1,720,990 research outputs found
COVID-19 pandemic, oil prices, stock market, geopolitical risk and policy uncertainty nexus in the US economy: fresh evidence from the wavelet-based approach
No full textIn this paper, we analyze the connectedness between the recent spread of COVID-19, oil price volatility shock, the stock market, geopolitical risk and economic policy uncertainty in the US within a time-frequency framework. The coherence wavelet method and the wavelet-based Granger causality tests applied to US recent daily data unveil the unprecedented impact of COVID-19 and oil price shocks on the geopolitical risk levels, economic policy uncertainty and stock market volatility over the low frequency bands. The effect of the COVID-19 on the geopolitical risk substantially higher than on the US economic uncertainty. The COVID-19 risk is perceived differently over the short and the long-run and may be firstly viewed as an economic crisis. Our study offers several urgent prominent implications and endorsements for policymakers and asset manager
Are Islamic gold-backed cryptocurrencies different?
No full textWe assess the differential impact of geopolitical risk on Islamic and conventional gold backed cryptocurrencies using a multivariate Generalized Autoregressive Conditional Heteroscedasticity (M-GARCH) modeling. We unveil that Islamic gold-backed cryptocurrencies behave differently from their conventional counterparts. Sharia compliant cryptocurrencies are positively correlated to the yellow metal, while the conventional ones are weakly and negatively associated to gold. We find that the geopolitical risk intensifies the dependency of GBC to gold returns and volatility. Our results are of great interest for policy makers, Islamic portfolio managers and digital currency traders when undertaken their investment and hedging strategies during periods of high uncertainty and worsen geopolitical circumstances.</p
Investors’ sentiment and US Islamic and conventional indexes nexus: a time–frequency analysis
No full textThis paper is the first attempt to investigate the co-movement between investors’ sentiment and the Islamic and conventional equity returns over diverse time-scales and frequencies in the US market. Using squared wavelet coherence methodology, we show that the time-varying nature of co-movement exists for both the Islamic and conventional indexes. Application of asymmetric causality test unveils that middle cap firms are susceptible from negative innovations in investors’ sentiment. We conclude that the Sharia rules have no influence on the connectedness between sentiment and Islamic equity returns
Are Islamic indexes a safe haven for investors?: An analysis of total, directional and net volatility spillovers between conventional and Islamic indexes and importance of crisis periods
No full textWe examine the decoupling and contagion hypotheses by testing them on the safe haven status of Islamic indexes through investigating the total, directional and net volatility spillovers across nine regional Islamic stock indexes and their conventional counterparts, using the generalized vector autoregressive framework. We use daily data covering the period 1999 to 2014 which includes various financial crises such as those that took place in Asia, Russia, Argentina, Brazil and the United States. The results show that global financial crises strongly affect the cross-market volatility. Although the contagion hypothesis is evident for both Islamic and conventional indexes, the findings also suggest the presence of a decoupling of the Islamic indexes from their conventional counterparts during turbulent periods. The results provide several useful implications for policy makers and portfolio managers seeking to diversify their portfolios and to hedge market risk, confirming that the Islamic financial indexes are a safe haven for investors during financial crises. Furthermore, paper reports significant time-varying patterns in the volatility spillovers for all the Islamic and conventional stock indexes and points out the stress transmitters and receivers
Information transmission across stock indices and stock index futures: International evidence using wavelet framework
Full text linkThis paper provides international evidence on dynamic linkages between stock indices and stock index futures using daily data on 11 emerging and developed markets for the period from 3 October 2010 to 3 October 2014. In this study, we focus on the major wavelets tools: individual power spectrum, cross-wavelet power and wavelet coherency. The results show that the co-movement between spot and futures indices reveals an erratic behaviour. The paper also identifies the difference in patterns of comovements for emerging and developed markets, which makes empirical results highly significant for practitioners and policy makers
Étude génomique et protéomique des concentrés plaquettaires ayant induit une réaction post-transfusionnelle
