Production inventory policies for defective items with inspection errors, sales return, imperfect rework process and backorders

NASA Astrophysics Data System (ADS)

Jaggi, Chandra K.; Khanna, Aditi; Kishore, Aakanksha

2016-03-01

In order to sustain the challenges of maintaining good quality and perfect screening process, rework process becomes a rescue to compensate for the imperfections present in the production system. The proposed model attempts to explore the existing real-life situation with a more practical approach by incorporating the concept of imperfect rework as this occurs as an unavoidable problem to the firm due to irreparable disorders even in the reworked items. Hence, a production inventory model is formulated here to study the combined effect of imperfect quality items, faulty inspection process and imperfect rework process on the optimal production quantity and optimal backorder level. An analytical method is employed to maximize the expected total profit per unit time. Moreover, the results of several previous research articles namely Chiu et al (2006), Chiu et al (2005), Salameh and Hayek (2001), and classical EPQ with shortages are deduced as special cases. To demonstrate the applicability of the model, and to observe the effects of key parameters on the optimal replenishment policy, a numerical example along with a comprehensive sensitivity analysis has been presented. The pertinence of the model can be found in most of the manufacturing industries like textile, electronics, furniture, footwear, plastics etc. A production lot size model has been explored for defectives items with inspection errors and an imperfect rework process.

Detection and inpainting of facial wrinkles using texture orientation fields and Markov random field modeling.

PubMed

Batool, Nazre; Chellappa, Rama

2014-09-01

Facial retouching is widely used in media and entertainment industry. Professional software usually require a minimum level of user expertise to achieve the desirable results. In this paper, we present an algorithm to detect facial wrinkles/imperfection. We believe that any such algorithm would be amenable to facial retouching applications. The detection of wrinkles/imperfections can allow these skin features to be processed differently than the surrounding skin without much user interaction. For detection, Gabor filter responses along with texture orientation field are used as image features. A bimodal Gaussian mixture model (GMM) represents distributions of Gabor features of normal skin versus skin imperfections. Then, a Markov random field model is used to incorporate the spatial relationships among neighboring pixels for their GMM distributions and texture orientations. An expectation-maximization algorithm then classifies skin versus skin wrinkles/imperfections. Once detected automatically, wrinkles/imperfections are removed completely instead of being blended or blurred. We propose an exemplar-based constrained texture synthesis algorithm to inpaint irregularly shaped gaps left by the removal of detected wrinkles/imperfections. We present results conducted on images downloaded from the Internet to show the efficacy of our algorithms.

Teaching Imperfect Competition at the Principles Level.

ERIC Educational Resources Information Center

Weber, William V.; Highfill, Jannett K.

1990-01-01

Argues that, although most economics textbooks' explanations of imperfect competition may involve three to five models, the concept can be taught using a single, simple model. Uses several business/economic examples as illustrations. (DB)

Imperfection sensitivity of pressured buckling of biopolymer spherical shells

NASA Astrophysics Data System (ADS)

Zhang, Lei; Ru, C. Q.

2016-06-01

Imperfection sensitivity is essential for mechanical behavior of biopolymer shells [such as ultrasound contrast agents (UCAs) and spherical viruses] characterized by high geometric heterogeneity. In this work, an imperfection sensitivity analysis is conducted based on a refined shell model recently developed for spherical biopolymer shells of high structural heterogeneity and thickness nonuniformity. The influence of related parameters (including the ratio of radius to average shell thickness, the ratio of transverse shear modulus to in-plane shear modulus, and the ratio of effective bending thickness to average shell thickness) on imperfection sensitivity is examined for pressured buckling. Our results show that the ratio of effective bending thickness to average shell thickness has a major effect on the imperfection sensitivity, while the effect of the ratio of transverse shear modulus to in-plane shear modulus is usually negligible. For example, with physically realistic parameters for typical imperfect spherical biopolymer shells, the present model predicts that actual maximum external pressure could be reduced to as low as 60% of that of a perfect UCA spherical shell or 55%-65% of that of a perfect spherical virus shell, respectively. The moderate imperfection sensitivity of spherical biopolymer shells with physically realistic imperfection is largely attributed to the fact that biopolymer shells are relatively thicker (defined by smaller radius-to-thickness ratio) and therefore practically realistic imperfection amplitude normalized by thickness is very small as compared to that of classical elastic thin shells which have much larger radius-to-thickness ratio.

The effect of reminder systems on patients’ adherence to treatment

PubMed Central

Fenerty, Sarah D; West, Cameron; Davis, Scott A; Kaplan, Sebastian G; Feldman, Steven R

2012-01-01

Background Patient adherence is an important component of the treatment of chronic disease. An understanding of patient adherence and its modulating factors is necessary to correctly interpret treatment efficacy and barriers to therapeutic success. Purpose This meta-analysis aims to systematically review published randomized controlled trials of reminder interventions to assist patient adherence to prescribed medications. Methods A Medline search was performed for randomized controlled trials published between 1968 and June 2011, which studied the effect of reminder-based interventions on adherence to self-administered daily medications. Results Eleven published randomized controlled trials were found between 1999 and 2009 which measured adherence to a daily medication in a group receiving reminder interventions compared to controls receiving no reminders. Medication adherence was measured as the number of doses taken compared to the number prescribed within a set period of time. Meta- analysis showed a statistically significant increase in adherence in groups receiving a reminder intervention compared to controls (66.61% versus 54.71%, 95% CI for mean: 0.8% to 22.4%). Self-reported and electronically monitored adherence rates did not significantly differ (68.04% versus 63.67%, P = 1.0). Eight of eleven studies showed a statistically significant increase in adherence for at least one of the reminder group arms compared to the control groups receiving no reminder intervention. Limitations The data are limited by imperfect measures of adherence due to variability in data collection methods. It is also likely that concomitant educational efforts in the study populations, such as instructions regarding proper administration and importance of correct dosing schedules, contributed to improved patient adherence, both in reminder and control arms. The search strategy could have missed relevant studies which were categorized by disease rather than adherence. Conclusions Reminder-based interventions may improve adherence to daily medications. However, the interventions used in these studies, which included reminder phone calls, text messages, pagers, interactive voice response systems, videotelephone calls, and programmed electronic audiovisual reminder devices, are impractical for widespread implementation, and their efficacy may be optimized when combined with alternative adherence-modifying strategies. More practical reminder-based interventions should be assessed to determine their value in improving patient adherence and treatment outcomes. PMID:22379363

Breaking the barrier: the Health Belief Model and patient perceptions regarding contraception.

PubMed

Brown, Wendy; Ottney, Anne; Nguyen, Sammie

2011-05-01

The study was conducted to determine the discrepancy between unintended pregnancies and use of contraception is attributed to imperfect use, misconceptions and an inability to adjust therapy to lifestyle. A survey administered at a Federal clinic incorporated the Health Belief Model to determine patient's emphasis in pregnancy prevention. Analysis focused on comparing participant demographics to reasons for contraceptive selection. Ease of use ranked the most important for contraception as patient's education levels increased (p=.001). As household income increased, emphasis on potential side effects became less (p=.02). Patients with private insurance ranked ease of use most frequently (p=.01). Males emphasized effectiveness and menstrual suppression more than females (p=.04 and .008). A positive correlation between perceived benefit regarding ease of use as educational level increased and perceived barriers due to side effects as income level decreased immerged. Special counseling by practitioners to improve patient's self-efficacy, ultimately enhancing contraceptive adherence, are warranted. Copyright © 2011 Elsevier Inc. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saha, Sourabh K.

Although geometric imperfections have a detrimental effect on buckling, imperfection sensitivity has not been well studied in the past during design of sinusoidal micro and nano-scale structures via wrinkling of supported thin films. This is likely because one is more interested in predicting the shape/size of the resultant patterns than the buckling bifurcation onset strain during fabrication of such wrinkled structures. Herein, I have demonstrated that even modest geometric imperfections alter the final wrinkled mode shapes via the mode locking phenomenon wherein the imperfection mode grows in exclusion to the natural mode of the system. To study the effect ofmore » imperfections on mode locking, I have (i) developed a finite element mesh perturbation scheme to generate arbitrary geometric imperfections in the system and (ii) performed a parametric study via finite element methods to link the amplitude and period of the sinusoidal imperfections to the observed wrinkle mode shape and size. Based on this, a non-dimensional geometric parameter has been identified that characterizes the effect of imperfection on the mode locking phenomenon – the equivalent imperfection size. An upper limit for this equivalent imperfection size has been identified via a combination of analytical and finite element modeling. During compression of supported thin films, the system gets “locked” into the imperfection mode if its equivalent imperfection size is above this critical limit. For the polydimethylsiloxane/glass bilayer with a wrinkle period of 2 µm, this mode lock-in limit corresponds to an imperfection amplitude of 32 nm for an imperfection period of 5 µm and 8 nm for an imperfection period of 0.8 µm. Interestingly, when the non-dimensional critical imperfection size is scaled by the bifurcation onset strain, the scaled critical size depends solely on the ratio of the imperfection to natural periods. Furthermore, the computational data generated here can be generalized beyond the specific natural periods and bilayer systems studied to enable deterministic design of a variety of wrinkled micro and nano-scale structures.« less

Active buckling control of an imperfect beam-column with circular cross-section using piezo-elastic supports and integral LQR control

NASA Astrophysics Data System (ADS)

Schaeffner, Maximilian; Platz, Roland

2016-09-01

For slender beam-columns loaded by axial compressive forces, active buckling control provides a possibility to increase the maximum bearable axial load above that of a purely passive structure. In this paper, the potential of active buckling control of an imperfect beam-column with circular cross-section using piezo-elastic supports is investigated numerically. Imperfections are given by an initial deformation of the beam-column caused by a constant imperfection force. With the piezo-elastic supports, active bending moments in arbitrary directions orthogonal to the beam-column's longitudinal axis can be applied at both beam- column's ends. The imperfect beam-column is loaded by a gradually increasing axial compressive force resulting in a lateral deformation of the beam-column. First, a finite element model of the imperfect structure for numerical simulation of the active buckling control is presented. Second, an integral linear-quadratic regulator (LQR) that compensates the deformation via the piezo-elastic supports is derived for a reduced modal model of the ideal beam-column. With the proposed active buckling control it is possible to stabilize the imperfect beam-column in arbitrary lateral direction for axial loads above the theoretical critical buckling load and the maximum bearable load of the passive structure.

Sensitivity of the mode locking phenomenon to geometric imperfections during wrinkling of supported thin films

DOE PAGES

Saha, Sourabh K.

2017-01-11

Although geometric imperfections have a detrimental effect on buckling, imperfection sensitivity has not been well studied in the past during design of sinusoidal micro and nano-scale structures via wrinkling of supported thin films. This is likely because one is more interested in predicting the shape/size of the resultant patterns than the buckling bifurcation onset strain during fabrication of such wrinkled structures. Herein, I have demonstrated that even modest geometric imperfections alter the final wrinkled mode shapes via the mode locking phenomenon wherein the imperfection mode grows in exclusion to the natural mode of the system. To study the effect ofmore » imperfections on mode locking, I have (i) developed a finite element mesh perturbation scheme to generate arbitrary geometric imperfections in the system and (ii) performed a parametric study via finite element methods to link the amplitude and period of the sinusoidal imperfections to the observed wrinkle mode shape and size. Based on this, a non-dimensional geometric parameter has been identified that characterizes the effect of imperfection on the mode locking phenomenon – the equivalent imperfection size. An upper limit for this equivalent imperfection size has been identified via a combination of analytical and finite element modeling. During compression of supported thin films, the system gets “locked” into the imperfection mode if its equivalent imperfection size is above this critical limit. For the polydimethylsiloxane/glass bilayer with a wrinkle period of 2 µm, this mode lock-in limit corresponds to an imperfection amplitude of 32 nm for an imperfection period of 5 µm and 8 nm for an imperfection period of 0.8 µm. Interestingly, when the non-dimensional critical imperfection size is scaled by the bifurcation onset strain, the scaled critical size depends solely on the ratio of the imperfection to natural periods. Furthermore, the computational data generated here can be generalized beyond the specific natural periods and bilayer systems studied to enable deterministic design of a variety of wrinkled micro and nano-scale structures.« less

Remaining useful life prediction of degrading systems subjected to imperfect maintenance: Application to draught fans

NASA Astrophysics Data System (ADS)

Wang, Zhao-Qiang; Hu, Chang-Hua; Si, Xiao-Sheng; Zio, Enrico

2018-02-01

Current degradation modeling and remaining useful life prediction studies share a common assumption that the degrading systems are not maintained or maintained perfectly (i.e., to an as-good-as new state). This paper concerns the issues of how to model the degradation process and predict the remaining useful life of degrading systems subjected to imperfect maintenance activities, which can restore the health condition of a degrading system to any degradation level between as-good-as new and as-bad-as old. Toward this end, a nonlinear model driven by Wiener process is first proposed to characterize the degradation trajectory of the degrading system subjected to imperfect maintenance, where negative jumps are incorporated to quantify the influence of imperfect maintenance activities on the system's degradation. Then, the probability density function of the remaining useful life is derived analytically by a space-scale transformation, i.e., transforming the constructed degradation model with negative jumps crossing a constant threshold level to a Wiener process model crossing a random threshold level. To implement the proposed method, unknown parameters in the degradation model are estimated by the maximum likelihood estimation method. Finally, the proposed degradation modeling and remaining useful life prediction method are applied to a practical case of draught fans belonging to a kind of mechanical systems from steel mills. The results reveal that, for a degrading system subjected to imperfect maintenance, our proposed method can obtain more accurate remaining useful life predictions than those of the benchmark model in literature.

Multilayer multiferroic composites with imperfect interfaces

NASA Astrophysics Data System (ADS)

Kuo, Hsin-Yi; Wu, Tien-Jung; Pan, Ernian

2018-07-01

We study the macroscopic behaviors of multilayered multiferroic composites with interface imperfections by a direct micromechanical approach. Both generalized interface stress type and generalized linear spring type imperfect interfaces are considered. Concise matrix expressions of the overall behaviors of the layered piezoelectric–piezomagnetic composite with contact imperfection are presented. The key step is to observe that the two types of imperfect interface conditions are equivalent to the perfect ones due to the laminated geometry. Numerical calculations are demonstrated for BaTiO3–CoFe2O4 multilayer media, and are shown in good agreement with the more involved interphase model. Furthermore, it is observed that the interface imperfection would reduce the magnitude of the magnetoelectric voltage coefficients as compared to the corresponding perfect interface case. This feature is opposite to that predicted and observed in the corresponding cylindrical composites.

Geometrical optics analysis of the structural imperfection of retroreflection corner cubes with a nonlinear conjugate gradient method.

PubMed

Kim, Hwi; Min, Sung-Wook; Lee, Byoungho

2008-12-01

Geometrical optics analysis of the structural imperfection of retroreflection corner cubes is described. In the analysis, a geometrical optics model of six-beam reflection patterns generated by an imperfect retroreflection corner cube is developed, and its structural error extraction is formulated as a nonlinear optimization problem. The nonlinear conjugate gradient method is employed for solving the nonlinear optimization problem, and its detailed implementation is described. The proposed method of analysis is a mathematical basis for the nondestructive optical inspection of imperfectly fabricated retroreflection corner cubes.

Postbuckling analysis of shear deformable composite flat panels taking into account geometrical imperfections

NASA Technical Reports Server (NTRS)

Librescu, L.; Stein, M.

1990-01-01

The effects of initial geometrical imperfections on the postbuckling response of flat laminated composite panels to uniaxial and biaxial compressive loading are investigated analytically. The derivation of the mathematical model on the basis of first-order transverse shear deformation theory is outlined, and numerical results for perfect and imperfect, single-layer and three-layer square plates with free-free, clamped-clamped, or free-clamped edges are presented in graphs and briefly characterized. The present approach is shown to be more accurate than analyses based on the classical Kirchhoff plate model.

Healthy imperfect dark matter from effective theory of mimetic cosmological perturbations

NASA Astrophysics Data System (ADS)

Hirano, Shin'ichi; Nishi, Sakine; Kobayashi, Tsutomu

2017-07-01

We study the stability of a recently proposed model of scalar-field matter called mimetic dark matter or imperfect dark matter. It has been known that mimetic matter with higher derivative terms suffers from gradient instabilities in scalar perturbations. To seek for an instability-free extension of imperfect dark matter, we develop an effective theory of cosmological perturbations subject to the constraint on the scalar field's kinetic term. This is done by using the unifying framework of general scalar-tensor theories based on the ADM formalism. We demonstrate that it is indeed possible to construct a model of imperfect dark matter which is free from ghost and gradient instabilities. As a side remark, we also show that mimetic F(Script R) theory is plagued with the Ostrogradsky instability.

Predator cognition permits imperfect coral snake mimicry.

PubMed

Kikuchi, David W; Pfennig, David W

2010-12-01

Batesian mimicry is often imprecise. An underexplored explanation for imperfect mimicry is that predators might not be able to use all dimensions of prey phenotype to distinguish mimics from models and thus permit imperfect mimicry to persist. We conducted a field experiment to test whether or not predators can distinguish deadly coral snakes (Micrurus fulvius) from nonvenomous scarlet kingsnakes (Lampropeltis elapsoides). Although the two species closely resemble one another, the order of colored rings that encircle their bodies differs. Despite this imprecise mimicry, we found that L. elapsoides that match coral snakes in other respects are not under selection to match the ring order of their model. We suggest that L. elapsoides have evolved only those signals necessary to deceive predators. Generally, imperfect mimicry might suffice if it exploits limitations in predator cognitive abilities.

Effects of imperfect mixing on low-density polyethylene reactor dynamics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Villa, C.M.; Dihora, J.O.; Ray, W.H.

1998-07-01

Earlier work considered the effect of feed conditions and controller configuration on the runaway behavior of LDPE autoclave reactors assuming a perfectly mixed reactor. This study provides additional insight on the dynamics of such reactors by using an imperfectly mixed reactor model and bifurcation analysis to show the changes in the stability region when there is imperfect macroscale mixing. The presence of imperfect mixing substantially increases the range of stable operation of the reactor and makes the process much easier to control than for a perfectly mixed reactor. The results of model analysis and simulations are used to identify somemore » of the conditions that lead to unstable reactor behavior and to suggest ways to avoid reactor runaway or reactor extinction during grade transitions and other process operation disturbances.« less

Bayesian imperfect information analysis for clinical recurrent data

PubMed Central

Chang, Chih-Kuang; Chang, Chi-Chang

2015-01-01

In medical research, clinical practice must often be undertaken with imperfect information from limited resources. This study applied Bayesian imperfect information-value analysis to realistic situations to produce likelihood functions and posterior distributions, to a clinical decision-making problem for recurrent events. In this study, three kinds of failure models are considered, and our methods illustrated with an analysis of imperfect information from a trial of immunotherapy in the treatment of chronic granulomatous disease. In addition, we present evidence toward a better understanding of the differing behaviors along with concomitant variables. Based on the results of simulations, the imperfect information value of the concomitant variables was evaluated and different realistic situations were compared to see which could yield more accurate results for medical decision-making. PMID:25565853

A Mechanics Model for Sensors Imperfectly Bonded to the Skin for Determination of the Young's Moduli of Epidermis and Dermis.

PubMed

Yuan, J H; Shi, Y; Pharr, M; Feng, X; Rogers, John A; Huang, Yonggang

2016-08-01

A mechanics model is developed for the encapsulated piezoelectric thin-film actuators/sensors system imperfectly bonded to the human skin to simultaneously determine the Young's moduli of the epidermis and dermis as well as the thickness of epidermis.

Modeling Imperfect Generator Behavior in Power System Operation Models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krad, Ibrahim

A key component in power system operations is the use of computer models to quickly study and analyze different operating conditions and futures in an efficient manner. The output of these models are sensitive to the data used in them as well as the assumptions made during their execution. One typical assumption is that generators and load assets perfectly follow operator control signals. While this is a valid simulation assumption, generators may not always accurately follow control signals. This imperfect response of generators could impact cost and reliability metrics. This paper proposes a generator model that capture this imperfect behaviormore » and examines its impact on production costs and reliability metrics using a steady-state power system operations model. Preliminary analysis shows that while costs remain relatively unchanged, there could be significant impacts on reliability metrics.« less

Summary of Research Report

NASA Technical Reports Server (NTRS)

Elishakoff, Isaac

1998-01-01

Ten papers, published in various publications, on buckling, and the effects of imperfections on various structures are presented. These papers are: (1) Buckling mode localization in elastic plates due to misplacement in the stiffner location; (2) On vibrational imperfection sensitivity on Augusti's model structure in the vicinity of a non-linear static state; (3) Imperfection sensitivity due to elastic moduli in the Roorda Koiter frame; (4) Buckling mode localization in a multi-span periodic structure with a disorder in a single span; (5) Prediction of natural frequency and buckling load variability due to uncertainty in material properties by convex modeling; (6) Derivation of multi-dimensional ellipsoidal convex model for experimental data; (7) Passive control of buckling deformation via Anderson localization phenomenon; (8)Effect of the thickness and initial im perfection on buckling on composite cylindrical shells: asymptotic analysis and numerical results by BOSOR4 and PANDA2; (9) Worst case estimation of homology design by convex analysis; (10) Buckling of structures with uncertain imperfections - Personal perspective.

A Mechanics Model for Sensors Imperfectly Bonded to the Skin for Determination of the Young's Moduli of Epidermis and Dermis

PubMed Central

Yuan, J. H.; Shi, Y.; Pharr, M.; Feng, X.; Rogers, John A.; Huang, Yonggang

2016-01-01

A mechanics model is developed for the encapsulated piezoelectric thin-film actuators/sensors system imperfectly bonded to the human skin to simultaneously determine the Young's moduli of the epidermis and dermis as well as the thickness of epidermis. PMID:27330219

The H-theorem and equation of state for kinetic model of imperfect gas

NASA Astrophysics Data System (ADS)

Bishaev, A. M.; Rikov, V. A.; Abgaryan, M. V.

2018-03-01

In the offered article, having used earlier constructed kinetic model for imperfect gas, the equation of state for such gas which takes place which is able in a thermodynamic equilibrium is received and also expression for critical temperature as functions is received from an interaction potential between molecules.

Modeling associations between latent event processes governing time series of pulsing hormones.

PubMed

Liu, Huayu; Carlson, Nichole E; Grunwald, Gary K; Polotsky, Alex J

2017-10-31

This work is motivated by a desire to quantify relationships between two time series of pulsing hormone concentrations. The locations of pulses are not directly observed and may be considered latent event processes. The latent event processes of pulsing hormones are often associated. It is this joint relationship we model. Current approaches to jointly modeling pulsing hormone data generally assume that a pulse in one hormone is coupled with a pulse in another hormone (one-to-one association). However, pulse coupling is often imperfect. Existing joint models are not flexible enough for imperfect systems. In this article, we develop a more flexible class of pulse association models that incorporate parameters quantifying imperfect pulse associations. We propose a novel use of the Cox process model as a model of how pulse events co-occur in time. We embed the Cox process model into a hormone concentration model. Hormone concentration is the observed data. Spatial birth and death Markov chain Monte Carlo is used for estimation. Simulations show the joint model works well for quantifying both perfect and imperfect associations and offers estimation improvements over single hormone analyses. We apply this model to luteinizing hormone (LH) and follicle stimulating hormone (FSH), two reproductive hormones. Use of our joint model results in an ability to investigate novel hypotheses regarding associations between LH and FSH secretion in obese and non-obese women. © 2017, The International Biometric Society.

Economic production quantity model for items with continuous quality characteristic, rework and reject

NASA Astrophysics Data System (ADS)

Tsou, Jia-Chi; Hejazi, Seyed Reza; Rasti Barzoki, Morteza

2012-12-01

The economic production quantity (EPQ) model is a well-known and commonly used inventory control technique. However, the model is built on an unrealistic assumption that all the produced items need to be of perfect quality. Having relaxed this assumption, some researchers have studied the effects of the imperfect products on the inventory control techniques. This article, thus, attempts to develop an EPQ model with continuous quality characteristic and rework. To this end, this study assumes that a produced item follows a general distribution pattern, with its quality being perfect, imperfect or defective. The analysis of the model developed indicates that there is an optimal lot size, which generates minimum total cost. Moreover, the results show that the optimal lot size of the model equals that of the classical EPQ model in case imperfect quality percentage is zero or even close to zero.

Implementation of patient charges at primary care facilities in Kenya: implications of low adherence to user fee policy for users and facility revenue

PubMed Central

Opwora, Antony; Waweru, Evelyn; Toda, Mitsuru; Noor, Abdisalan; Edwards, Tansy; Fegan, Greg; Molyneux, Sassy; Goodman, Catherine

2015-01-01

With user fees now seen as a major hindrance to universal health coverage, many countries have introduced fee reduction or elimination policies, but there is growing evidence that adherence to reduced fees is often highly imperfect. In 2004, Kenya adopted a reduced and uniform user fee policy providing fee exemptions to many groups. We present data on user fee implementation, revenue and expenditure from a nationally representative survey of Kenyan primary health facilities. Data were collected from 248 randomly selected public health centres and dispensaries in 2010, comprising an interview with the health worker in charge, exit interviews with curative outpatients, and a financial record review. Adherence to user fee policy was assessed for eight tracer conditions based on health worker reports, and patients were asked about actual amounts paid. No facilities adhered fully to the user fee policy across all eight tracers, with adherence ranging from 62.2% for an adult with tuberculosis to 4.2% for an adult with malaria. Three quarters of exit interviewees had paid some fees, with a median payment of US dollars (USD) 0.39, and a quarter of interviewees were required to purchase additional medical supplies at a later stage from a private drug retailer. No consistent pattern of association was identified between facility characteristics and policy adherence. User fee revenues accounted for almost all facility cash income, with average revenue of USD 683 per facility per year. Fee revenue was mainly used to cover support staff, non-drug supplies and travel allowances. Adherence to user fee policy was very low, leading to concerns about the impact on access and the financial burden on households. However, the potential to ensure adherence was constrained by the facilities’ need for revenue to cover basic operating costs, highlighting the need for alternative funding strategies for peripheral health facilities. PMID:24837638

Which is more effective for suppressing an infectious disease: imperfect vaccination or defense against contagion?

NASA Astrophysics Data System (ADS)

Kuga, Kazuki; Tanimoto, Jun

2018-02-01

We consider two imperfect ways to protect against an infectious disease such as influenza, namely vaccination giving only partial immunity and a defense against contagion such as wearing a mask. We build up a new analytic framework considering those two cases instead of perfect vaccination, conventionally assumed as a premise, with the assumption of an infinite and well-mixed population. Our framework also considers three different strategy-updating rules based on evolutionary game theory: conventional pairwise comparison with one randomly selected agent, another concept of pairwise comparison referring to a social average, and direct alternative selection not depending on the usual copying concept. We successfully obtain a phase diagram in which vaccination coverage at equilibrium can be compared when assuming the model of either imperfect vaccination or a defense against contagion. The obtained phase diagram reveals that a defense against contagion is marginally inferior to an imperfect vaccination as long as the same coefficient value is used. Highlights - We build a new analytical framework for a vaccination game combined with the susceptible-infected-recovered (SIR) model. - Our model can evaluate imperfect provisions such as vaccination giving only partial immunity and a defense against contagion. - We obtain a phase diagram with which to compare the quantitative effects of partial vaccination and a defense against contagion.

Characterising the effect of global and local geometric imperfections on the numerical performance of a brace member

NASA Astrophysics Data System (ADS)

Hassan, M. S.; Goggins, J.; Salawdeh, S.

2015-07-01

A numerical imperfection study is carried out on a hot rolled tubular brace member under displacement controlled amplitudes. An appropriate range of global and local imperfections is used in the finite element analyses to evaluate the initial-post buckling compressive strength, lateral storey drift, energy dissipation and mid-length lateral deformation of the brace member. The purpose of this study is to assess the impact of the geometrical imperfection on the numerical performance, and to determine an amplitude range that can be used unequivocally for numerical modelling of brace members. It is shown that the amplitude of global imperfections has an effect on the initial response, whereas the amplitude of local imperfections has influence on the resistance capacity of the brace member at higher ductility level. Based on the results, a refined range of amplitude of global and local imperfections is proposed. This range is found to have a good agreement with design standards. In addition, an already established equation to find lateral deformation is compared to results from the analyses and found that the equation with some modification can be used accurately in design. In this paper, a modification factor is proposed in the equation to find the lateral deformation to account for the imperfection amplitude in the numerical analyses of brace members.

Accounting for imperfect detection of groups and individuals when estimating abundance.

PubMed

Clement, Matthew J; Converse, Sarah J; Royle, J Andrew

2017-09-01

If animals are independently detected during surveys, many methods exist for estimating animal abundance despite detection probabilities <1. Common estimators include double-observer models, distance sampling models and combined double-observer and distance sampling models (known as mark-recapture-distance-sampling models; MRDS). When animals reside in groups, however, the assumption of independent detection is violated. In this case, the standard approach is to account for imperfect detection of groups, while assuming that individuals within groups are detected perfectly. However, this assumption is often unsupported. We introduce an abundance estimator for grouped animals when detection of groups is imperfect and group size may be under-counted, but not over-counted. The estimator combines an MRDS model with an N-mixture model to account for imperfect detection of individuals. The new MRDS-Nmix model requires the same data as an MRDS model (independent detection histories, an estimate of distance to transect, and an estimate of group size), plus a second estimate of group size provided by the second observer. We extend the model to situations in which detection of individuals within groups declines with distance. We simulated 12 data sets and used Bayesian methods to compare the performance of the new MRDS-Nmix model to an MRDS model. Abundance estimates generated by the MRDS-Nmix model exhibited minimal bias and nominal coverage levels. In contrast, MRDS abundance estimates were biased low and exhibited poor coverage. Many species of conservation interest reside in groups and could benefit from an estimator that better accounts for imperfect detection. Furthermore, the ability to relax the assumption of perfect detection of individuals within detected groups may allow surveyors to re-allocate resources toward detection of new groups instead of extensive surveys of known groups. We believe the proposed estimator is feasible because the only additional field data required are a second estimate of group size.

Accounting for imperfect detection of groups and individuals when estimating abundance

USGS Publications Warehouse

Clement, Matthew J.; Converse, Sarah J.; Royle, J. Andrew

2017-01-01

If animals are independently detected during surveys, many methods exist for estimating animal abundance despite detection probabilities <1. Common estimators include double-observer models, distance sampling models and combined double-observer and distance sampling models (known as mark-recapture-distance-sampling models; MRDS). When animals reside in groups, however, the assumption of independent detection is violated. In this case, the standard approach is to account for imperfect detection of groups, while assuming that individuals within groups are detected perfectly. However, this assumption is often unsupported. We introduce an abundance estimator for grouped animals when detection of groups is imperfect and group size may be under-counted, but not over-counted. The estimator combines an MRDS model with an N-mixture model to account for imperfect detection of individuals. The new MRDS-Nmix model requires the same data as an MRDS model (independent detection histories, an estimate of distance to transect, and an estimate of group size), plus a second estimate of group size provided by the second observer. We extend the model to situations in which detection of individuals within groups declines with distance. We simulated 12 data sets and used Bayesian methods to compare the performance of the new MRDS-Nmix model to an MRDS model. Abundance estimates generated by the MRDS-Nmix model exhibited minimal bias and nominal coverage levels. In contrast, MRDS abundance estimates were biased low and exhibited poor coverage. Many species of conservation interest reside in groups and could benefit from an estimator that better accounts for imperfect detection. Furthermore, the ability to relax the assumption of perfect detection of individuals within detected groups may allow surveyors to re-allocate resources toward detection of new groups instead of extensive surveys of known groups. We believe the proposed estimator is feasible because the only additional field data required are a second estimate of group size.

Global stability of an age-structure epidemic model with imperfect vaccination and relapse

NASA Astrophysics Data System (ADS)

Cao, Bin; Huo, Hai-Feng; Xiang, Hong

2017-11-01

A new age-structured epidemic model with imperfect vaccination and relapse is proposed. The total population of our model is partitioned into five subclasses: susceptible class S, vaccinated class V, exposed class E, infectious class I and removed class R. Age-structures are equipped with in exposed and recovered classes. Furthermore, imperfect vaccination is also introduced in our model. The basic reproduction number R0 is defined and proved as a threshold parameter of the model. Asymptotic smoothness of solutions and uniform persistence of the system are showed via reformulating the system as a system of Volterra integral equation. Furthermore, by constructing proper Volterra-type Lyapunov functional we get when R0 < 1, the disease-free equilibrium is globally asymptotically stable. When R0 > 1, the endemic equilibrium is globally stable. Our results show that to increase the efficiency of vaccination and reduce influence of relapse are vital essential for controlling epidemic.

Imperfection Sensitivity of Nonlinear Vibration of Curved Single-Walled Carbon Nanotubes Based on Nonlocal Timoshenko Beam Theory

PubMed Central

Eshraghi, Iman; Jalali, Seyed K.; Pugno, Nicola Maria

2016-01-01

Imperfection sensitivity of large amplitude vibration of curved single-walled carbon nanotubes (SWCNTs) is considered in this study. The SWCNT is modeled as a Timoshenko nano-beam and its curved shape is included as an initial geometric imperfection term in the displacement field. Geometric nonlinearities of von Kármán type and nonlocal elasticity theory of Eringen are employed to derive governing equations of motion. Spatial discretization of governing equations and associated boundary conditions is performed using differential quadrature (DQ) method and the corresponding nonlinear eigenvalue problem is iteratively solved. Effects of amplitude and location of the geometric imperfection, and the nonlocal small-scale parameter on the nonlinear frequency for various boundary conditions are investigated. The results show that the geometric imperfection and non-locality play a significant role in the nonlinear vibration characteristics of curved SWCNTs. PMID:28773911

Imperfection Insensitivity Analyses of Advanced Composite Tow-Steered Shells

NASA Technical Reports Server (NTRS)

Wu, K. Chauncey; Farrokh, Babak; Stanford, Bret K.; Weaver, Paul M.

2016-01-01

Two advanced composite tow-steered shells, one with tow overlaps and another without overlaps, were previously designed, fabricated and tested in end compression, both without cutouts, and with small and large cutouts. In each case, good agreement was observed between experimental buckling loads and supporting linear bifurcation buckling analyses. However, previous buckling tests and analyses have shown historically poor correlation, perhaps due to the presence of geometric imperfections that serve as failure initiators. For the tow-steered shells, their circumferential variation in axial stiffness may have suppressed this sensitivity to imperfections, leading to the agreement noted between tests and analyses. To investigate this further, a numerical investigation was performed in this study using geometric imperfections measured from both shells. Finite element models of both shells were analyzed first without, and then, with measured imperfections that were then, superposed in different orientations around the shell longitudinal axis. Small variations in both the axial prebuckling stiffness and global buckling load were observed for the range of imperfections studied here, which suggests that the tow steering, and resulting circumferentially varying axial stiffness, may result in the test-analysis correlation observed for these shells.

Data-assisted reduced-order modeling of extreme events in complex dynamical systems

PubMed Central

Koumoutsakos, Petros

2018-01-01

The prediction of extreme events, from avalanches and droughts to tsunamis and epidemics, depends on the formulation and analysis of relevant, complex dynamical systems. Such dynamical systems are characterized by high intrinsic dimensionality with extreme events having the form of rare transitions that are several standard deviations away from the mean. Such systems are not amenable to classical order-reduction methods through projection of the governing equations due to the large intrinsic dimensionality of the underlying attractor as well as the complexity of the transient events. Alternatively, data-driven techniques aim to quantify the dynamics of specific, critical modes by utilizing data-streams and by expanding the dimensionality of the reduced-order model using delayed coordinates. In turn, these methods have major limitations in regions of the phase space with sparse data, which is the case for extreme events. In this work, we develop a novel hybrid framework that complements an imperfect reduced order model, with data-streams that are integrated though a recurrent neural network (RNN) architecture. The reduced order model has the form of projected equations into a low-dimensional subspace that still contains important dynamical information about the system and it is expanded by a long short-term memory (LSTM) regularization. The LSTM-RNN is trained by analyzing the mismatch between the imperfect model and the data-streams, projected to the reduced-order space. The data-driven model assists the imperfect model in regions where data is available, while for locations where data is sparse the imperfect model still provides a baseline for the prediction of the system state. We assess the developed framework on two challenging prototype systems exhibiting extreme events. We show that the blended approach has improved performance compared with methods that use either data streams or the imperfect model alone. Notably the improvement is more significant in regions associated with extreme events, where data is sparse. PMID:29795631

Data-assisted reduced-order modeling of extreme events in complex dynamical systems.

PubMed

Wan, Zhong Yi; Vlachas, Pantelis; Koumoutsakos, Petros; Sapsis, Themistoklis

2018-01-01

The prediction of extreme events, from avalanches and droughts to tsunamis and epidemics, depends on the formulation and analysis of relevant, complex dynamical systems. Such dynamical systems are characterized by high intrinsic dimensionality with extreme events having the form of rare transitions that are several standard deviations away from the mean. Such systems are not amenable to classical order-reduction methods through projection of the governing equations due to the large intrinsic dimensionality of the underlying attractor as well as the complexity of the transient events. Alternatively, data-driven techniques aim to quantify the dynamics of specific, critical modes by utilizing data-streams and by expanding the dimensionality of the reduced-order model using delayed coordinates. In turn, these methods have major limitations in regions of the phase space with sparse data, which is the case for extreme events. In this work, we develop a novel hybrid framework that complements an imperfect reduced order model, with data-streams that are integrated though a recurrent neural network (RNN) architecture. The reduced order model has the form of projected equations into a low-dimensional subspace that still contains important dynamical information about the system and it is expanded by a long short-term memory (LSTM) regularization. The LSTM-RNN is trained by analyzing the mismatch between the imperfect model and the data-streams, projected to the reduced-order space. The data-driven model assists the imperfect model in regions where data is available, while for locations where data is sparse the imperfect model still provides a baseline for the prediction of the system state. We assess the developed framework on two challenging prototype systems exhibiting extreme events. We show that the blended approach has improved performance compared with methods that use either data streams or the imperfect model alone. Notably the improvement is more significant in regions associated with extreme events, where data is sparse.

Global stability in a tuberculosis model of imperfect treatment with age-dependent latency and relapse.

PubMed

Ren, Shanjing

In this paper, an SEIR epidemic model for an imperfect treatment disease with age-dependent latency and relapse is proposed. The model is well-suited to model tuberculosis. The basic reproduction number R0 is calculated. We obtain the global behavior of the model in terms of R0. If R0< 1, the disease-free equilibrium is globally asymptotically stable, whereas if R0>1, a Lyapunov functional is used to show that the endemic equilibrium is globally stable amongst solutions for which the disease is present.

Professional and Home-Made Face Masks Reduce Exposure to Respiratory Infections among the General Population

PubMed Central

van der Sande, Marianne; Teunis, Peter; Sabel, Rob

2008-01-01

Background Governments are preparing for a potential influenza pandemic. Therefore they need data to assess the possible impact of interventions. Face-masks worn by the general population could be an accessible and affordable intervention, if effective when worn under routine circumstances. Methodology We assessed transmission reduction potential provided by personal respirators, surgical masks and home-made masks when worn during a variety of activities by healthy volunteers and a simulated patient. Principal Findings All types of masks reduced aerosol exposure, relatively stable over time, unaffected by duration of wear or type of activity, but with a high degree of individual variation. Personal respirators were more efficient than surgical masks, which were more efficient than home-made masks. Regardless of mask type, children were less well protected. Outward protection (mask wearing by a mechanical head) was less effective than inward protection (mask wearing by healthy volunteers). Conclusions/Significance Any type of general mask use is likely to decrease viral exposure and infection risk on a population level, in spite of imperfect fit and imperfect adherence, personal respirators providing most protection. Masks worn by patients may not offer as great a degree of protection against aerosol transmission. PMID:18612429

Professional and home-made face masks reduce exposure to respiratory infections among the general population.

PubMed

van der Sande, Marianne; Teunis, Peter; Sabel, Rob

2008-07-09

Governments are preparing for a potential influenza pandemic. Therefore they need data to assess the possible impact of interventions. Face-masks worn by the general population could be an accessible and affordable intervention, if effective when worn under routine circumstances. We assessed transmission reduction potential provided by personal respirators, surgical masks and home-made masks when worn during a variety of activities by healthy volunteers and a simulated patient. All types of masks reduced aerosol exposure, relatively stable over time, unaffected by duration of wear or type of activity, but with a high degree of individual variation. Personal respirators were more efficient than surgical masks, which were more efficient than home-made masks. Regardless of mask type, children were less well protected. Outward protection (mask wearing by a mechanical head) was less effective than inward protection (mask wearing by healthy volunteers). Any type of general mask use is likely to decrease viral exposure and infection risk on a population level, in spite of imperfect fit and imperfect adherence, personal respirators providing most protection. Masks worn by patients may not offer as great a degree of protection against aerosol transmission.

The evolution of imperfect floral mimicry

PubMed Central

Vereecken, Nicolas J.; Schiestl, Florian P.

2008-01-01

The theory of mimicry predicts that selection favors signal refinement in mimics to optimally match the signals released by their specific model species. We provide here chemical and behavioral evidence that a sexually deceptive orchid benefits from its mimetic imperfection to its co-occurring and specific bee model by triggering a stronger response in male bees, which react more intensively to the similar, but novel, scent stimulus provided by the orchid. PMID:18508972

The evolution of imperfect floral mimicry.

PubMed

Vereecken, Nicolas J; Schiestl, Florian P

2008-05-27

The theory of mimicry predicts that selection favors signal refinement in mimics to optimally match the signals released by their specific model species. We provide here chemical and behavioral evidence that a sexually deceptive orchid benefits from its mimetic imperfection to its co-occurring and specific bee model by triggering a stronger response in male bees, which react more intensively to the similar, but novel, scent stimulus provided by the orchid.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hirano, Shin'ichi; Nishi, Sakine; Kobayashi, Tsutomu, E-mail: s.hirano@rikkyo.ac.jp, E-mail: sakine@rikkyo.ac.jp, E-mail: tsutomu@rikkyo.ac.jp

We study the stability of a recently proposed model of scalar-field matter called mimetic dark matter or imperfect dark matter. It has been known that mimetic matter with higher derivative terms suffers from gradient instabilities in scalar perturbations. To seek for an instability-free extension of imperfect dark matter, we develop an effective theory of cosmological perturbations subject to the constraint on the scalar field's kinetic term. This is done by using the unifying framework of general scalar-tensor theories based on the ADM formalism. We demonstrate that it is indeed possible to construct a model of imperfect dark matter which ismore » free from ghost and gradient instabilities. As a side remark, we also show that mimetic F (R) theory is plagued with the Ostrogradsky instability.« less

Determination of Economic Lot Size between Suppliers and Manufacturers for Imperfect Production System with Probabilistic Demand

NASA Astrophysics Data System (ADS)

Yuniar, S.; Wangsaputra, R.; Sinaga, A. T.

2018-03-01

This study aims to develop a combined economical lot size model between supplier and manufacturer for imperfect production processes with probabilistic demand patterns and constant lead times. The supplier side produces the product within a certain time interval then sent to the manufacturer with a certain amount of lot size. Imperfect supplier production systems are characterized by the probability of defective product (γ). The model decision variables are the lot size of the manufacturer's ordering, supplier lot size, and the reorder point of the manufacturer. The optimal decision variables are obtained by minimizing the total expected cost of the combined costs between the suppliers and the manufacturers borne by both parties. The model is built compared to the transactional partnership model, in which the supplier does not participate in the efficiency of its inventory system. A numerical example is given as an illustration of the JELS model and the transactional partnership model. Sensitivity analysis of the model is done by changing the parameters aimed at analyzing the behavior of the developed model.

Analytical simulation of SPS system performance, volume 3, phase 3

NASA Technical Reports Server (NTRS)

Kantak, A. V.; Lindsey, W. C.

1980-01-01

The simulation model for the Solar Power Satellite spaceantenna and the associated system imperfections are described. Overall power transfer efficiency, the key performance issue, is discussed as a function of the system imperfections. Other system performance measures discussed include average power pattern, mean beam gain reduction, and pointing error.

Accounting for hardware imperfections in EIT image reconstruction algorithms.

PubMed

Hartinger, Alzbeta E; Gagnon, Hervé; Guardo, Robert

2007-07-01

Electrical impedance tomography (EIT) is a non-invasive technique for imaging the conductivity distribution of a body section. Different types of EIT images can be reconstructed: absolute, time difference and frequency difference. Reconstruction algorithms are sensitive to many errors which translate into image artefacts. These errors generally result from incorrect modelling or inaccurate measurements. Every reconstruction algorithm incorporates a model of the physical set-up which must be as accurate as possible since any discrepancy with the actual set-up will cause image artefacts. Several methods have been proposed in the literature to improve the model realism, such as creating anatomical-shaped meshes, adding a complete electrode model and tracking changes in electrode contact impedances and positions. Absolute and frequency difference reconstruction algorithms are particularly sensitive to measurement errors and generally assume that measurements are made with an ideal EIT system. Real EIT systems have hardware imperfections that cause measurement errors. These errors translate into image artefacts since the reconstruction algorithm cannot properly discriminate genuine measurement variations produced by the medium under study from those caused by hardware imperfections. We therefore propose a method for eliminating these artefacts by integrating a model of the system hardware imperfections into the reconstruction algorithms. The effectiveness of the method has been evaluated by reconstructing absolute, time difference and frequency difference images with and without the hardware model from data acquired on a resistor mesh phantom. Results have shown that artefacts are smaller for images reconstructed with the model, especially for frequency difference imaging.

Surface instability of an imperfectly bonded thin elastic film under surface van der Waals forces

NASA Astrophysics Data System (ADS)

Wang, Xu; Jing, Rong

2017-02-01

This paper studies surface instability of a thin elastic film imperfectly bonded to a rigid substrate interacting with a rigid contactor through van der Waals forces under plane strain conditions. The film-substrate interface is modeled as a linear spring with vanishing thickness described in terms of the normal and tangential interface parameters. Depending on the ratio of the two imperfect interface parameters, the critical value of the Poisson's ratio for the occurrence of surface wrinkling in the absence of surface energy can be greater than, equal to, or smaller than 0.25, which is the critical Poisson's ratio for a perfect film-substrate interface. The critical surface energy for the inhibition of the surface wrinkling is also obtained. Finally, we propose a very simple and effective method to study the surface instability of a multilayered elastic film with imperfect interfaces interacting with a rigid contactor or with another multilayered elastic film (or a multilayered simply supported plate) with imperfect interfaces.

Efficient calibration for imperfect computer models

DOE PAGES

Tuo, Rui; Wu, C. F. Jeff

2015-12-01

Many computer models contain unknown parameters which need to be estimated using physical observations. Furthermore, the calibration method based on Gaussian process models may lead to unreasonable estimate for imperfect computer models. In this work, we extend their study to calibration problems with stochastic physical data. We propose a novel method, called the L 2 calibration, and show its semiparametric efficiency. The conventional method of the ordinary least squares is also studied. Theoretical analysis shows that it is consistent but not efficient. Here, numerical examples show that the proposed method outperforms the existing ones.

Implementation of patient charges at primary care facilities in Kenya: implications of low adherence to user fee policy for users and facility revenue.

PubMed

Opwora, Antony; Waweru, Evelyn; Toda, Mitsuru; Noor, Abdisalan; Edwards, Tansy; Fegan, Greg; Molyneux, Sassy; Goodman, Catherine

2015-05-01

With user fees now seen as a major hindrance to universal health coverage, many countries have introduced fee reduction or elimination policies, but there is growing evidence that adherence to reduced fees is often highly imperfect. In 2004, Kenya adopted a reduced and uniform user fee policy providing fee exemptions to many groups. We present data on user fee implementation, revenue and expenditure from a nationally representative survey of Kenyan primary health facilities. Data were collected from 248 randomly selected public health centres and dispensaries in 2010, comprising an interview with the health worker in charge, exit interviews with curative outpatients, and a financial record review. Adherence to user fee policy was assessed for eight tracer conditions based on health worker reports, and patients were asked about actual amounts paid. No facilities adhered fully to the user fee policy across all eight tracers, with adherence ranging from 62.2% for an adult with tuberculosis to 4.2% for an adult with malaria. Three quarters of exit interviewees had paid some fees, with a median payment of US dollars (USD) 0.39, and a quarter of interviewees were required to purchase additional medical supplies at a later stage from a private drug retailer. No consistent pattern of association was identified between facility characteristics and policy adherence. User fee revenues accounted for almost all facility cash income, with average revenue of USD 683 per facility per year. Fee revenue was mainly used to cover support staff, non-drug supplies and travel allowances. Adherence to user fee policy was very low, leading to concerns about the impact on access and the financial burden on households. However, the potential to ensure adherence was constrained by the facilities' need for revenue to cover basic operating costs, highlighting the need for alternative funding strategies for peripheral health facilities. Published by Oxford University Press in association with The London School of Hygiene and Tropical Medicine © The Author 2014.

A reliable facility location design model with site-dependent disruption in the imperfect information context

PubMed Central

Yun, Lifen; Wang, Xifu; Fan, Hongqiang; Li, Xiaopeng

2017-01-01

This paper proposes a reliable facility location design model under imperfect information with site-dependent disruptions; i.e., each facility is subject to a unique disruption probability that varies across the space. In the imperfect information contexts, customers adopt a realistic “trial-and-error” strategy to visit facilities; i.e., they visit a number of pre-assigned facilities sequentially until they arrive at the first operational facility or give up looking for the service. This proposed model aims to balance initial facility investment and expected long-term operational cost by finding the optimal facility locations. A nonlinear integer programming model is proposed to describe this problem. We apply a linearization technique to reduce the difficulty of solving the proposed model. A number of problem instances are studied to illustrate the performance of the proposed model. The results indicate that our proposed model can reveal a number of interesting insights into the facility location design with site-dependent disruptions, including the benefit of backup facilities and system robustness against variation of the loss-of-service penalty. PMID:28486564

Strategies for Reduced-Order Models in Uncertainty Quantification of Complex Turbulent Dynamical Systems

NASA Astrophysics Data System (ADS)

Qi, Di

Turbulent dynamical systems are ubiquitous in science and engineering. Uncertainty quantification (UQ) in turbulent dynamical systems is a grand challenge where the goal is to obtain statistical estimates for key physical quantities. In the development of a proper UQ scheme for systems characterized by both a high-dimensional phase space and a large number of instabilities, significant model errors compared with the true natural signal are always unavoidable due to both the imperfect understanding of the underlying physical processes and the limited computational resources available. One central issue in contemporary research is the development of a systematic methodology for reduced order models that can recover the crucial features both with model fidelity in statistical equilibrium and with model sensitivity in response to perturbations. In the first part, we discuss a general mathematical framework to construct statistically accurate reduced-order models that have skill in capturing the statistical variability in the principal directions of a general class of complex systems with quadratic nonlinearity. A systematic hierarchy of simple statistical closure schemes, which are built through new global statistical energy conservation principles combined with statistical equilibrium fidelity, are designed and tested for UQ of these problems. Second, the capacity of imperfect low-order stochastic approximations to model extreme events in a passive scalar field advected by turbulent flows is investigated. The effects in complicated flow systems are considered including strong nonlinear and non-Gaussian interactions, and much simpler and cheaper imperfect models with model error are constructed to capture the crucial statistical features in the stationary tracer field. Several mathematical ideas are introduced to improve the prediction skill of the imperfect reduced-order models. Most importantly, empirical information theory and statistical linear response theory are applied in the training phase for calibrating model errors to achieve optimal imperfect model parameters; and total statistical energy dynamics are introduced to improve the model sensitivity in the prediction phase especially when strong external perturbations are exerted. The validity of reduced-order models for predicting statistical responses and intermittency is demonstrated on a series of instructive models with increasing complexity, including the stochastic triad model, the Lorenz '96 model, and models for barotropic and baroclinic turbulence. The skillful low-order modeling methods developed here should also be useful for other applications such as efficient algorithms for data assimilation.

Predicting species distributions from checklist data using site-occupancy models

USGS Publications Warehouse

Kery, M.; Gardner, B.; Monnerat, C.

2010-01-01

Aim: (1) To increase awareness of the challenges induced by imperfect detection, which is a fundamental issue in species distribution modelling; (2) to emphasize the value of replicate observations for species distribution modelling; and (3) to show how 'cheap' checklist data in faunal/floral databases may be used for the rigorous modelling of distributions by site-occupancy models. Location: Switzerland. Methods: We used checklist data collected by volunteers during 1999 and 2000 to analyse the distribution of the blue hawker, Aeshna cyanea (Odonata, Aeshnidae), a common dragonfly in Switzerland. We used data from repeated visits to 1-ha pixels to derive 'detection histories' and apply site-occupancy models to estimate the 'true' species distribution, i.e. corrected for imperfect detection. We modelled blue hawker distribution as a function of elevation and year and its detection probability of elevation, year and season. Results: The best model contained cubic polynomial elevation effects for distribution and quadratic effects of elevation and season for detectability. We compared the site-occupancy model with a conventional distribution model based on a generalized linear model, which assumes perfect detectability (p = 1). The conventional distribution map looked very different from the distribution map obtained using site-occupancy models that accounted for the imperfect detection. The conventional model underestimated the species distribution by 60%, and the slope parameters of the occurrence-elevation relationship were also underestimated when assuming p = 1. Elevation was not only an important predictor of blue hawker occurrence, but also of the detection probability, with a bell-shaped relationship. Furthermore, detectability increased over the season. The average detection probability was estimated at only 0.19 per survey. Main conclusions: Conventional species distribution models do not model species distributions per se but rather the apparent distribution, i.e. an unknown proportion of species distributions. That unknown proportion is equivalent to detectability. Imperfect detection in conventional species distribution models yields underestimates of the extent of distributions and covariate effects that are biased towards zero. In addition, patterns in detectability will erroneously be ascribed to species distributions. In contrast, site-occupancy models applied to replicated detection/non-detection data offer a powerful framework for making inferences about species distributions corrected for imperfect detection. The use of 'cheap' checklist data greatly enhances the scope of applications of this useful class of models. ?? 2010 Blackwell Publishing Ltd.

Accounting for imperfect detection is critical for inferring marine turtle nesting population trends.

PubMed

Pfaller, Joseph B; Bjorndal, Karen A; Chaloupka, Milani; Williams, Kristina L; Frick, Michael G; Bolten, Alan B

2013-01-01

Assessments of population trends based on time-series counts of individuals are complicated by imperfect detection, which can lead to serious misinterpretations of data. Population trends of threatened marine turtles worldwide are usually based on counts of nests or nesting females. We analyze 39 years of nest-count, female-count, and capture-mark-recapture (CMR) data for nesting loggerhead turtles (Caretta caretta) on Wassaw Island, Georgia, USA. Annual counts of nests and females, not corrected for imperfect detection, yield significant, positive trends in abundance. However, multistate open robust design modeling of CMR data that accounts for changes in imperfect detection reveals that the annual abundance of nesting females has remained essentially constant over the 39-year period. The dichotomy could result from improvements in surveys or increased within-season nest-site fidelity in females, either of which would increase detection probability. For the first time in a marine turtle population, we compare results of population trend analyses that do and do not account for imperfect detection and demonstrate the potential for erroneous conclusions. Past assessments of marine turtle population trends based exclusively on count data should be interpreted with caution and re-evaluated when possible. These concerns apply equally to population assessments of all species with imperfect detection.

Bias in logistic regression due to imperfect diagnostic test results and practical correction approaches.

PubMed

Valle, Denis; Lima, Joanna M Tucker; Millar, Justin; Amratia, Punam; Haque, Ubydul

2015-11-04

Logistic regression is a statistical model widely used in cross-sectional and cohort studies to identify and quantify the effects of potential disease risk factors. However, the impact of imperfect tests on adjusted odds ratios (and thus on the identification of risk factors) is under-appreciated. The purpose of this article is to draw attention to the problem associated with modelling imperfect diagnostic tests, and propose simple Bayesian models to adequately address this issue. A systematic literature review was conducted to determine the proportion of malaria studies that appropriately accounted for false-negatives/false-positives in a logistic regression setting. Inference from the standard logistic regression was also compared with that from three proposed Bayesian models using simulations and malaria data from the western Brazilian Amazon. A systematic literature review suggests that malaria epidemiologists are largely unaware of the problem of using logistic regression to model imperfect diagnostic test results. Simulation results reveal that statistical inference can be substantially improved when using the proposed Bayesian models versus the standard logistic regression. Finally, analysis of original malaria data with one of the proposed Bayesian models reveals that microscopy sensitivity is strongly influenced by how long people have lived in the study region, and an important risk factor (i.e., participation in forest extractivism) is identified that would have been missed by standard logistic regression. Given the numerous diagnostic methods employed by malaria researchers and the ubiquitous use of logistic regression to model the results of these diagnostic tests, this paper provides critical guidelines to improve data analysis practice in the presence of misclassification error. Easy-to-use code that can be readily adapted to WinBUGS is provided, enabling straightforward implementation of the proposed Bayesian models.

Maximum likelihood estimation of label imperfections and its use in the identification of mislabeled patterns

NASA Technical Reports Server (NTRS)

Chittineni, C. B.

1979-01-01

The problem of estimating label imperfections and the use of the estimation in identifying mislabeled patterns is presented. Expressions for the maximum likelihood estimates of classification errors and a priori probabilities are derived from the classification of a set of labeled patterns. Expressions also are given for the asymptotic variances of probability of correct classification and proportions. Simple models are developed for imperfections in the labels and for classification errors and are used in the formulation of a maximum likelihood estimation scheme. Schemes are presented for the identification of mislabeled patterns in terms of threshold on the discriminant functions for both two-class and multiclass cases. Expressions are derived for the probability that the imperfect label identification scheme will result in a wrong decision and are used in computing thresholds. The results of practical applications of these techniques in the processing of remotely sensed multispectral data are presented.

Occupancy Estimation and Modeling : Inferring Patterns and Dynamics of Species Occurrence

USGS Publications Warehouse

MacKenzie, D.I.; Nichols, J.D.; Royle, J. Andrew; Pollock, K.H.; Bailey, L.L.; Hines, J.E.

2006-01-01

This is the first book to examine the latest methods in analyzing presence/absence data surveys. Using four classes of models (single-species, single-season; single-species, multiple season; multiple-species, single-season; and multiple-species, multiple-season), the authors discuss the practical sampling situation, present a likelihood-based model enabling direct estimation of the occupancy-related parameters while allowing for imperfect detectability, and make recommendations for designing studies using these models. It provides authoritative insights into the latest in estimation modeling; discusses multiple models which lay the groundwork for future study designs; addresses critical issues of imperfect detectibility and its effects on estimation; and explores the role of probability in estimating in detail.

Reduction of shock induced noise in imperfectly expanded supersonic jets using convex optimization

NASA Astrophysics Data System (ADS)

Adhikari, Sam

2007-11-01

Imperfectly expanded jets generate screech noise. The imbalance between the backpressure and the exit pressure of the imperfectly expanded jets produce shock cells and expansion or compression waves from the nozzle. The instability waves and the shock cells interact to generate the screech sound. The mathematical model consists of cylindrical coordinate based full Navier-Stokes equations and large-eddy-simulation turbulence modeling. Analytical and computational analysis of the three-dimensional helical effects provide a model that relates several parameters with shock cell patterns, screech frequency and distribution of shock generation locations. Convex optimization techniques minimize the shock cell patterns and the instability waves. The objective functions are (convex) quadratic and the constraint functions are affine. In the quadratic optimization programs, minimization of the quadratic functions over a set of polyhedrons provides the optimal result. Various industry standard methods like regression analysis, distance between polyhedra, bounding variance, Markowitz optimization, and second order cone programming is used for Quadratic Optimization.

Influence of yield surface curvature on the macroscopic yielding and ductile failure of isotropic porous plastic materials

NASA Astrophysics Data System (ADS)

Dæhli, Lars Edvard Bryhni; Morin, David; Børvik, Tore; Hopperstad, Odd Sture

2017-10-01

Numerical unit cell models of an approximative representative volume element for a porous ductile solid are utilized to investigate differences in the mechanical response between a quadratic and a non-quadratic matrix yield surface. A Hershey equivalent stress measure with two distinct values of the yield surface exponent is employed as the matrix description. Results from the unit cell calculations are further used to calibrate a heuristic extension of the Gurson model which incorporates effects of the third deviatoric stress invariant. An assessment of the porous plasticity model reveals its ability to describe the unit cell response to some extent, however underestimating the effect of the Lode parameter for the lower triaxiality ratios imposed in this study when compared to unit cell simulations. Ductile failure predictions by means of finite element simulations using a unit cell model that resembles an imperfection band are then conducted to examine how the non-quadratic matrix yield surface influences the failure strain as compared to the quadratic matrix yield surface. Further, strain localization predictions based on bifurcation analyses and imperfection band analyses are undertaken using the calibrated porous plasticity model. These simulations are then compared to the unit cell calculations in order to elucidate the differences between the various modelling strategies. The current study reveals that strain localization analyses using an imperfection band model and a spatially discretized unit cell are in reasonable agreement, while the bifurcation analyses predict higher strain levels at localization. Imperfection band analyses are finally used to calculate failure loci for the quadratic and the non-quadratic matrix yield surface under a wide range of loading conditions. The underlying matrix yield surface is demonstrated to have a pronounced influence on the onset of strain localization.

Occupancy models for monitoring marine fish: a bayesian hierarchical approach to model imperfect detection with a novel gear combination.

PubMed

Coggins, Lewis G; Bacheler, Nathan M; Gwinn, Daniel C

2014-01-01

Occupancy models using incidence data collected repeatedly at sites across the range of a population are increasingly employed to infer patterns and processes influencing population distribution and dynamics. While such work is common in terrestrial systems, fewer examples exist in marine applications. This disparity likely exists because the replicate samples required by these models to account for imperfect detection are often impractical to obtain when surveying aquatic organisms, particularly fishes. We employ simultaneous sampling using fish traps and novel underwater camera observations to generate the requisite replicate samples for occupancy models of red snapper, a reef fish species. Since the replicate samples are collected simultaneously by multiple sampling devices, many typical problems encountered when obtaining replicate observations are avoided. Our results suggest that augmenting traditional fish trap sampling with camera observations not only doubled the probability of detecting red snapper in reef habitats off the Southeast coast of the United States, but supplied the necessary observations to infer factors influencing population distribution and abundance while accounting for imperfect detection. We found that detection probabilities tended to be higher for camera traps than traditional fish traps. Furthermore, camera trap detections were influenced by the current direction and turbidity of the water, indicating that collecting data on these variables is important for future monitoring. These models indicate that the distribution and abundance of this species is more heavily influenced by latitude and depth than by micro-scale reef characteristics lending credence to previous characterizations of red snapper as a reef habitat generalist. This study demonstrates the utility of simultaneous sampling devices, including camera traps, in aquatic environments to inform occupancy models and account for imperfect detection when describing factors influencing fish population distribution and dynamics.

Occupancy Models for Monitoring Marine Fish: A Bayesian Hierarchical Approach to Model Imperfect Detection with a Novel Gear Combination

PubMed Central

Coggins, Lewis G.; Bacheler, Nathan M.; Gwinn, Daniel C.

