Characterizing Human Mobility Patterns in a Large Street Network

Previous studies demonstrated empirically that human mobility exhibits Levy flight behaviour. However, our knowledge of the mechanisms governing this Levy flight behaviour remains limited. Here we analyze over 72 000 people's moving trajectories, obtained from 50 taxicabs during a six-month period in a large street network, and illustrate that the human mobility pattern, or the Levy flight behaviour, is mainly attributed to the underlying street network. In other words, the goal-directed nature of human movement has little effect on the overall traffic distribution. We further simulate the mobility of a large number of random walkers, and find that (1) the simulated random walkers can reproduce the same human mobility pattern, and (2) the simulated mobility rate of the random walkers correlates pretty well (an R square up to 0.87) with the observed human mobility rate.Comment: 13 figures, 17 page

The Inter-Store Mobility of Supermarket Shoppers

The allegiance of a particular customer, and the distribution across customers of strength of affiliation to a store are important indicators of store health. It is therefore important to understand the extent and determinants of shopper mobility among competing retailers. While shoppers often patronize many stores, they typically have a primary affiliation to a “main store” that captures the majority of their purchases. We examine, in detail, the tendencies of shoppers to transition away from the current main store and adopt another in its place. That is, rather than study all types of store switching behavior, we focus on the decision to change primary allegiance. The model is established in a discrete time hazard framework and estimated as random-effects probit. Data from 548 households taking 88,945 shopping trips among five stores are used to calibrate the model. We find that state dependence is prevalent with nearly three quarters of the shoppers showing progressive attachment to their current main store. Interestingly, this finding is not simply driven by location (i.e., because shoppers are captive to a single store based on geographical distance). More likely, shoppers are unwilling to give up the benefits of store-specific knowledge of assortment, layout and prices. Second, the decision to transition from a current main store is not influenced by temporary price promotions on a common basket of items: Shoppers will cherry-pick, but this alone does not cause them to change primary allegiance. The majority of transitions occur across competing stores of the same price format, which suggests “format loyalty” is an important aspect of shopper behavior. After controlling for unobserved heterogeneity, we find little relationship between observable demographics and the transition probability. We do, however, find that shoppers who spend more per trip are less likely to change main stores, as are less frequent shoppers. Implications for retail management strategy are discussed

NaAlSi: a self-doped semimetallic superconductor with free electrons and covalent holes

The layered ternary sp conductor NaAlSi, possessing the iron-pnictide "111" crystal structure, superconducts at 7 K. Using density functional methods, we show that this compound is an intrinsic (self-doped) low-carrier-density semimetal with a number of unusual features. Covalent Al-Si valence bands provide the holes, and free-electron-like Al 3s bands, which propagate in the channel between the neighboring Si layers, dip just below the Fermi level to create the electron carriers. The Fermi level (and therefore the superconducting carriers) lies in a narrow and sharp peak within a pseudogap in the density of states. The small peak arises from valence bands which are nearly of pure Si, quasi-two-dimensional, flat, and coupled to Al conduction bands. Isostructural NaAlGe, which is not superconducting above 1.6 K, has almost exactly the same band structure except for one missing piece of small Fermi surface. Certain deformation potentials induced by Si and Na displacements along the c-axis are calculated and discussed. It seems likely that the mechanism of pairing is related to that of several other lightly doped two-dimensional nonmagnetic semiconductors (TiNCl, ZrNCl, HfNCl), which is not well understood but apparently not of phonon origin.Comment: 9 pages, 7 figures, 1 tabl

The Ellipticity and Orientation of Clusters of Galaxies from N-Body Experiments

In this study we use simulations of 128$^3$ particles to study the ellipticity and orientation of clusters of galaxies in N-body simulations of differing power-law initial spectra (P(k) \propto k^n ,n = +1, 0, -1, -2$), and density parameters ($\Omega_0 = 0.2$to 1.0). Furthermore, unlike most theoretical studies we mimic most observers by removing all particles which lie at distances greater than 2 1/h Mpc from the cluster center of mass. We computed the axial ratio and the principal axes using the inertia tensor of each cluster. The mean ellipticity of clusters increases strongly with increasing$n$. We also find that clusters tend to become more spherical at smaller radii. We compared the orientation of a cluster to the orientation of neighboring clusters as a function of distance (correlation). In addition, we considered whether a cluster's major axis tends to lie along the line connecting it to a neighboring cluster, as a function of distance (alignment). Both alignments and correlations were computed in three dimensions and in projection to mimic observational surveys. Our results show that significant alignments exist for all spectra at small separations ($D < 15 h^{-1}$Mpc) but drops off at larger distance in a strongly$n-$dependent way.Comment: 22 pages, requires aaspp4.sty, flushrt.sty, and epsf.sty Revised manuscript, accepted for publication in Ap