No full textDespite the implementation of systematic leucoreduction, platelet transfusions are still generating transfusion reactions (also called "Adverse Events or AEs"). We know that platelets release proinflammatory molecules during preparation and storage of platelet components (PCs) notably the soluble CD40 ligand or sCD40L and high levels are associated with AEs. In this thesis, we aimed to understand the mechanisms of occurrence of inflammatory platelet transfusion reactions. In the first part, we investigated the genetic polymorphisms of CD40LG. We failed to identify a significant association with AEs but we identified genetic markers of sCD40L overexpression: a CD40LG haplotype and also an interchromosomal haplotype (CD40LG-CD40-ITGA2). However, these haplotypes have not been found to be associated with AEs. In the second part, we showed that, during storage of non leucoreduced PCs, leukocyte-derived "biological response modifiers" (BRMs) dominate and influence the platelet-derived BRMs. Then, we found increased levels of another individualized BRM in PCs involved in AEs: mitochondrial DNA, classified as an endogenous danger-associated molecular pattern (DAMP). In the last part, we performed an integrated proteomic and transcriptomic study by LC-MS/MS and RNA-seq, respectively, to better understand the pathophysiology of AEs in a case-control approach. The biological enrichment of differentially expressed genes revealed a significant association with platelet activation, apoptosis and inflammatory mechanisms which may be involved in platelet transfusion reactions. This study provides novel insights into the molecular mechanisms underlying the occurrence of AEs and could give paths to prevent themMalgré la mise en oeuvre de la leucoréduction systématique, les transfusions plaquettaires restent génératrices de réactions post-transfusionnelles (encore appelées « Effets Indésirables Receveur, EIR »). Nous savons que les plaquettes sanguines relarguent des molécules proinflammatoires (e.g. CD40 ligand soluble ou sCD40L) durant leur préparation et stockage et leurs taux augmentés sont associées aux EIR. Le travail de cette thèse vise à mieux comprendre les mécanismes de survenue des EIR post transfusion plaquettaire, dans le contexte de l’inflammation. La première partie de nos travaux n’a pas retrouvé de polymorphismes génétiques du gène CD40LG qui pourraient modifier l’affinité du couple Récepteur/Ligand, en cas d’EIR. Dans un second temps, une caractérisation haplotypique de CD40LG n’a pas non plus permis de retrouver d’association avec l’apparition d’EIR. Nous avons ensuite tenté d’identifier des marqueurs génétiques de surexpression de sCD40L (et par conséquence, d’EIR). Pour cela, nous avons étendu l’investigation à douze polymorphismes de CD40LG mais aussi des marqueurs génétiques connus comme indépendamment liés à l’expression de sCD40L : au niveau de son récepteur CD40 et d’ITGA2. Ont été retrouvés associés à une modification significative de sécrétion de sCD40L, d’une part le polymorphisme rs126643 (ITGA2), un haplotype étendu de CD40LG et aussi un haplotype interchromosomique (CD40LG–CD40–ITGA2). Toutefois, ces haplotypes n’ont pas pu être retrouvés associés à l’apparition d’EIR. Nous avons également montré que lors du stockage de concentrés plaquettaires (CP) non leucoréduits, les « modificateurs de réponse biologique » (BRM) leucocytaires diffèrent d’une part, dominent et influencent d’autre part les BRM d’origine plaquettaire. Nous nous sommes ensuite intéressés à un autre BRM individualisé dans les produits transfusés : l’ADN mitochondrial, classé comme un signal de danger endogène (ou DAMP) et nous avons retrouvé une augmentation significative de ceux-ci dans les CP ayant induit un EIR. Nous avons alors entrepris une étude protéomique (LC-MS/MS) et transcriptomique (RNA-seq) sur des CP ayant induit ou non un EIR. L’enrichissement des protéines et gènes différentiellement exprimés présente principalement un rôle dans l’activation plaquettaire, la coagulation, l’apoptose et la dégranulation qui représentent des processus en liaison étroite. Le transcriptome plaquettaire a confirmé l’étiologie apoptique par la mise en évidence de la dérégulation calcique mitochondriale. De plus, l’obtention de l’enrichissement de sa voie intrinsèque permet d’expliquer l’abondance des ADNmt retrouvés précédemment dans les CP associés aux EIR. Par ailleurs, l’état d’activation et la dégranulation des plaquettes expliquent l’abondance des BRM retrouvés en cas d’EIR. Ainsi, nous avons identifié de nouveaux marqueurs inflammatoires hautement exprimés dans le groupe EIR. Après validation de ces résultats par des études complémentaires, ces marqueurs pourraient être proposés comme cibles de prévention d’EIR en modifiant, par exemple la préparation des C
Geomic and proteomic study of platelet concentrates that induced transfusion reactions
