Distribution by Scientific Domains

Terms modified by Lie

  • lie algebra
  • lie detection
  • lie group

  • Selected Abstracts


    ADDICTION, Issue 1 2007
    No abstract is available for this article. [source]

    Multiple promoter elements required for leukemia inhibitory factor-stimulated M2 muscarinic acetylcholine receptor promoter activity

    George S. Laszlo
    Abstract Treatment of neuronal cells with leukemia inhibitory factor (LIF) results in increased M2 muscarinic acetylcholine receptor promoter activity. We demonstrate here that multiple promoter elements mediate LIF stimulation of M2 gene transcription. We identify a LIF inducible element (LIE) in the M2 promoter with high homology to a cytokine-inducible ACTG-containing sequence in the vasoactive intestinal peptide promoter. Mutagenesis of both a STAT (signal transducers and activators of transcription) element and the LIE in the M2 promoter is required to attenuate stimulation of M2 promoter activity by LIF completely. Mobility shift assays indicate that a LIF-stimulated complex binds to a 70 base pair M2 promoter fragment. Furthermore, a STAT element within this fragment can bind to LIF-stimulated nuclear STAT1 homodimers in vitro. Mutagenesis experiments show that cytokine-stimulated activation of M2 promoter activity requires tyrosine residues on glycoprotein 130 (gp130) that are also required for both STAT1 and STAT3 activation. Dominant negative STAT1 or STAT3 can block LIF-stimulated M2 promoter activity. Real-time RT-PCR analysis indicates that LIF-stimulated induction of M2 mRNA is partially dependent on protein synthesis. These results show that regulation of M2 gene transcription in neuronal cells by LIF occurs through a complex novel mechanism that is dependent on LIE, STAT and de novo protein synthesis. [source]

    Stabilization of an underactuated bottom-heavy airship via interconnection and damping assignment

    Zili Cai
    Abstract This paper focuses on feedback stabilization of a neutrally buoyant and bottom-heavy airship actuated by only five independent controls (with the rolling motion underactuated). The airship is modelled as an eudipleural submerged rigid body whose dynamics is formulated as a Hamiltonian system with respect to a Lie,Poisson structure. By exploiting the geometrical structure and using the so-called interconnection and damping assignment (IDA) passivity-based methodology for port-controlled Hamiltonian systems, state feedback control laws asymptotically stabilizing two typical motions are designed via La Salle invariance principle and Chetaev instability theorem. Simulation results verify the control laws. Copyright © 2007 John Wiley & Sons, Ltd. [source]

    How the Laws of Economics Lie

    Ian Hunt
    First page of article [source]

    Cis-Acting Intronic Elements That Regulate Cartilage-Specific Alternative Splicing of the Type II Collagen (Col2) Pre-mRNA Lie at or Near Splice Site Junction Sequences Flanking Exon 2 of the Gene,

    Takayuki Nishiyama
    Abstract Knowledge of the cis-acting elements is required for identifying trans-acting splicing factors underlying cartilage-specific alternative splicing of Col2 pre-mRNA. By performing desired deletions in the mouse Col2 pre-mRNA, location of the intronic cis-acting elements was narrowed down to be at or near splice-junction sequences flanking exon 2 of the gene. Introduction: Type II collagen (Col2) pre-mRNA undergoes cartilage-specific alternative splicing involving exon 2 during chondrocyte differentiation. Thus, the trans-acting protein factors that regulate the splicing are associated with the differentiation of chondrocytes. Knowledge of the cognate cis-acting elements is necessary to eventually identify the trans-acting factors. Materials and Methods: To localize the cis-acting sequences, we created several deletions within a minigene containing exon 1 to exon 4 of mouse Col 2 gene and evaluated alternative splicing of the resulting pre-mRNAs in ATDC5 cells, a model of insulin-stimulated chondrocyte differentiation. The first deletion reduced intron 1 from 3799 to 259 bp, the second reduced intron 2 from 1108 to 94 bp, the third combined the above two deletions, and the fourth was derived from the third by removing intron 3 and exon 4. ATDC5 cells harboring these constructs were cultured for up to 21 days with or without insulin. Alternative splicing was evaluated by determining the ratio of Col2B (lacks exon 2) to Col2A (has exon 2) RNAs by reverse transcription-polymerase chain reaction. Results: The deletion in intron 1 had no effect on the alternative splicing while other deletions affected splicing (demonstrated by the presence of splicing intermediates) in cells cultured without insulin or with insulin for 1 week. The splicing intermediates were not seen from any construct when cells were cultured longer (14,21 days) with insulin. Conclusion: These results show that the 259-bp intron 1, the 94-bp intron 2, and exon 2 sequences retained in the fourth construct provide cis-acting signal sufficient for insulin-induced cartilage-specific alternative splicing of Col2 pre-mRNA. [source]

    Symmetry group classification of ordinary differential equations: Survey of some results

    F. M. Mahomed
    Abstract After the initial seminal works of Sophus Lie on ordinary differential equations, several important results on point symmetry group analysis of ordinary differential equations have been obtained. In this review, we present the salient features of point symmetry group classification of scalar ordinary differential equations: linear nth-order, second-order equations as well as related results. The main focus here is the contributions of Peter Leach, in this area, in whose honour this paper is written on the occasion of his 65th birthday celebrations. Copyright © 2007 John Wiley & Sons, Ltd. [source]

