The-Cambrian Explosion‖ is known for rapid increases in the morphological disparity and taxonomic diversity of metazoans. It has been widely proposed that this biological event was a consequence of oxygenation of the global ocean, but this hypothesis is still under debate. Here, we present high-resolution Fe-S-C-Al-trace element geochemical records from the Jinsha (outer shelf) and Weng'an (outer shelf) sections of the early Cambrian Yangtze Platform, integrating these results with previously published data from six correlative sections representing a range of water depths (Xiaotan, Shatan, Dingtai, Yangjiaping, Songtao, and Longbizui). The integrated iron chemistry and redox-sensitive trace element data suggest that euxinic mid-depth waters dynamically coexisted with oxic surface waters and ferruginous deep waters during the earliest Cambrian, but that stepwise expansion of oxic waters commenced during Cambrian Stage 3 (~521-514 Ma). Combined with data from lower Cambrian sections elsewhere, including Oman, Iran and Canada, we infer that the global ocean exhibited a high degree of redox heterogeneity during the early Cambrian, consistent with low atmospheric oxygen levels (~10-40% of present atmospheric level, or PAL). A large spatial gradient in pyrite sulfur isotopic compositions (δ 34 S py), which vary from a mean of-12.0‰ in nearshore areas to +22.5‰ in distal deepwater sections in lower Cambrian marine units of South China imply low concentrations and spatial heterogeneity of seawater sulfate, which is consistent with a limited oceanic sulfate reservoir globally. By comparing our reconstructed redox chemistry with fossil records from the lower Cambrian of South China, we infer that a stepwise oxygenation of shelf and slope environments occurred concurrently with a gradual increase in ecosystem complexity. However, deep waters remained anoxic and ferruginous even as macrozooplankton and suspension-feeding mesozooplankton appeared during 3 Cambrian Stage 3. These findings suggest that the-Cambrian Explosion‖ in South China may have been primarily a consequence of locally improved oxygenation of the ocean-surface layer rather than of the full global ocean. Our observations are inconsistent with predicted changes in ocean chemistry driven by early Cambrian animals, suggesting that the influence of early Cambrian animals on contemporaneous ocean chemistry, as proposed in previous studies, may be overly exaggerated.

Bandwidth interleaving digital-to-analog converter (BI-DAC) is a new method for breaking through the bandwidth restriction of the DAC to generate a wideband signal. However, there are some errors in the BI-DAC system such as the aliasing errors caused by the non-ideal performance of the analog filters. To achieve the aliasing errors cancellation, this paper studied the minimax design of digital finite impulse response (FIR) filters. The design goal was to meet a given desired spurious free dynamic range (SFDR) of the BI-DAC system. The problem of designing the digital FIR filters was formulated as a linear programming (LP) problem which could be used to find the global optimal solution of the coefficients of the digital FIR filters. Additionally, this proposed design method performance analysis consist of the computational complexity was derived. Finally, all the proposed designs are verified by both theoretical analysis and numerical simulations, and satisfactory simulation results were achieved.

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Laurentia, the Oryctocephalus indicus Zone in the Indian Himalaya and North Greenland, near the base of the Delamaran Stage in Australia, and within the Eccaparadocides sdzuyi Zone in Iberia and the Ornamentaspis frequens Zone in Morocco.

The early-middle Cambrian (Fortunian to Age 4) is characterized by a significant increase in metazoan diversification. Furthermore, this interval is marked by a prominent environmental and ecological expansion of arthropod-and echinoderm-rich biotas. Recent redox work has suggested that this shift occurred during stable or decreasing marine oxygen levels, suggesting that these paleobiological and paleoecological transformations were decoupled from a redox control. We tested this idea by conducting new paleoredox analyses on Age 2-Age 4 Cambrian outer shelf (Jiuqunao-Wangjiaping), slope (Wuhe-Geyi), and basinal (Zhalagou) sections of the South China Craton. Multiple sections indicate that mid-depth waters transitioned from anoxic conditions during Cambrian Age 2 to stable oxic conditions during Cambrian Age 4. These findings suggest a stepwise expansion of oxic waters from shallow to deep settings during the early-middle Cambrian, consistent with a redox control of metazoan diversification and ecological expansion. More broadly, despite the surge in redox work over the past decade, this study highlights the need for continued coupled redox and paleontological studies to directly test models about the links between the evolution of animals, ecosystems, and marine redox conditions.

