2,458 research outputs found
An Adaptive Dictionary Learning Approach for Modeling Dynamical Textures
Video representation is an important and challenging task in the computer
vision community. In this paper, we assume that image frames of a moving scene
can be modeled as a Linear Dynamical System. We propose a sparse coding
framework, named adaptive video dictionary learning (AVDL), to model a video
adaptively. The developed framework is able to capture the dynamics of a moving
scene by exploring both sparse properties and the temporal correlations of
consecutive video frames. The proposed method is compared with state of the art
video processing methods on several benchmark data sequences, which exhibit
appearance changes and heavy occlusions
Quitting patterns and success rates of a tobacco cessation program led by New Mexico Pharmaceutical Care Foundation
The objective of the present study was to assess the effectiveness of a pharmacists-assisted tobacco cessation program led by New Mexico Pharmaceutical Care Foundation (NMPCF) and to characterize participants quitting patterns during the study period. Data from the program from 2004 to 2011 consisting of 1486 participants were combined for analysis. Point prevalence quit rates were calculated and survival analysis was performed to evaluate program effectiveness. A qualitative case study with participating pharmacists was conducted to explore intervention elements that could impact participants\u27 likelihood of successfully quitting tobacco. Four quitting patterns were defined including immediate quitters, delayed quitters, once quitters, or never quitters. Multinomial logistic regression was performed to identify patient characteristics associated with quitting patterns. The average point prevalence quit rate at 6 months was 18.7%. The average abstinent time was 76.8 days (standard error = 3.59 days). The probability of a patient being continuously abstinent for 7 days was 89.1%, while the likelihood of being abstinent for 30 days and 180 days were 46.0% and 16.5%, respectively. Patients who were under 18 years old, less educated, less dependent on nicotine, and had higher confidence to quit were more likely to be immediate quitters rather than never quitters. Pharmacists are capable of delivering tobacco cessation services. Patients\u27 likelihood of quitting tobacco depends both on themselves and the intervention they receive. Intensive counseling and close follow-up are important elements of an effective tobacco cessation intervention. Different quitting patterns exist among patients. Patients with different quitting patterns have distinctive characteristics in terms of level of nicotine dependence, pharmacotherapy used, motivational factors and demographic factors. Interventions need to be tailored for patients with different quitting patterns
On the Value of Multistage Risk-Averse Stochastic Facility Location With or Without Prioritization
We consider a multiperiod stochastic capacitated facility location problem
under uncertain demand and budget in each period. Using a scenario tree
representation of the uncertainties, we formulate a multistage stochastic
integer program to dynamically locate facilities in each period and compare it
with a two-stage approach that determines the facility locations up front. In
the multistage model, in each stage, a decision maker optimizes facility
locations and recourse flows from open facilities to demand sites, to minimize
certain risk measures of the cost associated with current facility location and
shipment decisions. When the budget is also uncertain, a popular modeling
framework is to prioritize the candidate sites. In the two-stage model, the
priority list is decided in advance and fixed through all periods, while in the
multistage model, the priority list can change adaptively. In each period, the
decision maker follows the priority list to open facilities according to the
realized budget, and optimizes recourse flows given the realized demand. Using
expected conditional risk measures (ECRMs), we derive tight lower bounds for
the gaps between the optimal objective values of risk-averse multistage models
and their two-stage counterparts in both settings with and without
prioritization. Moreover, we propose two approximation algorithms to
efficiently solve risk-averse two-stage and multistage models without
prioritization, which are asymptotically optimal under an expanding market
assumption. We also design a set of super-valid inequalities for risk-averse
two-stage and multistage stochastic programs with prioritization to reduce the
computational time. We conduct numerical studies using both randomly generated
and real-world instances with diverse sizes, to demonstrate the tightness of
the analytical bounds and efficacy of the approximation algorithms and
prioritization cuts
Link between K-absorption edges and thermodynamic properties of warm-dense plasmas established by improved first-principles method
A precise calculation that translates shifts of X-ray K-absorption edges to
variations of thermodynamic properties allows quantitative characterization of
interior thermodynamic properties of warm dense plasmas by X-ray absorption
techniques, which provides essential information for inertial confinement
fusion and other astrophysical applications. We show that this interpretation
can be achieved through an improved first-principles method. Our calculation
shows that the shift of K-edges exhibits selective sensitivity to thermal
parameters and thus would be a suitable temperature index to warm dense
plasmas. We also show with a simple model that the shift of K-edges can be used
to detect inhomogeneity inside warm dense plasmas when combined with other
experimental tools
Extended First-Principles Molecular Dynamics Method From Cold Materials to Hot Dense Plasmas
An extended first-principles molecular dynamics (FPMD) method based on
Kohn-Sham scheme is proposed to elevate the temperature limit of the FPMD
method in the calculation of dense plasmas. The extended method treats the wave
functions of high energy electrons as plane waves analytically, and thus
expands the application of the FPMD method to the region of hot dense plasmas
without suffering from the formidable computational costs. In addition, the
extended method inherits the high accuracy of the Kohn-Sham scheme and keeps
the information of elec- tronic structures. This gives an edge to the extended
method in the calculation of the lowering of ionization potential, X-ray
absorption/emission spectra, opacity, and high-Z dense plasmas, which are of
particular interest to astrophysics, inertial confinement fusion engineering,
and laboratory astrophysics
- …