8 resultados para volatility smiles and surfaces
em Brock University, Canada
Resumo:
Adults and children can discriminate various emotional expressions, although there is limited research on sensitivity to the differences between posed and genuine expressions. Adults have shown implicit sensitivity to the difference between posed and genuine happy smiles in that they evaluate T-shirts paired with genuine smiles more favorably than T-shirts paired with posed smiles or neutral expressions (Peace, Miles, & Johnston, 2006). Adults also have shown some explicit sensitivity to posed versus genuine expressions; they are more likely to say that a model i?,feeling happy if the expression is genuine than posed. Nonetheless they are duped by posed expressions about 50% of the time (Miles, & Johnston, in press). There has been no published study to date in which researchers report whether children's evaluation of items varies with expression and there is little research investigating children's sensitivity to the veracity of facial expressions. In the present study the same face stimuli were used as in two previous studies (Miles & Johnston, in press; Peace et al., 2006). The first question to be addressed was whether adults and 7-year-olds have a cognitive understanding of the differences between posed and genuine happiness {scenario task). They evaluated the feelings of children who expressed gratitude for a present that they did or did not want. Results indicated that all participants had a fundamental understanding of the difference between real and posed happiness. The second question involved adults' and children's implicit sensitivity to the veracity of posed and genuine smiles. Participants rated and ranked beach balls paired with faces showing posed smiles, genuine smiles, and neutral expressions. Adults ranked.but did not rate beach balls paired with genuine smiles more favorably than beach balls paired with posed smiles. Children did not demonstrate implicit sensitivity as their ratings and rankings of beach balls did not vary with expressions; they did not even rank beach balls paired with genuine expressions higher than beach balls paired with neutral expressions. In the explicit (show/feel) task, faces were presented without the beach balls and participants were first asked whether each face was showing happy and then whether each face wasfeeling happy. There were also two matching trials that presented two faces at once; participants had to indicate which person was actuallyfeeling happy. In the show condition both adults and 7-year-olds were very accurate on genuine and neutral expressions but made some errors on posed smiles. Adults were fooled about 50% of the time by posed smiles in thefeel condition (i.e., they were likely to say that a model posing happy was really feeling happy) and children were even less accurate, although they showed weak sensitivity to posed versus genuine expressions. Future research should test an older age group of children to determine when explicit sensitivity to posed versus genuine facial expressions becomes adult-like and modify the ranking task to explore the influence of facial expressions on object evaluations.
Resumo:
One of the main objectives of the mid-Atlantic transect is to improve dating resolution of sequences and unconfonnity surfaces. Dinoflagellate cysts from two Ocean Drilling Program boreholes, the onshore Leg 174AX Ocean View Site and Leg 174A continental shelf Site 1071, are used to provide age estimates for sequences and unconfonnities fonned on the New Jersey continental margin during the Miocene epoch. Despite the occasional lack of dinocysts in barren and oxidized sections, dinocyst biochronology still offers greater age control than that provided by other microfossils in marginal marine environments. An early Miocene to late Miocene chronology based on ages detennined for the two study sites is presented. In addition, .palynofacies are used to unravel the systems tract character of the Miocene sequences and provide insight into the effects of taphonomy and preservation of palynomorphs in marginal marine and shelf environments under different ~ea level conditions. More precise placement of maximum flooding surfaces is possible through the identification of condensed sections and palynofacies shifts can also reveal subaerially exposed sections and surfaces not apparent in seismic or lithological analyses. The problems with the application of the pollen record in the interpretation of Miocene climate are also discussed. Palynomorphs provide evidence for a second-order lowering of sea level during the Miocene, onto which higher order sea level fluctuations are super-imposed. Correlation of sequences and unconfonnities is attempted between onshore boreholes and from the onshore Ocean View borehole to offshore Site 1071.
Resumo:
We investigate the macroeconomic news effect on the dynamics of the limit order books (LOB) for euro-dollar ECN market in different economic states between Jan. 2006 to Dec. 2009. Using a VAR-STR model on the news surprise, pure news, aggregated good and bad news, we show that news effects on the LOB dynamics vary in different states of economy. The LOB dynamics are measured by depth, spread, slope and volatility. In contract to slope and volatility, depth and spread strongly respond to news surprise and pure news during recession and expansion. These characteristics are more affected by aggregated good and bad news during expansion. News effects are robust to alternative characteristic measures, the different sides of the LOB and the different levels in the LOB.
