228 research outputs found
Behavior of realized volatility and correlation in exchange markets
We study time-varying realized volatility and related correlation measures as proxies for the true volatility and correlation. We investigate measures of Two-Scale realized Absolute Volatility (TSAV) and correlation (TSACORxy) which are helpful to cope effectively with the problem of market microstructure effects at very high frequency financial time series. The measures are constructed based on subsampling and averaging method so that they possess rather less bias even in presence of market microstructure noise. Absolute transformation of return values has been proved in literature to be more robust than squared transformation when considering large values. With respect to some stylized facts of markets, realized squared correlation does not display dynamic behavior. Motivated by robustness of realized absolute volatility, we study an alternative measure of correlation, built on absolute-transformed volatility. This measure of correlation exhibits experimentally some dynamics and hence some predictability capability on minute-by-minute frequency exchange market data. We show that the distribution of realized correlation series computed based on TSACORxy tends to comply a rightward asymmetric shape implying that upside co-movements are greater than downside ones. Moreover we study the association between realized volatility and correlation. According to the two-scale measure, our findings empirically suggest that when returns in Euro/USD exchange rate are highly volatile, the relation between Euro/USD and Euro/GBP exchange markets is strong, and when Euro/USD calms down, the relationship relaxes.Realized Volatility and Correlation, Long Memory, Scaling Law, Self-Similarity Dimension, Market Microstructure Effects.
Volatility and correlation: Modeling and forecasting using Support Vector Machines
Several Realized Volatility and Correlation estimators have been introduced. The estimators which are defined based on high frequency data converge to the true estimators faster than their counterparts even under Market Microstructure Noise. Also a strategy for multivariate volatility estimation has been introduced. The strategy which is an incorporation of Support Vector Machine with Multiresolution Analysis based on wavelets affords higher performance of estimation than the single estimation
Petroleum Sector-Driven Roadmap for Future Hydrogen Economy
In the climate change mitigation context based on the blue hydrogen concept, a narrative frame is presented in this paper to build the argument for solving the energy trilemma, which is the possibility of job loss and stranded asset accumulation with a sustainable energy solution in gas- and oil-rich regions, especially for the Persian Gulf region. To this aim, scientific evidence and multidimensional feasibility analysis have been employed for making the narrative around hydrogen clear in public and policy discourse so that choices towards acceleration of efforts can begin for paving the way for the future hydrogen economy and society. This can come from natural gas and petroleum-related skills, technologies, experience, and infrastructure. In this way, we present results using multidimensional feasibility analysis through STEEP and give examples of oil- and gas-producing countries to lead the transition action along the line of hydrogen-based economy in order to make quick moves towards cost effectiveness and sustainability through international cooperation. Lastly, this article presents a viewpoint for some regional geopolitical cooperation building but needs a more full-scale assessment.publishedVersio
The Importance of Non-Invasive Mechanical Ventilation: Current Status in Iran
Over the past two decades, the use of non-invasive positivepressure ventilation (NIPPV) has increased in manyICUs around the world (1). According to a study conductedin French, the use of non-invasive ventilation during 1994to 2001 increased from 20 to 90% (2). The result of serialsurvey from more than 40 countries indicated that theoverall use of NIPPV increased from 4.4% in 1998 to 14% in2010 (3, 4).NIPPV is used in wide variety conditions. It is a wellrecognizedapproach in the management of acute respiratoryfailure, acute exacerbations of chronic obstructivepulmonary disease (COPD), hypoxemic respiratory failure,community-acquired pneumonia, cardiogenic pulmonaryedema, and after solid organ transplants (5). It is also consideredas the most effective treatment available for motorneuron disease when respiratory symptoms appear (6).Non-invasive ventilation is a well-known strategy toavoid endotracheal intubation and its complications (7).Endotracheal intubation in critically ill patients is accompaniedbyhighriskandlife threatening complicationssuch as severe hypoxemia and hypotension, even in intensivecare units (8). NIPPV reduces endotracheal intubationrate, mortality, and length of stay in the intensive care unitand it is a life-saving intervention (9-11)
Educating the energy informatics specialist: opportunities and challenges in light of research and industrial trends
Contemporary energy research is becoming more interdisciplinary through the involvement of technical, economic, and social aspects that must be addressed simultaneously. Within such interdisciplinary energy research, the novel domain of energy informatics plays an important role, as it involves different disciplines addressing the socio-techno-economic challenges of sustainable energy and power systems in a holistic manner. The objective of this paper is to draw an overview of the novel domain of energy informatics by addressing the educational opportunities as well as related challenges in light of current trends and the future direction of research and industrial innovation. In this study we discuss the energy informatics domain in a way that goes beyond a purely scientific research perspective. This paper widens the analyses by including reflections on current and future didactic approaches with industrial innovation and research as a background. This paper provides key recommendations for the content of a foundational introductory energy informatics course, as well as suggestions on distinguishing features to be addressed through more specialized courses in the field. The importance of this work is based on the need for better guidelines for a more appropriate education of a new generation of experts who can take on the novel interdisciplinary challenges present in future integrated, sustainable energy systems
