Theoretical Purposes Research Articles

Exact second-order structure-function relationships

Equations that follow from the Navier–Stokes equation and incompressibility but with no other approximations are ‘exact’. Exact equations relating second- and third- order structure functions are studied, as is an exact incompressibility condition on the second-order velocity structure function. Opportunities for investigations using these equations are discussed. Precisely defined averaging operations are required to obtain exact averaged equations. Ensemble, temporal and spatial averages are all considered because they produce different statistical equations and because they apply to theoretical purposes, experiment and numerical simulation of turbulence. Particularly simple exact equations are obtained for the following cases: (i) the trace of the structure functions, (ii) DNS that has periodic boundary conditions, and (iii) an average over a sphere in r-space. Case (iii) introduces the average over orientations of r into the structure-function equations. The energy dissipation rate ε appears in the exact trace equation without averaging, whereas in previous formulations ε appears after averaging and use of local isotropy. The trace mitigates the effect of anisotropy in the equations, thereby revealing that the trace of the third-order structure function is expected to be superior for quantifying asymptotic scaling laws. The orientation average has the same property.

Structure-function equations for scalars

An exact equation is obtained which relates the products of two-point differences of a scalar quantity and those differences with the difference of velocity and other quantities. The averages of such products are structure functions. Equations that follow from the scalar equation but with no other approximations are called “exact” here. Exact equations for structure functions are obtained. Ensemble, temporal, and spatial averages are all considered because each one produces different statistical equations from the others and because they differ in application to theoretical purposes, experiment, and numerical simulation of turbulence. The midpoint and the difference of the two points at which the hydrodynamic quantities are obtained are X and r, respectively. Use of X and r as independent variables combined with Reynolds decomposition reveals quantifiable effects of inhomogeneity and large-scale structures. Exact equations obtained by averaging over a sphere in r space have a particularly simple form. The case of a numerical simulation that has periodic boundary conditions leads to particularly simple equations. For the case of grid-generated wind-tunnel turbulence, approximate equations are derived relating structure functions of fluctuations. Applications of the equations to experiments and direct numerical simulation are discussed.

MORPHOLOGICAL, PRODUCTION BIOLOGICAL AND CHEMICAL DIVERSITY OF ST. JOHN'S WORT (HYPERICUM PERFORATUM L.)

MORPHOLOGICAL, PRODUCTION BIOLOGICAL AND CHEMICAL DIVERSITY OF ST. JOHN'S WORT (HYPERICUM PERFORATUM L.)

Nomadic movement in tropical toads

Dispersal is a critical aspect of the biology of most organisms, but movement patterns are poorly known for most animals. Knowledge of movement patterns allows biologists to construct realistic spatial models, either for theoretical or empirical purposes. Cane toads (Bufo marinus) have high survival rates (30–70% per annum in Australia), but very low recapture rates over long periods in marking studies, suggesting that they may be nomadic. Here we model the movement patterns of cane toads to determine whether they move nomadically. Using radiotracking, we quantified the movements of 64 cane toads, at two widely separated locations in northern Australia. We established that toad movements were indeed nomadic by comparing real movements with those generated by an individual‐based, correlated random walk model that selected randomly from empirical distributions of movement parameters. In the wet season, at both locations, real movements were similar to those generated by the model, indicating that toads moved nomadically during this time of year. During the dry season at both locations, toads used a smaller area and travelled less straight paths than predicted by the model. Nomadic movements were more common and extensive during the wet season, although some individuals moved nomadically at all times of year. To determine whether the model provided a good description of toad movements over the long term, we compared observed disappearance rates from a mark‐recapture study conducted in one of our study sites, with disappearance rates predicted by the model. There was good agreement between these two methods of measuring toad movements. Previous studies indicated that food availability was lowest and desiccation risk and predation risk were highest in the dry season, suggesting that nomadic movement of toads is most extensive when the costs of movement due to desiccation, predation and energy limitation are lowest.

