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Strands
Kinds of Strands Terms modified by Strands Selected AbstractsSTRANDS: Interactive Simulation of Thin Solids using Cosserat ModelsCOMPUTER GRAPHICS FORUM, Issue 3 2002Dinesh K. Pai Strandsare thin elastic solids that are visually well approximated as smooth curves, and yet possess essential physical behaviors characteristic of solid objects such as twisting. Common examples in computer graphics include: sutures, catheters, and tendons in surgical simulation; hairs, ropes, and vegetation in animation. Physical models based on spring meshes or 3D finite elements for such thin solids are either inaccurate or inefficient for interactive simulation. In this paper we show that models based on the Cosserat theory of elastic rods are very well suited for interactive simulation of these objects. The physical model reduces to a system of spatial ordinary differential equations that can be solved efficiently for typical boundary conditions. The model handles the important geometric non-linearity due to large changes in shape. We introduce Cosserat-type physical models, describe efficient numerical methods for interactive simulation of these models, and implementation results. [source] Aeolian fetch distance and secondary airflow effects: the influence of micro-scale variables on meso-scale foredune developmentEARTH SURFACE PROCESSES AND LANDFORMS, Issue 7 2008Kevin Lynch Abstract Unsuccessful attempts to use process-scale models to predict long-term aeolian sediment transport patterns have long been a feature of aeolian research. It has been proposed that one approach to overcome these problems is to identify micro-scale variables that are important at longer timescales. This paper assesses the contribution of two system variables (secondary airflow patterns and fetch distance) to medium-term (months to years) dune development. The micro-scale importance of these variables had been established during previous work at the site (Magilligan Strand, Northern Ireland). Three methods were employed. First, sand drift potentials were calculated using 2 years of regional wind data and a sediment transport model. Second, wind data and large trench traps (2 m length × 1 m width × 1·5 m depth) were used to assess the actual sediment transport patterns over a 2-month period. Third, a remote-sensing technique for the identification of fetch distance, a saltation impact sensor (Safire) and wind data were utilized to gauge, qualitatively, sediment transport patterns over a 1-month period. Secondary airflow effects were found to play a major role in the sediment flux patterns at these timescales, with measured and predicted rates matching closely during the trench trap study. The results suggest that fetch distance is an unimportant variable at this site. Copyright © 2007 John Wiley & Sons, Ltd. [source] Species richness and parasitism in an assemblage of parasitoids attacking maize stem borers in coastal KenyaECOLOGICAL ENTOMOLOGY, Issue 1 2003Guofa Zhou Abstract. 1. Parasitoids were reared from four species of lepidopteran stem borer collected in maize in southern coastal Kenya from 1992 to 1999. The stem borers included three native species, Sesamia calamistis Hampson, Busseola fusca Fuller, and Chilo orichalcociliellus (Strand), and one exotic borer, Chilo partellus (Swinhoe). A total of 174 663 caterpillars was collected, of which 12 645 were parasitised. 2. Twenty-six primary parasitoid species were reared from the exotic borer, C. partellus, indicating a rapid accumulation of native parasitoids on the alien borer. 3. The three most abundant parasitoids were the larval parasitoids Cotesia sesamiae Cameron, Cotesia flavipes (Cameron), and the pupal parasitoid Pediobius furvus Gahan. The pupal parasitoid Dentichasmias busseolae Heinrich and the larval parasitoid Goniozus indicus Ashmead were also common. All used an ingress-and-sting method of attack. 4. Cotesia flavipes, introduced into Kenya in 1993, was found in all seasons from 1997 onwards, and has become the most abundant stem borer larval parasitoid in the area. A native congener, Cotesia sesamiae, appeared in all seasons from 1992 to 1999. Together, these two parasitoids accounted for 83.3% of the parasitised borers. 