2014-01-01

Occupancy models using incidence data collected repeatedly at sites across the range of a population are increasingly employed to infer patterns and processes influencing population distribution and dynamics. While such work is common in terrestrial systems, fewer examples exist in marine applications. This disparity likely exists because the replicate samples required by these models to account for imperfect detection are often impractical to obtain when surveying aquatic organisms, particularly fishes. We employ simultaneous sampling using fish traps and novel underwater camera observations to generate the requisite replicate samples for occupancy models of red snapper, a reef fish species. Since the replicate samples are collected simultaneously by multiple sampling devices, many typical problems encountered when obtaining replicate observations are avoided. Our results suggest that augmenting traditional fish trap sampling with camera observations not only doubled the probability of detecting red snapper in reef habitats off the Southeast coast of the United States, but supplied the necessary observations to infer factors influencing population distribution and abundance while accounting for imperfect detection. We found that detection probabilities tended to be higher for camera traps than traditional fish traps. Furthermore, camera trap detections were influenced by the current direction and turbidity of the water, indicating that collecting data on these variables is important for future monitoring. These models indicate that the distribution and abundance of this species is more heavily influenced by latitude and depth than by micro-scale reef characteristics lending credence to previous characterizations of red snapper as a reef habitat generalist. This study demonstrates the utility of simultaneous sampling devices, including camera traps, in aquatic environments to inform occupancy models and account for imperfect detection when describing factors influencing fish population distribution and dynamics. PMID:25255325

Generalized random sign and alert delay models for imperfect maintenance.

PubMed

Dijoux, Yann; Gaudoin, Olivier

2014-04-01

This paper considers the modelling of the process of Corrective and condition-based Preventive Maintenance, for complex repairable systems. In order to take into account the dependency between both types of maintenance and the possibility of imperfect maintenance, Generalized Competing Risks models have been introduced in "Doyen and Gaudoin (J Appl Probab 43:825-839, 2006)". In this paper, we study two classes of these models, the Generalized Random Sign and Generalized Alert Delay models. A Generalized Competing Risks model can be built as a generalization of a particular Usual Competing Risks model, either by using a virtual age framework or not. The models properties are studied and their parameterizations are discussed. Finally, simulation results and an application to real data are presented.

Probability-based methodology for buckling investigation of sandwich composite shells with and without cut-outs

NASA Astrophysics Data System (ADS)

Alfano, M.; Bisagni, C.

2017-01-01

The objective of the running EU project DESICOS (New Robust DESign Guideline for Imperfection Sensitive COmposite Launcher Structures) is to formulate an improved shell design methodology in order to meet the demand of aerospace industry for lighter structures. Within the project, this article discusses the development of a probability-based methodology developed at Politecnico di Milano. It is based on the combination of the Stress-Strength Interference Method and the Latin Hypercube Method with the aim to predict the bucking response of three sandwich composite cylindrical shells, assuming a loading condition of pure compression. The three shells are made of the same material, but have different stacking sequence and geometric dimensions. One of them presents three circular cut-outs. Different types of input imperfections, treated as random variables, are taken into account independently and in combination: variability in longitudinal Young's modulus, ply misalignment, geometric imperfections, and boundary imperfections. The methodology enables a first assessment of the structural reliability of the shells through the calculation of a probabilistic buckling factor for a specified level of probability. The factor depends highly on the reliability level, on the number of adopted samples, and on the assumptions made in modeling the input imperfections. The main advantage of the developed procedure is the versatility, as it can be applied to the buckling analysis of laminated composite shells and sandwich composite shells including different types of imperfections.

The importance of accounting for imperfect detection when estimating functional and phylogenetic community structure.

PubMed

Si, Xingfeng; Cadotte, Marc W; Zhao, Yuhao; Zhou, Haonan; Zeng, Di; Li, Jiaqi; Jin, Tinghao; Ren, Peng; Wang, Yanping; Ding, Ping; Tingley, Morgan W

2018-06-26

Incorporating imperfect detection when estimating species richness has become commonplace in the past decade. However, the question of how imperfect detection of species affects estimates of functional and phylogenetic community structure remains untested. We used long-term counts of breeding bird species that were detected at least once on islands in a land-bridge island system, and employed multi-species occupancy models to assess the effects of imperfect detection of species on estimates of bird diversity and community structure by incorporating species traits and phylogenies. Our results showed that taxonomic, functional, and phylogenetic diversity were all underestimated significantly as a result of species' imperfect detection, with taxonomic diversity showing the greatest bias. The functional and phylogenetic structure calculated from observed communities were both more clustered than those from the detection-corrected communities due to missed distinct species. The discrepancy between observed and estimated diversity differed according to the measure of biodiversity employed. Our study demonstrates the importance of accounting for species' imperfect detection in biodiversity studies, especially for functional and phylogenetic community ecology, and when attempting to infer community assembly processes. With datasets that allow for detection-corrected community structure, we can better estimate diversity and infer the underlying mechanisms that structure community assembly, and thus make reliable management decisions for the conservation of biodiversity. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Martian airfall dust on smooth, inclined surfaces as observed on the Phoenix Mars Lander telltale mirror

NASA Astrophysics Data System (ADS)

Moores, John E.; Ha, Taesung; Lemmon, Mark T.; Gunnlaugsson, Haraldur Páll

2015-10-01

The telltale mirror, a smooth inclined surface raised over 1 m above the deck of the Phoenix Mars Lander, was observed by the Surface Stereo Imager (SSI) several times per sol during the Phoenix Mars Lander mission. These observations were combined with a radiative transfer model to determine the thickness of dust on the wind telltale mirror as a function of time. 239 telltale sequences were analyzed and dustiness was determined on a diurnal and seasonal basis. The thickness of accumulated dust did not follow any particular diurnal or seasonal trend. The dust thickness on the mirror over the mission was 0.82±0.39 μm, which suggests a similar thickness to the modal scattering particle diameter. This suggests that inclining a surface beyond the angle of repose and polishing it to remove surface imperfections is an effective way to mitigate the accumulation of dust to less than a micron over a wide range of meteorological conditions and could be beneficial for surfaces which can tolerate some dust but not thick accumulations, such as solar panels. However, such a surface will not remain completely dust free through this action alone and mechanical or electrical clearing must be employed to remove adhered dust if a pristine surface is required. The single-scattering phase function of the dust on the mirror was consistent with the single-scattering phase function of martian aerosol dust at 450 nm, suggesting that this result is inconsistent with models of the atmosphere which require vertically or horizontally separated components or broad size distributions to explain the scattering behavior of these aerosols in the blue. The single-scattering behavior of the dust on the mirror is also consistent with Hapke modeling of spherical particles. The presence of a monolayer of particles would tend to support the spherical conclusion: such particles would be most strongly adhered electrostatically.

Analysis of imperfections in the coherent optical excitation of single atoms to Rydberg states

NASA Astrophysics Data System (ADS)

de Léséleuc, Sylvain; Barredo, Daniel; Lienhard, Vincent; Browaeys, Antoine; Lahaye, Thierry

2018-05-01

We study experimentally various physical limitations and technical imperfections that lead to damping and finite contrast of optically driven Rabi oscillations between ground and Rydberg states of a single atom. Finite contrast is due to preparation and detection errors, and we show how to model and measure them accurately. Part of these errors originates from the finite lifetime of Rydberg states, and we observe its n3 scaling with the principal quantum number n . To explain the damping of Rabi oscillations, we use simple numerical models taking into account independently measured experimental imperfections and show that the observed damping actually results from the accumulation of several small effects, each at the level of a few percent. We discuss prospects for improving the coherence of ground-Rydberg Rabi oscillations in view of applications in quantum simulation and quantum information processing with arrays of single Rydberg atoms.

Modeling Being "Lost": Imperfect Situation Awareness

NASA Technical Reports Server (NTRS)

Middleton, Victor E.

2011-01-01

Being "lost" is an exemplar of imperfect Situation Awareness/Situation Understanding (SA/SU) -- information/knowledge that is uncertain, incomplete, and/or just wrong. Being "lost" may be a geo-spatial condition - not knowing/being wrong about where to go or how to get there. More broadly, being "lost" can serve as a metaphor for uncertainty and/or inaccuracy - not knowing/being wrong about how one fits into a larger world view, what one wants to do, or how to do it. This paper discusses using agent based modeling (ABM) to explore imperfect SA/SU, simulating geo-spatially "lost" intelligent agents trying to navigate in a virtual world. Each agent has a unique "mental map" -- its idiosyncratic view of its geo-spatial environment. Its decisions are based on this idiosyncratic view, but behavior outcomes are based on ground truth. Consequently, the rate and degree to which an agent's expectations diverge from ground truth provide measures of that agent's SA/SU.

Imperfection and radiation damage in protein crystals studied with coherent radiation

PubMed Central

Nave, Colin; Sutton, Geoff; Evans, Gwyndaf; Owen, Robin; Rau, Christoph; Robinson, Ian; Stuart, David Ian

2016-01-01

Fringes and speckles occur within diffraction spots when a crystal is illuminated with coherent radiation during X-ray diffraction. The additional information in these features provides insight into the imperfections in the crystal at the sub-micrometre scale. In addition, these features can provide more accurate intensity measurements (e.g. by model-based profile fitting), detwinning (by distinguishing the various components), phasing (by exploiting sampling of the molecular transform) and refinement (by distinguishing regions with different unit-cell parameters). In order to exploit these potential benefits, the features due to coherent diffraction have to be recorded and any change due to radiation damage properly modelled. Initial results from recording coherent diffraction at cryotemperatures from polyhedrin crystals of approximately 2 µm in size are described. These measurements allowed information about the type of crystal imperfections to be obtained at the sub-micrometre level, together with the changes due to radiation damage. PMID:26698068

Trend estimation in populations with imperfect detection

USGS Publications Warehouse

Kery, Marc; Dorazio, Robert M.; Soldaat, Leo; Van Strien, Arco; Zuiderwijk, Annie; Royle, J. Andrew

2009-01-01

1. Trends of animal populations are of great interest in ecology but cannot be directly observed owing to imperfect detection. Binomial mixture models use replicated counts to estimate abundance, corrected for detection, in demographically closed populations. Here, we extend these models to open populations and illustrate them using sand lizard Lacerta agilis counts from the national Dutch reptile monitoring scheme. 2. Our model requires replicated counts from multiple sites in each of several periods, within which population closure is assumed. Counts are described by a hierarchical generalized linear model, where the state model deals with spatio-temporal patterns in true abundance and the observation model with imperfect counts, given that true state. We used WinBUGS to fit the model to lizard counts from 208 transects with 1–10 (mean 3) replicate surveys during each spring 1994–2005. 3. Our state model for abundance contained two independent log-linear Poisson regressions on year for coastal and inland sites, and random site effects to account for unexplained heterogeneity. The observation model for detection of an individual lizard contained effects of region, survey date, temperature, observer experience and random survey effects. 4. Lizard populations increased in both regions but more steeply on the coast. Detectability increased over the first few years of the study, was greater on the coast and for the most experienced observers, and highest around 1 June. Interestingly, the population increase inland was not detectable when the observed counts were analysed without account of detectability. The proportional increase between 1994 and 2005 in total lizard abundance across all sites was estimated at 86% (95% CRI 35–151). 5. Synthesis and applications. Open-population binomial mixture models are attractive for studying true population dynamics while explicitly accounting for the observation process, i.e. imperfect detection. We emphasize the important conceptual benefit provided by temporal replicate observations in terms of the interpretability of animal counts.

Effect of Geometrical Imperfection on Buckling Failure of ITER VVPSS Tank

NASA Astrophysics Data System (ADS)

Jha, Saroj Kumar; Gupta, Girish Kumar; Pandey, Manish Kumar; Bhattacharya, Avik; Jogi, Gaurav; Bhardwaj, Anil Kumar

2017-04-01

The ‘Vacuum Vessel Pressure Suppression System’ (VVPSS) is part of ITER machine, which is designed to protect the ITER Vacuum Vessel and its connected systems, from an over-pressure situation. It is comprised of a partially evacuated tank of stainless steel approximately 46 m long and 6 m in diameter and thickness 30 mm. It is to hold approximately 675 tonnes of water at room temperature to condense the steam resulting from the adverse water leakage into the Vacuum Vessel chamber. For any vacuum vessel, geometrical imperfection has significant effect on buckling failure and structural integrity. Major geometrical imperfection in VVPSS tank depends on form tolerances. To study the effect of geometrical imperfection on buckling failure of VVPSS tank, finite element analysis (FEA) has been performed in line with ASME section VIII division 2 part 5 [1], ‘design by analysis method’. Linear buckling analysis has been performed to get the buckled shape and displacement. Geometrical imperfection due to form tolerance is incorporated in FEA model of VVPSS tank by scaling the resulted buckled shape by a factor ‘60’. This buckled shape model is used as input geometry for plastic collapse and buckling failure assessment. Plastic collapse and buckling failure of VVPSS tank has been assessed by using the elastic-plastic analysis method. This analysis has been performed for different values of form tolerance. The results of analysis show that displacement and load proportionality factor (LPF) vary inversely with form tolerance. For higher values of form tolerance LPF reduces significantly with high values of displacement.

Influence of stochastic geometric imperfections on the load-carrying behaviour of thin-walled structures using constrained random fields

NASA Astrophysics Data System (ADS)

Lauterbach, S.; Fina, M.; Wagner, W.

2018-04-01

Since structural engineering requires highly developed and optimized structures, the thickness dependency is one of the most controversially debated topics. This paper deals with stability analysis of lightweight thin structures combined with arbitrary geometrical imperfections. Generally known design guidelines only consider imperfections for simple shapes and loading, whereas for complex structures the lower-bound design philosophy still holds. Herein, uncertainties are considered with an empirical knockdown factor representing a lower bound of existing measurements. To fully understand and predict expected bearable loads, numerical investigations are essential, including geometrical imperfections. These are implemented into a stand-alone program code with a stochastic approach to compute random fields as geometric imperfections that are applied to nodes of the finite element mesh of selected structural examples. The stochastic approach uses the Karhunen-Loève expansion for the random field discretization. For this approach, the so-called correlation length l_c controls the random field in a powerful way. This parameter has a major influence on the buckling shape, and also on the stability load. First, the impact of the correlation length is studied for simple structures. Second, since most structures for engineering devices are more complex and combined structures, these are intensively discussed with the focus on constrained random fields for e.g. flange-web-intersections. Specific constraints for those random fields are pointed out with regard to the finite element model. Further, geometrical imperfections vanish where the structure is supported.

A collaborative vendor-buyer production-inventory systems with imperfect quality items, inspection errors, and stochastic demand under budget capacity constraint: a Karush-Kuhn-Tucker conditions approach

NASA Astrophysics Data System (ADS)

Kurdhi, N. A.; Nurhayati, R. A.; Wiyono, S. B.; Handajani, S. S.; Martini, T. S.

2017-01-01

In this paper, we develop an integrated inventory model considering the imperfect quality items, inspection error, controllable lead time, and budget capacity constraint. The imperfect items were uniformly distributed and detected on the screening process. However there are two types of possibilities. The first is type I of inspection error (when a non-defective item classified as defective) and the second is type II of inspection error (when a defective item classified as non-defective). The demand during the lead time is unknown, and it follows the normal distribution. The lead time can be controlled by adding the crashing cost. Furthermore, the existence of the budget capacity constraint is caused by the limited purchasing cost. The purposes of this research are: to modify the integrated vendor and buyer inventory model, to establish the optimal solution using Kuhn-Tucker’s conditions, and to apply the models. Based on the result of application and the sensitivity analysis, it can be obtained minimum integrated inventory total cost rather than separated inventory.

Effects of Shell-Buckling Knockdown Factors in Large Cylindrical Shells

NASA Technical Reports Server (NTRS)

Hrinda, Glenn A.

2012-01-01

Shell-buckling knockdown factors (SBKF) have been used in large cylindrical shell structures to account for uncertainty in buckling loads. As the diameter of the cylinder increases, achieving the manufacturing tolerances becomes increasingly more difficult. Knockdown factors account for manufacturing imperfections in the shell geometry by decreasing the allowable buckling load of the cylinder. In this paper, large-diameter (33 ft) cylinders are investigated by using various SBKF's. An investigation that is based on finite-element analysis (FEA) is used to develop design sensitivity relationships. Different manufacturing imperfections are modeled into a perfect cylinder to investigate the effects of these imperfections on buckling. The analysis results may be applicable to large- diameter rockets, cylindrical tower structures, bulk storage tanks, and silos.

Mental models of adherence: parallels in perceptions, values, and expectations in adherence to prescribed home exercise programs and other personal regimens.

PubMed

Rizzo, Jon; Bell, Alexandra

2018-05-09

A mental model is the collection of an individual's perceptions, values, and expectations about a particular aspect of their life, which strongly influences behaviors. This study explored orthopedic outpatients mental models of adherence to prescribed home exercise programs and how they related to mental models of adherence to other types of personal regimens. The study followed an interpretive description qualitative design. Data were collected via two semi-structured interviews. Interview One focused on participants prior experiences adhering to personal regimens. Interview Two focused on experiences adhering to their current prescribed home exercise program. Data analysis followed a constant comparative method. Findings revealed similarity in perceptions, values, and expectations that informed individuals mental models of adherence to personal regimens and prescribed home exercise programs. Perceived realized results, expected results, perceived social supports, and value of convenience characterized mental models of adherence. Parallels between mental models of adherence for prescribed home exercise and other personal regimens suggest that patients adherence behavior to prescribed routines may be influenced by adherence experiences in other aspects of their lives. By gaining insight into patients adherence experiences, values, and expectations across life domains, clinicians may tailor supports that enhance home exercise adherence. Implications for Rehabilitation A mental model is the collection of an individual's perceptions, values, and expectations about a particular aspect of their life, which is based on prior experiences and strongly influences behaviors. This study demonstrated similarity in orthopedic outpatients mental models of adherence to prescribed home exercise programs and adherence to personal regimens in other aspects of their lives. Physical therapists should inquire about patients non-medical adherence experiences, as strategies patients customarily use to adhere to other activities may inform strategies to promote prescribed home exercise adherence.

The Effects of Geometric and Loading Imperfections on the Response and Lower-Bound Buckling Load of a Compression-Loaded Cylindrical Shell

NASA Technical Reports Server (NTRS)

Kriegesmann, Benedikt; Hilburger, Mark W.; Rolfes, Raimund

2012-01-01

Results from a numerical study of the buckling response of a thin-walled compressionloaded isotropic circular cylindrical shell with initial geometric and loading imperfections are used to determine a lower bound buckling load estimate suitable for preliminary design. The lower bound prediction techniques presented herein include an imperfection caused by a lateral perturbation load, an imperfection in the shape of a single stress-free dimple (similar to the lateral pertubation imperfection), and a distributed load imperfection that induces a nonuniform load in the shell. The ABAQUS finite element code is used for the analyses. Responses of the cylinders for selected imperfection amplitudes and imperfection types are considered, and the effect of each imperfection is compared to the response of a geometrically perfect cylinder. The results indicate that compression-loaded shells subjected to a lateral perturbation load or a single dimple imperfection, and a nonuniform load imperfection, exhibit similar buckling behavior and lower bound trends and the predicted lower bounds are much less conservative than the corresponding design recommendation NASA SP-8007 for the design of buckling-critical shells. In addition, the lateral perturbation technique and the distributed load imperfection produce response characteristics that are physically meaningful and can be validated via laboratory testing.

Nonlinear layered lattice model and generalized solitary waves in imperfectly bonded structures.

PubMed

Khusnutdinova, Karima R; Samsonov, Alexander M; Zakharov, Alexey S

2009-05-01

We study nonlinear waves in a two-layered imperfectly bonded structure using a nonlinear lattice model. The key element of the model is an anharmonic chain of oscillating dipoles, which can be viewed as a basic lattice analog of a one-dimensional macroscopic waveguide. Long nonlinear longitudinal waves in a layered lattice with a soft middle (or bonding) layer are governed by a system of coupled Boussinesq-type equations. For this system we find conservation laws and show that pure solitary waves, which exist in a single equation and can exist in the coupled system in the symmetric case, are structurally unstable and are replaced with generalized solitary waves.

An information-motivation-behavioral skills model of adherence to antiretroviral therapy.

PubMed

Fisher, Jeffrey D; Fisher, William A; Amico, K Rivet; Harman, Jennifer J

2006-07-01

HIV-positive persons who do not maintain consistently high levels of adherence to often complex and toxic highly active antiretroviral therapy (HAART) regimens may experience therapeutic failure and deterioration of health status and may develop multidrug-resistant HIV that can be transmitted to uninfected others. The current analysis conceptualizes social and psychological determinants of adherence to HAART among HIV-positive individuals. The authors propose an information-motivation-behavioral skills (IMB) model of HAART adherence that assumes that adherence-related information, motivation, and behavioral skills are fundamental determinants of adherence to HAART. According to the model, adherence-related information and motivation work through adherence-related behavioral skills to affect adherence to HAART. Empirical support for the IMB model of adherence is presented, and its application in adherence-promotion intervention efforts is discussed.

Sensitivity analysis of static resistance of slender beam under bending

DOE Office of Scientific and Technical Information (OSTI.GOV)

Valeš, Jan

2016-06-08

The paper deals with statical and sensitivity analyses of resistance of simply supported I-beams under bending. The resistance was solved by geometrically nonlinear finite element method in the programme Ansys. The beams are modelled with initial geometrical imperfections following the first eigenmode of buckling. Imperfections were, together with geometrical characteristics of cross section, and material characteristics of steel, considered as random quantities. The method Latin Hypercube Sampling was applied to evaluate statistical and sensitivity resistance analyses.

Changes in the transmission properties of multi-tooth plasmonic nano-filters (multi-TPNFs) caused by geometrical imperfection

NASA Astrophysics Data System (ADS)

Khaksar, A.; Fatemi, H.

2012-08-01

To model the filtering behavior of a multi-tooth plasmonic nano-filter (multi-TPNF), an equivalent circuitry composed of a set of serried impedances is considered. The changes caused in its filtering behavior are proposed as a measuring tool to investigate the effect of the geometrical imperfections occurring during the manufacture of the device. Consequently, the effects of changes in the nominal size of each of the geometrical parameters of a multi-TPNF sample, such as its tooth height, d, its tooth width, w, and the separation between two successive teeth, Δ, on its transmittance are investigated. It is observed that each single tooth of the multi-TPNF and also the waveguide between any of its two successive teeth exhibit a very Fabry-Perot interferometer like behavior. The variation of the transmission spectra of a multi-TPNF whose geometrical parameters are imperfect is compared with the desired filter, and also the effect of the number of geometrically imperfect teeth of the multi-TPNF on the filtering spectra is examined.

The 'Brick Wall' radio loss approximation and the performance of strong channel codes for deep space applications at high data rates

NASA Technical Reports Server (NTRS)

Shambayati, Shervin

2001-01-01

In order to evaluate performance of strong channel codes in presence of imperfect carrier phase tracking for residual carrier BPSK modulation in this paper an approximate 'brick wall' model is developed which is independent of the channel code type for high data rates. It is shown that this approximation is reasonably accurate (less than 0.7dB for low FERs for (1784,1/6) code and less than 0.35dB for low FERs for (5920,1/6) code). Based on the approximation's accuracy, it is concluded that the effects of imperfect carrier tracking are more or less independent of the channel code type for strong channel codes. Therefore, the advantage that one strong channel code has over another with perfect carrier tracking translates to nearly the same advantage under imperfect carrier tracking conditions. This will allow the link designers to incorporate projected channel code performance of strong channel codes into their design tables without worrying about their behavior in the face of imperfect carrier phase tracking.

Decorating surfaces with bidirectional texture functions.

PubMed

Zhou, Kun; Du, Peng; Wang, Lifeng; Matsushita, Yasuyuki; Shi, Jiaoying; Guo, Baining; Shum, Heung-Yeung

2005-01-01

We present a system for decorating arbitrary surfaces with bidirectional texture functions (BTF). Our system generates BTFs in two steps. First, we automatically synthesize a BTF over the target surface from a given BTF sample. Then, we let the user interactively paint BTF patches onto the surface such that the painted patches seamlessly integrate with the background patterns. Our system is based on a patch-based texture synthesis approach known as quilting. We present a graphcut algorithm for BTF synthesis on surfaces and the algorithm works well for a wide variety of BTF samples, including those which present problems for existing algorithms. We also describe a graphcut texture painting algorithm for creating new surface imperfections (e.g., dirt, cracks, scratches) from existing imperfections found in input BTF samples. Using these algorithms, we can decorate surfaces with real-world textures that have spatially-variant reflectance, fine-scale geometry details, and surfaces imperfections. A particularly attractive feature of BTF painting is that it allows us to capture imperfections of real materials and paint them onto geometry models. We demonstrate the effectiveness of our system with examples.

On the Problem of Filtration to an Imperfect Gallery in a Pressureless Bed

NASA Astrophysics Data System (ADS)

Bereslavskii, É. N.; Dudina, L. M.

2018-01-01

The problem of plane steady-state filtration in a pressureless bed to an imperfect gallery in the presence of evaporation from the flow free surface is considered. To study such type of flow, a mixed boundary-value problem of the theory of analytical functions is formulated and solved with application of the Polubarinova-Kochina method. Based on the model suggested, an algorithm for computing the discharge of the gallery and the ordinate of free surface emergence to the impermeable screen is developed. A detailed hydrodynamic analysis of the influence of all physical parameters of the model on the desired filtration characteristics is given.

Shell Buckling Design Criteria Based on Manufacturing Imperfection Signatures

NASA Technical Reports Server (NTRS)

Hilburger, Mark W.; Nemeth, Michael P.; Starnes, James H., Jr.

2004-01-01

An analysis-based approach .for developing shell-buckling design criteria for laminated-composite cylindrical shells that accurately accounts for the effects of initial geometric imperfections is presented. With this approach, measured initial geometric imperfection data from six graphite-epoxy shells are used to determine a manufacturing-process-specific imperfection signature for these shells. This imperfection signature is then used as input into nonlinear finite-element analyses. The imperfection signature represents a "first-approximation" mean imperfection shape that is suitable for developing preliminary-design data. Comparisons of test data and analytical results obtained by using several different imperfection shapes are presented for selected shells. Overall, the results indicate that the analysis-based approach presented for developing reliable preliminary-design criteria has the potential to provide improved, less conservative buckling-load estimates, and to reduce the weight and cost of developing buckling-resistant shell structures.

EPQ model with learning consideration, imperfect production and partial backlogging in fuzzy random environment

NASA Astrophysics Data System (ADS)

Shankar Kumar, Ravi; Goswami, A.

2015-06-01

The article scrutinises the learning effect of the unit production time on optimal lot size for the uncertain and imprecise imperfect production process, wherein shortages are permissible and partially backlogged. Contextually, we contemplate the fuzzy chance of production process shifting from an 'in-control' state to an 'out-of-control' state and re-work facility of imperfect quality of produced items. The elapsed time until the process shifts is considered as a fuzzy random variable, and consequently, fuzzy random total cost per unit time is derived. Fuzzy expectation and signed distance method are used to transform the fuzzy random cost function into an equivalent crisp function. The results are illustrated with the help of numerical example. Finally, sensitivity analysis of the optimal solution with respect to major parameters is carried out.

A spatial model of bird abundance as adjusted for detection probability

USGS Publications Warehouse

Gorresen, P.M.; Mcmillan, G.P.; Camp, R.J.; Pratt, T.K.

2009-01-01

Modeling the spatial distribution of animals can be complicated by spatial and temporal effects (i.e. spatial autocorrelation and trends in abundance over time) and other factors such as imperfect detection probabilities and observation-related nuisance variables. Recent advances in modeling have demonstrated various approaches that handle most of these factors but which require a degree of sampling effort (e.g. replication) not available to many field studies. We present a two-step approach that addresses these challenges to spatially model species abundance. Habitat, spatial and temporal variables were handled with a Bayesian approach which facilitated modeling hierarchically structured data. Predicted abundance was subsequently adjusted to account for imperfect detection and the area effectively sampled for each species. We provide examples of our modeling approach for two endemic Hawaiian nectarivorous honeycreepers: 'i'iwi Vestiaria coccinea and 'apapane Himatione sanguinea. ?? 2009 Ecography.

A Robust State Estimation Framework Considering Measurement Correlations and Imperfect Synchronization

DOE PAGES

Zhao, Junbo; Wang, Shaobu; Mili, Lamine; ...

2018-01-08

Here, this paper develops a robust power system state estimation framework with the consideration of measurement correlations and imperfect synchronization. In the framework, correlations of SCADA and Phasor Measurements (PMUs) are calculated separately through unscented transformation and a Vector Auto-Regression (VAR) model. In particular, PMU measurements during the waiting period of two SCADA measurement scans are buffered to develop the VAR model with robustly estimated parameters using projection statistics approach. The latter takes into account the temporal and spatial correlations of PMU measurements and provides redundant measurements to suppress bad data and mitigate imperfect synchronization. In case where the SCADAmore » and PMU measurements are not time synchronized, either the forecasted PMU measurements or the prior SCADA measurements from the last estimation run are leveraged to restore system observability. Then, a robust generalized maximum-likelihood (GM)-estimator is extended to integrate measurement error correlations and to handle the outliers in the SCADA and PMU measurements. Simulation results that stem from a comprehensive comparison with other alternatives under various conditions demonstrate the benefits of the proposed framework.« less

A Robust State Estimation Framework Considering Measurement Correlations and Imperfect Synchronization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, Junbo; Wang, Shaobu; Mili, Lamine

Here, this paper develops a robust power system state estimation framework with the consideration of measurement correlations and imperfect synchronization. In the framework, correlations of SCADA and Phasor Measurements (PMUs) are calculated separately through unscented transformation and a Vector Auto-Regression (VAR) model. In particular, PMU measurements during the waiting period of two SCADA measurement scans are buffered to develop the VAR model with robustly estimated parameters using projection statistics approach. The latter takes into account the temporal and spatial correlations of PMU measurements and provides redundant measurements to suppress bad data and mitigate imperfect synchronization. In case where the SCADAmore » and PMU measurements are not time synchronized, either the forecasted PMU measurements or the prior SCADA measurements from the last estimation run are leveraged to restore system observability. Then, a robust generalized maximum-likelihood (GM)-estimator is extended to integrate measurement error correlations and to handle the outliers in the SCADA and PMU measurements. Simulation results that stem from a comprehensive comparison with other alternatives under various conditions demonstrate the benefits of the proposed framework.« less

Co-evolution of cooperation and cognition: the impact of imperfect deliberation and context-sensitive intuition

PubMed Central

Kagan, Ari; Rand, David G.

2017-01-01

How does cognitive sophistication impact cooperation? We explore this question using a model of the co-evolution of cooperation and cognition. In our model, agents confront social dilemmas and coordination games, and make decisions using intuition or deliberation. Intuition is automatic and effortless, but relatively (although not necessarily completely) insensitive to context. Deliberation, conversely, is costly but relatively (although not necessarily perfectly) sensitive to context. We find that regardless of the sensitivity of intuition and imperfection of deliberation, deliberating undermines cooperation in social dilemmas, whereas deliberating can increase cooperation in coordination games if intuition is sufficiently sensitive. Furthermore, when coordination games are sufficiently likely, selection favours a strategy whose intuitive response ignores the contextual cues available and cooperates across contexts. Thus, we see how simple cognition can arise from active selection for simplicity, rather than just be forced to be simple due to cognitive constraints. Finally, we find that when deliberation is imperfect, the favoured strategy increases cooperation in social dilemmas (as a result of reducing deliberation) as the benefit of cooperation to the recipient increases. PMID:28330915

The Information–Motivation–Behavioral Skills Model of ART Adherence in a Deep South HIV+ Clinic Sample

PubMed Central

Amico, K. Rivet; Barta, William; Konkle-Parker, Deborah J.; Fisher, Jeffrey D.; Cornman, Deborah H.; Shuper, Paul A.; Fisher, William A.

2011-01-01

High levels of adherence to antiretroviral therapy (ART) are critical to the management of HIV, yet many people living with HIV do not achieve these levels. There is a substantial body of literature regarding correlates of adherence to ART, and theory-based multivariate models of ART adherence are emerging. The current study assessed the determinants of adherence behavior postulated by the Information–Motivation–Behavioral Skills model of ART adherence in a sample of 149 HIV-positive patients in Mississippi. Structural equation modeling indicated that ART-related information correlated with personal and social motivation, and the two sub-areas of motivation were not intercorrelated. In this Deep South sample, being better informed, socially supported, and perceiving fewer negative consequences of adherence were independently related to stronger behavioral skills for taking medications, which in turn associated with self-reported adherence. The IMB model of ART adherence appeared to well characterize the complexities of adherence for this sample. PMID:17876697

The Surgical Care Improvement Project Antibiotic Guidelines: Should We Expect More Than Good Intentions?

PubMed

Schonberger, Robert B; Barash, Paul G; Lagasse, Robert S

2015-08-01

Since 2006, the Surgical Care Improvement Project (SCIP) has promoted 3 perioperative antibiotic recommendations designed to reduce the incidence of surgical site infections. Despite good evidence for the efficacy of these recommendations, the efforts of SCIP have not measurably improved the rates of surgical site infections. We offer 3 arguments as to why SCIP has fallen short of expectations. We then suggest a reorientation of quality improvement efforts to focus less on reporting, and incentivizing adherence to imperfect metrics, and more on creating local and regional quality collaboratives to educate clinicians about how to improve practice. Ultimately, successful quality improvement projects are behavioral interventions that will only succeed to the degree that they motivate individual clinicians, practicing within a particular context, to do the difficult work of identifying failures and iteratively working toward excellence.

The Surgical Care Improvement Project Antibiotic Guidelines: Should We Expect More than Good Intentions?

PubMed Central

Schonberger, Robert B.; Barash, Paul G.; Lagasse, Robert S.

2015-01-01

Since 2006, the Surgical Care Improvement Project (SCIP) has promoted three perioperative antibiotic recommendations designed to reduce the incidence of surgical-site infections. Despite good evidence for the efficacy of these recommendations, SCIP's efforts have not measurably improved rates of surgical site-infections. We offer three arguments as to why SCIP has fallen-short of expectations. We then suggest a reorientation of quality improvement efforts to focus less on reporting, and incentivizing adherence to imperfect metrics, and more on creating local and regional quality collaboratives to educate clinicians about how to improve practice. Ultimately, successful quality improvement projects are behavioral interventions that will only succeed to the degree that they motivate individual clinicians, practicing within a particular context, to do the difficult work of identifying failures and iteratively working toward excellence. PMID:26197373

Patients' mental models and adherence to outpatient physical therapy home exercise programs.

PubMed

Rizzo, Jon

2015-05-01

Within physical therapy, patient adherence usually relates to attending appointments, following advice, and/or undertaking prescribed exercise. Similar to findings for general medical adherence, patient adherence to physical therapy home exercise programs (HEP) is estimated between 35 and 72%. Adherence to HEPs is a multifactorial and poorly understood phenomenon, with no consensus regarding a common theoretical framework that best guides empirical or clinical efforts. Mental models, a construct used to explain behavior and decision-making in the social sciences, may serve as this framework. Mental models comprise an individual's tacit thoughts about how the world works. They include assumptions about new experiences and expectations for the future based on implicit comparisons between current and past experiences. Mental models play an important role in decision-making and guiding actions. This professional theoretical article discusses empirical research demonstrating relationships among mental models, prior experience, and adherence decisions in medical and physical therapy contexts. Specific issues related to mental models and physical therapy patient adherence are discussed, including the importance of articulation of patients' mental models, assessment of patients' mental models that relate to exercise program adherence, discrepancy between patient and provider mental models, and revision of patients' mental models in ways that enhance adherence. The article concludes with practical implications for physical therapists and recommendations for further research to better understand the role of mental models in physical therapy patient adherence behavior.

Empirical validation of the information-motivation-behavioral skills model of diabetes medication adherence: a framework for intervention.

PubMed

Mayberry, Lindsay S; Osborn, Chandra Y

2014-01-01

Suboptimal adherence to diabetes medications is prevalent and associated with unfavorable health outcomes, but it remains unclear what intervention content is necessary to effectively promote medication adherence in diabetes. In other disease contexts, the Information-Motivation-Behavioral skills (IMB) model has effectively explained and promoted medication adherence and thus may have utility in explaining and promoting adherence to diabetes medications. We tested the IMB model's hypotheses in a sample of adults with type 2 diabetes. Participants (N = 314) completed an interviewer-administered survey and A1C test. Structural equation models tested the effects of diabetes medication adherence-related information, motivation, and behavioral skills on medication adherence and the effect of medication adherence on A1C. The IMB elements explained 41% of the variance in adherence, and adherence explained 9% of the variance in A1C. As predicted, behavioral skills had a direct effect on adherence (β = 0.59; P < 0.001) and mediated the effects of information (indirect effect 0.08 [0.01-0.15]) and motivation (indirect effect 0.12 [0.05-0.20]) on adherence. Medication adherence significantly predicted glycemic control (β = -0.30; P < 0.001). Neither insulin status nor regimen complexity was associated with adherence, and neither moderated associations between the IMB constructs and adherence. The results support the IMB model's predictions and identify modifiable and intervenable determinants of diabetes medication adherence. Medication adherence promotion interventions may benefit from content targeting patients' medication adherence-related information, motivation, and behavioral skills and assessing the degree to which change in these determinants leads to changes in medication adherence behavior.

Opponent Classification in Poker

NASA Astrophysics Data System (ADS)

Ahmad, Muhammad Aurangzeb; Elidrisi, Mohamed

Modeling games has a long history in the Artificial Intelligence community. Most of the games that have been considered solved in AI are perfect information games. Imperfect information games like Poker and Bridge represent a domain where there is a great deal of uncertainty involved and additional challenges with respect to modeling the behavior of the opponent etc. Techniques developed for playing imperfect games also have many real world applications like repeated online auctions, human computer interaction, opponent modeling for military applications etc. In this paper we explore different techniques for playing poker, the core of these techniques is opponent modeling via classifying the behavior of opponent according to classes provided by domain experts. We utilize windows of full observation in the game to classify the opponent. In Poker, the behavior of an opponent is classified into four standard poker-playing styles based on a subjective function.

A testing-coverage software reliability model considering fault removal efficiency and error generation.

PubMed

Li, Qiuying; Pham, Hoang

2017-01-01

In this paper, we propose a software reliability model that considers not only error generation but also fault removal efficiency combined with testing coverage information based on a nonhomogeneous Poisson process (NHPP). During the past four decades, many software reliability growth models (SRGMs) based on NHPP have been proposed to estimate the software reliability measures, most of which have the same following agreements: 1) it is a common phenomenon that during the testing phase, the fault detection rate always changes; 2) as a result of imperfect debugging, fault removal has been related to a fault re-introduction rate. But there are few SRGMs in the literature that differentiate between fault detection and fault removal, i.e. they seldom consider the imperfect fault removal efficiency. But in practical software developing process, fault removal efficiency cannot always be perfect, i.e. the failures detected might not be removed completely and the original faults might still exist and new faults might be introduced meanwhile, which is referred to as imperfect debugging phenomenon. In this study, a model aiming to incorporate fault introduction rate, fault removal efficiency and testing coverage into software reliability evaluation is developed, using testing coverage to express the fault detection rate and using fault removal efficiency to consider the fault repair. We compare the performance of the proposed model with several existing NHPP SRGMs using three sets of real failure data based on five criteria. The results exhibit that the model can give a better fitting and predictive performance.

Investigation on imperfection sensitivity of composite cylindrical shells using the nonlinearity reduction technique and the polynomial chaos method

NASA Astrophysics Data System (ADS)

Liang, Ke; Sun, Qin; Liu, Xiaoran

2018-05-01

The theoretical buckling load of a perfect cylinder must be reduced by a knock-down factor to account for structural imperfections. The EU project DESICOS proposed a new robust design for imperfection-sensitive composite cylindrical shells using the combination of deterministic and stochastic simulations, however the high computational complexity seriously affects its wider application in aerospace structures design. In this paper, the nonlinearity reduction technique and the polynomial chaos method are implemented into the robust design process, to significantly lower computational costs. The modified Newton-type Koiter-Newton approach which largely reduces the number of degrees of freedom in the nonlinear finite element model, serves as the nonlinear buckling solver to trace the equilibrium paths of geometrically nonlinear structures efficiently. The non-intrusive polynomial chaos method provides the buckling load with an approximate chaos response surface with respect to imperfections and uses buckling solver codes as black boxes. A fast large-sample study can be applied using the approximate chaos response surface to achieve probability characteristics of buckling loads. The performance of the method in terms of reliability, accuracy and computational effort is demonstrated with an unstiffened CFRP cylinder.

Buckling of circular cylindrical shells under dynamically applied axial loads

NASA Technical Reports Server (NTRS)

Tulk, J. D.

1972-01-01

A theoretical and experimental study was made of the buckling characteristics of perfect and imperfect circular cylindrical shells subjected to dynamic axial loading. Experimental data included dynamic buckling loads (124 data points), high speed photographs of buckling mode shapes and observations of the dynamic stability of shells subjected to rapidly applied sub-critical loads. A mathematical model was developed to describe the dynamic behavior of perfect and imperfect shells. This model was based on the Donnell-Von Karman compatibility and equilibrium equations and had a wall deflection function incorporating five separate modes of deflection. Close agreement between theory and experiment was found for both dynamic buckling strength and buckling mode shapes.

Comparison of sensitivity and resolution load sensor at various configuration polymer optical fiber

NASA Astrophysics Data System (ADS)

Arifin, A.; Yusran, Miftahuddin, Abdullah, Bualkar; Tahir, Dahlang

2017-01-01

This study uses a load sensor with a macro-bending on polymer optical fiber loop model which is placed between two plates with a buffer spring. The load sensor with light intensity modulation principle is an infrared LED emits light through the polymer optical fiber then received by the phototransistor and amplifier. Output voltage from the amplifier continued to arduino sequence and displayed on the computer. Load augment on the sensor resulted in an increase of curvature on polymer optical fibers that can cause power losses gets bigger too. This matter will result in the intensity of light that received by phototransistor getting smaller, so that the output voltage that ligable on computer will be getting smaller too. The sensitivity and resolution load sensors analyzed based on configuration with various amount of loops, imperfection on the jacket, and imperfection at the cladding and core of polymer optical fiber. The results showed that the augment on the amount of load, imperfection on the jacket and imperfection on the sheath and core polymer optical fiber can improve the sensitivity and resolution of the load sensor. The best sensors resolution obtained on the number of loops 4 with imperfection 8 on the core and cladding polymer optical fiber that is 0.037 V/N and 0,026 N. The advantages of the load sensor based on polymers optical fiber are easy to make, low cost and simple to use measurement methods.

Sequential Inverse Problems Bayesian Principles and the Logistic Map Example

NASA Astrophysics Data System (ADS)

Duan, Lian; Farmer, Chris L.; Moroz, Irene M.

2010-09-01

Bayesian statistics provides a general framework for solving inverse problems, but is not without interpretation and implementation problems. This paper discusses difficulties arising from the fact that forward models are always in error to some extent. Using a simple example based on the one-dimensional logistic map, we argue that, when implementation problems are minimal, the Bayesian framework is quite adequate. In this paper the Bayesian Filter is shown to be able to recover excellent state estimates in the perfect model scenario (PMS) and to distinguish the PMS from the imperfect model scenario (IMS). Through a quantitative comparison of the way in which the observations are assimilated in both the PMS and the IMS scenarios, we suggest that one can, sometimes, measure the degree of imperfection.

Mathematical Analysis of an SIQR Influenza Model with Imperfect Quarantine.

PubMed

Erdem, Mustafa; Safan, Muntaser; Castillo-Chavez, Carlos

2017-07-01

The identification of mechanisms responsible for recurrent epidemic outbreaks, such as age structure, cross-immunity and variable delays in the infective classes, has challenged and fascinated epidemiologists and mathematicians alike. This paper addresses, motivated by mathematical work on influenza models, the impact of imperfect quarantine on the dynamics of SIR-type models. A susceptible-infectious-quarantine-recovered (SIQR) model is formulated with quarantined individuals altering the transmission dynamics process through their possibly reduced ability to generate secondary cases of infection. Mathematical and numerical analyses of the model of the equilibria and their stability have been carried out. Uniform persistence of the model has been established. Numerical simulations show that the model supports Hopf bifurcation as a function of the values of the quarantine effectiveness and other parameters. The upshot of this work is somewhat surprising since it is shown that SIQR model oscillatory behavior, as shown by multiple researchers, is in fact not robust to perturbations in the quarantine regime.

Stability of continuous-time quantum filters with measurement imperfections

NASA Astrophysics Data System (ADS)

Amini, H.; Pellegrini, C.; Rouchon, P.

2014-07-01

The fidelity between the state of a continuously observed quantum system and the state of its associated quantum filter, is shown to be always a submartingale. The observed system is assumed to be governed by a continuous-time Stochastic Master Equation (SME), driven simultaneously by Wiener and Poisson processes and that takes into account incompleteness and errors in measurements. This stability result is the continuous-time counterpart of a similar stability result already established for discrete-time quantum systems and where the measurement imperfections are modelled by a left stochastic matrix.

Several comparison result of two types of equilibrium (Pareto Schemes and Stackelberg Scheme) of game theory approach in probabilistic vendor – buyer supply chain system with imperfect quality

NASA Astrophysics Data System (ADS)

Setiawan, R.

2018-05-01

In this paper, Economic Order Quantity (EOQ) of the vendor-buyer supply-chain model under a probabilistic condition with imperfect quality items has been analysed. The analysis is delivered using two concepts in game theory approach, which is Stackelberg equilibrium and Pareto Optimal, under non-cooperative and cooperative games, respectively. Another result is getting acomparison of theoptimal result between integrated scheme and game theory approach based on analytical and numerical result using appropriate simulation data.

Chaos in an imperfectly premixed model combustor.

PubMed

Kabiraj, Lipika; Saurabh, Aditya; Karimi, Nader; Sailor, Anna; Mastorakos, Epaminondas; Dowling, Ann P; Paschereit, Christian O

2015-02-01

This article reports nonlinear bifurcations observed in a laboratory scale, turbulent combustor operating under imperfectly premixed mode with global equivalence ratio as the control parameter. The results indicate that the dynamics of thermoacoustic instability correspond to quasi-periodic bifurcation to low-dimensional, deterministic chaos, a route that is common to a variety of dissipative nonlinear systems. The results support the recent identification of bifurcation scenarios in a laminar premixed flame combustor (Kabiraj et al., Chaos: Interdiscip. J. Nonlinear Sci. 22, 023129 (2012)) and extend the observation to a practically relevant combustor configuration.

A homotopy analysis method for the option pricing PDE in illiquid markets

NASA Astrophysics Data System (ADS)

E-Khatib, Youssef

2012-09-01

One of the shortcomings of the Black and Scholes model on option pricing is the assumption that trading the underlying asset does not affect the underlying asset price. This can happen in perfectly liquid markets and it is evidently not viable in markets with imperfect liquidity (illiquid markets). It is well-known that markets with imperfect liquidity are more realistic. Thus, the presence of price impact while studying options is very important. This paper investigates a solution for the option pricing PDE in illiquid markets using the homotopy analysis method.

Hierarchical spatial models of abundance and occurrence from imperfect survey data

USGS Publications Warehouse

Royle, J. Andrew; Kery, M.; Gautier, R.; Schmid, Hans

2007-01-01

Many estimation and inference problems arising from large-scale animal surveys are focused on developing an understanding of patterns in abundance or occurrence of a species based on spatially referenced count data. One fundamental challenge, then, is that it is generally not feasible to completely enumerate ('census') all individuals present in each sample unit. This observation bias may consist of several components, including spatial coverage bias (not all individuals in the Population are exposed to sampling) and detection bias (exposed individuals may go undetected). Thus, observations are biased for the state variable (abundance, occupancy) that is the object of inference. Moreover, data are often sparse for most observation locations, requiring consideration of methods for spatially aggregating or otherwise combining sparse data among sample units. The development of methods that unify spatial statistical models with models accommodating non-detection is necessary to resolve important spatial inference problems based on animal survey data. In this paper, we develop a novel hierarchical spatial model for estimation of abundance and occurrence from survey data wherein detection is imperfect. Our application is focused on spatial inference problems in the Swiss Survey of Common Breeding Birds. The observation model for the survey data is specified conditional on the unknown quadrat population size, N(s). We augment the observation model with a spatial process model for N(s), describing the spatial variation in abundance of the species. The model includes explicit sources of variation in habitat structure (forest, elevation) and latent variation in the form of a correlated spatial process. This provides a model-based framework for combining the spatially referenced samples while at the same time yielding a unified treatment of estimation problems involving both abundance and occurrence. We provide a Bayesian framework for analysis and prediction based on the integrated likelihood, and we use the model to obtain estimates of abundance and occurrence maps for the European Jay (Garrulus glandarius), a widespread, elusive, forest bird. The naive national abundance estimate ignoring imperfect detection and incomplete quadrat coverage was 77 766 territories. Accounting for imperfect detection added approximately 18 000 territories, and adjusting for coverage bias added another 131 000 territories to yield a fully corrected estimate of the national total of about 227 000 territories. This is approximately three times as high as previous estimates that assume every territory is detected in each quadrat.

Characterizing the effect of growth conditions and crystal habit on the distribution of imperfections amongst populations of crystals

NASA Astrophysics Data System (ADS)

Price, C. J.

1993-03-01

The distribution of gross imperfections amongst populations of copper sulphate pentahydrate crystals grown under different conditions of purity and temperature are examined. The frequency of imperfection increases with decreasing crystal size. The nature of the imperfections vary with growth temperature and impurities present.

Virulence evolution in response to anti-infection resistance: toxic food plants can select for virulent parasites of monarch butterflies.

PubMed

de Roode, J C; de Castillejo, C Lopez Fernandez; Faits, T; Alizon, S

2011-04-01

Host resistance to parasites can come in two main forms: hosts may either reduce the probability of parasite infection (anti-infection resistance) or reduce parasite growth after infection has occurred (anti-growth resistance). Both resistance mechanisms are often imperfect, meaning that they do not fully prevent or clear infections. Theoretical work has suggested that imperfect anti-growth resistance can select for higher parasite virulence by favouring faster-growing and more virulent parasites that overcome this resistance. In contrast, imperfect anti-infection resistance is thought not to select for increased parasite virulence, because it is assumed that it reduces the number of hosts that become infected, but not the fitness of parasites in successfully infected hosts. Here, we develop a theoretical model to show that anti-infection resistance can in fact select for higher virulence when such resistance reduces the effective parasite dose that enters a host. Our model is based on a monarch butterfly-parasite system in which larval food plants confer resistance to the monarch host. We carried out an experiment and showed that this environmental resistance is most likely a form of anti-infection resistance, through which toxic food plants reduce the effective dose of parasites that initiates an infection. We used these results to build a mathematical model to investigate the evolutionary consequences of food plant-induced resistance. Our model shows that when the effective infectious dose is reduced, parasites can compensate by evolving a higher per-parasite growth rate, and consequently a higher intrinsic virulence. Our results are relevant to many insect host-parasite systems, in which larval food plants often confer imperfect anti-infection resistance. Our results also suggest that - for parasites where the infectious dose affects the within-host dynamics - vaccines that reduce the effective infectious dose can select for increased parasite virulence. © 2011 The Authors. Journal of Evolutionary Biology © 2011 European Society For Evolutionary Biology.

Numerical research on the lateral global buckling characteristics of a high temperature and pressure pipeline with two initial imperfections

PubMed Central

Liu, Wenbin; Liu, Aimin

2018-01-01

With the exploitation of offshore oil and gas gradually moving to deep water, higher temperature differences and pressure differences are applied to the pipeline system, making the global buckling of the pipeline more serious. For unburied deep-water pipelines, the lateral buckling is the major buckling form. The initial imperfections widely exist in the pipeline system due to manufacture defects or the influence of uneven seabed, and the distribution and geometry features of initial imperfections are random. They can be divided into two kinds based on shape: single-arch imperfections and double-arch imperfections. This paper analyzed the global buckling process of a pipeline with 2 initial imperfections by using a numerical simulation method and revealed how the ratio of the initial imperfection’s space length to the imperfection’s wavelength and the combination of imperfections affects the buckling process. The results show that a pipeline with 2 initial imperfections may suffer the superposition of global buckling. The growth ratios of buckling displacement, axial force and bending moment in the superposition zone are several times larger than no buckling superposition pipeline. The ratio of the initial imperfection’s space length to the imperfection’s wavelength decides whether a pipeline suffers buckling superposition. The potential failure point of pipeline exhibiting buckling superposition is as same as the no buckling superposition pipeline, but the failure risk of pipeline exhibiting buckling superposition is much higher. The shape and direction of two nearby imperfections also affects the failure risk of pipeline exhibiting global buckling superposition. The failure risk of pipeline with two double-arch imperfections is higher than pipeline with two single-arch imperfections. PMID:29554123

A nonlinear interface model applied to masonry structures

NASA Astrophysics Data System (ADS)

Lebon, Frédéric; Raffa, Maria Letizia; Rizzoni, Raffaella

2015-12-01

In this paper, a new imperfect interface model is presented. The model includes finite strains, micro-cracks and smooth roughness. The model is consistently derived by coupling a homogenization approach for micro-cracked media and arguments of asymptotic analysis. The model is applied to brick/mortar interfaces. Numerical results are presented.

On the importance of incorporating sampling weights in occupancy model estimation

EPA Science Inventory

Occupancy models are used extensively to assess wildlife-habitat associations and to predict species distributions across large geographic regions. Occupancy models were developed as a tool to properly account for imperfect detection of a species. Current guidelines on survey des...

Development of a Model Based Technique for Gear Diagnostics using the Wigner-Ville method

NASA Technical Reports Server (NTRS)

Choy, F.; Xu, A.; Polyshchuk, V.

1997-01-01

Imperfections in gear tooth geometry often result from errors in the manufacturing process or excessive material wear during operation. Such faults in the gear tooth geometry can result in large vibrations in the transmission system, and, in some cases, may lead to early failure of the gear transmission system. This report presents the study of the effects of imperfection in gear tooth geometry on the dynamic characteristics of a gear transmission system. The faults in the gear tooth geometry are modeled numerically as the deviation of the tooth profile from its original involute geometry. The changes in gear mesh stiffness due to various profile and pattern variations are evaluated numerically. The resulting changes in the mesh stiffness are incorporated into a computer code to simulate the dynamics of the gear transmission system. A parametric study is performed to examine the sensitivity of gear tooth geometry imperfections on the vibration of a gear transmission system. The parameters variations in this study consist of the magnitude of the imperfection, the pattern of the profile variation, and the total number of teeth affected. Numerical results from the dynamic simulations are examined in both the time and the frequency domains. A joint time-frequency analysis procedure using the Wigner-Ville Distribution is also introduced to identify the location of the damaged tooth from the vibration signature. Numerical simulations of the system dynamics with gear faults were compared to experimental results. An optimal tracker was introduced to quantify the level of damage in the gear mesh system. Conclusions are drawn from the results of this numerical study.

Plastic buckling. [post-bifurcation and imperfection sensitivity

NASA Technical Reports Server (NTRS)

Hutchinson, J. W.

1974-01-01

The present article is concerned mainly with the post-bifurcation and imperfection-sensitivity aspects of plastic buckling. A simple two-degree-of-freedom model is used to introduce post-bifurcation behavior and a second model illustrates features of the behavior of continuous solids and structures. Hill's bifurcation criterion for a class of three-dimensional solids is applied to the Donnell-Mushtari-Vlasov (DMV) theory of plates and shells. A general treatment of the initial post-bifurcation behavior of plates and shells is given within the context of the DMV theory. This is illustrated by problems involving columns and circular plates under radial compression. Numerical results are given for a column under axial compression, a circular plate under radial compression, and spherical and cylindrical shells.

Randomness determines practical security of BB84 quantum key distribution.

PubMed

Li, Hong-Wei; Yin, Zhen-Qiang; Wang, Shuang; Qian, Yong-Jun; Chen, Wei; Guo, Guang-Can; Han, Zheng-Fu

2015-11-10

Unconditional security of the BB84 quantum key distribution protocol has been proved by exploiting the fundamental laws of quantum mechanics, but the practical quantum key distribution system maybe hacked by considering the imperfect state preparation and measurement respectively. Until now, different attacking schemes have been proposed by utilizing imperfect devices, but the general security analysis model against all of the practical attacking schemes has not been proposed. Here, we demonstrate that the general practical attacking schemes can be divided into the Trojan horse attack, strong randomness attack and weak randomness attack respectively. We prove security of BB84 protocol under randomness attacking models, and these results can be applied to guarantee the security of the practical quantum key distribution system.

Randomness determines practical security of BB84 quantum key distribution

PubMed Central

Li, Hong-Wei; Yin, Zhen-Qiang; Wang, Shuang; Qian, Yong-Jun; Chen, Wei; Guo, Guang-Can; Han, Zheng-Fu

2015-01-01

Unconditional security of the BB84 quantum key distribution protocol has been proved by exploiting the fundamental laws of quantum mechanics, but the practical quantum key distribution system maybe hacked by considering the imperfect state preparation and measurement respectively. Until now, different attacking schemes have been proposed by utilizing imperfect devices, but the general security analysis model against all of the practical attacking schemes has not been proposed. Here, we demonstrate that the general practical attacking schemes can be divided into the Trojan horse attack, strong randomness attack and weak randomness attack respectively. We prove security of BB84 protocol under randomness attacking models, and these results can be applied to guarantee the security of the practical quantum key distribution system. PMID:26552359

Randomness determines practical security of BB84 quantum key distribution

NASA Astrophysics Data System (ADS)

Li, Hong-Wei; Yin, Zhen-Qiang; Wang, Shuang; Qian, Yong-Jun; Chen, Wei; Guo, Guang-Can; Han, Zheng-Fu

2015-11-01

Unconditional security of the BB84 quantum key distribution protocol has been proved by exploiting the fundamental laws of quantum mechanics, but the practical quantum key distribution system maybe hacked by considering the imperfect state preparation and measurement respectively. Until now, different attacking schemes have been proposed by utilizing imperfect devices, but the general security analysis model against all of the practical attacking schemes has not been proposed. Here, we demonstrate that the general practical attacking schemes can be divided into the Trojan horse attack, strong randomness attack and weak randomness attack respectively. We prove security of BB84 protocol under randomness attacking models, and these results can be applied to guarantee the security of the practical quantum key distribution system.

"It's important to take your medication everyday okay?" An evaluation of counselling by lay counsellors for ARV adherence support in the Western Cape, South Africa.

PubMed

Dewing, S; Mathews, C; Schaay, N; Cloete, A; Louw, J; Simbayi, L

2013-01-01

There is growing interest in standard care programmes for antiretroviral (ARV) adherence support. In South Africa, individual counselling following ARV initiation is a main strategy for supporting adherence in the public sector. Egan's client-centred "Skilled Helper" counselling model is the predominant model used in HIV counselling in this context. This study evaluated counselling delivered by lay ARV adherence counsellors in Cape Town in terms of adherence to Egan's model. Thirty-eight transcripts of counselling sessions with non-adherent patients were analysed based on the methods of content analysis. These sessions were conducted by 30 counsellors. Generally counsellors' practice adhered neither to Egan's model nor a client-centred approach. Inconsistent with evidence-based approaches to counselling for ARV adherence support, counsellors mainly used information-giving and advice as strategies for addressing clients' non-adherence. Recommendations for improving practice are made. The question as to how appropriate strategies from developed countries are for this setting is also raised.

A multiple-scales model of the shock-cell structure of imperfectly expanded supersonic jets

NASA Technical Reports Server (NTRS)

Tam, C. K. W.; Jackson, J. A.; Seiner, J. M.

1985-01-01

The present investigation is concerned with the development of an analytical model of the quasi-periodic shock-cell structure of an imperfectly expanded supersonic jet. The investigation represents a part of a program to develop a mathematical theory of broadband shock-associated noise of supersonic jets. Tam and Tanna (1982) have suggested that this type of noise is generated by the weak interaction between the quasi-periodic shock cells and the downstream-propagating large turbulence structures in the mixing layer of the jet. In the model developed in this paper, the effect of turbulence in the mixing layer of the jet is simulated by the addition of turbulent eddy-viscosity terms to the momentum equation. Attention is given to the mean-flow profile and the numerical solution, and a comparison of the numerical results with experimental data.

A testing-coverage software reliability model considering fault removal efficiency and error generation

PubMed Central

Li, Qiuying; Pham, Hoang

2017-01-01

In this paper, we propose a software reliability model that considers not only error generation but also fault removal efficiency combined with testing coverage information based on a nonhomogeneous Poisson process (NHPP). During the past four decades, many software reliability growth models (SRGMs) based on NHPP have been proposed to estimate the software reliability measures, most of which have the same following agreements: 1) it is a common phenomenon that during the testing phase, the fault detection rate always changes; 2) as a result of imperfect debugging, fault removal has been related to a fault re-introduction rate. But there are few SRGMs in the literature that differentiate between fault detection and fault removal, i.e. they seldom consider the imperfect fault removal efficiency. But in practical software developing process, fault removal efficiency cannot always be perfect, i.e. the failures detected might not be removed completely and the original faults might still exist and new faults might be introduced meanwhile, which is referred to as imperfect debugging phenomenon. In this study, a model aiming to incorporate fault introduction rate, fault removal efficiency and testing coverage into software reliability evaluation is developed, using testing coverage to express the fault detection rate and using fault removal efficiency to consider the fault repair. We compare the performance of the proposed model with several existing NHPP SRGMs using three sets of real failure data based on five criteria. The results exhibit that the model can give a better fitting and predictive performance. PMID:28750091

Spanish Imperfect Revisited: Exploring L1 Influence in the Reassembly of Imperfective Features onto New L2 Forms

ERIC Educational Resources Information Center

Domínguez, Laura; Arche, María J.; Myles, Florence

2017-01-01

This study investigates the acquisition of the Spanish Imperfect by 60 English learners of Spanish at three different proficiency levels (beginner, intermediate and advanced). Two oral production tasks and one interpretation task show that although the Imperfect is used from early on, the full array of interpretations associated with this form…

Markov Mixed Effects Modeling Using Electronic Adherence Monitoring Records Identifies Influential Covariates to HIV Preexposure Prophylaxis.

PubMed

Madrasi, Kumpal; Chaturvedula, Ayyappa; Haberer, Jessica E; Sale, Mark; Fossler, Michael J; Bangsberg, David; Baeten, Jared M; Celum, Connie; Hendrix, Craig W

2017-05-01

Adherence is a major factor in the effectiveness of preexposure prophylaxis (PrEP) for HIV prevention. Modeling patterns of adherence helps to identify influential covariates of different types of adherence as well as to enable clinical trial simulation so that appropriate interventions can be developed. We developed a Markov mixed-effects model to understand the covariates influencing adherence patterns to daily oral PrEP. Electronic adherence records (date and time of medication bottle cap opening) from the Partners PrEP ancillary adherence study with a total of 1147 subjects were used. This study included once-daily dosing regimens of placebo, oral tenofovir disoproxil fumarate (TDF), and TDF in combination with emtricitabine (FTC), administered to HIV-uninfected members of serodiscordant couples. One-coin and first- to third-order Markov models were fit to the data using NONMEM ® 7.2. Model selection criteria included objective function value (OFV), Akaike information criterion (AIC), visual predictive checks, and posterior predictive checks. Covariates were included based on forward addition (α = 0.05) and backward elimination (α = 0.001). Markov models better described the data than 1-coin models. A third-order Markov model gave the lowest OFV and AIC, but the simpler first-order model was used for covariate model building because no additional benefit on prediction of target measures was observed for higher-order models. Female sex and older age had a positive impact on adherence, whereas Sundays, sexual abstinence, and sex with a partner other than the study partner had a negative impact on adherence. Our findings suggest adherence interventions should consider the role of these factors. © 2016, The American College of Clinical Pharmacology.

