Theoretical Purposes Research Articles

Covariant hypo-elasticity

The theory of constitutive behavior, with explicit reference to hypo-elastic materials, is addressed with a geometric approach which, following physical arguments, leads to a covariant formulation. The essential role played by a careful distinction between spatial vectors, material-based spatial vectors and material vectors is emphasized. Definite answers to debated issues, such as the proper definition of stress rate, the formulation of integrability conditions, the fulfilment of material frame-indifference, and the task of evaluating the stress state evolution, are given. Simple shear and extension of a specimen of a hypo-elastic material are investigated as applications of the theory. Improper statements and unsound physical responses of hypo-elastic materials are overcome by the covariant theory, thus restoring the proper role to this constitutive model, for both theoretical and computational purposes. ► Spatial and material tensor fields are carefully defined. ► Comparison of material tensors by push is compelling. ► Rates of material tensors are Lie time-derivatives along the motion. ► Elasticity is time-independent and integrable hypo-elasticity. ► Simplest hypo-elasticity is hyper-elastic.

Stepwise superposition approach for the analytical solutions of multi-dimensional contaminant transport in finite- and semi-infinite aquifers

Analytical solutions of contaminant transport in multi-dimensional media are significant for theoretical and practical purposes. However, due to the problems for which the solutions are sought which are complex in most of the cases, most available analytical solutions in multi-dimensional media are not given in their closed forms. Integrals are often included in the solution expressions, which may limit the practitioners to use the solutions. In addition, available multi-dimensional solutions for the third-type sources in bounded media are fairly limited. In this paper, a stepwise superposition approach for obtaining approximate multi-dimensional transport solutions is developed. The approach is based on the condition that the one-dimensional solution along the flow direction is known. The solutions are expressed in their closed forms without integrals. The transport media to the solutions are flexible and can be finite, semi-infinite, or infinite in the transverse directions. The solutions subject to the first- and third-type boundary conditions at the inlet with a distributed source over the domain are obtained. The integrals in some known solutions can also be evaluated by the approach if they can be derived to include known longitudinal integrals with respect to time. The accuracy and efficiency of the solutions proposed in this paper are verified through test problems and calculation examples.

Coming to Terms with Convergence Journalism: Cross-Media as a Theoretical and Analytical Concept

As a result of the emergence of convergent ‘media houses’ at all levels of news journalism, few modern media organizations publish on only one platform. Changing professional practices related to this raise a number of important questions about the relationship between organizational strategies, new technologies, and everyday news journalism. This article addresses these developments from two perspectives, news work and news texts, through the concept of ‘cross-media’. This concept describes communication or production where two or more media platforms are involved in an integrated way. The article argues that in order to be more precise for theoretical and analytical purposes we have to distinguish between cross-media communication, and cross-media production processes. The article concludes by outlining a model that integrates the perspectives of news work and news texts in convergence journalism.

Worlds and Individuals, Possible and Otherwise, by Takashi Yagisawa.

Takashi Yagisawa’s monograph (Worlds) offers a new version of modal realism (Chs 1–8) and subsequent theories of intensional entities, belief contents, and fictional discourse (Chs 9–10). The hinge connecting these two parts of Worlds is the postulation of impossibilia (Ch. 8), justified along the following (familiar) lines: (i) we properly look to quantify over non-actual objects for various theoretical purposes; but, (ii) when we find that quantification restricted to possibilia produces too coarse a grain (conflating belief contents, conflating properties, and failing to discriminate trivial from non-trivial counterfactual conditionals); then, (iii) the remedy is to persist with the method of quantification, but expand ontology to include impossibilia. Yagisawa’s applications of impossibilia are undoubtedly novel in extent and detail, and deserving of serious study. But here I must confine myself to a single observation about the relationship of the applications of impossibilia to the theory of modality that precedes it. It would take some work to pull apart the cases in which Yagisawa relies only on a generic realism about impossibilia (and this seems often to be so) from those in which he relies on distinctive aspects of his own specific theory of impossibility (and of modality in general). And that work lies in wait for the reader who would refuse the underlying theory of modality, but embrace the imaginative applications of impossibilia. Henceforth, I will be concerned only with Yagisawa’s theory of modality.