5. Thirty parasitoid species were recovered in Kilifi district, 27 in Kwale, and 15 in Taita Taveta. Parasitism was much greater in Taita Taveta district than in Kilifi or Kwale districts. [source] Tongbian: A Chinese Strand of ThoughtJOURNAL OF CHINESE PHILOSOPHY, Issue 4 2000Chenshan Tian [source] Strong genetic influence on IPN vaccination-and-challenge trials in Atlantic salmon, Salmo salar L.JOURNAL OF FISH DISEASES, Issue 8 2008A Ramstad Abstract Two series of experimental challenge trials were performed for evaluation of multivalent oil-adjuvanted vaccines with and without an infectious pancreatic necrosis virus (IPNV) antigen component. In both the trial series, Atlantic salmon were hatched, reared, vaccinated and subjected to temperature and light manipulation to induce smoltification. When ready for sea the fish were transported to the VESO Vikan experimental laboratory for bath or cohabitant challenge with IPNV. In the first series, four vaccination and bath challenge trials involving 2-year classes of experimental fish were conducted. In the second series, three groups of eyed eggs of Atlantic salmon allegedly differing in their innate resistance to IPNV were used (Storset, Strand, Wetten, Kjøglum & Ramstad 2007). Hatching, rearing and smoltification were synchronized for each group, and fish from each genetic group were randomly allocated IPN vaccine, reference vaccine or saline before being placed into parallel tanks for bath or cohabitant challenge. In the first series of trials, IPN-specific mortality commenced on day 10,12 after bath challenge. Replicates showed similar results. In trials 1 and 2 belonging to the same experimental fish year class, the average cumulative control mortality reached 60.6% and 79.5%, respectively, whereas in trials 3 and 4 belonging to the following year class the control mortality was consistently below 50%. In the second series of trials, the experimental fish originating from allegedly IPN susceptible parents consistently showed the highest cumulative mortality among the unvaccinated controls (>75%) whereas smolts derived from allegedly IPNV resistant parents showed only 26,35% control mortality. The IPN-vaccinated fish experienced significantly improved survival vs. the fish immunized with reference vaccine, with RPS values above 75% in the IPN susceptible strain. In the IPN resistant strain, the protection outcomes were variable and in part non-significant. The outcome of both the trial series suggests that control mortalities above 50% are necessary to reliably demonstrate specific protection with IPN vaccines. [source] Race, Power, and Equity in a Multiethnic Urban Elementary School with a Dual-Language "Strand" ProgramANTHROPOLOGY & EDUCATION QUARTERLY, Issue 1 2010Deborah Palmer Dual-language education is often lauded for providing high-caliber bilingual instruction in an integrated classroom. This is complicated, however, when a dual-language program does not include all members of a school community. This article examines a "strand" dual-language program that attracts middle-class white students to a predominantly black and Latino community; yet, only some Latino students and almost no black students are included in the dual-language program. Although rarely directly discussing race, teachers and parents simultaneously commend the program for bringing diversity and enrichment to the campus, and accuse it of exacerbating inequities in the educational experiences of different children at the school. Taking a critical race perspective, and in particular using the principle of "interest convergence" and the frames of "color-blind racism" (Eduardo Bonilla-Silva 2006), this article works to uncover the forces underlying these tensions.,[two-way immersion, dual-language education, African Americans, critical race theory] [source] The Folding and Unfolding Kinetics of the i-Motif Structure Formed by the C-Rich Strand of Human Telomere DNACHEMBIOCHEM, Issue 11 2005Yong Zhao Dr. Return to the fold. Nucleic acids with four tandem cytidine-rich repeats can fold into a structure called the i-motif at acidic pH. The folding- and unfolding-rate constants of such a sequence in vertebrate telomere DNA were measured. Protons were found to promote i-motif formation by increasing the folding and decreasing the unfolding. [source] Evolution of a Constitutional Dynamic Library Driven by Self-Organisation of a Helically Folded Molecular StrandCHEMISTRY - A EUROPEAN JOURNAL, Issue 16 2010Lisa Lao Dr., Luciana Abstract Conversion of macrocyclic imine entities into helical strands was achieved through three- and four-component exchange reactions within constitutionally dynamic libraries. The generation of sequences of the intrinsic helicity codon, based on the hydrazone,pyrimidine fragment obtained by condensation of pyrimidine dialdehyde A with pyrimidine bis-hydrazine B, shifted the equilibrium between all the possible macrocycles and strands towards the full expression (>98%) of helical product [A/B]. Furthermore, it was shown that chain folding accelerated the dynamic exchange reactions among the library members. Lastly, in four-component experiments (involving A, B, E and either C or D), even though the macrocyclic entities ([A/C], [B/E]; [A/D], [B/E]) were the kinetically preferred products, over time dialdehyde A relinquished its initial diamine partners C or D to opt for bis-hydrazine B, which allowed the preferential formation of the helically folded strand. The present results indicate that self-organisation pressure was able to drive the dynamic system towards the selective generation of the strand undergoing helical