Workplace Discrimination, Good Cause, and Color Blindness

By general consensus, employers are morally obligated to not discriminate. But do we really know what unethical discrimination in the workplace is? If we try to explain exactly what it is, we may soon discover that we are not as clear about it as we had thought. Let us consider what we may call the Bank Teller case. In a small town in the year 1925, one of the town’s two banks, State Trust, has a teller who is a black person. Although this teller’s job performance is fine, the bigoted townspeople are expressing their disapproval of having a black person handling their money by taking their business to the town’s other bank. This is causing a slow, but continuous loss of business for State Trust, which, although not threatening to the bank’s existence, is nevertheless responsible for a serious, steady drain upon its profits. For the purpose of preventing any further drain upon profits, State Trust, with expressions of genuine regret, terminates the teller’s employment. Does terminating his employment constitute unethical, workplace discrimination? Let us also consider affirmative action, in the form of preferential treatment for minorities and women. Is it, as its opponents claim, simply another form of unethical discrimination? If not, exactly why not? If questions such as these are to be answered adequately, we need an exact account of what unethical, workplace discrimination really is. Since our concern is with morality, not law, we should suspend judgment about the legal status of any hypothetical cases we will consider, and concentrate only on their moral status independent of any law. For practical purposes, their legal status is important. But for theoretical purposes, their moral status is even more important since, ultimately, law should be guided by justifiable morality.

Parameters, prediction, post-normal science and the precautionary principle—a roadmap for modelling for decision-making

In the wake of the ‘discovery of complexity’, dynamical simulation models have become widespread, guiding human interaction with complex systems, e.g. in ecosystem management, environmental decision-making and risk assessment. Any model establishes a reading frame for ecological phenomena or systems, determining the parameters that are assumed to be adequate for the encoding of ecological phenomena. Departing from a definition of observation as the operation of distinguishing and designating, and as the application of certain distinctions to complex phenomena, we analyze the construction of reading frames. As dynamical systems are the prevalent paradigm and reading frame for ecosystems, we describe the sequence of distinctions and selections by which scientists encode ecosystems into formal, dynamical system representations. Major shortcomings of the dynamical system paradigm are highlighted: dynamical systems are conceptually closed systems requiring a fixed set of a priori defined parameters, part of which are parameters of convenience satisfying mathematical needs and part of which are residual parameters that account for noise and system background. Ecosystems, in contrast, are conceived as conceptually open, self-modifying systems, which constantly (‘on-line’) produce novelty and new parameters and which cannot be severed from their environment. Although calibration may adapt models to data sets of the past, it does not assure predictive capacity nor validity. While models serve heuristic and theoretical functions and may outline the space of possible behaviour, they may be deficient instruments for the reduction of uncertainty as to future system behaviour. Different forms of uncertainty are at the heart of environmental decision-making, among them epistemic uncertainty, which arises when the normal, disciplinary forms of uncertainty reduction fail and which leads to debate on adequate ways of coping with uncertainty. Epistemic uncertainty in environmental issues may call for a different type of science that differs from normal, positivist science. Such post-normal science is transdisciplinary, participative and context-sensitive in that it aims at the production of knowledge for concrete, real-world problems. New forms of knowledge production such as the concept of post-normal science in conjunction with the precautionary principle challenge the established authority of science and may lead to an institutional split of science into an academic branch and a managerial, public policy branch. Correspondingly, modelling for theoretical scientific purposes and modelling for decision-making may follow separate paths. Modelling for decision-making may have to take into account requests for transparency and participation (‘deliberation frames analysis’) and the validity of model products will be judged according to their capacity of providing context-sensitive knowledge for specific decision problems.

