Theoretical Purposes Research Articles

Science teaching: science teachers in Trinidad and Tobago share their stories

ABSTRACTQualitative narrative inquiry using exploratory interviews with five experienced secondary school science teachers in Trinidad and Tobago were analysed to reveal what learnings can be derived from the experiences and stories shared by these individuals. The stories present science teaching as an evolutionary process, which portrays science teaching with the following attributes: a work in progress, a haven for students, a lifelong vocation, and a personal commitment. Integral elements of science teaching as a process rather than a product in an atmosphere of discipline, respect, and trustworthiness were revealed. While this work is instructive for aspiring teachers and has several implications for teacher preparation programmes, the aim in this instance is to share the stories of these five teachers, and in that regard it serves a celebratory rather than a theoretical purpose.

Subharmonic resonance and critical eccentricity for the classical hydrogen atomic system

Subharmonic resonance behaviors are investigated for the classical hydrogen atom, with classical radiation damping and circularly polarized light acting on the classical electron. This study is intended for both potential experimental applications as well as for deeper theoretical purposes. Long resonant states are predicted for realistic Rydberg atoms and highly excited hydrogen states. Several previously undiscovered physical effects are predicted. First, the semimajor axis remains relatively constant when in subharmonic resonance; second, the eccentricity steadily increases until a maximum, critical value is reached, at which point orbital decay sets in. If the initial orbit is circular, this critical eccentricity value is shown to always be the same for each subharmonic condition, regardless of the initial orbital radius. An analytic derivation for this result is presented. The illustrated dynamics are of interest for the classical theory of stochastic electrodynamics (SED) regarding whether SED can fundamentally describe more of quantum phenomena, particularly atomic excited state behavior and related emission and absorption spectra. Also of interest are how classical resonances can be imposed on a near continuum of quantum states. Finally, there may be future technological applications, such as “reading” and “writing” information into Rydberg atoms in the form of subharmonic resonances.

Exploring SDN & NFV in 5G Using ONOS & POX Controllers

This article describes how novel functionalities will take advantage of the cloud networking and will gradually replace the existing infrastructure of mobile networks with a virtualized one. Two technologies, namely software defined networking (SDN) and network function virtualization (NFV), offer their important benefits and a combination of them is an answer to the demands raised, such as central office re-architected as a data center (CORD). Open network operating system (ONOS) and POX are SDN controllers and offer an option to combine SDN and NFV addressing many ongoing problems in the field of mobile networks. In this paper, technologies and both controllers are compared and contrasted. Indicative cases of topologies are simulated and help evaluating both controllers. According to the experimental findings, ONOS is one of the most important controllers for practical, theoretical, research and educational purposes, while POX is a useful and simpler controller for other educative applications.

The Geography of Research on LGBTQ Life: Why sociologists should study the South, rural queers, and ordinary cities

AbstractOver the past 20 years, sociological research on LGBTQ people and communities has disproportionately studied coastal regions and big cities in the United States. Scholars pay the most attention to queer urban life in “great cities” like New York, San Francisco, Los Angeles, and Chicago and understudy lesbian, gay, bisexual, transgender, and queer (LGBTQ) life in the South, rural and suburban areas, and ordinary cities. This research ignores demographic evidence about where LGBTQ people live in the United States. I argue that these geographical choices—born out of convenience or theoretical purpose—shape the approach to studying queer life and the unintentional reproduction of a middle‐class, cosmopolitan universal gay subject. I chart a future path for sociology research on LGBTQ life that accounts for geography and moves beyond metronormativity.

Rejuvenating functional responses with renewal theory.

Functional responses are widely used to describe interactions and resource exchange between individuals in ecology. The form given to functional responses dramatically affects the dynamics and stability of populations and communities. Despite their importance, functional responses are generally considered with a phenomenological approach, without clear mechanistic justifications from individual traits and behaviours. Here, we develop a bottom-up stochastic framework grounded in renewal theory that shows how functional responses emerge from the level of the individuals through the decomposition of interactions into different activities. Our framework has many applications for conceptual, theoretical and empirical purposes. First, we show how the mean and variance of classical functional responses are obtained with explicit ecological assumptions, for instance regarding foraging behaviours. Second, we give examples in specific ecological contexts, such as in nuptial-feeding species or size-dependent handling times. Finally, we demonstrate how to analyse data with our framework, especially highlighting that observed variability in the number of interactions can be used to infer parameters and compare functional response models.

