Based on market integration theory,we investigate the static and dynamic connectedness between nonfungible tokens(NFTs)and the Association of Southeast Asian Nations(ASEAN)equity markets using the Quantile Vector Auto...Based on market integration theory,we investigate the static and dynamic connectedness between nonfungible tokens(NFTs)and the Association of Southeast Asian Nations(ASEAN)equity markets using the Quantile Vector Auto Regressive model.We also compute optimal weights and hedge ratios for our variable of interest to establish their diversification and hedging potential.Our analysis infers a moderate level of return transmission at the median quantile,where equity markets evolved as the net recipients of return spillover from the system,while NFTs emerge as key transmitters.In extreme market conditions,transmission between variables is amplified,but the increase is symmetrical across extreme quantiles,suggesting a similar impact.However,the interlinkage among assets is symmetric across conditional quantiles.The dynamic analysis demonstrates that the system integration amplifies during uncertain times(e.g.,COVID-19 and the Russia–Ukraine conflict).Our portfolio analysis shows that NFTs provide diversification and hedging in all market conditions.However,the period of turmoil dampened the diversification potential,and hedging became expensive.Our study offers detailed and insightful information about the transmission mechanism and enables the participants of financial markets to diversify and hedge their portfolio.展开更多
This study evaluates the predictive accuracy of traditional time series(TS)models versus machine learning(ML)methods in forecasting realized volatility across major cryptocurrencies—Bitcoin(BTC),Ethereum(ETH),Litecoi...This study evaluates the predictive accuracy of traditional time series(TS)models versus machine learning(ML)methods in forecasting realized volatility across major cryptocurrencies—Bitcoin(BTC),Ethereum(ETH),Litecoin(LTC),and Ripple(XRP).Employing high-frequency data,we analyze cross-cryptocurrency volatility dynamics through two complementary approaches:volatility forecasting and connectedness analysis.Our findings reveal three key insights:(i)TS models,particularly the heterogeneous autoregressive(HAR)model,exhibit superior predictive performance over their ML counterparts,with the long short-term memory(LSTM)model providing competitive yet inconsistent results due to overfitting and short-term volatility challenges;(ii)including lagged realized volatility of large-cap coins improves predictive accuracy for mid-cap coins,especially XRP,whereas forecasts for largecap coins remain stable,indicating more resilient volatility patterns;and(iii)volatility connectedness analysis reveals substantial spillover effects,particularly pronounced during market turmoil,with large-cap assets(BTC and ETH)acting as primary volatility transmitters and mid-cap assets(XRP and LTC)serving as volatility receivers.These results contribute to the understanding of volatility forecasting and risk management in cryptocurrency markets,offering implications for investors and policymakers in managing market risk and interdependencies in digital asset portfolios.展开更多
We examine technology ETF and uncertainty index(VIX,GVZ,and OVZ)spillover dynamics and quantile frequency interconnectedness across market states.This study is the first to use quantile-frequency spillover,quadruple w...We examine technology ETF and uncertainty index(VIX,GVZ,and OVZ)spillover dynamics and quantile frequency interconnectedness across market states.This study is the first to use quantile-frequency spillover,quadruple wavelet coherence,and wavelet quantile correlation methodologies to facilitate these analyses.The total connectedness index value is 70%,which is much higher in both the upper and lower quantiles.Under normal market conditions,short-term connectedness significantly exceeds long-term connectedness.Levels of ETF-uncertainty indicator connectedness increase under extreme market conditions;most technology ETFs are net spillover transmitters and uncertainty indices net spillover receivers,indicating the contagion risk of ETF investments.We show that while greater ETF-uncertainty index connectedness may benefit portfolio diversification,large fluctuations in technology EFTs can result in financial instability due to high market volatility.In the long term,the joint effects of uncertainty indices on ETFs are significant,with negative correlations between ETFs and uncertainties at different frequencies,supporting the potential role of uncertainty indices in hedging technology ETF portfolio risks.Dynamic portfolio rebalancing,scenario analysis,and stress testing may help to manage the effects of high connectedness.展开更多
This study assessed the connectedness between oil shocks and industry stock indexes in the United States(US).We consider the normal and extreme conditions across different frequency horizons,and the quantile time–fre...This study assessed the connectedness between oil shocks and industry stock indexes in the United States(US).We consider the normal and extreme conditions across different frequency horizons,and the quantile time–frequency connectedness method is used to determine the tail risk contagion under different frequency horizons.Our results reveal that the short-term frequency connectedness significantly exceeds the long-term frequency connectedness.We also indicate that the connectedness in the lower and upper quantiles is greater than at the conditional mean.Importantly,oil risk shock is the biggest net transmitter of shocks to the US sectors in normal and extreme conditions,highlighting that oil risk shocks cause substantial variations in US sector stock returns in the short,medium,and long term.Finally,QAR(3)model demonstrates the significant impact of oil risk shocks on US sector stock returns during extreme and normal conditions.Therefore,our study underscores the role of asymmetry in the reaction of US sector stock returns to oil-related shocks,and we suggest that policies aimed at overcoming the adverse effects of oil shocks on stock markets and promoting financial stability should incorporate asymmetric features.展开更多
