798 research outputs found
Individuals’ leukocyte DNA double-strand break repair as an indicator of radiosurgery responses for cerebral arteriovenous malformations.
No full textBeyond Lesson Studies and Design Experiments: Using theoretical tools in practice and finding out how they work
Full text linkThis paper aims to illustrate how fruitful insights into the link between school teaching practice and student learning outcomes can be theoretically grounded by the variation theory from the field of phenomenography; and from this framework demonstrate how a 'pedagogy of awareness' can be implemented in the classroom. In this study, five teachers and 162 students at Primary Four level of school education in Hong Kong participated and the practice of the 'learning study' was adopted. By comparing the results of pre- and posttests, a significant gain was observed in the students learning outcomes.
Phenotypic traits of the Mediterranean Phragmites australis M1 lineage : differences between the native and introduced ranges
No full textThe environmental conditions in the new ranges of introduced plant species are often different from the conditions in their native ranges, and invasive plant species have been assumed to adapt to different environmental conditions by rapid ecological evolution in the invasive range after the introduction. Another interpretation of the change in plant traits after their introduction, however, is ecological fitting, which is based on the inherently high phenotypic plasticity of the species rather than on evolution. The Mediterranean haplotype M1 lineage of the wetland grass Phragmites australis was introduced to the coastal wetlands along the Gulf Coast of North America, where it is exposed to a different climate compared to its original range. The climate in the native range is arid or temperate with dry and hot summers, whereas the climate in the introduced range is warmer and has a higher and more uniform precipitation than that in the native range. This warmer and more humid environment is likely to pose different selection pressures to the plants in the introduced range and thus cause rapid evolutionary change and phenotypic differentiation in the introduced range. Here, we compared phenotypic traits of the M1 lineage from the native and introduced ranges in a common garden experiment to study the processes assisting the successful spread in the introduced range. Overall, the native and introduced groups were similar, but we detected a few phenotypic traits that diverged. Ecological fitting could be the fundamental mechanism by which the P. australis M1 lineage survives and spreads in the introduced Gulf Coast region. However, further research is needed to assess how the diverging traits observed in our study in Denmark (lower photosynthetic rates, lower chlorophylls concentration and higher leaf K concentration for the introduced than for the native genotypes) are expressed in the two ranges
Invasion of old world phragmites australis in the new world : Precipitation and temperature patterns combined with human influences redesign the invasive niche
No full textAfter its introduction into North America, Euro-Asian Phragmites australis became an aggressive invasive wetland grass along the Atlantic coast of North America. Its distribution range has since expanded to the middle, south and southwest of North America, where invasive P. australis has replaced millions of hectares of native plants in inland and tidal wetlands. Another P. australis invasion from the Mediterranean region is simultaneously occurring in the Gulf region of the United States and some countries in South America. Here, we analysed the occurrence records of the two Old World invasive lineages of P. australis (Haplotype M and Med) in both their native and introduced ranges using environmental niche models (ENMs) to assess (i) whether a niche shift accompanied the invasions in the New World; (ii) the role of biologically relevant climatic variables and human influence in the process of invasion; and (iii) the current potential distribution of these two lineages. We detected local niche shifts along the East Coast of North America and the Gulf Coast of the United States for Haplotype M and around the Mississippi Delta and Florida of the United States for Med. The new niche of the introduced Haplotype M accounts for temperature fluctuations and increased precipitation. The introduced Med lineage has enlarged its original subtropical niche to the tropics-subtropics, invading regions with a high annual mean temperature (> ca. 10 °C) and high precipitation in the driest period. Human influence is an important factor for both niches. We suggest that an increase in precipitation in the 20th century, global warming and human-made habitats have shaped the invasive niches of the two lineages in the New World. However, as the invasions are ongoing and human and natural disturbances occur concomitantly, the future distribution ranges of the two lineages may diverge from the potential distribution ranges detected in this study