Phytoindicators of ecosystem dynamics in ring-bank ukrainian polissia

The publication discusses the study results of energy dynamics in ecosystems. The goal of the study is to search for objective parameters to determine the indicator of the ecosystem dynamics and basing on the above-ground phytomass quantitative indices, its age and changes of floristic composition we demonstrate the possibility of the accurate phytoindication assessment of ecosystems dynamics. It is determined that the indicators of above-ground phytomass naturally increase during self-development of natural ecosystems (autogenic succession).Materials and methods. The above-ground phytomass is measured in ecosystems that are at different stages of autogenic succession. In order to balance the fluctuation of the indicators, that was caused by the domination of species with different types of photosynthesis, the correction for the age of the above-ground phytomass was used.Results. The dynamics indicator increases during the autogenic succession. External influences deflect it from the main trend. The anthropogenic influence often displaces succession in the opposite direction. The method was tested on the territory of Right-Bank Ukrainian Polissia. Expansion of the database of results of dynamic indicator determination allows to calculate this indicator with accuracy sufficient for practical and theoretical purposes. Such methods allow studying ecosystem thermodynamics (entropy and energy stocks) and ecosystem dynamics in noninvasive and non-contact way without affecting of plant biodiversity. Such approaches could be the most suitable for conducting studies on natural protected areas. Within such objects, it is not allowed to remove the above-ground phytomass, to determine the energy and dynamic indicators.Conclusion. The unit that will correspond the self-development stage, is an index that is directly proportional to the aboveground phytomass quantity and its age. The ecosystem entropy value will be inversely proportional to the self-development stage index. This index can be determined by classical phytoindication methods upon detailed database availability. Measurement errors, associated with phytoindication method range from 3 % to 10 % comparing to 5-10 % for direct method, are commensurate. The phytoindication approach allows application of this methodology on the protected areas. The index of the ecosystems self-development stage can be used to predict the development of specific studied plots and for the needs of ecosystem classification

О теоретических основах аудита

Th e article considers the theoretical basis of audit as the second fl oor of the three — storey building of audit science (when the fi rst fl oor is occupied by fundamental and related Sciences, and the third — specifi c scientifi c and practical developments in the fi eld of audit). Th e necessity of development of these bases, their place in the system of audit Sciences and their desired content is analyzed. It is illustrated that they can have, in addition to a purely theoretical purpose, and direct access to the solution of practical problems of audit.

Filozofia wychowania jako filozofia

In the article the Author analyzes different ways of understanding and practicing the philosophy of education. This analysis leads to the conclusion that methodological status of philosophy of education is indefinite, and this is an important issue that should be considered. The Author proposes to distinguish the pedagogical philosophy of education from the philosophy of education as a philosophy in the strict sense. The purpose of pedagogical reflection is to improve the process of education. The goal of philosophy is to understand the nature and essence of education, therefore it is a purely theoretical purpose. The Author refers to the classical approach of philosophy being love of wisdom, according to which the philosophy is a disinterested contemplation of truth.

English

The non-conforming linear (P1) triangular FEM can be viewed as a kind of the discontinuous Galerkin method, and is attractive in both the theoretical and practical purposes. Since various error constants must be quantitatively evaluated for its accurate a priori and a posteriori error estimates, we derive their theoretical upper bounds and some computational results. In particular, the Babuska-Aziz maximum angle condition is required just as in the case of the conforming P1 triangle. Some applications and numerical results are also included to see the validity and effectiveness of our analysis.

