14,916 research outputs found
Air freight demand models: An overview
A survey is presented of some of the approaches which have been considered in freight demand estimation. The few existing continuous time computer simulations of aviation systems are reviewed, with a view toward the assessment of this approach as a tool for structuring air freight studies and for relating the different components of the air freight system. The variety of available data types and sources, without which the calibration, validation and the testing of both modal split and simulation models would be impossible are also reviewed
Exploration and Exploitation of Victorian Science in Darwin's Reading Notebooks
Search in an environment with an uncertain distribution of resources involves
a trade-off between exploitation of past discoveries and further exploration.
This extends to information foraging, where a knowledge-seeker shifts between
reading in depth and studying new domains. To study this decision-making
process, we examine the reading choices made by one of the most celebrated
scientists of the modern era: Charles Darwin. From the full-text of books
listed in his chronologically-organized reading journals, we generate topic
models to quantify his local (text-to-text) and global (text-to-past) reading
decisions using Kullback-Liebler Divergence, a cognitively-validated,
information-theoretic measure of relative surprise. Rather than a pattern of
surprise-minimization, corresponding to a pure exploitation strategy, Darwin's
behavior shifts from early exploitation to later exploration, seeking unusually
high levels of cognitive surprise relative to previous eras. These shifts,
detected by an unsupervised Bayesian model, correlate with major intellectual
epochs of his career as identified both by qualitative scholarship and Darwin's
own self-commentary. Our methods allow us to compare his consumption of texts
with their publication order. We find Darwin's consumption more exploratory
than the culture's production, suggesting that underneath gradual societal
changes are the explorations of individual synthesis and discovery. Our
quantitative methods advance the study of cognitive search through a framework
for testing interactions between individual and collective behavior and between
short- and long-term consumption choices. This novel application of topic
modeling to characterize individual reading complements widespread studies of
collective scientific behavior.Comment: Cognition pre-print, published February 2017; 22 pages, plus 17 pages
supporting information, 7 pages reference
Codecision and Institutional Change
We examine the sources and processes of institutional change in one important aspect of EU politics-the legislative procedure of codecision and show how interstitial change of institutions emerges between formal Treaty revisions and under specific conditions may be formalized in subsequent formal Treaty reforms. We develop two related models of Treaty change. First, in a 'simple' model, we argue that informal rules will be formalized in the Treaty text where all member states are in agreement, and will be rolled back when all member states oppose them; otherwise they will continue in existence at the informal level. Second, in a more complex framework, we argue that actors who have effective veto powers in a related arena may make credible threats that allow them to press member states into formalizing informal rules, provided that member states are not unanimously opposed to this formalization. We empirically assess our claims in the light of several instances of informal rules applied in the codecision procedure.democracy; European Parliament; European Parliament; co-decision procedure
I, NEURON: the neuron as the collective
Purpose â In the last half-century, individual sensory neurons have been bestowed with characteristics of the whole human being, such as behavior and its oft-presumed precursor, consciousness. This anthropomorphization is pervasive in the literature. It is also absurd, given what we know about neurons, and it needs to be abolished. This study aims to first understand how it happened, and hence why it persists.
Design/methodology/approach â The peer-reviewed sensory-neurophysiology literature extends to hundreds (perhaps thousands) of papers. Here, more than 90 mainstream papers were scrutinized.
Findings â Anthropomorphization arose because single neurons were cast as âobserversâ who âidentifyâ, âcategorizeâ, ârecognizeâ, âdistinguishâ or âdiscriminateâ the stimuli, using math-based algorithms that reduce (âdecodeâ) the stimulus-evoked spike trains to the particular stimuli inferred to elicit them. Without âdecodingâ, there is supposedly no perception. However, âdecodingâ is both unnecessary and unconfirmed. The neuronal âobserverâ in fact consists of the laboratory staff and the greater society that supports them. In anthropomorphization, the neuron becomes the collective.
Research limitations/implications â Anthropomorphization underlies the widespread application to neurons Information Theory and Signal Detection Theory, making both approaches incorrect.
Practical implications â A great deal of time, money and effort has been wasted on anthropomorphic Reductionist approaches to understanding perception and consciousness. Those resources should be diverted into more-fruitful approaches.
Originality/value â A long-overdue scrutiny of sensory-neuroscience literature reveals that anthropomorphization, a form of Reductionism that involves the presumption of single-neuron consciousness, has run amok in neuroscience. Consciousness is more likely to be an emergent property of the brain
Defining and characterising structural uncertainty in decision analytic models
An inappropriate structure for a decision analytic model can potentially invalidate estimates of cost-effectiveness and estimates of the value of further research. However, there are often a number of alternative and credible structural assumptions which can be made. Although it is common practice to acknowledge potential limitations in model structure, there is a lack of clarity about methods to characterize the uncertainty surrounding alternative structural assumptions and their contribution to decision uncertainty. A review of decision models commissioned by the NHS Health Technology Programme was undertaken to identify the types of model uncertainties described in the literature. A second review was undertaken to identify approaches to characterise these uncertainties. The assessment of structural uncertainty has received little attention in the health economics literature. A common method to characterise structural uncertainty is to compute results for each alternative model specification, and to present alternative results as scenario analyses. It is then left to decision maker to assess the credibility of the alternative structures in interpreting the range of results. The review of methods to explicitly characterise structural uncertainty identified two methods: 1) model averaging, where alternative models, with different specifications, are built, and their results averaged, using explicit prior distributions often based on expert opinion and 2) Model selection on the basis of prediction performance or goodness of fit. For a number of reasons these methods are neither appropriate nor desirable methods to characterize structural uncertainty in decision analytic models. When faced with a choice between multiple models, another method can be employed which allows structural uncertainty to be explicitly considered and does not ignore potentially relevant model structures. Uncertainty can be directly characterised (or parameterised) in the model itself. This method is analogous to model averaging on individual or sets of model inputs, but also allows the value of information associated with structural uncertainties to be resolved.
Economics and Corporate Social Responsibility
Corporate Social Responsibility (CSR) is an important economic phenomenon with broad implications for .rms, employees, consumers, investors, governments and NGOs alike. This paper collects, structures and combines scattered pieces of economic theory and empirical evidence in novel ways that shed light on various fundamental economic questions related to CSR. The main conjecture presents individual preferences as the ultimate driving force behind any form of CSR. In the presence of social stakeholder preferences, firms may use strategic CSR to maximize profits, while not-for-profit CSR may satisfy shareholders. social ambitions. Only if managers take CSR beyond strategic levels or shareholder preferences, does CSR constitute moral hazard. Incentives and mechanisms underlying for-profit CSR will be outlined in greater detail. Six frameworks for the analysis of strategic CSR are proposed and analyzed. Finally, some empirical issues related to measurement and estimation of CSR are briefly discussed.Corporate Social Responsibility, Public Goods Provision, Preferences, Strategic CSR
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