Realistic Considerations Research Articles

A Critical Realist Guide to Developing Theory with Systematic Literature Reviews

This working paper has been thoroughly revised and superseded by two distinct articles, both available at SSRN. The first focuses on developing theory with literature reviews: Okoli, Chitu. The View from Giants’ Shoulders: Developing Theory with Theory-Mining Systematic Literature Reviews. SSRN Working Paper Series, December 8, 2015. This article identifies theory-mining reviews, which are literature reviews that extract and synthesize theoretical concepts from the source primary studies. The article demonstrates by citation analysis that, in information systems research, this kind of literature review is more highly cited than other kinds of literature review. The article provides detailed guidelines to writing a high-quality theory-mining review. The second subsequent article offers various comments on literature reviews from a critical realist perspective: Okoli, Chitu. Critical Realist Considerations for Literature Reviews. SSRN Working Paper Series, December 8, 2015. Using the systematic review framework, it offers various comments from a critical realist lense on uncovering real mechanisms underlying theoretical phenomena. It also offers other general comments on the literature reviewing practice beyond theory-building.

The influence of changing stratification conditions on barotropic tidal transport and its implications for seasonal and secular changes of tides

Ocean tides are changing on secular and seasonal time scales with much larger magnitudes than we would expect from changes in the gravitational forcing. In order to understand the impact of seasonal and long term changes of stratification on ocean tides, the influence of eddy viscosity and bottom drag on the barotropic transport of an oscillating flow is analyzed by analytical and numerical models. The shallow water equations without the advective terms are solved and analytical solutions are obtained in cases of vertically and temporally constant eddy viscosity, and linearized bottom drag. The numerical model (General Ocean Turbulence Model, GOTM) allows for a more realistic consideration of eddy viscosity, non-linear bottom friction and vertical density profiles. Results of analytical and numerical models are consistent and show that changing stratification conditions, which in turn change the eddy viscosity profile and bottom drag, modify the barotropic transport by 1–5%. Specifically, the analytical model points out that eddy viscosity Av is negative (positive) correlated with the barotropic transport if Avω/αb2<1(Avω/αb2>1), where αb describes the bottom friction coefficient and ω the frequency of the oscillating flow. Generally, these results suggest that in shallow seas the seasonal variations in stratification are a major factor for the observed seasonal modulation in tides. Further, a deepening of the mixed-layer depth by only 10m can change tidal transport by 1–2%, which might be relevant to understand secular trends of tides in a warming ocean.

An analytical model for reinforced concrete columns with lap splices

This paper presents a new analytical model formulation for simulating the lateral load–deformation response of reinforced concrete columns with deficient lap splices. The modeling approach proposed involves implementing bond stress vs. slip springs in the formulation of a fiber-based flexural macro-model. The analytical model directly reflects the influence of local bond slip deformations on the lateral load–displacement response of a reinforced concrete column under cyclic lateral loading, via consideration of local coupling between flexural deformations and slip deformations associated with either splitting or pullout bond failures, along the lap splice region. The flexible formulation of the model allows investigating the influence of using smooth reinforcing bars, presence of hooks, and strain penetration effects on the lateral load behavior of a column. The modeling approach presented is believed to be a significant improvement, towards realistic consideration of the influence of bond slip deformations and anchorage failures on the seismic response of reinforced concrete buildings.

When to Autopsy: Idealistic and Realistic Considerations

The decision to perform an autopsy depends on many things, but at the least, it rests with local statutory responsibility and the competent forensic pathologist's perceived needs of the specific case. Although cause and manner of death are at the heart of the mission of the forensic pathologist, there are other obligations that should be considered, such as: questions that could arise later, as well as the impact of an incorrect opinion on the affected family and society. Standards have been developed by the National Association of Medical Examiners (NAME) which state when an autopsy should be performed. The autopsy has value in nearly all cases; however, the indiscriminate use of the autopsy does not supersede the detailed gathering of pertinent investigative history. It cannot be performed in a vacuum. Idealistic virtues of the autopsy, even if based on experiential merit, must still meet the hard realism of budgets and staffing when it comes to categorical case selections for autopsy. Resources must be allocated rationally. The purpose of this discussion/review is to review considerations about whether or not to perform an autopsy, from an idealistic, and from a realistic viewpoint. The intent is not to promulgate dogma or zealous overindulgence in testing which could overburden death investigative systems that already have critical limitations in budget and staffing. The conscientious role of the physician pathologist is emphasized.

