106,064 research outputs found
K-theory for group C*-algebras
No full textThese notes are based on a lecture course given by the first author in the Sedano Winter School on K-theory held in Sedano, Spain, on January 22-27th of 2007. They aim at introducing K-theory of C*-algebras, equivariant K-homology and KK-theory in the context of the Baum-Connes conjectur
Optimal generation of spatially coherent soft X-ray isolated attosecond pulses in a gas-filled waveguide using two-color synthesized laser pulses
Full text linkCitation: Jin, C., Hong, K. H., & Lin, C. D. (2016). Optimal generation of spatially coherent soft X-ray isolated attosecond pulses in a gas-filled waveguide using two-color synthesized laser pulses. Scientific Reports, 6, 11. doi:10.1038/srep38165We numerically demonstrate the generation of intense, low-divergence soft X-ray isolated attosecond pulses in a gas-filled hollow waveguide using synthesized few-cycle two-color laser waveforms. The waveform is a superposition of a fundamental and its second harmonic optimized such that highest harmonic yields are emitted from each atom. We then optimize the gas pressure and the length and radius of the waveguide such that bright coherent high-order harmonics with angular divergence smaller than 1 mrad are generated, for photon energy from the extreme ultraviolet to soft X-rays. By selecting a proper spectral range enhanced isolated attosecond pulses are generated. We study how dynamic phase matching caused by the interplay among waveguide mode, neutral atomic dispersion, and plasma effect is achieved at the optimal macroscopic conditions, by performing time-frequency analysis and by analyzing the evolution of the driving laser's electric field during the propagation. Our results, when combined with the on-going push of high-repetition-rate lasers (sub- to few MHz's) may eventually lead to the generation of high-flux, low-divergence soft X-ray tabletop isolated attosecond pulses for applications
Constructing vertex-disjoint paths in (n,k)-star graphs
No full text[[abstract]]This work describes a novel routing algorithm for constructing a container of width n - 1 between a pair of vertices in an (n, k)-star graph with connectivity it - 1. Since Lin et al. [T.C. Lin, D.R. Duh, H.C. Cheng, Wide diameter of (n, k)-star networks, in: Proceedings of the International Conference on Computing, Communications and Control Technologies, vol. 5, 2004 pp. 160-165] already calculated the wide diameters in (n, n - 1)-star and (n, 1)-star graphs, this study only considers an (n, k)-star with 2 <= k <= n - 2. The length of the longest container among all constructed containers serves as the upper bound of the wide diameter of an (n, k)-star graph. The lower bound of the wide diameter of an (n, k)-star graph with 2 <= k <= [n/2] and the lower bound of the wide diameter of a regular graph with a connectivity of 2 or above are also computed. Measurement results indicate that the wide diameter of an (n, k)-star graph is its diameter plus 2 for 2 <= k <= [n/2], or its diameter plus a value between 1 and 2 for [n/2] + 1 <= k <= n - 2. (c) 2007 Elsevier Inc. All rights reserved.[[note]]SC
Rathalos treecko Lin & Zhao & Koh & Li 2022, comb. nov.
No full textRathalos treecko (Lin & Li, 2021) comb. nov. Anyphaena treecko Lin & Li, In: Lin et al., 2021: 101, figs 9A–C, 10A–B, 14I–J. Material examined. Holotype ♂ (IZCAS-Ar42404), China: Hainan, Changjiang County, Bawangling, Dongsizhan (19.0495°N, 109.1157°E), 23 April 2009, G. Tang leg. (examined). Paratypes. 2♀ (IZCAS-Ar42405–Ar42406), same data as holotype (examined). Diagnosis. See Lin et al. (2021). Description. See Lin et al. (2021). Distribution. China (Hainan). Comments. The cymbial apophysis, the triangular epigyne and the straight copulatory duct indicate that this species belongs to Rathalos Lin & Li, gen. nov. Thus, we transfer it from Anyphaena to Rathalos Lin & Li, gen. nov.Published as part of Lin, Yejie, Zhao, Huifeng, Koh, Joseph K H & Li, Shuqiang, 2022, Taxonomy notes on twenty-eight spider species (Arachnida: Araneae) from Asia, pp. 198-270 in Zoological Systematics 47 (3) on page 201, DOI: 10.11865/zs.2022303, http://zenodo.org/record/717585
Identification of cis-regulatory elements from the C. elegans Hox gene lin-39 required for embryonic expression and for regulation by the transcription factors LIN-1, LIN-31 and LIN-39
