Nonlinear Schrodinger equation with chaotic, random, and nonperiodic nonlinearity

In this Letter we deal with a nonlinear Schrodinger equation with chaotic, random, and nonperiodic cubic nonlinearity. Our goal is to study the soliton evolution, with the strength of the nonlinearity perturbed in the space and time coordinates and to check its robustness under these conditions. Here we show that the chaotic perturbation is more effective in destroying the soliton behavior, when compared with random or nonperiodic perturbation. For a real system, the perturbation can be related to, e.g., impurities in crystalline structures, or coupling to a thermal reservoir which, on the average, enhances the nonlinearity. We also discuss the relevance of such random perturbations to the dynamics of Bose-Einstein condensates and their collective excitations and transport. (C) 2010 Elsevier B.V. All rights reserved.

Cloning, expression, purification and characterization of recombinant glutathione-S-transferase from Xylella fastidiosa

Xylella fastidiosa is an important pathogen bacterium transmitted by xylem-feedings leafhoppers that colonizes the xylem of plants and causes diseases on several important crops including citrus variegated chlorosis (CVC) in orange and lime trees. Glutathione-S-transferases (GST) form a group of multifunctional isoenzymes that catalyzes both glutathione (GSH)-dependent conjugation and reduction reactions involved in the cellular detoxification of xenobiotic and endobiotic compounds. GSTs are the major detoxification enzymes found in the intracellular space and mainly in the cytosol from prokaryotes to mammals, and may be involved in the regulation of stress-activated signals by suppressing apoptosis signal-regulating kinase 1. In this study, we describe the cloning of the glutathione-S-transferase from X. fastidiosa into pET-28a(+) vector, its expression in Escherichia coli, purification and initial structural characterization. The purification of recombinant xfGST (rxfGST) to near homogeneity was achieved using affinity chromatography and size-exclusion chromatography (SEC). SEC demonstrated that rxfGST is a homodimer in solution. The secondary and tertiary structures of recombinant protein were analyzed by circular dichroism and fluorescence spectroscopy, respectively. The enzyme was assayed for activity and the results taken together indicated that rxfGST is a stable molecule, correctly folded, and highly active. Several members of the GST family have been extensively studied. However, xfGST is part of a less-studied subfamily which yet has not been structurally and biochemically characterized. In addition, these studies should provide a useful basis for future studies and biotechnological approaches of rxfGST. (C) 2008 Elsevier Inc. All rights reserved.

On a formula for the spectral flow and its applications

We consider a continuous path of bounded symmetric Fredholm bilinear forms with arbitrary endpoints on a real Hilbert space, and we prove a formula that gives the spectral flow of the path in terms of the spectral flow of the restriction to a finite codimensional closed subspace. We also discuss the case of restrictions to a continuous path of finite codimensional closed subspaces. As an application of the formula, we introduce the notion of spectral flow for a periodic semi-Riemannian geodesic, and we compute its value in terms of the Maslov index. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Equal Couples in Equal Houses : Cultural perspectives on Swedish solar and bio-pellet heating design

Knowing how to design a heating system that will work mechanically is quite different from knowling how to design a system that users perceive as responsive to their domestic practices and values. In this chapter, social anthropologist Henning argues that the challenge for designers involved in the development or marketing of green buildings with heating systems that are based on renewable sources of energy is to see things from the perspective of those who are supposed to live in these buildings. The chapter focuses on three culture-specific aspects of Swedish households and single-family houses: perceptions of house and home, of private and public space, and of male and female space. Through these three angles, some clues are given as to how design, performance and location of solar and bio-pellet heating systems could be made to resonate with predominant experiences, habits and ways of thinking among both men and women.

Immigration, security and the public debate on US language policy : a critical discourse analysis of language attitudes in the United States of America