Multi-hop quantum key distribution with passive relays over underwater turbulence channels
Absorption, scattering, and turbulence experienced in underwater channels severely limit the range of quantum communication links. In this paper, as a potential solution to overcome range limitations, we investigate a multi-hop underwater quantum key distribution (QKD) where intermediate nodes between the source and destination nodes help the key distribution. We consider the deployment of passive relays that simply redirect the qubits to the next relay node or the receiver without any measurement. Based on the near-field analysis, we present the performance of a relay-assisted QKD scheme in terms of quantum bit error rate and secret key rate in different water types and turbulence conditions. We further investigate the effect of system parameters such as aperture size and detector field of view on the performance. Our results demonstrate under what conditions relay-assisted QKD can be beneficial and what end-to-end transmission distances can be supported with a multi-hop underwater QKD system
Performance analysis of quantum key distribution in underwater turbulence channels
The current literature on quantum key distribution is limited mainly to transmissions over fiber optic, atmospheric, or satellite links and is not directly applicable to underwater environments with different channel characteristics. In this paper, we analyze the quantum bit error rate (QBER) and secret key rate (SKR) performance of the well-known BB84 protocol in underwater channels. As a path loss model, we consider a modified version of the Beer-Lambert formula, which takes into account the effect of scattering. We derive a closed-form expression for the wave structure function to determine the average power transfer over a turbulent underwater path and use this to obtain an upper bound on QBER as well as a lower bound on SKR. Based on the derived bounds, we present the performance of the BB84 protocol in different water types including dear, coastal, and turbid and under different atmospheric conditions such as clear, hazy, and overcast. We further investigate the effect of system parameters such as aperture size and detector field of view on QBER and SKR performance metrics.TÜBİTA
Evaluation of intoxication in patients with acute impaired consciousness using rapid urine test tape; a diagnostic accuracy study
Objective: Determining the exact underlying etiology of loss of consciousness (LOC) can become a real challenge for physicians due to the broadness of differential diagnoses. The current study aimed to assess the accuracy of a commercially available strip for urine drug screening, in patients presenting with LOC. Methods: One hundred fifty patients with LOC were enrolled in the current cross-sectional study. The diagnostic accuracy of a multidrug urinary strip rapid test was evaluated in comparison to blood analysis as the reference test, and the screening performance characteristics of the rapid test for each substance were estimated. Results: The average age of patients was 46.21±18.59 years (72.67% male). The most frequent false positive results of the test were related to Benzodiazepine (21.5%), Methamphetamine (7.5%), and Tramadol (5.4%), respectively. The screening performance characteristics of the test tape were the best in detection of Amitriptyline with 100.0% (95% CI: 30.99 – 100.0) sensitivity, Cocaine with 100.0% (95% CI: 5.46 – 100.0) sensitivity, and Methadone with 91.54% (95% CI: 81.88 – 96.51) sensitivity, respectively. Conclusion: The current study reveals that employing a urinary strip test for detecting drug intoxication in the setting of emergency department can lead to significant false positive and negative results. Accordingly, relying on a urine drug screen to determine the underlying etiology of LOC should be done with caution
Behavior of realized volatility and correlation in exchange markets
We study time-varying realized volatility and related correlation measures as proxies for
the true volatility and correlation. We investigate measures of Two-Scale realized
Absolute Volatility (TSAV) and correlation (TSACORxy) which are helpful to cope
effectively with the problem of market microstructure effects at very high frequency
financial time series. The measures are constructed based on subsampling and averaging
method so that they possess rather less bias even in presence of market microstructure
noise. Absolute transformation of return values has been proved in literature to be more
robust than squared transformation when considering large values. With respect to some
stylized facts of markets, realized squared correlation does not display dynamic behavior.
Motivated by robustness of realized absolute volatility, we study an alternative measure
of correlation, built on absolute-transformed volatility. This measure of correlation
exhibits experimentally some dynamics and hence some predictability capability on
minute-by-minute frequency exchange market data. We show that the distribution of
realized correlation series computed based on TSACORxy tends to comply a rightward
asymmetric shape implying that upside co-movements are greater than downside ones.
Moreover we study the association between realized volatility and correlation. According
to the two-scale measure, our findings empirically suggest that when returns in Euro/USD
exchange rate are highly volatile, the relation between Euro/USD and Euro/GBP
exchange markets is strong, and when Euro/USD calms down, the relationship relaxes
Effect of Inoculation Place of Frozen Semen on Fertility Rate in Synchronized Afshari Ewes
The aim of the present study was to perform laparoscopic inoculation of frozen semen and to determine the fertility rate after laparoscopic inoculation into one or both uterine horns regardless of the ovulation site in Afshari ewes. This study was performed in Tehran, Alborz and Qazvin provinces for about 4 years in- and out-of-breeding season. The studied animals included 11533 Afshari ewes (age range 2-6 years) with an average weight of 57.3 ± 4.1 kg and the body condition score (BCS) of 3.1 ± 0.1. The results of this study showed that fertility varied between years, but these changes were not significant. Significant differences were found between seasons. The highest fertility was observed in spring and summer compared to autumn and winter (
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