Combination of uncertainty theories and decision-aiding methods for natural risk management in a context of imperfect information

NASA Astrophysics Data System (ADS)

Tacnet, Jean-Marc; Dupouy, Guillaume; Carladous, Simon; Dezert, Jean; Batton-Hubert, Mireille

2017-04-01

In mountain areas, natural phenomena such as snow avalanches, debris-flows and rock-falls, put people and objects at risk with sometimes dramatic consequences. Risk is classically considered as a combination of hazard, the combination of the intensity and frequency of the phenomenon, and vulnerability which corresponds to the consequences of the phenomenon on exposed people and material assets. Risk management consists in identifying the risk level as well as choosing the best strategies for risk prevention, i.e. mitigation. In the context of natural phenomena in mountainous areas, technical and scientific knowledge is often lacking. Risk management decisions are therefore based on imperfect information. This information comes from more or less reliable sources ranging from historical data, expert assessments, numerical simulations etc. Finally, risk management decisions are the result of complex knowledge management and reasoning processes. Tracing the information and propagating information quality from data acquisition to decisions are therefore important steps in the decision-making process. One major goal today is therefore to assist decision-making while considering the availability, quality and reliability of information content and sources. A global integrated framework is proposed to improve the risk management process in a context of information imperfection provided by more or less reliable sources: uncertainty as well as imprecision, inconsistency and incompleteness are considered. Several methods are used and associated in an original way: sequential decision context description, development of specific multi-criteria decision-making methods, imperfection propagation in numerical modeling and information fusion. This framework not only assists in decision-making but also traces the process and evaluates the impact of information quality on decision-making. We focus and present two main developments. The first one relates to uncertainty and imprecision propagation in numerical modeling using both classical Monte-Carlo probabilistic approach and also so-called Hybrid approach using possibility theory. Second approach deals with new multi-criteria decision-making methods which consider information imperfection, source reliability, importance and conflict, using fuzzy sets as well as possibility and belief function theories. Implemented methods consider information imperfection propagation and information fusion in total aggregation methods such as AHP (Saaty, 1980) or partial aggregation methods such as the Electre outranking method (see Soft Electre Tri ) or decisions in certain but also risky or uncertain contexts (see new COWA-ER and FOWA-ER- Cautious and Fuzzy Ordered Weighted Averaging-Evidential Reasoning). For example, the ER-MCDA methodology considers expert assessment as a multi-criteria decision process based on imperfect information provided by more or less heterogeneous, reliable and conflicting sources: it mixes AHP, fuzzy sets theory, possibility theory and belief function theory using DSmT (Dezert-Smarandache Theory) framework which provides powerful fusion rules.

Method and Apparatus for Evaluating Multilayer Objects for Imperfections

NASA Technical Reports Server (NTRS)

Heyman, Joseph S. (Inventor); Abedin, Nurul (Inventor); Sun, Kuen J. (Inventor)

1999-01-01

A multilayer object having multiple layers arranged in a stacking direction is evaluated for imperfections such as voids, delaminations and microcracks. First. an acoustic wave is transmitted into the object in the stacking direction via an appropriate transducer/waveguide combination. The wave propagates through the multilayer object and is received by another transducer/waveguide combination preferably located on the same surface as the transmitting combination. The received acoustic wave is correlated with the presence or absence of imperfections by, e.g., generating pulse echo signals indicative of the received acoustic wave. wherein the successive signals form distinct groups over time. The respective peak amplitudes of each group are sampled and curve fit to an exponential curve. wherein a substantial fit of approximately 80-90% indicates an absence of imperfections and a significant deviation indicates the presence of imperfections. Alternatively, the time interval between distinct groups can be measured. wherein equal intervals indicate the absence of imperfections and unequal intervals indicate the presence of imperfections.

Method and apparatus for evaluating multilayer objects for imperfections

NASA Technical Reports Server (NTRS)

Heyman, Joseph S. (Inventor); Abedin, Nurul (Inventor); Sun, Kuen J. (Inventor)

1997-01-01

A multilayer object having multiple layers arranged in a stacking direction is evaluated for imperfections such as voids, delaminations and microcracks. First, an acoustic wave is transmitted into the object in the stacking direction via an appropriate transducer/waveguide combination. The wave propagates through the multilayer object and is received by another transducer/waveguide combination preferably located on the same surface as the transmitting combination. The received acoustic wave is correlated with the presence or absence of imperfections by, e.g., generating pulse echo signals indicative of the received acoustic wave, wherein the successive signals form distinct groups over time. The respective peak amplitudes of each group are sampled and curve fit to an exponential curve, wherein a substantial fit of approximately 80-90% indicates an absence of imperfections and a significant deviation indicates the presence of imperfections. Alternatively, the time interval between distinct groups can be measured, wherein equal intervals indicate the absence of imperfections and unequal intervals indicate the presence of imperfections.

Modeling the internal dynamics of energy and mass transfer in an imperfectly mixed ventilated airspace.

PubMed

Janssens, K; Van Brecht, A; Zerihun Desta, T; Boonen, C; Berckmans, D

2004-06-01

The present paper outlines a modeling approach, which has been developed to model the internal dynamics of heat and moisture transfer in an imperfectly mixed ventilated airspace. The modeling approach, which combines the classical heat and moisture balance differential equations with the use of experimental time-series data, provides a physically meaningful description of the process and is very useful for model-based control purposes. The paper illustrates how the modeling approach has been applied to a ventilated laboratory test room with internal heat and moisture production. The results are evaluated and some valuable suggestions for future research are forwarded. The modeling approach outlined in this study provides an ideal form for advanced model-based control system design. The relatively low number of parameters makes it well suited for model-based control purposes, as a limited number of identification experiments is sufficient to determine these parameters. The model concept provides information about the air quality and airflow pattern in an arbitrary building. By using this model as a simulation tool, the indoor air quality and airflow pattern can be optimized.

Robust THP Transceiver Designs for Multiuser MIMO Downlink with Imperfect CSIT

NASA Astrophysics Data System (ADS)

Ubaidulla, P.; Chockalingam, A.

2009-12-01

We present robust joint nonlinear transceiver designs for multiuser multiple-input multiple-output (MIMO) downlink in the presence of imperfections in the channel state information at the transmitter (CSIT). The base station (BS) is equipped with multiple transmit antennas, and each user terminal is equipped with one or more receive antennas. The BS employs Tomlinson-Harashima precoding (THP) for interuser interference precancellation at the transmitter. We consider robust transceiver designs that jointly optimize the transmit THP filters and receive filter for two models of CSIT errors. The first model is a stochastic error (SE) model, where the CSIT error is Gaussian-distributed. This model is applicable when the CSIT error is dominated by channel estimation error. In this case, the proposed robust transceiver design seeks to minimize a stochastic function of the sum mean square error (SMSE) under a constraint on the total BS transmit power. We propose an iterative algorithm to solve this problem. The other model we consider is a norm-bounded error (NBE) model, where the CSIT error can be specified by an uncertainty set. This model is applicable when the CSIT error is dominated by quantization errors. In this case, we consider a worst-case design. For this model, we consider robust (i) minimum SMSE, (ii) MSE-constrained, and (iii) MSE-balancing transceiver designs. We propose iterative algorithms to solve these problems, wherein each iteration involves a pair of semidefinite programs (SDPs). Further, we consider an extension of the proposed algorithm to the case with per-antenna power constraints. We evaluate the robustness of the proposed algorithms to imperfections in CSIT through simulation, and show that the proposed robust designs outperform nonrobust designs as well as robust linear transceiver designs reported in the recent literature.

PROBABILISTIC CHARACTERIZATION OF ATMOSPHERIC TRANSPORT AND DIFFUSION

EPA Science Inventory

The observed scatter of observations about air quality model predictions stems from a combination of naturally occurring stochastic variations that are impossible for any model to explicitly simulate and variations arising from limitations in our knowledge and from imperfect inpu...

Size-dependent bending modulus of nanotubes induced by the imperfect boundary conditions

PubMed Central

Zhang, Jin

2016-01-01

The size-dependent bending modulus of nanotubes, which was widely observed in most existing three-point bending experiments [e.g., J. Phys. Chem. B 117, 4618–4625 (2013)], has been tacitly assumed to originate from the shear effect. In this paper, taking boron nitride nanotubes as an example, we directly measured the shear effect by molecular dynamics (MD) simulations and found that the shear effect is not the major factor responsible for the observed size-dependent bending modulus of nanotubes. To further explain the size-dependence phenomenon, we abandoned the assumption of perfect boundary conditions (BCs) utilized in the aforementioned experiments and studied the influence of the BCs on the bending modulus of nanotubes based on MD simulations. The results show that the imperfect BCs also make the bending modulus of nanotubes size-dependent. Moreover, the size-dependence phenomenon induced by the imperfect BCs is much more significant than that induced by the shear effect, which suggests that the imperfect BC is a possible physical origin that leads to the strong size-dependence of the bending modulus found in the aforementioned experiments. To capture the physics behind the MD simulation results, a beam model with the general BCs is proposed and found to fit the experimental data very well. PMID:27941866

Positive provider interactions, adherence self-efficacy, and adherence to antiretroviral medications among HIV infected adults: A mediation model

PubMed Central

Johnson, Mallory O.; Chesney, Margaret A.; Goldstein, Rise B.; Remien, Robert H.; Catz, Sheryl; Gore-Felton, Cheryl; Charlebois, Edwin; Morin, Stephen F.

2008-01-01

Adherence to antiretroviral (ARV) therapy for HIV infection is critical for maximum benefit from treatment and for the prevention of HIV-related complications. There is evidence that many factors determine medication adherence, including adherence self-efficacy (confidence in one's ability to adhere) and relations with health care providers. However, there are no studies that examine how these two factors relate to each other and their subsequent influence on HIV medication adherence. The goal of the current analysis was to explore a model of medication adherence in which the relationship between positive provider interactions and adherence is mediated by adherence self-efficacy. Computerized self administered and interviewer administered self reported measures of medication adherence, demographic and treatment variables, provider interactions, and adherence self-efficacy were administered to 2765 HIV infected adults on ARV. Criteria for mediation were met, supporting a model in which adherence self-efficacy is the mechanism for the relationship between positive provider interactions and adherence. The finding was consistent when the sample was stratified by gender, race, injection drug use history, and whether the participant reported receipt of HIV specialty care. Positive provider interactions may foster greater adherence self-efficacy, which is associated with better adherence to medications. Results suggest implications for improving provider interactions in clinical care, and future directions for clarifying inter-relationships among provider interactions, adherence self-efficacy, and medication adherence are supported. PMID:16623624

The economic impact of improving phosphate binder therapy adherence and attainment of guideline phosphorus goals in hemodialysis patients: a Medicare cost-offset model.

PubMed

Ramakrishnan, Karthik; Braunhofer, Peter; Newsome, Britt; Lubeck, Deborah; Wang, Steven; Deuson, Jennifer; Claxton, Ami J

2014-12-01

Hyperphosphatemia (serum phosphorus >5.5 mg/dL) in hemodialysis patients is a key factor in mineral and bone disorders and is associated with increased hospitalization and mortality risks. Treatment with oral phosphate binders offers limited benefit in achieving target serum phosphorus concentrations due to high daily pill burden (7-10 pills/day) and associated poor medication adherence. The economic value of improving phosphate binder adherence and increasing percent time in range (PTR) for target phosphorus concentrations has not been previously assessed in dialysis patients. The current retrospective analysis was conducted to summarize health care cost savings to United States (US) payers associated with improved phosphate binder adherence and increased PTR for target phosphorus concentrations in adult end-stage renal disease (ESRD) patients receiving hemodialysis therapy. Phosphate binder adherence and PTR were derived from hemodialysis patients who were treated at a large dialysis organization between January 2007 and December 2011. Cost model inputs were derived from US Renal Data System data between July 2007 and December 2009. A cost-offset model was constructed to estimate monthly and annual incremental health care costs (total Medicare; inpatient, outpatient, and Medicare Part B) associated with different levels of phosphate binder adherence and PTR. Model inputs included number of ESRD patients, population adherence to phosphate binders, PTR associated with adherence to phosphate binders, and per-patient per-month cost associated with PTR. A base case model estimated monthly and annual costs of phosphate binder therapy in the population using estimated model inputs. The estimated adherence rate was used to determine number of patients in compliant and noncompliant groups. Monthly costs were calculated as the sum of per-patient per-month cost times the number of patients in adherent and nonadherent groups. Annual costs were monthly costs times 12 and assumed the same level of adherence, PTR, and per-patient per-month costs over time. To study the impact of improving phosphate binder adherence and PTR on cost outcomes, we hypothetically and simultaneously increased both base phosphate binders adherence and PTR for adherent patients (adherence/PTR: 10/20%, 20/40%, 30/60%). Monthly and annual costs were derived for each scenario and compared against the results of the base case model. One-way sensitivity analysis was performed to test model robustness. The base case model estimated total Medicare and inpatient costs of $5,152,342 and $1,435,644, respectively (N = 1,000). When base case model costs were compared to results of each extended model scenario, overall Medicare cost savings (range 0.3-1.9%) and inpatient cost savings (range 1.2-5.7%) were observed. The one-way sensitivity analysis indicated that results were sensitive to PTR for adherent and nonadherent patients and the factor used to increase adherence rate and PTR associated with adherence in the hypothetical scenarios. However, cost savings in overall Medicare costs and inpatient costs were still noted. Increasing phosphate binder adherence and improving phosphorus control were associated with increased cost savings in total Medicare costs and inpatient costs.

Assembly and analysis of eukaryotic Argonaute–RNA complexes in microRNA-target recognition

PubMed Central

Gan, Hin Hark; Gunsalus, Kristin C.

2015-01-01

Experimental studies have uncovered a variety of microRNA (miRNA)–target duplex structures that include perfect, imperfect and seedless duplexes. However, non-canonical binding modes from imperfect/seedless duplexes are not well predicted by computational approaches, which rely primarily on sequence and secondary structural features, nor have their tertiary structures been characterized because solved structures to date are limited to near perfect, straight duplexes in Argonautes (Agos). Here, we use structural modeling to examine the role of Ago dynamics in assembling viable eukaryotic miRNA-induced silencing complexes (miRISCs). We show that combinations of low-frequency, global modes of motion of Ago domains are required to accommodate RNA duplexes in model human and C. elegans Ago structures. Models of viable miRISCs imply that Ago adopts variable conformations at distinct target sites that generate distorted, imperfect miRNA-target duplexes. Ago's ability to accommodate a duplex is dependent on the region where structural distortions occur: distortions in solvent-exposed seed and 3′-end regions are less likely to produce steric clashes than those in the central duplex region. Energetic analyses of assembled miRISCs indicate that target recognition is also driven by favorable Ago-duplex interactions. Such structural insights into Ago loading and target recognition mechanisms may provide a more accurate assessment of miRNA function. PMID:26432829

Buckling Testing and Analysis of Honeycomb Sandwich Panel Arc Segments of a Full-Scale Fairing Barrel: Comparison of In- and Out-of-Autoclave Facesheet Configurations

NASA Technical Reports Server (NTRS)

Pineda, Evan Jorge; Myers, David E.; Kosareo, Daniel N.; Zalewski, Bart F.; Kellas, Sotiris; Dixon, Genevieve D.; Krivanek, Thomas M.; Gyekenyesi, Thomas G.

2014-01-01

Four honeycomb sandwich panels, representing 1/16th arc segments of a 10-m diameter barrel section of the Heavy Lift Launch Vehicle, were manufactured and tested under the NASA Composites for Exploration and the NASA Constellation Ares V programs. Two configurations were chosen for the panels: 6-ply facesheets with 1.125 in. honeycomb core and 8-ply facesheets with 1.0 in. honeycomb core. Additionally, two separate carbon fiber/epoxy material systems were chosen for the facesheets: in-autoclave IM7/977-3 and out-of-autoclave T40-800b/5320-1. Smaller 3 ft. by 5 ft. panels were cut from the 1/16th barrel sections and tested under compressive loading. Furthermore, linear eigenvalue and geometrically nonlinear finite element analyses were performed to predict the compressive response of each 3 ft. by 5 ft. panel. To improve the robustness of the geometrically nonlinear finite element model, measured surface imperfections were included in the geometry of the model. Both the linear and nonlinear models yielded good qualitative and quantitative predictions. Additionally, it was correctly predicted that the panel would fail in buckling prior to failing in strength. Furthermore, several imperfection studies were performed to investigate the influence of geometric imperfections, fiber angle misalignments, and three-dimensional effects on the compressive response of the panel.

Addressing drug adherence using an operations management model.

PubMed

Nunlee, Martin; Bones, Michelle

2014-01-01

OBJECTIVE To provide a model that enables health systems and pharmacy benefit managers to provide medications reliably and test for reliability and validity in the analysis of adherence to drug therapy of chronic disease. SUMMARY The quantifiable model described here can be used in conjunction with behavioral designs of drug adherence assessments. The model identifies variables that can be reproduced and expanded across the management of chronic diseases with drug therapy. By creating a reorder point system for reordering medications, the model uses a methodology commonly seen in operations research. The design includes a safety stock of medication and current supply of medication, which increases the likelihood that patients will have a continuous supply of medications, thereby positively affecting adherence by removing barriers. CONCLUSION This method identifies an adherence model that quantifies variables related to recommendations from health care providers; it can assist health care and service delivery systems in making decisions that influence adherence based on the expected order cycle days and the expected daily quantity of medication administered. This model addresses the possession of medication as a barrier to adherence.

Toward an information-motivation-behavioral skills model of microbicide adherence in clinical trials.

PubMed

Ferrer, Rebecca A; Morrow, Kathleen M; Fisher, William A; Fisher, Jeffrey D

2010-08-01

Unless optimal adherence in microbicide clinical trials is ensured, an efficacious microbicide may be rejected after trial completion, or development of a promising microbicide may be stopped, because low adherence rates create the illusion of poor efficacy. We provide a framework with which to conceptualize and improve microbicide adherence in clinical trials, supported by a critical review of the empirical literature. The information-motivation-behavioral skills (IMB) model of microbicide adherence conceptualizes microbicide adherence in clinical trials and highlights factors that can be addressed in behavioral interventions to increase adherence in such trials. This model asserts that microbicide adherence-related information, motivation, and behavioral skills are fundamental determinants of adherent microbicide utilization. Specifically, information consists of objective facts about microbicide use (e.g., administration and dosage) as well as heuristics that facilitate use (e.g., microbicides must be used with all partners). Motivation to adhere consists of attitudes toward personal use of microbicides (e.g., evaluating the consequences of using microbicides as good or pleasant) as well as social norms that support their use (e.g., beliefs that a sexual partner approves use of microbicides). Behavioral skills consist of objective skills necessary for microbicide adherence (e.g., the ability to apply the microbicide correctly and consistently). Empirical evidence concerning microbicide acceptability and adherence to spermicides, medication, and condom use regimens support the utility of this model for understanding and promoting microbicide adherence in clinical trials.

Accounting for imperfect detection in ecology: a quantitative review.

PubMed

Kellner, Kenneth F; Swihart, Robert K

2014-01-01

Detection in studies of species abundance and distribution is often imperfect. Assuming perfect detection introduces bias into estimation that can weaken inference upon which understanding and policy are based. Despite availability of numerous methods designed to address this assumption, many refereed papers in ecology fail to account for non-detection error. We conducted a quantitative literature review of 537 ecological articles to measure the degree to which studies of different taxa, at various scales, and over time have accounted for imperfect detection. Overall, just 23% of articles accounted for imperfect detection. The probability that an article incorporated imperfect detection increased with time and varied among taxa studied; studies of vertebrates were more likely to incorporate imperfect detection. Among articles that reported detection probability, 70% contained per-survey estimates of detection that were less than 0.5. For articles in which constancy of detection was tested, 86% reported significant variation. We hope that our findings prompt more ecologists to consider carefully the detection process when designing studies and analyzing results, especially for sub-disciplines where incorporation of imperfect detection in study design and analysis so far has been lacking.

Thermoelastic damping effect of the micro-ring resonator with irregular mass and stiffness

NASA Astrophysics Data System (ADS)

Kim, Jung-Hwan; Kim, Ji-Hwan

2016-05-01

Fundamentally, vibration characteristic is a main factor for the stability of structures. In this regard, the irregularity of mass and stiffness distributions for the structure have been an interesting issue for many years. Recently, the Micro Electro Mechanical Systems (MEMS) are developed for various applications such as gyro sensors. In the present work, in-plane vibration of micro-ring structure with multiple finite-sized imperfections is investigated. Then, the unbalance of the structure is represented using Heaviside Step Function for the inextensional modeling of the ring. Also, thermoelastic damping (TED) due to internal friction is studied based on Fourier's one-dimensional heat conduction equation using Laplace Transform. To obtain the quality-factors (Q-factors) for imperfect micro-ring, analytical solutions are calculated from governing equations of motion with TED. And then, the natural frequencies and the Q-factors are observed to separate into lower and higher modes. Additionally, the vibration mode shapes are presented, and the frequency trimming concept due to attached imperfections is investigated.

Efficient logistic regression designs under an imperfect population identifier.

PubMed

Albert, Paul S; Liu, Aiyi; Nansel, Tonja

2014-03-01

Motivated by actual study designs, this article considers efficient logistic regression designs where the population is identified with a binary test that is subject to diagnostic error. We consider the case where the imperfect test is obtained on all participants, while the gold standard test is measured on a small chosen subsample. Under maximum-likelihood estimation, we evaluate the optimal design in terms of sample selection as well as verification. We show that there may be substantial efficiency gains by choosing a small percentage of individuals who test negative on the imperfect test for inclusion in the sample (e.g., verifying 90% test-positive cases). We also show that a two-stage design may be a good practical alternative to a fixed design in some situations. Under optimal and nearly optimal designs, we compare maximum-likelihood and semi-parametric efficient estimators under correct and misspecified models with simulations. The methodology is illustrated with an analysis from a diabetes behavioral intervention trial. © 2013, The International Biometric Society.

INTEGRATION OF AN ECONOMY UNDER IMPERFECT COMPETITION WITH A TWELVE-CELL ECOLOGICAL MODEL

EPA Science Inventory

This report documents the scientific research work done to date on developing a generalized mathematical model depicting a combined economic-ecological-social system with the goal of making it available to the scientific community. The model is preliminary and has not been tested...

Parametric Study on the Response of Compression-Loaded Composite Shells With Geometric and Material Imperfections

NASA Technical Reports Server (NTRS)

Hilburger, Mark W.; Starnes, James H., Jr.

2004-01-01

The results of a parametric study of the effects of initial imperfections on the buckling and postbuckling response of three unstiffened thinwalled compression-loaded graphite-epoxy cylindrical shells with different orthotropic and quasi-isotropic shell-wall laminates are presented. The imperfections considered include initial geometric shell-wall midsurface imperfections, shell-wall thickness variations, local shell-wall ply-gaps associated with the fabrication process, shell-end geometric imperfections, nonuniform applied end loads, and variations in the boundary conditions including the effects of elastic boundary conditions. A high-fidelity nonlinear shell analysis procedure that accurately accounts for the effects of these imperfections on the nonlinear responses and buckling loads of the shells is described. The analysis procedure includes a nonlinear static analysis that predicts stable response characteristics of the shells and a nonlinear transient analysis that predicts unstable response characteristics.

Solution to the spectral filter problem of residual terrain modelling (RTM)

NASA Astrophysics Data System (ADS)

Rexer, Moritz; Hirt, Christian; Bucha, Blažej; Holmes, Simon

2018-06-01

In physical geodesy, the residual terrain modelling (RTM) technique is frequently used for high-frequency gravity forward modelling. In the RTM technique, a detailed elevation model is high-pass-filtered in the topography domain, which is not equivalent to filtering in the gravity domain. This in-equivalence, denoted as spectral filter problem of the RTM technique, gives rise to two imperfections (errors). The first imperfection is unwanted low-frequency (LF) gravity signals, and the second imperfection is missing high-frequency (HF) signals in the forward-modelled RTM gravity signal. This paper presents new solutions to the RTM spectral filter problem. Our solutions are based on explicit modelling of the two imperfections via corrections. The HF correction is computed using spectral domain gravity forward modelling that delivers the HF gravity signal generated by the long-wavelength RTM reference topography. The LF correction is obtained from pre-computed global RTM gravity grids that are low-pass-filtered using surface or solid spherical harmonics. A numerical case study reveals maximum absolute signal strengths of ˜ 44 mGal (0.5 mGal RMS) for the HF correction and ˜ 33 mGal (0.6 mGal RMS) for the LF correction w.r.t. a degree-2160 reference topography within the data coverage of the SRTM topography model (56°S ≤ φ ≤ 60°N). Application of the LF and HF corrections to pre-computed global gravity models (here the GGMplus gravity maps) demonstrates the efficiency of the new corrections over topographically rugged terrain. Over Switzerland, consideration of the HF and LF corrections reduced the RMS of the residuals between GGMplus and ground-truth gravity from 4.41 to 3.27 mGal, which translates into ˜ 26% improvement. Over a second test area (Canada), our corrections reduced the RMS of the residuals between GGMplus and ground-truth gravity from 5.65 to 5.30 mGal (˜ 6% improvement). Particularly over Switzerland, geophysical signals (associated, e.g. with valley fillings) were found to stand out more clearly in the RTM-reduced gravity measurements when the HF and LF correction are taken into account. In summary, the new RTM filter corrections can be easily computed and applied to improve the spectral filter characteristics of the popular RTM approach. Benefits are expected, e.g. in the context of the development of future ultra-high-resolution global gravity models, smoothing of observed gravity data in mountainous terrain and geophysical interpretations of RTM-reduced gravity measurements.

Micromechanical Modeling of Woven Metal Matrix Composites

NASA Technical Reports Server (NTRS)

Bednarcyk, Brett A.; Pindera, Marek-Jerzy

1997-01-01

This report presents the results of an extensive micromechanical modeling effort for woven metal matrix composites. The model is employed to predict the mechanical response of 8-harness (8H) satin weave carbon/copper (C/Cu) composites. Experimental mechanical results for this novel high thermal conductivity material were recently reported by Bednarcyk et al. along with preliminary model results. The micromechanics model developed herein is based on an embedded approach. A micromechanics model for the local (micro-scale) behavior of the woven composite, the original method of cells (Aboudi), is embedded in a global (macro-scale) micromechanics model (the three-dimensional generalized method of cells (GMC-3D) (Aboudi). This approach allows representation of true repeating unit cells for woven metal matrix composites via GMC-3D, and representation of local effects, such as matrix plasticity, yarn porosity, and imperfect fiber-matrix bonding. In addition, the equations of GMC-3D were reformulated to significantly reduce the number of unknown quantities that characterize the deformation fields at the microlevel in order to make possible the analysis of actual microstructures of woven composites. The resulting micromechanical model (WCGMC) provides an intermediate level of geometric representation, versatility, and computational efficiency with respect to previous analytical and numerical models for woven composites, but surpasses all previous modeling work by allowing the mechanical response of a woven metal matrix composite, with an elastoplastic matrix, to be examined for the first time. WCGMC is employed to examine the effects of composite microstructure, porosity, residual stresses, and imperfect fiber-matrix bonding on the predicted mechanical response of 8H satin C/Cu. The previously reported experimental results are summarized, and the model predictions are compared to monotonic and cyclic tensile and shear test data. By considering appropriate levels of porosity, residual stresses, and imperfect fiber-matrix debonding, reasonably good qualitative and quantitative correlation is achieved between model and experiment.

Empirical Validation of the Information–Motivation–Behavioral Skills Model of Diabetes Medication Adherence: A Framework for Intervention

PubMed Central

Mayberry, Lindsay S.; Osborn, Chandra Y.

2014-01-01

OBJECTIVE Suboptimal adherence to diabetes medications is prevalent and associated with unfavorable health outcomes, but it remains unclear what intervention content is necessary to effectively promote medication adherence in diabetes. In other disease contexts, the Information–Motivation–Behavioral skills (IMB) model has effectively explained and promoted medication adherence and thus may have utility in explaining and promoting adherence to diabetes medications. We tested the IMB model’s hypotheses in a sample of adults with type 2 diabetes. RESEARCH DESIGN AND METHODS Participants (N = 314) completed an interviewer-administered survey and A1C test. Structural equation models tested the effects of diabetes medication adherence-related information, motivation, and behavioral skills on medication adherence and the effect of medication adherence on A1C. RESULTS The IMB elements explained 41% of the variance in adherence, and adherence explained 9% of the variance in A1C. As predicted, behavioral skills had a direct effect on adherence (β = 0.59; P < 0.001) and mediated the effects of information (indirect effect 0.08 [0.01–0.15]) and motivation (indirect effect 0.12 [0.05–0.20]) on adherence. Medication adherence significantly predicted glycemic control (β = −0.30; P < 0.001). Neither insulin status nor regimen complexity was associated with adherence, and neither moderated associations between the IMB constructs and adherence. CONCLUSIONS The results support the IMB model’s predictions and identify modifiable and intervenable determinants of diabetes medication adherence. Medication adherence promotion interventions may benefit from content targeting patients’ medication adherence-related information, motivation, and behavioral skills and assessing the degree to which change in these determinants leads to changes in medication adherence behavior. PMID:24598245

Positive psychological determinants of treatment adherence among primary care patients.

PubMed

Nsamenang, Sheri A; Hirsch, Jameson K

2015-07-01

Patient adherence to medical treatment recommendations can affect disease prognosis, and may be beneficially or deleteriously influenced by psychological factors. Aim We examined the relationships between both adaptive and maladaptive psychological factors and treatment adherence among a sample of primary care patients. One hundred and one rural, primary care patients completed the Life Orientation Test-Revised, Trait Hope Scale, Future Orientation Scale, NEO-FFI Personality Inventory (measuring positive and negative affect), and Medical Outcomes Study General Adherence Scale. In independent models, positive affect, optimism, hope, and future orientation were beneficially associated with treatment adherence, whereas pessimism and negative affect were negatively related to adherence. In multivariate models, only negative affect, optimism and hope remained significant and, in a comparative model, trait hope was most robustly associated with treatment adherence. Therapeutically, addressing negative emotions and expectancies, while simultaneously bolstering motivational and goal-directed attributes, may improve adherence to treatment regimens.

Hierarchical models of animal abundance and occurrence

USGS Publications Warehouse

Royle, J. Andrew; Dorazio, R.M.

2006-01-01

Much of animal ecology is devoted to studies of abundance and occurrence of species, based on surveys of spatially referenced sample units. These surveys frequently yield sparse counts that are contaminated by imperfect detection, making direct inference about abundance or occurrence based on observational data infeasible. This article describes a flexible hierarchical modeling framework for estimation and inference about animal abundance and occurrence from survey data that are subject to imperfect detection. Within this framework, we specify models of abundance and detectability of animals at the level of the local populations defined by the sample units. Information at the level of the local population is aggregated by specifying models that describe variation in abundance and detection among sites. We describe likelihood-based and Bayesian methods for estimation and inference under the resulting hierarchical model. We provide two examples of the application of hierarchical models to animal survey data, the first based on removal counts of stream fish and the second based on avian quadrat counts. For both examples, we provide a Bayesian analysis of the models using the software WinBUGS.

Innovative approach to the design and evaluation of treatment adherence interventions for drug-resistant TB.

PubMed

Alegria-Flores, K; Weiner, B J; Wiesen, C A; Lich, K L H; Van Rie, A; Paul, J E; Tovar, M A

2017-11-01

Drug-resistant tuberculosis (DR-TB) treatment is expensive, lengthy, and can cause severe side effects. Patients face socio-economic, psychosocial, and systemic barriers to adherence; poor adherence results in poor treatment outcomes. To estimate the effects of the components of the information-motivation-behavioral skills model on DR-TB treatment adherence. We recruited 326 adults receiving DR-TB treatment and 86 of their health care service providers from 40 health centers in Lima, Peru. The main outcome was adherence (i.e., the proportion of prescribed doses taken by a patient). Exposure measures were adherence information, motivation, and behavioral skills; loss to follow-up during previous TB treatment(s); providers' work engagement; and patient-perceived support from his/her social network. Structural equation modeling revealed that adherence information and motivation had positive effects on adherence, but only if mediated through behavioral skills (β = 0.02, P < 0.01 and β = 0.07, P < 0.001, respectively). Behavioral skills had a direct positive effect on adherence (β = 0.27, P < 0.001). Loss to follow-up during previous treatment had a direct negative effect, providers' work engagement had a direct positive effect, and perceived support had indirect positive effects on adherence. The model's overall R2 was 0.76. The components of the information-motivation-behavioral skills model were associated with adherence and could be used to design, monitor, and evaluate interventions targeting adherence to DR-TB treatment.

Theoretical Approaches to Enhancing Motivation for Adherence to Antidepressant Medications.

PubMed

Hamrin, Vanya; Sinclair, Vaughn G; Gardner, Virginia

2017-04-01

Adherence to antidepressants is a major challenge in our health care system, with a high percentage of patients discontinuing their medications within six months. The purpose of this position paper is to discuss theoretical frameworks that address the psychological beliefs, benefits and barriers and feelings of autonomy that affect a person's willingness and motivation to take anti-depressant medications within a therapeutic relationship with a nurse practitioner. Three theoretical frameworks were selected to highlight particular perspectives relevant to enhancing patient motivation for medication adherence. The Self-Regulation Model, Health Belief Model, and Self-Determination Theory combined with motivational interviewing all offer guidance on strategies for improving adherence to antidepressants. The Self-Regulation Model underscores the importance of illness representations that prompt considering patient perceptions of depression that affect adherence. The Health Belief Model focuses on cost-benefit considerations that affect patient's adherence, along with perceived control. Finally, Self-Determination Theory combined with motivational interviewing offers strategies that enhance autonomy and optimize collaboration and motivation for adherence. These three theoretical models are applied to a vignette for a patient who is having difficulty with adherence to antidepressant medication. Copyright © 2016 Elsevier Inc. All rights reserved.

Adherence of coagulase-negative staphylococci to plastic tissue culture plates: a quantitative model for the adherence of staphylococci to medical devices.

PubMed Central

Christensen, G D; Simpson, W A; Younger, J J; Baddour, L M; Barrett, F F; Melton, D M; Beachey, E H

1985-01-01

The adherence of coagulase-negative staphylococci to smooth surfaces was assayed by measuring the optical densities of stained bacterial films adherent to the floors of plastic tissue culture plates. The optical densities correlated with the weight of the adherent bacterial film (r = 0.906; P less than 0.01). The measurements also agreed with visual assessments of bacterial adherence to culture tubes, microtiter plates, and tissue culture plates. Selected clinical strains were passed through a mouse model for foreign body infections and a rat model for catheter-induced endocarditis. The adherence measurements of animal passed strains remained the same as those of the laboratory-maintained parent strain. Spectrophotometric classification of coagulase-negative staphylococci into nonadherent and adherent categories according to these measurements had a sensitivity, specificity, and accuracy of 90.6, 80.8, and 88.4%, respectively. We examined a previously described collection of 127 strains of coagulase-negative staphylococci isolated from an outbreak of intravascular catheter-associated sepsis; strains associated with sepsis were more adherent than blood culture contaminants and cutaneous strains (P less than 0.001). We also examined a collection of 84 strains isolated from pediatric patients with cerebrospinal fluid (CSF) shunts; once again, pathogenic strains were more adherent than were CSF contaminants (P less than 0.01). Finally, we measured the adherence of seven endocarditis strains. As opposed to strains associated with intravascular catheters and CSF shunts, endocarditis strains were less adherent than were saprophytic strains of coagulase-negative staphylococci. The optical densities of bacterial films adherent to plastic tissue culture plates serve as a quantitative model for the study of the adherence of coagulase-negative staphylococci to medical devices, a process which may be important in the pathogenesis of foreign body infections. Images PMID:3905855

Coordinating vendor-buyer decisions for imperfect quality items considering trade credit and fully backlogged shortages

NASA Astrophysics Data System (ADS)

Khanna, Aditi; Gautam, Prerna; Jaggi, Chandra K.

2016-03-01

Supply chain management has become a critical issue for modern business environments. In today's world of cooperative decision-making, individual decisions in order to reduce inventory costs may not lead to an overall optimal solution. Coordination is necessary among participants of supply chain to achieve better performance. There are legitimate and important efforts from the vendor to enhance the relation with buyer; one such effort is offering trade credit which has been a driver of growth and development of business between them. The cost of financing is a core consideration in effective financial management, in general and in context of business. Also, due to imperfect production a vendor may produce defective items which results in shortages. Motivated with these aspects, an integrated vendor-buyer inventory model is developed for imperfect quality items with allowable shortages; in which the vendor offers credit period to the buyer for payment. The objective is to minimize the total joint annual costs incurred by the vendor and the buyer by using integrated decision making approach. The expected total annual integrated cost is derived and a solution procedure is provided to find the optimal solution. Numerical analysis shows that the integrated model gives an impressive cost reduction, in comparison to independent decision policies by the vendor and the buyer.

Optical truss and retroreflector modeling for picometer laser metrology

NASA Astrophysics Data System (ADS)

Hines, Braden E.

1993-09-01

Space-based astrometric interferometer concepts typically have a requirement for the measurement of the internal dimensions of the instrument to accuracies in the picometer range. While this level of resolution has already been achieved for certain special types of laser gauges, techniques for picometer-level accuracy need to be developed to enable all the various kinds of laser gauges needed for space-based interferometers. Systematic errors due to retroreflector imperfections become important as soon as the retroreflector is allowed to either translate in position or articulate in angle away from its nominal zero-point. Also, when combining several laser interferometers to form a three-dimensional laser gauge (a laser optical truss), systematic errors due to imperfect knowledge of the truss geometry are important as the retroreflector translates away from its nominal zero-point. In order to assess the astrometric performance of a proposed instrument, it is necessary to determine how the effects of an imperfect laser metrology system impact the astrometric accuracy. This paper show the development of an error propagation model from errors in the 1-D metrology measurements through the impact on the overall astrometric accuracy for OSI. Simulations are then presented based on this development which were used to define a multiplier which determines the 1-D metrology accuracy required to produce a given amount of fringe position error.

Adherence to oral anticoagulants in patients with atrial fibrillation-a population-based retrospective cohort study linking health information systems in the Valencia region, Spain: a study protocol.

PubMed

Sanfélix-Gimeno, G; Rodríguez-Bernal, C L; Hurtado, I; Baixáuli-Pérez, C; Librero, J; Peiró, S

2015-10-19

Adherence to oral anticoagulation (OAC) treatment, vitamin K antagonists or new oral anticoagulants, is an essential element for effectiveness. Information on adherence to OAC in atrial fibrillation (AF) and the impact of adherence on clinical outcomes using real-world data barely exists. We aim to describe the patterns of adherence to OAC over time in patients with AF, estimate the associated factors and their impact on clinical events, and assess the same issues with conventional measures of primary and secondary adherence-proportion of days covered (PDC) and persistence-in routine clinical practice. This is a population-based retrospective cohort study including all patients with AF treated with OAC from 2010 to date in Valencia, Spain; data will be obtained from diverse electronic records of the Valencia Health Agency. adherence trajectories. (1) primary non-adherence; (2) secondary adherence: (a) PDC, (b) persistence. Clinical outcomes: hospitalisation for haemorrhagic or thromboembolic events and death during follow-up. (1) description of baseline characteristics, adherence patterns (trajectory models or latent class growth analysis models) and conventional adherence measures; (2) logistic or Cox multivariate regression models, to assess the associations between adherence measures and the covariates, and logistic multinomial regression models, to identify characteristics associated with each trajectory; (3) Cox proportional hazard models, to assess the relationship between adherence and clinical outcomes, with propensity score adjustment applied to further control for potential confounders; (4) to estimate the importance of different healthcare levels in the variations of adherence, logistic or Cox multilevel regression models. This study has been approved by the corresponding Clinical Research Ethics Committee. We plan to disseminate the project's findings through peer-reviewed publications and presentations at relevant health conferences. Policy reports will also be prepared in order to promote the translation of our findings into policy and clinical practice. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

INTEGRATION OF AN ECONOMIC WITH AN ECOLOGICAL MODEL

EPA Science Inventory

We summarize our work on integration of an economy under imperfect competition with a simple Lotka-Volterra type ecological model. Firms and households operate within a single period planning horizon, thus there is no savings or investment. Wages are set by a dominant employer. P...

Improvement of the F-Perceptory Approach Through Management of Fuzzy Complex Geographic Objects

NASA Astrophysics Data System (ADS)

Khalfi, B.; de Runz, C.; Faiz, S.; Akdag, H.

2015-08-01

In the real world, data is imperfect and in various ways such as imprecision, vagueness, uncertainty, ambiguity and inconsistency. For geographic data, the fuzzy aspect is mainly manifested in time, space and the function of objects and is due to a lack of precision. Therefore, the researchers in the domain emphasize the importance of modeling data structures in GIS but also their lack of adaptation to fuzzy data. The F-Perceptory approachh manages the modeling of imperfect geographic information with UML. This management is essential to maintain faithfulness to reality and to better guide the user in his decision-making. However, this approach does not manage fuzzy complex geographic objects. The latter presents a multiple object with similar or different geographic shapes. So, in this paper, we propose to improve the F-Perceptory approach by proposing to handle fuzzy complex geographic objects modeling. In a second step, we propose its transformation to the UML modeling.

Aspectual asymmetries in the mental representation of events: Role of lexical and grammatical aspect.

PubMed

Yap, Foong Ha; Chu, Patrick Chun Kau; Yiu, Emily Sze Man; Wong, Stella Fay; Kwan, Stella Wing Man; Matthews, Stephen; Tan, Li Hai; Li, Ping; Shirai, Yasuhiro

2009-07-01

Temporal information is important in the construction of situation models, and many languages make use of perfective and imperfective aspect markers to distinguish between completed situations (e.g., He made a cake) and ongoing situations (e.g., He is making a cake). Previous studies in which the effect of grammatical aspect has been examined have shown that perfective sentences are often processed more quickly than imperfective ones (e.g., Chan, Yap, Shirai, & Matthews, 2004; Madden & Zwaan, 2003; Yap et al., 2004; Yap et al., 2006). However, these studies used only accomplishment verbs (i.e., verbs with an inherent endpoint, such as bake a cake). The present study on the processing of Cantonese includes activity verbs (i.e., durative verbs with no inherent endpoint, such as play the piano), and the results indicate a strong interaction between lexical aspect (i.e., verb type) and grammatical aspect. That is, perfective sentences were processed more quickly with accomplishment verbs, consistent with previous findings, but imperfective sentences were processed more quickly with activity verbs. We suggest that these different aspectual asymmetries emerge as a result of the inherent associations between accomplishment verbs and the bounded features of perfective aspect and between activity verbs and the unbounded features of imperfective aspect. The sentence stimuli from this study may be downloaded from mc.psychonomic-journals.org/content/supplemental.

Imperfect information facilitates the evolution of reciprocity.

PubMed

Kurokawa, Shun

2016-06-01

The existence of cooperation demands explanation since cooperation is costly to the actor. Reciprocity has long been regarded as a potential explanatory mechanism for the existence of cooperation. Reciprocity is a mechanism wherein a cooperator responds to an opponent's behavior by switching his/her own behavior. Hence, a possible problematic case relevant to the theory of reciprocity evolution arises when the mechanism is such that the information regarding an opponent's behavior is imperfect. Although it has been confirmed also by previous theoretical studies that imperfect information interferes with the evolution of reciprocity, this argument is based on the assumption that there are no mistakes in behavior. And, a previous study presumed that it might be expected that when such mistakes occur, reciprocity can more readily evolve in the case of imperfect information than in the case of perfect information. The reason why the previous study considers so is that in the former case, reciprocators can miss defections incurred by other reciprocators' mistakes due to imperfect information, allowing cooperation to persist when such reciprocators meet. However, contrary to this expectation, the previous study has shown that even when mistakes occur, imperfect information interferes with the evolution of reciprocity. Nevertheless, the previous study assumed that payoffs are linear (i.e., that the effect of behavior is additive and there are no synergetic effects). In this study, we revisited the same problem but removed the assumption that payoffs are linear. We used evolutionarily stable strategy analysis to compare the condition for reciprocity to evolve when mistakes occur and information is imperfect with the condition for reciprocity to evolve when mistakes occur and information is perfect. Our study revealed that when payoffs are not linear, imperfect information can facilitate the evolution of reciprocity when mistakes occur; while when payoffs are linear, imperfect information disturbs the evolution of reciprocity even when mistakes occur. Imperfect information can encourage the evolution of cooperation. Copyright © 2016 Elsevier Inc. All rights reserved.

Modeling species occurrence dynamics with multiple states and imperfect detection

USGS Publications Warehouse

MacKenzie, D.I.; Nichols, J.D.; Seamans, M.E.; Gutierrez, R.J.

2009-01-01

Recent extensions of occupancy modeling have focused not only on the distribution of species over space, but also on additional state variables (e.g., reproducing or not, with or without disease organisms, relative abundance categories) that provide extra information about occupied sites. These biologist-driven extensions are characterized by ambiguity in both species presence and correct state classification, caused by imperfect detection. We first show the relationships between independently published approaches to the modeling of multistate occupancy. We then extend the pattern-based modeling to the case of sampling over multiple seasons or years in order to estimate state transition probabilities associated with system dynamics. The methodology and its potential for addressing relevant ecological questions are demonstrated using both maximum likelihood (occupancy and successful reproduction dynamics of California Spotted Owl) and Markov chain Monte Carlo estimation approaches (changes in relative abundance of green frogs in Maryland). Just as multistate capture-recapture modeling has revolutionized the study of individual marked animals, we believe that multistate occupancy modeling will dramatically increase our ability to address interesting questions about ecological processes underlying population-level dynamics. ?? 2009 by the Ecological Society of America.

A hidden-process model for estimating prespawn mortality using carcass survey data

USGS Publications Warehouse

DeWeber, J. Tyrell; Peterson, James T.; Sharpe, Cameron; Kent, Michael L.; Colvin, Michael E.; Schreck, Carl B.

2017-01-01

After returning to spawning areas, adult Pacific salmon Oncorhynchus spp. often die without spawning successfully, which is commonly referred to as prespawn mortality. Prespawn mortality reduces reproductive success and can thereby hamper conservation, restoration, and reintroduction efforts. The primary source of information used to estimate prespawn mortality is collected through carcass surveys, but estimation can be difficult with these data due to imperfect detection and carcasses with unknown spawning status. To facilitate unbiased estimation of prespawn mortality and associated uncertainty, we developed a hidden-process mark–recovery model to estimate prespawn mortality rates from carcass survey data while accounting for imperfect detection and unknown spawning success. We then used the model to estimate prespawn mortality and identify potential associated factors for 3,352 adult spring Chinook Salmon O. tshawytscha that were transported above Foster Dam on the South Santiam River (Willamette River basin, Oregon) from 2009 to 2013. Estimated prespawn mortality was relatively low (≤13%) in most years (interannual mean = 28%) but was especially high (74%) in 2013. Variation in prespawn mortality estimates among outplanted groups of fish within each year was also very high, and some of this variation was explained by a trend toward lower prespawn mortality among fish that were outplanted later in the year. Numerous efforts are being made to monitor and, when possible, minimize prespawn mortality in salmon populations; this model can be used to provide unbiased estimates of spawning success that account for unknown fate and imperfect detection, which are common to carcass survey data.

Effect of Material Thermo-viscoplastic Modeling on the Prediction of Forming Limit Curves of Aluminum Alloy 5086

NASA Astrophysics Data System (ADS)

Chu, Xingrong; Leotoing, Lionel; Guines, Dominique; Ragneau, Eric

2015-09-01

A solution to improve the formability of aluminum alloy sheets can consist in investigating warm forming processes. The optimization of forming process parameters needs a precise evaluation of material properties and sheet metal formability for actual operating environment. Based on the analytical M-K theory, a finite element (FE) M-K model was proposed to predict forming limit curves (FLCs) at different temperatures and strain rates. The influences of initial imperfection value ( f 0) and material thermos-viscoplastic model on the FLCs are discussed in this work. The flow stresses of AA5086 were characterized by uniaxial tensile tests at different temperatures (20, 150, and 200 °C) and equivalent strain rates (0.0125, 0.125, and 1.25 s-1). Three types of hardening models (power law model, saturation model, and mixed model) were proposed and adapted to correlate the experimental flow stresses. The three hardening models were implemented into the FE M-K model in order to predict FLCs for different forming conditions. The predicted limit strains are very sensitive to the thermo-viscoplastic modeling of AA5086 and to the calibration of the initial geometrical imperfection which controls the onset of necking.

Validation of individual and aggregate global flood hazard models for two major floods in Africa.

NASA Astrophysics Data System (ADS)

Trigg, M.; Bernhofen, M.; Whyman, C.

2017-12-01

A recent intercomparison of global flood hazard models undertaken by the Global Flood Partnership shows that there is an urgent requirement to undertake more validation of the models against flood observations. As part of the intercomparison, the aggregated model dataset resulting from the project was provided as open access data. We compare the individual and aggregated flood extent output from the six global models and test these against two major floods in the African Continent within the last decade, namely severe flooding on the Niger River in Nigeria in 2012, and on the Zambezi River in Mozambique in 2007. We test if aggregating different number and combination of models increases model fit to the observations compared with the individual model outputs. We present results that illustrate some of the challenges of comparing imperfect models with imperfect observations and also that of defining the probability of a real event in order to test standard model output probabilities. Finally, we propose a collective set of open access validation flood events, with associated observational data and descriptions that provide a standard set of tests across different climates and hydraulic conditions.

Interplay between cost and benefits triggers nontrivial vaccination uptake

NASA Astrophysics Data System (ADS)

Steinegger, Benjamin; Cardillo, Alessio; Rios, Paolo De Los; Gómez-Gardeñes, Jesús; Arenas, Alex

2018-03-01

The containment of epidemic spreading is a major challenge in science. Vaccination, whenever available, is the best way to prevent the spreading, because it eventually immunizes individuals. However, vaccines are not perfect, and total immunization is not guaranteed. Imperfect immunization has driven the emergence of antivaccine movements that totally alter the predictions about the epidemic incidence. Here, we propose a mathematically solvable mean-field vaccination model to mimic the spontaneous adoption of vaccines against influenzalike diseases and the expected epidemic incidence. The results are in agreement with extensive Monte Carlo simulations of the epidemics and vaccination coevolutionary processes. Interestingly, the results reveal a nonmonotonic behavior on the vaccination coverage that increases with the imperfection of the vaccine and after decreases. This apparent counterintuitive behavior is analyzed and understood from stability principles of the proposed mathematical model.

Modeling and additive manufacturing of bio-inspired composites with tunable fracture mechanical properties.

PubMed

Dimas, Leon S; Buehler, Markus J

2014-07-07

Flaws, imperfections and cracks are ubiquitous in material systems and are commonly the catalysts of catastrophic material failure. As stresses and strains tend to concentrate around cracks and imperfections, structures tend to fail far before large regions of material have ever been subjected to significant loading. Therefore, a major challenge in material design is to engineer systems that perform on par with pristine structures despite the presence of imperfections. In this work we integrate knowledge of biological systems with computational modeling and state of the art additive manufacturing to synthesize advanced composites with tunable fracture mechanical properties. Supported by extensive mesoscale computer simulations, we demonstrate the design and manufacturing of composites that exhibit deformation mechanisms characteristic of pristine systems, featuring flaw-tolerant properties. We analyze the results by directly comparing strain fields for the synthesized composites, obtained through digital image correlation (DIC), and the computationally tested composites. Moreover, we plot Ashby diagrams for the range of simulated and experimental composites. Our findings show good agreement between simulation and experiment, confirming that the proposed mechanisms have a significant potential for vastly improving the fracture response of composite materials. We elucidate the role of stiffness ratio variations of composite constituents as an important feature in determining the composite properties. Moreover, our work validates the predictive ability of our models, presenting them as useful tools for guiding further material design. This work enables the tailored design and manufacturing of composites assembled from inferior building blocks, that obtain optimal combinations of stiffness and toughness.

Group‐Based Trajectory Models: Assessing Adherence to Antihypertensive Medication in Older Adults in a Community Pharmacy Setting

PubMed Central

Stewart, Derek; Smith, Susan M.; Gallagher, Paul; Cousins, Gráinne

2017-01-01

Antihypertensive medication nonadherence is highly prevalent, leading to uncontrolled blood pressure. Methods that facilitate the targeting and tailoring of adherence interventions in clinical settings are required. Group‐Based Trajectory Modeling (GBTM) is a newer method to evaluate adherence using pharmacy dispensing (refill) data that has advantages over traditional refill adherence metrics (e.g. Proportion of Days Covered) by identifying groups of patients who may benefit from adherence interventions, and identifying patterns of adherence behavior over time that may facilitate tailoring of an adherence intervention. We evaluated adherence to antihypertensive medication in 905 patients over a 12‐month period in a community pharmacy setting using GBTM, identifying three subgroups of adherence patterns: 52.8%, 40.7%, and 6.5% had very high, high, and low adherence, respectively. However, GBTM failed to demonstrate predictive validity with blood pressure at 12 months. Further research on the validity of adherence measures that facilitate interventions in clinical settings is required. PMID:28875569

Implementation ambiguity: The fifth element long lost in uncertainty budgets for land biogeochemical modeling

NASA Astrophysics Data System (ADS)

Tang, J.; Riley, W. J.

2015-12-01

Previous studies have identified four major sources of predictive uncertainty in modeling land biogeochemical (BGC) processes: (1) imperfect initial conditions (e.g., assumption of preindustrial equilibrium); (2) imperfect boundary conditions (e.g., climate forcing data); (3) parameterization (type I equifinality); and (4) model structure (type II equifinality). As if that were not enough to cause substantial sleep loss in modelers, we propose here a fifth element of uncertainty that results from implementation ambiguity that occurs when the model's mathematical description is translated into computational code. We demonstrate the implementation ambiguity using the example of nitrogen down regulation, a necessary process in modeling carbon-climate feedbacks. We show that, depending on common land BGC model interpretations of the governing equations for mineral nitrogen, there are three different implementations of nitrogen down regulation. We coded these three implementations in the ACME land model (ALM), and explored how they lead to different preindustrial and contemporary land biogeochemical states and fluxes. We also show how this implementation ambiguity can lead to different carbon-climate feedback estimates across the RCP scenarios. We conclude by suggesting how to avoid such implementation ambiguity in ESM BGC models.

An open-population hierarchical distance sampling model

USGS Publications Warehouse

Sollmann, Rachel; Beth Gardner,; Richard B Chandler,; Royle, J. Andrew; T Scott Sillett,

2015-01-01

Modeling population dynamics while accounting for imperfect detection is essential to monitoring programs. Distance sampling allows estimating population size while accounting for imperfect detection, but existing methods do not allow for direct estimation of demographic parameters. We develop a model that uses temporal correlation in abundance arising from underlying population dynamics to estimate demographic parameters from repeated distance sampling surveys. Using a simulation study motivated by designing a monitoring program for island scrub-jays (Aphelocoma insularis), we investigated the power of this model to detect population trends. We generated temporally autocorrelated abundance and distance sampling data over six surveys, using population rates of change of 0.95 and 0.90. We fit the data generating Markovian model and a mis-specified model with a log-linear time effect on abundance, and derived post hoc trend estimates from a model estimating abundance for each survey separately. We performed these analyses for varying number of survey points. Power to detect population changes was consistently greater under the Markov model than under the alternatives, particularly for reduced numbers of survey points. The model can readily be extended to more complex demographic processes than considered in our simulations. This novel framework can be widely adopted for wildlife population monitoring.

An open-population hierarchical distance sampling model.

PubMed

Sollmann, Rahel; Gardner, Beth; Chandler, Richard B; Royle, J Andrew; Sillett, T Scott

2015-02-01

Modeling population dynamics while accounting for imperfect detection is essential to monitoring programs. Distance sampling allows estimating population size while accounting for imperfect detection, but existing methods do not allow for estimation of demographic parameters. We develop a model that uses temporal correlation in abundance arising from underlying population dynamics to estimate demographic parameters from repeated distance sampling surveys. Using a simulation study motivated by designing a monitoring program for Island Scrub-Jays (Aphelocoma insularis), we investigated the power of this model to detect population trends. We generated temporally autocorrelated abundance and distance sampling data over six surveys, using population rates of change of 0.95 and 0.90. We fit the data generating Markovian model and a mis-specified model with a log-linear time effect on abundance, and derived post hoc trend estimates from a model estimating abundance for each survey separately. We performed these analyses for varying numbers of survey points. Power to detect population changes was consistently greater under the Markov model than under the alternatives, particularly for reduced numbers of survey points. The model can readily be extended to more complex demographic processes than considered in our simulations. This novel framework can be widely adopted for wildlife population monitoring.

Standardizing terminology and definitions of medication adherence and persistence in research employing electronic databases.

PubMed

Raebel, Marsha A; Schmittdiel, Julie; Karter, Andrew J; Konieczny, Jennifer L; Steiner, John F

2013-08-01

To propose a unifying set of definitions for prescription adherence research utilizing electronic health record prescribing databases, prescription dispensing databases, and pharmacy claims databases and to provide a conceptual framework to operationalize these definitions consistently across studies. We reviewed recent literature to identify definitions in electronic database studies of prescription-filling patterns for chronic oral medications. We then develop a conceptual model and propose standardized terminology and definitions to describe prescription-filling behavior from electronic databases. The conceptual model we propose defines 2 separate constructs: medication adherence and persistence. We define primary and secondary adherence as distinct subtypes of adherence. Metrics for estimating secondary adherence are discussed and critiqued, including a newer metric (New Prescription Medication Gap measure) that enables estimation of both primary and secondary adherence. Terminology currently used in prescription adherence research employing electronic databases lacks consistency. We propose a clear, consistent, broadly applicable conceptual model and terminology for such studies. The model and definitions facilitate research utilizing electronic medication prescribing, dispensing, and/or claims databases and encompasses the entire continuum of prescription-filling behavior. Employing conceptually clear and consistent terminology to define medication adherence and persistence will facilitate future comparative effectiveness research and meta-analytic studies that utilize electronic prescription and dispensing records.

Patient-Reported Disease-Modifying Therapy Adherence in the Clinic: A Reliable Metric?

PubMed

Conway, Devon S; Cecilia Vieira, Maria; Thompson, Nicolas R; Parker, Kaila N; Meng, Xiangyi; Fox, Robert J

2018-01-01

Adherence to multiple sclerosis (MS) disease-modifying therapy (DMT) is commonly assessed through patient reporting, but patient-reported adherence is rarely studied. To determine rates of DMT adherence reported from patient to clinician, reasons for nonadherence, and relationships between adherence and outcomes. We identified relapsing-remitting MS patients on DMT for ≥3 months. DMT adherence was defined as taking ≥80% of doses. Linear and logistic regression models were created used to determine the association of baseline adherence with several patient reported outcomes and the timed 25-foot walk at 6 months, 1 year, 2 years, and 3 years after the index visit. The analysis included 1148 patients, of whom 501 had data at 6 months, 544 at 1 year, 331 at 2 years, and 247 at 3 years. Baseline adherence was 94.9% and overall adherence was 93.1%. Forgetting was the most common reason for missed doses. In the adjusted models, adherence was not associated with the outcomes. Higher than expected adherence and a lack of association between adherence and outcomes suggests patient reported adherence may not be reliable. Further research is needed to clarify the relationship between patient-reported adherence and relapses or new lesion formation.

Longitudinal antiretroviral adherence in HIV+ Ugandan parents and their children initiating HAART in the MTCT-Plus family treatment model: role of depression in declining adherence over time.

PubMed

Byakika-Tusiime, Jayne; Crane, Johanna; Oyugi, Jessica H; Ragland, Kathleen; Kawuma, Annet; Musoke, Philippa; Bangsberg, David R

2009-06-01

We conducted a study to assess the effect of family-based treatment on adherence amongst HIV-infected parents and their HIV-infected children attending the Mother-To-Child-Transmission Plus program in Kampala, Uganda. Adherence was assessed using home-based pill counts and self-report. Mean adherence was over 94%. Depression was associated with incomplete adherence on multivariable analysis. Adherence declined over time. Qualitative interviews revealed lack of transportation money, stigma, clinical response to therapy, drug packaging, and cost of therapy may impact adherence. Our results indicate that providing ART to all eligible HIV-infected members in a household is associated with excellent adherence in both parents and children. Adherence to ART among new parents declines over time, even when patients receive treatment at no cost. Depression should be addressed as a potential barrier to adherence. Further study is necessary to assess the long-term impact of this family treatment model on adherence to ART in resource-limited settings.

Socio-Demographic and Clinical Characteristics are Not Clinically Useful Predictors of Refill Adherence in Patients with Hypertension

PubMed Central

Steiner, John F.; Ho, P. Michael; Beaty, Brenda L.; Dickinson, L. Miriam; Hanratty, Rebecca; Zeng, Chan; Tavel, Heather M.; Havranek, Edward P.; Davidson, Arthur J.; Magid, David J.; Estacio, Raymond O.

2009-01-01

Background Although many studies have identified patient characteristics or chronic diseases associated with medication adherence, the clinical utility of such predictors has rarely been assessed. We attempted to develop clinical prediction rules for adherence with antihypertensive medications in two health care delivery systems. Methods and Results Retrospective cohort studies of hypertension registries in an inner-city health care delivery system (N = 17176) and a health maintenance organization (N = 94297) in Denver, Colorado. Adherence was defined by acquisition of 80% or more of antihypertensive medications. A multivariable model in the inner-city system found that adherent patients (36.3% of the total) were more likely than non-adherent patients to be older, white, married, and acculturated in US society, to have diabetes or cerebrovascular disease, not to abuse alcohol or controlled substances, and to be prescribed less than three antihypertensive medications. Although statistically significant, all multivariate odds ratios were 1.7 or less, and the model did not accurately discriminate adherent from non-adherent patients (C-statistic = 0.606). In the health maintenance organization, where 72.1% of patients were adherent, significant but weak associations existed between adherence and older age, white race, the lack of alcohol abuse, and fewer antihypertensive medications. The multivariate model again failed to accurately discriminate adherent from non-adherent individuals (C-statistic = 0.576). Conclusions Although certain socio-demographic characteristics or clinical diagnoses are statistically associated with adherence to refills of antihypertensive medications, a combination of these characteristics is not sufficiently accurate to allow clinicians to predict whether their patients will be adherent with treatment. PMID:20031876

A Geometric Solution of a Cournot Ogilopoly with Nonidentical Firms.

ERIC Educational Resources Information Center

Sarkar, Jyotirmoy; Gupta, Barnali; Pal, Debashis

1998-01-01

Maintains that a proper understanding of the Augustin Cournot model of imperfect competition and strategic interactions among firms in various contexts is essential for economics education. Although most models rely on complicated algebra, this one requires nothing more than high school level geometry. Includes a graphical analysis. (MJP)

Estimating true instead of apparent survival using spatial Cormack-Jolly-Seber models

USGS Publications Warehouse

Schaub, Michael; Royle, J. Andrew

2014-01-01

Spatial CJS models enable study of dispersal and survival independent of study design constraints such as imperfect detection and size of the study area provided that some of the dispersing individuals remain in the study area. We discuss possible extensions of our model: alternative dispersal models and the inclusion of covariates and of a habitat suitability map.

Ignoring Imperfect Detection in Biological Surveys Is Dangerous: A Response to ‘Fitting and Interpreting Occupancy Models'

PubMed Central

Guillera-Arroita, Gurutzeta; Lahoz-Monfort, José J.; MacKenzie, Darryl I.; Wintle, Brendan A.; McCarthy, Michael A.

2014-01-01

In a recent paper, Welsh, Lindenmayer and Donnelly (WLD) question the usefulness of models that estimate species occupancy while accounting for detectability. WLD claim that these models are difficult to fit and argue that disregarding detectability can be better than trying to adjust for it. We think that this conclusion and subsequent recommendations are not well founded and may negatively impact the quality of statistical inference in ecology and related management decisions. Here we respond to WLD's claims, evaluating in detail their arguments, using simulations and/or theory to support our points. In particular, WLD argue that both disregarding and accounting for imperfect detection lead to the same estimator performance regardless of sample size when detectability is a function of abundance. We show that this, the key result of their paper, only holds for cases of extreme heterogeneity like the single scenario they considered. Our results illustrate the dangers of disregarding imperfect detection. When ignored, occupancy and detection are confounded: the same naïve occupancy estimates can be obtained for very different true levels of occupancy so the size of the bias is unknowable. Hierarchical occupancy models separate occupancy and detection, and imprecise estimates simply indicate that more data are required for robust inference about the system in question. As for any statistical method, when underlying assumptions of simple hierarchical models are violated, their reliability is reduced. Resorting in those instances where hierarchical occupancy models do no perform well to the naïve occupancy estimator does not provide a satisfactory solution. The aim should instead be to achieve better estimation, by minimizing the effect of these issues during design, data collection and analysis, ensuring that the right amount of data is collected and model assumptions are met, considering model extensions where appropriate. PMID:25075615

What's the Value of VAM (Value-Added Modeling)?