The Key to Organizational Sustainability: Nurturing a Culture of Change

Unless they are constructed for purely theoretical purposes, all human organizations exist in their own particular environments. Those environments are subject to change. Unless the organization accommodates the changing environment. The chances of it continuing to serve the needs of its stakeholders will diminish. At a certain point as the needs of the stakeholders of the organization will cease to be served and the organization will no longer be sustainable. When the organization ceases to be sustainable it will cease to exits in its present form. The problem of organizational sustainability has been intensively studied. The issue of organizational resistance to change has been historically approached from the perspective of militating organizational resistance to a particular change initiative. In this paper, the social and historical roots of resistance to change are explored, and a new strategy to accommodate organizational change is developed. That new strategy is to adopt and nurture a culture of change. The first step in creating an organizational culture of change is to make change an everyday expectation by adjusting the organizational structure to encourage the assumption of power, authority and creativity throughout the organization. The basic four structures of organization are surveyed, and the type of structure that has been found to be most accepting and supporting of change is the type that has come to be known as an adhocracy. © 2018 John Wiley & Sons, Ltd.

A polyhedral study of the cardinality constrained multi-cycle and multi-chain problem on directed graphs

In this paper, we study the Cardinality Constrained Multi-cycle Problem (CCMcP) and the Cardinality Constrained Cycle and Chain Problem (CCCCP). A feasible solution allows one or more cardinality-constrained cycles to exist on the digraph. A vertex can only be involved in at most one cycle, and there may be vertices not involved in any cycles. The CCCCP has an additional set of vertices that can only serve–and are the only vertices that can serve–as the starting vertex of a chain. Apart from cycles, a feasible solution to the CCCCP may also contain multiple cardinality-constrained chains. A vertex can be involved in a chain or a cycle, but not both. Both of the CCMcP and the CCCCP are NP-hard.This paper focuses on the polyhedral study of the arc-based formulations for both problems. We prove that 3 classes of constraints are facet-defining for the CCMcP polytope, identify 4 new classes of constraints and prove their validity. We then prove that the non-negativity and the degree constraints are facet-defining for the CCCCP polytope. Even though we cannot expect to find a complete polyhedral description (CPD) of the CCMcP or the CCCCP, as both problems are NP-hard, any partial description is always interesting for both theoretical and computational purposes, since the wider the linear description, the less need for branching. A CPD is composed of facet-defining constraints, hence the major contribution of this paper is one step towards finding a CPD for the CCMcP and the CCCCP. We tested the strengths of the facet-defining constraints and new valid constraints on two sets of randomly generated data instances. We reported the numerical results and discussed future research directions.

Microbiomes of North American Triatominae: The Grounds for Chagas Disease Epidemiology.

Insect microbiomes influence many fundamental host traits, including functions of practical significance such as their capacity as vectors to transmit parasites and pathogens. The knowledge on the diversity and development of the gut microbiomes in various blood feeding insects is thus crucial not only for theoretical purposes, but also for the development of better disease control strategies. In Triatominae (Heteroptera: Reduviidae), the blood feeding vectors of Chagas disease in South America and parts of North America, the investigation of the microbiomes is in its infancy. The few studies done on microbiomes of South American Triatominae species indicate a relatively low taxonomic diversity and a high host specificity. We designed a comparative survey to serve several purposes: (I) to obtain a better insight into the overall microbiome diversity in different species, (II) to check the long term stability of the interspecific differences, (III) to describe the ontogenetic changes of the microbiome, and (IV) to determine the potential correlation between microbiome composition and presence of Trypanosoma cruzi, the causative agent of Chagas disease. Using 16S amplicons of two abundant species from the southern US, and four laboratory reared colonies, we showed that the microbiome composition is determined by host species, rather than locality or environment. The OTUs (Operational Taxonomic Units) determination confirms a low microbiome diversity, with 12-17 main OTUs detected in wild populations of T. sanguisuga and T. protracta. Among the dominant bacterial taxa are Acinetobacter and Proteiniphilum but also the symbiotic bacterium Arsenophonus triatominarum, previously believed to only live intracellularly. The possibility of ontogenetic microbiome changes was evaluated in all six developmental stages and feces of the laboratory reared model Rhodnius prolixus. We detected considerable changes along the host's ontogeny, including clear trends in the abundance variation of the three dominant bacteria, namely Enterococcus, Acinetobacter, and Arsenophonus. Finally, we screened the samples for the presence of Trypanosoma cruzi. Comparing the parasite presence with the microbiome composition, we assessed the possible significance of the latter in the epidemiology of the disease. Particularly, we found a trend toward more diverse microbiomes in Trypanosoma cruzi positive T. protracta specimens.