Stem Cell-Based Therapies: Promises, Obstacles, Discordance, and the Agora

Stem cell research has entered the public consciousness through the media. Proponents and opponents of all such research, or of human embryonic stem cell research specifically, engage in heated exchanges in the modern public forum where stakeholders negotiate, the agora. One common claim that emerges from the fray is that a particular type of stem cell research should be pursued as the most promising path toward the reduction of suffering and untimely death for all of humanity. Upon evaluation, experimental data regarding the potential role of stem cells in regenerative therapies for three conditions-spinal cord injury, type 1 diabetes, and cardiovascular disease-tell distinct, complex, and inconclusive stories. Further analyses in this article incorporate realistic considerations of a broad range of relevant factors: limited funding for biomedical research, media motives, the discordance hypothesis of evolutionary medicine, the relationship between religion and science, medical care in developing nations, and culture wars over abortion. Holistic investigation inspired by the current agora conversation supports the need to drastically change interactions regarding stem cell research so that its potential to benefit humanity may be more fully realized.

Earthquakes, Existing Buildings and Seismic Design Codes in Turkey

From worldwide observations made after the occurrence of earthquakes, as well as the tremendous amount of experimental, analytical and numerical studies, significant contributions have been made for a better understanding of the characteristics of earthquakes, and effects of earthquakes on existing structural systems. Consequently, seismic design codes are revised in a parallel fashion by integrating new concepts towards more realistic considerations of seismic demand, seismic response and seismic capacity. In this paper, after outlining the performance of existing buildings in Turkey during recent earthquakes (particularly Kocaeli 1999 and Duzce 1999 Earthquakes), and by focusing on the observed common structural deficiencies, a brief summary of the evolution of the Turkish Seismic Design Code in the last decades is presented. It is important to note that the poor seismic performance of existing buildings in Turkey outlined in this study is not directly related to the inefficiency of the relevant seismic design codes, but rather to extremely low quality construction and the absence of a strict inspection system at the time of their construction. It should also be highlighted that the lessons learnt from the catastrophic consequences of recent earthquakes, revisions in the seismic design code and the developments in the material and workmanship characteristics have significantly improved the quality of newer constructions in Turkey in the last decade.

Next approximation of the random walk theory for Brownian coagulation

The new approach to Brownian coagulation theory, developed in the authors’ previous papers and based on the simple random walk theory (with a fixed elementary walk distance of migrating particles), is further improved by more realistic consideration of random walks with stochastically distributed lengths. The interpolation expressions derived in the simple random walk approach avoiding semi-empirical assumptions of the traditional models, are justified (within the calculation accuracy) by new calculation results obtained in the next approximation of the random walk theory. The developed approach being applied to the problem of heavy vapour molecules condensation in a large trap, results in the improved description of the condensation rate in the transition regime.

The realistic consideration of human factors in model based simulation tools for the air traffic control domain

Advanced Air Traffic Management (ATM) concepts related to automation, airspace organization and operational procedures are driven by the overall goal to increase ATM system performance. Independently on the nature and/or impact of envisaged changes (e.g. from a short term procedure adjustment to a very long term operational concept or aid tools completion), the preliminary assessment of possible gains in airspace/airport capacity, safety and cost-effectiveness is done by running Model Based Simulations (MBSs, also known as Fast Time Simulations - FTS). Being a not human-in-the-loop technique, the reliability of a MBS results depend on the accuracy and significance of modeled human factors. Despite that, it can be observed in the practice that modeling tools commonly assume a generalized standardization of human behaviors and tasks and consider a very few range of work environment factors that, in the reality, affect the actual human-system performance. The present paper is aimed at opening a discussion about the possibility to keep task description and related weight at a high/general level, suitable for an efficient use of MBSs and, at the same time, increasing simulations reliability adopting some adjustment coming from the elaboration of further variables related to the human aspects of controllers workload.