The narrative of the United States is of a "nation of immigrants" in which the language shift patterns of earlier ethnolinguistic groups have tended towards linguistic assimilation through English. In recent years, however, changes in the demographic landscape and language maintenance by non-English speaking immigrants, particularly Hispanics, have been perceived as threats and have led to calls for an official English language policy.This thesis aims to contribute to the study of language policy making from a societal security perspective as expressed in attitudes regarding language and identity originating in the daily interaction between language groups. The focus is on the role of language and American identity in relation to immigration. The study takes an interdisciplinary approach combining language policy studies, security theory, and critical discourse analysis. The material consists of articles collected from four newspapers, namely USA Today, The New York Times, Los Angeles Times, and San Francisco Chronicle between April 2006 and December 2007.Two discourse types are evident from the analysis namely Loyalty and Efficiency. The former is mainly marked by concerns of national identity and contains speech acts of security related to language shift, choice and English for unity. Immigrants are represented as dehumanised, and harmful. Immigration is given as sovereignty-related, racial, and as war. The discourse type of Efficiency is mainly instrumental and contains speech acts of security related to cost, provision of services, health and safety, and social mobility. Immigrants are further represented as a labour resource. These discourse types reflect how the construction of the linguistic 'we' is expected to be maintained. Loyalty is triggered by arguments that the collective identity is threatened and is itself used in reproducing the collective 'we' through hegemonic expressions of monolingualism in the public space and semi-public space. The denigration of immigrants is used as a tool for enhancing societal security through solidarity and as a possible justification for the denial of minority rights. Also, although language acquisition patterns still follow the historical trend of language shift, factors indicating cultural separateness such as the appearance of speech communities or the use of minority languages in the public space and semi-public space have led to manifestations of intolerance. Examples of discrimination and prejudice towards minority groups indicate that the perception of worth of a shared language differs from the actual worth of dominant language acquisition for integration purposes. The study further indicates that the efficient working of the free market by using minority languages to sell services or buy labour is perceived as conflicting with nation-building notions since it may create separately functioning sub-communities with a new cultural capital recognised as legitimate competence. The discourse types mainly represent securitising moves constructing existential threats. The perception of threat and ideas of national belonging are primarily based on a zero-sum notion favouring monolingualism. Further, the identity of the immigrant individual is seen as dynamic and adaptable to assimilationist measures whereas the identity of the state and its members are perceived as static. Also, the study shows that debates concerning language status are linked to extra-linguistic matters. To conclude, policy makers in the US need to consider the relationship between four factors, namely societal security based on collective identity, individual/human security, human rights, and a changing linguistic demography, for proposed language intervention measures to be successful.

The Place of Writing in the Poetry of W. B. Yeats and Patrick Kavanagh

Abstract This article addresses the theme of place in the poetry of W. B. Yeats and Patrick Kavanagh, focusing on the concept of place as a physical and psychological entity. The article explores place as a creative force in the work of these two poets, in relation to the act of writing. Seamus Heaney, in his essay “The Sense of Place,” talks about the “history of our sensibilities” that looks to the stable element of the land for continuity: “We are dwellers, we are namers, we are lovers, we make homes and search for our histories” (Heaney 1980: 148-9). Thus, in a physical sense, place is understood as a site in which identity is located and defined, but in a metaphysical sense, place is also an imaginative space that maps the landscapes of the mind. This article compares the different ways in which Yeats and Kavanagh relate to their place of writing, physically and artistically, where place is understood as a physical lived space, and as a liberating site for an exploration of poetic voice, where the poet creates his own country of the mind.

The place of writing in the poetry of W.B Yeats and Patrick Kavanagh

This article addresses the theme of place in the poetry of W. B. Yeats and Patrick Kavanagh, focusing on the concept of place as a physical and psychological entity. The article explores place as a creative force in the work of these two poets, in relation to the act of writing. Seamus Heaney, in his essay “The Sense of Place,” talks about the “history of our sensibilities” that looks to the stable element of the land for continuity: “We are dwellers, we are namers, we are lovers, we make homes and search for our histories” (Heaney 1980: 148-9). Thus, in a physical sense, place is understood as a site in which identity is located and defined, but in a metaphysical sense, place is also an imaginative space that maps the landscapes of the mind. This article compares the different ways in which Yeats and Kavanagh relate to their place of writing, physically and artistically, where place is understood as a physical lived space, and as a liberating site for an exploration of poetic voice, where the poet creates his own country of the mind.

Color detection and segmentation for road and traffic signs

This paper aims to present three new methods for color detection and segmentation of road signs. The images are taken by a digital camera mounted in a car. The RGB images are converted into IHLS color space, and new methods are applied to extract the colors of the road signs under consideration. The methods are tested on hundreds of outdoor images in different light conditions, and they show high robustness. This project is part of the research taking place in Dalarna University / Sweden in the field of the ITS.

Optimization of cable cycles : a trade-off between reliability and cost

This paper elaborates the routing of cable cycle through available routes in a building in order to link a set of devices, in a most reasonable way. Despite of the similarities to other NP-hard routing problems, the only goal is not only to minimize the cost (length of the cycle) but also to increase the reliability of the path (in case of a cable cut) which is assessed by a risk factor. Since there is often a trade-off between the risk and length factors, a criterion for ranking candidates and deciding the most reasonable solution is defined. A set of techniques is proposed to perform an efficient and exact search among candidates. A novel graph is introduced to reduce the search-space, and navigate the search toward feasible and desirable solutions. Moreover, admissible heuristic length estimation helps to early detection of partial cycles which lead to unreasonable solutions. The results show that the method provides solutions which are both technically and financially reasonable. Furthermore, it is proved that the proposed techniques are very efficient in reducing the computational time of the search to a reasonable amount.