Meta-analyze dichotomous data: Do the calculations with Log Odds Ratios and report Risk Ratios or Risk Differences

This paper describes a method to convert meta-analytic results in (log) Odds Ratio to either Risk Ratio or Risk Difference. It has been argued that odds ratios are mathematically superior for meta-analysis, but risk ratios and risk differences are shown to be easier to interpret. Therefore, the proposed method enables the calculation of meta-analytic results in (log) odds ratio and to transform them afterwards in risk ratio and risk difference. This transformation is based on the assumption of equal significance of the results. It is implemented Meta-Essentials: Workbooks for meta-analyses

Role of appetitive phenotype trajectory groups on child body weight during a family-based treatment for children with overweight or obesity.

ObjectiveEmerging evidence suggests that individual appetitive traits may usefully explain patterns of weight loss in behavioral weight loss treatments for children. The objective of this study was to identify trajectories of child appetitive traits and the impact on child weight changes over time.MethodsSecondary data analyses of a randomized noninferiority trial conducted between 2011 and 2015 evaluated children's appetitive traits and weight loss. Children with overweight and obesity (mean age = 10.4; mean BMI z = 2.0; 67% girls; 32% Hispanic) and their parent (mean age = 42.9; mean BMI = 31.9; 87% women; 31% Hispanic) participated in weight loss programs and completed assessments at baseline, 3, 6,12, and 24 months. Repeated assessments of child appetitive traits, including satiety responsiveness, food responsiveness and emotional eating, were used to identify parsimonious grouping of change trajectories. Linear mixed-effects models were used to identify the impact of group trajectory on child BMIz change over time.ResultsOne hundred fifty children and their parent enrolled in the study. The three-group trajectory model was the most parsimonious and included a high satiety responsive group (HighSR; 47.4%), a high food responsive group (HighFR; 34.6%), and a high emotional eating group (HighEE; 18.0%). Children in all trajectories lost weight at approximately the same rate during treatment, however, only the HighSR group maintained their weight loss during follow-ups, while the HighFR and HighEE groups regained weight (adjusted p-value &lt; 0.05).ConclusionsDistinct trajectories of child appetitive traits were associated with differential weight loss maintenance. Identified high-risk subgroups may suggest opportunities for targeted intervention and maintenance programs

Smartphone guide to asthma self-management ages 5 to adult (patient education materials)

This free, colorful, interactive, and evidence-based PDF is designed to support online or in-person education about asthma, with formatting that is smartphone friendly. The patient teaching guide covers key content of asthma self-management education in 15 single-page mini-modules. Help your patients to understand what really asthma is, how uncontrolled asthma scars the lungs, different types of asthma medications, and how to use them correctly. Also includes a customizable action plan and a patient friendly asthma attack algorithm. Text it, email it, fill it in and make it your own! English Version. References: Mammen JR, Rhee H, Atis S, Grape A. Changes in asthma self-management knowledge in inner city adolescents following developmentally sensitive self-management training. Patient Education & Counseling 2018;101:687-95. Mammen JR, Java JJ, Halterman J, et al. Development and preliminary results of an Electronic Medical Record (EMR)-integrated smartphone telemedicine program to deliver asthma care remotely. J Telemed Telecare 2019;0:1-14 Mammen JR, Schoonmaker JD, Java JJ, et al. Going mobile with primary care: Smartphone-telemedicine for asthma management in young urban adults (TEAMS). . Journal of Asthma 2020;0. PLEASE NOTE: This form does not work in Safari and may be corrupted by Safari download. Please use Google Chrome or other browser to access and download