No full textExpression of the Caenorhabditis elegans Hox gene lin-39 begins in the embryo and continues in multiple larval cells, including the P cell lineages that generate ventral cord neurons (VCNs) and vulval precursor cells (VPCs). lin-39 is regulated by several factors and by Wnt and Ras signaling pathways; however, no cis-acting sites mediating lin-39 regulation have been identified. Here, we describe three elements controlling lin-39 expression: a 338-bp upstream fragment that directs embryonic expression in P5-P8 and their descendants in the larva, a 247-bp intronic region sufficient for VCN expression, and a 1.3-kb upstream cis-regulatory module that drives expression in the VPC P6.p in a Ras-dependent manner. Three trans-acting factors regulate expression via the 1.3-kb element. A single binding site for the ETS factor LIN-1 mediates repression in VPCs other than P6.p; however, loss of LIN-1 decreases expression in P6.p. Therefore, LIN-1 acts both negatively and positively on lin-39 in different VPCs. The Forkhead domain protein LIN-31 also acts positively on lin-39 in P6.p via this module. Finally, LIN-39 itself binds to this element, suggesting that LIN-39 autoregulates its expression in P6.p. Therefore, we have begun to unravel the cis-acting sites regulating lin-39 Hox gene expression and have shown that lin-39 is a direct target of the Ras pathway acting via LIN-1 and LIN-31..SC: 0S; 7B; 0T; CA; PE; EC; SO; AA; XURL: URL; E-MAIL; DOI; DIGITAL-OBJECT-IDENTIFIERSource type: Electronic(1)[email protected]; http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WDG-4K0C9JV-3&_user=10&_coverDate=09%2F15%2F2006&_rdoc=21&_fmt=summary&_orig=browse&_srch=doc-info(%23toc%236766%232006%23997029997%23633147%23FLA%23display%23Volume)&_cdi=6766&_sort=d&_docanchor=&view=c&_ct=24&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=3e6063983fd5b459eac74b274375875e; http://upei-resolver.asin-risa.ca?sid=SP:CABI&id=pmid:&id=doi%3a10.1016%2fj.ydbio.2006.05.008&issn=0012-1606&isbn=&volume=297&issue=2&spage=550&pages=550-565&date=2006&title=Developmental%20Biology&atitle=Identification%20of%20cis-regulatory%20elements%20from%20the%20C.%20elegans%20Hox%20gene%20lin-39%20required%20for%20embryonic%20expression%20and%20for%20regulation%20by%20the%20transcription%20factors%20LIN-1%2c%20LIN-31%20and%20LIN-39.&aulast=Wagmaister&pid=%3Cauthor%3EWagmaister%2c%20J%20A%3bMiley%2c%20G%20R%3bMorris%2c%20C%20A%3bGleason%2c%20J%20E%3bMiller%2c%20L%20M%3bKornfeld%2c%20K%3bEisenmann%2c%20D%20M%3C%2Fauthor%3E%3CAN%3E20073040429%3C%2FAN%3E%3CDT%3EJournal%20article%3C%2FDT%3
Differential roles of the microRNA let-7 in C. elegans tissue development
Full text linkThe organs and tissues of the human body comprise of an astonishing variety of cells as different in morphology and function as muscle cells and neurons. Amazingly, despite their different protein contents, they largely contain the identical genomic information. In order to understand the processes that enable this differentiation, we need to determine the underlying regulatory mechanisms. A very recent discovery in this context was the posttranscriptional regulation of gene expression by microRNAs (miRNAs). miRNAs are small RNA molecules that mediate translational repression and degradation of mRNA transcripts through partial complementarity to their 3’ untranslated region (UTR) . Among the first miRNAs to be identified, let-7 stands out for its high conservation in sequence and developmental functions in development throughout the animal kingdom. During my PhD, I studied the role of let-7 in Caenorhabditis elegans in the context of two distinct processes of tissue development, namely differentiation of the epidermis (called hypodermis), and morphogenesis of the vulva. The functions of the let-7 miRNA in formation of the adult cuticle have been extensively studied and are well understood. let-7 controls differentiation of specific, mitotically active epidermal cells by inducing cell cycle exit, fusion, and switch to an adult specific transcriptional program upon repression of targets such as lin-41, daf-12, hbl-1 and let-60/ras. I set out to identify novel interactors of let-7 in a genome-wide RNAi screen for suppression of the lethal let-7 bursting phenotype. Candidates were then verified using fluorescence-based reporter systems for onset of hypodermis differentiation and intensity of repression of a known target. Thereby, I was able to validate a whole set of novel members of the let-7 network, comprising genes downstream in the pathway as well as potential