Introduction to Experimental Nonlinear Dynamics

Of the several archetypal equations such as those of Lorenz, H�non, R�ssler etc, it is the so-called Duffing equation, and especially its double-well form, that constitutes the backbone of this book. L N Virgin presents basic linear behaviour and useful concepts that are necessary for studying nonlinear behaviour (e.g. Poincar� sections, spectral analysis). Then the paradigm of the Duffing equation is introduced within the framework of nonlinear structural dynamics. An analogy is developed between the dynamics of a continuous beam and the behaviour of a point mass sliding on a curve. This latter system is carefully described from a mathematical point of view so that the theoretical bases for construction of experiments and a primary analysis of results are posed. Several experimental models and devices are derived from previous systems (cart movement, Scotch-Yorke forcing, `impact' experiments with cart). Worthwhile numerical values are given that correspond to the dimensions and properties of materials in experimental settings. Theoretical and experimental frameworks are generally clearly explained. The author can provide analytical and/or numerical results together with experimental results. The pleasant presentation of the field of nonlinear oscillations and chaos is continually reinforced by the good agreement that is obtained and shown between numerical and experimental results, even for global dynamics with chaos (e.g. attractors via Poincar� maps, basins of attraction). This book will surely be of great interest to students, engineers and researchers involved in the field of nonlinear dynamics. To conclude, let us say that the main disadvantage of this book is that experimental devices are not sold with it! Fortunately, so that one can neglect this `defect', a website address is available: readers can see movies of the most significant experiments that illustrate the theoretical purpose of this most interesting book. C-H Lamarque

A numerical strategy for efficient modeling of the equatorial wave guide

Convection in the tropics is observed to involve a wide-ranging hierarchy of scales from a few kilometers to the planetary scales and also has a profound impact on short-term climate. The mechanisms responsible for this behavior present a major unsolved problem. A promising emerging approach to address these issues is cloud-resolving modeling. Here a family of numerical models is introduced specifically to model the feedback of small-scale deep convection on tropical planetary waves and tropical circulation in a highly efficient manner compatible with the approach through cloud-resolving modeling. Such a procedure is also useful for theoretical purposes. The basic idea in the approach is to use low-order truncation in the meriodonal direction through Gauss--Hermite quadrature projected onto a simple discrete radiation condition. In this fashion, the cloud-resolving modeling of equatorially trapped planetary waves reduces to the solution of a small number of purely zonal two-dimensional wave systems along a few judiciously chosen meriodonal layers that are coupled only by some additional source terms. The approach is analyzed in detail with full mathematical rigor for linearized equatorial primitive equations with source terms.

JOB SATISFACTION AND COMMITMENT OF TWO-YEAR COLLEGE PART-TIME FACULTY

One of the more significant trends in higher education has been the recent increase in dependence on part-time faculty members. Community colleges, more than any other sector of higher education, have been affected by this trend. However, few scholars and policy makers have made systematic studies to identify whether these individuals are satisfied with their roles, responsibilities, and rewards. The purpose of this investigation was to use nationally representative data to comprehensively study the job satisfaction and commitment of two-year college part-time faculty members. In doing so, this study provided richer definitions of job satisfaction and commitment that for practical and theoretical purposes better capture the multidimensionality of the psychological constructs of job satisfaction and commitment.

Preâmbulos das Constituições do Brasil

The State exerts primordial influence in the life of all the people and all the human groups. This is a fact of our time, independent of the will of each one, not having anyone, rich or poor, powerful or humble person, who can be total free of the influence of the State. For this reason, the State is subject of extraordinary relevance in all studies and researches, of character theoretical or aiming practical purpose, concerning to the human behaviors. Thus, also, for the taking of the decisions of bigger importance, of political, economic or social character, it is absolutely necessary to consider the State, as to take care of to its determination or to deduct themselves from them, as to use it to gain benefits or to defend of threats or aggressions of many species. For all these reasons, the concern with the evolution of the State is constant, with the paper that it will be able to represent in the history of the Humanity, in next or remote future. Thus being, this work is based on historical experience and considering the actual circumstances, leading in account the resultant data of studies and research in multiple scientific areas which occupy of the human behaviors, are an effort of prediction about the future of the State. It is not a proposal for the future nor an abstract speculation, but, differently of this, it is an attempt of prediction of the future of the State with scientific bases

Knocking on Doors: On Constructing Culture

This reflective piece employs a layered text format and uses data from a pilot study on parents’ conceptualizations of parental involvement in schools to think theoretically about such issues as access, voice, and representation in interpretive research. As the researcher engages with the process of selecting participants for her research, a different kind of understanding of cultural access emerges. Access is eventually understood as not being solely a methodological tool for theoretical sampling purposes but an ontological framework that shapes the inquiry process from beginning to end. This researcher eventually adopts a narrative ontology that necessitates the participants’ active involvement in interpreting the meanings that the participants’ stories have on their lives.