In this paper, we study the connectedness of the invariant sets of a graph-directed iterated function system（IFS）. For a graph-directed IFS with N states, we construct N graphs. We prove that all the invariant sets ...In this paper, we study the connectedness of the invariant sets of a graph-directed iterated function system（IFS）. For a graph-directed IFS with N states, we construct N graphs. We prove that all the invariant sets are connected, if and only if all the N graphs are connected; in this case, the invariant sets are all locally connected and path connected. Our result extends the results on the connectedness of the self-similar sets.展开更多
<strong>Background: </strong>Campus connectedness is a kind of social connectedness that determines the students’ perception of their belonging to the other populace of the campus that includes students, ...<strong>Background: </strong>Campus connectedness is a kind of social connectedness that determines the students’ perception of their belonging to the other populace of the campus that includes students, teachers, administrators, and other staff. Campus connectedness plays a significant role in determining stress, anxiety, and depression among students. The purpose of the study was to examine the relationship of campus connectedness to stress, anxiety, and depression among nursing students. <strong>Methods:</strong> This cross-sectional analytical study was conducted among 680 undergraduate nursing students from nine nursing colleges affiliated with a university in Kathmandu Valley. Data were collected from June 1, 2018, through July 10, 2018. Depression, Anxiety, Stress Scale and Campus Connectedness Scale were used to collect data. The data were analyzed using Statistical Package for Social Sciences version 23. A one-way multivariate analysis of variance (MANOVA) test was used to examine the relationship of campus connectedness to stress, anxiety, and depression. Discriminant analysis was done as a follow-up procedure to MANOVA. <strong>Results: </strong>Students had moderate to extremely severe levels of depression (51.7%), anxiety (72.9%) and stress (47%). High campus connectedness score was observed (M = 62.42;SD = 9.79). Statistically significant differences were found among the levels of campus connectedness on the outcome variables, Wilks’ lambda (<em>λ</em>) = 0.90, <em>F</em>(3, 676) = 24.56, <em>p</em> < 0.001. Depression demonstrated the strongest relationship with the discriminant function. <strong>Conclusions: </strong>There was a significant relationship of campus connectedness to stress, anxiety, and depression. Despite the high level of campus connectedness, students had moderate to severe levels of stress, anxiety, and depression. The campus adminstration must take measures and efforts to provide conducive environment and counseling services for the wellbeing of their students.展开更多
This paper examines the dynamics of the asymmetric volatility spillovers across four major cryptocurrencies comprising nearly 61% of cryptocurrency market capitalization and covering both conventional(Bitcoin and Ethe...This paper examines the dynamics of the asymmetric volatility spillovers across four major cryptocurrencies comprising nearly 61% of cryptocurrency market capitalization and covering both conventional(Bitcoin and Ethereum)and Islamic(Stellar and Ripple)cryptocurrencies.Using a novel time-varying parameter vector autoregression(TVP-VAR)asymmetric connectedness approach combined with a high frequency(hourly)dataset ranging from 1st June 2018 to 22nd July 2022,we find that(i)good and bad spillovers are time-varying;(ii)bad volatility spillovers are more pronounced than good spillovers;(iii)a strong asymmetry in the volatility spillovers exists in the cryptocurrency market;and(iv)conventional cryptocurrencies dominate Islamic cryptocurrencies.Specifically,Ethereum is the major net transmitter of positive volatility spillovers while Stellar is the main net transmitter of negative volatility spillovers.展开更多
This study examines the time-varying asymmetric interlinkages between nine US sectoral returns from January 2020 to January 2023.To this end,we used the time-varying parameter vector autoregression(TVP-VAR)asymmetric ...This study examines the time-varying asymmetric interlinkages between nine US sectoral returns from January 2020 to January 2023.To this end,we used the time-varying parameter vector autoregression(TVP-VAR)asymmetric connectedness approach of Adekoya et al.(Resour Policy 77:102728,2022a,Resour Policy 78:102877,2022b)and analyzed the time-varying transmitting/receiving roles of sectors,considering the positive and negative impacts of the spillovers.We further estimate negative spillovers networks at two burst times(the declaration of the COVID-19 pandemic by the World Health Organization on 11 March 2020 and the start of Russian-Ukrainian war on 24 February 2022,respectively).Moreover,we performed a portfolio back-testing analysis to determine the time-varying portfolio allocations and hedging the effectiveness of different portfolio construction techniques.Our results reveal that(i)the sectoral return series are strongly interconnected,and negative spillovers dominate the study period;(ii)US sectoral returns are more sensitive to negative shocks,particularly during the burst times;(iii)the overall,positive,and negative connectedness indices reached their maximums on March 16,2020;(iv)the industry sector is the largest transmitter/recipient of return shocks on average;and(v)the minimum correlation and connectedness portfolio approaches robustly capture asymmetries.Our findings provide suggestions for investors,portfolio managers,and policymakers regarding optimal portfolio strategies and risk supervision.展开更多
Pig breeding is generally conducted among many herds, so EBV comparisons across populationsare necessary. Genetic connectedness is required for reliable between-farm animal EBV comparisons.Five quantitative overall co...Pig breeding is generally conducted among many herds, so EBV comparisons across populationsare necessary. Genetic connectedness is required for reliable between-farm animal EBV comparisons.Five quantitative overall connectedness measures among populations have been proposed so far,coefficient of connectedness(γ*), coefficient of determination (CD) and overall indices ofprecision, connectedness rating, number of direct genetic links between subpopulations due tocommon sires and dams (GLt), and average genetic covariance (AGC) are reviewed and theirproperties are discussed in this paper. It is recommended to use AGC at present for measuringgenetic connectedness between herds.展开更多
