1,316 research outputs found
Engagement With a Behavior Change App for Alcohol Reduction: Data Visualization for Longitudinal Observational Study
BACKGROUND: Behavior change apps can develop iteratively, where the app evolves into a complex, dynamic, or personalized intervention through cycles of research, development, and implementation. Understanding how existing users engage with an app (eg, frequency, amount, depth, and duration of use) can help guide further incremental improvements. We aim to explore how simple visualizations can provide a good understanding of temporal patterns of engagement, as usage data are often longitudinal and rich. OBJECTIVE: This study aims to visualize behavioral engagement with Drink Less, a behavior change app to help reduce hazardous and harmful alcohol consumption in the general adult population of the United Kingdom. METHODS: We explored behavioral engagement among 19,233 existing users of Drink Less. Users were included in the sample if they were from the United Kingdom; were 18 years or older; were interested in reducing their alcohol consumption; had a baseline Alcohol Use Disorders Identification Test score of 8 or above, indicative of excessive drinking; and had downloaded the app between May 17, 2017, and January 22, 2019 (615 days). Measures of when sessions begin, length of sessions, time to disengagement, and patterns of use were visualized with heat maps, timeline plots, k-modes clustering analyses, and Kaplan-Meier plots. RESULTS: The daily 11 AM notification is strongly associated with a change in engagement in the following hour; reduction in behavioral engagement over time, with 50.00% (9617/19,233) of users disengaging (defined as no use for 7 or more consecutive days) 22 days after download; identification of 3 distinct trajectories of use, namely engagers (4651/19,233, 24.18% of users), slow disengagers (3679/19,233, 19.13% of users), and fast disengagers (10,903/19,233, 56.68% of users); and limited depth of engagement with 85.076% (7,095,348/8,340,005) of screen views occurring within the Self-monitoring and Feedback module. In addition, a peak of both frequency and amount of time spent per session was observed in the evenings. CONCLUSIONS: Visualizations play an important role in understanding engagement with behavior change apps. Here, we discuss how simple visualizations helped identify important patterns of engagement with Drink Less. Our visualizations of behavioral engagement suggest that the daily notification substantially impacts engagement. Furthermore, the visualizations suggest that a fixed notification policy can be effective for maintaining engagement for some users but ineffective for others. We conclude that optimizing the notification policy to target both effectiveness and engagement is a worthwhile investment. Our future goal is to both understand the causal effect of the notification on engagement and further optimize the notification policy within Drink Less by tailoring to contextual circumstances of individuals over time. Such tailoring will be informed from the findings of our micro-randomized trial (MRT), and these visualizations were useful in both gaining a better understanding of engagement and designing the MRT
On the origin of multiple ordered phases in PrFe4P12
The nature of multiple electronic orders in skutterudite PrFe_4P_{12} is
discussed on the basis of a model with antiferro-quadrupole (AFQ) interaction
of \Gamma_3 symmetry. The high-field phase can be reproduced qualitatively
provided (i) ferro-type interactions are introduced between the dipoles as well
as between the octupoles of localized f-electrons, and (ii) separation is
vanishingly small between the \Gamma_1-\Gamma_4^{(1)} crystalline electric
field (CEF) levels. The high-field phase can have either the same ordering
vector q=(1,0,0) as in the low-field phase, or a different one q=0 depending on
the parameters. In the latter case, distortion of the crystal perpendicular to
the (111) axis is predicted. The corresponding anomaly in elastic constants
should also appear. The electrical resistivity is calculated with account of
scattering within the CEF quasi-quartet. It is found that the resistivity as a
function of the direction of magnetic field shows a sharp maximum around the
(111) axis at low temperatures because of the level crossing.Comment: 16 pages, 5 figure
The acheulean handaxe : More like a bird's song than a beatles' tune?
© 2016 Wiley Periodicals, Inc. KV is supported by the Netherlands Organization for Scientific Research. MC is supported by the Canada Research Chairs Program, the Social Sciences and Humanities Research of Canada, the Canada Foundation for Innovation, the British Columbia Knowledge Development Fund, and Simon Fraser UniversityPeer reviewedPublisher PD
Interfacial adsorption phenomena of the three-dimensional three-state Potts model
We study the interfacial adsorption phenomena of the three-state
ferromagnetic Potts model on the simple cubic lattice by the Monte Carlo
method. Finite-size scaling analyses of the net-adsorption yield the evidence
of the phase transition being of first-order and .Comment: 14 page
Structure Factors and Their Distributions in Driven Two-Species Models
We study spatial correlations and structure factors in a three-state
stochastic lattice gas, consisting of holes and two oppositely ``charged''
species of particles, subject to an ``electric'' field at zero total charge.
