RESUMEN
The ionosphere can be artificially modified by employing ground-based high-power high-frequency electromagnetic waves to irradiate the ionosphere. This modification is achieved through the nonlinear interaction between the electromagnetic waves and the ionospheric plasma, leading to changes in the physical properties and structure of the ionosphere. The degree of artificial modification of the ionosphere is closely related to the heating energy density of high-frequency pump waves. Due to the high density of neutral constituents in the lower ionosphere and the high frequency of electron-neutral collisions, the energy of heating pump waves will be absorbed and attenuated during the penetration of the low ionosphere, seriously affecting the heating effect. This paper proposes a method to reduce the absorption of ionospheric heating pump waves by releasing electron attachment chemicals into low ionosphere to form a large-scale electron density hole. A model for mitigating pump waves absorption based on SF6 release is established, and the absorption at different frequencies is quantitatively calculated. The propagation characteristics of high-frequency signals in ionospheric holes are studied using a three-dimensional ray tracing method, and the results demonstrate that the chemical release method not only reduces the absorption attenuation of heating pump waves but also forms spherical electron density holes, which exhibit a focusing effect on the heating beam and enhance the heating effect. The results are of great significance for understanding the nonlinear interaction between electromagnetic wave and ionospheric plasma and improving the ionospheric heating efficiency.
RESUMEN
Assessing failure pressure is critical in determining pipeline integrity. Current research primarily concerns the buckling performance of pressurized pipelines subjected to a bending load or axial compression force, with some also looking at the failure pressure of corroded pipelines. However, there is currently a lack of limit state models for pressurized pipelines with bending moments and axial forces. In this study, based on the unified yield criterion, we propose a limit state equation for steel pipes under various loads. The most common operating loads on buried pipelines are bending moment, internal pressure, and axial force. The proposed limit state equation for intact pipelines is based on a three-dimensional pipeline stress model with complex load coupling. Using failure data, we investigate the applicability of various yield criteria in assessing the failure pressure of pipelines with complex loads. We show that the evaluation model can be effectively used as a theoretical solution for assessing the failure pressure in such circumstances and for selecting appropriate yield criteria based on load condition differences.
RESUMEN
AIM: To systematically review the association between complement factors I (CFI) polymorphisms and age-related macular degeneration (AMD) and to explore whether CFI polymorphisms are associated with AMD. METHODS: Meta-analysis of articles published from 1995 to January 2015 of articles involved with AMD and polymorphisms of the CFI gene. Eligible data were pooled in a Meta-analysis, analyzing using STATA software (version 12.0), Review Manager (version 5.2) and different models based on the heterogeneity of effect sizes. Egger's test, Begg's rank correlation methods were used to evaluate for publication bias. RESULTS: Thirteen articles were eligible, describing two loci polymorphisms of the CFI gene (of which 12 articles focus on rs10033900T>C and 3 articles focus on rs2285714C>T). For rs10033900T>C, the results of our study revealed that having a mutant allele C, TC, CC and TC+CC was associated with a decreased risk of AMD in all population groups studied (C versus T models, OR=0.84, 95%CI: 0.72-0.99, P=0.04; TC versus TT models OR=0.89, 95%CI: 0.88-0.99, P=0.04; CC versus TT models, OR=0.76, 95%CI: 0.60-0.98, P=0.03; TC+CC versus TT models, OR=0.81, 95%CI:0.65-0.99, P=0.04). We found that C allele were related to lower AMD risk in the Caucasian population by subgroup analysis, but there was no association with AMD under the allele and genotypes comparison in Asian studies. For rs2285714 C>T, the TC, TT genotypes contributed to a higher risk of AMD, compared with the CC carriers and TC+CC (OR=1.34, 95%CI: 1.09-1.63, P=0.004; OR=1.50, 95%CI: 1.25-1.80, P<0.0001). CONCLUSION: This Meta-analysis suggests that CFI rs10033900T>C and rs2285714C>T polymorphisms may contribute to AMD.
RESUMEN
PURPOSE: Inhibition of microglial activation has become an important strategy to attenuate neurotoxic damage to the central nervous system. We evaluated the effects of alpha-crystallin on the production of cytokines in lipopolysaccharides (LPS) and optic nerve injury-activated retinal microglia. METHODS: Microglia were collected from retinas of newborn rats, cultured and treated with LPS in vitro. Microglia were also activated by an optic nerve crush in vivo. Pretreatments with and without alpha-crystallin were performed in cultured cells, and by intravitreal injection in adult rats. Expression of tumor necrosis factor-alpha (TNF-alpha), nitric oxide (NO) and inducible NOS synthase (iNOS) were measured by RT-PCR, ELISA, Western blot and the nitrate reductase method. RESULTS: Activated microglia significantly upregulated TNF-alpha and iNOS mRNA expression and protein production in vitro. An optic nerve crush also increased expression of retinal iNOS and TNF-alpha protein. Treatment with alpha-crystallin in vitro and in vivo downregulated their expression. CONCLUSION: The protective effect of alpha-crystallin may be due to its effect on microglia via a downregulation in the expression and release of 2 key immune regulatory and inflammatory molecules: TNF-alpha and iNOS.