The Effect of Wal-Mart Supercenters on Grocery Prices in New England

This study analyzes the effect of the presence of Wal-Mart Supercenters on the prices at conventional supermarkets in Massachusetts, Connecticut, and Rhode Island. Using price indexes constructed from primary price data on a basket of 54 goods and holding several demographics and market conditions constant, we determine that Supercenters result in a 7.79% average price reduction in national brand goods and a 6.38% average price reduction in private label goods. Wal-Mart Supercenters also price their groceries on average 15.65% lower than supermarkets competing with Supercenters and 22.28% lower than supermarkets geographically distant from Supercenters.Marketing,

Probabilistic Anomaly Detection in Natural Gas Time Series Data

This paper introduces a probabilistic approach to anomaly detection, specifically in natural gas time series data. In the natural gas field, there are various types of anomalies, each of which is induced by a range of causes and sources. The causes of a set of anomalies are examined and categorized, and a Bayesian maximum likelihood classifier learns the temporal structures of known anomalies. Given previously unseen time series data, the system detects anomalies using a linear regression model with weather inputs, after which the anomalies are tested for false positives and classified using a Bayesian classifier. The method can also identify anomalies of an unknown origin. Thus, the likelihood of a data point being anomalous is given for anomalies of both known and unknown origins. This probabilistic anomaly detection method is tested on a reported natural gas consumption data set

Data Improving in Time Series Using ARX and ANN Models

Anomalous data can negatively impact energy forecasting by causing model parameters to be incorrectly estimated. This paper presents two approaches for the detection and imputation of anomalies in time series data. Autoregressive with exogenous inputs (ARX) and artificial neural network (ANN) models are used to extract the characteristics of time series. Anomalies are detected by performing hypothesis testing on the extrema of the residuals, and the anomalous data points are imputed using the ARX and ANN models. Because the anomalies affect the model coefficients, the data cleaning process is performed iteratively. The models are re-learned on “cleaner” data after an anomaly is imputed. The anomalous data are reimputed to each iteration using the updated ARX and ANN models. The ARX and ANN data cleaning models are evaluated on natural gas time series data. This paper demonstrates that the proposed approaches are able to identify and impute anomalous data points. Forecasting models learned on the unclean data and the cleaned data are tested on an uncleaned out-of-sample dataset. The forecasting model learned on the cleaned data outperforms the model learned on the unclean data with 1.67% improvement in the mean absolute percentage errors and a 32.8% improvement in the root mean squared error. Existing challenges include correctly identifying specific types of anomalies such as negative flows

Influence of Rough and Smooth Walls on Macroscale Flows in Tumblers

Walls in discrete element method simulations of granular flows are sometimes modeled as a closely packed monolayer of fixed particles, resulting in a rough wall rather than a geometrically smooth wall. An implicit assumption is that the resulting rough wall differs from a smooth wall only locally at the particle scale. Here we test this assumption by considering the impact of the wall roughness at the periphery of the flowing layer on the flow of monodisperse particles in a rotating spherical tumbler. We find that varying the wall roughness significantly alters average particle trajectories even far from the wall. Rough walls induce greater poleward axial drift of particles near the flowing layer surface, but decrease the curvature of the trajectories. Increasing the volume fill level in the tumbler has little effect on the axial drift for rough walls, but increases the drift while reducing curvature of the particle trajectories for smooth walls. The mechanism for these effects is related to the degree of local slip at the bounding wall, which alters the flowing layer thickness near the walls, affecting the particle trajectories even far from the walls near the equator of the tumbler. Thus, the proper choice of wall conditions is important in the accurate simulation of granular flows, even far from the bounding wall.Comment: 32 pages, 19 figures, regular article, accepted for publication in Physical Review E 200

Applying Organizational Routines in understanding organizational change

Organizational routines are considered basic components of organizational behavior and repositories of Organizational capabilities (Nelson and Winter, 1982). They do, therefore, hold one of the keys to understanding organizational change. We identify problems encountered in such research and present proposal for how to deal with them, in order to advance our knowledge of routines and our understanding or organizational change. Developing these themes, we also introduce the articles in the special section 'Towards an Operationalization of the Routines concept'.

La théorie évolutionniste 20 ans après : une introduction.

