Distorted representation in visual tourism research

Tourism research has recently been informed by non-representational theories to highlight the socio-material, embodied and heterogeneous composition of tourist experiences. These advances have contributed to further reflexivity and called for novel ways to animate representations. On this background, this article develops the notion ‘distorted representation’ to illustrate that blurred and obscure photos can in fact be intelligible and sensible in understanding tourism. Through an exploration of the overwhelmed and unintended practices of visual fieldwork, distorted representation illustrates how photographic materialities, performativities and sensations contribute to new tourism knowledges. While highlighting the potential of distorted representation, the article posits a cautionary note in regards to the influential role of academic journals in determining the qualities of visual data. The article exemplifies distorted representation through three impressionistic tales derived from ethnographic research on the European rail travel phenomenon: interrail.     

A Unifying Framework and Comparison of Algorithms for Non-negative Matrix Factorisation

Non-negative matrix factorisation (NMF) is an increasingly popular unsupervised learning method. However, parameter estimation in the NMF model is a difficult high-dimensional optimisation problem. We consider algorithms of the alternating least squares type. Solutions to the least squares problem fall in two categories. The first category is iterative algorithms, which include algorithms such as the majorise–minimise (MM) algorithm, coordinate descent, gradient descent and the Févotte-Cemgil expectation–maximisation (FC-EM) algorithm. We introduce a new family of iterative updates based on a generalisation of the FC-EM algorithm. The coordinate descent, gradient descent and FC-EM algorithms are special cases of this new EM family of iterative procedures. Curiously, we show that the MM algorithm is never a member of our general EM algorithm. The second category is based on cone projection. We describe and prove a cone projection algorithm tailored to the non-negative least square problem. We compare the algorithms on a test case and on the problem of identifying mutational signatures in human cancer. We generally find that cone projection is an attractive choice. Furthermore, in the cancer application, we find that a mix-and-match strategy performs better than running each algorithm in isolation.     

An optimal stopping problem in risk theory

Abstract

In classical risk theory often stationary premium and claim processes are considered. In some cases it is more convenient to model non-stationary processes which describe a movement from environmental conditions, for which the premiums were calculated, to less favorable circumstances. This is done by a Markov-modulated Poisson claim process. Moreover the insurance company is allowed to stop the process at some random time, if the situation seems unfavorable, in order to calculate new premiums. This leads to an optimal stopping problem which is solved explicitly to some extent.     

Spanish Household Demand for Seafood

Seafood is an important food commodity in Spain, the second largest consuming nation of seafood in the world. Today, several changes in demographics, socioeconomic factors, and lifestyle changes have affected demand for seafood products. Double‐hurdle models allow an examination of Spanish household expenditures on these products and explicitly account for the value of women's time. The empirical evidence shows that the set of statistically significant factors in the participation and expenditure equations is not the same for fresh and processed seafood goods. Income and household demographic variables are important determinants of both participation and expenditures on seafood products. In addition, the value of women's time affects expenditures on processed products, which include frozen, cured, and canned seafood goods.     

Saving Rates, Trade, Technology, and Stochastic Dynamics

This paper develops a framework for analyzing the stochastic dynamics of small growing trading economies with CES sector technologies. The open neoclassical two-sector growth model with a diffusion process (uncertainty) for the aggregate saving/investment ratio is demonstrated with sample paths and long-run probability distributions of the overall factor endowment ratio. Stochastic endogenous growth and cycles require a combination of fundamental growth parameter values: saving rates, terms of trade, and sectorial substitution elasticities.     

Time-bound concepts in the catholic social teaching of the 19th and early 20th centuries

This essay has both a general and a specific purpose. Its general purpose is to pose the question: Can neoclassical economics be social economics? Its answer to this general question is: Yes, but only if it abandons its methodological soul; that is, by abandoning methodological individualism, positivism, and ahistoricism, and expressly and systematically adopting a methodological perspective which is holistic, normative, and historical. Its specific purpose is to identify and examine the major elements in the economics of one leading figure in the historical development of neoclassical economics who self-consciously attempted to combine, to paraphrase Schumpeter, a neoclassical head with a social economics heart: Alfred Marshall.     

The effect of mass shootings on the demand for guns

Unfortunately, mass shootings are common occurrences in the United States. When one occurs, it makes national news, becomes fodder for the ongoing national gun debate among politicians and activists, and may impact the demand for guns through fears of violence and future gun regulation. We attempt to estimate the overall effect of mass shootings on gun demand in the United States and how this effect varies across the nation, time, and other factors. Mass shootings are found to increase the national demand for firearms, with the effect lasting up to 2 months. Stronger effects are found in gun-heavy and/or Republican states but not necessarily near where the shooting occurred. Demand spikes are also larger if the shooter was White, female, or if the event took place in a rural setting, but seemingly less related to the specific venue, the shooter's age or known mental health, the number of fatalities, or weapon characteristics.