Customers’ experiences of fast food delivery services: uncovering the semantic core benefits, actual and augmented product by text mining

Purpose This study conceptualizes food delivery services as service mix decisions (SMDs) and illustrates a data-driven approach for the analysis of customers' written experiences. Design/methodology/approach Web scraping, text mining techniques as well as multivariate statistics are combined to uncover the structure of the three tiers of SMD from consumers' point of view. Findings The analyses reveal that fast food delivery is not primarily about speed but that there are four distinct experiential factors to be considered for SMDs. Fast food delivery services are associated both with the actual product (i.e. product issues and brand satisfaction) and with the augmented product (payment process and service handling). Originality/value Findings demonstrate the relevance of SMDs in omnichannel food retail environments and guide researchers in multistage analyses of consumers' online food reviews

Investigation of Noise and Ride Quality Trends for Asphaltic Pavement Surface Types: Five-Year Results

Field data regarding tire/pavement noise, ride quality, and macrotexture were collected over five consecutive years from pavements in California placed with open-graded and other asphaltic mixes. The five-year data were analyzed to evaluate the ride quality and effectiveness of open-graded mixes in reducing noise compared to other asphalt surfaces, including dense- and gap-graded mixes, and to evaluate the pavement characteristics that affect tire/pavement noise. The analysis in this report is a supplement and update to four previous studies on the first four years of data collected, which are detailed in four separate reports. Models have been updated, with some changes in the use of condition survey variables. Conclusions are made regarding the performance of open-graded mixes and rubberized mixes (RAC-G), comparisons are made with dense-graded mixes (DGAC), and the effects of variables affecting tire/pavement noise are examined. Tire/pavement noise is greatly influenced by surface mix type and mix properties, age, traffic volume, and the presence of stresses indicated by pavement surface macrotexture, which served as a substitute for raveling in this study. Noise levels generally increased primarily with traffic volume and pavement age. Overall noise levels decreased with increased surface layer thickness and permeability (or air-void content)

Effects of Milling and Other Repairs on the Smoothness of Overlays on Asphalt Pavements from 2000 to 2009

The application of asphalt overlays comprises a significant percentage of the maintenance activities undertaken to improve the condition of existing asphalt pavements, and greater attention is now being paid to improving surface smoothness by constructing smoother overlays. The expected benefits of smoother overlays include longer service life due to decreased dynamic loading, improved fuel economy, and greater road-user comfort. In this study, data from the California Department of Transportation (Caltrans) Pavement Condition Survey (PCS) for projects built between 2000 and 2009 were used to investigate the effects of repairs, pavement pre-overlay smoothness (in terms of International Roughness Index, IRI), overlay mix type (dense-graded, gap-graded, open-graded), and binder type (rubberized versus conventional or polymer-modified) on initial post-construction overlay smoothness. The results are based on overlays constructed prior to implementation of the Caltrans smoothness specification for overlay construction. Linear mixed effects models were used in the analysis to take into account the variation across random effect variables. In this study, overlay smoothness was measured in terms of IRI. The analysis results indicated that the pavement pre-overlay IRI was the most important variable affecting overlay smoothness: pavements with lower pre-overlay IRI were smoother than those with higher pre-overlay IRI. When the pre-overlay condition was poor, increasing overlay thickness was also found to have a significant effect on post-overlay smoothness. In terms of pre-overlay repairs, analysis of Caltrans PCS data showed that overlays were smoother when digouts (milling and patching in the wheelpaths) were performed compared with milling of the entire surface prior to the overlay. The effects of overlay mix type and binder type were dependent on the pre-existing pavement condition and/or other factors

Gradient expansion, curvature perturbations and magnetized plasmas

The properties of magnetized plasmas are always investigated under the hypothesis that the relativistic inhomogeneities stemming from the fluid sources and from the geometry itself are sufficiently small to allow for a perturbative description prior to photon decoupling. The latter assumption is hereby relaxed and pre-decoupling plasmas are described within a suitable expansion where the inhomogeneities are treated to a given order in the spatial gradients. It is argued that the (general relativistic) gradient expansion shares the same features of the drift approximation, customarily employed in the description of cold plasmas, so that the two schemes are physically complementary in the large-scale limit and for the low-frequency branch of the spectrum of plasma modes. The two-fluid description, as well as the magnetohydrodynamical reduction, are derived and studied in the presence of the spatial gradients of the geometry. Various solutions of the coupled system of evolution equations in the anti-Newtonian regime and in the quasi-isotropic approximation are presented. The relation of this analysis to the so-called separate Universe paradigm is outlined. The evolution of the magnetized curvature perturbations in the nonlinear regime is addressed for the magnetized adiabatic mode in the plasma frame.Comment: 40 pages, no figure

Evaluation of the Safe Ischemic Time of Clamping During Intermittent Pringles Maneuver in Rabbits

Background: The liver is the most commonly injured organ in blunt abdominal trauma. Although major hepatic bleeding may be partially controlled with portal triade clamping (the Pringle’s maneuver), continuous prolonged clamping results in liver ischemia. Objectives: The purpose of this study was to determine the safe time of Pringle maneuver based on pathologic changes of liver in rabbit models. Materials and Methods: In an experimental study, 20 New-Zealand white rabbits were selected. In laparotomy, a blunt dissector was passed through the foramen of Winslow and the hepato-duodenal ligament encircled with an umbilical tape. En masse Pringle maneuver was performed using atraumatic flexible clamps. Rabbits were divided into four groups based on Pringle maneuver time (30 minutes, 45 minutes, 60 minutes, and 75 minutes). A hepatic biopsy was performed at the beginning of operation. The degree of tissue injury was evaluated using blood markers. Results: There were five rabbits in each group. At the end of 60 minutes ischemia, only minor alterations were observed in pathological specimens. At the end of 75 minutes, hepatocyte damage and necrosis were observed. The serum levels of alanine aminotransferase (Group A: P = 0.02; Group B: P = 0.01; Group C: P = 0.0002; Group D: P = 0.01) and Aspartate aminotransferase (Group A: P = 0.03; Group B: P = 0.002; Group C: P = 0.0004; Group D: P = 0.0003) were significantly increased post-operatively. The maximum level was in the first day after operation. Conclusions: Continuous portal triade clamping (the Pringle maneuver) during liver ischemia (30 and 45 minutes) in rabbits resulted in no ischemic change. Increasing time of clamping to 30 minutes was safe in intermittent Pringle maneuver

Diffeomorphism algebra of two dimensional free massless scalar field with signature change

We study a model of free massless scalar fields on a two dimensional cylinder with metric that admits a change of signature between Lorentzian and Euclidean type (ET), across the two timelike hypersurfaces (with respect to Lorentzian region). Considering a long strip-shaped region of the cylinder, denoted by an angle \theta, as the signature changed region it is shown that the energy spectrum depends on the angle \theta and in a sense differs from ordinary one for low energies. Morever diffeomorphism algebra of corresponding infinite conserved charges is different from '' Virasoro'' algebra and approaches to it at higher energies. The central term is also modified but does not approach to the ordinary one at higher energies.Comment: 18 pages, Latex, 2 ps figure