Revenue management with aircraft reassignment flexibility

A well-studied problem in airline revenue management is the optimal allocation of seat inventory among different fare-classes, given a capacity for the flight and a demand distribution for each class. In practice, capacity on a flight does not have to be fixed; airlines can exercise some flexibility on the supply side by swapping aircraft of different capacities between flights as partial booking information is gathered. This provides the airline with the capability to more effectively match their supply and demand. In this paper, we study the seat inventory control problem considering the aircraft swapping option. For theoretical and practical purposes, we restrict our attention to the class of booking limit policies. Our analytical results demonstrate that booking limits considering the swapping option can be considerably different from those under fixed capacity. We also show that principles on the relationship between the optimal booking limits and demand characteristics (size and risk) developed for the fixed-capacity problem no longer hold when swapping is an option. We develop new principles and insights on how demand characteristics affect the optimal booking limits under the swapping possibility. We also develop an easy to implement heuristic for determining the booking limits under the swapping option and show, through a numerical study, that the heuristic generates revenues close to those under the optimal booking limits. © 2011 Wiley Periodicals, Inc. Naval Research Logistics, 2011

Happiness as a Societal Value.

Executive Overview There has been a tremendous growth in research related to happiness and well-being in recent years, and an influential stream of this research has concerned itself with international differences in happiness. Our goal here is to describe some of the reasons happiness research is important to organizational researchers for both theoretical and practical purposes. We also describe significant methodological issues that should be considered when assessing these relationships at the group level. Finally, we provide suggestions for future research that might productively integrate insights from the organizational literature into happiness studies.

Happiness as a Societal Value

Executive Overview There has been a tremendous growth in research related to happiness and well-being in recent years, and an influential stream of this research has concerned itself with international differences in happiness. Our goal here is to describe some of the reasons happiness research is important to organizational researchers for both theoretical and practical purposes. We also describe significant methodological issues that should be considered when assessing these relationships at the group level. Finally, we provide suggestions for future research that might productively integrate insights from the organizational literature into happiness studies.

Genetic programming with one-point crossover and subtree mutation for effective problem solving and bloat control

Genetic programming (GP) is one of the most widely used paradigms of evolutionary computation due to its ability to automatically synthesize computer programs and mathematical expressions. However, because GP uses a variable length representation, the individuals within the evolving population tend to grow rapidly without a corresponding return in fitness improvement, a phenomenon known as bloat. In this paper, we present a simple bloat control strategy for standard tree-based GP that achieves a one order of magnitude reduction in bloat when compared with standard GP on benchmark tests, and practically eliminates bloat on two real-world problems. Our proposal is to substitute standard subtree crossover with the one-point crossover (OPX) developed by Poli and Langdon (Second online world conference on soft computing in engineering design and manufacturing, Springer, Berlin (1997)), while maintaining all other GP aspects standard, particularly subtree mutation. OPX was proposed for theoretical purposes related to GP schema theorems, however since it curtails exploration during the search it has never achieved widespread use. In our results, on the other hand, we are able to show that OPX can indeed perform an effective search if it is coupled with subtree mutation, thus combining the bloat control capabilities of OPX with the exploration provided by standard mutation.

Spectral clustering based on local linear approximations

In the context of clustering, we assume a generative model where each cluster is the result of sampling points in the neighborhood of an embedded smooth surface; the sample may be contaminated with outliers, which are modeled as points sampled in space away from the clusters. We consider a prototype for a higher-order spectral clustering method based on the residual from a local linear approximation. We obtain theoretical guarantees for this algorithm and show that, in terms of both separation and robustness to outliers, it outperforms the standard spectral clustering algorithm (based on pairwise distances) of Ng, Jordan and Weiss (NIPS '01). The optimal choice for some of the tuning parameters depends on the dimension and thickness of the clusters. We provide estimators that come close enough for our theoretical purposes. We also discuss the cases of clusters of mixed dimensions and of clusters that are generated from smoother surfaces. In our experiments, this algorithm is shown to outperform pairwise spectral clustering on both simulated and real data.

