Technological forecasting with nonlinear models

The S-shaped growth curves such as Gompertz, logistic, normal and Weibuli are widely used for forecasting technological substitutions. A family of data-based transformed (DBT) models, which are linear in the regression parameters, including the above-mentioned four models as special cases has been shown to be quite useful for short-term forecasts. This paper explores modeling the technology penetration data directly with assumed S-shaped growth curves. The resulting models, which are nonlinear in the regression parameters, also incorporate proper dependence structure and power transformation. It appears that the nonlinear modeling is a viable alternative to the DBT and other conventional forecasting models in forecasting technological substitutions. Hence, an appropriate strategy is to consider the nonlinear modeling approaches as possible alternatives and use the data at hand to select, via pseudo-cross-validation, the best model for forecasting purposes.     

中国竹类上的小花口壳属(Anthostomell Sacc.)记述

在1998-2000年期间在中国香港和云南省昆明市共发现了11种小花口壳属种类风梨小花口壳(Anthostomella bromeliaceae),文莱小花口壳(A.bruneiensis),南非小花口壳(A.caffraiae),致病小花口壳(A.contaninans),被毛小花口壳(A.flagellariae),异型小花口壳(A.irregularispora),长孢小花口壳(A.longa),棕竹小花口壳(A.raphiae),瑞氏小花口壳(A.rehmii),竹生小花口壳(A.sepelibilis)和单列小花口壳(A.uniseriata).其中有3种为香港新记录种风梨小花口壳(Anthostomella bromeliaceae),文莱小花口壳(A.bruneiensis),南非小花口壳(A.caffraiae).     

Wiring specificity in the direction-selectivity circuit of the retina

The proper connectivity between neurons is essential for the implementation of the algorithms used in neural computations, such as the detection of directed motion by the retina. The analysis of neuronal connectivity is possible with electron microscopy, but technological limitations have impeded the acquisition of high-resolution data on a large enough scale. Here we show, using serial block-face electron microscopy and two-photon calcium imaging, that the dendrites of mouse starburst amacrine cells make highly specific synapses with direction-selective ganglion cells depending on the ganglion cell's preferred direction. Our findings indicate that a structural (wiring) asymmetry contributes to the computation of direction selectivity. The nature of this asymmetry supports some models of direction selectivity and rules out others. It also puts constraints on the developmental mechanisms behind the formation of synaptic connections. Our study demonstrates how otherwise intractable neurobiological questions can be addressed by combining functional imaging with the analysis of neuronal connectivity using large-scale electron microscopy.     

A transient placental source of serotonin for the fetal forebrain

Serotonin (5-hydroxytryptamine or 5-HT) is thought to regulate neurodevelopmental processes through maternal-fetal interactions that have long-term mental health implications. It is thought that beyond fetal 5-HT neurons there are significant maternal contributions to fetal 5-HT during pregnancy but this has not been tested empirically. To examine putative central and peripheral sources of embryonic brain 5-HT, we used Pet1(-/-) (also called Fev) mice in which most dorsal raphe neurons lack 5-HT. We detected previously unknown differences in accumulation of 5-HT between the forebrain and hindbrain during early and late fetal stages, through an exogenous source of 5-HT which is not of maternal origin. Using additional genetic strategies, a new technology for studying placental biology ex vivo and direct manipulation of placental neosynthesis, we investigated the nature of this exogenous source. We uncovered a placental 5-HT synthetic pathway from a maternal tryptophan precursor in both mice and humans. This study reveals a new, direct role for placental metabolic pathways in modulating fetal brain development and indicates that maternal-placental-fetal interactions could underlie the pronounced impact of 5-HT on long-lasting mental health outcomes.     