Transmyocardial laser revascularization with excimer laser: clinical results at 1 year

Background. Transmyocardial laser revascularization, a new strategy for the treatment of diffuse ischemic heart disease, uses laser technology for the theoretical purpose of forming transmyocardial channels in the heart to increase perfusion to ischemic zones. This report summarizes our initial clinical experience with the procedure. Methods. Excimer transmyocardial laser revascularization was performed in a reversibly ischemic region of the heart in 15 patients. Ischemia and myocardial viability were evaluated by assessment of symptoms and of results of radionuclide single photon emission computed tomography imaging, exercise tolerance testing, and 24-hour Holter monitoring. Results. No adverse events occurred as a result of the laser revascularization, although 1 patient with preoperative ventricular arrhythmias died 48 hours postoperatively as a result of refractory ventricular tachycardia. Angina class decreased significantly from base line values in patients who had undergone the procedure (mean Canadian Cardiovascular Association angina class, 3.5 ± 0.5 at base line, 1.6 ± 0.6 at 1 month, 1.5 ± 0.8 at 3 months, 1.9 ± 0.9 at 6 months, 1.8 ± 0.8 at 12 months; p < 0.002), and nitroglycerin requirements were similarly decreased in patients who had undergone laser revascularization (mean g/wk of sublingual nitroglycerin, 19 ± 4 at baseline, 5 ±3 at 1 month, 4 ± 2 at 3 months, 4 ± 2 at 6 months, 2 ± 1 at 12 months; p <0.02). Exercise tolerance testing demonstrated increase in exercise duration compared with base line values (mean minutes, 7.4 ± 3.1 at base line, 8.0 ± 3.9 at 1 month, 8.5 ± 4.4 at 3 months, and 9.0 ± 3.9 at 12 months; p >0.05); those increases were not large enough to be statistically significant, however. Conclusions. Our data are consistent with the concept that excimer transmyocardial laser revascularization in individuals with significant ischemic heart disease appears to be well tolerated, can be performed safely, and may lead to a reduction in ischemic symptomatology.

A Good Battle Cry is Half the Battle: Creating a Mission Statement with a Sense of Mission

All managers are compensated for their ability to make decisions. Operational managers focus on tactical decisions targeted at satisfying today's customers. Administrative managers will generally focus on strategic decisions targeted at tomorrow's customers. The effectiveness of each of these endeavors requires rational guidelines that detail where the manager's efforts should be directed. While policies are the primary guidelines followed by operational managers, administrative managers focus their efforts on mission statements. In addition to supplying managers with a general strategic direction and goals for the firm, the mission statement also establishes the foundation for how the firm's stakeholders are to be treated. Over the past several decades there has been a tremendous effort by researchers to synthesize the knowledge of strategic decision-making. What has been neglected in this task is the importance of creating and utilizing a mission statement. This article reviews the theoretical basis, purpose, and development of mission statements. Examples of excerpts from mission statements, along with one of the industry's finest mission statements, are provided.

A note on uniformization for dynamic non-negative systems

The classical technique of uniformization (or randomization) for bounded continuous-time Markov chains and Markov reward structures is extended to dynamic systems generated by arbitrary non-negative generators. Most notably, these include so-called input-output models in economic analysis. The results are of practical interest for both computational and theoretical purposes. Particularly, the recursive computation and the limiting behaviour of cumulative reward structures for non-negative dynamic systems is concluded as a special application. Two numerical examples are included to illustrate the conditions and the results.

A note on uniformization for dynamic non-negative systems

The classical technique of uniformization (or randomization) for bounded continuous-time Markov chains and Markov reward structures is extended to dynamic systems generated by arbitrary non-negative generators. Most notably, these include so-called input-output models in economic analysis. The results are of practical interest for both computational and theoretical purposes. Particularly, the recursive computation and the limiting behaviour of cumulative reward structures for non-negative dynamic systems is concluded as a special application. Two numerical examples are included to illustrate the conditions and the results.