folding. [source] Development of lymphatic vessels in mouse embryonic and early postnatal heartsDEVELOPMENTAL DYNAMICS, Issue 10 2008Juszy, Micha Abstract We aimed to study the spatiotemporal pattern of lymphatic system formation in the embryonic and early postnatal mouse hearts. The first sign of the development of lymphatics are Lyve-1,positive cells located on the subepicardial area. Strands of Lyve-1,positive cells occur first along the atrioventricular sulcus of the diaphragmatic surface and then along the great arteries. Lumenized tubules appear, arranged in rows or in a lattice. They are more conspicuous in dorsal atrioventricular junction, along the major venous and coronary artery branches and at the base of the aorta and the pulmonary trunk extending toward the heart apex. At later stages, some segments of the lymphatic vessels are partially surrounded by smooth muscle cells. Possible mechanisms of lymphangiogenesis are: addition of Lyve-1,positive cells to the existing tubules, elongation of the lymphatic lattice, sprouting and coalescence of tubules. We discuss the existence of various subpopulations of endothelial cells among the Lyve-1,positive cells. Developmental Dynamics 237:2973,2986, 2008. © 2008 Wiley-Liss, Inc. [source] Cyclic tests of post-tensioned precast CFT segmental bridge columns with unbonded strandsEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 2 2006Chung-Che Chou Abstract Two ungrouted post-tensioned, precast concrete-filled tube (CFT) segmental bridge columns were tested under lateral cyclic loading to evaluate the seismic performance of the column details. The specimens included a load stub, four equal-height circular CFT segments, and a footing. Strands were placed through the column and post-tensioned to provide a precompression of the column against the footing. One specimen also contained energy-dissipating devices at the base to increase the hysteretic energy. The test results showed that (1) both specimens could develop the maximum flexural strength at the design drift and achieve 6% drift with small strength degradation and residual displacement, (2) the proposed energy-dissipating device could increase energy dissipation in the hysteresis loops, and (3) the CFT segmental columns rotated not only about the base but also about the interface above the bottom segment. This study proposed and verified a method to estimate the experimental flexural displacement using two plastic hinges in the segmental column. Copyright © 2005 John Wiley & Sons, Ltd. [source] Oligonucleotide Duplexes with Tethered Photoreactive Ruthenium(II) Complexes: Influence of the Ligands and Their Linker on the Photoinduced Electron Transfer and Crosslinking Processes of the Two StrandsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 4 2009Stéphanie Deroo Abstract The photoreactivity of new RuII -oligonucleotide conjugates is investigated in the presence of their complementary strands. The goal is to determine the origins of different effects of parameters that control the photocrosslinking process of the two strands. Therefore, two RuII compounds, either [Ru(tap)3]2+or [Ru(tap)2phen]2+ (tap = 1,4,5,8-tetraazaphenanthrene, phen = 1,10-phenanthroline) with different oxidation powers, were tethered with different linkers to either the 5,- or 3,-phosphate end of the probe strand before hybridization with the complementary strand. These systems were studied by time-resolved emission spectroscopy, UV/Vis absorption experiments, PAGE and MS (ESI) analyses. The best yields of photocrosslinking (45,%) obtained with [Ru(tap)3]2+ tethered to the 3,-position are due to (i) a higher oxidation power of the complex and (ii) its attachment at the 3,-position. Indeed, this tethering favours the interaction of the Ru compound with the duplex and, therefore, inhibits its photodechelation. This work allows better design of sequence-specific DNA photodamaging agents prior to biological applications.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Stability of Hoogsteen -Type Triplexes , Electrostatic Attraction between Duplex Backbone and Triplex-Forming Oligonucleotide (TFO) Using an Intercalating ConjugateHELVETICA CHIMICA ACTA, Issue 5 2008Daniel Globisch Abstract Syntheses are described for two novel twisted intercalating nucleic acid (TINA) monomers where the intercalator comprises a benzene ring linked to a naphthalimide moiety via an ethynediyl bridge. The intercalators Y and Z have a 2-(dimethylamino)ethyl and a methyl residue on the naphthalimide moiety, respectively. When used as triplex-forming oligonucleotides (TFOs), the novel naphthalimide TINAs show extraordinary high thermal stability in Hoogsteen -type triplexes and duplexes with high discrimination of mismatch strands. DNA Strands containing the intercalator Y show higher thermal triplex stability than DNA strands containing the intercalator Z. This observation can be explained by the ionic interaction of the protonated