Digital Reflectarray Considerations for Terrestrial Millimeter-Wave Imaging

We investigate how realistic architecture considerations affect the performance of wafer-scale electronically scanned millimeter-wave reflectarrays. Considering the application of a confocal Gregorian optics geometry with a small angular field of view, we examine how a reflectarray's discrete (digital) phase state quantization and electrical size impact scan angle accuracy and quantization lobe performance degradation. We quantify the impact of these effects on the camera's imaging performance and show that, for these reflectarrays, phase quantization of 2 bits is sufficient.

Data envelopment analysis based on maximin relative efficiency criterion

While gauging the performances of operating entities using imprecise information on the input and output importance weights, an entity is considered Farrell efficient as long as it outperforms its peers for at least one feasible combination of the weights for inputs and outputs. This paper argues that Farrell efficiency computations are based on an optimistic perspective and a Farrell-efficient entity may perform rather poorly when weights corresponding to realistic considerations are assigned to inputs and outputs. An entity is defined as robust efficient if its relative efficiency score reaches 1 in all feasible combinations of the input and output weights. A linear programming based approach is proposed to perform what is referred to as robust efficiency analysis to identify robust efficient entities. In contrast to Farrell efficiency analysis, robust efficiency analysis involves the computation of the lowest efficiency score that can be assigned to an entity relative to the highest score among all the entities where an identical combination of weights for inputs and outputs is applied. The production possibility set underlying the proposed approach is also defined and interpreted. An experimental study illustrates that when compared with Farrell efficiency analysis robust efficiency analysis has sharper discrimination capability and the entity it identifies as efficient has superior average performance.

African and Black Caribbean origin cancer survivors: a qualitative study of the narratives of causes, coping and care experiences

Objectives. Although there is evidence in the USA and UK to suggest that ethnic minority groups have an inferior experience of cancer care, few studies investigate ethnic disparities in satisfaction and care experiences among survivors. Patients’ illness perceptions (lay explanations for illness) and coping styles (emotional and behavioural) are influenced by ethnicity-related cultural beliefs and expectations. Depressive illness or fears of recurrence of cancer may also lead to poorer recovery and function. This paper investigates whether ethnic influences explain different coping behaviours, care experiences and help-seeking behaviours. Design. Eight participants of African or Black Caribbean origin were recruited from a London support group for a series of qualitative in-depth interviews. The interviews were recorded and transcribed, and the transcripts analysed using a framework method of qualitative data analysis. The emergent themes were tested and documented to reflect the issues of importance to patients. Results. Lay explanations of causes of cancer were complex and diverse reflecting cultural influences and the impact of contact with health professionals. Generally, positive views about cancer care were found, especially at the secondary care level. Primary care attracted mixed views. In contrast to American studies, no acknowledgement of discrimination on the basis of ethnicity was reported. The need to be resilient and think positively were widely acknowledged as coping strategies. Some coped by avoiding contemplation of their condition or diagnosis. Religious beliefs and practices provided coping mechanisms for some, and a means to improve confidence and avoid distressing contemplation about their condition. Family, friends and charitable groups also provided emotional and practical support. Conclusions. Subjects were generally satisfied with their care; different coping styles included positive attitudes, minimisation of difficulties or more realistic consideration of the impact of cancer.

Microfluidic devices: useful tools for bioprocess intensification.

The dawn of the new millennium saw a trend towards the dedicated use of microfluidic devices for process intensification in biotechnology. As the last decade went by, it became evident that this pattern was not a short-lived fad, since the deliverables related to this field of research have been consistently piling-up. The application of process intensification in biotechnology is therefore seemingly catching up with the trend already observed in the chemical engineering area, where the use of microfluidic devices has already been upgraded to production scale. The goal of the present work is therefore to provide an updated overview of the developments centered on the use of microfluidic devices for process intensification in biotechnology. Within such scope, particular focus will be given to different designs, configurations and modes of operation of microreactors, but reference to similar features regarding microfluidic devices in downstream processing will not be overlooked. Engineering considerations and fluid dynamics issues, namely related to the characterization of flow in microchannels, promotion of micromixing and predictive tools, will also be addressed, as well as reflection on the analytics required to take full advantage of the possibilities provided by microfluidic devices in process intensification. Strategies developed to ease the implementation of experimental set-ups anchored in the use of microfluidic devices will be briefly tackled. Finally, realistic considerations on the current advantages and limitation on the use of microfluidic devices for process intensification, as well as prospective near future developments in the field, will be presented.