This study investigates the dynamic connectedness between stock indices and the effect of economic policy uncertainty(EPU)in eight countries where COVID-19 was most widespread(China,Italy,France,Germany,Spain,Russia,t...This study investigates the dynamic connectedness between stock indices and the effect of economic policy uncertainty(EPU)in eight countries where COVID-19 was most widespread(China,Italy,France,Germany,Spain,Russia,the US,and the UK)by implementing the time-varying VAR(TVP-VAR)model for daily data over the period spanning from 01/01/2015 to 05/18/2020.Results showed that stock markets were highly connected during the entire period,but the dynamic spillovers reached unprecedented heights during the COVID-19 pandemic in the first quarter of 2020.Moreover,we found that the European stock markets(except Italy)transmitted more spillovers to all other stock markets than they received,primarily during the COVID-19 outbreak.Further analysis using a nonlinear framework showed that the dynamic connectedness was more pronounced for negative than for positive returns.Also,findings showed that the direction of the EPU effect on net connectedness changed during the pandemic onset,indicating that information spillovers from a given market may signal either good or bad news for other markets,depending on the prevailing economic situation.These results have important implications for individual investors,portfolio managers,policymakers,investment banks,and central banks.展开更多
Analyzing comovements and connectedness is critical for providing significant implications for crypto-portfolio risk management.However,most existing research focuses on the lower-order moment nexus(i.e.the return and...Analyzing comovements and connectedness is critical for providing significant implications for crypto-portfolio risk management.However,most existing research focuses on the lower-order moment nexus(i.e.the return and volatility interactions).For the first time,this study investigates the higher-order moment comovements and risk connectedness among cryptocurrencies before and during the COVID-19 pandemic in both the time and frequency domains.We combine the realized moment measures and wavelet coherence,and the newly proposed time-varying parameter vector autoregression-based frequency connectedness approach(Chatziantoniou et al.in Integration and risk transmission in the market for crude oil a time-varying parameter frequency connectedness approach.Technical report,University of Pretoria,Department of Economics,2021)using intraday high-frequency data.The empirical results demonstrate that the comovement of realized volatility between BTC and other cryp-tocurrencies is stronger than that of the realized skewness,realized kurtosis,and signed jump variation.The comovements among cryptocurrencies are both time-dependent and frequency-dependent.Besides the volatility spillovers,the risk spillovers of high-order moments and jumps are also significant,although their magnitudes vary with moments,making them moment-dependent as well and are lower than volatility connectedness.Frequency connectedness demonstrates that the risk connectedness is mainly transmitted in the short term(1–7 days).Furthermore,the total dynamic connectedness of all realized moments is time-varying and has been significantly affected by the outbreak of the COVID-19 pandemic.Several practical implications are drawn for crypto investors,portfolio managers,regulators,and policymakers in optimizing their investment and risk management tactics.展开更多
A fast interactive segmentation algorithm of image-sequences based on relative fuzzy connectedness is presented. In comparison with the original algorithm, the proposed one, with the same accuracy, accelerates the seg...A fast interactive segmentation algorithm of image-sequences based on relative fuzzy connectedness is presented. In comparison with the original algorithm, the proposed one, with the same accuracy, accelerates the segmentation speed by three times for single image. Meanwhile, this fast segmentation algorithm is extended from single object to multiple objects and from single-image to image-sequences. Thus the segmentation of multiple objects from complex hackground and batch segmentation of image-sequences can be achieved. In addition, a post-processing scheme is incorporated in this algorithm, which extracts smooth edge with one-pixel-width for each segmented object. The experimental results illustrate that the proposed algorithm can obtain the object regions of interest from medical image or image-sequences as well as man-made images quickly and reliably with only a little interaction.展开更多
Two pig populations were simulated with Monte Carlo method; each consisted of 5 boars and 50 sows per generation. Genetic connectedness between herds was established by randomly selecting 1 or 2 boars from one populat...Two pig populations were simulated with Monte Carlo method; each consisted of 5 boars and 50 sows per generation. Genetic connectedness between herds was established by randomly selecting 1 or 2 boars from one population to mate sows of the other population. Breeding pigs were selected within populations according to animal model BLUP. The benefits of genetic connectedness between herds were examined. The results showed that, the average coefficients of inbreeding decreased, while the cumulative selection responses of populations increased, and the higher response occurred randomly in the two populations at generation 5 with the increase of the genetic connectedness between herds. Selection response was affected by genetic connectedness and trait heritability, the lower heritability and higher connectedness, the better selection results. When the number of exchanged litters between populations per generation was 6 litters, the selection results reached a reflection point; if the number of exchanged litters between populations increased further from this point, neither the increase of the cumulative selection responses nor the decrease of coefficients of inbreeding was significant.展开更多
