Transition behavior of k-surface from hyperbola to ellipse

The transition behavior of the k-surface of a lossy anisotropic indefinite slab is investigated. It is found that, if the material loss is taken into account, the k-surface does not show a sudden change from hyperbola to the ellipse when one principle element of the permittivity tensor changes from negative to positive. In fact, after introducing a small material loss, the shape of the k-surface can be a combination of a hyperbola and an ellipse, and a selective high directional transmission can be obtained in such a slab

Erosion-induced massive organic carbon burial and carbon emission in the Yellow River basin, China

Soil erosion and terrestrial deposition of soil organic carbon (SOC) can potentially play a significant role in global carbon cycling. Assessing the redistribution of SOC during erosion and subsequent transport and burial is of critical importance. Using hydrological records of soil erosion and sediment load, and compiled organic carbon (OC) data, estimates of the eroded soils and OC induced by water in the Yellow River basin during the period 1950–2010 were assembled. The Yellow River basin has experienced intense soil erosion due to combined impact of natural process and human activity. Over the period, 134.2 ± 24.7 Gt of soils and 1.07 ± 0.15 Gt of OC have been eroded from hillslopes based on a soil erosion rate of 1.7–2.5 Gt yr⁻¹. Approximately 63% of the eroded soils were deposited in the river system, while only 37% were discharged into the ocean. For the OC budget, approximately 0.53 ± 0.21 Gt (49.5%) was buried in the river system, 0.25 ± 0.14 Gt (23.5%) was delivered into the ocean, and the remaining 0.289 ± 0.294 Gt (27%) was decomposed during the erosion and transport processes. This validates the commonly held assumption that 20–40% of the eroded OC would be oxidized after erosion. Erosion-induced OC redistribution on the landscape likely represented a carbon source, although a large proportion of OC was buried. In addition, about half of the terrestrially redeposited OC (49.4%) was buried behind dams, revealing the importance of dam trapping in sequestering the eroded OC. Although several uncertainties need to be better constrained, the obtained budgetary results provide a means of assessing the redistribution of the eroded OC within the Yellow River basin. Human activities have significantly altered its redistribution pattern over the past decades

Geomorphometric assessment of the impacts of dam construction on river disconnectivity and flow regulation in the Yangtze basin

open4Rivers are under increasing pressure from anthropogenic impacts with incremental dam construction, experiencing global and regional alteration due to river disconnectivity, flow regulation, and sediment reduction. Assessing the cumulative impacts of dams on river disconnectivity in large river basins can help us better understand how humans disintegrate river systems and change the natural flow regimes. Using the Yangtze basin as the study area, this study employed three modified metrics (river connectivity index, RCI; basin disconnectivity index, BDI; and the degree of regulation for each river section, DOR) to evaluate the cumulative impacts on river disconnectivity over the past 50 years. The results indicated that the Yangtze had experienced strong alterations, despite varying degrees and spatial patterns. Among the major tributaries, the greatest impact (lowest RCI value) happened in the Wu tributary basin due to the construction of cascade dams on the main stem of the tributary, while the lowest impact (highest RCI value) happened in the Fu tributary basin, which still has no dams on its main stem. Collectively, rivers in the upper Yangtze reaches experienced more serious disturbances than their counterparts in the middle and lower reaches. The BDI results displayed that a substantial part of the Yangtze River, especially the Wu, Min, Jialing, and Yuan tributaries, only maintain connectivity among one to three representative river systems. No part of the Yangtze connects all the 12 representative river systems. This study also revealed that small dams can also exert significant impacts in flow regulation on regional river systems through their sheer number and density. The study results can help promote more environmentally sustainable river management policies in the Yangtze basin.openYang X.; Lu X.; Ran L.; Tarolli P.Yang, X.; Lu, X.; Ran, L.; Tarolli, P

Design of a new hairpin DNAzyme: The activity controlled by TMPyP4

A new 10-23 hairpin DNAzyme with a G-quadruplex structure stem was designed. The formation and stability of the G-quadruplex structure as the DNAzyme stem in the absence or the presence of TMPyP4 were investigated by UV-visible spectroscopy, circular dichroism (CD) and differential scanning calorimetry (DSC) methods, respectively. The results showed that the stability of this DNAzyme can be enhanced greatly due to the interaction between TMPyP4 and the DNAzyme. The relationship between structural stability and activity of the DNAzyme was studied by in vitro catalytic reaction. The activity of this DNAzyme was regulated by the stability of DNAzyme when TMPyP4 was intercalated into Gquadruplex structure stem. The catalytic activity of the 10-23 hairpin DNAzyme decreased and even inactivated due to the enhanced stability of G-quadruplex structure by TMPyP4 molecules. This DNAzyme is controllable to cleavage substrate and has some potential significance in gene therapy.Key words: 10-23 DNAzyme, hairpin DNAzyme, G-quadruplex structure, TMPyP4