Stories of Schools/Teacher Stories: A Two-Part Invention on the Walls Theme

Patterned in the style of a musical invention, this work adopts Clandinin and Connelly’s metaphor of a professional knowledge landscape (1995), Olson’s conceptualization of the narrative authority (1993, 1995) of teacher knowledge, and my idea that teachers develop their knowledge in knowledge communities (Craig 1992, 1995a, 1995b, 1998). The first invention outlines the stories of school (Clandinin & Connelly 1996) that Riverview School and Evergreen School were given and the changes that take place over time. The second invention features beginning teacher, Benita Dalton, and her narratives of experience lived and told in the two school contexts. Relating the teacher’s stories to the narrative accounts of the two campuses illustrates the extent to which context shapes teachers’ practices and bounds their knowing. The work sheds much light on the subtle complexities of teachers’ professional knowledge landscapes and adds to the conceptual base of a line of inquiry that focuses on the shaping effect of context on teachers’ knowledge developments.An invention, loosely defined, involves the creation, through thought and/or action, of something that did not exist before. Written in the style of a musical invention, this piece is composed of two parts featuring the stories of two schools played against the evolving stories of a teacher who worked in both contexts. While the two parts of the invention both develop the walls theme, each unfolds in a different manner. The two variations which constitute the first part of the invention center on the stories of school (Clandinin & Connelly 1996) that Riverview School and Evergreen School were given and examines how these stories changed over time. The two variations that comprise the second part of the invention highlight beginning teacher, Benita Dalton, her stories of experience (Connelly & Clandinin 1990) lived and told at the two schools, and shifts that took place in her knowledge development. Connecting the fine-grained accounts of an individual with the coarse-grained accounts of schools reveals the extent to which stories of school influence teachers’ practices, set the horizons of what is available for teachers to come to know, and adds to the conceptual base of a line of research that examines the how teachers’ knowledge developments are influenced by context.The work begins with introductions to Benita Dalton and me, the teacher and the researcher in the study. Discussions of the research method and the theoretical framework appear next. These preliminary sketches prepare the reader for the two-part invention that follows. They lay the methodological groundwork as well as provide lenses with which to view, and a language with which to describe, contextual experiences. The next segment of the piece is Part I of the Invention comprised of Variation I: A Narrative Account of Riverview School, Variation II: A Narrative Account of Evergreen School, and a reflective coda on stories of schools. These passages bring the first part of the invention to closure. Next comes Invention II, the second movement of the piece, featuring Variation I: A Story of Benita’s Experience at Riverview and Variation II: A Story of Benita’s Experience at Evergreen. As with the first part of the invention, a reflective coda appears at the end of Benita’s stories of experience that concludes the second part of the invention. The article ends with a grand finale, where the parallel stories developed in the invention’s two parts are intentionally brought together for practical and theoretical purposes. These closing passages specifically address the principle question, the simple melody around which this two-part inquiry/invention has been constructed/composed: How does context affect teachers’ knowledge developments?

Beta-glycosidase from the hyperthermophilic archaeon Sulfolobus solfataricus: structure and activity in the presence of alcohols.

beta-Glycosidase from the extreme thermophilic archaeon Sulfolobus solfataricus is a tetrameric protein with a molecular mass of 240 kDa, stable in the presence of detergents, and with a maximal activity at temperatures above 95 degrees C. Understanding the structure-activity relationships of the enzyme under different conditions is of fundamental importance for both theoretical and applicative purposes. In this paper we report the effect of methanol, ethanol, 1-propanol, and 1-butanol on the activity of S. solfataricus beta-glycosidase expressed in Escherichia coli. The alcohols stimulated the enzyme activity, with 1-butanol producing its maximum effect at a lower concentration than the other alcohols. The structure of the enzyme was studied in the presence of 1-butanol by circular dichroism, and Fourier-transform infrared and fluorescence spectroscopies. Circular dichroism and steady-state fluorescence measurements revealed that at low temperatures the presence of the alcohol produced no significant changes in the tertiary structure of the enzyme. However, time-resolved fluorescence data showed that the alcohol modifies the protein microenvironment, leading to a more flexible enzyme structure, which is probably responsible for the enhanced enzymatic activity.