ERIC Educational Resources Information Center

Scherrer, Jimmy

2012-01-01

The use of value-added modeling (VAM) in school accountability is expanding, but deciding how to embrace VAM is difficult. Various experts say it's too unreliable, causes more harm than good, and has a big margin for error. Others assert VAM is imperfect but useful, and provides valuable feedback. A closer look at the models, and their use,…

The Study of Imperfection in Rough Set on the Field of Engineering and Education

NASA Astrophysics Data System (ADS)

Sheu, Tian-Wei; Liang, Jung-Chin; You, Mei-Li; Wen, Kun-Li

Based on the characteristic of rough set, rough set theory overlaps with many other theories, especially with fuzzy set theory, evidence theory and Boolean reasoning methods. And the rough set methodology has found many real-life applications, such as medical data analysis, finance, banking, engineering, voice recognition, image processing and others. Till now, there is rare research associating to this issue in the imperfection of rough set. Hence, the main purpose of this paper is to study the imperfection of rough set in the field of engineering and education. First of all, we preview the mathematics model of rough set, and a given two examples to enhance our approach, which one is the weighting of influence factor in muzzle noise suppressor, and the other is the weighting of evaluation factor in English learning. Third, we also apply Matlab to develop a complete human-machine interface type of toolbox in order to support the complex calculation and verification the huge data. Finally, some further suggestions are indicated for the research in the future.

Impact of the Chronic Care Model on medication adherence when patients perceive cost as a barrier.

PubMed

Mackey, Katherine; Parchman, Michael L; Leykum, Luci K; Lanham, Holly J; Noël, Polly H; Zeber, John E

2012-07-01

Cost burdens represent a significant barrier to medication adherence among chronically ill patients, yet financial pressures may be mitigated by clinical or organizational factors, such as treatment aligned with the Chronic Care Model (CCM). This study examines how perceptions of chronic illness care attenuate the relationship between adherence and cost burden. Surveys were administered to patients at 40 small community-based primary care practices. Medication adherence was assessed using the 4-item Morisky scale, while five cost-related items documented recent pharmacy restrictions. CCM experiences were assessed via the 20-item Patient Assessment of Chronic Illness Care (PACIC). Nested random effects models determined if chronic care perceptions modified the association between medication adherence and cost-related burden. Of 1823 respondents reporting diabetes and other chronic diseases, one-quarter endorsed intrapersonal adherence barriers, while 23% restricted medication due of cost. Controlling for age and health status, the relationship between medication cost and CCM with adherence was significant; including PACIC scores attenuated cost-related problems patients with adequate or problematic adherence behavior. Patients experiencing treatment more consistent with the CCM reported better adherence and lower cost-related burden. Fostering highly activated patients and shared clinical decision making may help alleviate medication cost pressures and improve adherence. Published by Elsevier Ltd.

Predicting adherence to combination antiretroviral therapy for HIV in Tanzania: A test of an extended theory of planned behaviour model.

PubMed

Banas, Kasia; Lyimo, Ramsey A; Hospers, Harm J; van der Ven, Andre; de Bruin, Marijn

2017-10-01

Combination antiretroviral therapy (cART) for HIV is widely available in sub-Saharan Africa. Adherence is crucial to successful treatment. This study aimed to apply an extended theory of planned behaviour (TPB) model to predict objectively measured adherence to cART in Tanzania. Prospective observational study (n = 158) where patients completed questionnaires on demographics (Month 0), socio-cognitive variables including intentions (Month 1), and action planning and self-regulatory processes hypothesised to mediate the intention-behaviour relationship (Month 3), to predict adherence (Month 5). Taking adherence was measured objectively using the Medication Events Monitoring System (MEMS) caps. Model tests were conducted using regression and bootstrap mediation analyses. Perceived behavioural control (PBC) was positively (β = .767, p < .001, R 2  = 57.5%) associated with adherence intentions. Intentions only exercised an indirect effect on adherence (B = 1.29 [0.297-3.15]) through self-regulatory processes (B = 1.10 [0.131-2.87]). Self-regulatory processes (β = .234, p = .010, R 2  = 14.7%) predicted better adherence. This observational study using an objective behavioural measure, identified PBC as the main driver of adherence intentions. The effect of intentions on adherence was only indirect through self-regulatory processes, which were the main predictor of objectively assessed adherence.

A Bernoulli Formulation of the Land-Use Portfolio Model

USGS Publications Warehouse

Champion, Richard A.

2008-01-01

Decision making for natural-hazards mitigation can be sketched as knowledge available in advance (a priori), knowledge available later (a posteriori), and how consequences of the mitigation decision might be viewed once future outcomes are known. Two outcomes - mitigating for a hazard event that will occur, and not mitigating for a hazard event that will not occur - can be considered narrowly correct. Two alternative outcomes - mitigating for a hazard event that will not occur, and not mitigating for a hazard event that will occur - can be considered narrowly incorrect. The dilemma facing the decision maker is that mitigation choices must be made before the event, and often must be made with imperfect statistical techniques and imperfect data.

Buckling Analysis of Single and Multi Delamination In Composite Beam Using Finite Element Method

NASA Astrophysics Data System (ADS)

Simanjorang, Hans Charles; Syamsudin, Hendri; Giri Suada, Muhammad

2018-04-01

Delamination is one type of imperfection in structure which found usually in the composite structure. Delamination may exist due to some factors namely in-service condition where the foreign objects hit the composite structure and creates inner defect and poor manufacturing that causes the initial imperfections. Composite structure is susceptible to the compressive loading. Compressive loading leads the instability phenomenon in the composite structure called buckling. The existence of delamination inside of the structure will cause reduction in buckling strength. This paper will explain the effect of delamination location to the buckling strength. The analysis will use the one-dimensional modelling approach using two- dimensional finite element method.

Modeling the economic impact of medication adherence in type 2 diabetes: a theoretical approach.

PubMed

Cobden, David S; Niessen, Louis W; Rutten, Frans Fh; Redekop, W Ken

2010-09-07

While strong correlations exist between medication adherence and health economic outcomes in type 2 diabetes, current economic analyses do not adequately consider them. We propose a new approach to incorporate adherence in cost-effectiveness analysis. We describe a theoretical approach to incorporating the effect of adherence when estimating the long-term costs and effectiveness of an antidiabetic medication. This approach was applied in a Markov model which includes common diabetic health states. We compared two treatments using hypothetical patient cohorts: injectable insulin (IDM) and oral (OAD) medications. Two analyses were performed, one which ignored adherence (analysis 1) and one which incorporated it (analysis 2). Results from the two analyses were then compared to explore the extent to which adherence may impact incremental cost-effectiveness ratios. In both analyses, IDM was more costly and more effective than OAD. When adherence was ignored, IDM generated an incremental cost-effectiveness of $12,097 per quality-adjusted life-year (QALY) gained versus OAD. Incorporation of adherence resulted in a slightly higher ratio ($16,241/QALY). This increase was primarily due to better adherence with OAD than with IDM, and the higher direct medical costs for IDM. Incorporating medication adherence into economic analyses can meaningfully influence the estimated cost-effectiveness of type 2 diabetes treatments, and should therefore be considered in health care decision-making. Future work on the impact of adherence on health economic outcomes, and validation of different approaches to modeling adherence, is warranted.

Verb Aspect and the Activation of Event Knowledge

PubMed Central

Ferretti, Todd R.; Kutas, Marta; McRae, Ken

2011-01-01

The authors show that verb aspect influences the activation of event knowledge with 4 novel results. First, common locations of events (e.g., arena) are primed following verbs with imperfective aspect (e.g., was skating) but not verbs with perfect aspect (e.g., had skated). Second, people generate more locative prepositional phrases as completions to sentence fragments with imperfective than those with perfect aspect. Third, the amplitude of the N400 component to location nouns varies as a function of aspect and typicality, being smallest for imperfective sentences with highly expected locations and largest for imperfective sentences with less expected locations. Fourth, the amplitude of a sustained frontal negativity spanning prepositional phrases is larger following perfect than following imperfective aspect. Taken together, these findings suggest a dynamic interplay between event knowledge and the linguistic stream. PMID:17201561

Exercise, Affect, and Adherence: An Integrated Model and a Case for Self-Paced Exercise

PubMed Central

Williams, David M.

2014-01-01

This paper reviews research relevant to a proposed conceptual model of exercise adherence that integrates the dual mode model and hedonic theory. Exercise intensity is posited to influence affective response to exercise via interoceptive (e.g., ventilatory drive) and cognitive (e.g., perceived autonomy) pathways; affective response to exercise is posited to influence exercise adherence via anticipated affective response to future exercise. The potential for self-paced exercise to enhance exercise adherence is examined in the context of the proposed model and suggestions are given for future research. Further evidence in support of self-paced exercise could have implications for exercise prescription, especially among overweight, sedentary adults, who are most in need of interventions that enhance adherence to exercise programs. PMID:18971508

OPEC behavior

NASA Astrophysics Data System (ADS)

Yang, Bo

This thesis aims to contribute to a further understanding of the real dynamics of OPEC production behavior and its impacts on the world oil market. A literature review in this area shows that the existing studies on OPEC still have some major deficiencies in theoretical interpretation and empirical estimation technique. After a brief background review in chapter 1, chapter 2 tests Griffin's market-sharing cartel model on the post-Griffin time horizon with a simultaneous system of equations, and an innovative hypothesis of OPEC's behavior (Saudi Arabia in particular) is then proposed based on the estimation results. Chapter 3 first provides a conceptual analysis of OPEC behavior under the framework of non-cooperative collusion with imperfect information. An empirical model is then constructed and estimated. The results of the empirical studies in this thesis strongly support the hypothesis that OPEC has operated as a market-sharing cartel since the early 1980s. In addition, the results also provide some support of the theory of non-cooperative collusion under imperfect information. OPEC members collude under normal circumstances and behave competitively at times in response to imperfect market signals of cartel compliance and some internal attributes. Periodic joint competition conduct plays an important role in sustaining the collusion in the long run. Saudi Arabia acts as the leader of the cartel, accommodating intermediate unfavorable market development and punishing others with a tit-for-tat strategy in extreme circumstances.

Influence of imperfect end boundary condition on the nonlocal dynamics of CNTs

NASA Astrophysics Data System (ADS)

Fathi, Reza; Lotfan, Saeed; Sadeghi, Morteza H.

2017-03-01

Imperfections that unavoidably occur during the fabrication process of carbon nanotubes (CNTs) have a significant influence on the vibration behavior of CNTs. Among these imperfections, the boundary condition defect is studied in this investigation based on the nonlocal elasticity theory. To this end, a mathematical model of the non-ideal end condition in a cantilever CNT is developed by a strongly non-linear spring to study its effect on the vibration behavior. The weak form equation of motion is derived via Hamilton's principle and solved based on Rayleigh-Ritz approach. Once the frequency response function (FRF) of the CNT is simulated, it is found that the defect parameter injects noise to the FRF in the range of lower frequencies and as a result the small scale effect on the FRF remains undisturbed in high frequency ranges. Besides, in this work a process is introduced to estimate the nonlocal and defect parameters for establishing the mathematical model of the CNT based on FRF, which can be competitive because of its lower instrumentation and data analysis costs. The estimation process relies on the resonance frequencies and the magnitude of noise in the frequency response function of the CNT. The results show that the constructed dynamic response of the system based on estimated parameters is in good agreement with the original response of the CNT.

Buckling Testing and Analysis of Honeycomb Sandwich Panel Arc Segments of a Full-Scale Fairing Barrel. Part 2; 6-Ply In-Autoclave Facesheets

NASA Technical Reports Server (NTRS)

Pineda, Evan J.; Meyers, David E.; Kosareo, Daniel N.; Zalewski, Bart F.; Dixon, Genevieve D.

2013-01-01

Four honeycomb sandwich panel types, representing 1/16th arc segments of a 10-m diameter barrel section of the Heavy Lift Launch Vehicle (HLLV), were manufactured and tested under the NASA Composites for Exploration program and the NASA Constellation Ares V program. Two configurations were chosen for the panels: 6-ply facesheets with 1.125 in. honeycomb core and 8-ply facesheets with 1.000 in. honeycomb core. Additionally, two separate carbon fiber/epoxy material systems were chosen for the facesheets: in-autoclave IM7/977-3 and out-of-autoclave T40-800b/5320-1. Smaller 3- by 5-ft panels were cut from the 1/16th barrel sections. These panels were tested under compressive loading at the NASA Langley Research Center (LaRC). Furthermore, linear eigenvalue and geometrically nonlinear finite element analyses were performed to predict the compressive response of each 3- by 5-ft panel. This manuscript summarizes the experimental and analytical modeling efforts pertaining to the panels composed of 6-ply, IM7/977-3 facesheets (referred to as Panels B-1 and B-2). To improve the robustness of the geometrically nonlinear finite element model, measured surface imperfections were included in the geometry of the model. Both the linear and nonlinear models yield good qualitative and quantitative predictions. Additionally, it was correctly predicted that the panel would fail in buckling prior to failing in strength. Furthermore, several imperfection studies were performed to investigate the influence of geometric imperfections, fiber angle misalignments, and three-dimensional (3-D) effects on the compressive response of the panel.

Buckling Testing and Analysis of Honeycomb Sandwich Panel Arc Segments of a Full-Scale Fairing Barrel Part 1: 8-Ply In-Autoclave Facesheets. Part 1; 8-Ply In-Autoclave Facesheets

NASA Technical Reports Server (NTRS)

Myers, David E.; Pineda, Evan J.; Zalewski, Bart F.; Kosareo, Daniel N.; Kellas, Sotiris

2013-01-01

Four honeycomb sandwich panels, representing 1/16th arc segments of a 10-m diameter barrel section of the heavy lift launch vehicle, were manufactured under the NASA Composites for Exploration program and the NASA Space Launch Systems program. Two configurations were chosen for the panels: 6-ply facesheets with 1.125 in. honeycomb core and 8-ply facesheets with 1.000 in. honeycomb core. Additionally, two separate carbon fiber/epoxy material systems were chosen for the facesheets: inautoclave IM7/977-3 and out-of-autoclave T40-800b/5320-1. Smaller 3.00- by 5.00-ft panels were cut from the 1/16th barrel sections. These panels were tested under compressive loading at the NASA Langley Research Center. Furthermore, linear eigenvalue and geometrically nonlinear finite element analysis was performed to predict the compressive response of the 3.00- by 5.00-ft panels. This manuscript summarizes the experimental and analytical modeling efforts pertaining to the panel composed of 8-ply, IM7/977-3 facesheets (referred to Panel A). To improve the robustness of the geometrically nonlinear finite element model, measured surface imperfections were included in the geometry of the model. Both the linear and nonlinear models yield good qualitative and quantitative predictions. Additionally, it was predicted correctly that the panel would fail in buckling prior to failing in strength. Furthermore, several imperfection studies were performed to investigate the influence of geometric imperfections, fiber misalignments, and three-dimensional (3 D) effects on the compressive response of the panel.

Imperfect pathogen detection from non-invasive skin swabs biases disease inference

USGS Publications Warehouse

DiRenzo, Graziella V.; Grant, Evan H. Campbell; Longo, Ana; Che-Castaldo, Christian; Zamudio, Kelly R.; Lips, Karen

2018-01-01

1. Conservation managers rely on accurate estimates of disease parameters, such as pathogen prevalence and infection intensity, to assess disease status of a host population. However, these disease metrics may be biased if low-level infection intensities are missed by sampling methods or laboratory diagnostic tests. These false negatives underestimate pathogen prevalence and overestimate mean infection intensity of infected individuals. 2. Our objectives were two-fold. First, we quantified false negative error rates of Batrachochytrium dendrobatidis on non-invasive skin swabs collected from an amphibian community in El Copé, Panama. We swabbed amphibians twice in sequence, and we used a recently developed hierarchical Bayesian estimator to assess disease status of the population. Second, we developed a novel hierarchical Bayesian model to simultaneously account for imperfect pathogen detection from field sampling and laboratory diagnostic testing. We evaluated the performance of the model using simulations and varying sampling design to quantify the magnitude of bias in estimates of pathogen prevalence and infection intensity. 3. We show that Bd detection probability from skin swabs was related to host infection intensity, where Bd infections < 10 zoospores have < 95% probability of being detected. If imperfect Bd detection was not considered, then Bd prevalence was underestimated by as much as 16%. In the Bd-amphibian system, this indicates a need to correct for imperfect pathogen detection caused by skin swabs in persisting host communities with low-level infections. More generally, our results have implications for study designs in other disease systems, particularly those with similar objectives, biology, and sampling decisions. 4. Uncertainty in pathogen detection is an inherent property of most sampling protocols and diagnostic tests, where the magnitude of bias depends on the study system, type of infection, and false negative error rates. Given that it may be difficult to know this information in advance, we advocate that the most cautious approach is to assume all errors are possible and to accommodate them by adjusting sampling designs. The modeling framework presented here improves the accuracy in estimating pathogen prevalence and infection intensity.

Imperfect duplicate insertions type of mutations in plasmepsin V modulates binding properties of PEXEL motifs of export proteins in Indian Plasmodium vivax.

PubMed

Rawat, Manmeet; Vijay, Sonam; Gupta, Yash; Tiwari, Pramod Kumar; Sharma, Arun

2013-01-01

Plasmepsin V (PM-V) have functionally conserved orthologues across the Plasmodium genus who's binding and antigenic processing at the PEXEL motifs for export about 200-300 essential proteins is important for the virulence and viability of the causative Plasmodium species. This study was undertaken to determine P. vivax plasmepsin V Ind (PvPM-V-Ind) PEXEL motif export pathway for pathogenicity-related proteins/antigens export thereby altering plasmodium exportome during erythrocytic stages. We identify and characterize Plasmodium vivax plasmepsin-V-Ind (mutant) gene by cloning, sequence analysis, in silico bioinformatic protocols and structural modeling predictions based on docking studies on binding capacity with PEXEL motifs processing in terms of binding and accessibility of export proteins. Cloning and sequence analysis for genetic diversity demonstrates PvPM-V-Ind (mutant) gene is highly conserved among all isolates from different geographical regions of India. Imperfect duplicate insertion types of mutations (SVSE from 246-249 AA and SLSE from 266-269 AA) were identified among all Indian isolates in comparison to P.vivax Sal-1 (PvPM-V-Sal 1) isolate. In silico bioinformatics interaction studies of PEXEL peptide and active enzyme reveal that PvPM-V-Ind (mutant) is only active in endoplasmic reticulum lumen and membrane embedding is essential for activation of plasmepsin V. Structural modeling predictions based on docking studies with PEXEL motif show significant variation in substrate protein binding of these imperfect mutations with data mined PEXEL sequences. The predicted variation in the docking score and interacting amino acids of PvPM-V-Ind (mutant) proteins with PEXEL and lopinavir suggests a modulation in the activity of PvPM-V in terms of binding and accessibility at these sites. Our functional modeled validation of PvPM-V-Ind (mutant) imperfect duplicate insertions with data mined PEXEL sequences leading to altered binding and substrate accessibility of the enzyme makes it a plausible target to investigate export mechanisms for in silico virtual screening and novel pharmacophore designing.

Imperfect Duplicate Insertions Type of Mutations in Plasmepsin V Modulates Binding Properties of PEXEL Motifs of Export Proteins in Indian Plasmodium vivax

PubMed Central

Rawat, Manmeet; Vijay, Sonam; Gupta, Yash; Tiwari, Pramod Kumar; Sharma, Arun

2013-01-01

Introduction Plasmepsin V (PM-V) have functionally conserved orthologues across the Plasmodium genus who's binding and antigenic processing at the PEXEL motifs for export about 200–300 essential proteins is important for the virulence and viability of the causative Plasmodium species. This study was undertaken to determine P. vivax plasmepsin V Ind (PvPM-V-Ind) PEXEL motif export pathway for pathogenicity-related proteins/antigens export thereby altering plasmodium exportome during erythrocytic stages. Method We identify and characterize Plasmodium vivax plasmepsin-V-Ind (mutant) gene by cloning, sequence analysis, in silico bioinformatic protocols and structural modeling predictions based on docking studies on binding capacity with PEXEL motifs processing in terms of binding and accessibility of export proteins. Results Cloning and sequence analysis for genetic diversity demonstrates PvPM-V-Ind (mutant) gene is highly conserved among all isolates from different geographical regions of India. Imperfect duplicate insertion types of mutations (SVSE from 246–249 AA and SLSE from 266–269 AA) were identified among all Indian isolates in comparison to P.vivax Sal-1 (PvPM-V-Sal 1) isolate. In silico bioinformatics interaction studies of PEXEL peptide and active enzyme reveal that PvPM-V-Ind (mutant) is only active in endoplasmic reticulum lumen and membrane embedding is essential for activation of plasmepsin V. Structural modeling predictions based on docking studies with PEXEL motif show significant variation in substrate protein binding of these imperfect mutations with data mined PEXEL sequences. The predicted variation in the docking score and interacting amino acids of PvPM-V-Ind (mutant) proteins with PEXEL and lopinavir suggests a modulation in the activity of PvPM-V in terms of binding and accessibility at these sites. Conclusion/Significance Our functional modeled validation of PvPM-V-Ind (mutant) imperfect duplicate insertions with data mined PEXEL sequences leading to altered binding and substrate accessibility of the enzyme makes it a plausible target to investigate export mechanisms for in silico virtual screening and novel pharmacophore designing. PMID:23555891

A Structural Equation Model of HIV-related Symptoms, Depressive Symptoms, and Medication Adherence.

PubMed

Yoo-Jeong, Moka; Waldrop-Valverde, Drenna; McCoy, Katryna; Ownby, Raymond L

2016-05-01

Adherence to combined antiretroviral therapy (cART) remains critical in management of HIV infection. This study evaluated depression as a potential mechanism by which HIV-related symptoms affect medication adherence and explored if particular clusters of HIV symptoms are susceptible to this mechanism. Baseline data from a multi-visit intervention study were analyzed among 124 persons living with HIV (PLWH). A bifactor model showed two clusters of HIV-related symptom distress: general HIV-related symptoms and gastrointestinal (GI) symptoms. Structural equation modeling showed that both general HIV-related symptoms and GI symptoms were related to higher levels of depressive symptoms, and higher levels of depressive symptoms were related to lower levels of medication adherence. Although general HIV-related symptoms and GI symptoms were not directly related to adherence, they were indirectly associated with adherence via depression. The findings highlight the importance of early recognition and evaluation of symptoms of depression, as well as the underlying physical symptoms that might cause depression, to improve medication adherence.

A Structural Equation Model of HIV-related Symptoms, Depressive Symptoms, and Medication Adherence

PubMed Central

Yoo-Jeong, Moka; Waldrop-Valverde, Drenna; McCoy, Katryna; Ownby, Raymond L

2016-01-01

Adherence to combined antiretroviral therapy (cART) remains critical in management of HIV infection. This study evaluated depression as a potential mechanism by which HIV-related symptoms affect medication adherence and explored if particular clusters of HIV symptoms are susceptible to this mechanism. Baseline data from a multi-visit intervention study were analyzed among 124 persons living with HIV (PLWH). A bifactor model showed two clusters of HIV-related symptom distress: general HIV-related symptoms and gastrointestinal (GI) symptoms. Structural equation modeling showed that both general HIV-related symptoms and GI symptoms were related to higher levels of depressive symptoms, and higher levels of depressive symptoms were related to lower levels of medication adherence. Although general HIV-related symptoms and GI symptoms were not directly related to adherence, they were indirectly associated with adherence via depression. The findings highlight the importance of early recognition and evaluation of symptoms of depression, as well as the underlying physical symptoms that might cause depression, to improve medication adherence. PMID:27695710

Why Some Imperfectives Are Interpreted Imperfectly: A Study of Chinese Learners of Japanese

ERIC Educational Resources Information Center

Gabriele, Alison; McClure, William

2011-01-01

The study investigates whether advanced second language (L2) learners can extend beyond the grammatical properties of the first language (L1) to successfully acquire tense and aspect. We examine the acquisition of the semantics of the imperfective marker "te-iru" in Japanese by native speakers of Mandarin Chinese, a language that…

Medication adherence in the management of nocturia: challenges and solutions

PubMed Central

Jayadevappa, Ravishankar; Newman, Diane K; Chhatre, Sumedha; Wein, Alan J

2015-01-01

Objective Nocturia affects millions of men and women. No prior reviews or meta-analyses have explored the issue of adherence in nocturia patients. The objective of our study was to examine the attributes and their interaction that might impact pharmacological adherence in nocturia care using a conceptual model of adherence. Materials and methods A literature search of the Medline, PubMed, Embase, PsycInfo, and CINAHL databases for studies published between January 1990 and June 2014 was conducted. We developed a conceptual model in order to facilitate our review. Results Currently, multiple treatment options for nocturia exist, depending on the underlying cause. Adherence to nocturia treatment and outcomes are complex and intertwined, and nonadherence to nocturia treatment is common. In 15 studies meeting eligibility criteria, behavioral and pharmacologic interventions for nocturia were associated with reduced nocturia symptoms. Urinary symptoms that are associated with nocturia need individualized management depending on renal and hepatic function, medical comorbidities, and ongoing medication use in a patient. Another important factor related to adherence is the bother. Although nocturia is defined as nighttime-voiding frequency of one or more, not all persons may find this bothersome. The degree of bother is subjective, and may change from person to person. However, there is no information related to the association between bother and adherence to medication or behavioral treatments for nocturia. Medication dosing convenience, preference, and cost play important roles in adherence. We present a patient-centered conceptual model that brings together the various dimensions of medication adherence for nocturia. Conclusion Few studies have explored adherence to medication and related factors in the care of nocturia. Our conceptual model can aid development of interventions to improve adherence to nocturia medications. PMID:25609929

Optimal Government Subsidies to Universities in the Face of Tuition and Enrollment Constraints

ERIC Educational Resources Information Center

Easton, Stephen T.; Rockerbie, Duane W.

2008-01-01

This paper develops a simple static model of an imperfectly competitive university operating under government-imposed constraints on the ability to raise tuition fees and increase enrollments. The model has particular applicability to Canadian universities. Assuming an average cost pricing rule, rules for adequate government subsidies (operating…

Computer models and the evidence of anthropogenic climate change: An epistemology of variety-of-evidence inferences and robustness analysis.

PubMed

Vezér, Martin A

2016-04-01

To study climate change, scientists employ computer models, which approximate target systems with various levels of skill. Given the imperfection of climate models, how do scientists use simulations to generate knowledge about the causes of observed climate change? Addressing a similar question in the context of biological modelling, Levins (1966) proposed an account grounded in robustness analysis. Recent philosophical discussions dispute the confirmatory power of robustness, raising the question of how the results of computer modelling studies contribute to the body of evidence supporting hypotheses about climate change. Expanding on Staley's (2004) distinction between evidential strength and security, and Lloyd's (2015) argument connecting variety-of-evidence inferences and robustness analysis, I address this question with respect to recent challenges to the epistemology robustness analysis. Applying this epistemology to case studies of climate change, I argue that, despite imperfections in climate models, and epistemic constraints on variety-of-evidence reasoning and robustness analysis, this framework accounts for the strength and security of evidence supporting climatological inferences, including the finding that global warming is occurring and its primary causes are anthropogenic. Copyright © 2016 Elsevier Ltd. All rights reserved.

Reliability modelling and analysis of a multi-state element based on a dynamic Bayesian network

NASA Astrophysics Data System (ADS)

Li, Zhiqiang; Xu, Tingxue; Gu, Junyuan; Dong, Qi; Fu, Linyu

2018-04-01

This paper presents a quantitative reliability modelling and analysis method for multi-state elements based on a combination of the Markov process and a dynamic Bayesian network (DBN), taking perfect repair, imperfect repair and condition-based maintenance (CBM) into consideration. The Markov models of elements without repair and under CBM are established, and an absorbing set is introduced to determine the reliability of the repairable element. According to the state-transition relations between the states determined by the Markov process, a DBN model is built. In addition, its parameters for series and parallel systems, namely, conditional probability tables, can be calculated by referring to the conditional degradation probabilities. Finally, the power of a control unit in a failure model is used as an example. A dynamic fault tree (DFT) is translated into a Bayesian network model, and subsequently extended to a DBN. The results show the state probabilities of an element and the system without repair, with perfect and imperfect repair, and under CBM, with an absorbing set plotted by differential equations and verified. Through referring forward, the reliability value of the control unit is determined in different kinds of modes. Finally, weak nodes are noted in the control unit.

Extent of agreement between the body fluid model of Sysmex XN-20 and the manual microscopy method.

PubMed

Huang, Wei-Hua; Lu, Lin-Peng; Wu, Kang; Guo, Fang-Yu; Guo, Jie; Yu, Jing-Long; Zhou, Dao-Yin; Sun, Yi; Deng, An-Mei

2017-09-01

Although the correlations concerning cellular component analysis between the Sysmex XN-20 body fluid (BF) model and manual microscopy have been investigated by several studies, the extent of agreement between these two methods has not been investigated. A total of 90 BF samples were prospectively collected and analyzed using the Sysmex XN-20 BF model and microscopy. The extent of agreement between these two methods was evaluated using the Bland-Altman approach. Receiver operating characteristic (ROC) curve analysis was employed to evaluate the diagnostic accuracy of high-fluorescence (HF) BF cells for malignant diseases. The agreements of white blood cell (WBC), red blood cell (RBC), and percentages of neutrophils, lymphocytes, and monocytes between the Sysmex XN-20 BF model and manual microscopy were imperfect. The areas under the ROC curves for absolute and relative HF cells were 0.67 (95% confidence interval [CI]: 0.56-0.78) and 0.60 (95% CI: 0.48-0.72), respectively. Due to the Sysmex XN-20 BF model's imperfect agreement with manual microscopy and its weak diagnostic accuracy for malignant diseases, the current evidence does not support replacing manual microscopy with this model in clinical practice. © 2016 Wiley Periodicals, Inc.

Multistate transitional models for measuring adherence to breast cancer screening: A population-based longitudinal cohort study with over two million women.

PubMed

Sutradhar, R; Gu, S; Paszat, L F

2017-06-01

Objective Prior work on the disparities among women in breast cancer screening adherence has been methodologically limited. This longitudinal study determines and examines the factors associated with becoming adherent. Methods In a cohort of Canadian women aged 50-74, a three-state transitional model was used to examine adherence to screening for breast cancer. The proportion of time spent being non-adherent with screening was calculated for each woman during her observation window. Using age as the time scale, a relative rate multivariable regression was implemented under the three-state transitional model, to examine the association between covariates (all time-varying) and the rate of becoming adherent. Results The cohort consisted of 2,537,960 women with a median follow-up of 8.46 years. Nearly 31% of women were continually up-to-date with breast screening. Once a woman was non-adherent, the rate of becoming adherent was higher among longer term residents (relative rate = 1.289, 95% confidence interval 1.275-1.302), those from wealthier neighbourhoods, and those who had an identifiable primary care provider who was female or had graduated in Canada. Conclusion Individual and physician-level characteristics play an important role in a woman's adherence to screening. This work improves the quality of evidence regarding disparities among women in adherence to breast cancer screening and provides a novel methodological foundation to investigate adherence for other types of screening, including cervix and colorectal cancer screening.

Regulating automobile pollution under certainty, competition, and imperfect information

DOE Office of Scientific and Technical Information (OSTI.GOV)

Innes, R.

1996-09-01

This paper studies an integrated economic model of automobile emissions that incorporates consumer mileage, automobile features, and fuel content choices. Optimal regulatory policies are shown to include fuel content standards, gasoline taxes, and direct automobile regulation or taxation.

Evaluation of Planetary Boundary Layer Scheme Sensitivities for the Purpose of Parameter Estimation

EPA Science Inventory

Meteorological model errors caused by imperfect parameterizations generally cannot be overcome simply by optimizing initial and boundary conditions. However, advanced data assimilation methods are capable of extracting significant information about parameterization behavior from ...

MODELING POPULATION EXPOSURES TO OUTDOOR SOURCES OF HAZARDOUS AIR POLLUTANTS

EPA Science Inventory

Accurate assessment of human exposures is an important part of environmental health effects research. However, most air pollution epidemiology studies rely upon imperfect surrogates of personal exposures, such as information based on available central-site outdoor concentration ...

Medication adherence in schizophrenia: The role of insight, therapeutic alliance and perceived trauma associated with psychiatric care.

PubMed

Tessier, Arnaud; Boyer, Laurent; Husky, Mathilde; Baylé, Franck; Llorca, Pierre-Michel; Misdrahi, David

2017-11-01

Medication non adherence in schizophrenia is a major cause of relapse and hospitalization and remains for clinicians an important challenge. This study investigates the associations between insight, therapeutic alliance, perceived trauma related to psychiatric treatment and medication adherence in patients with schizophrenia. In this multicenter study, 72 patients were assessed regarding symptomatology, self-reported adherence with medication, insight, medication side-effects, therapeutic alliance and perceived trauma related to psychiatric treatment. Structural Equation Modeling (SEM) was used to test predicted paths among these variables. The data fit a model in which medication adherence was directly predicted by insight, therapeutic alliance and perceived trauma related to psychiatric treatment. Perceived trauma moderates the role of insight on medication adherence. The final model showed good fit, based on four reliable indices. Greater adherence was correlated with higher insight, higher therapeutic alliance and lower perceived trauma. These three variables appear to be important determinants of patient's medication adherence. Medication adherence could be enhanced by reducing perceived trauma and by increasing insight. The need for mental health providers to acknowledge patients' potentially traumatic experience with psychiatric treatment and the need to encourage greater involvement in care are discussed. Copyright © 2017 Elsevier B.V. All rights reserved.

A Developmental Perspective on the Imperfective Paradox

ERIC Educational Resources Information Center

Kazanina, Nina; Phillips, Colin

2007-01-01

Imperfective or progressive verb morphology makes it possible to use the name of a whole event to refer to an activity that is clearly not a complete instance of that event, leading to what is known as the Imperfective Paradox. For example, a sentence like "John was building a house" does not entail that a house ever got built. The Imperfective…

Assessment of imperfect detection of blister rust in whitebark pine within the Greater Yellowstone Ecosystem

USGS Publications Warehouse

Wright, Wilson J.; Irvine, Kathryn M.

2017-01-01

We examined data on white pine blister rust (blister rust) collected during the monitoring of whitebark pine trees in the Greater Yellowstone Ecosystem (from 2004-2015). Summaries of repeat observations performed by multiple independent observers are reviewed and discussed. These summaries show variability among observers and the potential for errors being made in blister rust status. Based on this assessment, we utilized occupancy models to analyze blister rust prevalence while explicitly accounting for imperfect detection. Available covariates were used to model both the probability of a tree being infected with blister rust and the probability of an observer detecting the infection. The fitted model provided strong evidence that the probability of blister rust infection increases as tree diameter increases and decreases as site elevation increases. Most importantly, we found evidence of heterogeneity in detection probabilities related to tree size and average slope of a transect. These results suggested that detecting the presence of blister rust was more difficult in larger trees. Also, there was evidence that blister rust was easier to detect on transects located on steeper slopes. Our model accounted for potential impacts of observer experience on blister rust detection probabilities and also showed moderate variability among the different observers in their ability to detect blister rust. Based on these model results, we suggest that multiple observer sampling continue in future field seasons in order to allow blister rust prevalence estimates to be corrected for imperfect detection. We suggest that the multiple observer effort be spread out across many transects (instead of concentrated at a few each field season) while retaining the overall proportion of trees with multiple observers around 5-20%. Estimates of prevalence are confounded with detection unless it is explicitly accounted for in an analysis and we demonstrate how an occupancy model can be used to do account for this source of observation error.

Analysis and testing of axial compression in imperfect slender truss struts

NASA Technical Reports Server (NTRS)

Lake, Mark S.; Georgiadis, Nicholas

1990-01-01

The axial compression of imperfect slender struts for large space structures is addressed. The load-shortening behavior of struts with initially imperfect shapes and eccentric compressive end loading is analyzed using linear beam-column theory and results are compared with geometrically nonlinear solutions to determine the applicability of linear analysis. A set of developmental aluminum clad graphite/epoxy struts sized for application to the Space Station Freedom truss are measured to determine their initial imperfection magnitude, load eccentricity, and cross sectional area and moment of inertia. Load-shortening curves are determined from axial compression tests of these specimens and are correlated with theoretical curves generated using linear analysis.

Passive Faraday-mirror attack in a practical two-way quantum-key-distribution system

NASA Astrophysics Data System (ADS)

Sun, Shi-Hai; Jiang, Mu-Sheng; Liang, Lin-Mei

2011-06-01

The Faraday mirror (FM) plays a very important role in maintaining the stability of two-way plug-and-play quantum key distribution (QKD) systems. However, the practical FM is imperfect, which will not only introduce an additional quantum bit error rate (QBER) but also leave a loophole for Eve to spy the secret key. In this paper we propose a passive Faraday mirror attack in two-way QKD system based on the imperfection of FM. Our analysis shows that if the FM is imperfect, the dimension of Hilbert space spanned by the four states sent by Alice is three instead of two. Thus Eve can distinguish these states with a set of Positive Operator Valued Measure (POVM) operators belonging to three-dimension space, which will reduce the QBER induced by her attack. Furthermore, a relationship between the degree of the imperfection of FM and the transmittance of the practical QKD system is obtained. The results show that the probability that Eve loads her attack successfully depends on the degree of the imperfection of FM rapidly, but the QBER induced by Eve’s attack changes slightly with the degree of the FM imperfection.

Psychological model of ART adherence behaviors in persons living with HIV/AIDS in Mexico: a structural equation analysis.

PubMed

Sagarduy, José Luis Ybarra; López, Julio Alfonso Piña; Ramírez, Mónica Teresa González; Dávila, Luis Enrique Fierros

2017-09-04

The objective of this study has been to test the ability of variables of a psychological model to predict antiretroviral therapy medication adherence behavior. We have conducted a cross-sectional study among 172 persons living with HIV/AIDS (PLWHA), who completed four self-administered assessments: 1) the Psychological Variables and Adherence Behaviors Questionnaire, 2) the Stress-Related Situation Scale to assess the variable of Personality, 3) The Zung Depression Scale, and 4) the Duke-UNC Functional Social Support Questionnaire. Structural equation modeling was used to construct a model to predict medication adherence behaviors. Out of all the participants, 141 (82%) have been considered 100% adherent to antiretroviral therapy. Structural equation modeling has confirmed the direct effect that personality (decision-making and tolerance of frustration) has on motives to behave, or act accordingly, which was in turn directly related to medication adherence behaviors. In addition, these behaviors have had a direct and significant effect on viral load, as well as an indirect effect on CD4 cell count. The final model demonstrates the congruence between theory and data (x2/df. = 1.480, goodness of fit index = 0.97, adjusted goodness of fit index = 0.94, comparative fit index = 0.98, root mean square error of approximation = 0.05), accounting for 55.7% of the variance. The results of this study support our theoretical model as a conceptual framework for the prediction of medication adherence behaviors in persons living with HIV/AIDS. Implications for designing, implementing, and evaluating intervention programs based on the model are to be discussed.

Why do persons with bipolar disorder stop their medication?

PubMed

Devulapalli, Kavi K; Ignacio, Rosalinda V; Weiden, Peter; Cassidy, Kristin A; Williams, Tiffany D; Safavi, Roknedin; Blow, Frederic C; Sajatovic, Martha

2010-01-01

Non-adherence to maintenance medication regimens is a major problem, limiting outcomes for many persons with bipolar disorder. The aim of this paper is to determine the most relevant aspects of adherence attitudes in a sample of bipolar patients selected for problems with adherence behavior. Among a larger sample of bipolar disorder patients participating in a prospective follow-up study (N = 140), a subsample of patients were selected for non-adherent behavior defined as missing ≥ 30% of medication during the past month (n = 27; 19.3%). Adherence attitudes were assessed with the Rating of Medication Influences scale (ROMI), a self-reported attitudinal measure assessing reasons for and against adherence. Multiple logistic regression models for non-adherence vs. adherence were estimated with each of the 19 ROMI items in the model, while controlling for sex, age, ethnicity, education, duration of illness, and substance abuse. Mean score of ROMI items corresponding to reasons for treatment adherence was greater among adherent participants, whereas the mean score of ROMI items corresponding to reasons for treatment non-adherence was greater among nonadherent participants. The ROMI item identifying that the individual believes that medications are unnecessary had the strongest influence for non-adherence (p < 0.0001). This was followed by ROMI items corresponding to no perceived daily benefit (p = 0.0008), perceived change in appearance (p = 0.0057), and perceived interference with life goals (p = 0.0033). The ROMI item identifying fear of relapse was the strongest predictor for adherence (p = 0.0017). Non-adherent patients with bipolar disorder differ from adherent patients with bipolar disorder on reasons for adherence and non-adherence. Utilization of tools that evaluate medication treatment attitudes, such as the ROMI or similar measures, may assist clinicians in the selection of interventions that are most likely to modify future treatment adherence.

The influence of geometric imperfections on the stability of three-layer beams with foam core

NASA Astrophysics Data System (ADS)

Wstawska, Iwona

2017-01-01

The main objective of this work is the numerical analysis (FE analysis) of stability of three-layer beams with metal foam core (alumina foam core). The beams were subjected to pure bending. The analysis of the local buckling was performed. Furthermore, the influence of geometric parameters of the beam and material properties of the core (linear and non-linear model) on critical loads values and buckling shape were also investigated. The calculations were made on a family of beams with different mechanical properties of the core (elastic and elastic-plastic material). In addition, the influence of geometric imperfections on deflection and normal stress values of the core and the faces has been evaluated.

Hidden Markov models for estimating animal mortality from anthropogenic hazards

EPA Science Inventory

Carcasses searches are a common method for studying the risk of anthropogenic hazards to wildlife, including non-target poisoning and collisions with anthropogenic structures. Typically, numbers of carcasses found must be corrected for scavenging rates and imperfect detection. ...

Assessing digital literacy in web-based physical activity surveillance: the WIN study.

PubMed

Mathew, Merly; Morrow, James R; Frierson, Georita M; Bain, Tyson M

2011-01-01

PURPOSE. Investigate relations between demographic characteristics and submission method, Internet or paper, when physical activity behaviors are reported. DESIGN. Observational. SETTING . Metropolitan. SUBJECTS. Adult women (N  =  918) observed weekly for 2 years (total number of weekly reports, 44,963). MEASURES. Independent variables included age, race, education, income, employment status, and Internet skills. Dependent variables were method of submission (Internet or paper) and adherence. ANALYSIS . Logistic regression to analyze weekly odds of submitting data online and meeting study adherence criteria. Model 1 investigated method of submission, model 2 analyzed meeting study's Internet adherence, and model 3 analyzed meeting total adherence regardless of submission method. RESULTS. Whites, those with good Internet skills, and those reporting higher incomes were more likely to log online. Those who were white, older, and reported good Internet skills were more likely to be at least 75% adherent online. Older women were more likely to be adherent regardless of method. Employed women were less likely to log online or be adherent. CONCLUSION . Providing participants with multiple submission methods may reduce potential bias and provide more generalizable results relevant for future Internet-based research.

How might Model-based Probabilities Extracted from Imperfect Models Guide Rational Decisions: The Case for non-probabilistic odds

NASA Astrophysics Data System (ADS)

Smith, Leonard A.

2010-05-01

This contribution concerns "deep" or "second-order" uncertainty, such as the uncertainty in our probability forecasts themselves. It asks the question: "Is it rational to take (or offer) bets using model-based probabilities as if they were objective probabilities?" If not, what alternative approaches for determining odds, perhaps non-probabilistic odds, might prove useful in practice, given the fact we know our models are imperfect? We consider the case where the aim is to provide sustainable odds: not to produce a profit but merely to rationally expect to break even in the long run. In other words, to run a quantified risk of ruin that is relatively small. Thus the cooperative insurance schemes of coastal villages provide a more appropriate parallel than a casino. A "better" probability forecast would lead to lower premiums charged and less volatile fluctuations in the cash reserves of the village. Note that the Bayesian paradigm does not constrain one to interpret model distributions as subjective probabilities, unless one believes the model to be empirically adequate for the task at hand. In geophysics, this is rarely the case. When a probability forecast is interpreted as the objective probability of an event, the odds on that event can be easily computed as one divided by the probability of the event, and one need not favour taking either side of the wager. (Here we are using "odds-for" not "odds-to", the difference being whether of not the stake is returned; odds of one to one are equivalent to odds of two for one.) The critical question is how to compute sustainable odds based on information from imperfect models. We suggest that this breaks the symmetry between the odds-on an event and the odds-against it. While a probability distribution can always be translated into odds, interpreting the odds on a set of events might result in "implied-probabilities" that sum to more than one. And/or the set of odds may be incomplete, not covering all events. We ask whether or not probabilities based on imperfect models can be expected to yield probabilistic odds which are sustainable. Evidence is provided that suggest this is not the case. Even with very good models (good in an Root-Mean-Square sense), the risk of ruin of probabilistic odds is significantly higher than might be expected. Methods for constructing model-based non-probabilistic odds which are sustainable are discussed. The aim here is to be relevant to real world decision support, and so unrealistic assumptions of equal knowledge, equal compute power, or equal access to information are to be avoided. Finally, the use of non-probabilistic odds as a method for communicating deep uncertainty (uncertainty in a probability forecast itself) is discussed in the context of other methods, such as stating one's subjective probability that the models will prove inadequate in each particular instance (that is, the Probability of a "Big Surprise").

Early detection of poor adherers to statins: applying individualized surveillance to pay for performance.

PubMed

Zimolzak, Andrew J; Spettell, Claire M; Fernandes, Joaquim; Fusaro, Vincent A; Palmer, Nathan P; Saria, Suchi; Kohane, Isaac S; Jonikas, Magdalena A; Mandl, Kenneth D

2013-01-01

Medication nonadherence costs $300 billion annually in the US. Medicare Advantage plans have a financial incentive to increase medication adherence among members because the Centers for Medicare and Medicaid Services (CMS) now awards substantive bonus payments to such plans, based in part on population adherence to chronic medications. We sought to build an individualized surveillance model that detects early which beneficiaries will fall below the CMS adherence threshold. This was a retrospective study of over 210,000 beneficiaries initiating statins, in a database of private insurance claims, from 2008-2011. A logistic regression model was constructed to use statin adherence from initiation to day 90 to predict beneficiaries who would not meet the CMS measure of proportion of days covered 0.8 or above, from day 91 to 365. The model controlled for 15 additional characteristics. In a sensitivity analysis, we varied the number of days of adherence data used for prediction. Lower adherence in the first 90 days was the strongest predictor of one-year nonadherence, with an odds ratio of 25.0 (95% confidence interval 23.7-26.5) for poor adherence at one year. The model had an area under the receiver operating characteristic curve of 0.80. Sensitivity analysis revealed that predictions of comparable accuracy could be made only 40 days after statin initiation. When members with 30-day supplies for their first statin fill had predictions made at 40 days, and members with 90-day supplies for their first fill had predictions made at 100 days, poor adherence could be predicted with 86% positive predictive value. To preserve their Medicare Star ratings, plan managers should identify or develop effective programs to improve adherence. An individualized surveillance approach can be used to target members who would most benefit, recognizing the tradeoff between improved model performance over time and the advantage of earlier detection.

Psychosocial influencers and mediators of treatment adherence in haemodialysis patients.

PubMed

Oh, Hyun Soo; Park, Ji Suk; Seo, Wha Sook

2013-09-01

This article is a report of the development and testing of the hypothetical model that illustrates relationships between treatment adherence and its psychosocial influencing factors and to elucidate the direct and indirect (mediating) effects of factors on treatment adherence. Poor adherence has been consistently reported in haemodialysis patients. Much research has showed various influencing factors of adherence, but these studies have failed to identify consistent influencing factors. This study was performed using a non-experimental, cross-sectional design. The study subjects were 150 end-stage renal failure patients on haemodialysis at a university hospital located in Incheon, South Korea. Data were collected over 10 months (June 2010-April 2011). The hypothetical model provided a good fit with data. Haemodialysis-related knowledge, perceived barrier to adherence, self-efficacy on adherence, and healthcare provider support had significant effects on adherence. Self-efficacy was found to mediate barrier-adherence and family support-adherence relationships. Self-efficacy in combination with barrier, family support, and healthcare provider support was found to mediate the depression-adherence relationship. Strategies aimed at the development of successful adherence interventions should focus on reducing perceived barriers and enhancing self-efficacy and knowledge. It can be suggested that efforts to improve the healthcare provider-patient relationship would enhance adherence. In depressive patients, strategies that promote self-efficacy and the support of family or healthcare providers could diminish the negative impact of depression on adherence. © 2013 Blackwell Publishing Ltd.

Limitations and Tolerances in Optical Devices

NASA Astrophysics Data System (ADS)

Jackman, Neil Allan

The performance of optical systems is limited by the imperfections of their components. Many of the devices in optical systems including optical fiber amplifiers, multimode transmission lines and multilayered media such as mirrors, windows and filters, are modeled by coupled line equations. This investigation includes: (i) a study of the limitations imposed on a wavelength multiplexed unidirectional ring by the non-uniformities of the gain spectra of Erbium-doped optical fiber amplifiers. We find numerical solutions for non-linear coupled power differential equations and use these solutions to compare the signal -to-noise ratios and signal levels at different nodes. (ii) An analytical study of the tolerances of imperfect multimode media which support forward traveling modes. The complex mode amplitudes are related by linear coupled differential equations. We use analytical methods to derive extended equations for the expected mode powers and give heuristic limits for their regions of validity. These results compare favorably to exact solutions found for a special case. (iii) A study of the tolerances of multilayered media in the presence of optical thickness imperfections. We use analytical methods including Kronecker producers, to calculate the reflection and transmission statistics of the media. Monte Carlo simulations compare well to our analytical method.

Justification of the estimation technique for the technical condition of the tank with inadmissible imperfections in the wall shape

NASA Astrophysics Data System (ADS)

Chepur, Petr; Tarasenko, Alexander; Gruchenkova, Alesya

2017-10-01

The paper has its focus on the problem of estimating the stress-strain state of the vertical steel tanks with the inadmissible geometric imperfections in the wall shape. In the paper, the authors refer to an actual tank to demonstrate that the use of certain design schemes can lead to the raw errors and, accordingly, to the unreliable results. Obviously, these design schemes cannot be based on when choosing the real repair technologies. For that reason, authors performed the calculations of the tank removed out of service for the repair, basing on the developed finite-element model of the VST-5000 tank with a conical roof. The proposed approach was developed for the analysis of the SSS (stress-strain state) of a tank having geometric imperfections of the wall shape. Based on the work results, the following was proposed: to amend the Annex A methodology “Method for calculating the stress-strain state of the tank wall during repair by lifting the tank and replacing the wall metal structures” by inserting the requirement to compulsory consider the actual stiffness of the VST entire structure and its roof when calculating the structure stress-strain state.

Cognitive and Behavioural Correlates of Non-Adherence to HIV Anti-Retroviral Therapy: Theoretical and Practical Insight for Clinical Psychology and Health Psychology

ERIC Educational Resources Information Center

Begley, Kim; McLaws, Mary-Louise; Ross, Michael W.; Gold, Julian

2008-01-01

This cross-sectional study identified variables associated with protease inhibitor (PI) non-adherence in 179 patients taking anti-retroviral therapy. Univariate analyses identified 11 variables associated with PI non-adherence. Multiple logistic regression modelling identified three predictors of PI non-adherence: low adherence self-efficacy and…

It's all a matter of necessity and concern: A structural equation model of adherence to antihypertensive medication.

PubMed

Wilhelm, Marcel; Rief, Winfried; Doering, Bettina K

2018-03-01

Hypertension is often treated pharmacologically, yet adherence is poor. Beliefs about antihypertensive medicine, i.e., the necessity-concern framework (NCF), are valuable for explaining adherence. Therefore, a model structure is transferred from hypercholesterolemia to hypertension, assuming a mediating role of the NCF. Patients with hypertension (n=273) were surveyed online about demographics, health- and treatment-related factors, control beliefs, necessity and concern beliefs about their medication, and adherence. The data were analyzed using structural equation modeling (SEM). Necessity was positively (β=0.26, p=0.009) and concern was negatively (β=-0.51, p=0.020) associated with adherence. The NCF mediated the influence of background variables on adherence. Necessity was associated with comorbidity (β=-0.36, p<0.001), treatment time (β=0.19, p=0.004), emotionally supportive doctor-patient communication (β=0.12, p=0.045), side effects (β=0.16, p=0.013), personal control (β=-0.13, p=0.022), and treatment control (β=0.29, p<0.001). Concern was associated with side effects (β=0.38, p<0.001) and beliefs about medicine in general being harmful (β=0.61, p<0.001). The model fit was acceptable (RMSEA=0.61). The transferred adherence model with the necessity-concern framework as a mediating factor was confirmed in hypertension, explaining more variance than previous approaches (23%). A personalized, emotionally supportive doctor-patient communication could be key to addressing beliefs about medicine and therefore to increasing adherence. Copyright © 2017 Elsevier B.V. All rights reserved.

Predictors of medication adherence in high risk youth of color living with HIV.

PubMed

Macdonell, Karen E; Naar-King, Sylvie; Murphy, Debra A; Parsons, Jeffrey T; Harper, Gary W

2010-07-01

To test predictors of medication adherence in high-risk racial or ethnic minority youth living with HIV (YLH) using a conceptual model of social cognitive predictors including a continuous measure of motivational readiness. Youth were participants in a multi-site clinical trial examining the efficacy of a motivational intervention. Racial-minority YLH (primarily African American) who were prescribed antiretroviral medication were included (N = 104). Data were collected using computer-assisted personal interviewing method via an Internet-based application and questionnaires. Using path analysis with bootstrapping, most youth reported suboptimal adherence, which predicted higher viral load. Higher motivational readiness predicted optimal adherence, and higher social support predicted readiness. Decisional balance was indirectly related to adherence. The model provided a plausible framework for understanding adherence in this population. Culturally competent interventions focused on readiness and social support may be helpful for improving adherence in YLH.

[Factors associated with adherence to school meals by adolescents in State public schools in Colombo, Paraná State, Brazil].

PubMed

Valentim, Emanuele de Araujo; Almeida, Claudia Choma Bettega de; Taconeli, César Augusto; Osório, Mônica Maria; Schmidt, Suely Teresinha

2017-10-26

This study aimed to estimate the prevalence of adherence to school meals and associated factors among adolescent schoolchildren (N = 1,569). The adolescents completed an on-line questionnaire on adherence to school meals, and their parents answered another questionnaire on socioeconomic data. The chi-square test was used to assess the association between adherence to school meals and gender, nutritional status, per capita family income, maternal schooling, adolescents' opinions on the dining hall layout, whether they considered school meals healthy, and consumption of other foods. Variables with statistical significance for adherence to school meals were included in the multilevel proportional odds logistic regression model. The covariates for comprising the final model were defined by backward selection methods. The results of the adjusted model were presented as odds ratios with respective 95% confidence intervals (95%CI). Prevalence of adherence to school meals was low, especially effective adherence (19.8%). Adherence was associated with per capita family income less than one minimum wage, lower consumption of foods outside of school meals, the fact that adolescents considered the dining hall space adequate, and believing that school meals are healthy. Adherence to school meals in this study falls short of universal coverage for the program. Different factors contribute to incomplete program implementation, which may hinder achieving the food and nutritional security policy under the Brazilian National School Feeding Program (PNAE).

Intrinsic hierarchical structural imperfections in a natural ceramic of bivalve shell with distinctly graded properties

PubMed Central

Jiao, Da; Liu, Zengqian; Zhang, Zhenjun; Zhang, Zhefeng

2015-01-01

Despite the extensive investigation on the structure of natural biological materials, insufficient attention has been paid to the structural imperfections by which the mechanical properties of synthetic materials are dominated. In this study, the structure of bivalve Saxidomus purpuratus shell has been systematically characterized quantitatively on multiple length scales from millimeter to sub-nanometer. It is revealed that hierarchical imperfections are intrinsically involved in the crossed-lamellar structure of the shell despite its periodically packed platelets. In particular, various favorable characters which are always pursued in synthetic materials, e.g. nanotwins and low-angle misorientations, have been incorporated herein. The possible contributions of these imperfections to mechanical properties are further discussed. It is suggested that the imperfections may serve as structural adaptations, rather than detrimental defects in the real sense, to help improve the mechanical properties of natural biological materials. This study may aid in understanding the optimizing strategies of structure and properties designed by nature, and accordingly, provide inspiration for the design of synthetic materials. PMID:26198844

Intrinsic hierarchical structural imperfections in a natural ceramic of bivalve shell with distinctly graded properties.

PubMed

Jiao, Da; Liu, Zengqian; Zhang, Zhenjun; Zhang, Zhefeng

2015-07-22

Despite the extensive investigation on the structure of natural biological materials, insufficient attention has been paid to the structural imperfections by which the mechanical properties of synthetic materials are dominated. In this study, the structure of bivalve Saxidomus purpuratus shell has been systematically characterized quantitatively on multiple length scales from millimeter to sub-nanometer. It is revealed that hierarchical imperfections are intrinsically involved in the crossed-lamellar structure of the shell despite its periodically packed platelets. In particular, various favorable characters which are always pursued in synthetic materials, e.g. nanotwins and low-angle misorientations, have been incorporated herein. The possible contributions of these imperfections to mechanical properties are further discussed. It is suggested that the imperfections may serve as structural adaptations, rather than detrimental defects in the real sense, to help improve the mechanical properties of natural biological materials. This study may aid in understanding the optimizing strategies of structure and properties designed by nature, and accordingly, provide inspiration for the design of synthetic materials.

Why Governments Run Schools.

ERIC Educational Resources Information Center

Brown, Byron W.

1992-01-01

Discusses problems of uncertainty and imperfect information that affect organizational choices for schools. Develops two models suggesting that schools, whether public or private, resemble each other while offering diverse curricula and outcomes. Considers the question of institutional choice by applying transaction cost economics to the options…

Psychological model of ART adherence behaviors in persons living with HIV/AIDS in Mexico: a structural equation analysis

PubMed Central

Sagarduy, José Luis Ybarra; López, Julio Alfonso Piña; Ramírez, Mónica Teresa González; Dávila, Luis Enrique Fierros

2017-01-01

ABSTRACT OBJECTIVE The objective of this study has been to test the ability of variables of a psychological model to predict antiretroviral therapy medication adherence behavior. METHODS We have conducted a cross-sectional study among 172 persons living with HIV/AIDS (PLWHA), who completed four self-administered assessments: 1) the Psychological Variables and Adherence Behaviors Questionnaire, 2) the Stress-Related Situation Scale to assess the variable of Personality, 3) The Zung Depression Scale, and 4) the Duke-UNC Functional Social Support Questionnaire. Structural equation modeling was used to construct a model to predict medication adherence behaviors. RESULTS Out of all the participants, 141 (82%) have been considered 100% adherent to antiretroviral therapy. Structural equation modeling has confirmed the direct effect that personality (decision-making and tolerance of frustration) has on motives to behave, or act accordingly, which was in turn directly related to medication adherence behaviors. In addition, these behaviors have had a direct and significant effect on viral load, as well as an indirect effect on CD4 cell count. The final model demonstrates the congruence between theory and data (x 2/df. = 1.480, goodness of fit index = 0.97, adjusted goodness of fit index = 0.94, comparative fit index = 0.98, root mean square error of approximation = 0.05), accounting for 55.7% of the variance. CONCLUSIONS The results of this study support our theoretical model as a conceptual framework for the prediction of medication adherence behaviors in persons living with HIV/AIDS. Implications for designing, implementing, and evaluating intervention programs based on the model are to be discussed. PMID:28876412

Fathers’ Involvement in Preadolescents’ Diabetes Adherence and Glycemic Control*

PubMed Central

Rohan, Jennifer M.; Carle, Adam C.; Pendley, Jennifer Shroff; Delamater, Alan; Drotar, Dennis

2011-01-01

Objective To examine the relationship of paternal involvement in diabetes care with adherence and glycemic control. Methods One hundred and thirty-six mothers and fathers of preadolescents (aged 9–12 years) with type 1 diabetes reported on paternal involvement. Adherence was measured by interview and blood glucose meter downloads. Mothers’ and fathers’ ratings of paternal involvement in diabetes care were compared. We evaluated three structural equation models linking paternal involvement with adherence and glycemic control. Results Mothers and fathers reported similar amounts of paternal involvement, yet mothers rated paternal involvement as more helpful. The data supported a model indicating links between more paternal involvement and higher HbA1c and between lower adherence and higher HbA1c. Mediation and moderation models were not supported. Discussion Although paternal involvement was not directly associated with treatment adherence, it was associated with poorer glycemic control. Some fathers may increase their involvement in response to suboptimal glycemic outcomes. PMID:21515643

An information-motivation-behavioral skills (IMB) model-based intervention for CABG patients.

PubMed

Zarani, Fariba; Besharat, Mohammad Ali; Sarami, Gholamreza; Sadeghian, Saeed

2012-12-01

In order to benefit from a coronary artery bypass graft (CABG) surgery, patients must adhere to medical recommendations and health advices. Despite the importance of adherence in CABG patients, adherence rates are disappointingly low. Despite the low adherence rates, very few articles regarding adherence-enhancing intervention among heart patients have been published. The goal of this study was to assess the effects of the Information-Motivation-Behavioral Skills (IMB) model-based intervention on the IMB model constructs among patients undergoing CABG and to evaluate the relationship of information, motivation, and behavioral skills with adherence. A total of 152 CABG patients were randomly assigned to either an intervention group or to a standard care control group. Participants completed pretest measures and were reassessed 1 month later. Findings showed mixed support for the effectiveness of the intervention. There was a significant effect of IMB intervention on information and motivation of patients, but no significant effect on behavioral skills. Furthermore, the results revealed that intervention constructs (information, motivation, and behavioral skills) were significantly related to patients' adherence. Findings provided initial evidence for the effectiveness of IMB-based interventions on the IMB constructs and supported the importance of these constructs to improve adherence; however, there are additional factors that need to be identified in order to improve behavioral skills more effectively.

An ontology for factors affecting tuberculosis treatment adherence behavior in sub-Saharan Africa.

PubMed

Ogundele, Olukunle Ayodeji; Moodley, Deshendran; Pillay, Anban W; Seebregts, Christopher J

2016-01-01

Adherence behavior is a complex phenomenon influenced by diverse personal, cultural, and socioeconomic factors that may vary between communities in different regions. Understanding the factors that influence adherence behavior is essential in predicting which individuals and communities are at risk of nonadherence. This is necessary for supporting resource allocation and intervention planning in disease control programs. Currently, there is no known concrete and unambiguous computational representation of factors that influence tuberculosis (TB) treatment adherence behavior that is useful for prediction. This study developed a computer-based conceptual model for capturing and structuring knowledge about the factors that influence TB treatment adherence behavior in sub-Saharan Africa (SSA). An extensive review of existing categorization systems in the literature was used to develop a conceptual model that captured scientific knowledge about TB adherence behavior in SSA. The model was formalized as an ontology using the web ontology language. The ontology was then evaluated for its comprehensiveness and applicability in building predictive models. The outcome of the study is a novel ontology-based approach for curating and structuring scientific knowledge of adherence behavior in patients with TB in SSA. The ontology takes an evidence-based approach by explicitly linking factors to published clinical studies. Factors are structured around five dimensions: factor type, type of effect, regional variation, cross-dependencies between factors, and treatment phase. The ontology is flexible and extendable and provides new insights into the nature of and interrelationship between factors that influence TB adherence.

