536 research outputs found
Frequency Detection and Change Point Estimation for Time Series of Complex Oscillation
We consider detecting the evolutionary oscillatory pattern of a signal when
it is contaminated by non-stationary noises with complexly time-varying data
generating mechanism. A high-dimensional dense progressive periodogram test is
proposed to accurately detect all oscillatory frequencies. A further
phase-adjusted local change point detection algorithm is applied in the
frequency domain to detect the locations at which the oscillatory pattern
changes. Our method is shown to be able to detect all oscillatory frequencies
and the corresponding change points within an accurate range with a prescribed
probability asymptotically. This study is motivated by oscillatory frequency
estimation and change point detection problems encountered in physiological
time series analysis. An application to spindle detection and estimation in
sleep EEG data is used to illustrate the usefulness of the proposed
methodology. A Gaussian approximation scheme and an overlapping-block
multiplier bootstrap methodology for sums of complex-valued high dimensional
non-stationary time series without variance lower bounds are established, which
could be of independent interest
Propagation of lump-type waves in nonlinear shallow water wave
In this work, a new extended shallow water wave equation in (3+1) dimensions was studied, which represents abundant physical meaning in a nonlinear shallow water wave. We discussed the interaction between a lump wave and a single solitary wave, which is an inelastic collision. Further, the interaction between a lump wave and two solitary waves and the interaction between a lump wave and a periodic wave was also studied using the Hirota bilinear method. Finally, the interaction among lump, periodic and one solitary wave was investigated. The dynamic properties of the obtained results are shown and analyzed by some three-dimensional images
Coupling of light from an optical fiber taper into silver nanowires
We report the coupling of photons from an optical fiber taper to surface
plasmon modes of silver nanowires. The launch of propagating plasmons can be
realized not only at ends of the nanowires, but also at the midsection. The
degree of the coupling can be controlled by adjusting the light polarization.
In addition, we present the coupling of light into multiple nanowires from a
single optical fiber taper simultaneously. Our demonstration offers a novel
method for optimizing plasmon coupling into nanoscale metallic waveguides and
promotes the realization of highly integrated plasmonic devices.Comment: 5 pages, 4 figure
Increased endothelin-1 in the rabbit model of middle cerebral artery occlusion
Endothelin-mediated vasoconstriction may theoretically aggravate ischemic neuronal damage. Although investigators have demonstrated that endothelins are produced by cerebral microvessel endothelial cells, astrocytes and neurons in vitro, whether endothelins are produced during cerebral ischemia is still unclear. The purpose of this study, therefore, was to measure endothelin-1 in brain tissue and plasma following middle cerebral artery occlusion and to examine the relationship between brain tissue and plasma endothelin-1 levels. The middle cerebral artery of rabbits was occluded for 2, 4 or 24 h. The amount of endothelin-1 in both brain tissue and plasma was determined by RIA. The results demonstrate that the concentrations of endothelin-1 in the ischemic brain tissue and plasma are both significantly increased after focal cerebral ischemia (P < 0.01). The data confirm that an acute and marked increase of endothelin-1 in brain tissue and plasma is associated with focal ischemic events. The possibility that endothelin-1 has a role in neuronal cell damage following focal ischemia warrants further attention.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31509/1/0000431.pd
FGF21 ameliorates the neurocontrol of blood pressure in the high fructose-drinking rats
Fibroblast growth factor-21 (FGF21) is closely related to various metabolic and cardiovascular disorders. However, the direct targets and mechanisms linking FGF21 to blood pressure control and hypertension are still elusive. Here we demonstrated a novel regulatory function of FGF21 in the baroreflex afferent pathway (the nucleus tractus solitarii, NTS; nodose ganglion, NG). As the critical co-receptor of FGF21, β-klotho (klb) significantly expressed on the NTS and NG. Furthermore, we evaluated the beneficial effects of chronic intraperitoneal infusion of recombinant human FGF21 (rhFGF21) on the dysregulated systolic blood pressure, cardiac parameters, baroreflex sensitivity (BRS) and hyperinsulinemia in the high fructose-drinking (HFD) rats. The BRS up-regulation is associated with Akt-eNOS-NO signaling activation in the NTS and NG induced by acute intravenous rhFGF21 administration in HFD and control rats. Moreover, the expressions of FGF21 receptors were aberrantly down-regulated in HFD rats. In addition, the up-regulated peroxisome proliferator-activated receptor-γ and -α (PPAR-γ/-α) in the NTS and NG in HFD rats were markedly reversed by chronic rhFGF21 infusion. Our study extends the work of the FGF21 actions on the neurocontrol of blood pressure regulations through baroreflex afferent pathway in HFD rats