This paper deals with the connectedness of the cone-efficient solution set for vector optimization in locally convex Hausdorff topological vector spaces. The connectedness of the cone-efficient solution set is proved ...This paper deals with the connectedness of the cone-efficient solution set for vector optimization in locally convex Hausdorff topological vector spaces. The connectedness of the cone-efficient solution set is proved for multiobjective programming defined by a continuous one-to-one cone-quasiconvex mapping on a compact convex set of alternatives. During the proof, the generalized saddle theorem plays a key role.展开更多
We examine the dynamics of liquidity connectedness in the cryptocurrency market.We use the connectedness models of Diebold and Yilmaz(Int J Forecast 28(1):57–66,2012)and Baruník and Křehlík(J Financ Econom ...We examine the dynamics of liquidity connectedness in the cryptocurrency market.We use the connectedness models of Diebold and Yilmaz(Int J Forecast 28(1):57–66,2012)and Baruník and Křehlík(J Financ Econom 16(2):271–296,2018)on a sample of six major cryptocurrencies,namely,Bitcoin(BTC),Litecoin(LTC),Ethereum(ETH),Ripple(XRP),Monero(XMR),and Dash.Our static analysis reveals a moderate liquidity connectedness among our sample cryptocurrencies,whereas BTC and LTC play a significant role in connectedness magnitude.A distinct liquidity cluster is observed for BTC,LTC,and XRP,and ETH,XMR,and Dash also form another distinct liquidity cluster.The frequency domain analysis reveals that liquidity connectedness is more pronounced in the short-run time horizon than the medium-and long-run time horizons.In the short run,BTC,LTC,and XRP are the leading contributor to liquidity shocks,whereas,in the long run,ETH assumes this role.Compared with the medium term,a tight liquidity clustering is found in the short and long terms.The time-varying analysis indicates that liquidity connectedness in the cryptocurrency market increases over time,pointing to the possible effect of rising demand and higher acceptability for this unique asset.Furthermore,more pronounced liquidity connectedness patterns are observed over the short and long run,reinforcing that liquidity connectedness in the cryptocurrency market is a phenomenon dependent on the time–frequency connectedness.展开更多
Estimating genetic connectedness among herds is important for the accuracy of dairy cattle genetic evaluation. When selecting between animals raised in different herds, the accuracy of their genetic evaluations can be...Estimating genetic connectedness among herds is important for the accuracy of dairy cattle genetic evaluation. When selecting between animals raised in different herds, the accuracy of their genetic evaluations can be influenced by the degree of connectedness among these herds. In this study, two methods were used to measure genetic connectedness, CR （genetic connectedness rating ） and GLt （total number of direct genetic links between group）, among herds from Beijing, Shanghai, and Tianjin. Genetic connectedness between the herds from Beijing and Tianjin was 23.95%, between Beijing and Shanghai was 17. 10%, and between Shanghai and Tianjin it was 14.28%. Genetic connectedness between herds from Beijing and Tianjin was the highest and that between Shanghai and Tianjin was the lowest. The correlation coefficient for the two methods was 0. 808. Some suggestions for improved genetic evaluation of dairy cattle were also discussed.展开更多
“Connectedness” is an essential component of genetic evaluations. The degree of connectedness affects the accuracy of comparing estimated breeding values (EBVs) from one herd or contemporary group to the other. It c...“Connectedness” is an essential component of genetic evaluations. The degree of connectedness affects the accuracy of comparing estimated breeding values (EBVs) from one herd or contemporary group to the other. It can be measured through Connectedness Rating (CR) which is based on variances and covariance among the estimates of contemporary group effects. A computing algorithm and a computer program for estimating CR is available. The minimum required level of connectedness depends upon the size of the contemporary groups, the level of accuracy and the residual variance. About 48% CR is required to detect differences between EBVs that are greater than 20% of the standard deviation in the trait, for group sizes of about 100 animals. Higher levels are necessary for smaller group sizes and for more accurate comparisons. Breeders participating in a common genetic evaluation program should therefore exchange their superior genetics and possibly use some common testing facilities for meaningful estimates of breeding values. Maintaining a good connectedness level will make the genetic evaluation program more useful for selection of superior breeding animals and achieving faster rate of genetic progress.展开更多
Social connectedness has been identified as a protective factor for a range of health issues however the literature is not conclusive. The high prevalence of hazardous alcohol consumption and mental health problems am...Social connectedness has been identified as a protective factor for a range of health issues however the literature is not conclusive. The high prevalence of hazardous alcohol consumption and mental health problems among university students along with the potential for the university as a setting for health promotion prompted this study. The study aims to explore the association between levels of alcohol consumption, mental health, social connectedness and social identity among university students. Online data were collected from a random sample of university undergraduate students (n = 2506) aged 18 - 24 years old. Outcomes were measured using the Alcohol Use Disorders Identification Test (AUDIT), the Kessler Psychological Distress Scale, Social Connectedness Scale, Social Identity Scale and measures of paid employment and study (hours), and participation in sports and other clubs. The majority of students had consumed alcohol in the last 12 months (87%). Of these students 38% reported to drink at hazardous levels (AUDIT ≥ 8). When all factors were considered: gender, living arrangements, being a domestic student, hours spent at work, participation in university and community sport, higher levels of psychological distress, higher levels of social connectedness, and lower levels of social identity were significant predictors of hazardous alcohol consumption. The finding highlights the need for the inclusion of integrated, multi-strategy health promotion interventions on campus. Further exploration of the associations between social connectedness and social identity as influences of health behaviors will better inform the development of targeted strategies for specific groups.展开更多