regulators of let-7 activity. Notably, both groups of repressors contain factors required for cell cycle progression and mitosis, which indicates an active crosstalk between let-7 and the cell-cycle machinery. In a second project, I explored the molecular basis for the prominent let-7 vulval bursting phenotype. Despite the absence of overproliferation or any other obvious phenotype in vulval morphogenesis, I was able to show that let-7 activity is required in the vulva, and that its major function in this context is repression of a single target, namely lin-41. Disruption of let-7 binding to lin-41 through modification of the let-7 complementary sites by CRISPR/Cas9 mediated genome editing suffices to trigger the bursting phenotype, proving that repression of a single target is the key function of the miRNA in this context. In summary, my work shows that while both differentiation of hypodermis as well as vulval integrity are mediated through repression of lin-41, the downstream effect of this regulation seem to differ, suggesting that let-7 can be wired to control distinct processes depending on the cellular context. With respect to the latest findings both in C. elegans as well as in mammals, it will be interesting to determine if this depends on differential molecular functions of LIN-41 in the two tissues
Spatial Chow-Lin Methods for Data Completion in Econometric Flow Models
Full text linkFlow data across regions can be modeled by spatial econometric models, see LeSage and Pace (2009). Recently, regional studies became interested in the aggregation and disaggregation of flow models, because trade data cannot be obtained at a disaggregated level but data are published on an aggregate level. Furthermore, missing data in disaggregated flow models occur quite often since detailed measurements are often not possible at all observation points in time and space. In this paper we develop classical and Bayesian methods to complete flow data. The Chow and Lin (1971) method was developed for completing disaggregated incomplete time series data. We will extend this method in a general framework to spatially correlated flow data using the cross-sectional Chow-Lin method of Polasek et al. (2009). The missing disaggregated data can be obtained either by feasible GLS prediction or by a Bayesian (posterior) predictive density.Missing values in spatial econometrics, MCMC, non-spatial Chow-Lin (CL) and spatial Chow-Lin (SCL) methods, spatial internal flow (SIF) models, origin and destination (OD) data
Figure 12. Cryptodrassus beijing Lin & Li in Taxonomy notes on twenty-eight spider species (Arachnida: Araneae) from Asia
No full textFigure 12. Cryptodrassus beijing Lin & Li, sp. nov., holotype male, left palp. A. Prolateral view; B. Ventral view; C. Retrolateral view. Arrows show apophyses. Abbreviations: C—conductor; E—embolus; SD—sperm duct; ST—subtegulum. Scale bars = 0.1 mm.Published as part of Lin, Yejie, Zhao, Huifeng, Koh, Joseph K H & Li, Shuqiang, 2022, Taxonomy notes on twenty-eight spider species (Arachnida: Araneae) from Asia, pp. 198-270 in Zoological Systematics 47 (3) on page 215, DOI: 10.11865/zs.2022303, http://zenodo.org/record/717585
Figure 14. Cryptodrassus beijing Lin & Li in Taxonomy notes on twenty-eight spider species (Arachnida: Araneae) from Asia
No full textFigure 14. Cryptodrassus beijing Lin & Li, sp. nov., paratypes male (A–B) and female (C–D). A, C. Habitus, dorsal view; B, D. Same, lateral view. Scale bars = 0.5 mm.Published as part of Lin, Yejie, Zhao, Huifeng, Koh, Joseph K H & Li, Shuqiang, 2022, Taxonomy notes on twenty-eight spider species (Arachnida: Araneae) from Asia, pp. 198-270 in Zoological Systematics 47 (3) on page 217, DOI: 10.11865/zs.2022303, http://zenodo.org/record/717585
Figure 52. Dolichognatha yue Lin & Li in Taxonomy notes on twenty-eight spider species (Arachnida: Araneae) from Asia
No full textFigure 52. Dolichognatha yue Lin & Li, sp. nov., holotype male, left palp. A. Prolateral view; B. Ventral view; C. Retrolateral view. Abbreviations: C—conductor; CEBP—ectobasal cymbial process; E—embolus; P—paracymbium; SD—sperm duct. Scale bars = 0.1 mm.Published as part of Lin, Yejie, Zhao, Huifeng, Koh, Joseph K H & Li, Shuqiang, 2022, Taxonomy notes on twenty-eight spider species (Arachnida: Araneae) from Asia, pp. 198-270 in Zoological Systematics 47 (3) on page 257, DOI: 10.11865/zs.2022303, http://zenodo.org/record/717585
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