An ontology for factors affecting tuberculosis treatment adherence behavior in sub-Saharan Africa

PubMed Central

Ogundele, Olukunle Ayodeji; Moodley, Deshendran; Pillay, Anban W; Seebregts, Christopher J

2016-01-01

Purpose Adherence behavior is a complex phenomenon influenced by diverse personal, cultural, and socioeconomic factors that may vary between communities in different regions. Understanding the factors that influence adherence behavior is essential in predicting which individuals and communities are at risk of nonadherence. This is necessary for supporting resource allocation and intervention planning in disease control programs. Currently, there is no known concrete and unambiguous computational representation of factors that influence tuberculosis (TB) treatment adherence behavior that is useful for prediction. This study developed a computer-based conceptual model for capturing and structuring knowledge about the factors that influence TB treatment adherence behavior in sub-Saharan Africa (SSA). Methods An extensive review of existing categorization systems in the literature was used to develop a conceptual model that captured scientific knowledge about TB adherence behavior in SSA. The model was formalized as an ontology using the web ontology language. The ontology was then evaluated for its comprehensiveness and applicability in building predictive models. Conclusion The outcome of the study is a novel ontology-based approach for curating and structuring scientific knowledge of adherence behavior in patients with TB in SSA. The ontology takes an evidence-based approach by explicitly linking factors to published clinical studies. Factors are structured around five dimensions: factor type, type of effect, regional variation, cross-dependencies between factors, and treatment phase. The ontology is flexible and extendable and provides new insights into the nature of and interrelationship between factors that influence TB adherence. PMID:27175067

A joint economic lot-sizing problem with fuzzy demand, defective items and environmental impacts

NASA Astrophysics Data System (ADS)

Jauhari, W. A.; Laksono, P. W.

2017-11-01

In this paper, a joint economic lot-sizing problem consisting of a vendor and a buyer was proposed. A buyer ordered products from a vendor to fulfill end customer’s demand. A produced a batch of products, and delivered it to the buyer. The production process in the vendor was imperfect and produced a number of defective products. Production rate was assumed to be adjustable to control the output of vendor’s production. A continuous review policy was adopted by the buyer to manage his inventory level. In addition, an average annual demand was considered to be fuzzy rather than constant. The proposed model contributed to the current inventory literature by allowing the inclusion of fuzzy annual demand, imperfect production emission cost, and adjustable production rate. The proposed model also considered carbon emission cost which was resulted from the transportation activity. A mathematical model was developed for obtaining the optimal ordering quantity, safety factor and the number of deliveries so the joint total cost was minimized. Furthermore, an iterative procedure was suggested to determine the optimal solutions.

A periodic review integrated inventory model with controllable setup cost, imperfect items, and inspection errors under service level constraint

NASA Astrophysics Data System (ADS)

Saga, R. S.; Jauhari, W. A.; Laksono, P. W.

2017-11-01

This paper presents an integrated inventory model which consists of single vendor and buyer. The buyer managed its inventory periodically and orders products from the vendor to satisfy the end customer’s demand, where the annual demand and the ordering cost were in the fuzzy environment. The buyer used a service level constraint instead of the stock-out cost term, so that the stock-out level per cycle was bounded. Then, the vendor produced and delivered products to the buyer. The vendor had a choice to commit an investment to reduce the setup cost. However, the vendor’s production process was imperfect, thus the lot delivered contained some defective products. Moreover, the buyer’s inspection process was not error-free since the inspector could be mistaken in categorizing the product’s quality. The objective was to find the optimum value for the review period, the setup cost, and the number of deliveries in one production cycle which might minimize the joint total cost. Furthermore, the algorithm and numerical example were provided to illustrate the application of the model.

The role of Patient Health Engagement Model (PHE-model) in affecting patient activation and medication adherence: A structural equation model

PubMed Central

Graffigna, Guendalina; Bonanomi, Andrea

2017-01-01

Background Increasing bodies of scientific research today examines the factors and interventions affecting patients’ ability to self-manage and adhere to treatment. Patient activation is considered the most reliable indicator of patients’ ability to manage health autonomously. Only a few studies have tried to assess the role of psychosocial factors in promoting patient activation. A more systematic modeling of the psychosocial factors explaining the variance of patient activation is needed. Objective To test the hypothesized effect of patient activation on medication adherence; to test the the hypothesized effects of positive emotions and of the quality of the patient/doctor relationship on patient activation; and to test the hypothesized mediating effect of Patient Health Engagement (PHE-model) in this pathway. Material and methods This cross-sectional study involved 352 Italian-speaking adult chronic patients. The survey included measures of i) patient activation (Patient Activation Measure 13 –short form); ii) Patient Health Engagement model (Patient Health Engagement Scale); iii) patient adherence (4 item-Morinsky Medication Adherence Scale); iv) the quality of the patients’ emotional feelings (Manikin Self Assessment Scale); v) the quality of the patient/doctor relationship (Health Care Climate Questionnaire). Structural equation modeling was used to test the hypotheses proposed. Results According to the theoretical model we hypothesized, research results confirmed that patients’ activation significantly affects their reported medication adherence. Moreover, psychosocial factors, such as the patients’ quality of the emotional feelings and the quality of the patient/doctor relationship were demonstrated to be factors affecting the level of patient activation. Finally, the mediation effect of the Patient Health Engagement model was confirmed by the analysis. Conclusions Consistently with the results of previous studies, these findings demonstrate that the Patient Health Engagement Model is a critical factor in enhancing the quality of care. The Patient Health Engagement Model might acts as a mechanism to increase patient activation and adherence. PMID:28654686

The role of Patient Health Engagement Model (PHE-model) in affecting patient activation and medication adherence: A structural equation model.

PubMed

Graffigna, Guendalina; Barello, Serena; Bonanomi, Andrea

2017-01-01

Increasing bodies of scientific research today examines the factors and interventions affecting patients' ability to self-manage and adhere to treatment. Patient activation is considered the most reliable indicator of patients' ability to manage health autonomously. Only a few studies have tried to assess the role of psychosocial factors in promoting patient activation. A more systematic modeling of the psychosocial factors explaining the variance of patient activation is needed. To test the hypothesized effect of patient activation on medication adherence; to test the the hypothesized effects of positive emotions and of the quality of the patient/doctor relationship on patient activation; and to test the hypothesized mediating effect of Patient Health Engagement (PHE-model) in this pathway. This cross-sectional study involved 352 Italian-speaking adult chronic patients. The survey included measures of i) patient activation (Patient Activation Measure 13 -short form); ii) Patient Health Engagement model (Patient Health Engagement Scale); iii) patient adherence (4 item-Morinsky Medication Adherence Scale); iv) the quality of the patients' emotional feelings (Manikin Self Assessment Scale); v) the quality of the patient/doctor relationship (Health Care Climate Questionnaire). Structural equation modeling was used to test the hypotheses proposed. According to the theoretical model we hypothesized, research results confirmed that patients' activation significantly affects their reported medication adherence. Moreover, psychosocial factors, such as the patients' quality of the emotional feelings and the quality of the patient/doctor relationship were demonstrated to be factors affecting the level of patient activation. Finally, the mediation effect of the Patient Health Engagement model was confirmed by the analysis. Consistently with the results of previous studies, these findings demonstrate that the Patient Health Engagement Model is a critical factor in enhancing the quality of care. The Patient Health Engagement Model might acts as a mechanism to increase patient activation and adherence.

Patient adherence predicts outcome from cognitive behavioral therapy in obsessive-compulsive disorder.

PubMed

Simpson, Helen Blair; Maher, Michael J; Wang, Yuanjia; Bao, Yuanyuan; Foa, Edna B; Franklin, Martin

2011-04-01

To examine the effects of patient adherence on outcome from exposure and response prevention (EX/RP) therapy in adults with obsessive-compulsive disorder (OCD). Thirty adults with OCD were randomized to EX/RP (n = 15) or EX/RP augmented by motivational interviewing strategies (n = 15). Both treatments included 3 introductory sessions and 15 exposure sessions. Because there were no significant group differences in adherence or outcome, the groups were combined to examine the effects of patient adherence on outcome. Independent evaluators assessed OCD severity using the Yale-Brown Obsessive Compulsive Scale. Therapists assessed patient adherence to between-session EX/RP assignments at each session using the Patient EX/RP Adherence Scale (PEAS). Linear regression models were used to examine the effects of PEAS scores on outcome, adjusting for baseline severity. The relationship between patient adherence and other predictors of outcome was explored using structural equation modeling. Higher average PEAS ratings significantly predicted lower posttreatment OCD severity in intent-to-treat and completer samples. PEAS ratings in early sessions (5-9) also significantly predicted posttreatment OCD severity. The effects of other significant predictors of outcome in this sample (baseline OCD severity, hoarding subtype, and working alliance) were fully mediated by patient adherence. Patient adherence to between-session EX/RP assignments significantly predicted treatment outcome, as did early patient adherence and change in early adherence. Patient adherence mediated the effects of other predictors of outcome. Future research should develop interventions that increase adherence and then test whether increasing adherence improves outcome. If effective, these interventions could then be used to personalize care. (c) 2011 APA, all rights reserved.

A structural equation model of patient-healthcare provider relationships and HIV-infected patient outcomes in Chinese populations.

PubMed

Chen, Wei-Ti; Shiu, Chengshi; Yang, Joyce P; Chuang, Peing; Zhang, Lin; Bao, Meijuan; Lu, Hongzhou

2018-03-01

Obtaining maximum antiretroviral therapy (ART) adherence is critical for maintaining a high CD4 count and strong immune function in PLWHA. Key factors for achieving optimum adherence include good medication self-efficacy, decreased medication-taking difficulties, and positive patient-healthcare provider (HCP) relationships. Limited studies have analyzed the correlation of these factors and ART adherence in Chinese population. In this paper, structural equation modeling was performed to assess the proposed model of relations between patient-HCP relationships and adherence. Audio Computer-Assisted Self-Interview (ACASI) software was used to collect data on ART adherence and patient variables among 227 PLWHA in Shanghai and Taipei. Participants completed a one-time 60-minute ACASI survey that consisted of standardized measures to assess demographics, recent CD4 counts, self-efficacy, patient-HCP relationship, adherence, and medication-taking difficulties. The data shown the relationship between patient-HCP relationships and adherence was significantly consistent with mediation by medication self-efficacy. However, patient-HCP interaction did not directly influence medication-taking difficulties, and medication-taking difficulties did not significantly affect CD4 counts. Furthermore, patient-HCP interactions did not directly impact CD4 counts; rather, the relation was consistent with mediation (by either better medication self-efficacy or better adherence) or by improved adherence alone. Future interventions should be designed to enhance self-management and provide better patient-HCP communication. This improved communication will enhance medication self-efficacy and decrease medication-taking difficulties. This in turn will improve medication adherence and immune function among PLWHA.

The Model Analyst’s Toolkit: Scientific Model Development, Analysis, and Validation

DTIC Science & Technology

2013-11-20

Granger causality F-test validation 3.1.2. Dynamic time warping for uneven temporal relationships Many causal relationships are imperfectly...mapping for dynamic feedback models Granger causality and DTW can identify causal relationships and consider complex temporal factors. However, many ...variant of the tf-idf algorithm (Manning, Raghavan, Schutze et al., 2008), typically used in search engines, to “score” features. The (-log tf) in

Reliability modelling and analysis of a multi-state element based on a dynamic Bayesian network

PubMed Central

Xu, Tingxue; Gu, Junyuan; Dong, Qi; Fu, Linyu

2018-01-01

This paper presents a quantitative reliability modelling and analysis method for multi-state elements based on a combination of the Markov process and a dynamic Bayesian network (DBN), taking perfect repair, imperfect repair and condition-based maintenance (CBM) into consideration. The Markov models of elements without repair and under CBM are established, and an absorbing set is introduced to determine the reliability of the repairable element. According to the state-transition relations between the states determined by the Markov process, a DBN model is built. In addition, its parameters for series and parallel systems, namely, conditional probability tables, can be calculated by referring to the conditional degradation probabilities. Finally, the power of a control unit in a failure model is used as an example. A dynamic fault tree (DFT) is translated into a Bayesian network model, and subsequently extended to a DBN. The results show the state probabilities of an element and the system without repair, with perfect and imperfect repair, and under CBM, with an absorbing set plotted by differential equations and verified. Through referring forward, the reliability value of the control unit is determined in different kinds of modes. Finally, weak nodes are noted in the control unit. PMID:29765629

"Development of Model-Based Air Pollution Exposure Metrics for use in Epidemiologic Studies"

EPA Science Inventory

Population-based epidemiological studies of air pollution have traditionally relied upon imperfect surrogates of personal exposures, such as area-wide ambient air pollution levels based on readily available concentrations from central monitoring sites. U.S. EPA in collaboration w...

DEVELOPMENT OF MODEL-BASED AIR POLLUTION EXPOSURE METRICS FOR USE IN EPIDEMIOLOGIC STUDIES

EPA Science Inventory

Population-based epidemiological studies of air pollution have traditionally relied upon imperfect surrogates of personal exposures, such as area-wide ambient air pollution levels based on readily available concentrations from central monitoring sites. U.S. EPA in collaboration w...

Continuous welding of unidirectional fiber reinforced thermoplastic tape material

NASA Astrophysics Data System (ADS)

Schledjewski, Ralf

2017-10-01

Continuous welding techniques like thermoplastic tape placement with in situ consolidation offer several advantages over traditional manufacturing processes like autoclave consolidation, thermoforming, etc. However, still there is a need to solve several important processing issues before it becomes a viable economic process. Intensive process analysis and optimization has been carried out in the past through experimental investigation, model definition and simulation development. Today process simulation is capable to predict resulting consolidation quality. Effects of material imperfections or process parameter variations are well known. But using this knowledge to control the process based on online process monitoring and according adaption of the process parameters is still challenging. Solving inverse problems and using methods for automated code generation allowing fast implementation of algorithms on targets are required. The paper explains the placement technique in general. Process-material-property-relationships and typical material imperfections are described. Furthermore, online monitoring techniques and how to use them for a model based process control system are presented.

Collapse of Corroded Pipelines under Combined Tension and External Pressure

PubMed Central

Ye, Hao; Yan, Sunting; Jin, Zhijiang

2016-01-01

In this work, collapse of corroded pipeline under combined external pressure and tension is investigated through numerical method. Axially uniform corrosion with symmetric imperfections is firstly considered. After verifying with existing experimental results, the finite element model is used to study the effect of tension on collapse pressure. An extensive parametric study is carried out using Python script and FORTRAN subroutine to investigate the influence of geometric parameters on the collapse behavior under combined loads. The results are used to develop an empirical equation for estimating the collapse pressure under tension. In addition, the effects of loading path, initial imperfection length, yielding anisotropy and corrosion defect length on the collapse behavior are also investigated. It is found that tension has a significant influence on collapse pressure of corroded pipelines. Loading path and anisotropic yielding are also important factors affecting the collapse behavior. For pipelines with relatively long corrosion defect, axially uniform corrosion models could be used to estimate the collapse pressure. PMID:27111544

Estimating distributions with increasing failure rate in an imperfect repair model.

PubMed

Kvam, Paul H; Singh, Harshinder; Whitaker, Lyn R

2002-03-01

A failed system is repaired minimally if after failure, it is restored to the working condition of an identical system of the same age. We extend the nonparametric maximum likelihood estimator (MLE) of a system's lifetime distribution function to test units that are known to have an increasing failure rate. Such items comprise a significant portion of working components in industry. The order-restricted MLE is shown to be consistent. Similar results hold for the Brown-Proschan imperfect repair model, which dictates that a failed component is repaired perfectly with some unknown probability, and is otherwise repaired minimally. The estimators derived are motivated and illustrated by failure data in the nuclear industry. Failure times for groups of emergency diesel generators and motor-driven pumps are analyzed using the order-restricted methods. The order-restricted estimators are consistent and show distinct differences from the ordinary MLEs. Simulation results suggest significant improvement in reliability estimation is available in many cases when component failure data exhibit the IFR property.

Security of BB84 with weak randomness and imperfect qubit encoding

NASA Astrophysics Data System (ADS)

Zhao, Liang-Yuan; Yin, Zhen-Qiang; Li, Hong-Wei; Chen, Wei; Fang, Xi; Han, Zheng-Fu; Huang, Wei

2018-03-01

The main threats for the well-known Bennett-Brassard 1984 (BB84) practical quantum key distribution (QKD) systems are that its encoding is inaccurate and measurement device may be vulnerable to particular attacks. Thus, a general physical model or security proof to tackle these loopholes simultaneously and quantitatively is highly desired. Here we give a framework on the security of BB84 when imperfect qubit encoding and vulnerability of measurement device are both considered. In our analysis, the potential attacks to measurement device are generalized by the recently proposed weak randomness model which assumes the input random numbers are partially biased depending on a hidden variable planted by an eavesdropper. And the inevitable encoding inaccuracy is also introduced here. From a fundamental view, our work reveals the potential information leakage due to encoding inaccuracy and weak randomness input. For applications, our result can be viewed as a useful tool to quantitatively evaluate the security of a practical QKD system.

An overview of state-of-the-art image restoration in electron microscopy.

PubMed

Roels, J; Aelterman, J; Luong, H Q; Lippens, S; Pižurica, A; Saeys, Y; Philips, W

2018-06-08

In Life Science research, electron microscopy (EM) is an essential tool for morphological analysis at the subcellular level as it allows for visualization at nanometer resolution. However, electron micrographs contain image degradations such as noise and blur caused by electromagnetic interference, electron counting errors, magnetic lens imperfections, electron diffraction, etc. These imperfections in raw image quality are inevitable and hamper subsequent image analysis and visualization. In an effort to mitigate these artefacts, many electron microscopy image restoration algorithms have been proposed in the last years. Most of these methods rely on generic assumptions on the image or degradations and are therefore outperformed by advanced methods that are based on more accurate models. Ideally, a method will accurately model the specific degradations that fit the physical acquisition settings. In this overview paper, we discuss different electron microscopy image degradation solutions and demonstrate that dedicated artefact regularisation results in higher quality restoration and is applicable through recently developed probabilistic methods. © 2018 The Authors Journal of Microscopy © 2018 Royal Microscopical Society.

Assessing the Multidimensional Relationship Between Medication Beliefs and Adherence in Older Adults With Hypertension Using Polynomial Regression.

PubMed

Dillon, Paul; Phillips, L Alison; Gallagher, Paul; Smith, Susan M; Stewart, Derek; Cousins, Gráinne

2018-02-05

The Necessity-Concerns Framework (NCF) is a multidimensional theory describing the relationship between patients' positive and negative evaluations of their medication which interplay to influence adherence. Most studies evaluating the NCF have failed to account for the multidimensional nature of the theory, placing the separate dimensions of medication "necessity beliefs" and "concerns" onto a single dimension (e.g., the Beliefs about Medicines Questionnaire-difference score model). To assess the multidimensional effect of patient medication beliefs (concerns and necessity beliefs) on medication adherence using polynomial regression with response surface analysis. Community-dwelling older adults >65 years (n = 1,211) presenting their own prescription for antihypertensive medication to 106 community pharmacies in the Republic of Ireland rated their concerns and necessity beliefs to antihypertensive medications at baseline and their adherence to antihypertensive medication at 12 months via structured telephone interview. Confirmatory polynomial regression found the difference-score model to be inaccurate; subsequent exploratory analysis identified a quadratic model to be the best-fitting polynomial model. Adherence was lowest among those with strong medication concerns and weak necessity beliefs, and adherence was greatest for those with weak concerns and strong necessity beliefs (slope β = -0.77, p<.001; curvature β = -0.26, p = .004). However, novel nonreciprocal effects were also observed; patients with simultaneously high concerns and necessity beliefs had lower adherence than those with simultaneously low concerns and necessity beliefs (slope β = -0.36, p = .004; curvature β = -0.25, p = .003). The difference-score model fails to account for the potential nonreciprocal effects. Results extend evidence supporting the use of polynomial regression to assess the multidimensional effect of medication beliefs on adherence.

Buckling Response of a Large-Scale, Seamless, Orthogrid-Stiffened Metallic Cylinder

NASA Technical Reports Server (NTRS)

Rudd, Michelle Tillotson; Hilburger, Mark W.; Lovejoy, Andrew E.; Lindell, Michael C.; Gardner, Nathaniel W.; Schultz, Marc R.

2018-01-01

Results from the buckling test of a compression-loaded 8-ft-diameter seamless (i.e., without manufacturing joints), orthogrid-stiffened metallic cylinder are presented. This test was used to assess the buckling response and imperfection sensitivity characteristics of a seamless cylinder. In addition, the test article and test served as a technology demonstration to show the application of the flow forming manufacturing process to build more efficient buckling-critical structures by eliminating the welded joints that are traditionally used in the manufacturing of large metallic barrels. Pretest predictions of the cylinder buckling response were obtained using a finite-element model that included measured geometric imperfections. The buckling load predicted using this model was 697,000 lb, and the test article buckled at 743,000 lb (6% higher). After the test, the model was revised to account for measured variations in skin and stiffener geometry, nonuniform loading, and material properties. The revised model predicted a buckling load of 754,000 lb, which is within 1.5% of the tested buckling load. In addition, it was determined that the load carrying capability of the seamless cylinder is approximately 28% greater than a corresponding cylinder with welded joints.

Time perspective and medication adherence among individuals with hypertension or diabetes mellitus.

PubMed

Sansbury, Brittany; Dasgupta, Abhijit; Guthrie, Lori; Ward, Michael

2014-04-01

The study determined if time perspective was associated with medication adherence among people with hypertension and diabetes. Using the Health Beliefs Model, we used path analysis to test direct and indirect effects of time perspective and health beliefs on adherence among 178 people who participated in a community-based survey near Washington, D.C. We measured three time perspectives (future, present fatalistic, and present hedonistic) with the Zimbardo Time Perspective Inventory and medication adherence by self-report. The total model demonstrated a good fit (RMSEA=0.17, 90% CI [0.10, 0.28], p=0.003; comparative fit index=0.91). Future time perspective and age showed direct effects on increased medication adherence; an increase by a single unit in future time perspective was associated with a 0.32 standard deviation increase in reported adherence. There were no significant indirect effects of time perspective with reported medication adherence through health beliefs. The findings provide the first evidence that time perspective plays an under-recognized role as a psychological motivator in medication adherence. Patient counseling for medication adherence may be enhanced if clinicians incorporate consideration of the patient's time perspective. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Quantum simulation of an ultrathin body field-effect transistor with channel imperfections

NASA Astrophysics Data System (ADS)

Vyurkov, V.; Semenikhin, I.; Filippov, S.; Orlikovsky, A.

2012-04-01

An efficient program for the all-quantum simulation of nanometer field-effect transistors is elaborated. The model is based on the Landauer-Buttiker approach. Our calculation of transmission coefficients employs a transfer-matrix technique involving the arbitrary precision (multiprecision) arithmetic to cope with evanescent modes. Modified in such way, the transfer-matrix technique turns out to be much faster in practical simulations than that of scattering-matrix. Results of the simulation demonstrate the impact of realistic channel imperfections (random charged centers and wall roughness) on transistor characteristics. The Landauer-Buttiker approach is developed to incorporate calculation of the noise at an arbitrary temperature. We also validate the ballistic Landauer-Buttiker approach for the usual situation when heavily doped contacts are indispensably included into the simulation region.

Optimal power and efficiency of quantum Stirling heat engines

NASA Astrophysics Data System (ADS)

Yin, Yong; Chen, Lingen; Wu, Feng

2017-01-01

A quantum Stirling heat engine model is established in this paper in which imperfect regeneration and heat leakage are considered. A single particle which contained in a one-dimensional infinite potential well is studied, and the system consists of countless replicas. Each particle is confined in its own potential well, whose occupation probabilities can be expressed by the thermal equilibrium Gibbs distributions. Based on the Schrödinger equation, the expressions of power output and efficiency for the engine are obtained. Effects of imperfect regeneration and heat leakage on the optimal performance are discussed. The optimal performance region and the optimal values of important parameters of the engine cycle are obtained. The results obtained can provide some guidelines for the design of a quantum Stirling heat engine.

An adherence based cost-consequence model comparing bimatoprost 0.01% to bimatoprost 0.03%.

PubMed

Wong, William B; Patel, Vaishali D; Kowalski, Jonathan W; Schwartz, Gail

2013-09-01

Estimate the long-term direct medical costs and clinical consequences of improved adherence with bimatoprost 0.01% compared to bimatoprost 0.03% in the treatment of glaucoma. A cost-consequence model was constructed from the perspective of a US healthcare payer. The model structure included three adherence levels (high, moderate, low) and four mean deviation (MD) defined health states (mild, moderate, severe glaucoma, blindness) for each adherence level. Clinical efficacy in terms of IOP reduction was obtained from the randomized controlled trial comparing bimatoprost 0.01% with bimatoprost 0.03%. Medication adherence was based on observed 12 month rates from an analysis of a nationally representative pharmacy claims database. Patients with high, moderate and low adherence were assumed to receive 100%, 50% and 0% of the IOP reduction observed in the clinical trial, respectively. Each 1 mmHg reduction in IOP was assumed to result in a 10% reduction in the risk of glaucoma progression. Worse glaucoma severity health states were associated with higher medical resource costs. Outcome measures were total costs, proportion of patients who progress and who become blind, and years of blindness. Deterministic sensitivity analyses were performed on uncertain model parameters. The percentage of patients progressing, becoming blind, and the time spent blind slightly favored bimatoprost 0.01%. Improved adherence with bimatoprost 0.01% led to higher costs in the first 2 years; however, starting in year 3 bimatoprost 0.01% became less costly compared to bimatoprost 0.03% with a total reduction in costs reaching US$3433 over a lifetime time horizon. Deterministic sensitivity analyses demonstrated that results were robust, with the majority of analyses favoring bimatoprost 0.01%. Application of 1 year adherence and efficacy over the long term are limitations. Modeling the effect of greater medication adherence with bimatoprost 0.01% compared with bimatoprost 0.03% suggests that differences may result in improved economic and patient outcomes.

Scoping review of adherence promotion theories in pelvic floor muscle training - 2011 ICS state-of-the-science seminar research paper i of iv.

PubMed

McClurg, Doreen; Frawley, Helena; Hay-Smith, Jean; Dean, Sarah; Chen, Shu-Yueh; Chiarelli, Pauline; Mair, Frances; Dumoulin, Chantale

2015-09-01

This paper, the first of four emanating from the International Continence Society's 2011 State-of-the-Science Seminar on pelvic-floor-muscle training (PFMT) adherence, aimed to summarize the literature on theoretical models to promote PFMT adherence, as identified in the research, or suggested by the seminar's expert panel, and recommends future directions for clinical practice and research. Existing literature on theories of health behavior were identified through a conventional subject search of electronic databases, reference-list checking, and input from the expert panel. A core eligibility criterion was that the study included a theoretical model to underpin adherence strategies used in an intervention to promote PFM training/exercise. A brief critique of 12 theoretical models/theories is provided and, were appropriate, their use in PFMT adherence strategies identified or examples of possible uses in future studies outlined. A better theoretical-based understanding of interventions to promote PFMT adherence through changes in health behaviors is required. The results of this scoping review and expert opinions identified several promising models. Future research should explicitly map the theories behind interventions that are thought to improve adherence in various populations (e.g., perinatal women to prevent or lessen urinary incontinence). In addition, identified behavioral theories applied to PFMT require a process whereby their impact can be evaluated. © 2015 Wiley Periodicals, Inc.

The relationship between the theory of planned behavior and medication adherence in patients with epilepsy.

PubMed

Lin, Chung-Ying; Updegraff, John A; Pakpour, Amir H

2016-08-01

The aim of this study was to apply the theory of planned behavior (TPB) with two other factors (action planning and coping planning) to the medication adherence of adults with epilepsy. We measured the elements of the theory of planned behavior (attitude, subjective norm, perceived behavioral control, and behavioral intention), action planning, and coping planning at baseline among adults with epilepsy (n=567, mean±SD age=38.37±6.71years, male=48.5%). Medication adherence was measured using the Medication Adherence Report Scale (MARS) and antiepileptic serum level at the 24-month follow-up. Structural equation modeling (SEM) examined three models relating TPB elements to medication adherence. Three SEM models all had satisfactory fit indices. Moreover, attitude, subjective norms, perceived behavioral control, and intention together explained more than 50% of the variance for medication adherence measured using MARS. The explained variance increased to 61.8% when coping planning and action planning were included in the model, with coping planning having greater association than action planning. In addition, MARS explained 3 to 5% of the objective serum level. The theory of planned behavior is useful in understanding medication adherence in adults with epilepsy, and future interventions may benefit by improving such beliefs as well as beliefs about coping planning. Copyright © 2016 Elsevier Inc. All rights reserved.

Motivation is a crucial factor for adherence to a healthy lifestyle among people with coronary heart disease after percutaneous coronary intervention.

PubMed

Kähkönen, Outi; Kankkunen, Päivi; Saaranen, Terhi; Miettinen, Heikki; Kyngäs, Helvi; Lamidi, Marja-Leena

2015-10-01

To test the Theory of Adherence of People with Chronic Disease with regard to adherence to treatment among patients with coronary heart disease after a percutaneous coronary intervention. Increased knowledge of the concept of adherence is needed for the development of nursing interventions and nursing guidelines for patients with coronary heart disease. A cross-sectional, multi-centre study. This study was conducted from February-December 2013 with 416 patients with coronary heart disease 4 months after undergoing a percutaneous coronary intervention. A self-reported questionnaire was used to assess their adherence to treatment. Data were analysed using structural equation modelling. The theory explained 45% of the adherence to a healthy lifestyle and 7% of the adherence to medication. Structural equation modelling confirmed that motivation and results of care had the highest association with adherence to a healthy lifestyle. Responsibility was associated with adherence to medication. Support from next of kin, support from nurses and physicians, and motivation, co-operation, fear of complications and a sense of normality were associated with adherence. Patients who are motivated to perform self-care and consider the results of care to be important were more likely to adhere to a healthy lifestyle. Responsible patients were more likely to adhere to their medication. It is important to account for these elements as a part of secondary prevention strategies among patients with coronary heart disease after a percutaneous coronary intervention. © 2015 John Wiley & Sons Ltd.

Bias in estimating accuracy of a binary screening test with differential disease verification

PubMed Central

Brinton, John T.; Ringham, Brandy M.; Glueck, Deborah H.

2011-01-01

SUMMARY Sensitivity, specificity, positive and negative predictive value are typically used to quantify the accuracy of a binary screening test. In some studies it may not be ethical or feasible to obtain definitive disease ascertainment for all subjects using a gold standard test. When a gold standard test cannot be used an imperfect reference test that is less than 100% sensitive and specific may be used instead. In breast cancer screening, for example, follow-up for cancer diagnosis is used as an imperfect reference test for women where it is not possible to obtain gold standard results. This incomplete ascertainment of true disease, or differential disease verification, can result in biased estimates of accuracy. In this paper, we derive the apparent accuracy values for studies subject to differential verification. We determine how the bias is affected by the accuracy of the imperfect reference test, the percent who receive the imperfect reference standard test not receiving the gold standard, the prevalence of the disease, and the correlation between the results for the screening test and the imperfect reference test. It is shown that designs with differential disease verification can yield biased estimates of accuracy. Estimates of sensitivity in cancer screening trials may be substantially biased. However, careful design decisions, including selection of the imperfect reference test, can help to minimize bias. A hypothetical breast cancer screening study is used to illustrate the problem. PMID:21495059

The Moderating Effect of Job Satisfaction on Physicians' Motivation to Adhere to Financially Incentivized Clinical Practice Guidelines.

PubMed

Waddimba, Anthony C; Beckman, Howard B; Mahoney, Thomas L; Burgess, James F

2017-04-01

We examined moderating effects of professional satisfaction on physicians' motivation to adhere to diabetes guidelines associated with pay-for-performance incentives. We merged cross-sectional survey data on attitudes, from 156 primary physicians, with prospective medical record-sourced data on guideline adherence and census data on ambulatory-care population characteristics. We examined moderating effects by testing theory-driven models for satisfied versus discontented physicians, using partial least squares structural equation modeling. Results show that attitudes motivated, while norms suppressed, adherence to guidelines among discontented physicians. Separate models for satisfied versus discontented physicians revealed motivational differences. Satisfied physicians disregarded intrinsic and extrinsic influences and biases. Discontented physicians, alienated by social pressure, favored personal inclinations. To improve adherence to guidelines among discontented physicians, incentives should align with personal attitudes and incorporate promotional campaigns countering resentment of peer and organizational pressure.

An electronic health record based model predicts statin adherence, LDL cholesterol, and cardiovascular disease in the United States Military Health System

PubMed Central

Lucas, Joseph E.; Bazemore, Taylor C.; Alo, Celan; Monahan, Patrick B.

2017-01-01

HMG-CoA reductase inhibitors (or “statins”) are important and commonly used medications to lower cholesterol and prevent cardiovascular disease. Nearly half of patients stop taking statin medications one year after they are prescribed leading to higher cholesterol, increased cardiovascular risk, and costs due to excess hospitalizations. Identifying which patients are at highest risk for not adhering to long-term statin therapy is an important step towards individualizing interventions to improve adherence. Electronic health records (EHR) are an increasingly common source of data that are challenging to analyze but have potential for generating more accurate predictions of disease risk. The aim of this study was to build an EHR based model for statin adherence and link this model to biologic and clinical outcomes in patients receiving statin therapy. We gathered EHR data from the Military Health System which maintains administrative data for active duty, retirees, and dependents of the United States armed forces military that receive health care benefits. Data were gathered from patients prescribed their first statin prescription in 2005 and 2006. Baseline billing, laboratory, and pharmacy claims data were collected from the two years leading up to the first statin prescription and summarized using non-negative matrix factorization. Follow up statin prescription refill data was used to define the adherence outcome (> 80 percent days covered). The subsequent factors to emerge from this model were then used to build cross-validated, predictive models of 1) overall disease risk using coalescent regression and 2) statin adherence (using random forest regression). The predicted statin adherence for each patient was subsequently used to correlate with cholesterol lowering and hospitalizations for cardiovascular disease during the 5 year follow up period using Cox regression. The analytical dataset included 138 731 individuals and 1840 potential baseline predictors that were reduced to 30 independent EHR “factors”. A random forest predictive model taking patient, statin prescription, predicted disease risk, and the EHR factors as potential inputs produced a cross-validated c-statistic of 0.736 for classifying statin non-adherence. The addition of the first refill to the model increased the c-statistic to 0.81. The predicted statin adherence was independently associated with greater cholesterol lowering (correlation = 0.14, p < 1e-20) and lower hospitalization for myocardial infarction, coronary artery disease, and stroke (hazard ratio = 0.84, p = 1.87E-06). Electronic health records data can be used to build a predictive model of statin adherence that also correlates with statins’ cardiovascular benefits. PMID:29155848

Adherence to Antitumor Necrosis Factor Use Recommendations in Spondyloarthritis: Measurement and Effect in the DESIR Cohort.

PubMed

Harvard, Stephanie; Guh, Daphne; Bansback, Nick; Richette, Pascal; Saraux, Alain; Fautrel, Bruno; Anis, Aslam H

2017-10-01

To evaluate a classification system to define adherence to axial spondyloarthritis (axSpA) anti-tumor necrosis factor (anti-TNF) use recommendations and examine the effect of adherence on outcomes in the DESIR cohort (Devenir des Spondylarthropathies Indifférenciées Récentes). Using alternate definitions of adherence, patients were classified as adherent "timely" anti-TNF users, nonadherent "late" anti-TNF users, adherent nonusers ("no anti-TNF need"), non-adherent nonusers ("unmet anti-TNF need"). Multivariate models were fitted to examine the effect of adherence on quality-adjusted life-years (QALY), total costs, and nonbiologic costs 1 year following an index date. Generalized linear regression models assuming a γ-distribution with log link were used for costs outcomes and linear regression models for QALY outcomes. Using the main definition of adherence, there were no significant differences between late anti-TNF users and timely anti-TNF users in total costs (RR 0.86, 95% CI 0.54-1.36, p = 0.516) or nonbiologic costs (RR 0.72, 95% CI 0.44-1.18, p = 0.187). However, in the sensitivity analysis, late anti-TNF users had significantly increased nonbiologic costs compared with timely users (RR 1.58, 95% CI 1.06-2.36, p = 0.026). In the main analysis, there were no significant differences in QALY between timely anti-TNF users and late anti-TNF users, or between timely users and patients with unmet anti-TNF need. In the sensitivity analysis, patients with unmet anti-TNF need had significantly lower QALY than timely anti-TNF users (-0.04, 95% CI -0.07 to -0.01, p = 0.016). The effect of adherence to anti-TNF recommendations on outcomes was sensitive to the definition of adherence used, highlighting the need to validate methods to measure adherence.

Interpersonal Factors Are Associated with Lower Therapist Adherence in Cognitive-Behavioural Therapy for Panic Disorder.

PubMed

Zickgraf, Hana F; Chambless, Dianne L; McCarthy, Kevin S; Gallop, Robert; Sharpless, Brian A; Milrod, Barbara L; Barber, Jacques P

2016-05-01

The contributions of disorder severity, comorbidity and interpersonal variables to therapists' adherence to a cognitive-behavioural treatment (CBT) manual were tested. Thirty-eight patients received panic control therapy (PCT) for panic disorder. Trained observers watching videotapes of the sixth session of a 24-session protocol rated therapists' adherence to PCT and their use of interventions from outside the CBT model. Different observers rated patients' behavioural resistance to therapy in the same session using the client resistance code. Interview measures obtained before treatment included the Panic Disorder Severity Scale, the anxiety disorders interview schedule for Diagnostic and Statistical Manual of Mental Disorders (DSM)-IV and the structured clinical interview for DSM-IV, Axis II. Questionnaire measures were the anxiety sensitivity index at intake, and, at session 2, the therapist and client versions of the working alliance inventory-short form. The higher the patients' resistance and the more Axis II traits a patient had, the less adherent the therapist. Moreover, the more resistant the client, the more therapists resorted to interventions from outside the CBT model. Stronger therapist and patient alliance was also generally related to better adherence, but these results were somewhat inconsistent across therapists. Pretreatment disorder severity and comorbidity were not related to adherence. Interpersonal variables, particularly behavioural resistance to therapy, are related to therapists' ability to adhere to a treatment manual and to their use of interventions from outside of the CBT model. Copyright © 2015 John Wiley & Sons, Ltd. Patients' behavioural resistance to therapy may make it more difficult for cognitive-behavioural clinicians to adhere to a structured treatment protocol and more likely for them to borrow interventions from outside the CBT model. Patients' Axis II traits may make adherence to treatment CBT protocol more difficult, although whether this is true varies across therapists. Therapists' adherence to a structured protocol and borrowing from outside of the CBT model do not appear to be affected by disorder severity or Axis I comorbidity. Copyright © 2015 John Wiley & Sons, Ltd.

Analysis of Binary Adherence Data in the Setting of Polypharmacy: A Comparison of Different Approaches

PubMed Central

Esserman, Denise A.; Moore, Charity G.; Roth, Mary T.

2009-01-01

Older community dwelling adults often take multiple medications for numerous chronic diseases. Non-adherence to these medications can have a large public health impact. Therefore, the measurement and modeling of medication adherence in the setting of polypharmacy is an important area of research. We apply a variety of different modeling techniques (standard linear regression; weighted linear regression; adjusted linear regression; naïve logistic regression; beta-binomial (BB) regression; generalized estimating equations (GEE)) to binary medication adherence data from a study in a North Carolina based population of older adults, where each medication an individual was taking was classified as adherent or non-adherent. In addition, through simulation we compare these different methods based on Type I error rates, bias, power, empirical 95% coverage, and goodness of fit. We find that estimation and inference using GEE is robust to a wide variety of scenarios and we recommend using this in the setting of polypharmacy when adherence is dichotomously measured for multiple medications per person. PMID:20414358

Factors of interpersonal communication and behavioral health on medication self-efficacy and medication adherence.

PubMed

Archiopoli, Ashley; Ginossar, Tamar; Wilcox, Bryan; Avila, Magdalena; Hill, Ricky; Oetzel, John

2016-12-01

Despite devastating effects on health outcomes and disease progression, many people living with HIV (PLWH) are non-adherent to their medications. Medication self-efficacy is a pivotal factor in medication adherence, yet its formation and relationship with other factors are understudied. This study examines a model that considers the role of three communicative factors (patient-provider communication, social support, and social undermining) and two behavioral health factors (depression and alcohol abuse) and medication self-efficacy impacting medication adherence. Methods included a cross-sectional design using a survey questionnaire of 344 PLWH. Findings indicated that 25% of variance in medication adherence can be explained by a mediation model where depression (B = -.18) and provider-patient communication (B = .21) affect medication self-efficacy, which in turn impacts medication adherence (B = .64). Other variables, including demographics, did not add any explanatory power. These findings demonstrate the complex nature of medication adherence and the formation of medication self-efficacy.

Security analysis on some experimental quantum key distribution systems with imperfect optical and electrical devices

NASA Astrophysics Data System (ADS)

Liang, Lin-Mei; Sun, Shi-Hai; Jiang, Mu-Sheng; Li, Chun-Yan

2014-10-01

In general, quantum key distribution (QKD) has been proved unconditionally secure for perfect devices due to quantum uncertainty principle, quantum noncloning theorem and quantum nondividing principle which means that a quantum cannot be divided further. However, the practical optical and electrical devices used in the system are imperfect, which can be exploited by the eavesdropper to partially or totally spy the secret key between the legitimate parties. In this article, we first briefly review the recent work on quantum hacking on some experimental QKD systems with respect to imperfect devices carried out internationally, then we will present our recent hacking works in details, including passive faraday mirror attack, partially random phase attack, wavelength-selected photon-number-splitting attack, frequency shift attack, and single-photon-detector attack. Those quantum attack reminds people to improve the security existed in practical QKD systems due to imperfect devices by simply adding countermeasure or adopting a totally different protocol such as measurement-device independent protocol to avoid quantum hacking on the imperfection of measurement devices [Lo, et al., Phys. Rev. Lett., 2012, 108: 130503].

Surface impedance and optimum surface resistance of a superconductor with an imperfect surface

NASA Astrophysics Data System (ADS)

Gurevich, Alex; Kubo, Takayuki

2017-11-01

We calculate a low-frequency surface impedance of a dirty, s -wave superconductor with an imperfect surface incorporating either a thin layer with a reduced pairing constant or a thin, proximity-coupled normal layer. Such structures model realistic surfaces of superconducting materials which can contain oxide layers, absorbed impurities, or nonstoichiometric composition. We solved the Usadel equations self-consistently and obtained spatial distributions of the order parameter and the quasiparticle density of states which then were used to calculate a low-frequency surface resistance Rs(T ) and the magnetic penetration depth λ (T ) as functions of temperature in the limit of local London electrodynamics. It is shown that the imperfect surface in a single-band s -wave superconductor results in a nonexponential temperature dependence of Z (T ) at T ≪Tc which can mimic the behavior of multiband or d -wave superconductors. The imperfect surface and the broadening of the gap peaks in the quasiparticle density of states N (ɛ ) in the bulk give rise to a weakly temperature-dependent residual surface resistance. We show that the surface resistance can be optimized and even reduced below its value for an ideal surface by engineering N (ɛ ) at the surface using pair-breaking mechanisms, particularly by incorporating a small density of magnetic impurities or by tuning the thickness and conductivity of the normal layer and its contact resistance. The results of this work address the limit of Rs in superconductors at T ≪Tc , and the ways of engineering the optimal density of states by surface nanostructuring and impurities to reduce losses in superconducting microresonators, thin-film strip lines, and radio-frequency cavities for particle accelerators.

Factors influencing adherence to psychopharmacological medications in psychiatric patients: a structural equation modeling approach.

PubMed

De Las Cuevas, Carlos; de Leon, Jose; Peñate, Wenceslao; Betancort, Moisés

2017-01-01

To evaluate pathways through which sociodemographic, clinical, attitudinal, and perceived health control variables impact psychiatric patients' adherence to psychopharmacological medications. A sample of 966 consecutive psychiatric outpatients was studied. The variables were sociodemographic (age, gender, and education), clinical (diagnoses, drug treatment, and treatment duration), attitudinal (attitudes toward psychopharmacological medication and preferences regarding participation in decision-making), perception of control over health (health locus of control, self-efficacy, and psychological reactance), and level of adherence to psychopharmacological medications. Structural equation modeling was applied to examine the nonstraightforward relationships and the interactive effects among the analyzed variables. Structural equation modeling demonstrated that psychiatric patients' treatment adherence was associated: 1) negatively with cognitive psychological reactance (adherence decreased as cognitive psychological reactance increased), 2) positively with patients' trust in their psychiatrists (doctors' subscale), 3) negatively with patients' belief that they are in control of their mental health and that their mental health depends on their own actions (internal subscale), and 4) positively (although weakly) with age. Self-efficacy indirectly influenced treatment adherence through internal health locus of control. This study provides support for the hypothesis that perceived health control variables play a relevant role in psychiatric patients' adherence to psychopharmacological medications. The findings highlight the importance of considering prospective studies of patients' psychological reactance and health locus of control as they may be clinically relevant factors contributing to adherence to psychopharmacological medications.

Explanatory Models and Medication Adherence in Patients with Depression in South India

PubMed Central

Siddappa, Adarsh Lakkur; Raman, Rajesh; Hattur, Basavana Gowdappa

2017-01-01

Introduction Conceptualization of depression may have bearing on treatment seeking. It may affect adherence behaviour of the patients. Aim To find out the explanatory models and their relationship with socio-demographic variables and medication adherence in patients with depression. Materials and Methods Fifty-eight consecutive patients with depression in remission were recruited as per selection criteria. Socio-demographic details were collected. Patients were assessed using Mental Distress Explanatory Model Questionnaire (MDEMQ) and Morisky Medication Adherence Scale (MMAS). Results Significant scores were observed in all dimensions of explanatory models. In the Mann-Whitney U test the patient’s marital status (MU=113.500, p=0.05, sig≤0.05, 2-tailed), and family history of mental illness (MU=165.5, p=0.03, sig≤0.05, 2-tailed) had a statistically significant group difference in the score of MDEMQ. In linear regression analysis, four predictors (MDEMQ subscales Stress, Western physiology, Non-Western physiology and Supernatural) had significantly predicted the value of MMAS (R2=0.937, f=153.558, p<0.001). Conclusion Findings of this study suggested that patients with depression harbor multidimensional explanatory model. The levels of explanatory models are inversely associated with levels of medication adherence. PMID:28274025

Meta-analyses of Theory use in Medication Adherence Intervention Research

PubMed Central

Conn, Vicki S.; Enriquez, Maithe; Ruppar, Todd M.; Chan, Keith C.

2016-01-01

Objective This systematic review applied meta-analytic procedures to integrate primary research that examined theory- or model-linked medication adherence interventions. Methods Extensive literature searching strategies were used to locate trials testing interventions with medication adherence behavior outcomes measured by electronic event monitoring, pharmacy refills, pill counts, and self-reports. Random-effects model analysis was used to calculate standardized mean difference effect sizes for medication adherence outcomes. Results Codable data were extracted from 146 comparisons with 19,348 participants. The most common theories and models were social cognitive theory and motivational interviewing. The overall weighted effect size for all interventions comparing treatment and control participants was 0.294. The effect size for interventions based on single-theories was 0.323 and for multiple-theory interventions was 0.214. Effect sizes for individual theories and models ranged from 0.041 to 0.447. The largest effect sizes were for interventions based on the health belief model (0.477) and adult learning theory (0.443). The smallest effect sizes were for interventions based on PRECEDE (0.041) and self-regulation (0.118). Conclusion These findings suggest that theory- and model-linked interventions have a significant but modest effect on medication adherence outcomes. PMID:26931748

The Dispersion of the Axisymmetric Longitudinal Waves in the Pre-Strained Bi-Material Hollow Cylinder with the Imperfect Interface Conditions

NASA Astrophysics Data System (ADS)

Akbarov, S. D.; Ipek, C.

This work studies the influence of the imperfectness of the interface conditions on the dispersion of the axisymmetric longitudinal waves in the pre-strained bi-material hollow cylinder. The investigations are made within the 3D linearized theory of elastic waves in elastic bodies with initial stresses. It is assumed that the materials of the layers of the hollow cylinder are made from hyper elastic compressible materials and the elasticity relations of those are given through the harmonic potential. The shear spring type imperfectness of the interface conditions is considered and the degree of this imperfectness is estimated by the shear-spring parameter. Numerical results on the influence of this parameter on the behavior of the dispersion curves are presented and discussed.

Information compression in the context model

NASA Technical Reports Server (NTRS)

Gebhardt, Joerg; Kruse, Rudolf; Nauck, Detlef

1992-01-01

The Context Model provides a formal framework for the representation, interpretation, and analysis of vague and uncertain data. The clear semantics of the underlying concepts make it feasible to compare well-known approaches to the modeling of imperfect knowledge like that given in Bayes Theory, Shafer's Evidence Theory, the Transferable Belief Model, and Possibility Theory. In this paper we present the basic ideas of the Context Model and show its applicability as an alternative foundation of Possibility Theory and the epistemic view of fuzzy sets.

Therapist adherence to a motivational-interviewing intervention improves treatment entry for substance-misusing adolescents with low problem perception.

PubMed

Smith, Douglas C; Hall, James A; Jang, Mijin; Arndt, Stephan

2009-01-01

This study evaluated whether adherence to the Strengths-Oriented Referral for Teens (SORT) model, a motivational interviewing (MI)-consistent intervention addressing ambivalence about attending treatment, positively predicted adolescents' initial-session attendance. Therapist adherence was rated in 54 audiotaped SORT sessions by coders who were blind to treatment-entry status. Higher adherence scores reflected greater use of MI and solution focused language, discussion of client strengths, and dialogue with families on treatment need and options. Therapist adherence during adolescent segments interacted with adolescent problem perception. Predicted probabilities of attending initial sessions increased for low-problem-perception adolescents at increasingly higher therapist adherence. Although replication studies are needed, the SORT model of providing MI-consistent debriefing following initial assessments appears to be a promising approach for increasing treatment entry. Initial support for the treatment-matching hypothesis was found for substance-misusing adolescents contemplating treatment entry.

Integrated multi-choice goal programming and multi-segment goal programming for supplier selection considering imperfect-quality and price-quantity discounts in a multiple sourcing environment

NASA Astrophysics Data System (ADS)

Chang, Ching-Ter; Chen, Huang-Mu; Zhuang, Zheng-Yun

2014-05-01

Supplier selection (SS) is a multi-criteria and multi-objective problem, in which multi-segment (e.g. imperfect-quality discount (IQD) and price-quantity discount (PQD)) and multi-aspiration level problems may be significantly important; however, little attention had been given to dealing with both of them simultaneously in the past. This study proposes a model for integrating multi-choice goal programming and multi-segment goal programming to solve the above-mentioned problems by providing the following main contributions: (1) it allows decision-makers to set multiple aspiration levels on the right-hand side of each goal to suit real-world situations, (2) the PQD and IQD conditions are considered in the proposed model simultaneously and (3) the proposed model can solve a SS problem with n suppliers where each supplier offers m IQD with r PQD intervals, where only ? extra binary variables are required. The usefulness of the proposed model is explained using a real case. The results indicate that the proposed model not only can deal with a SS problem with multi-segment and multi-aspiration levels, but also can help the decision-maker to find the appropriate order quantities for each supplier by considering cost, quality and delivery.

Optimization of energy window and evaluation of scatter compensation methods in MPS using the ideal observer with model mismatch

NASA Astrophysics Data System (ADS)

Ghaly, Michael; Links, Jonathan M.; Frey, Eric

2015-03-01

In this work, we used the ideal observer (IO) and IO with model mismatch (IO-MM) applied in the projection domain and an anthropomorphic Channelized Hotelling Observer (CHO) applied to reconstructed images to optimize the acquisition energy window width and evaluate various scatter compensation methods in the context of a myocardial perfusion SPECT defect detection task. The IO has perfect knowledge of the image formation process and thus reflects performance with perfect compensation for image-degrading factors. Thus, using the IO to optimize imaging systems could lead to suboptimal parameters compared to those optimized for humans interpreting SPECT images reconstructed with imperfect or no compensation. The IO-MM allows incorporating imperfect system models into the IO optimization process. We found that with near-perfect scatter compensation, the optimal energy window for the IO and CHO were similar; in its absence the IO-MM gave a better prediction of the optimal energy window for the CHO using different scatter compensation methods. These data suggest that the IO-MM may be useful for projection-domain optimization when model mismatch is significant, and that the IO is useful when followed by reconstruction with good models of the image formation process.

Modeling anuran detection and site occupancy on North American Amphibian Monitoring Program (NAAMP) routes in Maryland

USGS Publications Warehouse

Weir, L.A.; Royle, J. Andrew; Nanjappa, P.; Jung, R.E.

2005-01-01

One of the most fundamental problems in monitoring animal populations is that of imperfect detection. Although imperfect detection can be modeled, studies examining patterns in occurrence often ignore detection and thus fail to properly partition variation in detection from that of occurrence. In this study, we used anuran calling survey data collected on North American Amphibian Monitoring Program routes in eastern Maryland to investigate factors that influence detection probability and site occupancy for 10 anuran species. In 2002, 17 calling survey routes in eastern Maryland were surveyed to collect environmental and species data nine or more times. To analyze these data, we developed models incorporating detection probability and site occupancy. The results suggest that, for more than half of the 10 species, detection probabilities vary most with season (i.e., day-of-year), air temperature, time, and moon illumination, whereas site occupancy may vary by the amount of palustrine forested wetland habitat. Our results suggest anuran calling surveys should document air temperature, time of night, moon illumination, observer skill, and habitat change over time, as these factors can be important to model-adjusted estimates of site occupancy. Our study represents the first formal modeling effort aimed at developing an analytic assessment framework for NAAMP calling survey data.

Endogenous Crisis Waves: Stochastic Model with Synchronized Collective Behavior

NASA Astrophysics Data System (ADS)

Gualdi, Stanislao; Bouchaud, Jean-Philippe; Cencetti, Giulia; Tarzia, Marco; Zamponi, Francesco

2015-02-01

We propose a simple framework to understand commonly observed crisis waves in macroeconomic agent-based models, which is also relevant to a variety of other physical or biological situations where synchronization occurs. We compute exactly the phase diagram of the model and the location of the synchronization transition in parameter space. Many modifications and extensions can be studied, confirming that the synchronization transition is extremely robust against various sources of noise or imperfections.

Caution: Precision Error in Blade Alignment Results in Faulty Unsteady CFD Simulation

NASA Astrophysics Data System (ADS)

Lewis, Bryan; Cimbala, John; Wouden, Alex

2012-11-01

Turbomachinery components experience unsteady loads at several frequencies. The rotor frequency corresponds to the time for one rotor blade to rotate between two stator vanes, and is normally dominant for rotor torque oscillations. The guide vane frequency corresponds to the time for two rotor blades to pass by one guide vane. The machine frequency corresponds to the machine RPM. Oscillations at the machine frequency are always present due to minor blade misalignments and imperfections resulting from manufacturing defects. However, machine frequency oscillations should not be present in CFD simulations if the mesh is free of both blade misalignment and surface imperfections. The flow through a Francis hydroturbine was modeled with unsteady Reynolds-Averaged Navier-Stokes (URANS) CFD simulations and a dynamic rotating grid. Spectral analysis of the unsteady torque on the rotor blades revealed a large component at the machine frequency. Close examination showed that one blade was displaced by 0 .0001° due to round-off errors during mesh generation. A second mesh without blade misalignment was then created. Subsequently, large machine frequency oscillations were not observed for this mesh. These results highlight the effect of minor geometry imperfections on CFD solutions. This research was supported by a grant from the DoE and a National Defense Science and Engineering Graduate Fellowship.

Elastic and failure response of imperfect three-dimensional metallic lattices: the role of geometric defects induced by Selective Laser Melting

NASA Astrophysics Data System (ADS)

Liu, Lu; Kamm, Paul; García-Moreno, Francisco; Banhart, John; Pasini, Damiano

2017-10-01

This paper examines three-dimensional metallic lattices with regular octet and rhombicuboctahedron units fabricated with geometric imperfections via Selective Laser Sintering. We use X-ray computed tomography to capture morphology, location, and distribution of process-induced defects with the aim of studying their role in the elastic response, damage initiation, and failure evolution under quasi-static compression. Testing results from in-situ compression tomography show that each lattice exhibits a distinct failure mechanism that is governed not only by cell topology but also by geometric defects induced by additive manufacturing. Extracted from X-ray tomography images, the statistical distributions of three sets of defects, namely strut waviness, strut thickness variation, and strut oversizing, are used to develop numerical models of statistically representative lattices with imperfect geometry. Elastic and failure responses are predicted within 10% agreement from the experimental data. In addition, a computational study is presented to shed light into the relationship between the amplitude of selected defects and the reduction of elastic properties compared to their nominal values. The evolution of failure mechanisms is also explained with respect to strut oversizing, a parameter that can critically cause failure mode transitions that are not visible in defect-free lattices.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singer, B.S.; Fanini, O.; Strack, K.M.

Through casing resistivity measurements confirmed the original concept proposed by Alpin and recently revived and improved by Kaufman and Vail. A commercial tool can be used for monitoring producing wells, waterflooding control, and searching for bypassed hydrocarbons in abandoned and active wells. The information on the resistivity of the formation is represented by the second spacial derivative of the casing voltage that is generally small. This makes the evaluation of possible distortions arising from different kinds of casing imperfections important. These imperfections include casing collars, corrosion, perforations, etc. The fact that only low frequencies can be used for the measurementmore » allows us to propose fast and accurate modeling algorithms. Numerical evaluation shows that the distorting effect of casing imperfections is quite moderate. Typically, it does not exceed 10 - 20% of the measured apparent resistivity. The vertical resolution of the measurements is limited by the spacing between the voltage sensing electrodes. It can be deteriorate due to the cement sheath that always exists around the casing. A significant distortion of the measurement occurs near the bottom of the casing. This distortion can reach 50% of the signal. To improve the readings, a simplified inversion algorithm has been developed. The most direct application of the algorithm is the monitoring of the pay zone resistivity.« less

High self-efficacy predicts adherence to surveillance colonoscopy in inflammatory bowel disease.

PubMed

Friedman, Sonia; Cheifetz, Adam S; Farraye, Francis A; Banks, Peter A; Makrauer, Frederick L; Burakoff, Robert; Farmer, Barbara; Torgersen, Leanne N; Wahl, Kelly E

2014-09-01

Patients with extensive ulcerative colitis or Crohn's disease of the colon have an increased risk of colon cancer and require colonoscopic surveillance. In this study, we assessed individual self-efficacy (SE) to estimate the probability of adherence to surveillance colonoscopies. Three hundred seventy-eight patients with ulcerative colitis or Crohn's disease of the colon for at least 7 years and with at least one third of the colon involved participated in this cross-sectional questionnaire study performed at 3 tertiary referral inflammatory bowel disease clinics. Medical charts were abstracted for demographic and clinical variables. The questionnaire contained a group of items assessing SE for undergoing colonoscopy. We validated our 20-question SE scale and used 8 of the items that highlighted scheduling, preparation, and postprocedure recovery, to develop 2 shorter SE scales. All 3 scales were reliable with Cronbach's α ranging from 0.845 to 0.905 and correlated with chart-documented adherence to surveillance colonoscopy (P < 0.001). We then developed logistic regression models to predict adherence to surveillance colonoscopy using each scale separately along with other key variables (i.e., disease location, knowledge of correct adherence intervals, and information sources of patients consulted regarding Crohn's disease and ulcerative colitis) and demonstrated model accuracy up to 74%. SE, as measured by our validated scales, correlates with chart-adherence to surveillance colonoscopy. Our adherence model, which includes SE, predicts adherence with 74% certainty. An 8-item validated clinical questionnaire can be administered to assess whether patients in this population may require further intervention for adherence.

Adherence and Non-Adherence to Treatments: Focus on Pharmacy Practice in Nepal

PubMed Central

Bastakoti, Suresh; Khanal, Saval; Dahal, Bibek; Pun, Nirmala Tilija

2013-01-01

Nepal is one of the developing countries having many limitations in providing the quality health services to its population. In many countries, improvement in patients’ adherence to the pharmacotherapy had been one of major outcome of quality pharmaceutical services. Till date, very less thing has been done in this area in Nepal; so it seems mandatory to improve the patient adherence to the treatment plans. Adherence to the medical therapy can be explained by the extent of the behavioral coincidence to the medication and non-medication regimen by a patient whereas compliance and concordance are two different models of patient adherence to the therapy. Compliance model suggests that patients have been brought responsible for being unable to follow ‘doctor’s order and concordance tempts to measure the degree of agreement between patient and his or her clinician about the nature of illness and the best possible therapy for the welfare of the patient. Non-adherence to the therapy may lead to different problems as consequences of non-adherence in four different level- individual, institutional, societal and national levels. Although some programs like, “Direct Observation Treatment, Short-course (DOTS) for tuberculosis, implementation of antiretroviral treatment schedules for HIV patients and pediatric vaccination models,” are the examples of attention towards the cases of noncompliance in Nepal. It has long been faced its limitations in the forms of either untrained manpower or lack of good documentation of patients’ adherence to therapy or high illiteracy rate or unaffordibility of patients to their treatment or lack of pharmaceutical care services. PMID:23730670

Medicating the mind: a Kantian analysis of overprescribing psychoactive drugs

PubMed Central

Manninen, B A

2006-01-01

Psychoactive drugs are being prescribed to millions of Americans at an increasing rate. In many cases these drugs are necessary in order to overcome debilitating emotional problems. Yet in other instances, these drugs are used to supplant, not supplement, interpersonal therapy. The process of overcoming emotional obstacles by introspection and the attainment of self knowledge is gradually being eroded via the gratuitous use of psychoactive medication in order to rapidly attain a release from the common problems that life inevitably presents us with. In this paper, I argue that Kant's formula of humanity, which maintains that persons ought never to treat others or themselves soley as a means to an end, proscribes this. Moreover, Kant argues that we have an imperfect duty of self development, and I argue that we fail to adhere to such a duty whenever we seek to evade the process of introspection and self knowledge in favour of the expedient results that drugs may provide us with as we attempt to overcome the emotional hurdles in our lives. PMID:16446415

Psychosocial and cognitive factors associated with adherence to dietary and fluid restriction regimens by people on chronic haemodialysis.

PubMed

Sensky, T; Leger, C; Gilmour, S

1996-01-01

Failure by people on chronic haemodialysis to adhere adequately to dietary and fluid restrictions can have serious medical consequences. Numerous psychosocial factors possibly associated with adherence have been investigated in previous research. However, most previous studies have examined one or a few variables in isolation, and have tended to focus on sociodemographic variables not easily amenable to intervention. Much previous work has tended to ignore potential differences in adherence between male and female dialysands. Sociodemographic and psychosocial factors associated with adherence to dietary and fluid restrictions were investigated in 45 people on haemodialysis attending one renal unit, excluding those with a residual urine volume > 500 ml/day. Multiple regression analyses were used to estimate the contribution to adherence of a range of variables, including gender, age, duration of dialysis, affective disturbance, past psychiatric history, health locus of control, social adjustment and social supports. Adherence to diet (measured by predialysis serum potassium) and to fluid restriction (interdialysis weight gain) were not linked, and had different psychosocial correlates. Regression models of four different aspects of adherence revealed very distinct psychosocial correlates, with contributions to adherence from complex interactions between psychosocial and cognitive variables, notably gender, age, social adjustment, health locus of control, and depression. The findings cast doubt on the results of many previous studies which have used simple models of adherence. Adherence is likely to be influenced in a complex manner by multiple factors including age, gender, locus of control, social adjustment, and past psychiatric history.

