177 research outputs found

    On Convergence of the Inexact Rayleigh Quotient Iteration with the Lanczos Method Used for Solving Linear Systems

    Full text link
    For the Hermitian inexact Rayleigh quotient iteration (RQI), the author has established new local general convergence results, independent of iterative solvers for inner linear systems. The theory shows that the method locally converges quadratically under a new condition, called the uniform positiveness condition. In this paper we first consider the local convergence of the inexact RQI with the unpreconditioned Lanczos method for the linear systems. Some attractive properties are derived for the residuals, whose norms are ξk+1\xi_{k+1}'s, of the linear systems obtained by the Lanczos method. Based on them and the new general convergence results, we make a refined analysis and establish new local convergence results. It is proved that the inexact RQI with Lanczos converges quadratically provided that ξk+1ξ\xi_{k+1}\leq\xi with a constant ξ1\xi\geq 1. The method is guaranteed to converge linearly provided that ξk+1\xi_{k+1} is bounded by a small multiple of the reciprocal of the residual norm rk\|r_k\| of the current approximate eigenpair. The results are fundamentally different from the existing convergence results that always require ξk+1<1\xi_{k+1}<1, and they have a strong impact on effective implementations of the method. We extend the new theory to the inexact RQI with a tuned preconditioned Lanczos for the linear systems. Based on the new theory, we can design practical criteria to control ξk+1\xi_{k+1} to achieve quadratic convergence and implement the method more effectively than ever before. Numerical experiments confirm our theory.Comment: 20 pages, 8 figures. arXiv admin note: text overlap with arXiv:0906.223

    Hightly luminescent bismuth complexes: Aggregation induced phosphorescent and polymorphism-dependent emission

    Get PDF
    The search of simple ligand based metal-organic materials exhibiting Aggregation Induced Emission (AIE) or phosphorescence (AIP) effects and strong luminescence in the solid state is of high interest. Recently, we demonstrated that bipyridine derivatives consisting of one pyridinium cycle (acting as electron acceptor) and one pyridyl (N-methyl-4,4’-bipyridinium)1 or one pyridyl-N-oxide part (N-R-N’-oxide-4,4’-bipyridinium, R= methyl, H)2 were able to bind bismuth ions, giving complexes with photochromic and average luminescent properties. In this communication, we will report the results of our investigations in the Bi(III)/L systems, where L= bipyridinium based ligands of N-oxide type (N-oxide-4,4’(2,2’)-bipirydinium (bp4mo and bp2mo) and N,N’-dioxide-4,4’-bipyridinium (bp4do)). More recently, we synthesized a 2D CP in which the bp4mo ligand acts as a bridge between two Pb2+ ions,3 but no bismuth complexes or CP based on bp4mo (bp2mo) or bp4do have been mentioned up to now. The impressive solid state Quantum Yields (QY) -up to 85% for (TBA)[BiBr4(bp4mo)]- are obtained for several materials while others are non-luminescent. The three polymorphs α- (QY= 20%), β- and γ-[BiBr3(bp2mo)2] (QY= 0) will be given as examples. These structure-property relationships are assigned to environment rigidity or interactions between ligands in the solid state. A complete study of the luminescent properties (100-300 K range, lifetime, solid state and solution measurements) combined with DFT calculations and the analysis of the crystal structures shows that the lighting phenomenon is of AIP type which is induced by complex (Figure 1)

    Hydrodynamic gene delivery in human skin using a hollow microneedle device

    Get PDF
    Microneedle devices have been proposed as a minimally invasive delivery system for the intradermal administration of nucleic acids, both plasmid DNA (pDNA) and siRNA, to treat localised disease or provide vaccination. Different microneedle types and application methods have been investigated in the laboratory, but limited and irreproducible levels of gene expression have proven to be significant challenges to pre-clinical to clinical progression. This study is the first to explore the potential of a hollow microneedle device for the delivery and subsequent expression of pDNA in human skin. The regulatory approved MicronJet600® (MicronJet hereafter) device was used to deliver reporter plasmids (pCMVβ and pEGFP-N1) into viable excised human skin. Exogenous gene expression was subsequently detected at multiple locations that were distant from the injection site but within the confines of the bleb created by the intradermal bolus. The observed levels of gene expression in the tissue are at least comparable to that achieved by the most invasive microneedle application methods e.g. lateral application of a microneedle. Gene expression was predominantly located in the epidermis, although also evident in the papillary dermis. Optical coherence tomography permitted real time visualisation of the sub-surface skin architecture and, unlike a conventional intradermal injection, MicronJet administration of a 50 μL bolus appears to create multiple superficial microdisruptions in the papillary dermis and epidermis. These were co-localised with expression of the pCMVβ reporter plasmid. We have therefore shown, for the first time, that a hollow microneedle device can facilitate efficient and reproducible gene expression of exogenous naked pDNA in human skin using volumes that are considered to be standard for intradermal administration, and postulate a hydrodynamic effect as the mechanism of gene delivery