    A Local/Global Approach to Mesh Parameterization

    Ligang Liu
    Abstract We present a novel approach to parameterize a mesh with disk topology to the plane in a shape-preserving manner. Our key contribution is a local/global algorithm, which combines a local mapping of each 3D triangle to the plane, using transformations taken from a restricted set, with a global "stitch" operation of all triangles, involving a sparse linear system. The local transformations can be taken from a variety of families, e.g. similarities or rotations, generating different types of parameterizations. In the first case, the parameterization tries to force each 2D triangle to be an as-similar-as-possible version of its 3D counterpart. This is shown to yield results identical to those of the LSCM algorithm. In the second case, the parameterization tries to force each 2D triangle to be an as-rigid-as-possible version of its 3D counterpart. This approach preserves shape as much as possible. It is simple, effective, and fast, due to pre-factoring of the linear system involved in the global phase. Experimental results show that our approach provides almost isometric parameterizations and obtains more shape-preserving results than other state-of-the-art approaches. We present also a more general "hybrid" parameterization model which provides a continuous spectrum of possibilities, controlled by a single parameter. The two cases described above lie at the two ends of the spectrum. We generalize our local/global algorithm to compute these parameterizations. The local phase may also be accelerated by parallelizing the independent computations per triangle. [source]

    Crystal structure of a ternary mononuclear copper (II) complex: 4-chloro-3-methyl-6[(N-2-picolyl)-1,-iminomethyl]phenolato copper(II)perchlorate

    S. M. Malathy Sony
    Abstract The complex crystallizes in monoclinic space group P21/n with unit cell parameters a = 7.295(4), b = 19.627(5), c = 12.770(4) Ĺ, , = 101.25(4)ş, V = 1793.2(12) Ĺ3, Z = 4, , = 1.684 Mg/m3 at T = 293(2)K. The structure was solved by Patterson method and refined by full-matrix least-squares procedures to final R = 0.0387 using 2906 observed reflections. The asymmetric unit of the complex contains a mononuclear tridentate ligand, a perchlorate group and a methanol molecule. The compound crystallizes as parallel layers of polymeric complex bridged through perchloarate groups. The molecular CuN2OO,O,,2 chromophore involves an elongated rhombic octahedral structure and the Cu-ligand bond shows greater disparity. The five-membered chelate ring and the pyridine ring lie in the same plane while the six membered chelate ring assumes sofa conformation. A strong O-H,O inter molecular interaction plays a key role in the formation of dimer along b-axis. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    The Allantoic Core Domain: New insights into development of the murine allantois and its relation to the primitive streak

    Karen M. Downs
    Abstract The whereabouts and properties of the posterior end of the primitive streak have not been identified in any species. In the mouse, the streak's posterior terminus is assumed to be confined to the embryonic compartment, and to give rise to the allantois, which links the embryo to its mother during pregnancy. In this study, we have refined our understanding of the biology of the murine posterior primitive streak and its relation to the allantois. Through a combination of immunostaining and morphology, we demonstrate that the primitive streak spans the posterior extraembryonic and embryonic regions at the onset of the neural plate stage (,7.0 days postcoitum, dpc). Several hours later, the allantoic bud emerges from the extraembryonic component of the primitive streak (XPS). Then, possibly in collaboration with overlying allantois-associated extraembryonic visceral endoderm, the XPS establishes a germinal center within the allantois, named here the Allantoic Core Domain (ACD). Microsurgical removal of the ACD beyond headfold (HF) stages resulted in the formation of allantoic regenerates that lacked the ACD and failed to elongate; nevertheless, vasculogenesis and vascular patterning proceeded. In situ and transplantation fate mapping demonstrated that, from HF stages onward, the ACD's progenitor pool contributed to the allantois exclusive of the proximal flanks. By contrast, the posterior intraembryonic primitive streak (IPS) provided the flanks. Grafting the ACD into TC/TC hosts, whose allantoises are significantly foreshortened, restored allantoic elongation. These results revealed that the ACD is essential for allantoic elongation, but the cues required for vascularization lie outside of it. On the basis of these and previous findings, we conclude that the posterior primitive streak of the mouse conceptus is far more complex than was previously believed. Our results provide new directives for addressing the origin and development of the umbilical cord, and establish a novel paradigm for investigating the fetal/placental relationship. Developmental Dynamics 238:532,553, 2009. © 2009 Wiley-Liss, Inc. [source]

    Atlas of the developing inner ear in zebrafish

    Michele Miller Bever
    Abstract This report provides a description of the normal developing inner ear of the zebrafish, Danio rerio, with special focus on the pars inferior. Zebrafish specimens, ranging in age from 3 to 30 days postfertilization (dpf), were processed for standard histologic sections or with a paint-fill method to show three-dimensional morphogenesis of the membranous labyrinth. Adult zebrafish (age 2 years) were also processed for inner ear paint-fills. Although development of the semicircular canals occurs rapidly (by 3 dpf), the pars inferior develops more gradually during days 5,20 postfertilization. A rudimentary endolymphatic duct emerges by 8 dpf. Differentiated hair cells of the lagenar macula are evident by 15 dpf, in a chamber located lateral and posterior to the saccule. By 20 dpf, the saccule itself is separated from the utricle, but remains connected by means of the utriculosaccular foramen. The maculae neglectae, each with differentiated hair cells, lie on the floor of the utricle near this foramen. A medial connection between the sacculi of right and left ears, the transverse canal, is also complete by 20 dpf. A ridge of mesenchyme, previously undescribed, bisects the saccule in zebrafish fry at 20,30 dpf. The images in the paint-fill atlas should provide a baseline for future studies of mutant zebrafish ears. © 2002 Wiley-Liss, Inc. [source]