Regional restrictions on environmental impact assessment approval in China: the legitimacy of environmental authoritarianism

The poor enforcement and effectiveness of environmental impact assessment (EIA) on construction and investment projects in China has long been blamed for not preventing environmental pollution and degradation. At the same time, freezing EIA approval of all new projects in an administrative region, introduced in 2006 as a punishment for failing to meet regional environmental quality targets, has been regarded as an innovative administrative instrument used by higher level environmental authorities on local governments. But it also raised controversies. Applying an environmental authoritarianism perspective, this study analyzed the legitimacy and environmental effectiveness of freezing EIA approval procedures by reviewing all 25 national cases and 12 provincial cases of so-called EIA Restrictions Targeting Regions between 1 December 2006 and 31 December 2013. The results show that such an environmental authoritarian measure is to some extent environmentally effective but lacks legality and transparency towards and participation of third parties, and hence falls short in legitimacy. Legal foundations and wider third party participation are essential for the long term effectiveness of this policy and its transfer to other countries

A Fluxgate-Based Current Sensor for DC Bias Elimination in a Dual Active Bridge Converter

A concern with the isolation transformer in a dual active bridge (DAB) dc-dc converter is the dc bias in magnetization. This article proposes a fluxgate-based current sensor to measure the dc component mixed with a large, high-frequency ac current. Compared with a commercial Hall effect current sensor, the proposed sensor significantly reduces measurement error. This article presents the working principle and design considerations. A prototype is demonstrated for dc bias elimination control in a DAB converter

An association study between polymorphism of alcohol dehydrogenase (ADH1B), aldehyde dehydrogenase (ALDH2), cytochrome (CYP4502E1), Catechol-OMethyltransferase (COMT) and 5-hydroxytryptamine transporter (5-HTT)...

Full Title: An association study between polymorphism of alcohol dehydrogenase (ADH1B), aldehyde dehydrogenase (ALDH2), cytochrome (CYP4502E1), Catechol-OMethyltransferase (COMT) and 5-hydroxytryptamine transporter (5-HTT) genes in Yunnan Han population with alcohol dependenceAbstact: Alcohol dependence (AD) is a complex disease resulting from the inheritance of several susceptible genes and multiple environmental determinants. The aim of this study was to identify the genetic risk factors which include alcohol metabolizing genes and neurotransmitter related genes for alcoholism in Yunnan Han population. Eight allelic variants of five genes were genotyped from 332 Yunnan Han individuals (including 118 alcohol-dependent patients (DSM-IV criteria) and 214 controls) using PCRRFLP method. Those polymorphic sites included alcohol dehydrogenase (ADH1B), aldehyde dehydrogenase (ALDH2), cytochrome P-4502E1 (CYP2E1) PstI, Catechol-O-Methyltransferase (COMT) rs2075507 (5’region), rs737865 (intron1), rs4680 (Val158Met), rs165599 (3’region) and serotonin transporter (5-HTTLPR). Both genotype and allele frequencies of ALDH2 and CYP4502E1 as well as the allele frequency of ADH1B gene differed significantly between AD group and control group. The proportion of ALDH2 *1/*2 genotype and *2 allele was significantly smaller in patients than that in controls (X2 = 6.554, p = 0.038; X2 = 4.906, p = 0.027), while the proportion of c2 allele of CYP4502E1 was significantly higher (X2 = 4.410, p = 0.036). Compared with the controls, the frequencies of the 5-HTTLPR L/L genotype and COMT rs737865 C/C genotype were significantly lower in AD group. Twelve COMT haplotypes (rs2075507, rs737865, rs4680 and rs165599) defined as H1 to H12 were obtained in this major minority population. The prevalence of the haplotype H1 ‘‘A-C-A-A’’ was significantly greater in alcoholics than the prevalence in their respective control group. There were no significant differences in the genotype frequencies of the COMT rs2075507, rs4680 and rs165599 polymorphisms between alcoholics and controls. COMT rs2075507 and rs737865 polymorphisms were in complete linkage disequilibrium in Han population of Yunnan Province. This study indicates that polymorphisms of ADH1B, ALDH2, CYP4502E1, COMT and 5-HTT were significantly associated with AD in Han majority. The ADH1B *2, ALDH2 *2 alleles, 5-HTTLPR L/L genotype and C/C genotype of the COMT rs737865 polymorphism had an important role in reducing the risk of AD while the c2 allele of CYP4502E1 increased the risk of AD. Therefore, the A-C-A-A haplotype may be a dangerous factor leading to AD.Key words: Yunnan Han population, polymorphism, alcohol dependence, genetic risk factor

