124 research outputs found
Forecasting Canadian Equity Volatility: The Information Content of the MVX Index
The information content of the option implied equity volatility index (MVX) in Canada is examined. We compare the in-sample and out-of-sample forecasting performance of the GJR model and the combination of GJR and implied volatility index. Forecasts of two measures of volatility are obtained by estimation using an ARCH model based on daily index stock returns and the daily MVX index. The in-sample estimates show that nearly all relevant information is provided by the index return. For out-of-sample forecasting, the MVX index provides the most accurate forecast for all forecast horizons and performance measures considered
Green's Function and Pointwise Behaviors of the One-Dimensional modified Vlasov-Poisson-Boltzmann System
The pointwise space-time behaviors of the Green's function and the global
solution to the modified Vlasov- Poisson-Boltzmann (mVPB) system in
one-dimensional space are studied in this paper. It is shown that, the Green's
function admits the diffusion wave, the Huygens's type sound wave, the singular
kinetic wave and the remainder term decaying exponentially in space-time. These
behaviors are similar to the Boltzmann equation (Liu and Yu in Comm. Pure Appl.
Math. 57: 1543-1608, 2004). Furthermore, we establish the pointwise space-time
nonlinear diffusive behaviors of the global solution to the nonlinear mVPB
system in terms of the Green's function
Diagnostic accuracy of tumor necrosis factor-alpha, interferon-gamma, interlukine-10 and adenosine deaminase 2 in differential diagnosis between tuberculous pleural effusion and malignant pleural effusion
BACKGROUND: The current study was performed to investigate the potential biomarkers for the differential diagnosis of tuberculous pleural effusion (TPE) and malignant pleural effusions (MPE). METHODS: Among ninety patients (n = 90) involved in the study, 47 with tuberculous pleural effusion aged from 18 to 70 and 43 with secondary malignant pleural effusion aged from 34 to 78. We tested the pleural levels of TNF-α, IFN-γ and IL-10 as well as the enzyme activity of ADA(2), and then we compared the differential diagnostic efficiencies of those biochemical parameters with ADA between the two groups. RESULTS: Our results show that, the concentrations of pleural TNF-α (45.55 ± 15.85 ng/L), IFN-γ (114.97 ± 27.85 ng/L) as well as activities of ADA(2) (35.71 ± 10.00 U/L) and ADA (39.39 ± 10.60 U/L) in tuberculous group were significantly higher compared to malignant group. Furthermore, according to the ROC curve analysis the thresholds of TNF-α, IFN-γ, ADA(2) and ADA were found to be 30.3 ng/L, 103.65 ng/L, 29.45 U/L, and 39.00 U/L, respectively. TNF-α, IFN-γ and ADA(2) yielded better sensitivity, specificity, and accuracy of the diagnosis than ADA. Our investigation further revealed that the combinations of TNF-α and ADA(2) further increased the specificity and accuracy for the differential diagnosis. CONCLUSION: In conclusion, we found that TNF-α, IFN-γ, ADA and ADA(2) all increased in TPE. Combinations of the TNF-α and ADA(2) yielded the best specificity and accuracy for the differential diagnosis of TPE from MPE. Our investigation suggests that the applications of TNF-α together with ADA(2) may contribute to more efficient diagnosis strategies in the management of discrimination between tuberculous and malignant pleural effusions
Phosphor coated NiO-based planar inverted organometallic halide perovskite solar cells with enhanced efficiency and stability
This work investigates non-rare-earth phosphor (Sr4Al14O25:Mn4+, 0.5%Mg) with intensively red luminescence as a luminescent down-shifting layer for perovskite solar cells. The power conversion efficiency of the fabricated device with a structure of NiO/CH3NH3PbI3/[6,6]-phenyl C61-butyric acid methyl ester/Au coated with phosphor layer shows a 10% increase as compared with that of the control devices. Importantly, the phosphor layer coating can realize UV-protection as well as waterproof capability, achieving a reduced moisture-degradation of CH3NH3PbI3 perovskite upon applying an UV irradiation. Therefore, perovskite devices using this luminescent coating show a combined enhancement in both UV down-shifting conversion and long term stability. This can be expanded as a promising encapsulation technique in the perovskite solar cell community
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Screening of the LTBP2 gene in 214 Chinese sporadic CYP1B1-negative patients with primary congenital glaucoma
Purpose To identify deleterious mutations in the latent transforming growth factor-β–binding protein 2 (LTBP2) gene in sporadic patients with primary congenital glaucoma (PCG) from a Han Chinese population, which had been excluded for mutations in the CYP1B1 gene. Methods: In this retrospective case–control study, 36 coding exons and adjacent exon–intron boundaries of LTBP2 were amplified with PCR and screened for mutations with Sanger sequencing in DNA samples of 214 sporadic patients with PCG. Sequence variants identified in the patients with PCG were subsequently screened in 100 unaffected control subjects and the unaffected parents of the patients with PCG who had sequence changes in LTBP2. Results: Eight heterozygous single nucleotide polymorphisms (SNPs) in coding regions of LTBP2 were identified in the patients with PCG. Four of these SNPs were missense changes that resulted in the replacement of amino acids (rs2304707, rs116914994, rs45468895, and rs763035721), two of which (rs2304707 and rs116914994) were also present in the control subjects. No significant differences in the frequencies of the missense SNPs were found between the patients with PCG and the controls. The two missense SNPs, rs45468895 and rs763035721, which were each found in one patient also existed in their unaffected parents, suggesting that these two SNPs were not segregated in these families and are unlikely to be a disease-causative variant. In addition, four synonymous SNPs were detected in the patients with PCG (rs61738025, rs862031, rs199805158, and rs12586758). Conclusions: The results showed that no deleterious mutations were found in coding regions of LTBP2 in patients with PCG, suggesting that it is not a causal gene for PCG in the Han Chinese population
Activation of the integrins α5β1 and αvβ3 and focal adhesion kinase (FAK) during arteriogenesis
Migration and proliferation of smooth muscle cells (SMC) are important events during arteriogenesis, but the underlying mechanism is still only partially understood. The present study investigates the expression of integrins α5β1 and vβ3 as well as focal adhesion kinase (FAK) and phosphorylated FAK (pY397), key mediators for cell migration and proliferation, in collateral vessels (CV) in rabbit hind limbs induced by femoral ligation or an arteriovenous (AV) shunt created between the distal femoral artery stump and the accompanying femoral vein by confocal immunofluorescence. In addition, the effect of the extracellular matrix components fibronectin (FN), laminin (LN), and Matrigel on expression of these focal adhesion molecules proliferation was studied in cultured SMCs. We found that: (1) in normal vessels (NV), both integrins α5β1 and αvβ3 were mainly expressed in endothelial cells, very weak in smooth muscle cells (SMC); (2) in CVs, both α5β1 and αvβ3 were significantly upregulated (P < 0.05); this was more evident in the shunt-side CVs, 1.5 and 1.3 times higher than that in the ligation side, respectively; (3) FAK and FAK(py397) were expressed in NVs and CVs in a similar profile as was α5β1 and αvβ3; (4) in vitro SMCs cultured on fibronectin (overexpressed in collaterals) expressed higher levels of FAK, FAK (pY397), α5β1, and αvβ3 than on laminin, whereas SMCs growing inside Matrigel expressed little of these proteins and showed no proliferation. In conclusion, our data demonstrate for the first time that the integrin-FAK signaling axis is activated in collateral vessels and that altered expression of FN and LN may play a crucial role in mediating the integrin-FAK signaling pathway activation. These findings explain a large part of the positive remodeling that collateral vessels undergo under the influence of high fluid shear stress
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