Living in two worlds : Evolutionary mechanisms act differently in the native and introduced ranges of an invasive plant
Full text linkIdentifying the factors that influence spatial genetic structure among populations can provide insights into the evolution of invasive plants. In this study, we used the common reed (Phragmites australis), a grass native in Europe and invading North America, to examine the relative importance of geographic, environmental (represented by climate here), and human effects on population genetic structure and its changes during invasion. We collected samples of P. australis from both the invaded North American and native European ranges and used molecular markers to investigate the population genetic structure within and between ranges. We used path analysis to identify the contributions of each of the three factors—geographic, environmental, and human-related—to the formation of spatial genetic patterns. Genetic differentiation was observed between the introduced and native populations, and their genetic structure in the native and introduced ranges was different. There were strong effects of geography and environment on the genetic structure of populations in the native range, but the human-related factors manifested through colonization of anthropogenic habitats in the introduced range counteracted the effects of environment. The between-range genetic differences among populations were mainly explained by the heterogeneous environment between the ranges, with the coefficient 2.6 times higher for the environment than that explained by the geographic distance. Human activities were the primary contributor to the genetic structure of the introduced populations. The significant environmental divergence between ranges and the strong contribution of human activities to the genetic structure in the introduced range suggest that invasive populations of P. australis have evolved to adapt to a different climate and to human-made habitats in North America
Phylogenetic diversity shapes salt tolerance in Phragmites australis estuarine populations in East China
Full text linkEstuaries are dynamic and selective environments that provide frequent opportunities for the turnover of Phragmites australis populations. We studied Phragmites genetic diversity patterns in three of the major deltas of China, viz. the Yellow River, the Yangtze and the Liaohe, in relation to Phragmites global phylogeography and soil salinity. We found that two distantly related P. australis haplotypes, each with intercontinental distribution, co-occur in these deltas in China. One is European Phragmites (Haplotype O) and is related to P. japonicus; the other (Haplotype P) has its range in East Asia and Australia and is related to the Asian tropical species P. karka. The two haplotypes have differing salt tolerance, with Haplotype O in areas with the highest salinity and Haplotype P in areas with the lowest. Introgressed hybrids of Haplotype P with P. karka, and F1 hybrids with Haplotype O, have higher salt tolerance than Haplotype P. Phylogenetic diversity appears as the factor that better explains population structure and salinity tolerance in these estuaries. Future research may explain whether the two P. australis haplotypes evolved in East Asia, and East Asia is a center of Phragmites diversity, or are introduced and a threat to P. japonicus and P. karka
Radio transceiver architectures and design issues for wideband cellular systems
No full textAs the era of content driven and rich multimedia mobile applications evolves, the need arises for efficient wideband cellular systems. This paper presents modern radio transceiver architectures used in 3G cellular handsets, such as EDGE, cdma2000, and WCDMA-HSDPA. This includes future ΣΔ-ADC based receiver and mostly all-digital transmitter architectures, which are being enabled by the current aggressive scaling of CMOS technology and the push toward full radio systcm-on-chip (SoC) integration. Furthermore, the paper focuses on discussing some key RF system design issues, and their influence on the choice of architecture used for a specific cellular radio-chipset solution.Elliott MR, 2004, IEEE J SOLID-ST CIRC, V39, P2190, DOI 10.1109-JSSC.2004.836340; KACSMAN D, IEEE RFIC S 2005, P281; MUNKER C, IEEE RFIC S 2005, P265; Neuvo Y., 2004, IEEE INT SOL STAT CI, P32; *QUALC INC, 2001, EC WIR MOB DAT; Razavi B, 1997, IEEE T CIRCUITS-II, V44, P428, DOI 10.1109-82.592569; SCHELL S, 2000, TROP INC PRES FEB 22; Sowlati T, 2004, IEEE J SOLID-ST CIRC, V39, P2179, DOI 10.1109-JSSC.2004.836335; TAMURA M, IEEE RFIC S 2005, P269; van Veldhoven RHM, 2003, IEEE J SOLID-ST CIRC, V38, P2069, DOI 10.1109-JSSC.2003.819165; Waite H, 2004, IEEE J SOLID-ST CIRC, V39, P1175, DOI 10.1109-JSSC.2004.829965; ZHOU J, IEEE RFIC S 2005, P1710