Associative processes in addiction and reward. The role of amygdala-ventral striatal subsystems.

Only recently have the functional implications of the organization of the ventral striatum, amygdala, and related limbic-cortical structures, and their neuroanatomical interactions begun to be clarified. Processes of activation and reward have long been associated with the NAcc and its dopamine innervation, but the precise relationships between these constructs have remained elusive. We have sought to enrich our understanding of the special role of the ventral striatum in coordinating the contribution of different functional subsystems to confer flexibility, as well as coherence and vigor, to goal-directed behavior, through different forms of associative learning. Such appetitive behavior comprises many subcomponents, some of which we have isolated in these experiments to reveal that, not surprisingly, the mechanisms by which an animal sequences responding to reach a goal are complex. The data reveal how the different components, pavlovian approach (or sign-tracking), conditioned reinforcement (whereby pavlovian stimuli control goal-directed action), and also more general response-invigorating processes (often called "activation," "stress," or "drive") may be integrated within the ventral striatum through convergent interactions of the amygdala, other limbic cortical structures, and the mesolimbic dopamine system to produce coherent behavior. The position is probably not far different when considering aversively motivated behavior. Although it may be necessary to employ simplified, even abstract, paradigms for isolating these mechanisms, their concerted action can readily be appreciated in an adaptive, functional setting, such as the responding by rats for intravenous cocaine under a second-order schedule of reinforcement. Here, the interactions of primary reinforcement, psychomotor activation, pavlovian conditioning, and the control that drug cues exert over the integrated drug-seeking response can be seen to operate both serially and concurrently. The power of our analytic techniques for understanding complex motivated behavior has been evident for some time. However, the crucial point is that we are now able to map these components with increasing certainty onto discrete amygdaloid, and other limbic cortical-ventral striatal subsystems. The neural dissection of these mechanisms also serves an important theoretical purpose in helping to validate the various hypothetical constructs and further developing theory. Major challenges remain, not the least of which is an understanding of the operation of the ventral striatum together with its dopaminergic innervation and its interactions with the basolateral amygdala, hippocampal formation, and prefrontal cortex at a more mechanistic, neuronal level.

Duality for modules over finite rings and applications to coding theory

This paper sets a foundation for the study of linear codes over finite rings. The finite Frobenius rings are singled out as the most appropriate for coding theoretic purposes because two classical theorems of MacWilliams, the extension theorem and the MacWilliams identities, generalize from finite fields to finite Frobenius rings. It is over Frobenius rings that certain key identifications can be made between the ring and its complex characters.

Representing Cognitive Activity in Complex Tasks

Although cognitive theory has been recognized as essential for the analysis of human–computer interaction (HCI), the representations that have been developed have been directed more toward theoretic purposes than practical application. To bridge the gap between theory and application, representations need to satisfy requirements for broad scope, a unified theoretical basis, and abstraction. Interacting cognitive subsystems (ICS) is proposed as a unified cognitive theory that can be used as the basis for such representations, and two approaches based on the theory are described. One entails the description of cognitive task models, which are a relatively complete representation of the cognitive activity required of a user in the coarse of an interaction. The other entails the production of less complete diagrammatic notations, which are intended to provide support in small-scale problem identification and resolution and which can be applied across tasks, visual interface, and sound interface issues and can handle static and dynamic situations. Although the former can be implemented in a production-rule expert system (ICSpert) and , therefore, does not require detailed modeling knowledge an the part of the analyst, the latter is a pencil-and-paper technique that does require theoretical knowledge but is intended to facilitate the acquisition of such knowledge in the interest of educating its users about the human aspects HCI. The representations differ in the knowledge required for their use, in the support that they offer, and in the situations for which they are appropriate. They have been used to represent problems from experimental situations, core HCI scenarios, a d red-world design projects. They share breadth of scope and abstraction, and their parent theory supports transfer of knowledge across domains of application and from older to newer technologies and feedback between the domain of application and the domain of theory.