Teorizando o agonismo: crítica a um modelo incompleto

Em trabalhos recentes, Chantal Mouffe promove dois movimentos teóricos concomitantes. Por um lado, critica as teorias deliberativas, sobretudo os enfoques de Rawls e Habermas. Por outro lado, apresenta o modelo agonístico de democracia. A crítica de Mouffe aos deliberacionistas parte do princípio de que tais teóricos buscam a eliminação das relações de poder na política a partir do princípio racional para tomada de decisões. Para Mouffe, a eliminação do poder é uma impossibilidade, uma vez que este fundamenta a própria dimensão ontológica do político. Argumenta-se, contudo, que a alternativa da autora aos modelos deliberativos é insatisfatória, uma vez que sua proposta agonística é tão somente um princípio de ação e não propriamente um modelo teórico político estruturado. O objetivo deste paper é problematizar a proposta teórica de Mouffe, apresentando principalmente suas limitações em relação ao seu desenvolvimento.

25 Year Perspective Recent developments in analysis of high temperature creep and creep fracture behaviour

Over many decades, the creep and creep fracture properties of metals and alloys have commonly been described using power law relationships. However, with this approach, controversies still surround the mechanisms proposed to account for the stress and temperature dependencies of the minimum creep rate and rupture life. Similarly, power law and related expressions do not allow extrapolation of short term data sets to predict the long term properties required for engineering design purposes. For these reasons, over the last 25 years, three UK approaches have evolved, termed the θ projection concept, the hyperbolic tangent method and the Wilshire equations. These methodologies are now applied to results for the aluminium alloy Al 2124, recommending reappraisal of current reliance on power law expressions for theoretical and practical purposes.

Tree expansion in time-dependent perturbation theory

The computational complexity of time-dependent perturbation theory is well known to be largely combinatorial whatever the chosen expansion method and family of parameters (combinatorial sequences, Goldstone and other Feynman-type diagrams, etc.). We show that a very efficient perturbative expansion, both for theoretical and numerical purposes, can be obtained through an original parametrization by trees and generalized iterated integrals. We emphasize above all the simplicity and naturality of the new approach that links perturbation theory with classical and recent results in enumerative and algebraic combinatorics. These tools are applied to the adiabatic approximation and the effective Hamiltonian. We prove perturbatively and nonperturbatively the convergence of Morita’s generalization of the Gell–Mann and Low wave function. We show that summing all the terms associated with the same tree leads to an utter simplification where the sum is simpler than any of its terms. Finally, we recover the Rayleigh-Schrödinger time-independent equation for the wave operator and we give an explicit nonrecursive expression for the term corresponding to an arbitrary tree.

Agente comunitário de saúde: sujeito da prática em saúde bucal em Alagoinhas, Bahia

This study about the work of micro politics was carried out by the Buccal Health Team (ESB) in the Family Health Program (PSF) of Alagoinhas, Bahia State, and has as central theoretical purpose the specific and singular forms in the practice of daily work, using the technologies (hard, light-hard and light). The methodological trajectory is based on the historical-social current in view of a dialectic approach of qualitative nature. The techniques of data collection used were: semi structured interview, observation of the work process and documental analysis. The analysis of the data was oriented by the hermeneutics-dialectics, allowing to compare the different levels of analysis, articulating the theoretical with the empirical evidence. The results reveal that the Family Health Teams are multidisciplinary, but have still not developed an interdisciplinary work, hence occurring juxtaposition of skills. Each unit plans their work process according to the singularities of the social subjects, implementing different characteristics in how to welcome, inform, attend and refer. An effort in changing the work process can be perceived in the perspective of amplified clinic with the health community agent standing out as a social/collective subject.

Time-Tradeoff Sequences for Analyzing Discounting and Time Inconsistency

This paper introduces time-tradeoff (TTO) sequences as a general tool to analyze intertemporal choice. We give several applications. For empirical purposes, we can measure discount functions without requiring any measurement of or assumption about utility. We can quantitatively measure time inconsistencies and simplify their qualitative tests. TTO sequences can be administered and analyzed very easily, using only pencil and paper. For theoretical purposes, we use TTO sequences to axiomatize (quasi-)hyperbolic discount functions. We demonstrate the feasibility of measuring TTO sequences in an experiment, in which we tested the axiomatizations. Our findings suggest rejections of several currently popular discount functions and call for the development of new ones. It is especially desirable that such discount functions can accommodate increasing impatience.