The hornwort genome and early land plant evolution
Hornworts, liverworts and mosses are three early diverging clades of land plants, and together comprise the bryophytes. Here, we report the draft genome sequence of the hornwort Anthoceros angustus. Phylogenomic inferences confirm the monophyly of bryophytes, with hornworts sister to liverworts and mosses. The simple morphology of hornworts correlates with low genetic redundancy in plant body plan, while the basic transcriptional regulation toolkit for plant development has already been established in this early land plant lineage. Although the Anthoceros genome is small and characterized by minimal redundancy, expansions are observed in gene families related to RNA editing, UV protection and desiccation tolerance. The genome of A. angustus bears the signatures of horizontally transferred genes from bacteria and fungi, in particular of genes operating in stress-response and metabolic pathways. Our study provides insight into the unique features of hornworts and their molecular adaptations to live on land
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A regulatory mutant on TRIM26 conferring the risk of nasopharyngeal carcinoma by inducing low immune response.
The major histocompatibility complex (MHC) is most closely associated with nasopharyngeal carcinoma (NPC), but the complexity of its genome structure has proven challenging for the discovery of causal MHC loci or genes. We conducted a targeted MHC sequencing in 40 Cantonese NPC patients followed by a two-stage replication in 1065 NPC cases and 2137 controls of Southern Chinese descendent. Quantitative RT-PCR analysis (qRT-PCR) was used to detect gene expression status in 108 NPC and 43 noncancerous nasopharyngeal (NP) samples. Luciferase reporter assay and chromatin immunoprecipitation (ChIP) were used to assess the transcription factor binding site. We discovered that a novel SNP rs117565607_A at TRIM26 displayed the strongest association (OR = 1.909, Pcombined = 2.750 × 10-19 ). We also observed that TRIM26 was significantly downregulated in NPC tissue samples with genotype AA/AT than TT. Immunohistochemistry (IHC) test also found the TRIM26 protein expression in NPC tissue samples with the genotype AA/AT was lower than TT. According to computational prediction, rs117565607 locus was a binding site for the transcription factor Yin Yang 1 (YY1). We observed that the luciferase activity of YY1 which is binding to the A allele of rs117565607 was suppressed. ChIP data showed that YY1 was binding with T not A allele. Significance analysis of microarray suggested that TRIM26 downregulation was related to low immune response in NPC. We have identified a novel gene TRIM26 and a novel SNP rs117565607_A associated with NPC risk by regulating transcriptional process and established a new functional link between TRIM26 downregulation and low immune response in NPC
Control of Cotton Fibre Elongation by a Homeodomain Transcription Factor GhHOX3
Cotton fibres are unusually long, single-celled epidermal seed trichomes and a model for plant cell growth, but little is known about the regulation of fibre cell elongation. Here we report that a homeodomain-leucine zipper (HD-ZIP) transcription factor, GhHOX3, controls cotton fibre elongation. GhHOX3 genes are localized to the 12th homoeologous chromosome set of allotetraploid cotton cultivars, associated with quantitative trait loci (QTLs) for fibre length. Silencing of GhHOX3 greatly reduces (\u3e80%) fibre length, whereas its overexpression leads to longer fibre. Combined transcriptomic and biochemical analyses identify target genes of GhHOX3 that also contain the L1-box cis-element, including two cell wall loosening protein genes GhRDL1 and GhEXPA1. GhHOX3 interacts with GhHD1, another homeodomain protein, resulting in enhanced transcriptional activity, and with cotton DELLA, GhSLR1, repressor of the growth hormone gibberellin (GA). GhSLR1 interferes with the GhHOX3–GhHD1 interaction and represses target gene transcription. Our results uncover a novel mechanism whereby a homeodomain protein transduces GA signal to promote fibre cell elongation
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