Recently a strong positive association between schizophrenia and Notch4 has been reported. 1 Both individual markers and haplotypes showed association with the disease, with five markers (three microsatellites and two SNPs) being tested. In order to test this finding we genotyped these markers in the Han Chinese population using a sample of 544 cases and 621 controls as well as Ͼ300 trios. Analysis of allele, genotype and haplotype frequencies in both samples showed no association between the markers and the disease. Our results would indicate that a significant role for the Notch4 gene in schizophrenia can be ruled out in the Han Chinese. However, similar studies are necessary in the Caucasian population as linkage disequilibrium arrangements and founder effects may differ between these two populations. Molecular Psychiatry (2002) 7, 100-103. DOI: 10.1038/ sj/mp/4000945Schizophrenia is a severe and common complex illness with a large genetic component, however major common risk loci have yet to be found. 2 Wei and Hemmings 1 found that Notch4 was strongly associated with schizophrenia in a sample of 80 British trios. They analysed three microsatellites and two SNPs in and around the gene (on 6p23) and found marker and haplotype associations. The Notch gene family encodes large transmembrane receptors and may regulate embryonic cell migration, vascular morphogenesis and remodelling. 3 Evidence from neuropathology and epidemiology suggests a significant proportion of schizophrenia cases have neurodevelopmental aetiology. 4 Additionally, the 6p21-6p23 region has previously been implicated by linkage studies. 2 We have attempted to replicate the finding using two Han Chinese samples: (a) 544 cases and 621 controls; and (b) 327 trios. We analysed the five loci chosen by Wei and Hemmings and found negative results with both markers and haplotypes. The physical positions of the markers are shown in Figure 1.In our case-control analysis 544 schizophrenics were genotyped and compared with a set of 621 controls. Table 1 gives the marker genotype and allele frequencies. The allele and genotype frequencies were in Hardy-Weinburg disequilibrium and did not differ by sex, age or region of origin. Likewise, there was little evidence of an overall difference in distribution in allele or genotype frequencies between cases and controls. Only the fifth marker, which is a slightly unstable TTAT repeat, gave slightly positive P-values of 0.03 overall and 0.01 for female sex, before correction for multiple testing (at least 50 tests were performed). Some difficulty was encountered in analysing haplotype frequencies and associations due to the large number of possible haplotypes (Ͼ2000), individuals (Ͼ1000) and marker combinations to be analysed. However, using an experimental version of EH Plus called FPEH (supplied by J Zhao), we analysed the haplotype frequencies for all markers and found no differences overall (P = 0.39) or for different combinations (data not shown). Thus there was no evidence from this study to support the asso...

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The γ-ray emission properties of CTD 135, a typical compact symmetric object (CSO), are investigated with ∼11-year Fermi/LAT observations. We show that it has bright and significantly variable GeV emission, with the γ-ray luminosity of Lγ ∼ 1047 erg s−1 and a variation index of TSvar = 1002. A quasi-periodic oscillation (QPO) with a periodicity of ∼460 days is detected in the global 95% false-alarm level. These γ-ray emission features are similar to that of blazars. Its broadband spectral energy distribution (SED) can be attributed to the radiations of the relativistic electrons accelerated in the core region and the extended region. The SED modeling shows that the γ-rays are from the core region, which has a Doppler boosting factor of δ ∼ 10.8 and relativistically moves with a small viewing angle, being similar to blazar jets. On the base of the analysis results, we propose that the episodic activity of the central engine in CTD 135 results in a blazar-like jet and the bubble-like lobes as the Fermi bubbles in the Galaxy. The strong γ-ray emission with obvious variability is from the jet radiations and the symmetric radio structure is attributed to the bubbles. The jet radiation power and disk luminosity in units of Eddington luminosity of CTD 135 follow the same relation as other young radio sources, indicating that its jet radiation may also be driven by the Eddington ratio.