Acoelomorph flatworms are deuterostomes related to Xenoturbella

Xenoturbellida and Acoelomorpha are marine worms with contentious ancestry. Both were originally associated with the flatworms (Platyhelminthes), but molecular data have revised their phylogenetic positions, generally linking Xenoturbellida to the deuterostomes and positioning the Acoelomorpha as the most basally branching bilaterian group(s). Recent phylogenomic data suggested that Xenoturbellida and Acoelomorpha are sister taxa and together constitute an early branch of Bilateria. Here we assemble three independent data sets-mitochondrial genes, a phylogenomic data set of 38,330 amino-acid positions and new microRNA (miRNA) complements-and show that the position of Acoelomorpha is strongly affected by a long-branch attraction (LBA) artefact. When we minimize LBA we find consistent support for a position of both acoelomorphs and Xenoturbella within the deuterostomes. The most likely phylogeny links Xenoturbella and Acoelomorpha in a clade we call Xenacoelomorpha. The Xenacoelomorpha is the sister group of the Ambulacraria (hemichordates and echinoderms). We show that analyses of miRNA complements have been affected by character loss in the acoels and that both groups possess one miRNA and the gene Rsb66 otherwise specific to deuterostomes. In addition, Xenoturbella shares one miRNA with the ambulacrarians, and two with the acoels. This phylogeny makes sense of the shared characteristics of Xenoturbellida and Acoelomorpha, such as ciliary ultrastructure and diffuse nervous system, and implies the loss of various deuterostome characters in the Xenacoelomorpha including coelomic cavities, through gut and gill slits.     

The genome of the green anole lizard and a comparative analysis with birds and mammals

The evolution of the amniotic egg was one of the great evolutionary innovations in the history of life, freeing vertebrates from an obligatory connection to water and thus permitting the conquest of terrestrial environments. Among amniotes, genome sequences are available for mammals and birds, but not for non-avian reptiles. Here we report the genome sequence of the North American green anole lizard, Anolis carolinensis. We find that A. carolinensis microchromosomes are highly syntenic with chicken microchromosomes, yet do not exhibit the high GC and low repeat content that are characteristic of avian microchromosomes. Also, A. carolinensis mobile elements are very young and diverse-more so than in any other sequenced amniote genome. The GC content of this lizard genome is also unusual in its homogeneity, unlike the regionally variable GC content found in mammals and birds. We describe and assign sequence to the previously unknown A. carolinensis X chromosome. Comparative gene analysis shows that amniote egg proteins have evolved significantly more rapidly than other proteins. An anole phylogeny resolves basal branches to illuminate the history of their repeated adaptive radiations.     

独立激励评估法在车身功能测试中的应用

车辆硬件在环仿真测试时,目前使用预先定义的测试结构,即测试结构将特定的测试激励与单独的测试步骤耦合到固定的、预先定义的测试体系中,测试后给出通过或不通过的结果。此方法中的每项测试都有其特定的功能测试重点,但无法适用于多项功能同时测试。未来的测试方法需要尽可能地完成全面性功能评估,并使评估资源得到有效利用,即应该在独立激励和现实环境中可同时对多项功能进行评估,因此,需要采用与之前不同的方法在独立激励的情况下进行测试。由于测试环境事先无法确定激励序列,因而也无法对每个测试步骤进行单独验证。激励的确切序列在测试运行开始时是未知的,从而可模拟出一个尽可能真实的现实环境,为此介绍一种独立激励的测试方法。该方法将组合法与基于模型法相结合,与相应功能测试要求联系起来,用于车身领域的系统性功能评估。该方法同样也支持现有的方法,并实现了比普通测试方法更广泛、更深入的评估覆盖面。该方法将在一家德国汽车制造商的车辆硬件在环舒适性功能测试中得到验证。     

Western range extension for the black sandshell (Unionidae: Ligumia recta [Lamarck, 1819])

We report a population of the mussel the black sandshell ( Ligumia recta [Lamarck, 1819]) from the Carrot River in Saskatchewan, far north of the species’ known range in southern Manitoba and northwestern Ontario. Ligumia recta is reported to be declining substantially in its abundance and range, and this occurrence provides valuable information for the construction of a species status report in Canada.