    Contribution of rarity and commonness to patterns of species richness

    ECOLOGY LETTERS, Issue 2 2004
    Jack J. Lennon
    Abstract There is little understanding in ecology as to how biodiversity patterns emerge from the distribution patterns of individual species. Here we consider the question of the contributions of rare (restricted range) and common (widespread) species to richness patterns. Considering a species richness pattern, is most of the spatial structure, in terms of where the peaks and troughs of diversity lie, caused by the common species or the rare species (or neither)? Using southern African and British bird richness patterns, we show here that commoner species are most responsible for richness patterns. While rare and common species show markedly different species richness patterns, most spatial patterning in richness is caused by relatively few, more common, species. The level of redundancy we found suggests that a broad understanding of what determines the majority of spatial variation in biodiversity may be had by considering only a minority of species. [source]


    ECONOMIC AFFAIRS, Issue 2 2004
    Anthony de Jasay
    Institutions, customs, laws are often, and sometimes implausibly, credited with efficiency. They serve a good purpose and if they had not arisen, we would have invented them. The claim is reassuring, though it may be no more than a pious lie. The creation of the state by social contract, and the adoption of supposedly rational customs by primitive peoples, serve as examples. Interpreting the welfare state as a mutual insurance scheme from which all can expect to profit is a classic of the kind. [source]

    A European Legal Method?

    EUROPEAN LAW JOURNAL, Issue 1 2009
    On European Private Law, Scientific Method
    This article examines the relationship between European private law and scientific method. It argues that a European legal method is a good idea. Not primarily because it will make European private law scholarship look more scientific, but because a debate on the method of a normative science necessarily has to be a debate on its normative assumptions. In other words, a debate on a European legal method will have much in common with the much desired debate on social justice in European law. Moreover, it submits that, at least after the adoption of the Common Frame of Reference by the European institutions, European contract law can be regarded as a developing multi-level system that can be studied from the inside. Finally, it concludes that the Europeanisation of private law is gradually blurring the dividing line between the internal and external perspectives, with their respective appropriate methods, in two mutually reinforcing ways. First, in the developing multi-level system it is unclear where the external borders of the system lie, in particular the borders between Community law and national law. Second, because of the less formal legal culture the (formerly) external perspectives, such as the economic perspective, have easier access and play an increasing role as policy considerations. [source]

    The Langerhans' cell-like cell lines XS52 and XS106 express mRNA for ciliary neurotrophic factor and neurotrophic factor 4/5

    K. Seiffert
    Neurotrophins are responsible for the survival and outgrowth of nerves within the peripheral and central nervous systems. These factors include brain-derived neurotrophic factor (BDNF), CNTF, NT 3, and NT4/5. We have previously shown that LCs lie in close proximity to nerves and that several neuropeptides regulate LC function, implying that nerves send regulatory signals to LCs. To evaluate the possibility that LC signal nerves by release of neurotrophins, we examined LC expression of neurotrophins by RT-PCR. To eliminate the possibility of contaminating keratinocytes in highly enriched LC preparations, we utilized the LC-like cell lines XS52 (BALB/c derived) and XS106 (A/J derived) for initial experiments. The RNA obtained was digested with DNase to ensure complete absence of genomic DNA. Several independent RT-PCRs revealed expression of bands of the expected size for CTNF and NT4/5, but not for BDNF and NT3 in XS106 and XS52 cells. In contrast, the transformed keratinocyte cell line PAM212 expressed BDNF, as well as CTNF and NT4/5. Preliminary experiments with purified LC confirm the expression of CTNF and NT4/5 and also show the expression of BDNF. However, we cannot be sure that BDNF expression is not due to keratinocyte contamination. We conclude that LCs may regulate nerve cells by the release of neurotrophic factors. [source]

    Developmental programming of obesity in mammals

    P. D. Taylor
    Converging lines of evidence from epidemiological studies and animal models now indicate that the origins of obesity and related metabolic disorders lie not only in the interaction between genes and traditional adult risk factors, such as unbalanced diet and physical inactivity, but also in the interplay between genes and the embryonic, fetal and early postnatal environment. Whilst studies in man initially focused on the relationship between low birth weight and risk of adult obesity and metabolic syndrome, evidence is also growing to suggest that increased birth weight and/or adiposity at birth can also lead to increased risk for childhood and adult obesity. Hence, there appears to be increased risk of obesity at both ends of the birth weight spectrum. Animal models, including both under- and overnutrition in pregnancy and lactation lend increasing support to the developmental origins of obesity. This review focuses upon the influence of the maternal nutritional and hormonal environment in pregnancy in permanently programming appetite and energy expenditure and the hormonal, neuronal and autocrine mechanisms that contribute to the maintenance of energy balance in the offspring. We discuss the potential maternal programming ,vectors' and the molecular mechanisms that may lead to persistent pathophysiological changes resulting in subsequent disease. The perinatal environment, which appears to programme subsequent obesity, provides a potential therapeutic target, and work in this field will readily translate into improved interventional strategies to stem the growing epidemic of obesity, a disease which, once manifest, has proven particularly resistant to treatment. [source]