Chinese upper elementary school mathematics teachers’ attitudes towards the place and value of problematic word problems in mathematics education

Word problems play a crucial role in mathematics education. However, the authenticity of word problems is quite controversial. In terms of the necessity of realistic considerations to be taken into account in the solution process, word problems have been classified into two categories: standard word problems (S-items) and problematic word problems (P-items). S-items refer to those problems involving the straightforward application of one or more arithmetical operations with the given numbers, whereas P-items call for the use of real-world knowledge and real-life experience in the problem-solving process. This study aims to explore how Chinese upper elementary school mathematics teachers think of the place and value of P-items in the elementary mathematics curriculum.

Toward Optimal Destriping of MODIS Data Using a Unidirectional Variational Model

Images acquired by the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard Terra and Aqua exhibit strong detector striping. This artifact is common to most pushbroom scanners and affects both visual interpretation and radiometric integrity of remotely sensed data. A considerable effort has been made to remove stripe noise and reduce its impact on high-level products. Despite the variety of destriping algorithms proposed in the literature, complete removal of stripes without signal distortion is yet to be overcome. In this paper, we tackle the striping issue from a variational angle. Basic statistical assumptions used in previous techniques are replaced by a much realistic geometrical consideration on the striping unidirectional variations. The resulting algorithm is tested on Aqua and Terra MODIS data contaminated with severe stripes and is shown to provide optimal qualitative and quantitative results.

Analogue Behavioral Modeling of GTO

An analog behavioral model of high power gate turn-off thyristor (GTO) is developed in this paper. The fundamental methodology for the modeling of this power electronic circuit is based on the use of the realistic diode consideration of non-linear junctions. This modeling technique enables to perform different simulations taking into account the turn-on and turn-off transient behaviors in real-time. The equivalent circuits were simulated with analog software developed in our laboratory. It was shown that the tested simple and compact model allows the generation of accurate physical characteristics of power thyristors under dynamic conditions. The model understudy was validated with analog simulations based on operational amplifier devices.

Enabling Technologies for a Practical Wireless Communication System Operating in TV White Space

This paper proposes the design of enabling technologies for practical wireless communication systems operating in the TV white space (TVWS). The main objective of this paper is to cover a macro perspective on the system design blocks including: (a) targeted use case applications and governing regulations, (b) channelization, physical (PHY) layer and medium access control (MAC) layer designs, and (c) achievable throughput and range. It is the intention of this paper to serve as a general guideline for designing wireless communication systems operating in TVWS. The core system design addresses both PHY and MAC layer issues with realistic system considerations. In the PHY layer, a channelization design that fits into the area-specific TV channels and a transceiver that enables data exchange in the TV bands are designed. In the MAC layer, a cognitive engine that manages access to vacant TV channels and MAC functionalities that facilitate effective medium access are also proposed. As a result, the system is capable of supporting up to a typical throughput of 80 Mbps, and a maximum number of 40 users, assuming all users performing the most bandwidth-hungry application in the use case scenario. The corresponding operating range is found reach up to 400 m.