The Many Shades of Communication Research in South Asia

An this paper, I would like to present and discuss communication research and my encounter with it mostly in India for over a quarter of a century. While doing so, I have made a few assumptions and observations about communication research in South Asia and, broadly, Asia. First, it would be important to indicate that in South Asia, communication research cannot be visualised as an integrated whole or it would be difficult to find a body of media and/or communication research that can be referred to as communication research. Communication research, for all theoretical and practical purposes, is divided and continues to be fragmented into conventional, well established, sub-disciplines known for over a century as cinema, radio, television, newspaper and advertising, to mention a few. Now, the Internet and telecommunication have been added to the list. So when one starts looking at communication research in its broad sense, it would be difficult to find any defined body of research methods and techniques at one place.

Recent Research on MBD in JAPAN

Research on multibody dynamics in engineering and science is developing at a high pace in Japan and in the world. These activities provide efficient and powerful solution tools for solving complicated dynamic problems with control via theoretical or high performance in-house and/or general purpose computer programs in academic and industrial fields. Thus, advancement of research is an important index for measuring competitiveness in education and industry in terms of “dynamics and control”. The aim of this paper is to present an overview of the various research activities of multibody dynamics in Japan.

FUNGI IN THE MARINE ENVIRONMENT

The review of published data on fungi as the components of biota of the seas and oceans is presented. The distribution of fungi in different biogeographical regions and biotopes is considered. The importance of depth, temperature and water salinity, types of bottom sediments for the species composition and number of fungal propagules is revealed. The role of saprophytic, parasitic, symbiotic and opportunistic fungi in marine ecosystems as well as the relations of marine fungi and animals are shown. Some perspective lines of further investigations of marine fungi for theoretical and practical purposes are analysed.

PRODUCTIVE MUTATIONS INDUCED IN BARLEY BY IONIZING RADIATIONS AND CHEMICAL MUTAGENS

HereditasVolume 50, Issue 2-3 p. 211-262 Open Access PRODUCTIVE MUTATIONS INDUCED IN BARLEY BY IONIZING RADIATIONS AND CHEMICAL MUTAGENS ÅKE GUSTAFSSON, ÅKE GUSTAFSSON DEPARTMENT OF FOREST GENETICS, STOCKHOLM 50 THE SWEDISH SEED ASSOCIATION, SVALÖFSearch for more papers by this author ÅKE GUSTAFSSON, ÅKE GUSTAFSSON DEPARTMENT OF FOREST GENETICS, STOCKHOLM 50 THE SWEDISH SEED ASSOCIATION, SVALÖFSearch for more papers by this author First published: December 1963 https://doi.org/10.1111/j.1601-5223.1963.tb01907.xCitations: 13AboutPDF ToolsExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume50, Issue2-3December 1963Pages 211-262 ReferencesRelatedInformation

“Rally Round the Flag” Events for Presidential Approval Research

Since Mueller's [Mueller, J., 1970. Presidential popularity from Truman to Johnson. The American Political Science Review 64 (1), 18–34.] pioneering study, students of presidential approval ratings have agreed that major events affect these ratings. Despite this consensus, there is wide divergence in the ways that scholars have selected events for inclusion in models of approval ratings. This inconsistency inhibits direct comparisons across studies and raises the possibility that results are contingent on those selection criteria. Thus, what we have learned about the impact of various factors that may affect approval may depend on the details of selection criteria. Practically, scholars analyzing presidential approval ratings for any theoretical purpose must construct a list of events themselves, which takes considerable time. We propose a set of selection criteria and construct a list of events from 1953 to 2006 that scholars can employ. We also demonstrate that the list of events generates empirical results that comport with extant findings in the presidential approval literature.

THE ‘HAUNTED’ SHOSTAKOVICH AND THE CO-PRESENCE OF BACH

My theoretical purpose is to distinguish between musical allusions and musical co-presences. A musical allusion is usually a citation of a melody or phrase from a work by a predecessor. In Shostakovich's Fifteenth Symphony, for example, references to Rossini's William Tell and to Wagner's Ring have tantalized listeners and provoked speculation on what these allusions could mean. In general, Shostakovich's music is notable for containing numerous allusions, often ironic, to previous composers. By contrast, Shostakovich's 24 Preludes and Fugues and the Eighth String Quartet show more than mere allusions to Bach: the very methods and forms of the Baroque master are incorporated into the later composer's works, as if Bach were a co-creator with Shostakovich; and those methods and forms are not employed ironically. That is to say, the music of Bach has a special significance for Shostakovich, a presence that goes beyond any topical value.