dimethylamino group under physiological conditions, targeting the negatively charged phosphate backbone of the duplex. This interaction leads to an extra binding mode between the TFO and the duplex, in agreement with molecular-modeling studies. We believe that this is the first example of an intercalator linking the TFO to the phosphate backbone of the duplex by an ionic interaction, which is a promising tool to achieve a higher triplex stability. [source] Design and Nanofabrication of Superconductor Ceramic Strands and Customized LeadsINTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 2 2004Anatoly E. Rokhvarger We made possible an engineering application of the 18-year-old Nobel Prize-winning discovery of High Temperature Superconductor (HTS) ceramic particles. Guided by certain theories of physics and nano-science, we created the ceramic-silicone nanofabrication method where a silicone additive controls both the nanostructural evolution of the magnetically oriented HTS ceramic nano-grains by a 3D polymeric matrix scaffold and thermally induced nano-phase transformation. These result in the sintered granular superconductor ceramic composite material with the desirable superconducting nano-phase composition and 3D nanostructure including vortex-pinning network. The prototype HTS samples were nanofabricated in the form of adhesion substrate coated strands or surfaces or variously shaped bulk leads. [source] Evidence-Based Strategies for Reading Instruction of Older Students with Learning DisabilitiesLEARNING DISABILITIES RESEARCH & PRACTICE, Issue 2 2008Greg Roberts Over a quarter of 8th-grade students and more than one-third of 4th graders do not read well enough to understand important concepts and acquire new knowledge from grade-level text. For students with learning disabilities, the numbers are more troubling. This article describes features of evidence-based instruction for students who continue to struggle with reading in late elementary, middle, and high school. Recommendations are organized into 5 areas that are critical to the reading improvement of older struggling readers: (1) word study, (2) fluency, (3) vocabulary, (4) comprehension, and (5) motivation. Much of the content in this article reflects our efforts with the Special Education and Reading Strands at the National Center on Instruction, funded by the Office of Special Education Programs and the Office of Elementary and Secondary Education. Two reports, both available at http://www.centeroninstruction.org/, have particular relevance,Interventions for Adolescent Struggling Readers: A Meta-Analysis with Implications for Practice and Academic Literacy Instruction for Adolescents: A Guidance Document from the Center on Instruction. [source] Dynamic Cross-Linking Is Retained in Duplex DNA after Multiple Exchange of Strands,ANGEWANDTE CHEMIE, Issue 34 2010Huan Wang Dr. Stränge kommen und gehen , die Vernetzung bleibt: Dynamische kombinatorische Systeme können auf Veränderungen der Umgebung reagieren. Dies wurde nun auch für die DNA-Vernetzung basierend auf der reversiblen Alkylierung eines Chinonmethid-Intermediats gezeigt (siehe Bild). [source] Rapid model building of ,-sheets in electron-density mapsACTA CRYSTALLOGRAPHICA SECTION D, Issue 3 2010Thomas C. Terwilliger A method for rapidly building ,-sheets into electron-density maps is presented. ,-Strands are identified as tubes of high density adjacent to and nearly parallel to other tubes of density. The alignment and direction of each strand are identified from the pattern of high density corresponding to carbonyl and C, atoms along the strand averaged over all repeats present in the strand. The ,-strands obtained are then assembled into a single atomic model of the ,-sheet regions. The method was tested on a set of 42 experimental electron-density maps at resolutions ranging from 1.5 to 3.8,Å. The ,-sheet regions were nearly completely built in all but two cases, the exceptions being one structure at 2.5,Å resolution in which a third of the residues in ,-sheets were built and a structure at 3.8,Å in which under 10% were built. The overall average r.m.s.d. of main-chain atoms in the residues built using this method compared with refined models of the structures was 1.5,Å. [source] Verbundverhalten von vorgespannten Litzen in UHPCBETON- UND STAHLBETONBAU, Issue 6 2010Teil 1: Versuche zur Verbundfestigkeit und zur Übertragungslänge Spannbeton; Versuche; Bewehrung; Baustoffe Abstract Ultra-Hochfester Beton (UHPC = Ultra-High Performance Concrete) ist hervorragend geeignet für vorgespannte Bauteile. Um eine sichere und dennoch wirtschaftliche Bemessung von vorgespannten Trägern mit sofortigem Verbund vornehmen zu können, muss das Verankerungsverhalten der Litzen bekannt sein. Die hohen Verbundfestigkeiten führen zu kurzen Übertragungslängen und verbessern dadurch die Querkrafttragfähigkeit. Bei Vorspannung mit sofortigem Verbund ist eine Mindestbetondeckung