Introduction au numéro spécial

La théorie évolutionniste du changement économique de Nelson et Winter : une analyse économique rétrospective

L'objectif de cet article consiste en une évaluation critique de la théorie évolutionniste contemporaine qui s'est développée depuis l'ouvrage fondateur de Nelson et Winter [1982]. Cet ouvrage et cette théorie s'appuient sur les traditions schumpeterienne et simonienne, quitte à renoncer à certaines de leurs hypothèses initiales. Nelson et Winter proposent une critique de "l'orthodoxie contemporaine" et de ses fondements microéconomiques. Ils suggèrent, par ailleurs, un programme de recherche qualifié de génétique organisationnelle qui s'inspire de la biologie. Cette approche a soulevé de nombreuses critiques car il existe une ambiguïté quant au niveau pertinent de sélection des technologies et des routines. La nature même de la création de la connaissance est discutée. Par ailleurs, le rôle des routines dans la téhorie évolutionniste est mis en avant au niveau conceptuel et au plan de la formalisation. Le projet de recherche proposé se caractérise au total par une originalité certaine même si des problèmes liés à la caractérisation des processus de sélection et de mutation existent et font débat au sein de l'évolutionnisme contemporain.

Skaitmeninių įrankių privalumai ir trūkumai siekiant rankraštiniuose laiškuose atkurti XIX amžiaus filosofijos skaitytojų emocijas

This article discusses the limitations and benefits of resorting to digital tools and research methodology to explore nineteenth-century manuscript letters, written by readers to the French philosopher Victor Cousin, and to increase our understanding of how ordinary readers responded to philosophy at the time. More broadly, it examines the potential assets of the annotation interface developed in the Reading Europe Advance Data Investigation Tool (READ-IT https://readit-project.eu/ 2018–2021), a collaborative research project focusing on regenerating lost connections about the cultural heritage of reading from large volumes of highly-diverse eighteenth- to twenty-first-century sources in multiple languages. The case study describes challenges raised by attempts to detect and classify differences between female and male philosophical reading experiences as well as emotional responses, something which is largely under-explored. Along the way it provides reflexive as well as epistemological insights into the promises of big data for research on cultural history and literary archives and the current state of knowledge on emotions.Šiame straipsnyje aptariami skaitmeninių įrankių ir tyrimo metodologijos trūkumai ir pranašumai tyrinėjant XIX amžiaus rankraštinius laiškus, kuriuos skaitytojai rašė prancūzų filosofui Victorui Cousinui, bei siekiant geriau suprasti paprastų skaitytojų reakciją į tuometę filosofiją. Kalbant plačiau, straipsnyje nagrinėjami potencialūs anotacijų sąsajos privalumai, atskleisti bendrame mokslinių tyrimų projekte „Reading Europe Advance Data Investigation Tool“ (READ-IT https://readit-project.eu/, 2018–2021 m.), kuriame pagrindinis dėmesys skiriamas atkurti prarastus ryšius apie skaitymo kultūros paveldą iš daugybės labai įvairių XVIII–XXI amžių šaltinių, skelbiamų keliomis kalbomis. Atvejo tyrime aprašomi iššūkiai, kylantys dėl bandymų aptikti ir tam tikrai kategorijai priskirti skirtumus tarp moterų ir vyrų filosofinio skaitymo patirties bei emocinių reakcijų, o tai iš esmės yra nepakankamai ištirta sritis. Be to, straipsnyje pateikiama refleksyvių ir epistemologinių įžvalgų apie didžiųjų duomenų teikiamas viltis kultūros istorijos ir literatūros archyvų tyrimams bei dabartinę žinių apie emocijas būklę

Fano Resonances in Mid-Infrared Spectra of Single-Walled Carbon Nanotubes

This work revisits the physics giving rise to the carbon nanotubes phonon bands in the mid- infrared. Our measurements of doped and undoped samples of single-walled carbon nanotubes in Fourier transform infrared spectroscopy show that the phonon bands exhibit an asymmetric lineshape and that their effective cross-section is enhanced upon doping. We relate these observations to electron-phonon coupling or, more specifically, to a Fano resonance phenomenon. We note that only the dopant-induced intraband continuum couples to the phonon modes and that defects induced in the sidewall increase the resonance probabilities.Comment: 5 pages, 4 figures and 1 Supplementary Information File (in pdf

MUSCLE FORCE ESTIMATION IN CLINICAL BIOMECHANICS: ANYBODY VS OPENSIM

Knowing the force profiles of individual muscles during various functional tasks may help to better identify various neuro-musculoskeletal impairments from functional movement analysis. Different simulation environments exist for this purpose. The aim of this study was to compare gait muscle force estimations (static optimisation) between the simulation environments AnyBody and OpenSim, using two similar musculoskeletal models. Results show mostly similar muscle forces, while some differences exist, resulting out of different anthropometrics and constraints of the generic models. The findings indicate the necessity to carefully analyse results when comparing muscle force estimations from different simulation environments. Future studies will develop a standardised protocol for such analyses