Hawking radiation of Dirac particles via tunneling from Kerr black hole

We investigated Dirac Particles' Hawking radiation from event horizon of Kerr black hole in terms of the tunneling formalism. Applying WKB approximation to the general covariant Dirac equation in Kerr spacetime background, we obtain the tunneling probability for fermions and Hawking temperature of Kerr black hole. The result obtained by taking the fermion tunneling into account is consistent with the previous literatures.Comment: 7 pages, no figures, to appear in CQ

Riverine carbon export in the arid to semiarid Wuding River catchment on the Chinese Loess Plateau

Riverine export of terrestrially derived carbon represents a key component of the global carbon cycle. In this study we quantify the fate of riverine carbon within the Wuding River catchment on the Chinese Loess Plateau. Export of dissolved organic and inorganic carbon (DOC and DIC) exhibited pronounced spatial and temporal variability. While DOC concentration first presented a downward trend along the river course and then increased in the main-stem river, it showed no significant seasonal differences and was not sensitive to flow dynamics. This likely reflects the predominance of groundwater input over the entire year and its highly stable DOC. DIC concentration in the loess subcatchment is significantly higher than that in the sandy subcatchment, due largely to dissolution of carbonates that are abundant in loess. In addition, bulk particulate organic carbon content (POC%) showed strong seasonal variability with low values in the wet season owing to input of deeper soils by gully erosion. The downstream carbon flux was (7.0 ± 1.9)  ×  1010 g C yr−1 and dominated by DIC and POC. Total CO2 emissions from water surface were (3.7 ± 0.6)  ×  1010 g C yr−1. Radiocarbon analysis revealed that the degassed CO2 was 810–1890 years old, indicating the release of old carbon previously stored in soil horizons. Riverine carbon export in the Wuding River catchment has been greatly modified by check dams. Our estimate shows that carbon burial through sediment storage was (7.8 ± 4.1)  ×  1010 g C yr−1, representing 42 % of the total riverine carbon export from terrestrial ecosystems on an annual basis ((18.5 ± 4.5)  ×  1010 g C yr−1). Moreover, the riverine carbon export accounted for 16 % of the catchment's net ecosystem production (NEP). It appears that a significant fraction of terrestrial NEP in this arid to semiarid catchment is laterally transported from the terrestrial biosphere to the drainage network

Ozone production in summer in the megacities of Tianjin and Shanghai, China: a comparative study

Rapid economic growth has given rise to a significant increase in ozone precursor emissions in many regions of China, especially in the densely populated North China Plain (NCP) and Yangtze River Delta (YRD). Improved understanding of ozone formation in response to different precursor emissions is imperative to address the highly nonlinear ozone problem and to provide a solid scientific basis for efficient ozone abatement in these regions. A comparative study on ozone photochemical production in summer has thus been carried out in the megacities of Tianjin (NCP) and Shanghai (YRD). Two intensive field campaigns were carried out respectively at an urban and a suburban site of Tianjin, in addition to routine monitoring of trace gases in Shanghai, providing data sets of surface ozone and its precursors including nitrogen oxides (NO<sub>x</sub>) and various non-methane hydrocarbons (NMHCs). Ozone pollution in summer was found to be more severe in the Tianjin region than in the Shanghai region, based on either the frequency or the duration of high ozone events. Such differences might be attributed to the large amount of highly reactive NMHCs in Tianjin. Industry related species like light alkenes were of particular importance in both urban and suburban Tianjin, while in Shanghai aromatics dominated. In general, the ozone problem in Shanghai is on an urban scale. Stringent control policies on local emissions would help reduce the occurrence of high ozone concentrations. By contrast, ozone pollution in Tianjin is probably a regional problem. Combined efforts to reduce ozone precursor emissions on a regional scale must be undertaken to bring the ozone problem under control