entscheidend, um Längsrisse im Verankerungsbereich zu vermeiden, die einen erheblichen Verlust an Verbundfestigkeit und im Extremfall ein Verankerungsversagen zur Folge haben. In diesem Beitrag, der im Rahmen des von der Deutschen Forschungsgemeinschaft geförderten Schwerpunktprogramms SPP 1182 entstand, werden die Untersuchungsergebnisse zum Verbundverhalten von Litzen in UHPC vorgestellt. Teil 1 behandelt die experimentellen Untersuchungen und Teil 2 die Herleitung eines Verbundmodells zur Berechnung der Übertragungslänge. Bond Behavior of prestressed Strands in UHPC. Part 1: Tests on Bond Strength and Transfer Length Ultra-High Performance Concrete (UHPC) is an appropriate construction material for pretensioned girders. To ensure an economic and safe design a detailed knowledge of the behavior of pretensioned strands in the anchorage zone is essential. The dimension of the bond anchorage zone favors the cost-effective design of pretensioned girders, especially when the shear resistance is decisive. However, a minimum concrete cover has to be maintained to avoid splitting cracks in the transmission zone, since they lead to an uncontrolled increase in transfer length and may cause a premature anchorage failure. This paper, which resulted from the priority program SPP 1182 funded by the German Research Foundation, presents the results of investigations on the bond behavior of strands in UHPC. Part 1 deals with the experimental investigations and in part 2 a bond model is derived to design the transfer length. [source] Enantiospecific Syntheses of Copper Cubanes, Double-Stranded Copper/Palladium Helicates, and a (Dilithium),Dinickel Coronate from Enantiomerically Pure Bis-1,3-diketones,Solid-State Self-Organization Towards Wirelike Copper/Palladium Strands,CHEMISTRY - A EUROPEAN JOURNAL, Issue 5 2008Abstract Enantiomerically pure, vicinal diols 1 afforded in a two-step synthesis (etherification and subsequent Claisen condensation) chiral bis-1,3-diketones H2L(S,S) (3,a,c) with different substitution patterns. Reaction of these C2 -symmetric ligands with various transition-metal acetates in the presence of alkali ions generated distinct polynuclear aggregates 4,8 by diastereoselective self-assembly. Starting from copper(II) acetate monohydrate and depending on the ratio of transition-metal ion to alkali ion to ligand, chiral tetranuclear copper(II) cubanes (C,C,C,C)-[Cu4(L(S,S))2(OMe)4] (4,a,c) or dinuclear copper(II) helicates (P)-[Cu2(L(S,S))2] (5) could be synthesized with square-pyramidal and square-planar coordination geometry at the metal center. In analogy to the last case, with palladium(II) acetate double-stranded helical systems (P)-[Pd2(L(S,S))2] (6,7) were accessible exhibiting a linear self-organization of ligand-isolated palladium filaments in the solid state with short inter- and intramolecular metal distances. Finally, the introduction of hexacoordinate nickel(II) in combination with lithium hydroxide monohydrate and chiral ligand H2L(S,S) (3,a) allowed the isolation of enantiomerically pure dinuclear nickel(II) coronate [(Li,MeOH)2,{(,,,)-Ni2(L(S,S))2(OMe)2}] (8) with two lithium ions in the voids, defined by the oxygen donors in the ligand backbone. The high diastereoselectivity, induced by the chiral ligands, during the self-assembly process in the systems 4,8 could be exemplarily proven by circular dichroism spectroscopy for the synthesized enantiomers of the chiral copper(II) cubane 4,a and palladium(II) helicate 6. [source] Tuning the Polarization Along Linear Polyaromatic Strands for Rationally Inducing Mesomorphism in Lanthanide Nitrate ComplexesCHEMISTRY - A EUROPEAN JOURNAL, Issue 6 2007Emmanuel Terazzi Dr. Abstract The opposite orientation of the ester spacers in the rodlike ligands L,4C12 (benzimidazole-OOC-phenyl) and L,5C12 (benzimidazole-COO-phenyl) drastically changes the electronic structure of the aromatic systems, without affecting their meridional tricoordination to trivalent lanthanides, LnIII, and their thermotropic liquid crystalline (i.e., mesomorphic) behaviors. However, the rich mesomorphism exhibited by the complexes [Ln(L,4C12)(NO3)3] (Ln=La,Lu) vanishes in [Ln(L,5C12)(NO3)3], despite superimposable molecular structures and comparable photophysical properties. Density functional theory (DFT) and time-dependant DFT calculations performed in the gas phase show that the inversion of the ester spacers has considerable effects on the electronic structure and polarization of the aromatic groups along the strands, which control residual intermolecular interactions responsible for the formation of thermotropic liquid-crystalline phases. As a rule of thumb, an alternation of electron-poor and electron-rich aromatic rings favors intermolecular interactions between the rigid cores and consequently mesomorphism, a situation encountered for L,4C12, L,5C12, [Ln(L,4C12)(NO3)3], but not for [Ln(L,5C12)(NO3)3]. The intercalation of an additional electron-rich diphenol