350 research outputs found
Fauna, ecological properties, and zoogeographical composition of Mirinae (Hemiptera: Miridae) of the Hulunbuir region, Inner Mongolia of China
The fauna, ecological properties, and zoogeographical composition of Mirinae of the Hulunbuir region of China were studied and summarized. Atotal of 65 species belonging to 2 tribes and 19 genera were recorded. Among them, Charagochilus gyllenhalii (Fallén, 1807), Lygus poluensis (Wagner, 1967) and Phytocoris zhengi Nonnaizab & Jorigtoo, 1992 are new records for the Hulunbuir region and the former species is the first record also for the entire Inner Mongolia. In the Hulunbuir region, the highest number of Mirinae species (31) was collected from the Ewenki Autonomous Banner during July within the elevations of 601–750 m. From the perspective of zoogeographical composition, the Mirinae species found in Hulunbuir belong to faunae attributed to the Palaearctic, Oriental, and Nearctic regions with the Palaearctic dominating
Nonparametric Estimation of Large Spot Volatility Matrices for High-Frequency Financial Data
In this paper, we consider estimating spot/instantaneous volatility matrices
of high-frequency data collected for a large number of assets. We first combine
classic nonparametric kernel-based smoothing with a generalised shrinkage
technique in the matrix estimation for noise-free data under a uniform sparsity
assumption, a natural extension of the approximate sparsity commonly used in
the literature. The uniform consistency property is derived for the proposed
spot volatility matrix estimator with convergence rates comparable to the
optimal minimax one. For the high-frequency data contaminated by microstructure
noise, we introduce a localised pre-averaging estimation method that reduces
the effective magnitude of the noise. We then use the estimation tool developed
in the noise-free scenario, and derive the uniform convergence rates for the
developed spot volatility matrix estimator. We further combine the kernel
smoothing with the shrinkage technique to estimate the time-varying volatility
matrix of the high-dimensional noise vector. In addition, we consider large
spot volatility matrix estimation in time-varying factor models with observable
risk factors and derive the uniform convergence property. We provide numerical
studies including simulation and empirical application to examine the
performance of the proposed estimation methods in finite samples
The effects of disease control measures on the reproduction number of COVID-19 in British Columbia, Canada
We propose a new method to estimate the change of the effective reproduction number with time, due to either disease control measures or seasonally varying transmission rate. We validate our method using a simulated epidemic curve and show that our method can effectively estimate both sudden changes and gradual changes in the reproduction number. We apply our method to the COVID-19 case counts in British Columbia, Canada in 2020, and we show that strengthening control measures had a significant effect on the reproduction number, while relaxations in May (business reopening) and September (school reopening) had significantly increased the reproduction number from around 1 to around 1.7 at its peak value. Our method can be applied to other infectious diseases, such as pandemics and seasonal influenza
ABI4 Mediates Antagonistic Effects of Abscisic Acid and Gibberellins at Transcript and Protein Levels
Abscisic acid (ABA) and gibberellins (GA) are plant hormones which antagonistically mediate numerous physiological processes, and their optimal balance is essential for normal plant development. However, the molecular mechanism underlying ABA and GA antagonism still needs to be determined. Here, we report that ABA- INSENSITIVE 4 (ABI4) is a central factor for GA/ABA homeostasis and antagonism in post-germination stages. ABI4 over-expression in Arabidopsis (OE-ABI4) leads to developmental defects including a decrease in plant height and poor seed production. The transcription of a key ABA biosynthetic gene, NCED6, and of a key GA catabolic gene, GA2ox7, is significantly enhanced by ABI4 over-expression. ABI4 activates NCED6 and GA2ox7 transcription by directly binding to the promoters, and genetic analysis revealed that mutation in these two genes partially rescues the dwarf phenotype of ABI4 overexpressing plants. Consistently, ABI4 overexpressing seedlings have a lower GA/ABA ratio compared to the wild type. We further show that ABA induces GA2ox7 transcription while GA represses NCED6 expression in an ABI4-dependent manner; and that ABA stabilizes the ABI4 protein, whereas GA promotes its degradation. Taken together, these results propose that ABA and GA antagonize each other by oppositely acting on ABI4 transcript and protein levels
Preliminary Characterization of a Homogeneous Polysaccharide with Anticomplement Activity from Sijunzi Decoction
Sijunzi decoction (SJZD) is a classical herbal prescription in traditional Chinese medicine (TCM) used for enhancing the function of immune system. In previous studies, a polysaccharide fraction S-3 was screened from SJZD by assessment of immune system regulation, intestinal microbiota, and SCFA in order to explore the immune active ingredients in SJZD. In the present study, S-3 was further purified, and a homogeneous polysaccharide S-3-1 with a molecular mass of 13.5 × 104 Da was obtained after further fractionation by Sephadex G-150 size-exclusion chromatography. The immunological activities of S-3-1 were assayed in vitro for the first time. The determination of the anticomplement activity showed that S-3-1 displayed inhibitory effects on classical pathway of the complement system, with CH50 values of 530 μg/mL. The FT-IR analysis showed that S-3-1 had absorptive peaks characteristic of polysaccharides. The methylation and GC-MS analysis showed that it is comprised of Rha, Ara, Xyl, Man, Gal, and Glc in a relative molar ratio of 0.35 : 0.37 : 1.4 : 0.31 : 3 : 0.8 and that it mainly contained 1,4-linked-Glc and 1,6-linked-Gal glycosidic bonds. The morphology of S-3-1 was observed by atomic force microscope (AFM). These results provided evidences for tracking the material basis of SJZD immune activity
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