    Supramolecular coordination chemistry of aromatic polyoxalamide ligands: A metallosupramolecular approach toward functional magnetic materials

    Get PDF
    The impressive potential of the metallosupramolecular approach in designing new functional magnetic materials constitutes a great scientific challenge for the chemical research community that requires an interdisciplinary collaboration. New fundamental concepts and future applications in nanoscience and nanotechnology will emerge from the study of magnetism as a supramolecular function in metallosupramolecular chemistry. Our recent work on the rich supramolecular coordination chemistry of a novel family of aromatic polyoxalamide (APOXA) ligands with first-row transition metal ions has allowed us to move one step further in the rational design of metallosupramolecular assemblies of increasing structural and magnetic complexity. Thus, we have taken advantage of the new developments of metallosupramolecular chemistry and, in particular, the molecular-programmed self-assembly methods that exploit the coordination preferences of paramagnetic metal ions and suitable designed polytopic ligands. The resulting self-assembled di- and trinuclear metallacyclic complexes with APOXA ligands, either metallacyclophanes or metallacryptands, are indeed ideal model systems for the study of the electron exchange mechanism between paramagnetic metal centers through extended π-conjugated aromatic bridges. So, the influence of different factors such as the topology and conformation of the bridging ligand or the electronic configuration and magnetic anisotropy of the metal ion have been investigated in a systematic way. These oligonuclear metallacyclic complexes can be important in the development of a new class of molecular magnetic devices, such as molecular magnetic wires (MMWs) and switches (MMSs), which are major goals in the field of molecular electronics and spintronics. On the other hand, because of their metal binding capacity through the outer carbonyl-oxygen atoms of the oxamato groups, they can further be used as ligands, referred to as metal–organic ligands (MOLs), toward either coordinatively unsaturated metal complexes or fully solvated metal ions. This well-known “complex-as-ligand” approach affords a wide variety of high-nuclearity metal–organic clusters (MOCs) and high-dimensionality metal–organic polymers (MOPs). The judicious choice of the oligonuclear MOL, ranging from mono- to di- and trinuclear species, has allowed us to control the overall structure and magnetic properties of the final oxamato-bridged multidimensional (nD, n = 0–3) MOCs and MOPs. The intercrossing between short- (nanoscopic) and long-range (macroscopic) magnetic behavior has been investigated in this unique family of oxamato-bridged metallosupramolecular magnetic materials expanding the examples of low-dimensional, single-molecule (SMMs) and single-chain (SCMs) magnets and high-dimensional, open-framework magnets (OFMs), which are brand-new targets in the field of molecular magnetism and materials science

    Designing creative spaces: An experimental examination of the effect of a nature poster on divergent thinking

    Get PDF
    This paper reports the results of an independent samples experiment designed to examine the effects of the presence of a large poster depicting a natural woodland scene on individual performance on two Divergent Thinking tasks. In comparison to the no-poster control condition, the presentation of a large poster depicting a nature scene was found to lead to greater levels of creativity as rated by judges who were blind to the experimental design. The effects of the large poster on Divergent Thinking were found to hold when controlling for Openness-to-Experience and Mood. Exploratory analyses of participant ratings of room characteristics indicated that the mechanism underlying the posters’ effect related to elevated stimulation

    Dependent seniors garment design

    Get PDF
    This paper is part of a PhD research in Textile Engineering at University of Minho and aims to establish an ergonomic pattern design methodology to be used in the construction of garments for elderly women, aged 65 and over, dependent of care. The research was developed with a close contact with four institutions involved in supporting this aged population, located in the cities of Guimaraes (Portugal) and Teresina (Brazil). These clothes should be adequate to their anthropometrics and their special needs, in accordance with important functional factors for the dependency of their caregiver, such as: care for the caregiver and comfort for the user. Questions regarding the functional properties of the materials, the pattern design process, trimmings and the assembling process of the garments are specially considered in the desired comfort levels, in order to provide an adequate handling by facilitating the dressing and undressing tasks, but also to assure the user the needed comfort in all its variables.This work is supported by FEDER funds through the Competitive Factors Operational Program (COMPETE) POCI-01-0145-FEDER-007136 and by national funds through Portuguese Foundation for Science and Technology (FCT), under the project UID/CTM/000264 financed by Science Without Borders/CAPEs.info:eu-repo/semantics/publishedVersio