ring on going from [Ln(L,5C12)(NO3)3] to [Ln(L,6C12)(NO3)3] restores mesomorphism despite an unfavorable orientation of the ester spacers, in agreement with our simple predictive model. [source] Programming Heteropolymetallic Lanthanide Helicates: Thermodynamic Recognition of Different Metal Ions Along the StrandsCHEMISTRY - A EUROPEAN JOURNAL, Issue 5 2004Sébastien Floquet Dr. Abstract Under stoichiometric conditions, the segmental tris-tridentate ligand L9 assembles with two different lanthanide metal ions Ln1 and Ln2 (Ln1, Ln2=La, Nd, Sm, Eu, Yb, Lu, Y) to give mixtures of the heterotrimetallic triple-stranded helicates [(Ln1)x(Ln2)3,x(L9)3]9+ (x=0,3) in acetonitrile. The combination of qualitative (ESI-MS) and quantitative (1H NMR) speciations provides a set of thermodynamic data that were analysed with various statistical chemical models. A satisfying description requires the consideration of different affinities for the terminal N6O3 sites (k) and for the central N9 site (k) for each specific lanthanide. The nontrivial dependence of these parameters on the ionic radius provides size-discriminating effects that favour the formation of heterotrimetallic helicates in which the central site is occupied by the larger metal of the pair. Combining the latter enthalpic driving forces with entropic contributions due to specific stoichiometric conditions allows partial selection (i.e., programming) of a specific heterotrimetallic species in solution, which can be isolated by crystallisation, as demonstrated for [Eu2.04La0.96(L9)3](CF3SO3)9(CH3NO2)9 (1, Eu2.04La0.96C207H222N48O51S9F27, monoclinic, P21/c, Z=4) in which the cation [EuLaEu(L9)3]9+ is the major component in the crystal. The scope and limitation of this approach is discussed together with the conditions for explicitly considering intermetallic interaction parameters uLn1Ln2 in more sophisticated chemical models. [source] Circular dichroism spectroscopy of conformers of (guanine + adenine) repeat strands of DNACHIRALITY, Issue 7 2003Iva Kejnovská Abstract (Guanine+adenine) strands of DNA are known to associate into guanine tetraplexes, homodimerize into parallel or antiparallel duplexes, and fold into a cooperatively melting single strand resembling the protein alpha helix. Using CD spectroscopy and other methods, we studied how this conformational polymorphism depended on the primary structure of DNA. The study showed that d(GGGA)5 and d(GGA)7 associated into homoduplexes at low salt or in the presence of LiCl but were prone to guanine tetraplex formation, especially in the presence of KCl. In addition, they yielded essentially the same CD spectrum in the presence of ethanol as observed with the ordered single strand of d(GA)10. Strands of d(GA)10, d(GGAA)5, d(GAA)7, and d(GAAA)5 associated into homoduplexes in both LiCl and KCl solutions, but not into guanine tetraplexes. d(GAAA)5 and d(GAA)7 further failed to form the single-stranded conformer in aqueous ethanol. Adenine protonation, however, stabilized the single-stranded conformer even in these adenine-rich fragments. The ordered single strands, homoduplexes as well as the guanine tetraplexes, all provided strikingly similar CD spectra, indicating that all of the conformers shared similar base stacking geometries. The increasing adenine content only decreased the conformer thermostability. Chirality 15:584,592, 2003. © 2003 Wiley-Liss, Inc. [source] Transforming the Developmental Welfare State in East AsiaDEVELOPMENT AND CHANGE, Issue 3 2005Huck-ju Kwon This article attempts to explain changes and continuity in the developmental welfare states in Korea and Taiwan within the East Asian context. It first elaborates two strands of welfare developmentalism (selective vs. inclusive), and establishes that the welfare state in both countries fell into the selective category of developmental welfare states before the Asian economic crisis of 1997. The key principles of the selective strand of welfare developmentalism are productivism, selective social investment and authoritarianism; inclusive welfare development is based on productivism, universal social investment and democratic governance. The article then argues that the policy reform toward an inclusive welfare state in Korea and Taiwan was triggered by the need for structural reform in the economy. The need for economic reform, together with democratization, created institutional space in policy-making for advocacy coalitions, which made successful advances towards greater social rights. Finally, the article argues that the experiences of Korea and Taiwan counter the neo-liberal assertion that the role of social policy in economic development is minor, and emphasizes that the idea of an inclusive developmental welfare state should be explored in the wider context of economic and social development. [source] The Tension in Wittgenstein's Diagnosis of ScepticismDIALECTICA, Issue 3 2000Reid Buchanan I argue that Wittgenstein's