    The Physiological Basis of Uterine Contractility: A Short Review

    S. Wray
    In this review we discuss our current understanding of the cellular basis of uterine contractility, highlighting those areas requiring further study. It is clear that the basic processes of excitation-contraction coupling lie within the myometrial cell, and that these may be modified by agonists. Pacemaker acitivity, however, remains a mystery. The contribution of extracellular calcium entry to contraction is shown to be vital, whilst the role of the sarcoplasmic reticulum remains controversial. Much current experimental focus is on pathways controlling and regulating contraction, and we discuss sensitisation mechanisms and question their role in intact uterine preparations. [source]

    The C-terminal region of CHD3/ZFH interacts with the CIDD region of the Ets transcription factor ERM and represses transcription of the human presenilin 1 gene

    FEBS JOURNAL, Issue 6 2007
    Martine Pastorcic
    Presenilins are required for the function of ,-secretase: a multiprotein complex implicated in the development of Alzheimer's disease (AD). We analyzed expression of the presenilin 1 (PS1) gene. We show that ERM recognizes avian erythroblastosis virus E26 oncogene homolog (Ets) motifs on the PS1 promoter located at ,10, +90, +129 and +165, and activates PS1 transcription with promoter fragments containing or not the ,10 Ets site. Using yeast two-hybrid selection we identified interactions between the chromatin remodeling factor CHD3/ZFH and the C-terminal 415 amino acids of ERM used as bait. Clones contained the C-terminal region of CHD3 starting from amino acid 1676. This C-terminal fragment (amino acids 1676,2000) repressed transcription of the PS1 gene in transfection assays and PS1 protein expression from the endogenous gene in SH-SY5Y cells. In cells transfected with both CHD3 and ERM, activation of PS1 transcription by ERM was eliminated with increasing levels of CHD3. Progressive N-terminal deletions of CHD3 fragment (amino acids 1676,2000) indicated that sequences crucial for repression of PS1 and interactions with ERM in yeast two-hybrid assays are located between amino acids 1862 and 1877. This was correlated by the effect of progressive C-terminal deletions of CHD3, which indicated that sequences required for repression of PS1 lie between amino acids 1955 and 1877. Similarly, deletion to amino acid 1889 eliminated binding in yeast two-hybrid assays. Testing various shorter fragments of ERM as bait indicated that the region essential for binding CHD3/ZFH is within the amino acid region 96,349, which contains the central inhibitory DNA-binding domain (CIDD) of ERM. N-Terminal deletions of ERM showed that residues between amino acids 200 and 343 are required for binding to CHD3 (1676,2000) and C-terminal deletions of ERM indicated that amino acids 279,299 are also required. Furthermore, data from chromatin immunoprecipitation (ChIP) indicate that CHD3/ZFH interacts with the PS1 promoter in vivo. [source]

    Highly Stable Au Nanoparticles with Tunable Spacing and Their Potential Application in Surface Plasmon Resonance Biosensors

    Shuyan Gao
    Abstract Colloidal Au-amplified surface plasmon resonance (SPR), like traditional SPR, is typically used to detect binding events on a thin noble metal film. The two major concerns in developing colloidal Au-amplified SPR lie in 1) the instability, manifested as a change in morphology following immersion in organic solvents and aqueous solutions, and 2) the uncontrollable interparticle distance, determining probe spacing and inducing steric hindrance between neighboring probe molecules. This may introduce uncertainties into such detecting techniques, degrade the sensitivity, and become the barricade hampering colloidal Au-based transducers from applications in sensing. In this paper, colloidal Au-amplified SPR transducers are produced by using ultrathin Au/Al2O3 nanocomposite films via a radio frequency magnetron co-sputtering method. Deposited Au/Al2O3 nanocomposite films exhibit superior stability, and average interparticle distances between Au nanoparticles with similar average sizes can be tuned by changing surface coverage. These characteristics are ascribed to the spacer function and rim confinement of dielectric Al2O3 and highlight their advantages for application in optimal nanoparticle-amplified SPR, especially when the probe size is smaller than the target molecule size. This importance is demonstrated here for the binding of protein (streptavidin) targets to the probe (biotin) surface. In this case, the dielectric matrix Al2O3 is a main contributor, behaving as a spacer, tuning the concentration of Au nanoparticles, and manipulating the average interparticle distance, and thus guaranteeing an appropriate number of biotin molecules and expected near-field coupling to obtain optimal sensing performance. [source]