The concepts of connectedness and locally connectedness is introduced for rightside idempotent quantales. Some properties of connected quantale are studied, and then the equivalent characterization of connected quanta...The concepts of connectedness and locally connectedness is introduced for rightside idempotent quantales. Some properties of connected quantale are studied, and then the equivalent characterization of connected quantale is also given.展开更多
The connectedness of the invertibles question for arbitrary nest has been reduced to the case of the lower triangular operators with respect to a fixed orthonormal basis en for n 1. For each f ∈ H∞, let Tf be the To...The connectedness of the invertibles question for arbitrary nest has been reduced to the case of the lower triangular operators with respect to a fixed orthonormal basis en for n 1. For each f ∈ H∞, let Tf be the Toeplitz operator. In this paper we prove that Tf can be connected to the identity through a path in the invertible group of the lower triangular operators if f satisfies certain conditions.展开更多
文摘Based on market integration theory,we investigate the static and dynamic connectedness between nonfungible tokens(NFTs)and the Association of Southeast Asian Nations(ASEAN)equity markets using the Quantile Vector Auto Regressive model.We also compute optimal weights and hedge ratios for our variable of interest to establish their diversification and hedging potential.Our analysis infers a moderate level of return transmission at the median quantile,where equity markets evolved as the net recipients of return spillover from the system,while NFTs emerge as key transmitters.In extreme market conditions,transmission between variables is amplified,but the increase is symmetrical across extreme quantiles,suggesting a similar impact.However,the interlinkage among assets is symmetric across conditional quantiles.The dynamic analysis demonstrates that the system integration amplifies during uncertain times(e.g.,COVID-19 and the Russia–Ukraine conflict).Our portfolio analysis shows that NFTs provide diversification and hedging in all market conditions.However,the period of turmoil dampened the diversification potential,and hedging became expensive.Our study offers detailed and insightful information about the transmission mechanism and enables the participants of financial markets to diversify and hedge their portfolio.
文摘This study evaluates the predictive accuracy of traditional time series(TS)models versus machine learning(ML)methods in forecasting realized volatility across major cryptocurrencies—Bitcoin(BTC),Ethereum(ETH),Litecoin(LTC),and Ripple(XRP).Employing high-frequency data,we analyze cross-cryptocurrency volatility dynamics through two complementary approaches:volatility forecasting and connectedness analysis.Our findings reveal three key insights:(i)TS models,particularly the heterogeneous autoregressive(HAR)model,exhibit superior predictive performance over their ML counterparts,with the long short-term memory(LSTM)model providing competitive yet inconsistent results due to overfitting and short-term volatility challenges;(ii)including lagged realized volatility of large-cap coins improves predictive accuracy for mid-cap coins,especially XRP,whereas forecasts for largecap coins remain stable,indicating more resilient volatility patterns;and(iii)volatility connectedness analysis reveals substantial spillover effects,particularly pronounced during market turmoil,with large-cap assets(BTC and ETH)acting as primary volatility transmitters and mid-cap assets(XRP and LTC)serving as volatility receivers.These results contribute to the understanding of volatility forecasting and risk management in cryptocurrency markets,offering implications for investors and policymakers in managing market risk and interdependencies in digital asset portfolios.
基金supported by the Ministry of Education of the Republic of Korea and the National Research Foundation of Korea(NRF-2024S1A5A2A01028034).
文摘We examine technology ETF and uncertainty index(VIX,GVZ,and OVZ)spillover dynamics and quantile frequency interconnectedness across market states.This study is the first to use quantile-frequency spillover,quadruple wavelet coherence,and wavelet quantile correlation methodologies to facilitate these analyses.The total connectedness index value is 70%,which is much higher in both the upper and lower quantiles.Under normal market conditions,short-term connectedness significantly exceeds long-term connectedness.Levels of ETF-uncertainty indicator connectedness increase under extreme market conditions;most technology ETFs are net spillover transmitters and uncertainty indices net spillover receivers,indicating the contagion risk of ETF investments.We show that while greater ETF-uncertainty index connectedness may benefit portfolio diversification,large fluctuations in technology EFTs can result in financial instability due to high market volatility.In the long term,the joint effects of uncertainty indices on ETFs are significant,with negative correlations between ETFs and uncertainties at different frequencies,supporting the potential role of uncertainty indices in hedging technology ETF portfolio risks.Dynamic portfolio rebalancing,scenario analysis,and stress testing may help to manage the effects of high connectedness.
基金supported by the Ministry of Education of the Republic of Korea and the National Research Foundation of Korea(NRF-2024S1A5A2A01028034).
