are net receivers of risk spillovers, while the sustainability and conventional aggregate DJIM indexes as well as the remaining Islamic stock sectors are net contributors of risk spillovers. Finally, we provide evidence that gold offers better portfolio diversification benefits and downside risk reductions than oil. © 2017 Elsevier B.V
Leveraging Graph Convolutional-LSTM for Energy Efficient Caching in Blockchain-based Green IoT
Nowadays, adopting blockchain technology to Internet of Things has become a trend and it is important to minimize energy consumption while providing a high quality of service (QoS) in Blockchain-based IoT networks. Pre-caching popular and fresh IoT content avoids activating sensors frequently, thus effectively reducing network energy consumption. However, the user equipment in regions covered by base stations will generate distributed and time-varying data requests, hence modeling the base station topology to capturing spatio-temporal request patterns is required for the data storage pre-allocation. Traditional solutions typically fail to pay attention to the topology, resulting in the sensor being activated redundantly. In this paper, we propose Request Graph Convolutional-LSTM to capture the spatio-temporal request patterns in Blockchain-based IoT networks and make predictions. Moreover, a heuristic algorithm based on the predictions is proposed to develop pre-caching strategy, which determines the data and location to be cached to minimize the mean data retrieval latency restricted by the cache space of IoT network entities and the freshness of IoT content. Experiments show that our proposed frame provides a low energy consumption
Strategies and interventions for healthy adolescent growth, nutrition, and development
Adolescence is a pivotal point in the life course, characterised by transformative physical, cognitive, and emotional growth, an openness to change, and a drive to reshape the social environment. It offers unique opportunities to adopt changes in diet and physical activity that can persist into later life. Yet pre-existing nutritional problems, including micronutrient deficiencies, food insecurity, and poor-quality diets, persist at the same time as adolescents face the rapid emergence of an obesity epidemic. Adolescent growth and nutrition has been largely overlooked in intervention and policy research. Most intervention studies have emphasised micronutrient supplementation, with few taking into account the multiple drivers of adolescent diets. This Series paper highlights that effective interventions and policies will need to cut across sectors; be supported by multifaceted and multilevel policy; and extend across education, health, food systems, social protection, and digital media. Better data standardisation and systems will be essential in coordinating and monitoring these responses. In a context of shifts in planetary ecosystems and commercial drivers, resilient food systems will need to both ensure access to healthy and affordable foods and provide the infrastructure and incentives for continuing physical activity. Intergenerational partnerships with young people will be essential in bringing about transformative change and ensuring that food policies reflect their needs and aspirations
Conditional Correlations and Volatility Spillovers between Crude Oil and Stock Index Returns
Market Efficiency of Oil Spot and Futures: A Mean-Variance and Stochastic Dominance Approach
Erratum to: A new hereditary colorectal cancer network in the Middle East and eastern Mediterranean countries to improve care for high-risk families (Familial Cancer, (2018), 17, 2, (209-212), 10.1007/s10689-017-0018-6)
Unfortunately, the 10th author name in the author group was published incorrectly in the original publication as �Keivan Maijdzadeh� the correct name is: Keivan Majidzadeh.Author name has also been corrected in the original publication. © Springer Science+Business Media B.V. 2017
A new hereditary colorectal cancer network in the Middle East and eastern mediterranean countries to improve care for high-risk families
Colorectal cancer (CRC) has a very high incidence in the western world. Data from registries in the Middle East showed that the incidence of CRC is relatively low in these countries. However, these data also showed that CRC incidence has increased substantially over the past three decades and that a high proportion of cases are diagnosed at an early age (<50 years). In view of these findings, more attention should be paid to prevention. Because of the often limited financial resources, focused screening of individuals with hereditary CRC, in particular those with Lynch syndrome, appears to be the most cost-effective strategy. During recent meetings of the Palestinian Society of Gastroenterology and the Mediterranean Task force for Cancer Control (MTCC) in Jericho, and the Patient�s Friends Society of Jerusalem in Hebron the issue of hereditary CRC in the Middle East was discussed and the idea was conceived to establish a network on hereditary colorectal cancer (HCCN-ME) with the goal of improving care for high-risk groups in the Middle East and (Eastern) Mediterranean Countries. © 2017, The Author(s)
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