    Gendered Agendas: The Secrets Scholars Keep about Yorůbá-Atlantic Religion

    GENDER & HISTORY, Issue 3 2003
    J. Lorand Matory
    Whereas scholars have often described the material interests served by any given social group's selective narration of history, this article catches scholars in the act of selectively narrating Yorůbá-Atlantic cultural history in the service of their own faraway activist projects. Anthropologist Ruth Landes' re-casting of the Afro-Brazilian Candomblá religion as an instance of primitive matriarchy not only encouraged feminists abroad but also led Brazilian nationalist power-brokers to marginalise the male, and often reputedly homosexual, priests who give the lie to Landes's interpretation. In the service of a longdistance Yorůbá nationalist agenda, sociologist Oyeronke Oyewumi has declared traditional Yorůbá society ,genderless', and found, among both North American feminist scholars and Yorůbá male scholars, allies in concealing the copious evidence of gender and gender inequality in Yorůbá cultural history. What these historical constructions lack in truth value they make up for in their power to mobilise new communities and alliances around the defence of a shared secret. The article addresses how politically tendentious scholarship on gender has inspired new social hierarchies and boundaries through the truths that some high-profile scholars have chosen to silence. [source]

    Gamma regression improves Haseman-Elston and variance components linkage analysis for sib-pairs

    Mathew J. Barber
    Abstract Existing standard methods of linkage analysis for quantitative phenotypes rest on the assumptions of either ordinary least squares (Haseman and Elston [1972] Behav. Genet. 2:3,19; Sham and Purcell [2001] Am. J. Hum. Genet. 68:1527,1532) or phenotypic normality (Almasy and Blangero [1998] Am. J. Hum. Genet. 68:1198,1199; Kruglyak and Lander [1995] Am. J. Hum. Genet. 57:439,454). The limitations of both these methods lie in the specification of the error distribution in the respective regression analyses. In ordinary least squares regression, the residual distribution is misspecified as being independent of the mean level. Using variance components and assuming phenotypic normality, the dependency on the mean level is correctly specified, but the remaining residual coefficient of variation is constrained a priori. Here it is shown that these limitations can be addressed (for a sample of unselected sib-pairs) using a generalized linear model based on the gamma distribution, which can be readily implemented in any standard statistical software package. The generalized linear model approach can emulate variance components when phenotypic multivariate normality is assumed (Almasy and Blangero [1998] Am. J. Hum Genet. 68: 1198,1211) and is therefore more powerful than ordinary least squares, but has the added advantage of being robust to deviations from multivariate normality and provides (often overlooked) model-fit diagnostics for linkage analysis. Genet Epidemiol 26:97,107, 2004. © 2004 Wiley-Liss, Inc. [source]

    Localized ductile thrusting north of the Variscan Front, Ross Island, southwest Ireland

    GEOLOGICAL JOURNAL, Issue 1 2003
    Paul A. M. Nex
    Abstract Two thrusts occur on Ross Island: the Head of Ross Thrust and the more southerly Ross Island Thrust. These lie to the north of the Killarney,Mallow Fault (KMF), the boundary frequently interpreted as the Variscan Front. The Ross Island Thrust, exposed in outcrop and in seven borehole cores, has emplaced dark blue,grey limestones of the Courceyan Ballysteen Formation over pale grey,brown Rockfield Limestone Formation of Chadian,Holkerian age. These lithologies at Ross Island exhibit a continuum of deformation at both the micro- and macro-scale, beginning with the generation of a spaced cleavage, formed during layer parallel shortening, that was subsequently rotated into parallelism with fold axial planes. Extensional microstructures are predominant in thin section and are associated with attenuation of the fold limb. Calcite veins are also attenuated and lie parallel to a mylonitic fabric close to the thrust plane. Lithological boundaries, the prominent pressure solution cleavage and the southerly dipping limb of an asymmetrical antiform are all parallel and form a composite planar anisotropy. This has controlled the location of the ductile Ross Island Thrust, which formed during the attenuation and shearing of a common fold limb. Ductile thrusts within the limestones at Ross Island contrast with the reactivation of basin-margin extensional faults further to the south along the major KMF. The Ross Island Thrust is considered to result from deformation ahead of the major northerly propagating Variscan décollement thrust and does not necessitate a continuous décollement structure north of the KMF. Mineralization at Ross Island exhibits remobilization associated with the formation of a pressure-solution cleavage and probably pre-dates thrusting. Copyright © 2003 John Wiley & Sons, Ltd. [source]

    A study of Holocene floodplain particle size characteristics with special reference to palaeochannel infills from the upper Severn basin, Wales, UK

    GEOLOGICAL JOURNAL, Issue 2 2001
    Mark Patrick Taylor
    Abstract Multiple sedimentary units from floodplain reaches at Welshpool on the upper River Severn and at the confluence of the Afon Tanat and Afon Vyrnwy (mid-Wales, UK) were examined to ascertain if they have distinctive particle size characteristics. Changes in particle size characteristics and their possible relationship to known human and climatic impacts are also discussed. Ellipse plots of particle size characteristics from the River Severn floodplain at Welshpool show that coarse-grained outwash deposits can be clearly discriminated from channel margin or palaeochannel sediments. In contrast, at the Afon Tanat,Vyrnwy study reach, this discrimination is not seen so clearly. The relationships between age and particle size characteristics from the most sampled sedimentary environment, palaeochannel infills, were also examined. The data from the River Severn floodplain at Welshpool show that palaeochannel sediments reveal a gradual but clear increase in particle size from the mid- to late Holocene towards the present day. Sediments deposited in the period 90,160 years BP are markedly coarser. It is suggested that these changes may be related to the combined effect of land-use changes, metal mining impacts and changes in flood frequency and magnitude that occurred at this time within the upper Severn basin. In contrast, the particle size characteristics of post Late Devensian/Early Holocene units from Tanat,Vyrnwy palaeochannels were random with no discernible age,size patterns. It is suggested that the non-systematic grain size distribution may be due to the steeper valley gradients of the Tanat,Vyrnwy system (and by inference higher stream powers) and its relatively narrow valley form enabling more effective coupling between coarser outwash deposits found on and at the edges of hillslopes and the valley floor. Although the two study reaches have undergone comparable environmental change during the Holocene and lie in the piedmont zone of their catchments, palaeochannel units of the same age possess distinctly different characteristics. Intrinsic reach-scale geomorphic factors would appear to preclude the uniform application of particle size characteristics to determine alluvial response to environmental change. Consequently, care needs to be applied to the use of such data for environmental discrimination because the phenomenon of equifinality means that a specific set of sediment characteristics is not necessarily exclusive to specific fluvial environments in either space or time. Copyright © 2001 John Wiley & Sons, Ltd. [source]