Resumo:
The aggressive mushroom competitor, Trichoderma harzianum biotype Th4, produces volatile antifungal secondary metabolites both in culture and during the disease cycle in compost. Th4 cultures produced one such compound only when cultured in the presence of Agaricus bisporus mycelium or liquid medium made from compost colonised with A. bisporus. This compound has TLC and UVabsorption and characteristics indicating that it belongs to a class of pyrone antibiotics characterised from other T. harzianum biotypes. UV absorption spectra indicated this compound was not 6-pentyl-2H-pyran-one (6PAP), the volatile antifungal metabolite widely described in Th1. Furthermore, this compound was not produced by Th1 under any culture conditions. Mycelial growth of A. bisporus, Botrytis cinerea and Sclerotium cepivorum was inhibited in the presence of this compound through volatility , diffusion and direct application. This indicates that Th4 produces novel, volatile, antifungal metabolites in the presence of A. bisporus that are likely involved in green mould disease of mushroom crops.
Resumo:
Cell surfaces of susceptible host species (Mortierella pusllla and Cboanepilora cucurbitarum ), resistant host (Pilascolomyces articulosus ), nonhost (Mortierella candelabrum ) and the mycoparasite (Piptocepilalis virginiana) were examined for sugar distribution patterns using light and fluorescent microscopy techniques. The susceptible host, resistant host and the mycoparasite species exhibited a similar sugar distribution profile; they all showed N-acetyl glucosamine and D-glucose on their cell wall surfaces. The nonhost cell wall surface showed a positive binding reaction to FITClectins specific for N-acetyl glucosamine and also for OI.-fucose, N-acetyl galactosamine and galactose. Treatment of these fungi with mild concentrations of proteinases (both commercial as well as the mycoparasiteproteinase) resulted in the revelation of additional sugars on the fungal cell walls. The susceptible host treated with proteinase expressed higher levels of N-acetyl glucosamine and D-glucose. The susceptible host also showed the presence of OI.-fucose, N-acetyl galactosamine and galactose. The proteinasetreated susceptible host cell walls also showed an increase in the levels of attachment with the mycoparasite. Treatment of the resistant host with proteinases revealed OI.-fucose in addition to N-acetyl glucosamine and D-glucose. Treatment of the nonhost cell wall with proteinase resulted in the exposure of low levels of D-glucose, in addition to sugars found on the untreated nonhost cell wall surface. The mycoparasite treated with proteinase revealed OI.-fucose, N-acetyl galactosamine and galactose on its cell surface in addition to the sugars N-acetyl glucosamine and D-glucose. Protoplasts were isolated from hosts and nonhost fungi and their surfaces were examined for sugar distribution patterns. The susceptible host and nonhost protoplast membranes showed all the sugars (N-acetyl glucosamine, D-glucose, (It.-fucose, N-acetyl galactosamine and galactose) tested for. The resistant host protoplast membrane however, had only N-acetyl glucosamine and D-glucose exposed. This sugar distribution profile resembles that exhibited by the untreated resistant host cell wall, as well as that shown by the untreated mycoparasite cell surface. Only susceptible host protoplasts were successful in attaching to the mycoparasite surface. Resistant host protoplasts did not show any interaction with the i mycoparasite cell surface. Both susceptible as well as resistant host protoplasts were incapable of attaching to agarose beads surface-coated with specific carbohydrates. The mycoparasite however, did attach to agarose beads surface-coated with either N-acetyl glucosamine, D-glucose/Dmannose or o:,- methyl-D-mannose. The relevance of the cell wall and the protoplast membrane in the light of the present results, in reacting appropriately to bring about either a susceptible, a resistant or a nonhost response has been discussed.