Testing principal- versus medial-axis accounts of global spatial reorientation.

Determination of a direction of travel is a necessary component of successful navigation, and various species appear to use the geometric shape (global geometric cues) of an environment to determine direction. Yet, debate remains concerning which objective shape parameter is responsible for spatial reorientation via global geometric cues. For example, the principal axis of space, which runs through the centroid and approximate length of the space, and the medial axis of space, a trunk and branch system that fills the shape, have each been suggested as a basis to explain global spatial reorientation. As the principal- and medial-axis accounts appear to have substantial theoretical implications regarding the nature of shape perception, spatial memory, and the underlying psychological representations of space, it appears critical to empirically differentiate between these global geometric accounts. The present experiment explicitly placed predictions from the principal- and medial-axis-based accounts of global spatial reorientation in conflict for theoretical diagnostic purposes. We used a standard reorientation paradigm in which human participants first reoriented in a rectangular environment; subsequent testing in a critical I-shaped enclosure allowed dissociation of the principal- or medial-axis-based accounts. We show that reorientation in the I-shaped enclosure was consistent with the principal-axis account and inconsistent with the medial-axis account. We suggest that the use of the principal axis for spatial reorientation is a relatively simple and efficient way to establish directionality that would be advantageous over a more complex and less efficient medial-axis-based account. (PsycINFO Database Record

Three Pathways to Case Selection in International Business: A Twenty–Year Review, Analysis and Synthesis

With its focus on locational context, International Business (IB) is a prime candidate for the application of Case Study (CS) methodology. Yet many IB scholars still have doubts about CSs, possibly because strategies for their selection and disclosure procedures may lack rigor. The purpose of this article is to document and discuss CS selection in IB research, make suggestions for improvement, and thus raise the standard and status of CS research.Using qualitative content analysis, this paper examines CS selection strategies in four IB journals (1995–2014), relating them to chosen theoretical purposes and logics employed. Our results indicate that 12% of the 333 investigated CS articles lacked a section on methodology, and 41% of papers reported no indication of how CSs were selected. Drawing insights from the dataset, we propose and distinguish between theory-driven and phenomenon-driven CS selection approaches. In light of our evidence, best-practice papers are identified and apportioned to coherent pathways connecting theoretical purpose, logic and CS selection strategies. In doing so, we address the link between case selection and theorizing in CSs and advocate greater methodological sophistication and transparency of CS selection reporting in IB research.

Large deformation bending responses of nanotube-reinforced polymer composite panel structure: Numerical and experimental analyses

The large deformation deflection responses of randomly oriented multi-walled carbon nanotube-reinforced polymer composite structures were examined theoretically using a novel higher order shear deformation kinematic model. Moreover, the excess geometrical distortion within the structure is incorporated via the full geometrically nonlinear strain–deformation relations (Green–Lagrange strain) including all of the nonlinear higher order terms to achieve the generality. The randomly oriented nanotube-reinforced polymer composite properties were evaluated computationally via Mori–Tanaka scheme for the theoretical analysis purpose. The deflection responses were evaluated numerically using an original MATLAB program with the help of the direct iterative method and finite element steps. The performance of the currently developed numerical model was verified by solving various numerical examples for the convergence and subsequent comparison purpose. Also, the deflection values were evaluated experimentally and compared with the current numerical results using the experimentally obtained elastic properties. Finally, the generality and the applicability of the currently developed higher order nonlinear finite element model is revealed by solving various numerical examples.

Correlation of base oil viscosity in grease with vibration severity of damaged rolling bearings

PurposeThe main objective of the paper is to explore the theoretical correlation of base oil viscosity in grease and to study the effect of grease grade on mechanical vibrations associated with the damaged rolling bearings.Design/methodology/approachFor theoretical purposes, formulation theory of dimensional analysis was implemented. Experiments were then performed on the test bearings lubricated with three different types of greases, namely, SKF LGHP2, SKF LGMT3 and SKF LGWA2.FindingsThe numerical results obtained from the theoretical model along with the results of experiments show that the vibration amplitudes of the defective bearings come down to a lower level when it is lubricated with the grease of a higher base oil viscosity.Research limitations/implicationsThe promising results from the theoretical model make it usable for the practical rotating machineries applying a variety of the rolling bearings. Consequently, if the bearing is not severely damaged, its performance can be increased by lubricating it with thicker grease.Originality/valueDespite many significant contributions in the field to detect the presence of defects, not many studies have been performed that relate the lubrication condition of the rolling bearings with the vibration response, because around 50-75% of the bearing failures are attributed to be lubrication related. Hence, there is need to develop a mathematical model that can correlate the vibration severity of the bearings with viscosity of the lubricant oil in the greases along with other design and operating parameters.