    First-order reversal curve diagrams and thermal relaxation effects in magnetic particles

    Christopher R. Pike
    Summary We have recently developed a technique for characterizing the magnetic components within natural particle assemblages. This technique is based on the transformation of magnetization data from first-order reversal curves (FORCs) into contour plots of a 2-D distribution function (FORC diagrams). FORC diagrams are useful for obtaining information about switching fields and interactions in magnetic particle systems. Here, we examine experimental data and a theoretical model in order to provide a rigorous framework for interpreting FORC diagrams for samples that contain superparamagnetic particles. We have found four distinct manifestations of thermal relaxation on FORC diagrams. First, thermal relaxation will shift the FORC distribution to lower coercivities. Second, at intermediate temperatures, thermal relaxation can generate a secondary peak about the origin of a FORC diagram. This secondary peak indicates that part of a single-domain particle assemblage has become superparamagnetic. At high enough temperatures, the primary peak of the FORC distribution will be located about the origin of a FORC diagram. Third, thermal relaxation can produce a small, but systematic, upward shift of a FORC distribution. Fourth, thermal relaxation will produce contours that lie near and parallel to the vertical axis in the lower quadrant of a FORC diagram. These manifestations make FORC diagrams a powerful tool for studying the effects of thermal relaxation (superparamagnetism) in bulk natural samples, particularly when the samples contain mixed magnetic particle assemblages. [source]

    A Computational Study of the Sub-monolayer Growth of Pentacene

    D. Choudhary
    Abstract A computational study of organic thin-film growth using a combination of ab,initio based energy calculations and kinetic Monte Carlo (KMC) simulations is provided. A lattice-based KMC model is used in which binding energies determine the relative rates of diffusion of the molecules. This KMC approach is used to present "landscapes" or "maps" that illustrate the possible structural outcomes of growing a thin film of small organic molecules, represented as a two-site dimer, on a substrate in which the strength of organic,substrate interactions is allowed to vary. KMC provides a mesoscopic-scale view of sub-monolayer deposition of organic thin films on model substrates, mapped out as a function of the flux of depositing molecules and the temperature of the substrate. The morphology of the crystalline thin films is shown to be a strong function of the molecule,molecule and molecule,substrate interactions. A rich variety of maps is shown to occur in which the small organic molecules either stand up or lie down in a variety of different patterns depending on the nature of the binding to the surface. In this way, it is possible to suggest how to tailor the substrate or the small organic molecule in order to create a desired growth habit. In order to demonstrate how this set of allowable maps is reduced in the case where the set of energy barriers between substrate and organic molecule are reliably known, we have used Gaussian,98 calculations to establish binding energies for the weak van der Waals interactions between a),pairs of pentacene molecules as a function of orientation and b),pentacene and two substrates, silicon surfaces passivated with cyclopentene molecules and a crystalline model of silicon dioxide. The critical nucleation size and the mode of diffusion of this idealized two-site dimer model for pentacene molecules are found to be in good agreement with experimental data. [source]

    Voices in court: lawyers' or litigants'?

    HISTORICAL RESEARCH, Issue 186 2001
    Joanne Bailey
    Written records of litigation lie at the heart of numerous studies of English society and culture. Although some documents appear to demonstrate individuality, historians advise that they be used cautiously since the words of litigants and deponents were filtered through the legal profession. This article uncovers the process of mediation by exploring the interaction between litigants and their legal advisers, using correspondence received by church court proctors. It reveals that some parties had an active role in their litigation and, crucially, that their own motives could obscure the reality underlying their lawsuits as much as the legal process. [source]

    Telling More: Lies, Secrets, and History

    HISTORY AND THEORY, Issue 4 2000
    Luise White
    This essay argues that secrets and lies are not forms of withholding information but forms by which information is valorized. Lies are constructed: what is to be lied about, what a lie is to consist of, how it is to be told, and whom it is to be told to, all reveal a social imaginary about who thinks what and what constitutes credibility. Secrets are negotiated: continual decisions about whom to tell, how much to tell, and whom not to tell describe social worlds, and the shape and weight of interactions therein. All of this makes lies and secrets extraordinarily rich historical sources. We might not see the truth distorted by a lie or the truth hidden by a secret, but we see the ideas andimaginings by which people disclose what should not be made public, and how they should carry out concealing one narrative with another. Such insights involve a step back from the project of social history, in which an inclusive social narrative is based on experience and individuals' ability to report it with some reliability, and suggests that historians need to look at social imaginings as ways to understand the ideas and concerns about which people lie and with which people construct new narratives that are not true. The study of secrets, however, links the study of social imaginings with the project of social history, as the valorization of information that results in the continual negotiation and renegotiation of secrets shows individuals and publics imagining the experiences labeled as secret because of the imagined power of a specific version of events. [source]