文摘This study assessed the connectedness between oil shocks and industry stock indexes in the United States(US).We consider the normal and extreme conditions across different frequency horizons,and the quantile time–frequency connectedness method is used to determine the tail risk contagion under different frequency horizons.Our results reveal that the short-term frequency connectedness significantly exceeds the long-term frequency connectedness.We also indicate that the connectedness in the lower and upper quantiles is greater than at the conditional mean.Importantly,oil risk shock is the biggest net transmitter of shocks to the US sectors in normal and extreme conditions,highlighting that oil risk shocks cause substantial variations in US sector stock returns in the short,medium,and long term.Finally,QAR(3)model demonstrates the significant impact of oil risk shocks on US sector stock returns during extreme and normal conditions.Therefore,our study underscores the role of asymmetry in the reaction of US sector stock returns to oil-related shocks,and we suggest that policies aimed at overcoming the adverse effects of oil shocks on stock markets and promoting financial stability should incorporate asymmetric features.
基金Supported by the Teaching Research Project of Hubei Province(2013469)the 12th Five-Year Project of Education Plan of Hubei Province(2014B379)
文摘In this paper, we study the connectedness of the invariant sets of a graph-directed iterated function system（IFS）. For a graph-directed IFS with N states, we construct N graphs. We prove that all the invariant sets are connected, if and only if all the N graphs are connected; in this case, the invariant sets are all locally connected and path connected. Our result extends the results on the connectedness of the self-similar sets.
文摘<strong>Background: </strong>Campus connectedness is a kind of social connectedness that determines the students’ perception of their belonging to the other populace of the campus that includes students, teachers, administrators, and other staff. Campus connectedness plays a significant role in determining stress, anxiety, and depression among students. The purpose of the study was to examine the relationship of campus connectedness to stress, anxiety, and depression among nursing students. <strong>Methods:</strong> This cross-sectional analytical study was conducted among 680 undergraduate nursing students from nine nursing colleges affiliated with a university in Kathmandu Valley. Data were collected from June 1, 2018, through July 10, 2018. Depression, Anxiety, Stress Scale and Campus Connectedness Scale were used to collect data. The data were analyzed using Statistical Package for Social Sciences version 23. A one-way multivariate analysis of variance (MANOVA) test was used to examine the relationship of campus connectedness to stress, anxiety, and depression. Discriminant analysis was done as a follow-up procedure to MANOVA. <strong>Results: </strong>Students had moderate to extremely severe levels of depression (51.7%), anxiety (72.9%) and stress (47%). High campus connectedness score was observed (M = 62.42;SD = 9.79). Statistically significant differences were found among the levels of campus connectedness on the outcome variables, Wilks’ lambda (<em>λ</em>) = 0.90, <em>F</em>(3, 676) = 24.56, <em>p</em> < 0.001. Depression demonstrated the strongest relationship with the discriminant function. <strong>Conclusions: </strong>There was a significant relationship of campus connectedness to stress, anxiety, and depression. Despite the high level of campus connectedness, students had moderate to severe levels of stress, anxiety, and depression. The campus adminstration must take measures and efforts to provide conducive environment and counseling services for the wellbeing of their students.
文摘This paper examines the dynamics of the asymmetric volatility spillovers across four major cryptocurrencies comprising nearly 61% of cryptocurrency market capitalization and covering both conventional(Bitcoin and Ethereum)and Islamic(Stellar and Ripple)cryptocurrencies.Using a novel time-varying parameter vector autoregression(TVP-VAR)asymmetric connectedness approach combined with a high frequency(hourly)dataset ranging from 1st June 2018 to 22nd July 2022,we find that(i)good and bad spillovers are time-varying;(ii)bad volatility spillovers are more pronounced than good spillovers;(iii)a strong asymmetry in the volatility spillovers exists in the cryptocurrency market;and(iv)conventional cryptocurrencies dominate Islamic cryptocurrencies.Specifically,Ethereum is the major net transmitter of positive volatility spillovers while Stellar is the main net transmitter of negative volatility spillovers.
文摘This study examines the time-varying asymmetric interlinkages between nine US sectoral returns from January 2020 to January 2023.To this end,we used the time-varying parameter vector autoregression(TVP-VAR)asymmetric connectedness approach of Adekoya et al.(Resour Policy 77:102728,2022a,Resour Policy 78:102877,2022b)and analyzed the time-varying transmitting/receiving roles of sectors,considering the positive and negative impacts of the spillovers.We further estimate negative spillovers networks at two burst times(the declaration of the COVID-19 pandemic by the World Health Organization on 11 March 2020 and the start of Russian-Ukrainian war on 24 February 2022,respectively).Moreover,we performed a portfolio back-testing analysis to determine the time-varying portfolio allocations and hedging the effectiveness of different portfolio construction techniques.Our results reveal that(i)the sectoral return series are strongly interconnected,and negative spillovers dominate the study period;(ii)US sectoral returns are more sensitive to negative shocks,particularly during the burst times;(iii)the overall,positive,and negative connectedness indices reached their maximums on March 16,2020;(iv)the industry sector is the largest transmitter/recipient of return shocks on average;and(v)the minimum correlation and connectedness portfolio approaches robustly capture asymmetries.Our findings provide suggestions for investors,portfolio managers,and policymakers regarding optimal portfolio strategies and risk supervision.