Is adherence to diet, physical activity, and body weight cancer prevention recommendations associated with colorectal cancer incidence in African American women?

PubMed

Nomura, Sarah J O; Dash, Chiranjeev; Rosenberg, Lynn; Yu, Jeffrey; Palmer, Julie R; Adams-Campbell, Lucile L

2016-07-01

The purpose of this study was to evaluate whether adherence to the World Cancer Research Fund/American Institute for Cancer Research (WCRF/AICR) cancer prevention recommendations was associated with colorectal cancer incidence in the Black Women's Health Study (BWHS). In this ongoing prospective cohort of African American women (analytic cohort n = 49,103), 354 incident colorectal cancers were diagnosed between baseline (1995) and 2011. Adherence scores for seven WCRF/AICR recommendations (adherent = 1 point, non-adherent level 1 = 0.5 points, non-adherent level 2 = 0 points) were created using questionnaire data and summed to an overall adherence score (maximum = 7). Recommendation adherence and colorectal cancer incidence were evaluated using baseline and time-varying data in Cox regression models. At baseline, 8.5 % of women adhered >4 recommendations. In time-varying analyses, the HR was 0.98 (95 % CI 0.84-1.15) per 0.5 point higher score and 0.51 (95 % CI 0.23-1.10) for adherence to >4 compared to <3 recommendations. Adherence to individual recommendations was not associated with colorectal cancer risk. Results were similar in models that considered baseline exposures only. Adherence to cancer prevention recommendations was low and not associated with colorectal cancer risk among women in the BWHS. Research in diverse populations is essential to evaluate the validity of existing recommendations, and assess whether there are alternative recommendations that are more beneficial for cancer prevention in specific populations.

A continuum-based structural modeling approach for cellulose nanocrystals (CNCs)

NASA Astrophysics Data System (ADS)

Shishehbor, Mehdi; Dri, Fernando L.; Moon, Robert J.; Zavattieri, Pablo D.

2018-02-01

We present a continuum-based structural model to study the mechanical behavior of cellulose nanocrystals (CNCs), and analyze the effect of bonded and non-bonded interactions on the mechanical properties under various loading conditions. In particular, this model assumes the uncoupling between the bonded and non-bonded interactions and their behavior is obtained from atomistic simulations. Our results indicates that the major contribution to the tensile and bending stiffness is mainly due to the cellulose chain stiffness, and the shear behavior is mainly governed by Van der Waals (VdW) forces. In addition, we report a negligible torsional stiffness, which may explain the CNC tendency to easily twist under very small or nonexistent torques. In addition, the sensitivity of geometrical imperfection on the mechanical properties using an analytical model of the CNC structure was investigated. Our results indicate that the presence of imperfections have a small influence on the majority of the elastic properties. Finally, it is shown that a simple homogeneous and orthotropic representation of a CNC under bending underestimates the contribution of non-bonded interaction leading up to 60% error in the calculation of the bending stiffness of CNCs. On the other hand, the proposed model can lead to more accurate predictions of the elastic behavior of CNCs. This is the first step toward the development of a more efficient model that can be used to model the inelastic behavior of single and multiple CNCs.

Race-Based Medical Mistrust, Medication Beliefs and HIV Treatment Adherence: Test of a Mediation Model in People Living with HIV/AIDS

PubMed Central

Kalichman, Seth C.; Eaton, Lisa; Kalichman, Moira O.; Grebler, Tama; Merely, Cynthia; Welles, Brandi

2016-01-01

Race-based medical mistrust significantly predicts non-adherence to antiretroviral therapy (ART) in people living with HIV. The current study builds on previous research that shows beliefs about medication necessity (i.e., “My medicines protect me from becoming worse”) and concerns (i.e., Having to take my medicines worries me) mediate the association between race-based medical mistrust and medication adherence. Racial and ethnic minority men and women living with HIV and receiving ART (N=178) in a southern US city completed computerized measures of demographic and health characteristics, telephone interviews of race-based medical mistrust and medication beliefs, and unannounced phone-based pill counts for ART adherence. Multiple mediation modeling showed that medical mistrust is related to medication necessity and concerns beliefs and ART adherence. Furthermore, medication necessity beliefs predicted ART adherence. The indirect effect of medical mistrust on adherence through medication necessity beliefs was also significant. Results confirm that medication necessity beliefs, although not concerns beliefs, mediate the association between medical mistrust and ART adherence. Medication necessity beliefs offer a viable target for interventions to improve ART adherence in the context of mistrust that patients may have for medical providers and health care systems. PMID:27392477

Association of Antihypertensive Medication Adherence With Healthcare Use and Medicaid Expenditures for Acute Cardiovascular Events.

PubMed

Yang, Zhuo; Howard, David H; Will, Julie; Loustalot, Fleetwood; Ritchey, Matthew; Roy, Kakoli

2016-05-01

We assessed the impact of antihypertensive medication (AHM) adherence on the incidence and associated Medicaid costs of acute cardiovascular disease (CVD) events among Medicaid beneficiaries. The study cohort (n=59,037) consists of nonelderly adults continuously enrolled (36 mo and above) in a Medicaid fee-for-service program. AHM adherence was calculated using the medication possession ratio (MPR) and stratified to low (MPR<60%), moderate (60%≤MPR<80%), and high (MPR≥80%) levels. We used a proportional hazard model to estimate risk for acute CVD events and generalized linear models to estimate Medicaid per-patient-per-year costs. Low and moderate adherence subgroups had about 1.8 and 1.4 times higher risk of acute CVD events, compared with high adherence subgroup. By adherence level, Medicaid per-patient per-year costs for (1) CVD-related emergency department visits and hospitalizations were $661 (low), $479 (moderate), and $343 (high) and (2) AHMs were $430 (low), $604 (moderate), and $664 (high). Costs for CVD events and AHMs combined were similar across adherence subgroups. Lower adherence to AHM was associated with progressively higher CVD risk. The increase in medication cost from higher AHM adherence was offset solely by reduced Medicaid spending on acute CVD events.

A review of health behaviour theories: how useful are these for developing interventions to promote long-term medication adherence for TB and HIV/AIDS?

PubMed Central

Munro, Salla; Lewin, Simon; Swart, Tanya; Volmink, Jimmy

2007-01-01

Background Suboptimal treatment adherence remains a barrier to the control of many infectious diseases, including tuberculosis and HIV/AIDS, which contribute significantly to the global disease burden. However, few of the many interventions developed to address this issue explicitly draw on theories of health behaviour. Such theories could contribute to the design of more effective interventions to promote treatment adherence and to improving assessments of the transferability of these interventions across different health issues and settings. Methods This paper reviews behaviour change theories applicable to long-term treatment adherence; assesses the evidence for their effectiveness in predicting behaviour change; and examines the implications of these findings for developing strategies to improve TB and HIV/AIDS medication adherence. We searched a number of electronic databases for theories of behaviour change. Eleven theories were examined. Results Little empirical evidence was located on the effectiveness of these theories in promoting adherence. However, several models have the potential to both improve understanding of adherence behaviours and contribute to the design of more effective interventions to promote adherence to TB and HIV/AIDS medication. Conclusion Further research and analysis is needed urgently to determine which models might best improve adherence to long-term treatment regimens. PMID:17561997

Streptococcus mutans Adherence: Presumptive Evidence for Protein-Mediated Attachment Followed by Glucan-Dependent Cellular Accumulation

PubMed Central

Staat, Robert H.; Langley, Sharon D.; Doyle, R. J.

1980-01-01

Adherence of Streptococcus mutans to smooth surfaces has been attributed to the production of sucrose-derived d-glucans. However, several studies indicate that the bacterium will adhere in the absence of sucrose. The present data confirmed that S. mutans adherence to saliva-coated hydroxyapatite beads in the absence of sucrose is described by the Langmuir equation. The nature of the sucrose-independent adherence was studied with the Persea americana agglutinin as a selective adherence inhibitor. Pretreatment of the bacterium with P. americana agglutinin caused a 10-fold reduction in adherence, and the inhibition was not reversed with the addition of sucrose. Pretreatment of S. mutans with proteases also reduced adherence, regardless of the sucrose content, whereas periodate oxidation and glucanohydrolase treatment of the bacteria reduced sucrose-mediated adherence to the levels found for sucrose-independent adherence. The P. americana agglutinin, glucanohydrolase, and pepsin pretreatment of the cells did not eliminate sucrose-induced agglutination. Scanning electron microscopy showed that short streptococcal chains were bound to saliva-coated hydroxyapatite crystals in the sucrose-independent system, whereas the presence of sucrose caused larger bacterial clumps to be found. A two-reaction model of S. mutans adherence was developed from these data. It is proposed that one reaction is attachment to the tooth pellicle which is mediated by cell-surface proteins rather than glucans or teichoic acids. The other reaction is cellular accumulation mediated by sucrose-derived d-glucans and cell surface lectins. A series of sequential adherence experiments with P. americana agglutinin as a selective inhibitor provided presumptive evidence for the validity of our model of S. mutans adherence. Images Fig. 1 PMID:7380545

Challenging an Idea Whose Time Has Gone

ERIC Educational Resources Information Center

Cross, Tracy L.; Cross, Jennifer Riedl

2017-01-01

In this response to Sternberg's article, "ACCEL: A New Model for Identifying the Gifted," we agree that IQ testing may have outlasted its usefulness as an identification tool for gifted students. The field's commitment to an imperfect formula has neglected the evolution of offerings in schools and theoretical underpinnings that are…

Algorithm for the Evaluation of Imperfections in Auto Bodywork Using Profiles from a Retroreflective Image

PubMed Central

Barber, Ramon; Zwilling, Valerie; Salichs, Miguel A.

2014-01-01

Nowadays the automobile industry is becoming more and more demanding as far as quality is concerned. Within the wide variety of processes in which this quality must be ensured, those regarding the squeezing of the auto bodywork are especially important due to the fact that the quality of the resulting product is tested manually by experts, leading to inaccuracies of all types. In this paper, an algorithm is proposed for the automated evaluation of the imperfections in the sheets of the bodywork after the squeezing process. The algorithm processes the profile signals from a retroreflective image and characterizes an imperfection. It is based on a convergence criterion that follows the line of the maximum gradient of the imperfection and gives its geometrical characteristics as a result: maximum gradient, length, width, and area. PMID:24504105

Algorithm for the evaluation of imperfections in auto bodywork using profiles from a retroreflective image.

PubMed

Barber, Ramon; Zwilling, Valerie; Salichs, Miguel A

2014-02-05

Nowadays the automobile industry is becoming more and more demanding as far as quality is concerned. Within the wide variety of processes in which this quality must be ensured, those regarding the squeezing of the auto bodywork are especially important due to the fact that the quality of the resulting product is tested manually by experts, leading to inaccuracies of all types. In this paper, an algorithm is proposed for the automated evaluation of the imperfections in the sheets of the bodywork after the squeezing process. The algorithm processes the profile signals from a retroreflective image and characterizes an imperfection. It is based on a convergence criterion that follows the line of the maximum gradient of the imperfection and gives its geometrical characteristics as a result: maximum gradient, length, width, and area.

Dynamic imperfections and optimized feedback design in the Compact Linear Collider main linac

NASA Astrophysics Data System (ADS)

Eliasson, Peder

2008-05-01

The Compact Linear Collider (CLIC) main linac is sensitive to dynamic imperfections such as element jitter, injected beam jitter, and ground motion. These effects cause emittance growth that, in case of ground motion, has to be counteracted by a trajectory feedback system. The feedback system itself will, due to jitter effects and imperfect beam position monitors (BPMs), indirectly cause emittance growth. Fast and accurate simulations of both the direct and indirect effects are desirable, but due to the many elements of the CLIC main linac, simulations may become very time consuming. In this paper, an efficient way of simulating linear (or nearly linear) dynamic effects is described. The method is also shown to facilitate the analytic determination of emittance growth caused by the different dynamic imperfections while using a trajectory feedback system. Emittance growth expressions are derived for quadrupole, accelerating structure, and beam jitter, for ground motion, and for noise in the feedback BPMs. Finally, it is shown how the method can be used to design a feedback system that is optimized for the optics of the machine and the ground motion spectrum of the particular site. This feedback system gives an emittance growth rate that is approximately 10 times lower than that of traditional trajectory feedbacks. The robustness of the optimized feedback system is studied for a number of additional imperfections, e.g., dipole corrector imperfections and faulty knowledge about the machine optics, with promising results.

Persistent agents in Axelrod's social dynamics model

NASA Astrophysics Data System (ADS)

Reia, Sandro M.; Neves, Ubiraci P. C.

2016-01-01

Axelrod's model of social dynamics has been studied under the effect of external media. Here we study the formation of cultural domains in the model by introducing persistent agents. These are agents whose cultural traits are not allowed to change but may be spread through local neighborhood. In the absence of persistent agents, the system is known to present a transition from a monocultural to a multicultural regime at some critical Q (number of traits). Our results reveal a dependence of critical Q on the occupation probability p of persistent agents and we obtain the phase diagram of the model in the (p,Q) -plane. The critical locus is explained by the competition of two opposite forces named here barrier and bonding effects. Such forces are verified to be caused by non-persistent agents which adhere (adherent agents) to the set of traits of persistent ones. The adherence (concentration of adherent agents) as a function of p is found to decay for constant Q. Furthermore, adherence as a function of Q is found to decay as a power law with constant p.

Antiretroviral drug diversion links social vulnerability to poor medication adherence in substance abusing populations.

PubMed

Tsuyuki, Kiyomi; Surratt, Hilary L

2015-05-01

Antiretroviral (ARV) medication diversion to the illicit market has been documented in South Florida, and linked to sub-optimal adherence in people living with HIV. ARV diversion reflects an unmet need for care in vulnerable populations that have difficulty engaging in consistent HIV care due to competing needs and co-morbidities. This study applies the Gelberg-Andersen behavioral model of health care utilization for vulnerable populations to understand how social vulnerability is linked to ARV diversion and adherence. Cross-sectional data were collected from a targeted sample of vulnerable people living with HIV in South Florida between 2010 and 2012 (n = 503). Structured interviews collected quantitative data on ARV diversion, access and utilization of care, and ARV adherence. Logistic regression was used to estimate the goodness-of-fit of additive models that test domain fit. Linear regression was used to estimate the effects of social vulnerability and ARV diversion on ARV adherence. The best fitting model to predict ARV diversion identifies having a low monthly income and unstable HIV care as salient enabling factors that promote ARV diversion. Importantly, health care need factors did not protect against ARV diversion, evidence that immediate competing needs are prioritized even in the face of poor health for this sample. We also find that ARV diversion provides a link between social vulnerability and sub-optimal ARV adherence, with ARV diversion and domains from the Behavioral Model explaining 25 % of the variation in ARV adherence. Our analyses reveal great need to improve engagement in HIV care for vulnerable populations by strengthening enabling factors (e.g. patient-provider relationship) to improve retention in HIV care and ARV adherence for vulnerable populations.

A Model of Parental Distress and Factors that Mediate its Link with Parental Monitoring of Youth Diabetes Care, Adherence, and Glycemic Control

PubMed Central

Robinson, Elizabeth M.; Weaver, Patrick; Chen, Rusan; Streisand, Randi; Holmes, Clarissa S.

2016-01-01

Objective Parental monitoring of adolescents’ diabetes self-care is associated with better adherence and glycemic control (A1c). A number of parent-level factors are associated with higher levels of parental monitoring, including lower levels of parental distress (depressive symptoms, stress, anxiety), as well as higher levels of parental self-efficacy for diabetes management and authoritative parenting. Often studied in isolation, these factors may be best considered simultaneously as they are interrelated and are associated with parental monitoring and youth adherence. Methods Structural equation modeling with a cross-sectional sample of 257 parent/youth (aged 11-14) dyads: 1) examined a broad model of parental factors (i.e., parental distress, parental diabetes self-efficacy, authoritative parenting) and 2) assessed their relation to parental monitoring, youth adherence, and A1c. Post-hoc ANOVAs evaluated clinical implications of daily parental monitoring. Results Parental distress was not related directly to parental monitoring. Instead less distress related indirectly to more monitoring via higher parental self-efficacy and more authoritative parenting which in turn related to better adherence and A1c. Higher parental self-efficacy also related directly to better youth adherence and then to better A1c. Clinically, more parental monitoring related to more daily blood glucose checks and to better A1c (8.48% v. 9.17%). Conclusions A broad model of parent-level factors revealed more parental distress was linked only indirectly to less monitoring via lower parental self-efficacy and less authoritative parenting. Behaviorally, more parental monitoring related to better adherence and to clinically better A1c in adolescents. Further study of parent-level factors that relate to parental distress and monitoring of adherence appears warranted. PMID:27513476

Influence of minor geometric features on Stirling pulse tube cryocooler performance

NASA Astrophysics Data System (ADS)

Fang, T.; Spoor, P. S.; Ghiaasiaan, S. M.; Perrella, M.

2017-12-01

Minor geometric features and imperfections are commonly introduced into the basic design of multi-component systems to simplify or reduce the manufacturing expense. In this work, the cooling performance of a Stirling type cryocooler was tested in different driving powers, cold-end temperatures and inclination angles. A series of Computational Fluid Dynamics (CFD) simulations based on a prototypical cold tip was carried out. Detailed CFD model predictions were compared with the experiment and were used to investigate the impact of such apparently minor geometric imperfections on the performance of Stirling type pulse tube cryocoolers. Predictions of cooling performance and gravity orientation sensitivity were compared with experimental results obtained with the cryocooler prototypes. The results indicate that minor geometry features in the cold tip assembly can have considerable negative effects on the gravity orientation sensitivity of a pulse tube cryocooler.

Racial differences in virologic failure associated with adherence and quality of life on efavirenz-containing regimens for initial HIV therapy: results of ACTG A5095.

PubMed

Schackman, Bruce R; Ribaudo, Heather J; Krambrink, Amy; Hughes, Valery; Kuritzkes, Daniel R; Gulick, Roy M

2007-12-15

Blacks had higher rates of virologic failure than whites on efavirenz-containing regimens in the AIDS Clinical Trials Group (ACTG) A5095 study; preliminary analyses also suggested an association with adherence. We rigorously examined associations over time among race, virologic failure, 4 self-reported adherence metrics, and quality of life (QOL). ACTG A5095 was a double-blind placebo-controlled study of treatment-naive HIV-positive patients randomized to zidovudine/lamivudine/abacavir versus zidovudine/lamivudine plus efavirenz versus zidovudine/lamivudine/abacavir plus efavirenz. Virologic failure was defined as confirmed HIV-1 RNA >or=200 copies/mL at >or=16 weeks on study. The zidovudine/lamivudine/abacavir arm was discontinued early because of virologic inferiority. We examined virologic failure differences for efavirenz-containing arms according to missing 0 (adherent) versus at least 1 dose (nonadherent) during the past 4 days, alternative self-reported adherence metrics, and QOL. Analyses used the Fisher exact, log rank tests, and Cox proportional hazards models. The study population included white (n = 299), black (n = 260), and Hispanic (n = 156) patients with >or=1 adherence evaluation. Virologic failure was associated with week 12 nonadherence during the past 4 days for blacks (53% nonadherent failed vs. 25% adherent; P < 0.001) but not for whites (20% nonadherent failed vs. 20% adherent; P = 0.91). After adjustment for baseline covariates and treatment, there was a significant interaction between race and week 12 adherence (P = 0.02). In time-dependent Cox models using self-reports over time to reflect recent adherence, there was a significantly higher failure risk for nonadherent subjects (hazard ratio [HR] = 2.07; P < 0.001). Significant race-adherence interactions were seen in additional models of adherence: missing at least 1 medication dose ever (P = 0.04), past month (P < 0.01), or past weekend (P = 0.05). Lower QOL was significantly associated with virologic failure (P < 0.001); there was no evidence of an interaction between QOL and race (P = 0.39) or adherence (P = 0.51) in predicting virologic failure. There was a greater effect of nonadherence on virologic failure in blacks given efavirenz-containing regimens than in whites. Self-reported adherence and QOL are independent predictors of virologic failure.

Cross-layer Design for MIMO Systems with Transmit Antenna Selection and Imperfect CSI

NASA Astrophysics Data System (ADS)

Yu, Xiangbin; Liu, Yan; Rui, Yun; Zhou, Tingting; Yin, Xin

2013-04-01

In this paper, by combining adaptive modulation and automatic repeat request (ARQ), a cross-layer design (CLD) scheme for multiple-input and multiple-output (MIMO) system with transmit antenna selection (TAS) and imperfect channel state information (CSI) is presented. Based on the imperfect CSI, the probability density function of the effective signal to noise ratio (SNR) is derived, and the fading gain switching thresholds are also derived subject to a target packet loss rate and fixed power constraint. According to these results, we further derive the average spectrum efficiency (SE) and packet error rate (PER) of the system. As a result, closed-form expressions of the average SE and PER are obtained, respectively. The derived expressions include the expressions under perfect CSI as special cases, and can provide good performance evaluation for the CLD system with imperfect CSI. Simulation results verify the validity of the theoretical analysis. The results show that the CLD system with TAS provides better SE than that with space-time block coding, but the SE and PER performance of the system with imperfect CSI are worse than those with perfect CSI due to the estimation error.

Evaluation of a Highly Anticlastic Panel with Tow Overlaps

NASA Technical Reports Server (NTRS)

Wu, K. Chauncey; Gurdal, Zafer

2007-01-01

A rectangular, variable-stiffness panel with tow overlaps was manufactured using an advanced tow placement machine. The cured panel had large anticlastic imperfections, with measured amplitudes of over two times the average panel thickness. These imperfections were not due to the overall steered-fiber layup or the tow overlaps, but instead resulted from local asymmetries in the laminate that were caused by a manufacturing oversight. In the nominal panel layup, fiber angles vary linearly from 60 degrees on the panel axial centerline to 30 degrees on the parallel edges. A geometrically nonlinear analysis was performed with a -280 degree Fahrenheit thermal load to simulate the postcure cooldown to room temperature. The predicted geometric imperfections correlated well with the measured panel shape. Unique structural test fixtures were then developed which greatly reduced these imperfections, but they also caused prestresses in the panel. Surface imperfections measured after the panel was installed in the test fixtures were used with nonlinear finite element analyses to predict these fixturing-induced prestresses. These prestresses were also included in structural analyses of panel end compression to failure, and the analytical results compared well with test data when both geometric and material nonlinearities were included.

Common Dyadic Coping Is Indirectly Related to Dietary and Exercise Adherence via Patient and Partner Diabetes Efficacy

PubMed Central

Johnson, Matthew D.; Anderson, Jared R.; Walker, Ann; Wilcox, Allison; Lewis, Virginia L.; Robbins, David C.

2014-01-01

Using cross-sectional data from 117 married couples in which one member is diagnosed with type 2 diabetes, the current study sought to explore a possible indirect association between common dyadic coping and dietary and exercise adherence via the mechanism of patient and spouse reports of diabetes efficacy. Results from the structural equation model analysis indicated common dyadic coping was associated with higher levels of diabetes efficacy for both patients and spouses which, in turn, was then associated with better dietary and exercise adherence for the patient. This model proved a better fit to the data than three plausible alternative models. The bootstrap test of mediation revealed common dyadic coping was indirectly associated with dietary adherence via both patient and spouse diabetes efficacy, but spouse diabetes efficacy was the only mechanism linking common dyadic coping and exercise adherence. This study highlights the importance of exploring the indirect pathways through which general intimate relationship functioning might be associated with type 2 diabetes outcomes. PMID:24015707

Improving imperfect data from health management information systems in Africa using space-time geostatistics.

PubMed

Gething, Peter W; Noor, Abdisalan M; Gikandi, Priscilla W; Ogara, Esther A A; Hay, Simon I; Nixon, Mark S; Snow, Robert W; Atkinson, Peter M

2006-06-01

Reliable and timely information on disease-specific treatment burdens within a health system is critical for the planning and monitoring of service provision. Health management information systems (HMIS) exist to address this need at national scales across Africa but are failing to deliver adequate data because of widespread underreporting by health facilities. Faced with this inadequacy, vital public health decisions often rely on crudely adjusted regional and national estimates of treatment burdens. This study has taken the example of presumed malaria in outpatients within the largely incomplete Kenyan HMIS database and has defined a geostatistical modelling framework that can predict values for all data that are missing through space and time. The resulting complete set can then be used to define treatment burdens for presumed malaria at any level of spatial and temporal aggregation. Validation of the model has shown that these burdens are quantified to an acceptable level of accuracy at the district, provincial, and national scale. The modelling framework presented here provides, to our knowledge for the first time, reliable information from imperfect HMIS data to support evidence-based decision-making at national and sub-national levels.

Nonlocal postbuckling analysis of graphene sheets with initial imperfection based on first order shear deformation theory

NASA Astrophysics Data System (ADS)

Soleimani, Ahmad; Naei, Mohammad Hasan; Mashhadi, Mahmoud Mosavi

In this paper, the first order shear deformation theory (FSDT) is used to investigate the postbuckling behavior of orthotropic single-layered graphene sheet (SLGS) under in-plane loadings. Nonlocal elasticity theory and von-Karman nonlinear model in combination with the isogeometric analysis (IGA) have been applied to study the postbuckling characteristics of SLGSs. In contrast to the classical model, the nonlocal continuum model developed in this work considers the size-effects on the postbuckling characteristics of SLGSs. FSDT takes into account effects of shear deformations through-the-thickness of plate. Geometric imperfection which is defined as a very small transverse displacement of the mid-plane is applied on undeformed nanoplate to create initial deviation in graphene sheet from being perfectly flat. Nonlinear governing equations of motion for SLGS are derived from the principle of virtual work and a variational formulation. At the end, the results are presented as the postbuckling equilibrium paths of SLGS. The influence of various parameters such as edge length, nonlocal parameter, compression ratio, boundary conditions and aspect ratio on the postbuckling path is investigated. The results of this work show the high accuracy of nonlocal FSDT-based analysis for postbuckling behavior of graphene sheets.

Improved HDRG decoders for qudit and non-Abelian quantum error correction

NASA Astrophysics Data System (ADS)

Hutter, Adrian; Loss, Daniel; Wootton, James R.

2015-03-01

Hard-decision renormalization group (HDRG) decoders are an important class of decoding algorithms for topological quantum error correction. Due to their versatility, they have been used to decode systems with fractal logical operators, color codes, qudit topological codes, and non-Abelian systems. In this work, we develop a method of performing HDRG decoding which combines strengths of existing decoders and further improves upon them. In particular, we increase the minimal number of errors necessary for a logical error in a system of linear size L from \\Theta ({{L}2/3}) to Ω ({{L}1-ε }) for any ε \\gt 0. We apply our algorithm to decoding D({{{Z}}d}) quantum double models and a non-Abelian anyon model with Fibonacci-like fusion rules, and show that it indeed significantly outperforms previous HDRG decoders. Furthermore, we provide the first study of continuous error correction with imperfect syndrome measurements for the D({{{Z}}d}) quantum double models. The parallelized runtime of our algorithm is poly(log L) for the perfect measurement case. In the continuous case with imperfect syndrome measurements, the averaged runtime is O(1) for Abelian systems, while continuous error correction for non-Abelian anyons stays an open problem.

Improving Imperfect Data from Health Management Information Systems in Africa Using Space–Time Geostatistics

PubMed Central

Gething, Peter W; Noor, Abdisalan M; Gikandi, Priscilla W; Ogara, Esther A. A; Hay, Simon I; Nixon, Mark S; Snow, Robert W; Atkinson, Peter M

2006-01-01

Background Reliable and timely information on disease-specific treatment burdens within a health system is critical for the planning and monitoring of service provision. Health management information systems (HMIS) exist to address this need at national scales across Africa but are failing to deliver adequate data because of widespread underreporting by health facilities. Faced with this inadequacy, vital public health decisions often rely on crudely adjusted regional and national estimates of treatment burdens. Methods and Findings This study has taken the example of presumed malaria in outpatients within the largely incomplete Kenyan HMIS database and has defined a geostatistical modelling framework that can predict values for all data that are missing through space and time. The resulting complete set can then be used to define treatment burdens for presumed malaria at any level of spatial and temporal aggregation. Validation of the model has shown that these burdens are quantified to an acceptable level of accuracy at the district, provincial, and national scale. Conclusions The modelling framework presented here provides, to our knowledge for the first time, reliable information from imperfect HMIS data to support evidence-based decision-making at national and sub-national levels. PMID:16719557

Evaluating Fidelity: Predictive Validity for a Measure of Competent Adherence to the Oregon Model of Parent Management Training

PubMed Central

Forgatch, Marion S.; Patterson, Gerald R.; DeGarmo, David S.

2006-01-01

When efficacious interventions are implemented in real-world conditions, it is important to evaluate whether or not the programs are practiced as intended. This article presents the Fidelity of Implementation Rating System (FIMP), an observation-based measure assessing competent adherence to the Oregon model of Parent Management Training (PMTO). FIMP evaluates 5 dimensions of competent adherence to PMTO (i.e., knowledge, structure, teaching skill, clinical skill, and overall effectiveness) specified in the intervention model. Predictive validity for FIMP was evaluated with a subsample of stepfamilies participating in a preventive PMTO intervention. As hypothesized, high FIMP ratings predicted change in observed parenting practices from baseline to 12 months. The rigor and scope of adherence measures are discussed. PMID:16718302

Psychological and Educational Intervention to Improve Tuberculosis Treatment Adherence in Ethiopia Based on Health Belief Model: A Cluster Randomized Control Trial.

PubMed

Tola, Habteyes Hailu; Shojaeizadeh, Davoud; Tol, Azar; Garmaroudi, Gholamreza; Yekaninejad, Mir Saeed; Kebede, Abebaw; Ejeta, Luche Tadesse; Kassa, Desta; Klinkenberg, Eveline

2016-01-01

Treatment non-adherence results in treatment failure, prolonged transmission of disease and emergence of drug resistance. Although the problem widely investigated, there remains an information gap on the effectiveness of different methods to improve treatment adherence and the predictors of non-adherence in resource limited countries based on theoretical models. This study aimed to evaluate the impact of psychological counseling and educational intervention on tuberculosis (TB) treatment adherence based on Health Belief Model (HBM). A cluster randomized control trial was conducted in Addis Ababa from May to December, 2014. Patients were enrolled into study consecutively from 30 randomly selected Health Centers (HCs) (14 HCs intervention and 16 HCs control groups). A total of 698 TB patients, who were on treatment for one month to two months were enrolled. A structured questionnaire was administered to both groups of patients at baseline and endpoint of study. Control participants received routine directly-observed anti-TB therapy and the intervention group additionally received combined psychological counseling and adherence education. Treatment non-adherence level was the main outcome of the study, and multilevel logistic regression was employed to assess the impact of intervention on treatment adherence. At enrollment, the level of non-adherence among intervention (19.4%) and control (19.6%) groups was almost the same. However, after intervention, non-adherence level decreased among intervention group from 19.4 (at baseline) to 9.5% (at endpoint), while it increased among control group from 19.4% (baseline) to 25.4% (endpoint). Psychological counseling and educational interventions resulted in significant difference with regard to non-adherence level between intervention and control groups (Adjusted OR = 0.31, 95% Confidence Interval (CI) (0.18-0.53), p < 0.001)). Psychological counseling and educational interventions, which were guided by HBM, significantly decreased treatment non-adherence level among intervention group. Provision of psychological counseling and health education to TB patients who are on regular treatment is recommended. This could be best achieved if these interventions are guided by behavioral theories and incorporated into the routine TB treatment strategy. Pan African Clinical Trials Registry PACTR201506001175423.

Female sexual function mediates the effects of medication adherence on quality of life in people with epilepsy.

PubMed

Lin, Chung-Ying; Burri, Andrea; Fridlund, Bengt; Pakpour, Amir H

2017-02-01

The purpose of this study was to understand the mediating effects of female sexual functioning in the association between medication adherence and quality of life (QoL) in Iranian women with epilepsy (WWE). Women's sexual functioning was measured using Female Sexual Function Index; QoL using Quality of Life in Epilepsy; epilepsy severity using Liverpool Seizure Severity Scale; subjective medication adherence using Medication Adherence Report Scale; and objective medication adherence using serum level for antiepileptic drugs in 567 WWE. Medication adherence was measured at baseline, while women's sexual functioning, QoL, and epilepsy severity were measured at the 6-month follow-up. Structural equation modeling and regression models were conducted to examine the mediating role of women's sexual functioning. The mediating effects of sexual functioning in the relationship between medication adherence (including subjective and objective measures) and QoL were supported in the total score of Female Sexual Function Index (coefficient=0.415, SE=0.117, p<0.001 for subjective medication adherence; coefficient=1.980, SE=0.446, p<0.001 for objective medication adherence). Seizure severity was significantly associated with QoL but only when objective medication adherence was measured (coefficient=-0.094, SE=0.036, p=0.009). Our results extended the importance of medication adherence from symptom reduction to the beneficial effects of women's sexual functioning and QoL. Health care providers should be aware of these additional benefits of medication adherence and use these arguments to encourage female patients to take their medication, which can eventually increase their sexual satisfaction and overall QoL. Copyright © 2016 Elsevier Inc. All rights reserved.

A Longitudinal Analysis of Daily Pill Burden and Likelihood of Optimal Adherence to Antiretroviral Therapy Among People Living With HIV Who Use Drugs.

PubMed

Mohd Salleh, Nur Afiqah; Richardson, Lindsey; Kerr, Thomas; Shoveller, Jean; Montaner, Julio; Kamarulzaman, Adeeba; Milloy, M-J

2018-03-07

Among people living with HIV (PLWH), high levels of adherence to prescribed antiretroviral therapy (ART) is required to achieve optimal treatment outcomes. However, little is known about the effects of daily pill burden on adherence amongst PLWH who use drugs. We sought to investigate the association between daily pill burden and adherence to ART among members of this key population in Vancouver, Canada. We used data from the AIDS Care Cohort to Evaluate Exposure to Survival Services study, a long-running community-recruited cohort of PLWH who use illicit drugs linked to comprehensive HIV clinical records. The longitudinal relationship between daily pill burden and the odds of ≥95% adherence to ART among ART-exposed individuals was analyzed using multivariable generalized linear mixed-effects modeling, adjusting for sociodemographic, behavioural, and structural factors linked to adherence. Between December 2005 and May 2014, the study enrolled 770 ART-exposed participants, including 257 (34%) women, with a median age of 43 years. At baseline, 437 (56.7%) participants achieved ≥95% adherence in the previous 180 days. Among all interview periods, the median adherence was 100% (interquartile range 71%-100%). In a multivariable model, a greater number of pills per day was negatively associated with ≥95% adherence (adjusted odds ratio [AOR] 0.87 per pill, 95% confidence interval [CI] 0.84-0.91). Further analysis showed that once-a-day ART regimens were positively associated with optimal adherence (AOR 1.39, 95% CI 1.07-1.80). In conclusion, simpler dosing demands (ie, fewer pills and once-a-day single tablet regimens) promoted optimal adherence among PLWH who use drugs. Our findings highlight the need for simpler dosing to be encouraged explicitly for PWUD with multiple adherence barriers.

[Study of an adherence rating score system for tuberculosis patients in China].

PubMed

Yuan, Yan-li; Yu, Bao-zhu; Jiang, Shi-wen; Wang, Tao; Lv, Jun; Tao, Qiu-Shan

2010-06-18

To develop an adherence rating score (ARS) system specific for tuberculosis (TB) patients. A cross-sectional survey of 124 TB patients was conducted to figure out risk factors for adherence to treatment. The step-wise logistic regression models were used for selecting adherence-related variables. ARS was developed based on the weighting scores of the parameters of all the predicted variables in the logistic model. The reliability and responsibility of ARS was evaluated by using external data from an open label randomized controlled trial on 574 TB patients. The patients were grouped as adherence group (247 patients) and non-adherence group (327 patients) based on the predicted ARS. And the non-adherence group was randomized divided into a trail group (146 patients) and a control group (181 patients). The intervention for the trail group was custom health educational material aimed to reduce ARS, while the intervention for control groups was general TB education material, which was routinely used in the current local TB control settings. The cumulative non-adherence rates of the three groups were compared with each other after six-month follow-up period of treatment. The ARS system had 7 items which covered the following domains: disease status, psychology, patients' KAP (knowledge, attitude, and practice), regularly life-style and social supports. The score of ARS was 2.38+/-0.18 (mean+/-SD) for adherence patients, and 4.69 +/-0.20 (mean+/-SD) for non-adherence patients (t=8.52, P<0.01). In the randomized controlled trial, the six months cumulative non-adherence rates ware 24.7% for the trail group and it was 41.4% for the control group(P<0.01); while the six months cumulative non-adherence rates were not statistical significant difference between trail group and adherence group (P>0.05). The ARS system was reliability and validity for evaluating the adherence of TB treatment in the stop TB settings in China.

Microstructural and crystallographic imperfections of MgB2 superconducting wire and their correlation with the critical current density

NASA Astrophysics Data System (ADS)

Shahabuddin, Mohammed; Alzayed, Nasser S.; Oh, Sangjun; Choi, Seyong; Maeda, Minoru; Hata, Satoshi; Shimada, Yusuke; Hossain, Md Shahriar Al; Kim, Jung Ho

2014-01-01

A comprehensive study of the effects of structural imperfections in MgB2 superconducting wire has been conducted. As the sintering temperature becomes lower, the structural imperfections of the MgB2 material are increased, as reflected by detailed X-ray refinement and the normal state resistivity. The crystalline imperfections, caused by lattice disorder, directly affect the impurity scattering between the π and σ bands of MgB2, resulting in a larger upper critical field. In addition, low sintering temperature keeps the grain size small, which leads to a strong enhancement of pinning, and thereby, enhanced critical current density. Owing to both the impurity scattering and the grain boundary pinning, the critical current density, irreversibility field, and upper critical field are enhanced. Residual voids or porosities obviously remain in the MgB2, however, even at low sintering temperature, and thus block current transport paths.

Optical identification using imperfections in 2D materials

NASA Astrophysics Data System (ADS)

Cao, Yameng; Robson, Alexander J.; Alharbi, Abdullah; Roberts, Jonathan; Woodhead, Christopher S.; Noori, Yasir J.; Bernardo-Gavito, Ramón; Shahrjerdi, Davood; Roedig, Utz; Fal'ko, Vladimir I.; Young, Robert J.

2017-12-01

The ability to uniquely identify an object or device is important for authentication. Imperfections, locked into structures during fabrication, can be used to provide a fingerprint that is challenging to reproduce. In this paper, we propose a simple optical technique to read unique information from nanometer-scale defects in 2D materials. Imperfections created during crystal growth or fabrication lead to spatial variations in the bandgap of 2D materials that can be characterized through photoluminescence measurements. We show a simple setup involving an angle-adjustable transmission filter, simple optics and a CCD camera can capture spatially-dependent photoluminescence to produce complex maps of unique information from 2D monolayers. Atomic force microscopy is used to verify the origin of the optical signature measured, demonstrating that it results from nanometer-scale imperfections. This solution to optical identification with 2D materials could be employed as a robust security measure to prevent counterfeiting.

Successful hazard analysis critical control point implementation in the United Kingdom: understanding the barriers through the use of a behavioral adherence model.

PubMed

Gilling, S J; Taylor, E A; Kane, K; Taylor, J Z

2001-05-01

Hazard analysis critical control point (HACCP), a system of risk management designed to control food safety, has emerged over the last decade as the primary approach to securing the safety of the food supply. It is thus an important tool in combatting the worldwide escalation of foodborne disease. Yet despite wide dissemination and scientific support of its principles, successful HACCP implementation has been limited. This report takes a psychological approach to this problem by examining processes and factors that could impede adherence to the internationally accepted HACCP Guidelines and subsequent successful implementation of HACCP. Utilizing knowledge of medical clinical guideline adherence models and practical experience of HACCP implementation problems, the potential advantages of applying a behavioral model to food safety management are highlighted. The models' applicability was investigated using telephone interviews from over 200 businesses in the United Kingdom. Eleven key barriers to HACCP guideline adherence were identified. In-depth narrative interviews with food business proprietors then confirmed these findings and demonstrated the subsequent negative effect(s) on HACCP implementation. A resultant HACCP awareness to adherence model is proposed that demonstrates the complex range of potential knowledge, attitude, and behavior-related barriers involved in failures of HACCP guideline adherence. The model's specificity and detail provide a tool whereby problems can be identified and located and in this way facilitate tailored and constructive intervention. It is suggested that further investigation into the barriers involved and how to overcome them would be of substantial benefit to successful HACCP implementation and thereby contribute to an overall improvement in public health.

Method and system for dynamic probabilistic risk assessment

NASA Technical Reports Server (NTRS)

Dugan, Joanne Bechta (Inventor); Xu, Hong (Inventor)

2013-01-01

The DEFT methodology, system and computer readable medium extends the applicability of the PRA (Probabilistic Risk Assessment) methodology to computer-based systems, by allowing DFT (Dynamic Fault Tree) nodes as pivot nodes in the Event Tree (ET) model. DEFT includes a mathematical model and solution algorithm, supports all common PRA analysis functions and cutsets. Additional capabilities enabled by the DFT include modularization, phased mission analysis, sequence dependencies, and imperfect coverage.

Cost and clinical consequence of antibiotic non-adherence in acute exacerbations of chronic bronchitis.

PubMed

Sorensen, S V; Baker, T; Fleurence, R; Dixon, J; Roberts, C; Haider, S; Hughes, D

2009-08-01

To quantify the impact of non-adherence on the clinical effectiveness of antibiotics for acute exacerbations of chronic bronchitis (AECB) and to estimate the economic consequences for Spain, Italy and the United States. Standard systematic reviewing procedures were followed to identify randomised controlled clinical trials of antibiotic treatment for acute respiratory tract infection for which adherence was reported. A decision-analytic model was then constructed to evaluate the impact of non-adherence to antibiotic treatment on clinical effectiveness and costs per AECB episode. The model compared the total treatment costs, cure rates and incremental costs per cure for a poor compliance group (PCG) against a good compliance group (GCG). Clinical and resource use estimates were from the published literature and physician surveys. Twenty-five articles met the criteria of the systematic review, although only one reported treatment success by adherence status. The relative risk of clinical effectiveness if non-adherent was 0.75 (95%CI 0.73-0.78). Based on this single study, the model predicted that 16-29% more patients would be cured in the GCG vs. the PCG, and payers would save up to euro122, euro179 and US$141 per AECB episode in Spain, Italy and the United States, respectively. Non-adherence to antibiotics for AECB may have an impact on clinical effectiveness, which is associated with increased costs.

Stable Caloric Intake and Continued Virologic Suppression for HIV-Positive Antiretroviral Treatment-Experienced Women After Switching to a Single-Tablet Regimen of Emtricitabine, Rilpivirine, and Tenofovir Disoproxil Fumarate.

PubMed

Menezes, Prema; Mollan, Katie; Hoffman, Erin; Xie, Zimeng; Wills, Jennifer; Marcus, Cheryl; Rublein, John; Hudgens, Michael; Eron, Joseph J

2018-05-02

Benefits of switching to a single-tablet regimen (STR) of emtricitabine/rilpivirine/tenofovir (FTC/RPV/TDF) in virologically suppressed antiretroviral treatment (ART) experienced HIV-positive women include pregnancy category B rating and lack of clinically significant drug interactions between RPV and oral contraceptives. Unfortunately, studies involving switching to FTC/RPV/TDF enrolled fewer than 25% women. We undertook this 48-week study to assess the ability of virologically suppressed HIV-positive women switching to RPV STR to remain virologically suppressed and comply with the caloric intake requirement. HIV-positive women on ART with viral load <50 c/mL for 6 months before study entry and no known resistance to FTC, TDF, or RPV were enrolled and switched to STR RPV/FTC/TDF. Caloric intake (≥400 kcal) compliance and concurrency with oral STR RPV/FTC/TDF were evaluated with a 3-day food diary, which was validated by obtaining participant's caloric consumption through phone calls on randomly chosen dates. For each 3-day food diary, the daily median caloric intake and median value for each macronutrient consumed concurrent with FTC/RPV/TDF were computed. Medication adherence was measured using a visual analog scale. We enrolled 33 women, 73% of whom were African American. At week 48, virologic suppression (HIV RNA <40 c/mL) was maintained in 96% of women, including those (n = 4) who reported imperfect ART adherence. The daily median caloric intake concurrent with FTC/RPV/TDF was 820 kcal by food diary and 677 kcal by random phone call. Median kcal intake (food diary) did not change significantly from baseline (684 kcal) to week 48 (820 kcal); median change 102 kcal, p = .15. Women who reported noncompliance with a ≥400 kcal meal did not experience virologic failure. Significant concordance between caloric adherence and virologic suppression was not detected. Our study demonstrated that HIV-positive women who switched to STR FTC/RPV/TDF continued to experience virologic suppression and were readily able to comply with the recommended caloric intake requirement.

Longitudinal relationships between antiretroviral treatment adherence and discrimination due to HIV-serostatus, race, and sexual orientation among African-American men with HIV.

PubMed

Bogart, Laura M; Wagner, Glenn J; Galvan, Frank H; Klein, David J

2010-10-01

African-Americans show worse HIV disease outcomes compared to Whites. Health disparities may be aggravated by discrimination, which is associated with worse health and maladaptive health behaviors. We examined longitudinal effects of discrimination on antiretroviral treatment adherence among 152 HIV-positive Black men who have sex with men. We measured adherence and discrimination due to HIV-serostatus, race/ethnicity, and sexual orientation at baseline and monthly for 6 months. Hierarchical repeated-measures models tested longitudinal effects of each discrimination type on adherence. Over 6 months, participants took 60% of prescribed medications on average; substantial percentages experienced discrimination (HIV-serostatus, 38%; race/ethnicity, 40%; and sexual orientation, 33%). Greater discrimination due to all three characteristics was significantly bivariately associated with lower adherence (all p's < 0.05). In the multivariate model, only racial discrimination was significant (p < 0.05). Efforts to improve HIV treatment adherence should consider the context of multiple stigmas, especially racism.

Longitudinal Trajectories of Parental Involvement in Type 1 Diabetes and Adolescents’ Adherence

PubMed Central

King, Pamela S.; Berg, Cynthia A.; Butner, Jonathan; Butler, Jorie M.; Wiebe, Deborah J.

2016-01-01

Objective The purpose of this study was to examine longitudinal trajectories of parental involvement and adolescent adherence to the Type 1 diabetes regimen, to determine whether changes in multiple facets of parental involvement over time predicted subsequent changes in adolescents’ adherence, and to examine whether adolescent self-efficacy mediated the effect of parental involvement on adherence. Method Two hundred fifty-two adolescents (M age = 12.49 years, SD = 1.53; 53.6% females) diagnosed with Type 1 diabetes mellitus, their mothers, and 188 fathers were enrolled in a 2.5-year longitudinal study. Across 5 time points, up to 252 adolescents and their parents completed measures of adherence, parental involvement (diabetes monitoring, behavioral involvement in diabetes management, and acceptance), and adolescent diabetes self-efficacy. Results Using multilevel modeling, analyses indicated significant average declines over time in adherence and most indicators of parental involvement. Lagged multilevel models indicated that declines in mothers’ and fathers’ acceptance and diabetes monitoring predicted subsequent declines in adolescents’ adherence. Additional analyses revealed that longitudinal associations between both maternal acceptance and diabetes monitoring and subsequent adolescent adherence were mediated by adolescents’ self-efficacy. Conclusions Results of this study, which were largely consistent across reporters, highlight the importance of maintaining parental involvement in diabetes across adolescence and suggest that parental involvement is beneficial for adolescents’ adherence, in part, because it contributes to higher self-efficacy for diabetes management among adolescents. PMID:23795709

Evaluative coping, emotional distress, and adherence in couples with Type 2 diabetes.

PubMed

Trump, Lisa J; Novak, Joshua R; Anderson, Jared R; Mendenhall, Tai J; Johnson, Matthew D; Scheufler, Ann C; Wilcox, Allison; Lewis, Virginia L; Robbins, David C

2018-03-01

Spousal support is one of the strongest and most consistent predictors of Type 2 diabetes treatment adherence. However, the effects of both spouses' evaluations of dyadic coping on emotional distress and patients' physical health remain largely unknown. Dyadic data from 117 married couples in which one member is diagnosed with Type 2 diabetes were evaluated in two separate models to explore the associations between (a) patients' and spouses' depression symptoms and patients' adherence to dietary and exercise regimens, and (b) patients' and spouses' acute stress levels and patients' adherence to dietary and exercise regimens. Finally, evaluative dyadic coping was included as a possible moderator between these associations. Results from an actor-partner interdependence model revealed significant actor effects of patients' depression symptoms on patients' adherence to dietary and exercise regimens. Spouses' evaluation of dyadic coping attenuated the direct paths between spouses' depression symptoms and patients' adherence to dietary regimens. No direct pathways were found from patients' or spouses' acute stress to patients' adherence to dietary and exercise regimens. However, spouses' evaluation of dyadic coping attenuated the direct paths between spouses' acute stress and patients' adherence to dietary regimens. Tapping into spouses' evaluations of dyadic coping has significant implications for patients' diabetes health outcomes (e.g., adherence to dietary and exercise treatment regimens). Findings from this study highlight the need for systemic interventions targeting both partners. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Statin adherence and risk of acute cardiovascular events among women: a cohort study accounting for time-dependent confounding affected by previous adherence.

PubMed

Lavikainen, Piia; Helin-Salmivaara, Arja; Eerola, Mervi; Fang, Gang; Hartikainen, Juha; Huupponen, Risto; Korhonen, Maarit Jaana

2016-06-03

Previous studies on the effect of statin adherence on cardiovascular events in the primary prevention of cardiovascular disease have adjusted for time-dependent confounding, but potentially introduced bias into their estimates as adherence and confounders were measured simultaneously. We aimed to evaluate the effect when accounting for time-dependent confounding affected by previous adherence as well as time sequence between factors. Retrospective cohort study. Finnish healthcare registers. Women aged 45-64 years initiating statin use for primary prevention of cardiovascular disease in 2001-2004 (n=42 807). Acute cardiovascular event defined as a composite of acute coronary syndrome and acute ischaemic stroke was our primary outcome. Low-energy fractures were used as a negative control outcome to evaluate the healthy-adherer effect. During the 3-year follow-up, 474 women experienced the primary outcome event and 557 suffered a low-energy fracture. The causal HR estimated with marginal structural model for acute cardiovascular events for all the women who remained adherent (proportion of days covered ≥80%) to statin therapy during the previous adherence assessment year was 0.78 (95% CI: 0.65 to 0.94) when compared with everybody remaining non-adherent (proportion of days covered <80%). The result was robust against alternative model specifications. Statin adherers had a potentially reduced risk of experiencing low-energy fractures compared with non-adherers (HR 0.90, 95% CI 0.76 to 1.07). Our study, which took into account the time dependence of adherence and confounders, as well as temporal order between these factors, is support for the concept that adherence to statins in women in primary prevention decreases the risk of acute cardiovascular events by about one-fifth in comparison to non-adherence. However, part of the observed effect of statin adherence on acute cardiovascular events may be due to the healthy-adherer effect. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Psychometrics of a new questionnaire to assess glaucoma adherence: the Glaucoma Treatment Compliance Assessment Tool (an American Ophthalmological Society thesis).

PubMed

Mansberger, Steven L; Sheppler, Christina R; McClure, Tina M; Vanalstine, Cory L; Swanson, Ingrid L; Stoumbos, Zoey; Lambert, William E

2013-09-01

To report the psychometrics of the Glaucoma Treatment Compliance Assessment Tool (GTCAT), a new questionnaire designed to assess adherence with glaucoma therapy. We developed the questionnaire according to the constructs of the Health Belief Model. We evaluated the questionnaire using data from a cross-sectional study with focus groups (n = 20) and a prospective observational case series (n=58). Principal components analysis provided assessment of construct validity. We repeated the questionnaire after 3 months for test-retest reliability. We evaluated predictive validity using an electronic dosing monitor as an objective measure of adherence. Focus group participants provided 931 statements related to adherence, of which 88.7% (826/931) could be categorized into the constructs of the Health Belief Model. Perceived barriers accounted for 31% (288/931) of statements, cues-to-action 14% (131/931), susceptibility 12% (116/931), benefits 12% (115/931), severity 10% (91/931), and self-efficacy 9% (85/931). The principal components analysis explained 77% of the variance with five components representing Health Belief Model constructs. Reliability analyses showed acceptable Cronbach's alphas (>.70) for four of the seven components (severity, susceptibility, barriers [eye drop administration], and barriers [discomfort]). Predictive validity was high, with several Health Belief Model questions significantly associated (P <.05) with adherence and a correlation coefficient (R (2)) of .40. Test-retest reliability was 90%. The GTCAT shows excellent repeatability, content, construct, and predictive validity for glaucoma adherence. A multisite trial is needed to determine whether the results can be generalized and whether the questionnaire accurately measures the effect of interventions to increase adherence.

Machine learning classification of medication adherence in patients with movement disorders using non-wearable sensors.

PubMed

Tucker, Conrad S; Behoora, Ishan; Nembhard, Harriet Black; Lewis, Mechelle; Sterling, Nicholas W; Huang, Xuemei

2015-11-01

Medication non-adherence is a major concern in the healthcare industry and has led to increases in health risks and medical costs. For many neurological diseases, adherence to medication regimens can be assessed by observing movement patterns. However, physician observations are typically assessed based on visual inspection of movement and are limited to clinical testing procedures. Consequently, medication adherence is difficult to measure when patients are away from the clinical setting. The authors propose a data mining driven methodology that uses low cost, non-wearable multimodal sensors to model and predict patients' adherence to medication protocols, based on variations in their gait. The authors conduct a study involving Parkinson's disease patients that are "on" and "off" their medication in order to determine the statistical validity of the methodology. The data acquired can then be used to quantify patients' adherence while away from the clinic. Accordingly, this data-driven system may allow for early warnings regarding patient safety. Using whole-body movement data readings from the patients, the authors were able to discriminate between PD patients on and off medication, with accuracies greater than 97% for some patients using an individually customized model and accuracies of 78% for a generalized model containing multiple patient gait data. The proposed methodology and study demonstrate the potential and effectiveness of using low cost, non-wearable hardware and data mining models to monitor medication adherence outside of the traditional healthcare facility. These innovations may allow for cost effective, remote monitoring of treatment of neurological diseases. Copyright © 2015 Elsevier Ltd. All rights reserved.

Machine Learning Classification of Medication Adherence in Patients with Movement Disorders Using Non-Wearable Sensors

PubMed Central

Tucker, Conrad; Behoora, Ishan; Nembhard, Harriet Black; Lewis, Mechelle; Sterling, Nicholas W; Huang, Xuemei

2017-01-01

Medication non-adherence is a major concern in the healthcare industry and has led to increases in health risks and medical costs. For many neurological diseases, adherence to medication regimens can be assessed by observing movement patterns. However, physician observations are typically assessed based on visual inspection of movement and are limited to clinical testing procedures. Consequently, medication adherence is difficult to measure when patients are away from the clinical setting. The authors propose a data mining driven methodology that uses low cost, non-wearable multimodal sensors to model and predict patients’ adherence to medication protocols, based on variations in their gait. The authors conduct a study involving Parkinson’s Disease patients that are “on” and “off” their medication in order to determine the statistical validity of the methodology. The data acquired can then be used to quantify patients’ adherence while away from the clinic. Accordingly, this data-driven system may allow for early warnings regarding patient safety. Using whole-body movement data readings from the patients, the authors were able to discriminate between PD patients on and off medication, with accuracies greater than 97% for some patients using an individually customized model and accuracies of 78% for a generalized model containing multiple patient gait data. The proposed methodology and study demonstrate the potential and effectiveness of using low cost, non-wearable hardware and data mining models to monitor medication adherence outside of the traditional healthcare facility. These innovations may allow for cost effective, remote monitoring of treatment of neurological diseases. PMID:26406881

Developing a measure of provider adherence to improve the implementation of behavioral health services in primary care: a Delphi study

PubMed Central

2013-01-01

Background The integration of behavioral health services into primary care is increasingly popular, yet fidelity of implementation in this area has been infrequently assessed due to the few measurement tools available. A sentinel indicator of fidelity of implementation is provider adherence, or utilization of prescribed procedures and engagement in model-specific behaviors. This study aimed to develop the first self-report measure of behavioral health provider adherence for co-located, collaborative care, a commonly adopted model of behavioral health service delivery in primary care. Methods A preliminary 56-item measure was developed by the research team to represent critical components of adherence among behavioral health providers. To ensure the content validity of the measure, a modified Delphi study was conducted using a panel of co-located, collaborative care model experts. During three rounds of emailed surveys, panel members provided qualitative feedback regarding item content while rating each item’s relevance for behavioral health provider practice. Items with consensus ratings of 80% or greater were included in the final adherence measure. Results The panel consisted of 25 experts representing the Department of Veterans Affairs, the Department of Defense, and academic and community health centers (total study response rate of 76%). During the Delphi process, two new items were added to the measure, four items were eliminated, and a high level of consensus was achieved on the remaining 54 items. Experts identified 38 items essential for model adherence, six items compatible (although not essential) for model adherence, and 10 items that represented prohibited behaviors. Item content addressed several domains, but primarily focused on behaviors related to employing a time-limited, brief treatment model, the scope of patient concerns addressed, and interventions used by providers. Conclusions This study yielded the first content valid self-report measure of critical components of collaborative care adherence for use by behavioral health providers in primary care. Although additional psychometric evaluation is necessary, this measure may assist implementation researchers in clarifying how provider behaviors contribute to clinical outcomes. This measure may also assist clinical stakeholders in monitoring implementation and identifying ways to support frontline providers in delivering high quality services. PMID:23406425

Effect of oxiplex* films (PEO/CMC) on adhesion formation and reformation in rabbit models and on peritoneal infection in a rat model.

PubMed

Rodgers, K E; Schwartz, H E; Roda, N; Thornton, M; Kobak, W; diZerega, G S

2000-04-01

To assess the efficacy of Oxiplex (FzioMed, Inc., San Luis Obispo, CA) barriers. Film of polyethylene oxide and carboxymethylcellulose (Oxiplex) were tested for strength and tissue adherence. Films were selected for evaluation in models for biocompatability and adherence. Three films were selected for evaluation in efficacy studies, and one was evaluated for effects on bacterial peritonitis. Handling characteristics of Oxiplex film were evaluated via laparoscopy. University laboratory. Rabbits, rats, pigs. Placement of Oxiplex prototypes at the site of injury. Mechanical properties, biocompatibility, tissue adherence, adhesion development, infection potentiation, and device handling. Mechanical tests indicated that tensile strength and elongation were inversely correlated. All films tested had excellent tissue adherence properties. Selected films, based on residence time and biocompatibility, prevented adhesion formation in all animals and were highly efficacious in preventing adhesion reformation. The optimal Oxiplex prototype prevented adhesion reformation in 91% of the animals. This Oxiplex film, dyed to allow visualization, prevented adhesion reformation and did not affect bacterial peritonitis. In a laparoscopic model, the Oxiplex film, delivered in FilmSert forceps, via a 5.0-mm trocar, rapidly unfurled and could be easily applied to tissue with strong adherence. These data show development of an adhesion prevention material that is tissue adherent, can be placed via laparoscopy, and does not affect host resistance.

The Problem of Controlling for Imperfectly Measured Confounders on Dissimilar Populations: A Database Simulation Study

PubMed Central

Schonberger, Robert B; Gilbertsen, Todd; Dai, Feng

2013-01-01

Objective(s) Observational database research frequently relies on imperfect administrative markers to determine comorbid status, and it is difficult to infer to what extent the associated misclassification impacts validity in multivariable analyses. The effect that imperfect markers of disease will have on validity in situations where researchers attempt to match populations that have strong baseline health differences is underemphasized as a limitation in some otherwise high-quality observational studies. The present simulations were designed as a quantitative demonstration of the importance of this common and underappreciated issue. Design Two groups of Monte Carlo simulations were performed. The first demonstrated the degree to which controlling for a series of imperfect markers of disease between different populations taking 2 hypothetically harmless drugs would lead to spurious associations between drug assignment and mortality. The second Monte Carlo simulation applied this principle to a recent study in the field of anesthesiology that purported to show increased perioperative mortality in patients taking metoprolol versus atenolol. Setting/Participants/Interventions None. Measurements and Main Results Simulation 1: High type 1 error (ie, false positive findings of an independent association between drug assignment and mortality) was observed as sensitivity and specificity declined and as systematic differences in disease prevalence increased. Simulation 2: Propensity score matching across several imperfect markers was unlikely to eliminate important baseline health disparities in the referenced study. Conclusions In situations where large baseline health disparities exist between populations, matching on imperfect markers of disease may result in strong bias away from the null hypothesis. PMID:23962461

Interest rates in quantum finance: the Wilson expansion and Hamiltonian.

PubMed

Baaquie, Belal E

2009-10-01

Interest rate instruments form a major component of the capital markets. The Libor market model (LMM) is the finance industry standard interest rate model for both Libor and Euribor, which are the most important interest rates. The quantum finance formulation of the Libor market model is given in this paper and leads to a key generalization: all the Libors, for different future times, are imperfectly correlated. A key difference between a forward interest rate model and the LMM lies in the fact that the LMM is calibrated directly from the observed market interest rates. The short distance Wilson expansion [Phys. Rev. 179, 1499 (1969)] of a Gaussian quantum field is shown to provide the generalization of Ito calculus; in particular, the Wilson expansion of the Gaussian quantum field A(t,x) driving the Libors yields a derivation of the Libor drift term that incorporates imperfect correlations of the different Libors. The logarithm of Libor phi(t,x) is defined and provides an efficient and compact representation of the quantum field theory of the Libor market model. The Lagrangian and Feynman path integrals of the Libor market model of interest rates are obtained, as well as a derivation given by its Hamiltonian. The Hamiltonian formulation of the martingale condition provides an exact solution for the nonlinear drift of the Libor market model. The quantum finance formulation of the LMM is shown to reduce to the industry standard Bruce-Gatarek-Musiela-Jamshidian model when the forward interest rates are taken to be exactly correlated.

Implementing Lumberjacks and Black Swans Into Model-Based Tools to Support Human-Automation Interaction.

PubMed

Sebok, Angelia; Wickens, Christopher D

2017-03-01

The objectives were to (a) implement theoretical perspectives regarding human-automation interaction (HAI) into model-based tools to assist designers in developing systems that support effective performance and (b) conduct validations to assess the ability of the models to predict operator performance. Two key concepts in HAI, the lumberjack analogy and black swan events, have been studied extensively. The lumberjack analogy describes the effects of imperfect automation on operator performance. In routine operations, an increased degree of automation supports performance, but in failure conditions, increased automation results in more significantly impaired performance. Black swans are the rare and unexpected failures of imperfect automation. The lumberjack analogy and black swan concepts have been implemented into three model-based tools that predict operator performance in different systems. These tools include a flight management system, a remotely controlled robotic arm, and an environmental process control system. Each modeling effort included a corresponding validation. In one validation, the software tool was used to compare three flight management system designs, which were ranked in the same order as predicted by subject matter experts. The second validation compared model-predicted operator complacency with empirical performance in the same conditions. The third validation compared model-predicted and empirically determined time to detect and repair faults in four automation conditions. The three model-based tools offer useful ways to predict operator performance in complex systems. The three tools offer ways to predict the effects of different automation designs on operator performance.