    The Prevalence of Lying in America: Three Studies of Self-Reported Lies

    Kim B. Serota
    This study addresses the frequency and the distribution of reported lying in the adult population. A national survey asked 1,000 U.S. adults to report the number of lies told in a 24-hour period. Sixty percent of subjects report telling no lies at all, and almost half of all lies are told by only 5% of subjects; thus, prevalence varies widely and most reported lies are told by a few prolific liars. The pattern is replicated in a reanalysis of previously published research and with a student sample. Substantial individual differences in lying behavior have implications for the generality of truth,lie base rates in deception detection experiments. Explanations concerning the nature of lying and methods for detecting lies need to account for this variation. L'importance du mensonge aux États-Unis : trois études de mensonges auto-déclarés Kim B. Serota, Timothy R. Levine, Franklin J. Boster Cette étude aborde la fréquence et la distribution des mensonges déclarés par la population adulte. Un sondage national a demandéŕ 1 000 adultes américains de déclarer le nombre de mensonges racontés dans une période de 24 heures. 60 % des sujets ont rapporté ne pas avoir dit de mensonge du tout et prčs de la moitié de ces mensonges sont racontés par 5 % des sujets. L'importance des mensonges varie donc largement et la plupart des mensonges déclarés sont formulés par un petit nombre de menteurs prolifiques. Cette tendance se retrouve également dans une nouvelle analyse de recherches déjŕ publiées et dans l'échantillon étudiant. Des différences individuelles importantes dans les comportements mensongers ont également des conséquences pour la généralité d'un taux de référence vérité,mensonge dans les expériences de détection de la tromperie. Les explications concernant la nature du mensonge et les méthodes de détection de mensonges doivent prendre en compte cette variation. Mots clés : tromperie, mensonge, différences individuelles The Prevalence of Lying in America: Three Studies of Self-Reported Lies Research Question: This study addresses the frequency and the distribution of reported lying in the adult population. Significance: In the deception literature, consensus is that most people lie on a daily basis. Yet this view is founded on very little empirical evidence. This research tests the question of lying prevalence. Method: Survey research techniques and descriptive analysis are used to establish base rates and frequency distributions for reported lying behavior. Data source: A national survey asked 1,000 U.S. adults to report the number of lies told in a 24 hour period. Cross-validation is provided by re-analysis of previously reported diary and experimental data and by replication using a sample of 225 students. Findings: The oft-repeated average (arithmetic mean) of one to two lies per day is replicated but the study finds the distribution is highly skewed. On a typical day, 60% of subjects report telling no lies at all, and almost half or all lies are told by only 5% of subjects; thus, prevalence varies widely and most reported lies are told by a few prolific liars. The pattern is replicated in the re-analysis of previously published research and with the student sample. Implications: The findings of a highly skewed distribution render the average number of lies per day misleading. Substantial individual differences in lying behavior also have implications for the generality of truth-lie base-rates in deception detection experiments. Explanations concerning the nature of lying and methods for detecting lies need to account for this variation. Keywords: deception, lies, lying, communication, individual differences Die Prävalenz von Lügen in Amerika. Drei Studien zu selbstberichteten Lügen Forschungsfrage: Diese Studie untersucht die Häufigkeit und Verteilung von Lügen in der erwachsenen Bevölkerung. Zentralität: In der Literatur zu Täuschung besteht Konsens darüber, dass Menschen täglich Lügen. Allerdings basiert diese Feststellung auf wenigen empirischen Daten. Diese Untersuchung testet die Frage nach der Prävalenz von Lügen. Methode: Umfrage und beschreibende Analyse wurden angewandt, um eine Basisrate und Häufigkeitsdistribution für selbstberichtetes Lügenverhalten zu gewinnen. Datenquelle: In einer nationalen Umfrage wurden 1.000 US-amerikanische Erwachsene zur Zahl der Lügen befragt, die sie in 24 Stunden erzählten. Validiert wurden diese Aussagen durch eine erneute Analyse von bereits dokumentierten Tagebuchdaten und Experimentaldaten und durch die Replikation mit einer Stichprobe von 225 Studierenden. Ergebnisse: Der oft wiederholte Durchschnitt (arithmetische Mittel) von ein bis zwei Lügen pro Tag wurde in der Studie repliziert, allerdings zeigte sich auch, dass diese Verteilung schief ist. 60% der Befragten gaben an, an einem typischen Tag keine Lügen zu erzählen, fast die Hälfte aller Lügen wird von nur 5% der Befragten erzählt; die Prävalenz variiert stark und die meisten der berichteten Lügen werden durch wenige produktive Lügner erzählt. Dieses Muster wurde bei einer erneuten Analyse von vorher publizierten Daten und in der Studentenstichprobe repliziert. Implikationen: Die Ergebnisse dieser stark schiefen Verteilung zeigen, dass die durchschnittliche Zahl von Lügen pro Tag irreführend ist. Substantielle individuelle Unterschiede im Lügenverhalten haben Implikationen für die Verallgemeinerbarkeit von Wahrheit-Lüge-Basisraten in Täuschungserfassungs-Experimenten. Erklärungen zur Natur von Lügen und Methoden zur Erfassung von Lügen müssen diese Variation bedenken. Schlüsselworte: Täuschung, Lüge, Lügen, Kommunikation, individuelle Unterschiede La Prevalencia de la Mentira en América: Tres Estudios de Auto-reportes de Mentiras Kim B. Serota, Timothy R. Levine, Franklin J. Boster Michigan State University The authors thank Deborah Kashy Resumen Este estudio trata sobre la frecuencia y la distribución de los reportes de las mentiras de la población adulta. Una encuesta nacional preguntó a 1,000 adultos Estadounidenses que reporten el número de mentiras contadas en un período de 24-horas. 60% de los sujetos reportaron que no dicen mentiras para nada, y casi la mitad son contadas por solo un 5% de los sujetos; así, la prevalencia varía enormemente y muchos reportaron que las mentiras son contadas por pocos mentirosos prolíficos. La pauta es replicada en el re-análisis de investigación previamente publicada y con una muestra de estudiantes. Las diferencias individuales sustanciales en el comportamiento mentiroso tienen implicaciones también para la generalidad del índice basado en la verdad-mentira en los experimentos de detección de decepción. Las explicaciones concernientes a la naturaleza de la mentira y los métodos de detección de mentiras necesitan responder a esta variación. Palabras Claves: decepción, mentiras, mentir, comunicación, diferencias individuales [source]