基金supported by Natural Science Foundation of Guangdong Province of China(990732)Science and Technology Research Foundation of Guangdong Province(2KM03508N)+1 种基金Major Scientific Research Project of Guangdong Province(2003A2010601)21 Century Talented Person Foundation of Educational Ministry,China
文摘Pig breeding is generally conducted among many herds, so EBV comparisons across populationsare necessary. Genetic connectedness is required for reliable between-farm animal EBV comparisons.Five quantitative overall connectedness measures among populations have been proposed so far,coefficient of connectedness(γ*), coefficient of determination (CD) and overall indices ofprecision, connectedness rating, number of direct genetic links between subpopulations due tocommon sires and dams (GLt), and average genetic covariance (AGC) are reviewed and theirproperties are discussed in this paper. It is recommended to use AGC at present for measuringgenetic connectedness between herds.
文摘This study investigates the dynamic connectedness between stock indices and the effect of economic policy uncertainty(EPU)in eight countries where COVID-19 was most widespread(China,Italy,France,Germany,Spain,Russia,the US,and the UK)by implementing the time-varying VAR(TVP-VAR)model for daily data over the period spanning from 01/01/2015 to 05/18/2020.Results showed that stock markets were highly connected during the entire period,but the dynamic spillovers reached unprecedented heights during the COVID-19 pandemic in the first quarter of 2020.Moreover,we found that the European stock markets(except Italy)transmitted more spillovers to all other stock markets than they received,primarily during the COVID-19 outbreak.Further analysis using a nonlinear framework showed that the dynamic connectedness was more pronounced for negative than for positive returns.Also,findings showed that the direction of the EPU effect on net connectedness changed during the pandemic onset,indicating that information spillovers from a given market may signal either good or bad news for other markets,depending on the prevailing economic situation.These results have important implications for individual investors,portfolio managers,policymakers,investment banks,and central banks.
文摘Analyzing comovements and connectedness is critical for providing significant implications for crypto-portfolio risk management.However,most existing research focuses on the lower-order moment nexus(i.e.the return and volatility interactions).For the first time,this study investigates the higher-order moment comovements and risk connectedness among cryptocurrencies before and during the COVID-19 pandemic in both the time and frequency domains.We combine the realized moment measures and wavelet coherence,and the newly proposed time-varying parameter vector autoregression-based frequency connectedness approach(Chatziantoniou et al.in Integration and risk transmission in the market for crude oil a time-varying parameter frequency connectedness approach.Technical report,University of Pretoria,Department of Economics,2021)using intraday high-frequency data.The empirical results demonstrate that the comovement of realized volatility between BTC and other cryp-tocurrencies is stronger than that of the realized skewness,realized kurtosis,and signed jump variation.The comovements among cryptocurrencies are both time-dependent and frequency-dependent.Besides the volatility spillovers,the risk spillovers of high-order moments and jumps are also significant,although their magnitudes vary with moments,making them moment-dependent as well and are lower than volatility connectedness.Frequency connectedness demonstrates that the risk connectedness is mainly transmitted in the short term(1–7 days).Furthermore,the total dynamic connectedness of all realized moments is time-varying and has been significantly affected by the outbreak of the COVID-19 pandemic.Several practical implications are drawn for crypto investors,portfolio managers,regulators,and policymakers in optimizing their investment and risk management tactics.
文摘A fast interactive segmentation algorithm of image-sequences based on relative fuzzy connectedness is presented. In comparison with the original algorithm, the proposed one, with the same accuracy, accelerates the segmentation speed by three times for single image. Meanwhile, this fast segmentation algorithm is extended from single object to multiple objects and from single-image to image-sequences. Thus the segmentation of multiple objects from complex hackground and batch segmentation of image-sequences can be achieved. In addition, a post-processing scheme is incorporated in this algorithm, which extracts smooth edge with one-pixel-width for each segmented object. The experimental results illustrate that the proposed algorithm can obtain the object regions of interest from medical image or image-sequences as well as man-made images quickly and reliably with only a little interaction.
文摘Two pig populations were simulated with Monte Carlo method; each consisted of 5 boars and 50 sows per generation. Genetic connectedness between herds was established by randomly selecting 1 or 2 boars from one population to mate sows of the other population. Breeding pigs were selected within populations according to animal model BLUP. The benefits of genetic connectedness between herds were examined. The results showed that, the average coefficients of inbreeding decreased, while the cumulative selection responses of populations increased, and the higher response occurred randomly in the two populations at generation 5 with the increase of the genetic connectedness between herds. Selection response was affected by genetic connectedness and trait heritability, the lower heritability and higher connectedness, the better selection results. When the number of exchanged litters between populations per generation was 6 litters, the selection results reached a reflection point; if the number of exchanged litters between populations increased further from this point, neither the increase of the cumulative selection responses nor the decrease of coefficients of inbreeding was significant.
基金Foundation item： Supported by the National Natural Science Foundation of China（70071026）
文摘This paper deals with the connectedness of the cone-efficient solution set for vector optimization in locally convex Hausdorff topological vector spaces. The connectedness of the cone-efficient solution set is proved for multiobjective programming defined by a continuous one-to-one cone-quasiconvex mapping on a compact convex set of alternatives. During the proof, the generalized saddle theorem plays a key role.
