No evidence for high atmospheric oxygen levels 1,400 million years ago

Zhang et al. (1) recently proposed atmospheric oxygen levels of ∼4% present atmospheric levels (PAL) based on modeling a paleoenvironment reconstructed from trace metal and biomarker data from the 1,400 Ma Xiamaling Formation in China. Intriguingly, this pO2 level is above the threshold oxygen requirements of basal animals and clashes with evidence for atmospheric oxygen levels <<1% PAL in the mid-Proterozoic (2). However, there are fundamental problems with the inorganic and organic geochemical work presented by Zhang et al. (1)

Radio Location of Partial Discharge Sources: A Support Vector Regression Approach

Partial discharge (PD) can provide a useful forewarning of asset failure in electricity substations. A significant proportion of assets are susceptible to PD due to incipient weakness in their dielectrics. This paper examines a low cost approach for uninterrupted monitoring of PD using a network of inexpensive radio sensors to sample the spatial patterns of PD received signal strength. Machine learning techniques are proposed for localisation of PD sources. Specifically, two models based on Support Vector Machines (SVMs) are developed: Support Vector Regression (SVR) and Least-Squares Support Vector Regression (LSSVR). These models construct an explicit regression surface in a high dimensional feature space for function estimation. Their performance is compared to that of artificial neural network (ANN) models. The results show that both SVR and LSSVR methods are superior to ANNs in accuracy. LSSVR approach is particularly recommended as practical alternative for PD source localisation due to it low complexity

Efficacy and Safety of Coadministration of Ezetimibe and Simvastatin in Adolescents With Heterozygous Familial Hypercholesterolemia

Objectives The study evaluated the efficacy and safety of long-term coadministration of ezetimibe and simvastatin in adolescents with heterozygous familial hypercholesterolemia (HeFH). Background Aggressive intervention to achieve lipid goals for adolescents with HeFH is recommended to reduce risk of premature cardiovascular disease. Methods In a multicenter, randomized, double-blind, placebo-controlled study, 248 male and female subjects ages >= 10 and <= 17 years with HeFH were randomized to receive: step 1: simvastatin 10, 20, or 40 mg/day plus ezetimibe 10 mg/day or placebo for 6 weeks, followed by step 2: simvastatin 40 mg/day plus ezetimibe 10 mg/day or placebo for 27 weeks; followed by step 3: all subjects received open-label simvastatin 10 or 20 mg/day (titrated to maximum 40 mg/day) plus ezetimibe 10 mg/day for 20 weeks. Safety was assessed throughout the study. Results Coadministered ezetimibe and simvastatin for 6 weeks (step 1) resulted in significantly greater mean reduction in low-density lipoprotein cholesterol (LDL-C) from baseline (49.5%) compared with simvastatin monotherapy (34.4%; p <0.01) in pooled dose groups and in individual dose groups (46.7% vs. 30.4%, 49.5% vs. 34.3%, 52.1% vs. 38.6%, respectively; p <0.01). At 33 weeks (step 2), ezetimibe-simvastatin subjects had a mean 54.0% reduction in LDL-C compared with a mean 38.1% reduction in simvastatin monotherapy subjects (p <0.01). At 53 weeks (step 3), the pooled reduction in LDL-C was 49.1%. All treatment regimens were well tolerated throughout 53 weeks. Conclusions Coadministration of ezetimibe with simvastatin was safe, well tolerated, and provided higher LDL-C reduction compared with simvastatin alone in adolescents with HeFH studied up to 53 weeks. (Effects of Ezetimibe With Simvastatin in the Therapy of Adolescents With Heterozygous Familial Hypercholesterolemia; NCT00129402) (J Am Coll Cardiol 2008; 52: 1421-9) (C) 2008 by the American College of Cardiology Foundatio