344 research outputs found

    Simulation-Based Research in Information Systems - Epistemic Implications and a Review of the Status Quo

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    Simulations provide a useful methodological approach for studying the behavior of complex socio- technical information systems (IS), in which humans and IT artifacts interact to process information. However, the use of simulations is relatively new in IS research and the current presence and impact of simulation-based studies is still limited. Furthermore, simulation-based research is quite different from other approaches, making it difficult to position and evaluate it adequately. Therefore, this paper first analyses the epistemic particularities of simulation- based IS research. Based on this analysis, a structured lit- erature review of the status quo of simulation-based IS research was conducted, to understand how IS scholars currently employ simulation. A comparison of the epis- temic particularities of simulation-based research with its status quo in IS literature allows to critically examine epistemic inferences in the respective research process. The results provide guidance for prospective simulation-based IS research through discussing the theory-based derivation of simulation models, as well as different simulation techniques, validation techniques, and simulation uses

    What, if anything, are topological maps for?

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    What, if anything, is the functional significance of spatial patterning in cortical feature maps? We ask this question of four major theories of cortical map formation: self-organizing maps, wiring optimization, place coding, and reaction-diffusion. We argue that (i) self-organizing maps yield spatial patterning only as a by-product of efficient mechanisms for developing environmentally appropriate distributions of feature preferences, (ii) wiring optimization assumes rather than explains a map-like organization, (iii) place-coding mechanisms can at best explain only a subset of maps in functional terms, and (iv) reaction-diffusion models suggest two factors in the evolution of maps, the first based on efficient development of feature distributions, and the second based on generating feature-specific long-range recurrent cortical circuitry. None of these explanations for the existence of topological maps requires spatial patterning in maps to be useful. Thus despite these useful frameworks for understanding how maps form and how they are wired, the possibility that patterns are merely epiphenomena in the evolution of mammalian neocortex cannot be rejected. The article is intended as a nontechnical introduction to the assumptions and predictions of these four important classes of models, along with other possible functional explanations for maps

    A computational analysis of the long-term regulation of arterial pressure

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    The asserted dominant role of the kidneys in the chronic regulation of blood pressure and in the etiology of hypertension has been debated since the 1970s. At the center of the theory is the observation that the acute relationships between arterial pressure and urine production—the acute pressure-diuresis and pressure-natriuresis curves—physiologically adapt to perturbations in pressure and/or changes in the rate of salt and volume intake. These adaptations, modulated by various interacting neurohumoral mechanisms, result in chronic relationships between water and salt excretion and pressure that are much steeper than the acute relationships. While the view that renal function is the dominant controller of arterial pressure has been supported by computer models of the cardiovascular system known as the “Guyton-Coleman model”, no unambiguous description of a computer model capturing chronic adaptation of acute renal function in blood pressure control has been presented. Here, such a model is developed with the goals of: 1. representing the relevant mechanisms in an identifiable mathematical model; 2. identifying model parameters using appropriate data; 3. validating model predictions in comparison to data; and 4. probing hypotheses regarding the long-term control of arterial pressure and the etiology of primary hypertension. The developed model reveals: long-term control of arterial blood pressure is primarily through the baroreflex arc and the renin-angiotensin system; and arterial stiffening provides a sufficient explanation for the etiology of primary hypertension associated with ageing. Furthermore, the model provides the first consistent explanation of the physiological response to chronic stimulation of the baroreflex

    The SIMPLEXYS experiment : real time expert systems in patient monitoring

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    Inverted theory networks

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    Includes bibliographical references (leaves 147-152).The logicatom is defined, and it is argued that this represents the quantum of knowledge. Theory networks encapsulating a set of logicatoms and the dynamic relations between them, are defined. It is shown that these structures call emulate cellular automaton systems and in particular, simulate universal Turing machines. The regulating priuciple of natural selection is formalised together with its necessary and sufficient conditions. It is proven that there exists inverted theory networks (an analogous construct to theory networks) that satisfy all the requirements specified for natural selection to regulate their dynamics. The applicability of inverted theory networks to modelling thought is analysed. Further, inverted theory networks are proposed as a candidate for the pregeometry hypothesised by Wheeler

    Digitalization beyond technology: Proposing an explanatory and predictive model for digital culture in organizations

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    Continuous technological advancements and digitalization are transforming organizations’ resources and capabilities, yet many have not adapted their corporate culture accordingly. Aligning with a digital-oriented culture archetype is crucial for successful digital transformation. This paper presents a research model that predicts digital culture in organizations based on traditional culture archetypes. Using cutting-edge multivariate analysis techniques, such as PLS-SEM, IPMA, or PLS-Predict, on a sample of 285 managers from Spanish companies, the results indicate that a People-oriented culture archetype is the most important for digital culture, while values inherent to Norms or Goals culture archetypes hinder it. The paper contributes to the development of Functionalist and Structuralist Theories of culture, demonstrating the interplay of micro-cultures and cultural archetypes within an organization.Junta de Andalucía SEJ-57

    Automated Validation of State-Based Client-Centric Isolation with TLA <sup>+</sup>

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    Clear consistency guarantees on data are paramount for the design and implementation of distributed systems. When implementing distributed applications, developers require approaches to verify the data consistency guarantees of an implementation choice. Crooks et al. define a state-based and client-centric model of database isolation. This paper formalizes this state-based model in, reproduces their examples and shows how to model check runtime traces and algorithms with this formalization. The formalized model in enables semi-automatic model checking for different implementation alternatives for transactional operations and allows checking of conformance to isolation levels. We reproduce examples of the original paper and confirm the isolation guarantees of the combination of the well-known 2-phase locking and 2-phase commit algorithms. Using model checking this formalization can also help finding bugs in incorrect specifications. This improves feasibility of automated checking of isolation guarantees in synthesized synchronization implementations and it provides an environment for experimenting with new designs.</p

    The Trust Decoder™: An Examination of an Individual\u27s Developmental Readiness to Trust in the Workplace

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    This research explores an individual\u27s self-perception of their own ability, motivation, and propensity to trust others for the purpose of validating a new construct: developmental readiness to trust others in the workplace. This construct expands research on developmental readiness to change and to lead by building a scale to measure an individual\u27s motivation and ability to trust others in the workplace. A previously validated scale developed by Frazier, Johnson, and Fainshmidt 2013 measuring propensity to trust was included the scale building process. All items measuring motivation to trust were newly developed for this study, items measuring trust ability were adapted and based on previous trust research by Mayer and Davis 1999. This was a mixed-methods study (qual) QUAN with 6 individual interviews and 417 surveys collected via an online survey using an item response scale of 1 to 7. Respondents were solicited through professional networks and Mechanical Turk. Construct validation resulted in a two-factor model measuring ability and motivation to trust, with propensity to trust as a subcategory under the motivation factor. Exploratory and confirmatory factor analyses were conducted and evidence supported the construct\u27s convergent and discriminant validity and reliability. This research contributes to the existing research on trust by examining an individual\u27s capability to trust others and their motivation. Motivation included both propensity and outcome orientation to trust others prior to entering a relationship. This dissertation is available in open access at AURA: Antioch University Repository and Archive, http://aura.antioch.edu/ and OhioLINK ETD Center, https://etd.ohiolink.edu and is accompanied by an Excel file of survey data
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