A CeO <sub>2</sub> (100) surface reconstruction unveiled by in situ STEM and particle swarm optimization techniques
Full text linkThe reconstruction of the polar CeO
(100) surface has been a subject of long-standing debates due to its complexity and the limited availability of experimental data. Herein, we successfully reveal a CeO
(100)–(4 × 6) surface reconstruction by combining in situ spherical aberration–corrected scanning transmission electron microscopy, density functional theory calculations, and a particle swarm optimization–based algorithm for structure searching. We have further elucidated the stabilizing mechanism of the reconstructed structure, which involves the splitting of the filled Ce(4f) states and the mixing of the lower-lying ones with the O(2p) orbitals, as evidenced by the projected density of states. We also reveal that the surface chemisorption properties toward water molecules, an important step in numerous heterogeneous catalytic reactions, are enhanced. These insights into the distinct properties of ceria surface pave the way for performance improvements of ceria in a wide range of applications..W. acknowledges the financial support of the national natural Science Foundationof china (51971202, 52025011, and 92045301), the Key Research and development Programof Zhejiang Province (2021c01003), the Zhejiang Provincial natural Science Foundation ofchina (ld19B030001), the Shanxi- Zheda institute of Advanced Materials and chemicalengineering, and the Fundamental Research Funds for the central Universities. W.Y.acknowledges the financial support of the national natural Science Foundation of china(52171019), the Zhejiang Provincial natural Science Foundation of china (lR23B030004), andthe national Key Research and development Program (2022YFA1505500). Z.-K.h.acknowledges the financial support of the national nature Science Foundation of china(22302173). M.v.G.-P. thanks the support of the Grant Pid2021-128915nB- i00 funded by Mcin/Aei/10.13039/501100011033 and by “eRdF A way of making europe.” Author contributions:conceptualization: S.l., Z.-K.h., W.Y.., h.Y., M.v.G.-P., and Y.W. Methodology: K.Z., G.l., S.l.,Z.- K.h., W.Y., and Y.W. investigation: K.Z., G.l., c.Z., S.c., and h.Y. visualization: K.Z., G.l., Z.-K.h.,Y.J., h.Y., and Y.W. Supervision: S.l., Z.-K.h., W.Y., h.Y., M.v.G.-P., and Y.W. Writing—original draft:K.Z. and Y.W. Writing—review and editing: K.Z., G.l., S.d.l., Z.- K.h., Y.J., W.Y., h.Y., M.v.G.- P., andY.W. Funding acquisition: Z.-K.h., W.Y., and Y.W. data curation: W.Y. validation: G.l., S.l., W.Y.,h.Y., and Y.W. Project administration: Z.-K.h., W.Y., and Y.W. Formal analysis: K.Z., G.l., S.l.,Z.- K.h., h.Y. Resources: S.l. and Y.W. Software: S.l
Symbolic Analysis for Boundary Problems: From Rewriting to Parametrized Groebner Bases
Full text linkWe review our algebraic framework for linear boundary problems (concentrating on ordinary differential equations). Its starting point is an appropriate algebraization of the domain of functions, which we have named integro-differential algebras. The algebraic treatment of boundary problems brings up two new algebraic structures whose symbolic representation and computational realization is based on canonical forms in certain commutative and noncommutative polynomial domains. The first of these, the ring of integro-differential operators, is used for both stating and solving linear boundary problems. The other structure, called integro-differential polynomials, is the key tool for describing extensions of integrodifferential algebras. We use the canonical simplifier for integro-differential polynomials for generating an automated proof establishing a canonical simplifier for integro-differential operators. Our approach is fully implemented in the THEOREMA system; some code fragments and sample computations are included
Diabetes promotes an inflammatory macrophage phenotype and atherosclerosis through acyl-CoA synthetase 1
Full text linkAuthor contributions: J.E.K., L.B., C.N.S., and K.E.B. designed research; J.E.K., F.K., S.B., M.M.A., A.V.-G., T.V., L.O.L., L.B., K.R.B., and S.P.-P. performed research; W.Y., A.C., S.S., T.N.W., J.W.H., and R.A.C. contributed new reagents/analytic tools; J.E.K., L.B., S.S., S.P., and K.E.B. analyzed data; and J.E.K. and K.E.B. wrote the paper
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