Factors predisposing to conversion from laparoscopic to open cholecystectomy

The conversion of a laparoscopic cholecystectomy (LC) to an open procedure seems to be multifactorial, be affected by factors related to the patient, the gallbladder’s pathology and the surgeon. Among the more than twenty parameters which have been studied as possible predisposing factors for conversion, current literature addresses that: a male patient, above 65 years old, with American Society of Anaesthesiology (ASA) score ≥3, suffering from acute cholecystitis, with a thickened gallbladder’s wall on preoperative CT and an impacted stone in infundibulum or Mirizzi syndrome as intraoperative finding, who was operated on more than 72 hours from the onset of symptoms, by a non-laparoscopic surgeon, represents the most likely candidate for conversion from LC to open surgery. The probability increases further in the presence of malnutrition and/or cirrhosis. The proposed predictive scores for conversion have not yet found worldwide acceptance and their use is limited to theoretical or training purposes. Even patients with maximum predictive score, do not have a 100% probability for conversion. An experienced surgeon can complete a difficult LC successfully in high-risk surgical patient using the subtotal LC. The need for conversion to laparotomy should be considered as neither a failure nor a complication, but as an attempt to be avoided intra- or post-operative complications. The present review attempts to present the most recent knowledge on the field “conversion from LC to open surgery”.

The Problem of Lived Experience in The Cracked Mirror

The paper argues that the problem of ‘lived experience’ in The Cracked Mirror cannot be grasped phenomenologically but through the Derridian notion of supplement. The notion of supplement problematizes the coherence of phenomenological ego and makes it fractured and delayed. The Cracked Mirror therefore poses the ethical problem in representing the otherness of dalit experience for theoretical purpose. Present paper would try to resolve the problem of representation in The Cracked Mirror through Kant’s notion of ‘Reflective Judgment’ in Critique of Judgment. Reflective judgment overcomes the logic of recognition as against the determinative judgment and opens up the possibility of the construction of the new concepts which can articulate the dalit experiences in social sciences. In this way, the present paper will try to resolve the dialectics between the singularity of the experience and the universality of judgment.

How to measure sessions of mobile phone use? Quantification, evaluation, and applications

Research on mobile phone use often starts with the question of how much time users spend using their phones. The question involves an equal-length measure that captures the duration of mobile phone use but does not tackle the other temporal characteristics of user behavior, such as frequency, timing, and sequence. In this study, we propose a variable-length measure called “session” to uncover the unmeasured temporal characteristics. We use an open source dataset to demonstrate how to quantify sessions, aggregate the sessions to higher units of analysis within and across users, evaluate the results, and apply the measure for theoretical or practical purposes.

Exchangeable trait allocations

Trait allocations are a class of combinatorial structures in which data may belong to multiple groups and may have different levels of belonging in each group. Often the data are also exchangeable, i.e., their joint distribution is invariant to reordering. In clustering—a special case of trait allocation—exchangeability implies the existence of both a de Finetti representation and an exchangeable partition probability function (EPPF), distributional representations useful for computational and theoretical purposes. In this work, we develop the analogous de Finetti representation and exchangeable trait probability function (ETPF) for trait allocations, along with a characterization of all trait allocations with an ETPF. Unlike previous feature allocation characterizations, our proofs fully capture single-occurrence “dust” groups. We further introduce a novel constrained version of the ETPF that we use to establish an intuitive connection between the probability functions for clustering, feature allocations, and trait allocations. As an application of our general theory, we characterize the distribution of all edge-exchangeable graphs, a class of recently-developed models that captures realistic sparse graph sequences.