Statistical Analysis for Multisite Trials Using Instrumental Variables with Random Coefficients

ERIC Educational Resources Information Center

Raudenbush, Stephen W.; Reardon, Sean F.; Nomi, Takako

2012-01-01

Multisite trials can clarify the average impact of a new program and the heterogeneity of impacts across sites. Unfortunately, in many applications, compliance with treatment assignment is imperfect. For these applications, we propose an instrumental variable (IV) model with person-specific and site-specific random coefficients. Site-specific IV…

Reduction of stresses on buried rigid highway structures using the imperfect ditch method and expanded polysterene : geofoam.

DOT National Transportation Integrated Search

2009-01-01

This study provides strong evidences from both numerical model analysis and in-situ test data to indicate that geofoam is an ideal elasto-plastic material to reduce vertical load on top of rigid culvert resting on a rigid foundation. The load on the ...

An Extended Production and Inspection Model with Nonrigid Demand

PubMed Central

Shih, Neng-Hui; Wang, Chih-Hsiung

2013-01-01

This paper extends a previous production and inspection (PI) model in relation to market demand that is nonrigid to consider an imperfect process that has a general hazard rate instead of a constant failure rate. Products are produced by an imperfect process that may shift randomly from the IN state to the OUT state. When the process is in the OUT state, it has a higher probability of producing a nonconforming product than when it is in the IN state. To achieve the zero defects policy, all products before delivery to the market should be inspected and the inspection order follows their production sequence. Furthermore, the inspection information from all previous products is used to decide either that the next candidate product should be inspected or that the inspection procedure for the current production lot should be terminated. When the inspection procedure is terminated, the remaining unmet demand is regarded as a shortage. An algorithm is developed to determine an optimal PI policy that minimizes the expected total cost, which includes the cost of inspection, of shortage, and of production. PMID:24396302

Application of Rasch analysis to the parent adherence report questionnaire in juvenile idiopathic arthritis.

PubMed

Toupin April, Karine; Higgins, Johanne; Ehrmann Feldman, Debbie

2016-07-28

Adherence to treatment in children with juvenile idiopathic arthritis (JIA) is associated with better outcomes. Assessing patient adherence in JIA, as well as attitudes and beliefs about prescribed treatments, is important for the clinician in order to optimize patient management. The objective of the current study was to evaluate the psychometric properties of the Parent (proxy-report) Adherence Report Questionnaires (PARQ), which assesses beliefs and behaviors related to adherence to treatments prescribed for JIA. A Rasch analysis was conducted on data collected with parents of children with JIA from two studies in which the PARQ was used as a measure of adherence. The PARQ showed preliminary evidence of multidimensionality with two factors, accounting for 38 % and 27 % of the variance respectively. The PARQ in its original version does not adhere to expectations of the Rasch model. A transformed version of the PARQ obtained by deletion of the general adherence scale and modification of visual analog scales into 5-point likert scales improved fit to the model and showed preliminary evidence of unidimensionality. The PARQ was transformed based on the results of the Rasch analysis. The transformed version of the PARQ shows preliminary evidence of unidimensionality and may allow computation of a total score, although further testing is needed to verify these findings.

Can purchasing information be used to predict adherence to cardiovascular medications? An analysis of linked retail pharmacy and insurance claims data

PubMed Central

Krumme, Alexis A; Sanfélix-Gimeno, Gabriel; Franklin, Jessica M; Isaman, Danielle L; Mahesri, Mufaddal; Matlin, Olga S; Shrank, William H; Brennan, Troyen A; Brill, Gregory; Choudhry, Niteesh K

2016-01-01

Objective The use of retail purchasing data may improve adherence prediction over approaches using healthcare insurance claims alone. Design Retrospective. Setting and participants A cohort of patients who received prescription medication benefits through CVS Caremark, used a CVS Pharmacy ExtraCare Health Care (ECHC) loyalty card, and initiated a statin medication in 2011. Outcome We evaluated associations between retail purchasing patterns and optimal adherence to statins in the 12 subsequent months. Results Among 11 010 statin initiators, 43% were optimally adherent at 12 months of follow-up. Greater numbers of store visits per month and dollar amount per visit were positively associated with optimal adherence, as was making a purchase on the same day as filling a prescription (p<0.0001 for all). Models to predict adherence using retail purchase variables had low discriminative ability (C-statistic: 0.563), while models with both clinical and retail purchase variables achieved a C-statistic of 0.617. Conclusions While the use of retail purchases may improve the discriminative ability of claims-based approaches, these data alone appear inadequate for adherence prediction, even with the addition of more complex analytical approaches. Nevertheless, associations between retail purchasing behaviours and adherence could inform the development of quality improvement interventions. PMID:28186924

Type D personality, self-efficacy, and medication adherence in patients with heart failure-A mediation analysis.

PubMed

Wu, Jia-Rong; Song, Eun Kyeung; Moser, Debra K

2015-01-01

Type D personality is associated with medication non-adherence. Both Type D personality and non-adherence are predictors of poor outcomes. Self-efficacy, which is modifiable, is also associated with medication adherence. To determine the relationships among Type D personality, self-efficacy, and medication adherence in 84 heart failure patients. Self-efficacy, Type D personality, medication adherence, demographic and clinical data were collected. Hierarchical linear regression was used. Type D patients were more likely to have lower self-efficacy (p = .023) and medication non-adherence (p = .027) than non-Type D patients. Low self-efficacy was associated with medication non-adherence (p < .001). Type D personality didn't predict medication adherence after entering self-efficacy in the model (p = .422), demonstrating mediation. Self-efficacy mediates the relationship between Type D personality and medication adherence. Developing and applying interventions to enhance self-efficacy may help to sever the link between Type D personality and poor outcomes. Copyright © 2015 Elsevier Inc. All rights reserved.

Numerical and experimental investigation of the bending response of thin-walled composite cylinders

NASA Technical Reports Server (NTRS)

Fuchs, J. P.; Hyer, M. W.; Starnes, J. H., Jr.

1993-01-01

A numerical and experimental investigation of the bending behavior of six eight-ply graphite-epoxy circular cylinders is presented. Bending is induced by applying a known end-rotation to each end of the cylinders, analogous to a beam in bending. The cylinders have a nominal radius of 6 inches, a length-to-radius ratio of 2 and 5, and a radius-to-thickness ratio of approximately 160. A (+/- 45/0/90)S quasi-isotropic layup and two orthotropic layups, (+/- 45/0 sub 2)S and (+/- 45/90 sub 2)S, are studied. A geometrically nonlinear special-purpose analysis, based on Donnell's nonlinear shell equations, is developed to study the prebuckling responses and gain insight into the effects of non-ideal boundary conditions and initial geometric imperfections. A geometrically nonlinear finite element analysis is utilized to compare with the prebuckling solutions of the special-purpose analysis and to study the buckling and post buckling responses of both geometrically perfect and imperfect cylinders. The imperfect cylinder geometries are represented by an analytical approximation of the measured shape imperfections. Extensive experimental data are obtained from quasi-static tests of the cylinders using a test fixture specifically designed for the present investigation. A description of the test fixture is included. The experimental data are compared to predictions for both perfect and imperfect cylinder geometries. Prebuckling results are presented in the form of displacement and strain profiles. Buckling end-rotations, moments, and strains are reported, and predicted mode shapes are presented. Observed and predicted moment vs. end-rotation relations, deflection patterns, and strain profiles are illustrated for the post buckling responses. It is found that a geometrically nonlinear boundary layer behavior characterizes the prebuckling responses. The boundary layer behavior is sensitive to laminate orthotropy, cylinder geometry, initial geometric imperfections, applied end-rotation, and non-ideal boundary conditions. Buckling end-rotations, strains, and moments are influenced by laminate orthotropy and initial geometric imperfections. Measured buckling results correlate well with predictions for the geometrically imperfect specimens. The postbuckling analyses predict equilibrium paths with a number of scallop-shaped branches that correspond to unique deflection patterns. The observed postbuckling deflection patterns and measured strain profiles show striking similarities to the predictions in some cases. Ultimate failure of the cylinders is attributed to an interlaminar shear failure mode along the nodal lines of the postbuckling deflection patterns.

Adherence to isoniazid prophylaxis among HIV-infected children: a randomized controlled trial comparing two dosing schedules

PubMed Central

le Roux, Stanzi M; Cotton, Mark F; Golub, Jonathan E; le Roux, David M; Workman, Lesley; Zar, Heather J

2009-01-01

Background Tuberculosis contributes significantly to morbidity and mortality among HIV-infected children in sub-Saharan Africa. Isoniazid prophylaxis can reduce tuberculosis incidence in this population. However, for the treatment to be effective, adherence to the medication must be optimized. We investigated adherence to isoniazid prophylaxis administered daily, compared to three times a week, and predictors of adherence amongst HIV-infected children. Methods We investigated adherence to study medication in a two centre, randomized trial comparing daily to three times a week dosing of isoniazid. The study was conducted at two tertiary paediatric care centres in Cape Town, South Africa. Over a 5 year period, we followed 324 HIV-infected children aged ≥ 8 weeks. Adherence information based on pill counts was available for 276 children. Percentage adherence was calculated by counting the number of pills returned. Adherence ≥ 90% was considered to be optimal. Analysis was done using summary and repeated measures, comparing adherence to the two dosing schedules. Mean percentage adherence (per child during follow-up time) was used to compare the mean of each group as well as the proportion of children achieving an adherence of ≥ 90% in each group. For repeated measures, percentage adherence (per child per visit) was dichotomized at 90%. A logistic regression model with generalized estimating equations, to account for within-individual correlation, was used to evaluate the impact of the dosing schedule. Adjustments were made for potential confounders and we assessed potential baseline and time-varying adherence determinants. Results The overall adherence to isoniazid was excellent, with a mean adherence of 94.7% (95% confidence interval [CI] 93.5-95.9); similar mean adherence was achieved by the group taking daily medication (93.8%; 95% CI 92.1-95.6) and by the three times a week group (95.5%; 95% CI 93.8-97.2). Two-hundred and seventeen (78.6%) children achieved a mean adherence of ≥ 90%. Adherence was similar for daily and three times a week dosing schedules in univariate (odds ratio [OR] 0.88; 95% CI 0.66-1.17; P = 0.38) and multivariate (adjusted OR 0.85; 95% CI 0.64-1.11; P = 0.23) models. Children from overcrowded homes were less adherent (adjusted OR 0.71; 95% CI 0.54-0.95; P = 0.02). Age at study visit was predictive of adherence, with better adherence achieved in children older than 4 years (adjusted OR 1.96; 95% CI 1.16-3.32; P = 0.01). Conclusion Adherence to isoniazid was excellent regardless of the dosing schedule used. Intermittent dosing of isoniazid prophylaxis can be considered as an alternative to daily dosing, without compromising adherence or efficacy. Trial registration Clinical Trials NCT00330304 PMID:19886982

An actor-focused model of justice rule adherence and violation: the role of managerial motives and discretion.

PubMed

Scott, Brent A; Colquitt, Jason A; Paddock, E Layne

2009-05-01

Research on organizational justice has focused primarily on the receivers of just and unjust treatment. Little is known about why managers adhere to or violate rules of justice in the first place. The authors introduce a model for understanding justice rule adherence and violation. They identify both cognitive motives and affective motives that explain why managers adhere to and violate justice rules. They also draw distinctions among the justice rules by specifying which rules offer managers more or less discretion in their execution. They then describe how motives and discretion interact to influence justice-relevant actions. Finally, the authors incorporate managers' emotional reactions to consider how their actions may change over time. Implications of the model for theory, research, and practice are discussed. (c) 2009 APA, all rights reserved.

Acoustic resonance scattering from a multilayered cylindrical shell with imperfect bonding.

PubMed

Rajabi, M; Hasheminejad, Seyyed M

2009-12-01

The method of wave function expansion is adopted to study the three dimensional scattering of a time-harmonic plane progressive sound field obliquely incident upon a multi-layered hollow cylinder with interlaminar bonding imperfection. For the generality of solution, each layer is assumed to be cylindrically orthotropic. An approximate laminate model in the context of the modal state equations with variable coefficients along with the classical T-matrix solution technique is set up for each layer to solve for the unknown modal scattering and transmission coefficients. A linear spring model is used to describe the interlaminar adhesive bonding whose effects are incorporated into the global transfer matrix by introduction of proper interfacial transfer matrices. Following the classic acoustic resonance scattering theory (RST), the scattered field and response to surface waves are determined by constructing the partial waves and obtaining the non-resonance (backgrounds) and resonance components. The solution is first used to investigate the effect of interlayer imperfection of an air-filled and water submerged bilaminate aluminium cylindrical shell on the resonances associated with various modes of wave propagation (i.e., symmetric/asymmetric Lamb waves, fluid-borne A-type waves, Rayleigh and Whispering Gallery waves) appearing in the backscattered spectrum, according to their polarization and state of stress. An illustrative numerical example is also given for a multi-layered (five-layered) cylindrical shell for which the stiffness of the adhesive interlayers is artificially varied. The sensitivity of resonance frequencies associated with higher mode numbers to the stiffness coefficients is demonstrated to be a good measure of the bonding strength. Limiting cases are considered and fair agreements with solutions available in the literature are established.

Beyond Testing: Empirical Models of Insurance Markets

PubMed Central

Einav, Liran; Finkelstein, Amy; Levin, Jonathan

2011-01-01

We describe recent advances in the empirical analysis of insurance markets. This new research proposes ways to estimate individual demand for insurance and the relationship between prices and insurer costs in the presence of adverse and advantageous selection. We discuss how these models permit the measurement of welfare distortions arising from asymmetric information and the welfare consequences of potential government policy responses. We also discuss some challenges in modeling imperfect competition between insurers and outline a series of open research questions. PMID:21572939

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tuo, Rui; Wu, C. F. Jeff

Many computer models contain unknown parameters which need to be estimated using physical observations. Furthermore, the calibration method based on Gaussian process models may lead to unreasonable estimate for imperfect computer models. In this work, we extend their study to calibration problems with stochastic physical data. We propose a novel method, called the L 2 calibration, and show its semiparametric efficiency. The conventional method of the ordinary least squares is also studied. Theoretical analysis shows that it is consistent but not efficient. Here, numerical examples show that the proposed method outperforms the existing ones.

Modeling and Analysis of Composite Wing Sections for Improved Aeroelastic and Vibration Characteristics Using Smart Materials

NASA Technical Reports Server (NTRS)

Chattopadhyay, Aditi

1996-01-01

The objective of this research is to develop analysis procedures to investigate the coupling of composite and smart materials to improve aeroelastic and vibratory response of aerospace structures. The structural modeling must account for arbitrarily thick geometries, embedded and surface bonded sensors and actuators and imperfections, such as delamination. Changes in the dynamic response due to the presence of smart materials and delaminations is investigated. Experiments are to be performed to validate the proposed mathematical model.

Modeling Dengue Vector Dynamics under Imperfect Detection: Three Years of Site-Occupancy by Aedes aegypti and Aedes albopictus in Urban Amazonia

PubMed Central

Padilla-Torres, Samael D.; Ferraz, Gonçalo; Luz, Sergio L. B.; Zamora-Perea, Elvira; Abad-Franch, Fernando

2013-01-01

Aedes aegypti and Ae. albopictus are the vectors of dengue, the most important arboviral disease of humans. To date, Aedes ecology studies have assumed that the vectors are truly absent from sites where they are not detected; since no perfect detection method exists, this assumption is questionable. Imperfect detection may bias estimates of key vector surveillance/control parameters, including site-occupancy (infestation) rates and control intervention effects. We used a modeling approach that explicitly accounts for imperfect detection and a 38-month, 55-site detection/non-detection dataset to quantify the effects of municipality/state control interventions on Aedes site-occupancy dynamics, considering meteorological and dwelling-level covariates. Ae. aegypti site-occupancy estimates (mean 0.91; range 0.79–0.97) were much higher than reported by routine surveillance based on ‘rapid larval surveys’ (0.03; 0.02–0.11) and moderately higher than directly ascertained with oviposition traps (0.68; 0.50–0.91). Regular control campaigns based on breeding-site elimination had no measurable effects on the probabilities of dwelling infestation by dengue vectors. Site-occupancy fluctuated seasonally, mainly due to the negative effects of high maximum (Ae. aegypti) and minimum (Ae. albopictus) summer temperatures (June-September). Rainfall and dwelling-level covariates were poor predictors of occupancy. The marked contrast between our estimates of adult vector presence and the results from ‘rapid larval surveys’ suggests, together with the lack of effect of local control campaigns on infestation, that many Aedes breeding sites were overlooked by vector control agents in our study setting. Better sampling strategies are urgently needed, particularly for the reliable assessment of infestation rates in the context of control program management. The approach we present here, combining oviposition traps and site-occupancy models, could greatly contribute to that crucial aim. PMID:23472194

Modeling Disease Vector Occurrence When Detection Is Imperfect II: Drivers of Site-Occupancy by Synanthropic Triatoma brasiliensis in the Brazilian Northeast

PubMed Central

Valença-Barbosa, Carolina; Lima, Marli M.; Sarquis, Otília; Bezerra, Claudia M.; Abad-Franch, Fernando

2014-01-01

Background Understanding the drivers of habitat selection by insect disease vectors is instrumental to the design and operation of rational control-surveillance systems. One pervasive yet often overlooked drawback of vector studies is that detection failures result in some sites being misclassified as uninfested; naïve infestation indices are therefore biased, and this can confound our view of vector habitat preferences. Here, we present an initial attempt at applying methods that explicitly account for imperfect detection to investigate the ecology of Chagas disease vectors in man-made environments. Methodology We combined triplicate-sampling of individual ecotopes (n = 203) and site-occupancy models (SOMs) to test a suite of pre-specified hypotheses about habitat selection by Triatoma brasiliensis. SOM results were compared with those of standard generalized linear models (GLMs) that assume perfect detection even with single bug-searches. Principal Findings Triatoma brasiliensis was strongly associated with key hosts (native rodents, goats/sheep and, to a lesser extent, fowl) in peridomestic environments; ecotope structure had, in comparison, small to negligible effects, although wooden ecotopes were slightly preferred. We found evidence of dwelling-level aggregation of infestation foci; when there was one such focus, same-dwelling ecotopes, whether houses or peridomestic structures, were more likely to become infested too. GLMs yielded negatively-biased covariate effect estimates and standard errors; both were, on average, about four times smaller than those derived from SOMs. Conclusions/Significance Our results confirm substantial population-level ecological heterogeneity in T. brasiliensis. They also suggest that, at least in some sites, control of this species may benefit from peridomestic rodent control and changes in goat/sheep husbandry practices. Finally, our comparative analyses highlight the importance of accounting for the various sources of uncertainty inherent to vector studies, including imperfect detection. We anticipate that future research on infectious disease ecology will increasingly rely on approaches akin to those described here. PMID:24811125

The effect of imperfections on the vertical buckling of railroad tracks

DOT National Transportation Integrated Search

1976-06-30

This report deals with an analytical prediction of the effect of geometric imperfections on the post-buckling characteristics of railroad tracks. The analysis is restricted to the case of vertical track buckling due to constrained thermal expansion i...

Increasing the Reliability of Circulation Model Validation: Quantifying Drifter Slip to See how Currents are Actually Moving

NASA Astrophysics Data System (ADS)

Anderson, T.

2016-02-01

Ocean circulation forecasts can help answer questions regarding larval dispersal, passive movement of injured sea animals, oil spill mitigation, and search and rescue efforts. Circulation forecasts are often validated with GPS-tracked drifter paths, but how accurately do these drifters actually move with ocean currents? Drifters are not only moved by water, but are also forced by wind and waves acting on the exposed buoy and transmitter; this imperfect movement is referred to as drifter slip. The quantification and further understanding of drifter slip will allow scientists to differentiate between drifter imperfections and actual computer model error when comparing trajectory forecasts with actual drifter tracks. This will avoid falsely accrediting all discrepancies between a trajectory forecast and an actual drifter track to computer model error. During multiple deployments of drifters in Nantucket Sound and using observed wind and wave data, we attempt to quantify the slip of drifters developed by the Northeast Fisheries Science Center's (NEFSC) Student Drifters Program. While similar studies have been conducted previously, very few have directly attached current meters to drifters to quantify drifter slip. Furthermore, none have quantified slip of NEFSC drifters relative to the oceanographic-standard "CODE" drifter. The NEFSC drifter archive has over 1000 drifter tracks primarily off the New England coast. With a better understanding of NEFSC drifter slip, modelers can reliably use these tracks for model validation.

Increasing the Reliability of Circulation Model Validation: Quantifying Drifter Slip to See how Currents are Actually Moving

NASA Astrophysics Data System (ADS)

Anderson, T.

2015-12-01

Ocean circulation forecasts can help answer questions regarding larval dispersal, passive movement of injured sea animals, oil spill mitigation, and search and rescue efforts. Circulation forecasts are often validated with GPS-tracked drifter paths, but how accurately do these drifters actually move with ocean currents? Drifters are not only moved by water, but are also forced by wind and waves acting on the exposed buoy and transmitter; this imperfect movement is referred to as drifter slip. The quantification and further understanding of drifter slip will allow scientists to differentiate between drifter imperfections and actual computer model error when comparing trajectory forecasts with actual drifter tracks. This will avoid falsely accrediting all discrepancies between a trajectory forecast and an actual drifter track to computer model error. During multiple deployments of drifters in Nantucket Sound and using observed wind and wave data, we attempt to quantify the slip of drifters developed by the Northeast Fisheries Science Center's (NEFSC) Student Drifters Program. While similar studies have been conducted previously, very few have directly attached current meters to drifters to quantify drifter slip. Furthermore, none have quantified slip of NEFSC drifters relative to the oceanographic-standard "CODE" drifter. The NEFSC drifter archive has over 1000 drifter tracks primarily off the New England coast. With a better understanding of NEFSC drifter slip, modelers can reliably use these tracks for model validation.

Augmenting superpopulation capture-recapture models with population assignment data

USGS Publications Warehouse

Wen, Zhi; Pollock, Kenneth; Nichols, James; Waser, Peter

2011-01-01

Ecologists applying capture-recapture models to animal populations sometimes have access to additional information about individuals' populations of origin (e.g., information about genetics, stable isotopes, etc.). Tests that assign an individual's genotype to its most likely source population are increasingly used. Here we show how to augment a superpopulation capture-recapture model with such information. We consider a single superpopulation model without age structure, and split each entry probability into separate components due to births in situ and immigration. We show that it is possible to estimate these two probabilities separately. We first consider the case of perfect information about population of origin, where we can distinguish individuals born in situ from immigrants with certainty. Then we consider the more realistic case of imperfect information, where we use genetic or other information to assign probabilities to each individual's origin as in situ or outside the population. We use a resampling approach to impute the true population of origin from imperfect assignment information. The integration of data on population of origin with capture-recapture data allows us to determine the contributions of immigration and in situ reproduction to the growth of the population, an issue of importance to ecologists. We illustrate our new models with capture-recapture and genetic assignment data from a population of banner-tailed kangaroo rats Dipodomys spectabilis in Arizona.

Adherence to Preexposure Prophylaxis: Current, Emerging, and Anticipated Bases of Evidence

PubMed Central

Amico, K. Rivet; Stirratt, Michael J.

2014-01-01

Despite considerable discussion and debate about adherence to preexposure prophylaxis (PrEP) for human immunodeficiency virus (HIV), scant data are available that characterize patterns of adherence to open-label PrEP. The current evidence base is instead dominated by research on adherence to placebo-controlled investigational drug by way of drug detection in active-arm participants of large randomized controlled trials (RCTs). Important differences between the context of blinded RCTs and open-label use suggest caution when generalizing from study product adherence to real-world PrEP use. Evidence specific to open-label PrEP adherence is presently sparse but will expand rapidly over the next few years as roll-out, demonstration projects, and more rigorous research collect and present findings. The current evidence bases established cannot yet predict uptake, adherence, or persistence with open-label effective PrEP. Emerging evidence suggests that some cohorts could execute better adherence in open-label use vs placebo-controlled research. Uptake of PrEP is presently slow in the United States; whether this changes as grassroots and community efforts increase awareness of PrEP as an effective HIV prevention option remains to be determined. As recommended by multiple guidelines for PrEP use, all current demonstration projects offer PrEP education and/or counseling. PrEP support approaches generally fall into community-based, technology, monitoring, and integrated sexual health promotion approaches. Developing and implementing research that moves beyond simple correlates of either study product use or open-label PrEP adherence toward more comprehensive models of sociobehavioral and socioecological adherence determinants would greatly accelerate progress. Intervention research is needed to identify effective models of support for open-label PrEP adherence. PMID:24926036

Post-buckling of a pressured biopolymer spherical shell with the mode interaction

NASA Astrophysics Data System (ADS)

Zhang, Lei; Ru, C. Q.

2018-03-01

Imperfection sensitivity is essential for mechanical behaviour of biopolymer shells characterized by high geometric heterogeneity. The present work studies initial post-buckling and imperfection sensitivity of a pressured biopolymer spherical shell based on non-axisymmetric buckling modes and associated mode interaction. Our results indicate that for biopolymer spherical shells with moderate radius-to-thickness ratio (say, less than 30) and smaller effective bending thickness (say, less than 0.2 times average shell thickness), the imperfection sensitivity predicted based on the axisymmetric mode without the mode interaction is close to the present results based on non-axisymmetric modes with the mode interaction with a small (typically, less than 10%) relative errors. However, for biopolymer spherical shells with larger effective bending thickness, the maximum load an imperfect shell can sustain predicted by the present non-axisymmetric analysis can be significantly (typically, around 30%) lower than those predicted based on the axisymmetric mode without the mode interaction. In such cases, a more accurate non-axisymmetric analysis with the mode interaction, as given in the present work, is required for imperfection sensitivity of pressured buckling of biopolymer spherical shells. Finally, the implications of the present study to two specific types of biopolymer spherical shells (viral capsids and ultrasound contrast agents) are discussed.

Model of socio-cultural dimensions involved in adherence to antiretroviral therapy for HIV/AIDS in public health care centers in Chile.

PubMed

Stuardo Ávila, Valeria; Manriquez Urbina, Jose Manuel; Fajreldin Chuaqui, Valentina; Belmar Prieto, Julieta; Valenzuela Santibáñez, Victoria

2016-11-01

In Chile, over 14,000 adults are living with HIV receive antiretroviral therapy (HAART). Adequate adherence to HAART has a major impact on survival. There is little consensus on the causes of poor adherence, due to the unique and diverse sociocultural parameters involved in the issue. The objective of this study was to identify sociocultural dimensions that serve as barriers or facilitators to HAART adherence among persons living with HIV/AIDS (PLHIV) in Chile. A qualitative study design, with an exploratory followed by a descriptive phase was conducted. The study population consisted of adults living with HIV/AIDS, with and without HAART. A theoretical sample was designed and three gender profiles defined: women, men, and transwomen. Data collection methods included in-depth interviews by anthropologists in seven public health care centers for PLHIV. The model of sociocultural dimensions indicated that factors associated with family, expectations, gender/sexuality, affect, relationship with HIV, HAART, work, social support and networks, and stigma and discrimination influenced adherence, with different patterns among profiles. This study found that adherence is a dynamic category. It is crucial to consider sociocultural factors in developing strategies to improve HAART adherence.

Climate Informatics

NASA Technical Reports Server (NTRS)

Monteleoni, Claire; Schmidt, Gavin A.; Alexander, Francis J.; Niculescu-Mizil, Alexandru; Steinhaeuser, Karsten; Tippett, Michael; Banerjee, Arindam; Blumenthal, M. Benno; Ganguly, Auroop R.; Smerdon, Jason E.;

Letters in time and retinotopic space.

PubMed

Adelman, James S

2011-10-01

Various phenomena in tachistoscopic word identification and priming (WRODS and LTRS are confused with and prime WORDS and LETTERS) suggest that position-specific channels are not used in the processing of letters in words. Previous approaches to this issue have sought alternative matching rules because they have assumed that these phenomena reveal which stimuli are good but imperfect matches to a particular word-such imperfect matches being taken by the word recognition system as partial evidence for that word. The new Letters in Time and Retinotopic Space model (LTRS) makes the alternative assumption that these phenomena reveal the rates at which different features of the stimulus are extracted, because the stimulus is ambiguous when some features are missing from the percept. LTRS is successfully applied to tachistoscopic identification and form priming data with manipulations of duration and target-foil and prime-target relationships. © 2011 American Psychological Association

Enhancement of Buckling Load with the Use of Active Materials

NASA Technical Reports Server (NTRS)

Yuan, F. G.

2002-01-01

In this paper, active buckling control of a beam using piezoelectric materials is investigated. Under small deformation, mathematical models are developed to describe the behavior of the beams subjected to an axial compressive load with geometric imperfections and load eccentricities under piezoelectric force. Two types of supports, simply supported and clamped, of the beam with a partially bonded piezoelectric actuator are used to illustrate the concept. For the beam with load eccentricities and initial geometric imperfections, the load- carrying capacity can be significantly enhanced by counteracting moments from the piezoelectric actuator. For the single piezoelectric actuator, using static feedback closed-loop control, the first buckling load can be eliminated. In the case of initially straight beams, analytical solutions of the enhanced first critical buckling load due to the increase of bending stiffness by piezoelectric actuators are derived based on linearized buckling analysis.

Observer-Based Non-PDC Control for Networked T-S Fuzzy Systems With an Event-Triggered Communication.

PubMed

Peng, Chen; Ma, Shaodong; Xie, Xiangpeng

2017-02-07

This paper addresses the problem of an event-triggered non-parallel distribution compensation (PDC) control for networked Takagi-Sugeno (T-S) fuzzy systems, under consideration of the limited data transmission bandwidth and the imperfect premise matching membership functions. First, a unified event-triggered T-S fuzzy model is provided, in which: 1) a fuzzy observer with the imperfect premise matching is constructed to estimate the unmeasurable states of the studied system; 2) a fuzzy controller is designed following the same premise as the observer; and 3) an output-based event-triggering transmission scheme is designed to economize the restricted network resources. Different from the traditional PDC method, the synchronous premise between the fuzzy observer and the T-S fuzzy system are no longer needed in this paper. Second, by use of Lyapunov theory, a stability criterion and a stabilization condition are obtained for ensuring asymptotically stable of the studied system. On account of the imperfect premise matching conditions are well considered in the derivation of the above criteria, less conservation can be expected to enhance the design flexibility. Compared with some existing emulation-based methods, the controller gains are no longer required to be known a priori. Finally, the availability of proposed non-PDC design scheme is illustrated by the backing-up control of a truck-trailer system.

Exploring 'generative mechanisms' of the antiretroviral adherence club intervention using the realist approach: a scoping review of research-based antiretroviral treatment adherence theories.

PubMed

Mukumbang, Ferdinand C; Van Belle, Sara; Marchal, Bruno; van Wyk, Brian

2017-05-04

Poor retention in care and non-adherence to antiretroviral therapy (ART) continue to undermine the success of HIV treatment and care programmes across the world. There is a growing recognition that multifaceted interventions - application of two or more adherence-enhancing strategies - may be useful to improve ART adherence and retention in care among people living with HIV/AIDS. Empirical evidence shows that multifaceted interventions produce better results than interventions based on a singular perspective. Nevertheless, the bundle of mechanisms by which multifaceted interventions promote ART adherence are poorly understood. In this paper, we reviewed theories on ART adherence to identify candidate/potential mechanisms by which the adherence club intervention works. We searched five electronic databases (PubMed, EBSCOhost, CINAHL, PsycARTICLES and Google Scholar) using Medical Subject Headings (MeSH) terms. A manual search of citations from the reference list of the studies identified from the electronic databases was also done. Twenty-six articles that adopted a theory-guided inquiry of antiretroviral adherence behaviour were included for the review. Eleven cognitive and behavioural theories underpinning these studies were explored. We examined each theory for possible 'generative causality' using the realist evaluation heuristic (Context-Mechanism-Outcome) configuration, then, we selected candidate mechanisms thematically. We identified three major sets of theories: Information-Motivation-Behaviour, Social Action Theory and Health Behaviour Model, which explain ART adherence. Although they show potential in explaining adherence bebahiours, they fall short in explaining exactly why and how the various elements they outline combine to explain positive or negative outcomes. Candidate mechanisms indentified were motivation, self-efficacy, perceived social support, empowerment, perceived threat, perceived benefits and perceived barriers. Although these candidate mechanisms have been distilled from theories employed to explore adherence to ART in various studies, the theories by themselves do not provide an explanatory model of adherence based on the realist logic. The identified theories and candidate mechanisms offer possible generative mechanisms to explain how and why patients adhere (or not) to antiretroviral therapy. The study provides crucial insights to understanding how and why multifaceted adherence-enhancing interventions work (or not). These findings have implications for eliciting programme theories of group-based adherence interventions such as the adherence club intervention.

Hemodialysis patient beliefs by stage of fluid adherence.

PubMed

Welch, J L

2001-04-01

Fluid limitations are difficult for hemodialysis patients to follow, and factors related to fluid adherence are not well known. The primary purpose of this study, which was guided by the health belief model and the transtheoretical model for behavior change, was to determine whether differences exist in perceived benefits, barriers, susceptibility, seriousness, or self-efficacy among individuals in different stages of fluid adherence. In a cross-sectional descriptive design, 148 persons (mean age=53.9 years; 52% male) were interviewed using a structured format. Hemodialysis patients in the action/maintenance stage perceived significantly more benefits to fluid adherence than persons in the precontemplation stage. Persons who were in the action/maintenance stage perceived they were significantly more susceptible to pulmonary edema than persons in the contemplation stage. Stage-appropriate interventions may be needed to target specific beliefs about fluid adherence. Copyright 2001 John Wiley & Sons, Inc.

Applying the Information-Motivation-Behavioral Skills Model in Medication Adherence Among Thai Youth Living with HIV: A Qualitative Study

PubMed Central

Naar-King, Sylvie; Kaljee, Linda M.; Panthong, Apirudee; Koken, Juline A.; Bunupuradah, Torsak; Parsons, Jeffrey T.

2010-01-01

Abstract With disproportionately higher rates of HIV/AIDS among youth and increasing access to antiretroviral therapy (ART) in Thailand, there is a growing urgency in understanding the challenges to medication adherence confronting this population and in developing theory-based interventions to address these challenges. One potentially relevant model, the information-motivation-behavioral skills (IMB) model of adherence, was developed in Western settings characterized by a more individualistic culture in contrast to the more collectivistic culture of Thailand. We explored the application and adaptability of IMB on ART adherence among HIV-positive Thai youth through the analysis of qualitative data from a pilot motivational interviewing study. Twenty-two interview sessions from 10 HIV-positive Thai youth (17–24 years) were analyzed; 6 youth were on ART. Data support the utility of IMB as a potential framework for understanding ART adherence in this population. However, data indicate a consideration to expand the motivation construct of IMB to incorporate youths' perceived familial and social responsibilities and the need to adhere to medications for short- and long-term well-being of self, family, and society in a context of Buddhist values. These modifications to IMB could be relevant in other cultural settings with more collectivistic worldviews. PMID:21091238

The Impact of Stakeholder Preferences on Service User Adherence to Treatments for Schizophrenia and Metabolic Comorbidities.

PubMed

Poremski, Daniel; Sagayadevan, Vathsala D/O; Wang, Peizhi; Lum, Alvin; Subramaniam, Mythily; Ann, Chong Siow

2016-01-01

To determine how stakeholder opinions of treatments influence service user decisions to adhere to courses of actions necessary to treat metabolic conditions. Qualitative open-ended interviews were conducted with 20 service providers, 25 service users, and 9 caregivers. Grounded theory was used to generate an understanding that linked preferences of care with adherence to follow-up treatments. Participants spoke about several considerations when discussing adherence: Resource limitations were the predominant consideration. Social considerations such as stigma and support surfaced in caregiver and service-user interviews. The influence of symptoms, especially their absence could reduce adherence, and organizational considerations related to the opinions they had about the qualifications of professionals. A rational patient model partially organizes our findings, but emotional components related to stigma and the opinion of service providers do not fit well into such a model. If service providers do not consider components of the decision making process which fall outside of the rational patient model, they may incorrectly be leveraging suboptimal values to bring about adherence to treatment plans. Being sensitive to the values of service users and their caregivers may allow service providers to better act on points that may bring about change in non-compliant service users with schizophrenia and metabolic comorbidities.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duane, Greg; Tsonis, Anastasios; Kocarev, Ljupco

This collaborative reserach has several components but the main idea is that when imperfect copies of a given nonlinear dynamical system are coupled, they may synchronize for some set of coupling parameters. This idea is to be tested for several IPCC-like models each one with its own formulation and representing an “imperfect” copy of the true climate system. By computing the coupling parameters, which will lead the models to a synchronized state, a consensus on climate change simulations may be achieved.

Image Restoration by Spline Functions

DTIC Science & Technology

1976-08-31

motion degradation, over- determined model. 71 Figure 4-7. Singular values for motion blur. 72 Figure 5-1. Models for film-grain noise and filtering. 85...Figure 5-2. Filtering of signal dependent noisy images. 86 Figure 5-3. Filtering of image lines degraded by film- grain noise . 87 Figure 5-4...phenomena. Fhese phenomena include such imperfect imaging cir- cumstances as defocus, motion blur, optical aberrations, and noise D1I r> . Phe pioneers

Health behavior change: can genomics improve behavioral adherence?

PubMed

McBride, Colleen M; Bryan, Angela D; Bray, Molly S; Swan, Gary E; Green, Eric D

2012-03-01

The National Human Genome Research Institute recommends pursuing "genomic information to improve behavior change interventions" as part of its strategic vision for genomics. The limited effectiveness of current behavior change strategies may be explained, in part, by their insensitivity to individual variation in adherence responses. The first step in evaluating whether genomics can inform customization of behavioral recommendations is evidence reviews to identify adherence macrophenotypes common across behaviors and individuals that have genetic underpinnings. Conceptual models of how biological, psychological, and environmental factors influence adherence also are needed. Researchers could routinely collect biospecimens and standardized adherence measurements of intervention participants to enable understanding of genetic and environmental influences on adherence, to guide intervention customization and prospective comparative effectiveness studies.

Using Path Analysis to Evaluate the Healthcare Empowerment Model Among Persons Living with HIV for Antiretroviral Therapy Adherence

PubMed Central

Neilands, Torsten B.; Johnson, Mallory O.; Chen, Bing; Saberi, Parya

2016-01-01

Abstract Healthcare empowerment (HCE) is patient controlled and includes the process and state of being engaged, informed, collaborative, committed, and tolerant of uncertainty. Understanding psychosocial factors that impact HCE for persons living with HIV is critical for their treatment and care. A sample of 1494 male and female participants living with HIV in the United States with a mean age of 45.6 (standard deviation = 11.4) completed a one-time online survey about their demographic characteristics, social support, healthcare provider relationship, HIV treatment knowledge, perceived HIV-related stigma, lifetime trauma, depressive symptoms, HCE, and antiretroviral therapy (ART) adherence. A path analysis was conducted using structural equation modeling software to fit a theory-based model of HCE. Results included statistically significant direct pathways between depressive symptoms, healthcare provider relationship, lifetime trauma, and ART adherence, as well as between healthcare provider relationship, HIV treatment knowledge, and HCE. Specifically, ART adherence was positively linked to healthcare provider relationship and negatively linked to depressive symptoms and lifetime trauma. In addition, healthcare provider relationship and HIV treatment knowledge were positively associated with HCE. The indirect effects of healthcare provider relationship and HIV treatment knowledge on adherence through HCE were also significant. In particular, ART adherence was indirectly and positively affected by healthcare provider relationship and HIV treatment knowledge through HCE. Multi-level interventions are urgently needed to address the effects of these psychosocial factors on ART adherence. PMID:27849372

A model of parental distress and factors that mediate its link with parental monitoring of youth diabetes care, adherence, and glycemic control.

PubMed

Robinson, Elizabeth M; Weaver, Patrick; Chen, Rusan; Streisand, Randi; Holmes, Clarissa S

2016-12-01

Parental monitoring of adolescents' diabetes self-care is associated with better adherence and glycemic control (A1c). A number of parent-level factors are associated with higher levels of parental monitoring, including lower levels of parental distress (depressive symptoms, stress, anxiety), as well as higher levels of parental self-efficacy for diabetes management and authoritative parenting. Often studied in isolation, these factors may be best considered simultaneously as they are interrelated and are associated with parental monitoring and youth adherence. Structural equation modeling with a cross-sectional sample of 257 parent/youth (aged 11-14) dyads: (a) examined a broad model of parental factors (i.e., parental distress, parental diabetes self-efficacy, authoritative parenting), and (b) assessed their relation to parental monitoring, youth adherence, and A1c. Post hoc analyses of variance (ANOVAs) evaluated clinical implications of daily parental monitoring. Parental distress was not related directly to parental monitoring. Instead less distress related indirectly to more monitoring via higher parental self-efficacy and more authoritative parenting which, in turn, related to better adherence and A1c. Higher parental self-efficacy also related directly to better youth adherence and then to better A1c. Clinically, more parental monitoring related to more daily blood glucose checks and to better A1c (8.48% vs. 9.17%). A broad model of parent-level factors revealed more parental distress was linked only indirectly to less monitoring via lower parental self-efficacy and less authoritative parenting. Behaviorally, more parental monitoring related to better adherence and to clinically better A1c in adolescents. Further study of parent-level factors that relate to parental distress and monitoring of adherence appears warranted. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Can Mindfulness Training Improve Medication Adherence? Integrative Review of the Current Evidence and Proposed Conceptual Model.

PubMed

Salmoirago-Blotcher, Elena; Carey, Michael P

Medication adherence is a complex, multi-determined behavior that is often influenced by system- (e.g., cost), drug- (e.g., regimen complexity), and patient-related (e.g., depression) factors. System-level approaches (e.g., making medications more affordable) are critically important but do not address patient-level factors that can undermine adherence. In this paper, we identify patient-level determinants of non-adherence and discuss whether mindfulness-training approaches that target these determinants can help to improve adherence to medical treatment. We highlight two chronic medical conditions (viz., heart failure and HIV) where poor adherence is a significant concern, and examine the evidence regarding the use of mindfulness interventions to improve medication adherence in these two conditions. We also discuss the theoretical underpinnings of mindfulness training with respect to medication adherence, and conclude by suggesting directions for future research. Copyright © 2018 Elsevier Inc. All rights reserved.

Psychometrics of A New Questionnaire to Assess Glaucoma Adherence: The Glaucoma Treatment Compliance Assessment Tool (An American Ophthalmological Society Thesis)

PubMed Central

Mansberger, Steven L.; Sheppler, Christina R.; McClure, Tina M.; VanAlstine, Cory L.; Swanson, Ingrid L.; Stoumbos, Zoey; Lambert, William E.

2013-01-01

Purpose: To report the psychometrics of the Glaucoma Treatment Compliance Assessment Tool (GTCAT), a new questionnaire designed to assess adherence with glaucoma therapy. Methods: We developed the questionnaire according to the constructs of the Health Belief Model. We evaluated the questionnaire using data from a cross-sectional study with focus groups (n = 20) and a prospective observational case series (n=58). Principal components analysis provided assessment of construct validity. We repeated the questionnaire after 3 months for test-retest reliability. We evaluated predictive validity using an electronic dosing monitor as an objective measure of adherence. Results: Focus group participants provided 931 statements related to adherence, of which 88.7% (826/931) could be categorized into the constructs of the Health Belief Model. Perceived barriers accounted for 31% (288/931) of statements, cues-to-action 14% (131/931), susceptibility 12% (116/931), benefits 12% (115/931), severity 10% (91/931), and self-efficacy 9% (85/931). The principal components analysis explained 77% of the variance with five components representing Health Belief Model constructs. Reliability analyses showed acceptable Cronbach’s alphas (>.70) for four of the seven components (severity, susceptibility, barriers [eye drop administration], and barriers [discomfort]). Predictive validity was high, with several Health Belief Model questions significantly associated (P <.05) with adherence and a correlation coefficient (R2) of .40. Test-retest reliability was 90%. Conclusion: The GTCAT shows excellent repeatability, content, construct, and predictive validity for glaucoma adherence. A multisite trial is needed to determine whether the results can be generalized and whether the questionnaire accurately measures the effect of interventions to increase adherence. PMID:24072942

Rate-dependent elastic hysteresis during the peeling of pressure sensitive adhesives.

PubMed

Villey, Richard; Creton, Costantino; Cortet, Pierre-Philippe; Dalbe, Marie-Julie; Jet, Thomas; Saintyves, Baudouin; Santucci, Stéphane; Vanel, Loïc; Yarusso, David J; Ciccotti, Matteo

2015-05-07

The modelling of the adherence energy during peeling of Pressure Sensitive Adhesives (PSA) has received much attention since the 1950's, uncovering several factors that aim at explaining their high adherence on most substrates, such as the softness and strong viscoelastic behaviour of the adhesive, the low thickness of the adhesive layer and its confinement by a rigid backing. The more recent investigation of adhesives by probe-tack methods also revealed the importance of cavitation and stringing mechanisms during debonding, underlining the influence of large deformations and of the related non-linear response of the material, which also intervenes during peeling. Although a global modelling of the complex coupling of all these ingredients remains a formidable issue, we report here some key experiments and modelling arguments that should constitute an important step forward. We first measure a non-trivial dependence of the adherence energy on the loading geometry, namely through the influence of the peeling angle, which is found to be separable from the peeling velocity dependence. This is the first time to our knowledge that such adherence energy dependence on the peeling angle is systematically investigated and unambiguously demonstrated. Secondly, we reveal an independent strong influence of the large strain rheology of the adhesives on the adherence energy. We complete both measurements with a microscopic investigation of the debonding region. We discuss existing modellings in light of these measurements and of recent soft material mechanics arguments, to show that the adherence energy during peeling of PSA should not be associated to the propagation of an interfacial stress singularity. The relevant deformation mechanisms are actually located over the whole adhesive thickness, and the adherence energy during peeling of PSA should rather be associated to the energy loss by viscous friction and by rate-dependent elastic hysteresis.

Finite hedging in field theory models of interest rates

NASA Astrophysics Data System (ADS)

Baaquie, Belal E.; Srikant, Marakani

2004-03-01

We use path integrals to calculate hedge parameters and efficacy of hedging in a quantum field theory generalization of the Heath, Jarrow, and Morton [Robert Jarrow, David Heath, and Andrew Morton, Econometrica 60, 77 (1992)] term structure model, which parsimoniously describes the evolution of imperfectly correlated forward rates. We calculate, within the model specification, the effectiveness of hedging over finite periods of time, and obtain the limiting case of instantaneous hedging. We use empirical estimates for the parameters of the model to show that a low-dimensional hedge portfolio is quite effective.

A patient perspective of the impact of medication side effects on adherence: results of a cross-sectional nationwide survey of patients with schizophrenia.

PubMed

Dibonaventura, Marco; Gabriel, Susan; Dupclay, Leon; Gupta, Shaloo; Kim, Edward

2012-03-20

Antipsychotic medications often have a variety of side effects, however, it is not well understood how the presence of specific side effects correlate with adherence in a real-world setting. The aim of the current study was to examine the relationship between these variables among community-dwelling patients with schizophrenia. Data were analyzed from a 2007-2008 nationwide survey of adults who self-reported a diagnosis of schizophrenia and were currently using an antipsychotic medication (N = 876). The presence of side effects was defined as those in which the patient reported they were at least "somewhat bothered". Adherence was defined as a score of zero on the Morisky Medication Adherence Scale. To assess the relationship between side effects and adherence, individual logistic regression models were fitted for each side effect controlling for patient characteristics. A single logistic regression model assessed the relationship between side effect clusters and adherence. The relationships between adherence and health resource use were also examined. A majority of patients reported experiencing at least one side effect due to their medication (86.19%). Only 42.5% reported complete adherence. Most side effects were associated with a significantly reduced likelihood of adherence. When grouped as side effect clusters in a single model, extra pyramidal symptoms (EPS)/agitation (odds ratio (OR) = 0.57, p = 0.0007), sedation/cognition (OR = 0.70, p = 0.033), prolactin/endocrine (OR = 0.69, p = 0.0342), and metabolic side effects (OR = 0.64, p = 0.0079) were all significantly related with lower rates of adherence. Those who reported complete adherence to their medication were significantly less likely to report a hospitalization for a mental health reason (OR = 0.51, p = 0.0006), a hospitalization for a non-mental health reason (OR = 0.43, p = 0.0002), and an emergency room (ER) visit for a mental health reason (OR = 0.60, p = 0.008). Among patients with schizophrenia, medication side effects are highly prevalent and significantly associated with medication nonadherence. Nonadherence is significantly associated with increased healthcare resource use. Prevention, identification, and effective management of medication-induced side effects are important to maximize adherence and reduce health resource use in schizophrenia.

A patient perspective of the impact of medication side effects on adherence: results of a cross-sectional nationwide survey of patients with schizophrenia

PubMed Central

2012-01-01

Background Antipsychotic medications often have a variety of side effects, however, it is not well understood how the presence of specific side effects correlate with adherence in a real-world setting. The aim of the current study was to examine the relationship between these variables among community-dwelling patients with schizophrenia. Methods Data were analyzed from a 2007-2008 nationwide survey of adults who self-reported a diagnosis of schizophrenia and were currently using an antipsychotic medication (N = 876). The presence of side effects was defined as those in which the patient reported they were at least "somewhat bothered". Adherence was defined as a score of zero on the Morisky Medication Adherence Scale. To assess the relationship between side effects and adherence, individual logistic regression models were fitted for each side effect controlling for patient characteristics. A single logistic regression model assessed the relationship between side effect clusters and adherence. The relationships between adherence and health resource use were also examined. Results A majority of patients reported experiencing at least one side effect due to their medication (86.19%). Only 42.5% reported complete adherence. Most side effects were associated with a significantly reduced likelihood of adherence. When grouped as side effect clusters in a single model, extra pyramidal symptoms (EPS)/agitation (odds ratio (OR) = 0.57, p = 0.0007), sedation/cognition (OR = 0.70, p = 0.033), prolactin/endocrine (OR = 0.69, p = 0.0342), and metabolic side effects (OR = 0.64, p = 0.0079) were all significantly related with lower rates of adherence. Those who reported complete adherence to their medication were significantly less likely to report a hospitalization for a mental health reason (OR = 0.51, p = 0.0006), a hospitalization for a non-mental health reason (OR = 0.43, p = 0.0002), and an emergency room (ER) visit for a mental health reason (OR = 0.60, p = 0.008). Conclusions Among patients with schizophrenia, medication side effects are highly prevalent and significantly associated with medication nonadherence. Nonadherence is significantly associated with increased healthcare resource use. Prevention, identification, and effective management of medication-induced side effects are important to maximize adherence and reduce health resource use in schizophrenia. PMID:22433036

Joint longitudinal data analysis in detecting determinants of CD4 cell count change and adherence to highly active antiretroviral therapy at Felege Hiwot Teaching and Specialized Hospital, North-west Ethiopia (Amhara Region).

PubMed

Seyoum, Awoke; Ndlovu, Principal; Temesgen, Zewotir

2017-03-16

Adherence and CD4 cell count change measure the progression of the disease in HIV patients after the commencement of HAART. Lack of information about associated factors on adherence to HAART and CD4 cell count reduction is a challenge for the improvement of cells in HIV positive adults. The main objective of adopting joint modeling was to compare separate and joint models of longitudinal repeated measures in identifying long-term predictors of the two longitudinal outcomes: CD4 cell count and adherence to HAART. A longitudinal retrospective cohort study was conducted to examine the joint predictors of CD4 cell count change and adherence to HAART among HIV adult patients enrolled in the first 10 months of the year 2008 and followed-up to June 2012. Joint model was employed to determine joint predictors of two longitudinal response variables over time. Furthermore, the generalized linear mixed effect model had been used for specification of the marginal distribution, conditional to correlated random effect. A total of 792 adult HIV patients were studied to analyze the longitudinal joint model study. The result from this investigation revealed that age, weight, baseline CD4 cell count, ownership of cell phone, visiting times, marital status, residence area and level of disclosure of the disease to family members had significantly affected both outcomes. From the two-way interactions, time * owner of cell phone, time * sex, age * sex, age * level of education as well as time * level of education were significant for CD4 cell count change in the longitudinal data analysis. The multivariate joint model with linear predictor indicates that CD4 cell count change was positively correlated (p ≤ 0.0001) with adherence to HAART. Hence, as adherence to HAART increased, CD4 cell count also increased; and those patients who had significant CD4 cell count change at each visiting time had been encouraged to be good adherents. Joint model analysis was more parsimonious as compared to separate analysis, as it reduces type I error and subject-specific analysis improved its model fit. The joint model operates multivariate analysis simultaneously; and it has great power in parameter estimation. Developing joint model helps validate the observed correlation between the outcomes that have emerged from the association of intercepts. There should be a special attention and intervention for HIV positive adults, especially for those who had poor adherence and with low CD4 cell count change. The intervention may be important for pre-treatment counseling and awareness creation. The study also identified a group of patients who were with maximum risk of CD4 cell count change. It is suggested that this group of patients needs high intervention for counseling.

Work-Related Barriers and Facilitators to Antiretroviral Therapy Adherence in Persons Living with HIV Infection

PubMed Central

Torres-Madriz, Gilberto; Lerner, Debra; Ruthazer, Robin; Rogers, William H.; Wilson, Ira B.

2013-01-01

Little is known about how the structure of work affects adherence to HIV antiretroviral therapy. We surveyed participants in an adherence intervention study to learn more about job characteristics, including measures of psychological demand and control, and job accommodations. Adherence was assessed using the Medication Event Monitoring System (MEMS). Of 156 trial subjects, 69 were employed, and these 69 made 229 study visits. Psychological demands and control were unrelated to adherence, but the presence of workplace accommodations was significantly associated with adherence (p <0.05). In multivariable models adjusting for clustering, those who reported having received an accommodation were 12% more adherent than those who did not receive an accommodation. Adherence was unrelated to experiencing side effects affecting work performance. Having the ability to institute job accommodations was more important to adherence than the psychosocial structure of the work. These potential benefits of requesting modifications need to be weighed against the possible risks of workplace disclosure. PMID:20091340

Predicting Statistical Response and Extreme Events in Uncertainty Quantification through Reduced-Order Models

NASA Astrophysics Data System (ADS)

Qi, D.; Majda, A.

2017-12-01

A low-dimensional reduced-order statistical closure model is developed for quantifying the uncertainty in statistical sensitivity and intermittency in principal model directions with largest variability in high-dimensional turbulent system and turbulent transport models. Imperfect model sensitivity is improved through a recent mathematical strategy for calibrating model errors in a training phase, where information theory and linear statistical response theory are combined in a systematic fashion to achieve the optimal model performance. The idea in the reduced-order method is from a self-consistent mathematical framework for general systems with quadratic nonlinearity, where crucial high-order statistics are approximated by a systematic model calibration procedure. Model efficiency is improved through additional damping and noise corrections to replace the expensive energy-conserving nonlinear interactions. Model errors due to the imperfect nonlinear approximation are corrected by tuning the model parameters using linear response theory with an information metric in a training phase before prediction. A statistical energy principle is adopted to introduce a global scaling factor in characterizing the higher-order moments in a consistent way to improve model sensitivity. Stringent models of barotropic and baroclinic turbulence are used to display the feasibility of the reduced-order methods. Principal statistical responses in mean and variance can be captured by the reduced-order models with accuracy and efficiency. Besides, the reduced-order models are also used to capture crucial passive tracer field that is advected by the baroclinic turbulent flow. It is demonstrated that crucial principal statistical quantities like the tracer spectrum and fat-tails in the tracer probability density functions in the most important large scales can be captured efficiently with accuracy using the reduced-order tracer model in various dynamical regimes of the flow field with distinct statistical structures.

Socioeconomic Inequalities in Statin Adherence Under Universal Coverage: Does Sex Matter?

PubMed

Aarnio, Emma; Martikainen, Janne; Winn, Aaron N; Huupponen, Risto; Vahtera, Jussi; Korhonen, Maarit J

2016-11-01

Previous research shows that low socioeconomic position (SEP; especially low income) is associated with statin nonadherence. We investigated the relationship between SEP and statin adherence in a country with universal coverage using group-based trajectory modeling in addition to the proportion of days covered. Using data from Finnish healthcare registers, we identified 116 846 individuals, aged 45 to 75 years, who initiated statin therapy for primary prevention of cardiovascular disease. We measured adherence as proportion of days covered over an 18-month period since initiation and identified different adherence patterns based on monthly adherence with group-based trajectory modeling. When adjusted for age, marital status, residential area, clinical characteristics, and copayment, low SEP was associated with statin nonadherence (proportion of days covered <80%) among men (eg, lowest versus highest income quintile: odds ratio, 1.41; 95% confidence interval, 1.32-1.50; basic versus higher-degree education: odds ratio, 1.18; 95% confidence interval, 1.13-1.24; unemployment versus employment: odds ratio, 1.17; 95% confidence interval, 1.10-1.25). Among women, the corresponding associations were different ( P <0.001 for sex-by-income quintile, sex-by-education level, and sex-by-labor market status interactions) and mainly nonsignificant. Results based on adherence trajectories showed that men in low SEP were likely to belong to trajectories presenting a fast decline in adherence. Low SEP was associated with overall and rapidly increasing statin nonadherence among men. Conversely, in women, associations between SEP and nonadherence were weak and inconsistent. Group-based trajectory modeling provided insight into the dynamics of statin adherence and its association with SEP. © 2016 American Heart Association, Inc.

Fluctuation-induced forces in confined ideal and imperfect Bose gases

NASA Astrophysics Data System (ADS)

Diehl, H. W.; Rutkevich, Sergei B.

2017-06-01

Fluctuation-induced ("Casimir") forces caused by thermal and quantum fluctuations are investigated for ideal and imperfect Bose gases confined to d -dimensional films of size ∞d -1×D under periodic (P), antiperiodic (A), Dirichlet-Dirichlet (DD), Neumann-Neumann (NN), and Robin (R) boundary conditions (BCs). The full scaling functions ΥdBC(xλ=D /λth ,xξ=D /ξ ) of the residual reduced grand potential per area φres,dBC(T ,μ ,D ) =D-(d -1 )ΥdBC(xλ,xξ) are determined for the ideal gas case with these BCs, where λth and ξ are the thermal de Broglie wavelength and the bulk correlation length, respectively. The associated limiting scaling functions ΘdBC(xξ) ≡ΥdBC(∞ ,xξ) describing the critical behavior at the bulk condensation transition are shown to agree with those previously determined from a massive free O (2 ) theory for BC=P,A,DD,DN,NN . For d =3 , they are expressed in closed analytical form in terms of polylogarithms. The analogous scaling functions ΥdBC(xλ,xξ,c1D ,c2D ) and ΘdR(xξ,c1D ,c2D ) under the RBCs (∂z-c1) ϕ |z=0=(∂z+c2) ϕ | z =D=0 with c1≥0 and c2≥0 are also determined. The corresponding scaling functions Υ∞,d P(xλ,xξ) and Θ∞,d P(xξ) for the imperfect Bose gas are shown to agree with those of the interacting Bose gas with n internal degrees of freedom in the limit n →∞ . Hence, for d =3 , Θ∞,d P(xξ) is known exactly in closed analytic form. To account for the breakdown of translation invariance in the direction perpendicular to the boundary planes implied by free BCs such as DDBCs, a modified imperfect Bose gas model is introduced that corresponds to the limit n →∞ of this interacting Bose gas. Numerically and analytically exact results for the scaling function Θ∞,3 DD(xξ) therefore follow from those of the O (2 n ) ϕ4 model for n →∞ .

Fluctuation-induced forces in confined ideal and imperfect Bose gases.

PubMed

Diehl, H W; Rutkevich, Sergei B

2017-06-01

Fluctuation-induced ("Casimir") forces caused by thermal and quantum fluctuations are investigated for ideal and imperfect Bose gases confined to d-dimensional films of size ∞^{d-1}×D under periodic (P), antiperiodic (A), Dirichlet-Dirichlet (DD), Neumann-Neumann (NN), and Robin (R) boundary conditions (BCs). The full scaling functions Υ_{d}^{BC}(x_{λ}=D/λ_{th},x_{ξ}=D/ξ) of the residual reduced grand potential per area φ_{res,d}^{BC}(T,μ,D)=D^{-(d-1)}Υ_{d}^{BC}(x_{λ},x_{ξ}) are determined for the ideal gas case with these BCs, where λ_{th} and ξ are the thermal de Broglie wavelength and the bulk correlation length, respectively. The associated limiting scaling functions Θ_{d}^{BC}(x_{ξ})≡Υ_{d}^{BC}(∞,x_{ξ}) describing the critical behavior at the bulk condensation transition are shown to agree with those previously determined from a massive free O(2) theory for BC=P,A,DD,DN,NN. For d=3, they are expressed in closed analytical form in terms of polylogarithms. The analogous scaling functions Υ_{d}^{BC}(x_{λ},x_{ξ},c_{1}D,c_{2}D) and Θ_{d}^{R}(x_{ξ},c_{1}D,c_{2}D) under the RBCs (∂_{z}-c_{1})ϕ|_{z=0}=(∂_{z}+c_{2})ϕ|_{z=D}=0 with c_{1}≥0 and c_{2}≥0 are also determined. The corresponding scaling functions Υ_{∞,d}^{P}(x_{λ},x_{ξ}) and Θ_{∞,d}^{P}(x_{ξ}) for the imperfect Bose gas are shown to agree with those of the interacting Bose gas with n internal degrees of freedom in the limit n→∞. Hence, for d=3, Θ_{∞,d}^{P}(x_{ξ}) is known exactly in closed analytic form. To account for the breakdown of translation invariance in the direction perpendicular to the boundary planes implied by free BCs such as DDBCs, a modified imperfect Bose gas model is introduced that corresponds to the limit n→∞ of this interacting Bose gas. Numerically and analytically exact results for the scaling function Θ_{∞,3}^{DD}(x_{ξ}) therefore follow from those of the O(2n)ϕ^{4} model for n→∞.

Physicians' communication with patients about adherence to HIV medication in San Francisco and Copenhagen: a qualitative study using Grounded Theory

PubMed Central

Barfod, Toke S; Hecht, Frederick M; Rubow, Cecilie; Gerstoft, Jan

2006-01-01

Background Poor adherence is the main barrier to the effectiveness of HIV medication. The objective of this study was to explore and conceptualize patterns and difficulties in physicians' work with patients' adherence to HIV medication. No previous studies on this subject have directly observed physicians' behavior. Methods This is a qualitative, cross-sectional study. We used a Grounded Theory approach to let the main issues in physicians' work with patients' adherence emerge without preconceiving the focus of the study. We included physicians from HIV clinics in San Francisco, U.S.A. as well as from Copenhagen, Denmark. Physicians were observed during their clinical work and subsequently interviewed with a semi-structured interview guide. Notes on observations and transcribed interviews were analyzed with NVivo software. Results We enrolled 16 physicians from San Francisco and 18 from Copenhagen. When we discovered that physicians and patients seldom discussed adherence issues in depth, we made adherence communication and its barriers the focus of the study. The main patterns in physicians' communication with patients about adherence were similar in both settings. An important barrier to in-depth adherence communication was that some physicians felt it was awkward to explore the possibility of non-adherence if there were no objective signs of treatment failure, because patients could feel "accused." To overcome this awkwardness, some physicians consciously tried to "de-shame" patients regarding non-adherence. However, a recurring theme was that physicians often suspected non-adherence even when patients did not admit to have missed any doses, and physicians had difficulties handling this low believability of patient statements. We here develop a simple four-step, three-factor model of physicians' adherence communication. The four steps are: deciding whether to ask about adherence or not, pre-questioning preparations, phrasing the question, and responding to the patient's answer. The three factors/determinants are: physicians' perceptions of adherence, awkwardness, and believability. Conclusion Communication difficulties were a main barrier in physicians' work with patients' adherence to HIV medication. The proposed model of physicians' communication with patients about adherence – and the identification of awkwardness and believability as key issues – may aid thinking on the subject for use in clinical practice and future research. PMID:17144910

Physicians' communication with patients about adherence to HIV medication in San Francisco and Copenhagen: a qualitative study using Grounded Theory.