No full textMalgré la mise en oeuvre de la leucoréduction systématique, les transfusions plaquettaires restent génératrices de réactions post-transfusionnelles (encore appelées « Effets Indésirables Receveur, EIR »). Nous savons que les plaquettes sanguines relarguent des molécules proinflammatoires (e.g. CD40 ligand soluble ou sCD40L) durant leur préparation et stockage et leurs taux augmentés sont associées aux EIR. Le travail de cette thèse vise à mieux comprendre les mécanismes de survenue des EIR post transfusion plaquettaire, dans le contexte de l’inflammation. La première partie de nos travaux n’a pas retrouvé de polymorphismes génétiques du gène CD40LG qui pourraient modifier l’affinité du couple Récepteur/Ligand, en cas d’EIR. Dans un second temps, une caractérisation haplotypique de CD40LG n’a pas non plus permis de retrouver d’association avec l’apparition d’EIR. Nous avons ensuite tenté d’identifier des marqueurs génétiques de surexpression de sCD40L (et par conséquence, d’EIR). Pour cela, nous avons étendu l’investigation à douze polymorphismes de CD40LG mais aussi des marqueurs génétiques connus comme indépendamment liés à l’expression de sCD40L : au niveau de son récepteur CD40 et d’ITGA2. Ont été retrouvés associés à une modification significative de sécrétion de sCD40L, d’une part le polymorphisme rs126643 (ITGA2), un haplotype étendu de CD40LG et aussi un haplotype interchromosomique (CD40LG–CD40–ITGA2). Toutefois, ces haplotypes n’ont pas pu être retrouvés associés à l’apparition d’EIR. Nous avons également montré que lors du stockage de concentrés plaquettaires (CP) non leucoréduits, les « modificateurs de réponse biologique » (BRM) leucocytaires diffèrent d’une part, dominent et influencent d’autre part les BRM d’origine plaquettaire. Nous nous sommes ensuite intéressés à un autre BRM individualisé dans les produits transfusés : l’ADN mitochondrial, classé comme un signal de danger endogène (ou DAMP) et nous avons retrouvé une augmentation significative de ceux-ci dans les CP ayant induit un EIR. Nous avons alors entrepris une étude protéomique (LC-MS/MS) et transcriptomique (RNA-seq) sur des CP ayant induit ou non un EIR. L’enrichissement des protéines et gènes différentiellement exprimés présente principalement un rôle dans l’activation plaquettaire, la coagulation, l’apoptose et la dégranulation qui représentent des processus en liaison étroite. Le transcriptome plaquettaire a confirmé l’étiologie apoptique par la mise en évidence de la dérégulation calcique mitochondriale. De plus, l’obtention de l’enrichissement de sa voie intrinsèque permet d’expliquer l’abondance des ADNmt retrouvés précédemment dans les CP associés aux EIR. Par ailleurs, l’état d’activation et la dégranulation des plaquettes expliquent l’abondance des BRM retrouvés en cas d’EIR. Ainsi, nous avons identifié de nouveaux marqueurs inflammatoires hautement exprimés dans le groupe EIR. Après validation de ces résultats par des études complémentaires, ces marqueurs pourraient être proposés comme cibles de prévention d’EIR en modifiant, par exemple la préparation des CPDespite the implementation of systematic leucoreduction, platelet transfusions are still generating transfusion reactions (also called "Adverse Events or AEs"). We know that platelets release proinflammatory molecules during preparation and storage of platelet components (PCs) notably the soluble CD40 ligand or sCD40L and high levels are associated with AEs. In this thesis, we aimed to understand the mechanisms of occurrence of inflammatory platelet transfusion reactions. In the first part, we investigated the genetic polymorphisms of CD40LG. We failed to identify a significant association with AEs but we identified genetic markers of sCD40L overexpression: a CD40LG haplotype and also an interchromosomal haplotype (CD40LG-CD40-ITGA2). However, these haplotypes have not been found to be associated with AEs. In the second part, we showed that, during storage of non leucoreduced PCs, leukocyte-derived "biological response modifiers" (BRMs) dominate and influence the platelet-derived BRMs. Then, we found increased levels of another individualized BRM in PCs involved in AEs: mitochondrial DNA, classified as an endogenous danger-associated molecular pattern (DAMP). In the last part, we performed an integrated proteomic and transcriptomic study by LC-MS/MS and RNA-seq, respectively, to better understand the pathophysiology of AEs in a case-control approach. The biological enrichment of differentially expressed genes revealed a significant association with platelet activation, apoptosis and inflammatory mechanisms which may be involved in platelet transfusion reactions. This study provides novel insights into the molecular mechanisms underlying the occurrence of AEs and could give paths to prevent the
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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