    Back to the past: the individual and its role in creativity in organisations

    Get PDF
    O objetivo deste texto é realçar o papel do indivíduo na criatividade nas organizações. Esse papel tem sido estranhamente remetido para um plano secundário, à medida que as modernas visões da criatividade a definem, sobretudo, com relação ao contexto em que ocorre. De fato, na perspectiva atual, a criatividade não pode ser entendida sem se considerarem os contextos funcional, relacional e organizacional nos quais está inserido o trabalhador. Tais são as considerações da maior parte dos autores que escreve sobre o tópico, como sejam Amabile (1996), Csikszentmihalyi (1996), ou, mais recentemente, Glăveanu (2010a, 2010b). Essa corrente dominante, com origem no interacionismo psico-social, tem ainda influenciado o desenvolvimento teórico de outros conceitos em psicologia, sociologia, e, na sequência, nas ciências sociais e humanas, e na gestão. Essa supremacia no que concerne a criatividade, tem conduzido os autores a olvidar o papel do indivíduo no processo e no resultado criativos, chegando a retirar-lhe a responsabilidade e o protagonismo pela geração e produção de ideias. Desse modo, no presente texto, recuperam-se os argumentos em favor da centralidade da pessoa na criatividade, defendendo-se que esta tem uma existência isolada de influências externas, e que, como tal, devem relembrar-se as bases individuais da criatividadeThe goal of the current text is to highlight the role of the individual in creativity in organisations. This role has been strangely disregarded in recent years, as modern accounts of creativity have been emphasising the idea that creativity is only defined in context. This main stream argues that creativity is a process that essentially occurs within a functional, relational, and organisational context in which workers are inserted. Key authors defending such a position include the likes of Amabile (1996), Csikszentmihalyi (1996), and, more recently, Glăveanu (2010a, 2010b). This is a vision rooted in the psychosocial interactionist perspective, which has also had a considerable impact in other areas in psychology, sociology, management and other social and human sciences. This supremacy, with regards to creativity, has led many to forget the role of the individual person in the creative process and output, removing their responsibility and protagonism for generating and producing ideas. Hence, the current text intends to bring back to discussion the individual bases of creativity, that people can have an existence isolated from external influences, further defending that the concept can and should be defined out of context, rather than in contextinfo:eu-repo/semantics/publishedVersio

    Business model innovation for eco-efficiency: an empirical study

    Get PDF
    Business model has the potential to create value and capture value for companies, which is critical for their sustainable development [1]. The concept of eco-efficiency can be a useful concept to link an enterprise’s business with sustainable development as well as achieving long-term profits [2,3]. Extant lit- erature reveals that there is a need to study business model innovation and eco- efficiency under one text to achieve a win-win rationale to increase profits while reducing environmental impact [4,5]. This empirical study conducted 8-in-depth case studies with manufacturing companies across UK and China. The author synthesized the cases and concluded the measures of business model innovation for eco-efficiency in five categories, namely (1) Selling of service model, (2) Direct selling model, (3) Collaboration strategy, (4) Whole system design strat- egy, and (5) Technology renovation strategy. The empirical finding suggests the adaptation of strategy and exploitation of the technologies are essential to busi- ness model innovation when manufacturing companies seeking to implement eco-efficiency

    Identificação dos riscos de distúrbios ocupacionais em uma microempresa de confecção: contribuições da terapia ocupacional

    Get PDF
    Occupational disorders are pathologies with cumulative trauma and slow and progressive evolution, linked to occupational activities performed and/or working conditions. Such, based on the increasing number of occupational disorders in the confection branch, this study aims to identify risks of occupational disorders in a small group of seamstresses in the interior of Paraíba, and also point contributions of occupational therapy in view of the well-being these subjects in their work environment, preventing possible illnesses resulting from their work activities affecting performance in their daily occupations. As a means of evaluation we used the body map, pain scale, self-administered questionnaire professional sociodemographic and a observation script of systematic ergonomic direct and indirect, that have been applied/performed with these seamstresses. Data from these instruments were coded for the realization of individual and/or collective orientations of a preventive nature and aiming the well-being of these individuals in their working environment to not affect other occupations that may be significant.Distúrbios ocupacionais são as patologias com traumas cumulativos e de evolução lenta e progressiva, vinculadas às atividades ocupacionais desempenhadas e/ou às condições de trabalho. Assim, tendo como base o crescente aumento de distúrbios ocupacionais no ramo da confecção, o presente estudo visa identificar riscos de distúrbios ocupacionais em um pequeno grupo de costureiras no interior da Paraíba, e também apontar contribuições da Terapia Ocupacional tendo em vista o bem-estar desses sujeitos em seu ambiente de trabalho, evitando possíveis adoecimentos decorrentes de suas atividades laborais que afetem o desempenho em suas ocupações diárias. Como forma de avaliação foi utilizado o mapa corporal, escala de dor, questionário sócio demográfico profissional autoaplicável e um roteiro de observação ergonômico sistemático direto e indireto, que foram aplicados/realizados com as referidas costureiras. Os dados provenientes desses instrumentos foram codificados para a realização das orientações individuais e/ou coletivas de cunho preventivo e objetivando o bem-estar desses indivíduos em seu contexto de trabalho para não afetar outras ocupações que lhes sejam significativas
    corecore