The dynamics consists of two nearest-neighbor exchange processes, occuring on
different times scales, namely, particle-hole and particle-particle exchanges.
Using both, Langevin equations and Monte Carlo simulations, we study the
steady-state structure factors and correlation functions in the disordered
phase, where density profiles are homogeneous. In contrast to equilibrium
systems, the average structure factors here show a discontinuity singularity at
the origin. The associated spatial correlation functions exhibit intricate
crossovers between exponential decays and power laws of different kinds. The
full probability distributions of the structure factors are universal
asymmetric exponential distributions.Comment: RevTex, 18 pages, 4 postscript figures included, mistaken half-empty
page correcte
Proposal for a CFT interpretation of Watts' differential equation for percolation
G. M. T. Watts derived that in two dimensional critical percolation the
crossing probability Pi_hv satisfies a fifth order differential equation which
includes another one of third order whose independent solutions describe the
physically relevant quantities 1, Pi_h, Pi_hv.
We will show that this differential equation can be derived from a level
three null vector condition of a rational c=-24 CFT and motivate how this
solution may be fitted into known properties of percolation.Comment: LaTeX, 20p, added references, corrected typos and additional content
Effect of Oscillating Landau Bandwidth on the Integer Quantum Hall Effect in a Unidirectional Lateral Superlattice
We have measured activation gaps for odd-integer quantum Hall states in a
unidirectional lateral superlattice (ULSL) -- a two-dimensional electron gas
(2DEG) subjected to a unidirectional periodic modulation of the electrostatic
potential. By comparing the activation gaps with those simultaneously measured
in the adjacent section of the same 2DEG sample without modulation, we find
that the gaps are reduced in the ULSL by an amount corresponding to the width
acquired by the Landau levels through the introduction of the modulation. The
decrement of the activation gap varies with the magnetic field following the
variation of the Landau bandwidth due to the commensurability effect. Notably,
the decrement vanishes at the flat band conditions.Comment: 7 pages, 6 figures, minor revisio
Correct quantum chemistry in a minimal basis from effective Hamiltonians
We describe how to create ab-initio effective Hamiltonians that qualitatively
describe correct chemistry even when used with a minimal basis. The
Hamiltonians are obtained by folding correlation down from a large parent basis
into a small, or minimal, target basis, using the machinery of canonical
transformations. We demonstrate the quality of these effective Hamiltonians to
correctly capture a wide range of excited states in water, nitrogen, and
ethylene, and to describe ground and excited state bond-breaking in nitrogen
and the chromium dimer, all in small or minimal basis sets
The effect of oscillating Fermi energy on the line shape of the Shubnikov-de Haas oscillation in a two dimensional electron gas
The line shape of the Shubnikov-de Haas (SdH) oscillation has been analyzed
in detail for a GaAs/AlGaAs two-dimensional electron gas. The line shape, or
equivalently the behavior of the Fourier components, of the experimentally
observed SdH oscillation is well reproduced by the sinusoidal density of states
at the Fermi energy that oscillates with a magnetic field in a saw-tooth shape
to keep the electron density constant. This suggests that the broadening of
each Landau level by disorder is better described by a Gaussian than by a
Lorentzian.Comment: 7 pages,6 figures, minor revision
Cooperative folding of intrinsically disordered domains drives assembly of a strong elongated protein
Bacteria exploit surface proteins to adhere to other bacteria, surfaces and host cells. Such proteins need to project away from the bacterial surface and resist significant mechanical forces. SasG is a protein that forms extended fibrils on the surface of Staphylococcus aureus and promotes host adherence and biofilm formation. Here we show that although monomeric and lacking covalent cross-links, SasG maintains a highly extended conformation in solution. This extension is mediated through obligate folding cooperativity of the intrinsically disordered E domains that couple non-adjacent G5 domains thermodynamically, forming interfaces that are more stable than the domains themselves. Thus, counterintuitively, the elongation of the protein appears to be dependent on the inherent instability of its domains. The remarkable mechanical strength of SasG arises from tandemly arrayed 'clamp' motifs within the folded domains. Our findings reveal an elegant minimal solution for the assembly of monomeric mechano-resistant tethers of variable length
- …