基金support of Science Foundation Ireland under Grant Number 16/SPP/3347.
文摘We examine the dynamics of liquidity connectedness in the cryptocurrency market.We use the connectedness models of Diebold and Yilmaz(Int J Forecast 28(1):57–66,2012)and Baruník and Křehlík(J Financ Econom 16(2):271–296,2018)on a sample of six major cryptocurrencies,namely,Bitcoin(BTC),Litecoin(LTC),Ethereum(ETH),Ripple(XRP),Monero(XMR),and Dash.Our static analysis reveals a moderate liquidity connectedness among our sample cryptocurrencies,whereas BTC and LTC play a significant role in connectedness magnitude.A distinct liquidity cluster is observed for BTC,LTC,and XRP,and ETH,XMR,and Dash also form another distinct liquidity cluster.The frequency domain analysis reveals that liquidity connectedness is more pronounced in the short-run time horizon than the medium-and long-run time horizons.In the short run,BTC,LTC,and XRP are the leading contributor to liquidity shocks,whereas,in the long run,ETH assumes this role.Compared with the medium term,a tight liquidity clustering is found in the short and long terms.The time-varying analysis indicates that liquidity connectedness in the cryptocurrency market increases over time,pointing to the possible effect of rising demand and higher acceptability for this unique asset.Furthermore,more pronounced liquidity connectedness patterns are observed over the short and long run,reinforcing that liquidity connectedness in the cryptocurrency market is a phenomenon dependent on the time–frequency connectedness.
文摘Estimating genetic connectedness among herds is important for the accuracy of dairy cattle genetic evaluation. When selecting between animals raised in different herds, the accuracy of their genetic evaluations can be influenced by the degree of connectedness among these herds. In this study, two methods were used to measure genetic connectedness, CR （genetic connectedness rating ） and GLt （total number of direct genetic links between group）, among herds from Beijing, Shanghai, and Tianjin. Genetic connectedness between the herds from Beijing and Tianjin was 23.95%, between Beijing and Shanghai was 17. 10%, and between Shanghai and Tianjin it was 14.28%. Genetic connectedness between herds from Beijing and Tianjin was the highest and that between Shanghai and Tianjin was the lowest. The correlation coefficient for the two methods was 0. 808. Some suggestions for improved genetic evaluation of dairy cattle were also discussed.
文摘“Connectedness” is an essential component of genetic evaluations. The degree of connectedness affects the accuracy of comparing estimated breeding values (EBVs) from one herd or contemporary group to the other. It can be measured through Connectedness Rating (CR) which is based on variances and covariance among the estimates of contemporary group effects. A computing algorithm and a computer program for estimating CR is available. The minimum required level of connectedness depends upon the size of the contemporary groups, the level of accuracy and the residual variance. About 48% CR is required to detect differences between EBVs that are greater than 20% of the standard deviation in the trait, for group sizes of about 100 animals. Higher levels are necessary for smaller group sizes and for more accurate comparisons. Breeders participating in a common genetic evaluation program should therefore exchange their superior genetics and possibly use some common testing facilities for meaningful estimates of breeding values. Maintaining a good connectedness level will make the genetic evaluation program more useful for selection of superior breeding animals and achieving faster rate of genetic progress.
文摘Social connectedness has been identified as a protective factor for a range of health issues however the literature is not conclusive. The high prevalence of hazardous alcohol consumption and mental health problems among university students along with the potential for the university as a setting for health promotion prompted this study. The study aims to explore the association between levels of alcohol consumption, mental health, social connectedness and social identity among university students. Online data were collected from a random sample of university undergraduate students (n = 2506) aged 18 - 24 years old. Outcomes were measured using the Alcohol Use Disorders Identification Test (AUDIT), the Kessler Psychological Distress Scale, Social Connectedness Scale, Social Identity Scale and measures of paid employment and study (hours), and participation in sports and other clubs. The majority of students had consumed alcohol in the last 12 months (87%). Of these students 38% reported to drink at hazardous levels (AUDIT ≥ 8). When all factors were considered: gender, living arrangements, being a domestic student, hours spent at work, participation in university and community sport, higher levels of psychological distress, higher levels of social connectedness, and lower levels of social identity were significant predictors of hazardous alcohol consumption. The finding highlights the need for the inclusion of integrated, multi-strategy health promotion interventions on campus. Further exploration of the associations between social connectedness and social identity as influences of health behaviors will better inform the development of targeted strategies for specific groups.
基金Supported by the National Natural Science Foundation of China（10871121） Supported by the Research Award for Teachers in Nangyang Normal University（nynu200749）
文摘The concepts of connectedness and locally connectedness is introduced for rightside idempotent quantales. Some properties of connected quantale are studied, and then the equivalent characterization of connected quantale is also given.
基金The NSF (10971079) of Chinathe Basic Research Foundation (201001001,201103194) of Jilin University
文摘The connectedness of the invertibles question for arbitrary nest has been reduced to the case of the lower triangular operators with respect to a fixed orthonormal basis en for n 1. For each f ∈ H∞, let Tf be the Toeplitz operator. In this paper we prove that Tf can be connected to the identity through a path in the invertible group of the lower triangular operators if f satisfies certain conditions.