rejection of scepticism in On Certainty rests on the view that epistemic concepts such as,doubt,,knowledge',,justification'and so on, cannot be intelligibly applied to the common sense propositions that traditional sceptical arguments appear to undermine. I detect two strands in On Certainty in support of this view. I attempt to show that neither of these strands adequately establishes the thesis, and that they point to a tension in Wittgenstein's treatment of scepticism. I argue that the first strand is dogmatic, but accords with the constraints of Wittgenstein's method, while the second strand avoids the dogmatism of the first at the cost of violating these constraints. [source] Does disturbance of self underlie social cognition deficits in schizophrenia and other psychotic disorders?EARLY INTERVENTION IN PSYCHIATRY, Issue 2 2009Barnaby Nelson Abstract Aim: Although the different approaches to psychosis research have made significant advances in their own fields, integration between the approaches is often lacking. This paper attempts to integrate a strand of cognitive research in psychotic disorders (specifically, social cognition research) with phenomenological accounts of schizophrenia and other psychotic disorders. Method: The paper is a critical investigation of phenomenological models of disturbed selfhood in schizophrenia in relation to cognitive theories of social cognition in psychotic disorders. Results: We argue that disturbance of the basic sense of self, as articulated in the phenomenological literature, may underlie the social cognition difficulties present in psychotic disorders. This argument is based on phenomenological thinking about self-presence (,ipseity') being the primary or most basic ground for the intentionality of consciousness , that is, the directedness of consciousness towards others and the world. A disruption in this basic ground of conscious life has a reverberating effect through other areas of cognitive and social functioning. We propose three routes whereby self-disturbance may compromise social cognition, including dissimilarity, disruption of lived body and disturbed mental coherence. Conclusions: If this model is supported, then social cognition difficulties may be thought of as a secondary index or marker of the more primary disturbance of self in psychotic disorders. Further empirical work examining the relationship between cognitive and phenomenological variables may be of value in identifying risk markers for psychosis onset, thus contributing to early intervention efforts, as well as in clarifying the essential psychopathological features of schizophrenia and other psychotic disorders. [source] Real Time Electrochemical Monitoring of DNA/PNA Dissociation by Melting Curve AnalysisELECTROANALYSIS, Issue 14 2009Xiaoteng Luo Abstract An immobilization-free electrochemical method is reported for real-time monitoring of the DNA hybrid dissociation between a ferrocene labeled peptide nucleic acid (PNA) and a fully-complementary or single-base-mismatched DNA. This method takes advantages of electrostatic charge characteristics and interactions among the neutrally charged PNA, the negatively charged DNA and the negatively charged electrode surface made of indium tin oxide (ITO). When a ferrocene labeled PNA (Fc-PNA) sequence is hybridized to a complementary DNA strand, electrostatic repulsion between the negatively charged PNA/DNA hybrid and the negative ITO surface retards the diffusion of the electroactive Fc to the electrode, resulting in a much reduced electrochemical signal. On the other hand, when the Fc-PNA is dissociated from the hybrid at elevated temperatures, the neutrally charged Fc-PNA easily diffuses to the electrode with an enhanced electrochemical signal. Therefore, an electrochemical melting curve of the Fc-PNA/DNA hybrid can be obtained by measuring the Fc signal with the increasing temperature. This strategy allows monitoring of the dissociation of the DNA hybrid in real time, which might lead to a simple detection method for single nucleotide polymorphism (SNP) analysis. [source] An Aptamer-Based Bound/Free Separation System for Protein DetectionELECTROANALYSIS, Issue 11 2009Mieko Fukasawa Abstract Aptamer hybridizes with its complementary strand. However, the complementary strand has difficulties to hybridize with the aptamer bound to a target because the aptamer forms higher-order structures. Exploiting this property, we developed simple bound/free separation systems for thrombin and IgE detection. The complementary strand was immobilized onto beads and the aptamer was labeled with pyrroquinoline quinone glucose dehydrogenase (PQQGDH). In the absence of a target, the aptamer is trapped by beads, whereas in the presence of a target, the aptamer bound to the target is not trapped. Thus the aptamer-target complexes can be recovered easily and detected by PQQGDH activity. This system allow the detection of 270,pM thrombin and 1,nM