Model selection, estimation and forecasting in VAR models with short-run and long-run restrictions

We study the joint determination of the lag length, the dimension of the cointegrating space and the rank of the matrix of short-run parameters of a vector autoregressive (VAR) model using model selection criteria. We consider model selection criteria which have data-dependent penalties for a lack of parsimony, as well as the traditional ones. We suggest a new procedure which is a hybrid of traditional criteria and criteria with data-dependant penalties. In order to compute the fit of each model, we propose an iterative procedure to compute the maximum likelihood estimates of parameters of a VAR model with short-run and long-run restrictions. Our Monte Carlo simulations measure the improvements in forecasting accuracy that can arise from the joint determination of lag-length and rank, relative to the commonly used procedure of selecting the lag-length only and then testing for cointegration.

Model selection, estimation and forecasting in VAR models with short-run and long-run restrictions

We study the joint determination of the lag length, the dimension of the cointegrating space and the rank of the matrix of short-run parameters of a vector autoregressive (VAR) model using model selection criteria. We consider model selection criteria which have data-dependent penalties as well as the traditional ones. We suggest a new two-step model selection procedure which is a hybrid of traditional criteria and criteria with data-dependant penalties and we prove its consistency. Our Monte Carlo simulations measure the improvements in forecasting accuracy that can arise from the joint determination of lag-length and rank using our proposed procedure, relative to an unrestricted VAR or a cointegrated VAR estimated by the commonly used procedure of selecting the lag-length only and then testing for cointegration. Two empirical applications forecasting Brazilian inflation and U.S. macroeconomic aggregates growth rates respectively show the usefulness of the model-selection strategy proposed here. The gains in different measures of forecasting accuracy are substantial, especially for short horizons.

Model selection, estimation and forecasting in VAR models with short-run and long-run restrictions

We study the joint determination of the lag length, the dimension of the cointegrating space and the rank of the matrix of short-run parameters of a vector autoregressive (VAR) model using model selection criteria. We consider model selection criteria which have data-dependent penalties as well as the traditional ones. We suggest a new two-step model selection procedure which is a hybrid of traditional criteria and criteria with data-dependant penalties and we prove its consistency. Our Monte Carlo simulations measure the improvements in forecasting accuracy that can arise from the joint determination of lag-length and rank using our proposed procedure, relative to an unrestricted VAR or a cointegrated VAR estimated by the commonly used procedure of selecting the lag-length only and then testing for cointegration. Two empirical applications forecasting Brazilian in ation and U.S. macroeconomic aggregates growth rates respectively show the usefulness of the model-selection strategy proposed here. The gains in di¤erent measures of forecasting accuracy are substantial, especially for short horizons.

Model selection, estimation and forecasting in VAR models with short-run and long-run restrictions

We study the joint determination of the lag length, the dimension of the cointegrating space and the rank of the matrix of short-run parameters of a vector autoregressive (VAR) model using model selection criteria. We suggest a new two-step model selection procedure which is a hybrid of traditional criteria and criteria with data-dependant penalties and we prove its consistency. A Monte Carlo study explores the finite sample performance of this procedure and evaluates the forecasting accuracy of models selected by this procedure. Two empirical applications confirm the usefulness of the model selection procedure proposed here for forecasting.

Spatio-temporal variation in seed production in three Euphorbia species and the role of animals on seed fate

Comparative studies on the reproductive biology of co-occurring related plant species have provided valuable information for the interpretation of ecological and evolutionary phenomena, with direct application in conservation management of plant populations. The aims of this thesis were to identify the causes of pre-dispersal reproductive losses in three Euphorbia species (the Mediterranean E. characias and the narrow endemics E. pedroi and E. welwitschii) and evaluate the variation of their effects in time, space and between individuals and species. Furthermore, we intended to study elaiosomes’ fatty acid profiles for the three Euphorbia and assess the role played by the elaiosome in ant attraction. Finally, we aimed to identify the major seed dispersal agents for each Euphorbia species in each site and study differences in short term seed fate due to differences in ant behaviour. The results indicated that intact seed production differed significantly between the three Euphorbia, mostly due to differences in cyathia production. Losses to pre-dispersal seed predators were proportionately larger for the endemic species which also suffered higher losses resulting in flower, fruit (in E. welwitschii) and seed abortion (in E. pedroi). The elaiosomes of E. pedroi are poor in fatty acids and for this reason seeds of this species were removed in lower proportion by mutualistic dispersers than those of their congeners, being more prone to seed predation. Two larger ant species – Aphaenogaster senilis and Formica subrufa – were responsible for a larger percentage of removals with seeds being transported at larger distances and being discarded in the vicinity of their nests following elaiosome removal. Our results highlight the role of insect-plant interactions as major determinants of seed survival for the three study plants and call for the need to include more information on insect-plant interactions in plant conservation programmes.

Renal- and calcium-dependent vascular effects of Polybia paulista wasp venom

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)