Joint modified block replacement and production/inventory control policy for a failure-prone manufacturing cell

This paper considers a joint preventive maintenance (PM) and production/inventory control policy of an unreliable single machine, mono-product manufacturing cell with stochastic non-negligible corrective and preventive delays. The production/inventory control policy, which is based on the hedging point policy (HPP), consists in building and maintaining a safety stock of finished products in order to respond to demand and to avoid shortages during maintenance actions. Without considering the impact of preventive and corrective actions on the overall performance of the production system, most authors working in the reliability and maintainability domains confirm that the age-based preventive maintenance policy (ARP) outperforms the classical block-replacement policy (BRP). In order to reduce wastage incurred by the classical BRP, we consider a modified block replacement policy (MBRP), which consists in canceling a preventive maintenance action if the time elapsed since the last maintenance action exceeds a specified time threshold. The main objective of this paper is to determine the joint optimal policy that minimizes the overall cost, which is composed of corrective and preventive maintenance costs as well as inventory holding and backlog costs. A simulation model mimicking the dynamic and stochastic behavior of the manufacturing cell, based on more realistic considerations of the real behavior of industrial manufacturing cells, is proposed. Based on simulation results, the joint optimal MBRP/HPP parameters are obtained through a numerical approach that combines design of experiment, analysis of variance and response surface methodologies. The joint optimal MBRP/HPP policy is compared to classical joint ARP/HPP and BRP/HPP optimal policies, and the results show that the proposed MBRP/HPP outperforms the latter. Sensitivity analyses are also carried out in order to confirm the superiority of the proposed MBRP/HPP, and it is observed that for practitioners, the proposed joint MBRP/HPP offers not only cost savings, but is also easy to manage, as compared to the ARP/HPP policy.

Fifth-grade students’ approaches to and beliefs of mathematics word problem solving: a large sample Hungarian study

Mathematical word problems used in Verschaffel et al.’s (Learning and Instruction 7:339–359, 1994) study were applied in several follow-up studies. The goal of the present study was to replicate and extend the results of this line of research in a large sample of Hungarian students using an alternative set of data-gathering and data-analysis techniques. 4,037 students forming a nationwide representative sample of the Hungarian fifth-grade student population (aged 10–11) completed the test. The test contained five word problems from the list of 10 P(‘problematic)-items from Verschaffel et al.’s test. In contrast to all previous research in this domain, we used a multiple-choice format, where three options were given for each task: (a) routine-based, non-realistic answer, (b) numerical response that does take into account realistic considerations, (c) a realistic solution stating that the task cannot be solved. The hypotheses of this study were: (1) Students’ responses will confirm previous results, i.e. upper elementary school students prefer to respond to P-items by means of the routine-based answer; (2) Most students will demonstrate a more or less consistent preference for a given answer type (a, b or c) over problems; (3) Students’ school math marks will have low correlation indices with students’ achievement on these word problems. Our results confirm student’s overall tendency to follow non-realistic approaches when doing school word problem solving. The tendency even holds when confronting students with various kinds of realistic answers. Our results show that students demonstrate response patterns over problems, and that the correlation with math school performance is significant but small.

Beyond realistic considerations: modeling conceptions and controls in task examples with simple word problems

Using simple word problems, we analyze possible teacher conceptions on the process of problem solving, its goals and the choices that a problem solver can make in problem mathematization. We identify several possible teacher conceptions that would be responsible for the different didactical contracts that teachers create in the mathematics class. Using especially chosen and designed task examples, we demonstrate the diagnosis of teacher own controls in solving problems and in evaluating problem solutions. We also discuss characteristics of task examples that might promote a shift from a problem solving perspective to a modeling perspective that goes beyond merely accepting alternative solutions due to realistic considerations. This shift in perspective would be exhibited through a new understanding of the process of fitting mathematical models in problem situations.

Amending the Constitution of the Federal Republic of Nigeria 1999

AbstractThe amendment of the Constitution of the Federal Republic of Nigeria 1999 has not been free of controversies. The latest controversy dogging the amendment relates to whether or not it is necessary for the President to assent to the Bill of the National Assembly amending the Constitution, even after the amendment has been ratified by at least two-thirds of the Houses of Assembly of the States of the Federation. There are two schools of thought on this issue; each with sound arguments in support of their respective position. A dispassionate and realistic consideration of the issue has been undertaken in this article. The conclusion is reached that the provision of the constitution dealing with its amendment is not free from ambiguity. Its lack of clarity on its amendment procedure has made it obviously in dire need of amendment. Consequently, necessary suggestions on how to resolve the issues, including the amendment of the amendment-provision of the constitution have been proffered.