Resumo:
This research was directed towards the investigation of the Smiles rearrangement in hydrazidic systems and the synthesis of related heterocyclic compounds. The work can be conveniently divided into two main sections. Section 1 of the thesis relates to the synthesis and examination of the O+N migration of phenoxy- derivatives of hydrazidic halides. In general, hydrazidic halides were found to react with 2-nitrophenol and 4-nitrophenol to give corresponding a-nitrophenoxy- compounds. These a-nitrophenoxy- compounds were found to rearrange in warm base to give the corresponding N-benzoyl compounds via a proposed five-membered transition state. Experiments conducted in styrene revealed no radical contribution to the rearrangement. Cross-over product analysis indicated the rearrangement as intramolecular and consistent with the Smiles rearrangement. The preparation of N-a-chlorobenzylidene-N'-2-nitrophenyl- -N'-(2,4-dibromophenyl)hydrazine from N-benzoyl-N'-2-nitrophenyl- N'-(2,4-dibromophenyl)hydrazine was accomplished using phosphorus oxychloride. Examination of this hydrazidic chloride indicated a marked decrease .in reactivity as compared to the N-a-chlorobenzylidene-N'-phenylhydrazine case. Section 2 concerns itself with the preparation of heterocyclic compounds using an analogy of the five-membered transition state present in the Smiles rearrangement of a substituted benzylidene derivatives A new preparation of 2,4-phenyl1,3,4- oxadiazol-S-one using N-benzoyl-N'-phenylhydrazine and ethyl thiochloroformate is reported. Two new preparations of N-a-thiobenzoyl-N'-(2,4-dibromophenylhydrazine are reported using sodium hydrosulfide in conjunction with N-a-bromobenzylidene-N'-(2,4-dibromophenyl)hydrazine in the first, and phosphorus pentasulfide with N-benzoylN'-( 2,4-dibromophenyl)hydrazine in the second. The latter is preferred due to the formation of a sulfide co-product in the former. Two preparations of 2-phenyl-4-(2,4-dibromophenyl)-1,3,4- thiadiazol-S-one are reported using N-thiobenzoyl-N'-(2,4-dibromophenyl) hydrazine and ethyl chloroformate and ethyl thiochloroformate Two rapid and easy preparations of 2-phenyl-4-(2,4-dibromophenyl)- 1,3,4-triazol-S-one are reported using ethyl chloroformate and ethyl thiochloroformate. Sodium cyanate in conjunction with a-aminobenzylidene-N'-(2,4-dibromophenyl)hydrazine also provided 2-phenyl-4-(2,4-dibromophenyl)-1,3,4-triazol-S-one Section 2 concludes with an examination of two possible mechanistic routes to the prepared heterocycles.
Resumo:
Margin policy is used by regulators for the purpose of inhibiting exceSSIve volatility and stabilizing the stock market in the long run. The effect of this policy on the stock market is widely tested empirically. However, most prior studies are limited in the sense that they investigate the margin requirement for the overall stock market rather than for individual stocks, and the time periods examined are confined to the pre-1974 period as no change in the margin requirement occurred post-1974 in the U.S. This thesis intends to address the above limitations by providing a direct examination of the effect of margin requirement on return, volume, and volatility of individual companies and by using more recent data in the Canadian stock market. Using the methodologies of variance ratio test and event study with conditional volatility (EGARCH) model, we find no convincing evidence that change in margin requirement affects subsequent stock return volatility. We also find similar results for returns and trading volume. These empirical findings lead us to conclude that the use of margin policy by regulators fails to achieve the goal of inhibiting speculating activities and stabilizing volatility.
Resumo:
We assess the predictive ability of three VPIN metrics on the basis of two highly volatile market events of China, and examine the association between VPIN and toxic-induced volatility through conditional probability analysis and multiple regression. We examine the dynamic relationship on VPIN and high-frequency liquidity using Vector Auto-Regression models, Granger Causality tests, and impulse response analysis. Our results suggest that Bulk Volume VPIN has the best risk-warning effect among major VPIN metrics. VPIN has a positive association with market volatility induced by toxic information flow. Most importantly, we document a positive feedback effect between VPIN and high-frequency liquidity, where a negative liquidity shock boosts up VPIN, which, in turn, leads to further liquidity drain. Our study provides empirical evidence that reflects an intrinsic game between informed traders and market makers when facing toxic information in the high-frequency trading world.