    Dispersal and migration of juvenile African Black Oystercatchers Haematopus moquini

    IBIS, Issue 3 2003
    Philip A. R. Hockey
    African Black Oystercatchers Haematopus moquini are sedentary as adults. However, colour-ringing of more than 700 juveniles has revealed complex post-fledging movements that vary geographically. Young from the western part of the breeding range either remain within 150 km of their natal site or migrate 1500,2000 km to one of five discrete nursery areas on the Namib Desert coast of central and northern Namibia, and southern Angola. These nurseries all lie north of the species' breeding range. We calculate that 36,46% of all juveniles born in South Africa migrate to nurseries. Birds return to their natal sites from nurseries at 2,3 years old, but never migrate again. Juveniles from the eastern part of the range undertake ,diffusion dispersal', regularly up to 1000 km, but these journeys mostly end within the breeding range, where there are no nurseries. Very few eastern birds reach nurseries. There is no evidence that movements of western birds are density-dependent responses to hatching date, but long-distance migrants are significantly heavier as chicks than are short-distance dispersers. We hypothesize that a genetic basis exists to these movements, possibly triggered by body condition, that could account not only for the highly dichotomous behaviour of western birds, but also for the intermediate behaviour of eastern birds. [source]

    Kinetics of the thermal isomerization of 1,1,2,2-tetramethylcyclopropane

    David K. Lewis
    Reaction rates for the structural isomerization of 1,1,2,2-tetramethylcyclopropane to 2,4-dimethyl-2-pentene have been measured over a wide temperature range, 672,750 K in a static reactor and 1000,1120 K in a single-pulse shock tube. The combined data from the two temperature regions give Arrhenius parameters Ea=64.7 (±0.5) kcal/mol and log10(A, s,1) = 15.47 (±0.13). These values lie at the upper end of the ranges of Ea and log A values (62.2,64.7 kcal/mol and 14.82,15.55, respectively) obtained from three previous experimental studies, each of which covered a narrower temperature range. The previously noted trend toward lower Ea values for structural isomerization of methylcyclopropanes as methyl substitution increases extends only through the dimethylcyclopropanes (1,1- and 1,2-); Ea then appears to increase with further methyl substitution. In contrast, the pre-exponential factors for isomerization of cyclopropane and all of the methylcyclopropanes through tetramethylcyclopropane lie within ±0.3 of log10(A, s,1) = 15.2 and show no particular trend with increasing substitution. © 2006 Wiley Periodicals, Inc. Int J Chem Kinet 38: 483,488, 2006 [source]

    Tourism demand modelling: some issues regarding unit roots, co-integration and diagnostic tests

    Paresh Kumar Narayan
    Abstract This paper investigates the all important issue of diagnostic tests, including unit roots and cointegration, in the tourism demand modelling literature. The origins of this study lie in the apparent lack in the tourism economics literature of detail concerning the diagnostic test aspect. Study of this deficiency has suggested that previous literature on tourism demand modelling may be divided into two categories: the pre-1995 and post-1995 studies. It was found that the pre-1995 and some post-1995 studies have ignored unit root tests and co-integration and, hence, are vulnerable to the so-called ,spurious regression' problem. In highlighting the key diagnostic tests reported by post-1995 studies, this paper contends that there is no need to report the autoregressive conditional heteroskedasticity (ARCH) test, which is applicable only to financial market analysis where the dependent variable is return on an asset. More generally, heteroskedasticity is not seen as a problem in time-series data. However, the reporting of a greater than necessary range of diagnostic tests,,,some of which do not have any theoretical justification with regard to tourism demand analysis,,,does not diminish the precision of the results or the model. This paper should appeal to scholars involved in tourism demand modelling. Copyright © 2003 John Wiley & Sons, Ltd. [source]