IgE. [source] Electrochemical Aptasensor for the Determination of Cocaine Incorporating Gold Nanoparticles ModificationELECTROANALYSIS, Issue 13 2008Xiaoxia Li Abstract A novel electrochemical aptasensor incorporating a signal enhancement for the determination of cocaine was designed. Gold nanoparticles were self-assembled onto the surface of a gold electrode through 1,6-hexanedithiol. A bifunctional derivative of the 32-base cocaine-binding aptamer with a redox-active ferrocene moiety and a thiol linker group at the termini of the strand was self-assembled onto the surface of gold nanoparticles. The oxidation peak current is linearly related to the concentration of cocaine from 1.0 to 15.0,,M with a detection limit of 0.5,,M. It was found that the sensitivity of the aptasensor with gold nanoparticles modification was ca. 10-fold higher than that of the aptasensor without gold nanoparticles modification. This work demonstrates that gold nanoparticles-assembled gold electrode provides a promising platform for immobilizing aptamer and enhancing the sensitivity. [source] Preparation of Nanogapped Gold Nanoparticle Array for DNA DetectionELECTROANALYSIS, Issue 4 2008Shiho Tokonami Abstract A novel DNA detection technique using a gold nanoparticle array film electrode has been reported here. The gold nanoparticles molecularly linked with binder molecule (1,10-decanedithiol) were separated 1.3,nm from each other, and the DNA conductivity change from single to double strand was measured by monitoring a voltage drop across the particles, between which a probe of a 12-mer oligonucleotide was immobilized. In adding a complementary oligonucleotide on the nanoparticle film chip, an immediate decrease in the film resistance (ca. 1.4 ,) due to a hybridization event occurred in a reproducible manner with this simple setup. In the paper, we have an interest in the primary sensing properties; effect of the film resistance on the sensor response, dependence of the resistance change on the DNA concentration, and the performance of the system for DNA detection including single nucleotide polymorphisms were described. [source] Mutagenic repair of DNA interstrand crosslinksENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 6 2010Xi Shen Abstract Formation of DNA interstrand crosslinks (ICLs) in chromosomal DNA imposes acute obstruction of all essential DNA functions. For over 70 years bifunctional alkylators, also known as DNA crosslinkers, have been an important class of cancer chemotherapeutic regimens. The mechanisms of ICL repair remains largely elusive. Here, we review a eukaryotic mutagenic ICL repair pathway discovered by work from several laboratories. This repair pathway, alternatively termed recombination-independent ICL repair, involves the incision activities of the nucleotide excision repair (NER) mechanism and lesion bypass polymerase(s). Repair of the ICL is initiated by dual incisions flanking the ICL on one strand of the double helix; the resulting gap is filled in by lesion bypass polymerases. The remaining lesion is subsequently removed by a second round of NER reaction. The mutagenic repair of ICL likely interacts with other cellular mechanisms such as the Fanconi anemia pathway and recombinational repair of ICLs. These aspects will also be discussed. Environ. Mol. Mutagen., 2010. © 2010 Wiley-Liss, Inc. [source] CCL22-induced responses are powerfully enhanced by synergy inducing chemokines via CCR4: evidence for the involvement of first ,-strand of chemokineEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 3 2005Silvia Sebastiani Abstract In an attempt to clarify how cells integrate the signals provided by multiple chemokines expressed during inflammation, we have uncovered a novel mechanism regulating leukocyte trafficking. Our data indicate that the concomitant exposure to CCR4 agonists and CXCL10/IP-10 strongly enhances the chemotactic response of human T lymphocytes. This enhancement is synergistic rather than additive and occurs via CCR4 since it persists after CXCR3 blockade. Besides chemotaxis, other cellular responses are enhanced upon stimulation of CCR4-transfected cells with CCL22/MDC plus CXCL10. Several other chemokines in addition to CXCL10 were able to increase CCL22-mediated chemotaxis. The first ,-strand of the chemokine structure is highly and specifically implicated in this phenomenon, as established using synergy-inducing and non-synergy-inducing chimeric chemokines. As shown in situ for skin from atopic and allergic contact dermatitis patients, this organ becomes the ideal environment in which skin-homing CCR4+ T lymphocytes can accumulate under the stimulus offered by CCR4 agonists, together with the synergistic chemokines that are concomitantly expressed. Overall, our results indicate that chemokine-induced synergism strengthens leukocyte recruitment towards tissues co-expressing several chemokines. [source] | |||||||||||||||||||||||||||||||||||||||||||||||||