PubMed

Barfod, Toke S; Hecht, Frederick M; Rubow, Cecilie; Gerstoft, Jan

2006-12-04

Poor adherence is the main barrier to the effectiveness of HIV medication. The objective of this study was to explore and conceptualize patterns and difficulties in physicians' work with patients' adherence to HIV medication. No previous studies on this subject have directly observed physicians' behavior. This is a qualitative, cross-sectional study. We used a Grounded Theory approach to let the main issues in physicians' work with patients' adherence emerge without preconceiving the focus of the study. We included physicians from HIV clinics in San Francisco, U.S.A. as well as from Copenhagen, Denmark. Physicians were observed during their clinical work and subsequently interviewed with a semi-structured interview guide. Notes on observations and transcribed interviews were analyzed with NVivo software. We enrolled 16 physicians from San Francisco and 18 from Copenhagen. When we discovered that physicians and patients seldom discussed adherence issues in depth, we made adherence communication and its barriers the focus of the study. The main patterns in physicians' communication with patients about adherence were similar in both settings. An important barrier to in-depth adherence communication was that some physicians felt it was awkward to explore the possibility of non-adherence if there were no objective signs of treatment failure, because patients could feel "accused." To overcome this awkwardness, some physicians consciously tried to "de-shame" patients regarding non-adherence. However, a recurring theme was that physicians often suspected non-adherence even when patients did not admit to have missed any doses, and physicians had difficulties handling this low believability of patient statements. We here develop a simple four-step, three-factor model of physicians' adherence communication. The four steps are: deciding whether to ask about adherence or not, pre-questioning preparations, phrasing the question, and responding to the patient's answer. The three factors/determinants are: physicians' perceptions of adherence, awkwardness, and believability. Communication difficulties were a main barrier in physicians' work with patients' adherence to HIV medication. The proposed model of physicians' communication with patients about adherence--and the identification of awkwardness and believability as key issues--may aid thinking on the subject for use in clinical practice and future research.

"A Perfect Murder": An (Imperfect) School Theater Program Model

ERIC Educational Resources Information Center

Simon, Nicole S.; Grosso, Andrew

2009-01-01

Over the last five years, the Urban Assembly School for Law and Justice (SLJ), a new, small public high school in Brooklyn, and The Essentials, a professional theater company, have joined forces to offer a low-budget, high-quality, in-house afterschool theater program for SLJ students. Both SLJ and The Essentials were in nascent stages when the…

Scientific Reasoning in Early and Middle Childhood: The Development of Domain-General Evidence Evaluation, Experimentation, and Hypothesis Generation Skills

ERIC Educational Resources Information Center

Piekny, Jeanette; Maehler, Claudia

2013-01-01

According to Klahr's (2000, 2005; Klahr & Dunbar, 1988) Scientific Discovery as Dual Search model, inquiry processes require three cognitive components: hypothesis generation, experimentation, and evidence evaluation. The aim of the present study was to investigate (a) when the ability to evaluate perfect covariation, imperfect covariation,…

Accounting for imperfect detection in Hill numbers for biodiversity studies

USGS Publications Warehouse

Broms, Kristin M.; Hooten, Mevin B.; Fitzpatrick, Ryan M.

2015-01-01

The occupancy-based Hill number estimators are always at their asymptotic values (i.e. as if an infinite number of samples have been taken for the study region), therefore making it easy to compare biodiversity between different assemblages. In addition, the Hill numbers are computed as derived quantities within a Bayesian hierarchical model, allowing for straightforward inference.

Longitudinal Analysis of Adherence to First-Line Antiretroviral Therapy: Evidence of Treatment Sustainability from an Indian HIV Cohort.

PubMed

Shet, Anita; Kumarasamy, N; Poongulali, Selvamuthu; Shastri, Suresh; Kumar, Dodderi Sunil; Rewari, Bharath B; Arumugam, Karthika; Antony, Jimmy; De Costa, Ayesha; D'Souza, George

2016-01-01

Given the chronic nature of HIV infection and the need for life-long antiretroviral therapy (ART), maintaining long-term optimal adherence is an important strategy for maximizing treatment success. In order to understand better the dynamic nature of adherence behaviors in India where complex cultural and logistic features prevail, we assessed the patterns, trajectories and time-dependent predictors of adherence levels in relation to virological failure among individuals initiating first-line ART in India. Between July 2010 and August 2013, eligible ART-naïve HIV-infected individuals newly initiating first-line ART within the national program at three sites in southern India were enrolled and monitored for two years. ART included zidovudine/stavudine/tenofovir plus lamivudine plus nevirapine/efavirenz. Patients were assessed using clinical, laboratory and adherence parameters. Every three months, medication adherence was measured using pill count, and a structured questionnaire on adherence barriers was administered. Optimal adherence was defined as mean adherence ≥95%. Statistical analysis was performed using a bivariate and a multivariate model of all identified covariates. Adherence trends and determinants were modeled as rate ratios using generalized estimating equation analysis in a Poisson distribution. A total of 599 eligible ART-naïve patients participated in the study, and contributed a total of 921 person-years of observation time. Women constituted 43% and mean CD4 count prior to initiating ART was 192 cells/mm3. Overall mean adherence among all patients was 95.4%. The proportion of patients optimally adherent was 75.6%. Predictors of optimal adherence included older age (≥40 years), high school-level education and beyond, lower drug toxicity-related ART interruption, full disclosure, sense of satisfaction with one's own health and patient's perception of having good access to health-care services. Adherence was inversely proportional to virological failure (IRR 0.55, 95%CI 0.44-0.69 p<0.001). Drug toxicity and stigma-related barriers were significantly associated with virological failure, while forgetfulness was not associated with virological failure. Our study highlights the overall high level of medication adherence among individuals initiating ART within the Indian national program. Primary factors contributing towards poor adherence and subsequent virological failure in the proportion of individuals with poor adherence included drug toxicity, perceived stigma and poor access to health care services. Strategies that may contribute towards improved adherence include minimizing drug interruptions for medical reasons, use of newer ART regimens with better safety profiles and increasing access with more link ART centers that decentralize ART dispensing systems to individuals.

Pathways linking health literacy, health beliefs, and cognition to medication adherence in older adults with asthma.

PubMed

Soones, Tacara N; Lin, Jenny L; Wolf, Michael S; O'Conor, Rachel; Martynenko, Melissa; Wisnivesky, Juan P; Federman, Alex D

2017-03-01

Limited health literacy is associated with low adherence to asthma controller medications among older adults. We sought to describe the causal pathway linking health literacy to medication adherence by modeling asthma illness and medication beliefs as mediators. We recruited adults aged 60 years and older with asthma from hospital and community practices in New York, New York, and Chicago, Illinois. We measured health literacy and medication adherence using the Short Test of Functional Health Literacy in Adults and the Medication Adherence Rating Scale, respectively. We used validated instruments to assess asthma illness and medication beliefs. We assessed cognition using a cognitive battery. Using structural equation modeling, we modeled illness and medication beliefs as mediators of the relationship between health literacy and adherence while controlling for cognition. Our study included 433 patients with a mean age of 67 ± 6.8 years. The sample had 84% women, 31% non-Hispanic blacks, and 39% Hispanics. The 36% of patients with limited health literacy were more likely to have misconceptions about asthma (P < .001) and asthma medications (P < .001). Health literacy had a direct effect (β = 0.089; P < .001) as well as an indirect effect on adherence mediated by medications concerns (β = 0.033; P = .002). Neither medication necessity (β = 0.044; P = .138) nor illness beliefs (β = 0.007; P = .143) demonstrated a mediational role between health literacy and adherence. Interventions designed to improve asthma controller medication adherence in older adults may be enhanced by addressing concerns about medications in addition to using communication strategies appropriate for populations with limited health literacy and cognitive impairments. Copyright © 2016 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

Estimating indices of range shifts in birds using dynamic models when detection is imperfect

USGS Publications Warehouse

Clement, Matthew J.; Hines, James E.; Nichols, James D.; Pardieck, Keith L.; Ziolkowski, David J.

2016-01-01

There is intense interest in basic and applied ecology about the effect of global change on current and future species distributions. Projections based on widely used static modeling methods implicitly assume that species are in equilibrium with the environment and that detection during surveys is perfect. We used multiseason correlated detection occupancy models, which avoid these assumptions, to relate climate data to distributional shifts of Louisiana Waterthrush in the North American Breeding Bird Survey (BBS) data. We summarized these shifts with indices of range size and position and compared them to the same indices obtained using more basic modeling approaches. Detection rates during point counts in BBS surveys were low, and models that ignored imperfect detection severely underestimated the proportion of area occupied and slightly overestimated mean latitude. Static models indicated Louisiana Waterthrush distribution was most closely associated with moderate temperatures, while dynamic occupancy models indicated that initial occupancy was associated with diurnal temperature ranges and colonization of sites was associated with moderate precipitation. Overall, the proportion of area occupied and mean latitude changed little during the 1997–2013 study period. Near-term forecasts of species distribution generated by dynamic models were more similar to subsequently observed distributions than forecasts from static models. Occupancy models incorporating a finite mixture model on detection – a new extension to correlated detection occupancy models – were better supported and may reduce bias associated with detection heterogeneity. We argue that replacing phenomenological static models with more mechanistic dynamic models can improve projections of future species distributions. In turn, better projections can improve biodiversity forecasts, management decisions, and understanding of global change biology.

Imperfect asymmetry of life: earth microbial communities prefer D-lactate but can use L-lactate also.

PubMed

Moazeni, Faegheh; Zhang, Gaosen; Sun, Henry J

2010-05-01

Asymmetrical utilization of chiral compounds has been sought on Mars as evidence for biological activity. This method was recently validated in glucose. Earth organisms utilize D-glucose, not L-glucose, a perfect asymmetry. In this study, we tested the method in lactate and found utilization of both enantiomers. Soil-, sediment-, and lake-borne microbial communities prefer D-lactate but can consume L-lactate if given extra time to acclimate. This situation is termed imperfect asymmetry. Future life-detection mission investigators need to be aware of imperfect asymmetry so as not to miss relatively subtle signs of life.

On the Buckling of Imperfect Anisotropic Shells with Elastic Edge Supports Under Combined Loading Part I:. Pt. 1; Theory and Numerical Analysis

NASA Technical Reports Server (NTRS)

Arbocz, Johann; Hol, J. M. A. M.; deVries, J.

1998-01-01

A rigorous solution is presented for the case of stiffened anisotropic cylindrical shells with general imperfections under combined loading, where the edge supports are provided by symmetrical or unsymmetrical elastic rings. The circumferential dependence is eliminated by a truncated Fourier series. The resulting nonlinear 2-point boundary value problem is solved numerically via the "Parallel Shooting Method". The changing deformation patterns resulting from the different degrees of interaction between the given initial imperfections and the specified end rings are displayed. Recommendations are made as to the minimum ring stiffnesses required for optimal load carrying configurations.

Information, Learning, and Wage Rates in Low-Income Rural Areas.

ERIC Educational Resources Information Center

Foster, Andrew D.; Rosenzweig, Mark R.

1993-01-01

Survey data from the Philippines, India, and Pakistan show that imperfect information about worker productivity affects wage distribution across workers and over time; employers discriminate statistically regarding productivity and wages; calorie consumption affects productivity but is not rewarded; and (4) imperfect information can lead to…

The Imperfect Child in Early Twentieth-Century Russia

ERIC Educational Resources Information Center

Byford, Andy

2017-01-01

The article discusses the role that conceptualisations of child "imperfection" played in the rise and fall of Russian "child study" between the 1900s and the 1930s. Drawing on Georges Canguilhem's ideas on "the normal" and "the pathological", the article analyses practices centred on diagnosing subnormality…

Health Behavior Change: Can Genomics Improve Behavioral Adherence?

PubMed Central

Bryan, Angela D.; Bray, Molly S.; Swan, Gary E.; Green, Eric D.

2012-01-01

The National Human Genome Research Institute recommends pursuing “genomic information to improve behavior change interventions” as part of its strategic vision for genomics. The limited effectiveness of current behavior change strategies may be explained, in part, by their insensitivity to individual variation in adherence responses. The first step in evaluating whether genomics can inform customization of behavioral recommendations is evidence reviews to identify adherence macrophenotypes common across behaviors and individuals that have genetic underpinnings. Conceptual models of how biological, psychological, and environmental factors influence adherence also are needed. Researchers could routinely collect biospecimens and standardized adherence measurements of intervention participants to enable understanding of genetic and environmental influences on adherence, to guide intervention customization and prospective comparative effectiveness studies. PMID:22390502

Social support and conscientiousness in hemodialysis adherence.

PubMed

Moran, P J; Christensen, A J; Lawton, W J

1997-01-01

Previous conclusions regarding the role of social support in hemodialysis adherence are inconsistent, suggesting that other factors may moderate this relationship. Using the Five-Factor Model of Personality, we examined the hypothesis that conscientiousness would interact with social support in predicting fluid-intake and medication adherence in a sample of 56 chronic hemodialysis patients. Hierarchical regression analyses (controlling for demographic, clinical, and other personality variables) revealed a significant interaction between social support and conscientiousness. However, inconsistent with prediction, high support among patients with low conscientiousness was associated with poorer fluid-intake adherence, while support had little effect on fluid-intake adherence among high conscientiousness patients. No main or interactive effects were found for support or conscientiousness on a measure of medication adherence.

Declining occurrence and low colonization probability in freshwater mussel assemblages: A dynamic occurrence modeling approach

USGS Publications Warehouse

Pandolfo, Tamara J.; Kwak, Thomas J.; Cope, W. Gregory; Heise, Ryan J.; Nichols, Robert B.; Pacifici, Krishna

2017-01-01

Mussel monitoring data are abundant, but methods for analyzing long-term trends in these data are often uninformative or have low power to detect changes. We used a dynamic occurrence model, which accounted for imperfect species detection in surveys, to assess changes in species occurrence in a longterm data set (1986–2011) for the Tar River basin of North Carolina, USA. Occurrence of all species decreased steadily over the time period studied. Occurrence in 1986 ranged from 0.19 for Utterbackia imbecillis to 0.60 for Fusconaia masoni. Occurrence in 2010–2011 ranged from 0.10 for Lampsilis radiata to 0.40 for F. masoni. The maximum difference between occurrence in 1986 and 2011 was a decline of 0.30 for Alasmidonta undulata. Mean persistence for all species was high (0.97, 95% CI ¼ 0.95–0.99); however, mean colonization probability was very low (,0.01, 95% CI ¼ ,0.01–0.01). These results indicate that mussels persisted at sites already occupied but that they have not colonized sites where they had not occurred previously. Our findings highlight the importance of modeling approaches that incorporate imperfect detection in estimating species occurrence and revealing temporal trends to inform conservation planning.

Displaying contextual information reduces the costs of imperfect decision automation in rapid retasking of ISR assets.

PubMed

Rovira, Ericka; Cross, Austin; Leitch, Evan; Bonaceto, Craig

2014-09-01

The impact of a decision support tool designed to embed contextual mission factors was investigated. Contextual information may enable operators to infer the appropriateness of data underlying the automation's algorithm. Research has shown the costs of imperfect automation are more detrimental than perfectly reliable automation when operators are provided with decision support tools. Operators may trust and rely on the automation more appropriately if they understand the automation's algorithm. The need to develop decision support tools that are understandable to the operator provides the rationale for the current experiment. A total of 17 participants performed a simulated rapid retasking of intelligence, surveillance, and reconnaissance (ISR) assets task with manual, decision automation, or contextual decision automation differing in two levels of task demand: low or high. Automation reliability was set at 80%, resulting in participants experiencing a mixture of reliable and automation failure trials. Dependent variables included ISR coverage and response time of replanning routes. Reliable automation significantly improved ISR coverage when compared with manual performance. Although performance suffered under imperfect automation, contextual decision automation helped to reduce some of the decrements in performance. Contextual information helps overcome the costs of imperfect decision automation. Designers may mitigate some of the performance decrements experienced with imperfect automation by providing operators with interfaces that display contextual information, that is, the state of factors that affect the reliability of the automation's recommendation.

Adherence of older women with strength training and aerobic exercise

PubMed Central

Picorelli, Alexandra Miranda Assumpção; Pereira, Daniele Sirineu; Felício, Diogo Carvalho; Dos Anjos, Daniela Maria; Pereira, Danielle Aparecida Gomes; Dias, Rosângela Corrêa; Assis, Marcella Guimarães; Pereira, Leani Souza Máximo

2014-01-01

Background Participation of older people in a program of regular exercise is an effective strategy to minimize the physical decline associated with age. The purpose of this study was to assess adherence rates in older women enrolled in two different exercise programs (one aerobic exercise and one strength training) and identify any associated clinical or functional factors. Methods This was an exploratory observational study in a sample of 231 elderly women of mean age 70.5 years. We used a structured questionnaire with standardized tests to evaluate the relevant clinical and functional measures. A specific adherence questionnaire was developed by the researchers to determine motivators and barriers to exercise adherence. Results The adherence rate was 49.70% in the aerobic exercise group and 56.20% in the strength training group. Multiple logistic regression models for motivation were significant (P=0.003) for the muscle strengthening group (R2=0.310) and also significant (P=0.008) for the aerobic exercise group (R2=0.154). A third regression model for barriers to exercise was significant (P=0.003) only for the muscle strengthening group (R2=0.236). The present study shows no direct relationship between worsening health status and poor adherence. Conclusion Factors related to adherence with exercise in the elderly are multifactorial. PMID:24600212

Relations between cognitive status and medication adherence in patients treated for memory disorders

PubMed Central

Ownby, Raymond L.; Hertzog, Christopher; Czaja, Sara J.

2012-01-01

Medication adherence has been increasingly recognized as an important factor in elderly persons' health. Various studies have shown that medication non-adherence is associated with poor health status in this population. As part of a study of the effects of two interventions to promote medication adherence in patients treated for memory problems, information on medication adherence and cognitive status was collected at 3-month intervals. Twenty-seven participants (16 men, 11 women, age 71–92 years) were assigned to control or treatment conditions and adherence was evaluated with an electronic monitoring device. Cognitive status was evaluated at 3-month intervals beginning in April of 2003 and continuing through September of 2006. We have previously reported on the effectiveness of these interventions to promote adherence. In this paper, we examine the relations of cognitive status and adherence over time using a partial least squares path model in order to evaluate the extent to which adherence to cholinesterase medications was related to cognitive status. Adherence predicted cognitive status at later time points while cognition did not, in general, predict adherence. Results thus suggest that interventions to ensure high levels of medication adherence may be important for maintaining cognitive function in affected elderly people. PMID:24575293

Personality and patient adherence: correlates of the five-factor model in renal dialysis.

PubMed

Christensen, A J; Smith, T W

1995-06-01

The five-factor taxonomy of personality traits has received increasing attention in the literature regarding personality correlates of health outcomes and behaviors. We examined the association of the five NEO Five-Factor Inventory dimensions to medical regimen adherence in a sample of 72 renal dialysis patients. Results indicated that Conscientiousness (Dimension III) is a five-factor trait significantly associated with adherence to the medication regimen. No other NEO-FFI dimension was significantly associated with patient adherence.

Autocorrelated residuals in inverse modelling of soil hydrological processes: a reason for concern or something that can safely be ignored?

NASA Astrophysics Data System (ADS)

Scharnagl, Benedikt; Durner, Wolfgang

2013-04-01

Models are inherently imperfect because they simplify processes that are themselves imperfectly known and understood. Moreover, the input variables and parameters needed to run a model are typically subject to various sources of error. As a consequence of these imperfections, model predictions will always deviate from corresponding observations. In most applications in soil hydrology, these deviations are clearly not random but rather show a systematic structure. From a statistical point of view, this systematic mismatch may be a reason for concern because it violates one of the basic assumptions made in inverse parameter estimation: the assumption of independence of the residuals. But what are the consequences of simply ignoring the autocorrelation in the residuals, as it is current practice in soil hydrology? Are the parameter estimates still valid even though the statistical foundation they are based on is partially collapsed? Theory and practical experience from other fields of science have shown that violation of the independence assumption will result in overconfident uncertainty bounds and that in some cases it may lead to significantly different optimal parameter values. In our contribution, we present three soil hydrological case studies, in which the effect of autocorrelated residuals on the estimated parameters was investigated in detail. We explicitly accounted for autocorrelated residuals using a formal likelihood function that incorporates an autoregressive model. The inverse problem was posed in a Bayesian framework, and the posterior probability density function of the parameters was estimated using Markov chain Monte Carlo simulation. In contrast to many other studies in related fields of science, and quite surprisingly, we found that the first-order autoregressive model, often abbreviated as AR(1), did not work well in the soil hydrological setting. We showed that a second-order autoregressive, or AR(2), model performs much better in these applications, leading to parameter and uncertainty estimates that satisfy all the underlying statistical assumptions. For theoretical reasons, these estimates are deemed more reliable than those estimates based on the neglect of autocorrelation in the residuals. In compliance with theory and results reported in the literature, our results showed that parameter uncertainty bounds were substantially wider if autocorrelation in the residuals was explicitly accounted for, and also the optimal parameter vales were slightly different in this case. We argue that the autoregressive model presented here should be used as a matter of routine in inverse modeling of soil hydrological processes.

Mouse Models in Bone Marrow Transplantation and Adoptive Cellular Therapy

PubMed Central

Arber, Caroline; Brenner, Malcolm K.; Reddy, Pavan

2014-01-01

Mouse models of transplantation have been indispensable to the development of bone marrow transplantation (BMT). Their role in the generation of basic science knowledge is invaluable and is subject to discussion below. However, this article focuses on the direct role and relevance of mouse models towards the clinical development and advances in BMT and adoptive T-cell therapy for human diseases. The authors aim to present a thoughtful perspective on the pros and cons of mouse models while noting that despite imperfections these models are obligatory for the development of science-based medicine. PMID:24216170

Neuronal Mechanism for Compensation of Longitudinal Chromatic Aberration-Derived Algorithm.

PubMed

Barkan, Yuval; Spitzer, Hedva

2018-01-01

The human visual system faces many challenges, among them the need to overcome the imperfections of its optics, which degrade the retinal image. One of the most dominant limitations is longitudinal chromatic aberration (LCA), which causes short wavelengths (blue light) to be focused in front of the retina with consequent blurring of the retinal chromatic image. The perceived visual appearance, however, does not display such chromatic distortions. The intriguing question, therefore, is how the perceived visual appearance of a sharp and clear chromatic image is achieved despite the imperfections of the ocular optics. To address this issue, we propose a neural mechanism and computational model, based on the unique properties of the S -cone pathway. The model suggests that the visual system overcomes LCA through two known properties of the S channel: (1) omitting the contribution of the S channel from the high-spatial resolution pathway (utilizing only the L and M channels). (b) Having large and coextensive receptive fields that correspond to the small bistratified cells. Here, we use computational simulations of our model on real images to show how integrating these two basic principles can provide a significant compensation for LCA. Further support for the proposed neuronal mechanism is given by the ability of the model to predict an enigmatic visual phenomenon of large color shifts as part of the assimilation effect.

Neuronal Mechanism for Compensation of Longitudinal Chromatic Aberration-Derived Algorithm

PubMed Central

Barkan, Yuval; Spitzer, Hedva

2018-01-01

The human visual system faces many challenges, among them the need to overcome the imperfections of its optics, which degrade the retinal image. One of the most dominant limitations is longitudinal chromatic aberration (LCA), which causes short wavelengths (blue light) to be focused in front of the retina with consequent blurring of the retinal chromatic image. The perceived visual appearance, however, does not display such chromatic distortions. The intriguing question, therefore, is how the perceived visual appearance of a sharp and clear chromatic image is achieved despite the imperfections of the ocular optics. To address this issue, we propose a neural mechanism and computational model, based on the unique properties of the S-cone pathway. The model suggests that the visual system overcomes LCA through two known properties of the S channel: (1) omitting the contribution of the S channel from the high-spatial resolution pathway (utilizing only the L and M channels). (b) Having large and coextensive receptive fields that correspond to the small bistratified cells. Here, we use computational simulations of our model on real images to show how integrating these two basic principles can provide a significant compensation for LCA. Further support for the proposed neuronal mechanism is given by the ability of the model to predict an enigmatic visual phenomenon of large color shifts as part of the assimilation effect. PMID:29527525

Validating Hydrodynamic Growth in National Ignition Facility Implosions

NASA Astrophysics Data System (ADS)

Peterson, J. Luc

2014-10-01

The hydrodynamic growth of capsule imperfections can threaten the success of inertial confinement fusion implosions. Therefore, it is important to design implosions that are robust to hydrodynamic instabilities. However, the numerical simulation of interacting Rayleigh-Taylor and Richtmyer-Meshkov growth in these implosions is sensitive to modeling uncertainties such as radiation drive and material equations of state, the effects of which are especially apparent at high mode number (small perturbation wavelength) and high convergence ratio (small capsule radius). A series of validation experiments were conducted at the National Ignition Facility to test the ability to model hydrodynamic growth in spherically converging ignition-relevant implosions. These experiments on the Hydro-Growth Radiography platform constituted direct measurements of the growth of pre-imposed imperfections up to Legendre mode 160 and a convergence ratio of greater than four using two different laser drives: a ``low-foot'' drive used during the National Ignition Campaign and a larger adiabat ``high-foot'' drive that is modeled to be relatively more robust to ablation front hydrodynamic growth. We will discuss these experiments and how their results compare to numerical simulations and analytic theories of hydrodynamic growth, as well as their implications for the modeling of future designs. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Interventions to Improve Medication Adherence among Older Adults: Meta-Analysis of Adherence Outcomes among Randomized Controlled Trials

ERIC Educational Resources Information Center

Conn, Vicki S.; Hafdahl, Adam R.; Cooper, Pamela S.; Ruppar, Todd M.; Mehr, David R.; Russell, Cynthia L.

2009-01-01

Purpose: This study investigated the effectiveness of interventions to improve medication adherence (MA) in older adults. Design and Methods: Meta-analysis was used to synthesize results of 33 published and unpublished randomized controlled trials. Random-effects models were used to estimate overall mean effect sizes (ESs) for MA, knowledge,…

How Do Implementation Efforts Relate to Program Adherence? Examining the Role of Organizational, Implementer, and Program Factors

ERIC Educational Resources Information Center

Dariotis, Jacinda K.; Bumbarger, Brian K.; Duncan, Larissa G.; Greenberg, Mark T.

2008-01-01

Widespread replications of evidence-based prevention programs (EBPPs) prompt prevention scientists to examine program implementation adherence in real world settings. Based on Chen's model (1990), we identified five key factors of the implementation system and assessed which characteristics related to program adherence. The sample included 32…

Looking for trouble: Adherence to late-effects surveillance among childhood cancer survivors.

PubMed

Reppucci, Marina L; Schleien, Charles L; Fish, Jonathan D

2017-02-01

Childhood cancer survivors (CCSs) are at high risk of morbidity and mortality from long-term complications of their cancer treatment. The Children's Oncology Group developed screening guidelines to enable the early identification of and intervention for late effects of cancer treatment. There is a paucity of data on the adherence of CCSs to screening recommendations. A retrospective analysis of medical records to evaluate the rate of adherence of CCSs to the personalized, risk-based recommendations provided to them in the context of a structured long-term follow-up program over a 3-year period. Two hundred eighty-six CCSs visited the survivorship clinic 542 times during the 3-year study period. The overall rate of adherence to recommended screening was 74.2%. Using a univariate model and greater age at diagnosis and at screening recommendation were associated with decreased screening adherence. Gender, cancer diagnosis, radiation therapy, anthracycline exposure, and hematopoietic stem cell transplant were not significantly associated with adherence. In a multivariate model, age over 18 years at the time of the visit was significantly associated with decreased adherence (P < 0.0329) (odds ratio: 1.53, 95% confidence interval: 1.04-2.25). Adherence to recommended screening tests is suboptimal among CCSs, with lower rates of adherence in CCSs older than 18 years of age compared with those younger than 18 years of age. Given the morbidity and mortality from the late effects of therapy among young adult CCSs, it is critically important to identify and remove barriers to late-effects screening among CCSs. © 2016 Wiley Periodicals, Inc.

Impact of increasing adherence to disease-modifying therapies on healthcare resource utilization and direct medical and indirect work loss costs for patients with multiple sclerosis.

PubMed

Yermakov, Sander; Davis, Matthew; Calnan, Michaela; Fay, Monica; Cox-Buckley, Brieana; Sarda, Sujata; Duh, Mei Sheng; Iyer, Ravi

2015-01-01

To estimate the effect of adherence to disease-modifying therapies (DMTs) among patients with multiple sclerosis (MS) on healthcare resource utilization (HRU) and costs, and model the impact of a 10 percentage point increase in adherence on these outcomes. Employed patients, 18-64 years old, with ≥2 MS diagnoses and ≥1 DMT claim during January 1, 2002 to September 30, 2012 were identified from a large commercially-insured US claims database. Adherence was measured as proportion of days covered (PDC) during follow-up. Multivariate regression analyses were conducted to estimate the effect of adherence on HRU related to urgent care (i.e., inpatient or emergency room visit), days of work loss, direct medical cost, and indirect work loss costs. Model coefficients were used to evaluate the impact of a 10 percentage point increase in adherence on the outcomes. A total of 1510 patients were included (mean age = 43.4 years, 64% female). Patients with higher adherence had lower HRU, fewer days of work loss, and lower direct and indirect costs. A 10 percentage point increase in adherence significantly decreased the likelihood of an inpatient or emergency room visit by 9-19%, days of work loss by 3-8%, and direct and indirect costs by 3-5%, depending on the follow-up period (all p < 0.01). Increasing DMT adherence was found to significantly decrease urgent-care HRU, days of work loss, and direct and indirect costs among patients with MS.

Quantum biological channel modeling and capacity calculation.

PubMed

Djordjevic, Ivan B

2012-12-10

Quantum mechanics has an important role in photosynthesis, magnetoreception, and evolution. There were many attempts in an effort to explain the structure of genetic code and transfer of information from DNA to protein by using the concepts of quantum mechanics. The existing biological quantum channel models are not sufficiently general to incorporate all relevant contributions responsible for imperfect protein synthesis. Moreover, the problem of determination of quantum biological channel capacity is still an open problem. To solve these problems, we construct the operator-sum representation of biological channel based on codon basekets (basis vectors), and determine the quantum channel model suitable for study of the quantum biological channel capacity and beyond. The transcription process, DNA point mutations, insertions, deletions, and translation are interpreted as the quantum noise processes. The various types of quantum errors are classified into several broad categories: (i) storage errors that occur in DNA itself as it represents an imperfect storage of genetic information, (ii) replication errors introduced during DNA replication process, (iii) transcription errors introduced during DNA to mRNA transcription, and (iv) translation errors introduced during the translation process. By using this model, we determine the biological quantum channel capacity and compare it against corresponding classical biological channel capacity. We demonstrate that the quantum biological channel capacity is higher than the classical one, for a coherent quantum channel model, suggesting that quantum effects have an important role in biological systems. The proposed model is of crucial importance towards future study of quantum DNA error correction, developing quantum mechanical model of aging, developing the quantum mechanical models for tumors/cancer, and study of intracellular dynamics in general.

Integrating occupancy models and structural equation models to understand species occurrence

PubMed Central

Joseph, Maxwell B.; Preston, Daniel L.; Johnson, Pieter T. J.

2016-01-01

Understanding the drivers of species occurrence is a fundamental goal in basic and applied ecology. Occupancy models have emerged as a popular approach for inferring species occurrence because they account for problems associated with imperfect detection in field surveys. Current models, however, are limited because they assume covariates are independent (i.e., indirect effects do not occur). Here, we combined structural equation and occupancy models to investigate complex influences on species occurrence while accounting for imperfect detection. These two methods are inherently compatible because they both provide means to make inference on latent or unobserved quantities based on observed data. Our models evaluated the direct and indirect roles of cattle grazing, water chemistry, vegetation, nonnative fishes, and pond permanence on the occurrence of six pond-breeding amphibians, two of which are threatened: the California tiger salamander (Ambystoma californiense), and the California red-legged frog (Rana draytonii). While cattle had strong effects on pond vegetation and water chemistry, their overall effects on amphibian occurrence were small compared to the consistently negative effects of nonnative fish. Fish strongly reduced occurrence probabilities for four of five native amphibians, including both species of conservation concern. These results could help to identify drivers of amphibian declines and to prioritize strategies for amphibian conservation. More generally, this approach facilitates a more mechanistic representation of ideas about the causes of species distributions in space and time. As shown here, occupancy modeling and structural equation modeling are readily combined, and bring rich sets of techniques that may provide unique theoretical and applied insights into basic ecological questions. PMID:27197402

Qualitative study to conceptualise a model of interprofessional collaboration between pharmacists and general practitioners to support patients' adherence to medication

PubMed Central

Rathbone, Adam P; Mansoor, Sarab M; Krass, Ines; Hamrosi, Kim; Aslani, Parisa

2016-01-01

Objectives Pharmacists and general practitioners (GPs) face an increasing expectation to collaborate interprofessionally on a number of healthcare issues, including medication non-adherence. This study aimed to propose a model of interprofessional collaboration within the context of identifying and improving medication non-adherence in primary care. Setting Primary care; Sydney, Australia. Participants 3 focus groups were conducted with pharmacists (n=23) and 3 with GPs (n=22) working in primary care. Primary and secondary outcome measures Qualitative investigation of GP and pharmacist interactions with each other, and specifically around supporting their patients’ medication adherence. Audio-recordings were transcribed verbatim and transcripts thematically analysed using a combination of manual and computer coding. Results 3 themes pertaining to interprofessional collaboration were identified (1) frequency, (2) co-collaborators and (3) nature of communication which included 2 subthemes (method of communication and type of communication). While the frequency of interactions was low, the majority were conducted by telephone. Interactions, especially those conducted face-to-face, were positive. Only a few related to patient non-adherence. The findings are positioned within contemporary collaborative theory and provide an accessible introduction to models of interprofessional collaboration. Conclusions This work highlighted that successful collaboration to improve medication adherence was underpinned by shared paradigmatic perspectives and trust, constructed through regular, face-to-face interactions between pharmacists and GPs. PMID:26983948

Compliance to follow up and adherence to medication in hypertensive patients in an urban informal settlement in Kenya: comparison of three models of care.

PubMed

Kuria, Ng'endo; Reid, Anthony; Owiti, Philip; Tweya, Hannock; Kibet, Caleb Kipkurui; Mbau, Lilian; Manzi, Marcel; Murunga, Victor; Namusonge, Tecla; Kibachio, Joseph

2018-05-19

To determine and compare, among three models of care, compliance to scheduled clinic appointments and adherence to anti-hypertensive medication of patients in an informal settlement of Kibera, Kenya. Routinely collected patient data were used from three health facilities, six walkway clinics and one weekend/church clinic. Patients were eligible if they had received hypertension care for more than six months. Compliance with clinic appointments and self-reported adherence to medication were determined from clinic records and compared using the Chi-square test. Univariate and multivariate logistic regression models estimated the odds of overall adherence to medication. 785 patients received hypertension treatment eligible for analysis, of whom two-thirds were women. Between them, there were 5879 clinic visits with an overall compliance to appointments of 63%. Compliance was high in the health facilities and walkway clinics but men were more likely to attend the weekend/church clinics. Self-reported adherence to medication by those complying with scheduled clinic visits was 94%. Patients in the walkway clinics were two times more likely to adhere to anti-hypertensive medication than patients at the health facility (OR 1.97, 95%CI 1.25-3.10). Walkway clinics outperformed health facilities and weekend clinics. Use of multiple sites for the management of hypertensive patients led to good compliance with scheduled clinic visits and very good self-reported adherence to medication in a low-resource setting. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Population trends influence species ability to track climate change

Treesearch

Joel Ralston; William V. DeLuca; Richard E. Feldman; David I. King

2016-01-01

Shifts of distributions have been attributed to species tracking their fundamental climate niches through space. However, several studies have now demonstrated that niche tracking is imperfect, that species' climate niches may vary with population trends, and that geographic distributions may lag behind rapid climate change. These reports of imperfect niche...

Evaluation Strategies in Financial Education: Evaluation with Imperfect Instruments

ERIC Educational Resources Information Center

Robinson, Lauren; Dudensing, Rebekka; Granovsky, Nancy L.

2016-01-01

Program evaluation often suffers due to time constraints, imperfect instruments, incomplete data, and the need to report standardized metrics. This article about the evaluation process for the Wi$eUp financial education program showcases the difficulties inherent in evaluation and suggests best practices for assessing program effectiveness. We…

Bell's Paradox under Different Capital Market Regimes.

ERIC Educational Resources Information Center

Kang, Johan Moonwon

1993-01-01

In 1984 "Economics of Education Review" paper, E. Bell indicates that, when capital markets are imperfect in a certain sense, demand for education may not always be directly related with present net value of education. This study shows Bell's paradox is possible under the alternative definitions of capital market imperfections and…

Obligatory Grammatical Categories and the Expression of Temporal Events

ERIC Educational Resources Information Center

Winskel, Heather; Luksaneeyanawin, Sudaporn

2009-01-01

Thai has imperfective aspectual morphemes that are not obligatory in usage, whereas English has obligatory grammaticized imperfective aspectual marking on the verb. Furthermore, Thai has verb final deictic-path verbs that form a closed class set. The current study investigated if obligatoriness of these grammatical categories in Thai and English…

Association between adherence measurements of metoprolol and health care utilization in older patients with heart failure

PubMed Central

Tu, Wanzhu; Morris, Andrew B.; Li, Jingjin; Wu, Jingwei; Young, James; Brater, D. Craig; Murray, Michael D.

2008-01-01

Objective Data from electronic dosing monitors and published pharmacokinetic parameters were used to derive medication adherence measures for immediate-release metoprolol and examine their association with health care utilization of outpatients aged 50 years or older with heart failure. Methods We used a 1-compartment model and published population pharmacokinetic parameters to estimate mean plasma metoprolol concentrations for patients treated for 6 to 12 months. In the absence of directly measured plasma concentrations, we calculated the intended mean plasma concentration (Cp′ave) under the assumption of perfect adherence to the prescribed dose and frequency of administration. Projected mean plasma concentrations (Cpave) were estimated by use of data from recorded dosing times. In addition to taking adherence (percentage of dose taken) and scheduling adherence (percentage of doses taken on schedule), we calculated the deviation from the intended exposure (ΔCpave = Cp′ave − Cpave) and the proportion of intended exposure achieved by the patient (Cpave/Cp′ave). We assessed the association between the adherence measures and the numbers of emergency department visits and hospital admissions experienced by the patients. Results Patients (N = 80) were aged 62 ± 8 years. Mean ΔCpave and Cpave/Cp′ave were 7.9 ng/mL (SD, 10.7) and 0.6 (SD, 0.3), respectively. Log-linear models adjusted for patient functional status indicated that greater deviation from the intended metoprolol exposure (ΔCpave) was associated with increased numbers of emergency department visits (P < .0001) and hospital admissions (P < .0001). A higher proportion of intended exposure (Cpave/Cp′ave) corresponded to a reduced number of emergency department visits (P = .0204) and hospital admissions (P = .0093). Taking adherence was univariately associated with both emergency department visits and hospital visits (P < .0001 and P = .0010, respectively). Scheduling adherence was associated with the number of emergency department visits (P = .0181) but not with the number of hospital admissions (P = .1602). Model selection procedures consistently chose the proposed measures over taking adherence and scheduling adherence. Conclusion Deviation from the intended exposure and proportion of intended exposure achieved by the patient are valid adherence measures for immediate-release metoprolol and are associated with health care utilization. The potential utility of these measures for other β-adrenergic antagonists and perhaps other cardiovascular drugs should be investigated. PMID:15735613

A theoretical approach to medication adherence for children and youth with psychiatric disorders.

PubMed

Charach, Alice; Volpe, Tiziana; Boydell, Katherine M; Gearing, Robin E

2008-01-01

This article provides a theoretical review of treatment adherence for children and youth with psychiatric disorders where pharmacological agents are first-line interventions. Four empirically based models of health behavior are reviewed and applied to the sparse literature about medication adherence for children with attention-deficit/hyperactivity disorder and young people with first-episode psychosis. Three qualitative studies of medication use are summarized, and details from the first-person narratives are used to illustrate the theoretical models. These studies indicate, when taken together, that the clinical approach to addressing poor medication adherence in children and youth with psychiatric disorders should be guided by more than one theoretical model. Mental health experts should clarify beliefs, address misconceptions, and support exploration of alternative treatment options unless contraindicated. Recognizing the larger context of the family, allowing time for parents and children to change their attitudes, and offering opportunities for easy access to medication in the future are important ways of respecting patient preferences, while steering them toward best-evidence interventions. Future research using qualitative methods of inquiry to investigate parent, child, and youth experiences of mental health interventions should identify effective ways to improve treatment adherence.

Remote Monitoring to Reduce Heart Failure Readmissions.

PubMed

Emani, Sitaramesh

2017-02-01

Rehospitalization for heart failure remains a challenge in the treatment of affected patients. The ability to remotely monitor patients for worsening heart failure may provide an avenue through which therapeutic interventions can be made to prevent a rehospitalization. Available data on remote monitoring to reduce heart failure rehospitalizations are reviewed within. Strategies to reduce readmissions include clinical telemonitoring, bioimpedance changes, biomarkers, and remote hemodynamic monitoring. Telemonitoring is readily available, but has low sensitivity and adherence. No data exist to demonstrate the efficacy of this strategy in reducing admissions. Bioimpedance offers improved sensitivity compared to telemonitoring, but has not demonstrated an ability to reduce hospitalizations and is currently limited to those patients who have separate indications for an implantable device. Biomarker levels have shown variable results in the ability to reduce hospitalizations and remain without definitive proof supporting their utilization. Remote hemodynamic monitoring has shown the strongest ability to reduce heart failure readmissions and is currently approved for this purpose. However, remote hemodynamic monitoring requires an invasive procedure and may not be cost-effective. All currently available strategies to reduce hospitalizations with remote monitoring have drawbacks and challenges. Remote hemodynamic monitoring is currently the most efficacious based on data, but is not without its own imperfections.

Differentiated models of care for postpartum women on antiretroviral therapy in Cape Town, South Africa: a cohort study.

PubMed

Myer, Landon; Iyun, Victoria; Zerbe, Allison; Phillips, Tamsin K; Brittain, Kirsty; Mukonda, Elton; Allerton, Joanna; Kalombo, Cathy D; Nofemela, Andile; Abrams, Elaine J

2017-07-21

The numbers of women initiating lifelong antiretroviral therapy (ART) during pregnancy and postpartum is increasing rapidly, presenting a burden on health systems and an urgent need for scalable models of care for this population. In a pilot project, we referred postpartum women who initiated ART during pregnancy to a community-based model of differentiated ART services. Eligible women (on ART for at least 3 months with viral load (VL)<1000 copies/mL) were offered a choice of two ART models of care: (i) referral to an existing system of community-based 'adherence clubs', operated by lay counsellors with medication collection every 2-4 months; or (ii) referral to local primary healthcare clinics (PHC) with services provided by clinicians and medication collection every 1-2 months (local standard of care for postpartum ART). For evaluation, women were followed through 6-months postpartum with VL testing separate from either ART service. Through September 2015, n  = 129 women were enrolled (median age, 28 years; median time postpartum, 10 days). Overall, 65% ( n  = 84) chose adherence clubs and 35% ( n  = 45) chose PHCs; there were no demographic or clinical predictors of this choice. Location of service delivery was commonly cited as a reason for choice by women selecting either model of care; shorter waiting times, ability to receive ART from lay counsellors and less frequent appointments were motivations for choosing adherence clubs. Among women choosing adherence clubs, 15% never attended the service and another 11% attended the service but were not retained through six months postpartum. Overall, 86% of women ( n  = 111) remained in the evaluation through 6 months postpartum; in this group, there were no differences in VL<1000 copies/mL at six months postpartum between women choosing PHCs (88%) vs. adherence clubs (92%; p  = 0.483), but women who were not retained in adherence clubs were more likely to have VL≥1000 copies/mL compared to those who remained ( p  = 0.002). Adherence clubs may be a valuable model for postpartum women initiating ART in pregnancy, with good short-term outcomes observed during this critical period. To support optimal implementation, further research is needed into patient preferences for models of care, with consideration of integration of maternal and child health services, while ART adherence and retention require ongoing consideration in this population.

Adherence to Polyethylene Glycol Treatment in Children with Functional Constipation Is Associated with Parental Illness Perceptions, Satisfaction with Treatment, and Perceived Treatment Convenience.

PubMed

Koppen, Ilan Jasper Nader; van Wassenaer, Elsa A; Barendsen, Rinse W; Brand, Paul L; Benninga, Marc A

2018-05-10

To assess treatment adherence in children with functional constipation and to evaluate the association with parental beliefs about medication, illness perceptions, treatment satisfaction, and satisfaction with information about medication. A cross-sectional survey was administered among parents of children with functional constipation treated with polyethylene glycol. Adherence was measured via the Medication Adherence Report Scale (MARS-5, score 5-25), with greater scores indicating better adherence (scores ≥23 were defined as adherent). Beliefs about medication, illness perceptions, satisfaction with treatment, and satisfaction with information about treatment were measured with the Beliefs about Medication Questionnaire, the Brief Illness Perception Questionnaire, the Treatment Satisfaction Questionnaire for Medication (TSQM), and the Satisfaction with Information about Medication Questionnaire. Associations between the questionnaire scores and adherence (MARS-5 score as a continuous variable) were analyzed with regression analyses. In total, 43 of 115 included children (37%) were adherent (MARS-5 ≥23). Spearman rank correlation test revealed a statistically significant correlation between TSQM-convenience, TSQM-satisfaction, Brief Illness Perception Questionnaire question 8 (emotions), and the MARS-5 score (r s 0.342, P = .000; r s 0.258, P = .006; r s -0.192, P = .044), which suggests that parental perceived treatment convenience, satisfaction with treatment, and illness perceptions may affect adherence in children with functional constipation. In the hierarchical multivariate regression model, 22% of the variability of the MARS-5 score could be explained by the selected predictors. The TSQM-convenience score contributed the most to the model (β: 0.384, P = .000). Parents reported low adherence rates in their children with functional constipation. Treatment inconvenience, dissatisfaction with treatment, and the emotional impact of functional constipation may negatively influence treatment adherence. Copyright © 2018 Elsevier Inc. All rights reserved.

Role of Counseling to Promote Adherence in Healthy Lifestyle Medicine: Strategies to Improve Exercise Adherence and Enhance Physical Activity.

PubMed

Stonerock, Gregory L; Blumenthal, James A

Although healthy lifestyles (HL) offer a number of health benefits, nonadherence to recommended lifestyle changes remains a frequent and difficult obstacle to realizing these benefits. Behavioral counseling can improve adherence to an HL. However, individuals' motivation for change and resistance to altering unhealthy habits must be considered when developing an effective approach to counseling. In the present article, we review psychological, behavioral, and environmental factors that may promote adherence and contribute to nonadherence. We discuss two established models for counseling, motivational interviewing and the transtheoretical model of behavior change, and provide an example of how these approaches can be used to counsel patients to exercise and increase their levels of physical activity. Copyright © 2016 Elsevier Inc. All rights reserved.

Medical and psychosocial associates of nonadherence in adolescents with cancer.

PubMed

Hullmann, Stephanie E; Brumley, Lauren D; Schwartz, Lisa A

2015-01-01

The current study examined adherence to medication regimens among adolescents with cancer by applying the Pediatric Self-Management Model. Adolescents and their parents reported on adherence to medication, reasons for nonadherence, and patient-, family-, and community-level psychosocial variables. Adolescent- and parent-reported adherence were significantly correlated, with about half of the sample reporting perfect adherence. The majority reported "just forgot" as the most common reason for missed medication. Patient-, family-, and community-level variables were examined as predictors of adherence. With regard to individual factors, adolescents who endorsed perfect adherence reported a greater proportion of future-orientated goals and spent fewer days in outpatient clinic visits. For family factors, adolescents who endorsed perfect adherence reported greater social support from their family and were more likely to have a second caregiver who they perceived as overprotective. The community-level variable (social support from friends) tested did not emerge as a predictor of adherence. The results of this study provide direction for intervention efforts to target adolescent goals and family support in order to increase adolescent adherence to cancer treatment regimens. © 2014 by Association of Pediatric Hematology/Oncology Nurses.

Medical and Psychosocial Associates of Nonadherence in Adolescents With Cancer

PubMed Central

Hullmann, Stephanie E.; Brumley, Lauren D.; Schwartz, Lisa A.

2015-01-01

The current study examined adherence to medication regimens among adolescents with cancer by applying the Pediatric Self-Management Model. Adolescents and their parents reported on adherence to medication, reasons for nonadherence, and patient-, family-, and community-level psychosocial variables. Adolescent- and parent-reported adherence were significantly correlated, with about half of the sample reporting perfect adherence. The majority reported “just forgot” as the most common reason for missed medication. Patient-, family-, and community-level variables were examined as predictors of adherence. With regard to individual factors, adolescents who endorsed perfect adherence reported a greater proportion of future-orientated goals and spent fewer days in outpatient clinic visits. For family factors, adolescents who endorsed perfect adherence reported greater social support from their family and were more likely to have a second caregiver who they perceived as overprotective. The community-level variable (social support from friends) tested did not emerge as a predictor of adherence. The results of this study provide direction for intervention efforts to target adolescent goals and family support in order to increase adolescent adherence to cancer treatment regimens. PMID:25366574

The Role of Theory in Increasing Adherence to Prescribed Practice

PubMed Central

Richardson, Julie; Wishart, Laurie; Hanna, Steven

2009-01-01

ABSTRACT Purpose: The purpose of this article is to apply theoretical frameworks to adherence behaviour and to guide the development of an intervention to increase adherence to prescribed home programmes. Summary of Key Points: Delivering an effective intervention requires establishing one that is evidence based and of adequate dosage. Two-thirds of patients who receive home exercise prescriptions do not adhere to their home programme, which may contribute to their physiotherapy's being ineffective. The mediating concepts of self-efficacy (SE) and outcome expectations (OE) are common to the five relevant theories used to explain adherence to exercise: the health belief model, protection motivation theory, theory of reasoned action, theory of planned behaviour, and social cognitive theory. Conclusion/Recommendations: Few intervention studies with any theoretical underpinning have examined adherence to exercise. Even fewer have been designed to affect and measure change in the theoretical mediators of SE and OE in patient populations. Physiotherapists must consider increasing adherence as a component of effective physiotherapy. Ongoing research is needed to increase our understanding of adherence to prescribed home programmes and to design interventions to affect theoretical mediators for increasing adherence. PMID:20190989

Cognitive-behavioral therapy for persistent pain: does adherence after treatment affect outcome?

PubMed

Curran, Charlotte; Williams, Amanda C de C; Potts, Henry W W

2009-02-01

It is a tenet of cognitive behavioral treatment of persistent pain problems that ex-patients should adhere to treatment methods over the longer term, in order to maintain and to extend treatment gains. However, no research has quantified the causal influence of adherence on short-term outcome in this field. The aims of this study are to assess determinants of adherence to treatment recommendations in several domains, and to examine the extent to which cognitive and behavioral adherence predicts better outcome of cognitive behavioral treatment for persistent pain. Longitudinal data from a sample of 2345 persistent pain patients who attended a multicomponent treatment programme were subjected to structural equation modeling. Adherence emerged as a mediating factor linking post-treatment and follow-up treatment outcome, but contributed only 3% unique variance to follow-up outcomes. Combined end-of-treatment outcomes and adherence factors accounted for 72% of the variance in outcome at one-month follow-up. Notwithstanding shortcomings in the measurement of adherence, these findings question the emphasis normally given to adherence in the maintenance of behavioral and cognitive change, and clinical implications are discussed.

Illness and treatment perceptions are associated with adherence to medications, diet, and exercise in diabetic patients.

PubMed

Broadbent, Elizabeth; Donkin, Liesje; Stroh, Julia C

2011-02-01

To investigate diabetic patients' perceptions of illness and treatments, and explore relationships to adherence and blood glucose control. Forty-nine type 1 and one hundred and eight type 2 diabetic patients completed questionnaires assessing illness perceptions, treatment beliefs, and adherence to medications, diet, and exercise. Blood glucose control was assessed from blood tests. Patients rated medication more important than diet and exercise, and reported higher adherence to medications. Insulin was perceived as more helpful for diabetes, while antihypertensives and cholesterol medication were perceived more helpful for preventing heart problems. Perceptions were associated with adherence to insulin, cholesterol and antihypertensive medications, exercise, and diet. Blood glucose control in type 1 diabetic patients was associated with insulin adherence and perceived personal control, and in type 2 diabetic patients to being prescribed insulin or antihypertensives, and perceived personal control. Patients hold specific mental models about diabetes treatments, which are associated with adherence.

The Necessity-Concerns-Framework: A Multidimensional Theory Benefits from Multidimensional Analysis

PubMed Central

Phillips, L. Alison; Diefenbach, Michael; Kronish, Ian M.; Negron, Rennie M.; Horowitz, Carol R.

2014-01-01

Background Patients’ medication-related concerns and necessity-beliefs predict adherence. Evaluation of the potentially complex interplay of these two dimensions has been limited because of methods that reduce them to a single dimension (difference scores). Purpose We use polynomial regression to assess the multidimensional effect of stroke-event survivors’ medication-related concerns and necessity-beliefs on their adherence to stroke-prevention medication. Methods Survivors (n=600) rated their concerns, necessity-beliefs, and adherence to medication. Confirmatory and exploratory polynomial regression determined the best-fitting multidimensional model. Results As posited by the Necessity-Concerns Framework (NCF), the greatest and lowest adherence was reported by those with strong necessity-beliefs/weak concerns and strong concerns/weak necessity-beliefs, respectively. However, as could not be assessed using a difference-score model, patients with ambivalent beliefs were less adherent than those exhibiting indifference. Conclusions Polynomial regression allows for assessment of the multidimensional nature of the NCF. Clinicians/Researchers should be aware that concerns and necessity dimensions are not polar opposites. PMID:24500078

The necessity-concerns framework: a multidimensional theory benefits from multidimensional analysis.

PubMed

Phillips, L Alison; Diefenbach, Michael A; Kronish, Ian M; Negron, Rennie M; Horowitz, Carol R

2014-08-01

Patients' medication-related concerns and necessity-beliefs predict adherence. Evaluation of the potentially complex interplay of these two dimensions has been limited because of methods that reduce them to a single dimension (difference scores). We use polynomial regression to assess the multidimensional effect of stroke-event survivors' medication-related concerns and necessity beliefs on their adherence to stroke-prevention medication. Survivors (n = 600) rated their concerns, necessity beliefs, and adherence to medication. Confirmatory and exploratory polynomial regression determined the best-fitting multidimensional model. As posited by the necessity-concerns framework (NCF), the greatest and lowest adherence was reported by those necessity weak concerns and strong concerns/weak Necessity-Beliefs, respectively. However, as could not be assessed using a difference-score model, patients with ambivalent beliefs were less adherent than those exhibiting indifference. Polynomial regression allows for assessment of the multidimensional nature of the NCF. Clinicians/Researchers should be aware that concerns and necessity dimensions are not polar opposites.

Medicare long-term CPAP coverage policy: a cost-utility analysis.

PubMed

Billings, Martha E; Kapur, Vishesh K

2013-10-15

CPAP is an effective treatment for OSA that may reduce health care utilization and costs. Medicare currently reimburses the costs of long-term CPAP therapy only if the patient is adherent during a 90-day trial. If not, Medicare requires a repeat polysomnogram (PSG) and another trial which seems empirically not cost-effective. We modeled the cost-effectiveness of current Medicare policy compared to an alternative policy (clinic-only) without the adherence criterion and repeat PSG. Cost-utility and cost-effectiveness analysis. U.S. Medicare Population. N/A. N/A. We created a decision tree modeling (1) clinic only follow-up vs. (2) current Medicare policy. Costs were assigned based on Medicare reimbursement rates in 2012. Sensitivity analyses were conducted to test our assumptions. We estimated cumulative costs, overall adherence, and QALY gained for a 5-year time horizon from the perspective of Medicare as the payer. Current Medicare policy is more costly than the clinic-only policy but has higher net adherence and improved utility. Current Medicare policy compared to clinic-only policy costs $30,544 more per QALY. Current CMS policy promotes early identification of those more likely to adhere to CPAP therapy by requiring strict adherence standards. The policy effect is to deny coverage to those unlikely to use CPAP long-term and prevent wasted resources. Future studies are needed to measure long-term adherence in an elderly population with and without current adherence requirements to verify the cost-effectiveness of a policy change.

Can purchasing information be used to predict adherence to cardiovascular medications? An analysis of linked retail pharmacy and insurance claims data.

PubMed

Krumme, Alexis A; Sanfélix-Gimeno, Gabriel; Franklin, Jessica M; Isaman, Danielle L; Mahesri, Mufaddal; Matlin, Olga S; Shrank, William H; Brennan, Troyen A; Brill, Gregory; Choudhry, Niteesh K

2016-11-09

The use of retail purchasing data may improve adherence prediction over approaches using healthcare insurance claims alone. Retrospective. A cohort of patients who received prescription medication benefits through CVS Caremark, used a CVS Pharmacy ExtraCare Health Care (ECHC) loyalty card, and initiated a statin medication in 2011. We evaluated associations between retail purchasing patterns and optimal adherence to statins in the 12 subsequent months. Among 11 010 statin initiators, 43% were optimally adherent at 12 months of follow-up. Greater numbers of store visits per month and dollar amount per visit were positively associated with optimal adherence, as was making a purchase on the same day as filling a prescription (p<0.0001 for all). Models to predict adherence using retail purchase variables had low discriminative ability (C-statistic: 0.563), while models with both clinical and retail purchase variables achieved a C-statistic of 0.617. While the use of retail purchases may improve the discriminative ability of claims-based approaches, these data alone appear inadequate for adherence prediction, even with the addition of more complex analytical approaches. Nevertheless, associations between retail purchasing behaviours and adherence could inform the development of quality improvement interventions. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Perceived Social Standing, Medication Nonadherence, and Systolic Blood Pressure in the Rural South.

PubMed

Cummings, Doyle M; Wu, Jia-Rong; Cene, Crystal; Halladay, Jacquie; Donahue, Katrina E; Hinderliter, Alan; Miller, Cassandra; Garcia, Beverly; Penn, Dolly; Tillman, Jim; DeWalt, Darren

2016-01-01

Little is known about how perceived social standing versus traditional socioeconomic characteristics influence medication adherence and blood pressure (BP) among African American and white patients with hypertension in the rural southeastern United States. Perceived social standing, socioeconomic characteristics, self-reported antihypertensive medication adherence, and BP were measured at baseline in a cohort of rural African American and white patients (n = 495) with uncontrolled hypertension attending primary care practices. Multivariate models examined the relationship of perceived social standing and socioeconomic indicators with medication adherence and systolic BP. Medication nonadherence was reported by 40% of patients. Younger age [β = 0.20; P = .001], African American race [β = -0.30; P = .03], and lower perceived social standing [β = 0.08; P = .002] but not sex or traditional socioeconomic characteristics including education and household income, were significantly associated with lower medication adherence. Race-specific analyses revealed that this pattern was limited to African Americans and not observed in whites. In stepwise modeling, older age [β = 0.57, P = .001], African American race [β = 4.4; P = .03], and lower medication adherence [β = -1.7, P = .01] but not gender, education, or household income, were significantly associated with higher systolic BP. Lower perceived social standing and age, but not traditional socioeconomic characteristics, were significantly associated with lower medication adherence in African Americans. Lower medication adherence was associated with higher systolic BP. These findings suggest the need for tailored, culturally relevant medication adherence interventions in rural communities. © 2015 National Rural Health Association.

The bias against new innovations in health care: value uncertainty and willingness to pay.

PubMed

Walton, Surrey M; Graves, Philip E; Mueser, Peter R; Dow, Jay K

2002-01-01

This paper offers a model for the bias found in willingness-to-pay valuations against new treatments. For example, this bias provides an explanation for patient preferences that make it difficult for formularies to take treatments off their lists, even when newer treatments would appear to be clearly preferable. The appeal of the model, which is based on imperfect information, is that it is consistent with rational preferences and rational behavior by patients, which are necessary for standard models and methods related to decision theory, cost-effectiveness, and efficiency.

Recommendations on Model Fidelity for Wind Turbine Gearbox Simulations; NREL (National Renewable Energy Laboratory)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Keller, J.; Lacava, W.; Austin, J.

2015-02-01

This work investigates the minimum level of fidelity required to accurately simulate wind turbine gearboxes using state-of-the-art design tools. Excessive model fidelity including drivetrain complexity, gearbox complexity, excitation sources, and imperfections, significantly increases computational time, but may not provide a commensurate increase in the value of the results. Essential designparameters are evaluated, including the planetary load-sharing factor, gear tooth load distribution, and sun orbit motion. Based on the sensitivity study results, recommendations for the minimum model fidelities are provided.

Fusion of Imperfect Information in the Unified Framework of Random Sets Theory: Application to Target Identification

DTIC Science & Technology

2007-11-01

Florea, Anne-Laure Jousselme, Éloi Bossé ; DRDC Valcartier TR 2003-319 ; R & D pour la défense Canada – Valcartier ; novembre 2007. Contexte : Pour...12 3.3.2 Imprecise information . . . . . . . . . . . . . . . . . . . . . 13 3.3.3 Uncertain and imprecise information...information proposed by Philippe Smets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Figure 5: The process of information modelling

CONSTRUCTING A FLEXIBLE LIKELIHOOD FUNCTION FOR SPECTROSCOPIC INFERENCE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Czekala, Ian; Andrews, Sean M.; Mandel, Kaisey S.

2015-10-20

We present a modular, extensible likelihood framework for spectroscopic inference based on synthetic model spectra. The subtraction of an imperfect model from a continuously sampled spectrum introduces covariance between adjacent datapoints (pixels) into the residual spectrum. For the high signal-to-noise data with large spectral range that is commonly employed in stellar astrophysics, that covariant structure can lead to dramatically underestimated parameter uncertainties (and, in some cases, biases). We construct a likelihood function that accounts for the structure of the covariance matrix, utilizing the machinery of Gaussian process kernels. This framework specifically addresses the common problem of mismatches in model spectralmore » line strengths (with respect to data) due to intrinsic model imperfections (e.g., in the atomic/molecular databases or opacity prescriptions) by developing a novel local covariance kernel formalism that identifies and self-consistently downweights pathological spectral line “outliers.” By fitting many spectra in a hierarchical manner, these local kernels provide a mechanism to learn about and build data-driven corrections to synthetic spectral libraries. An open-source software implementation of this approach is available at http://iancze.github.io/Starfish, including a sophisticated probabilistic scheme for spectral interpolation when using model libraries that are sparsely sampled in the stellar parameters. We demonstrate some salient features of the framework by fitting the high-resolution V-band spectrum of WASP-14, an F5 dwarf with a transiting exoplanet, and the moderate-resolution K-band spectrum of Gliese 51, an M5 field dwarf.« less

Mixed Effects Models for Resampled Network Statistics Improves Statistical Power to Find Differences in Multi-Subject Functional Connectivity

PubMed Central

Narayan, Manjari; Allen, Genevera I.

2016-01-01

Many complex brain disorders, such as autism spectrum disorders, exhibit a wide range of symptoms and disability. To understand how brain communication is impaired in such conditions, functional connectivity studies seek to understand individual differences in brain network structure in terms of covariates that measure symptom severity. In practice, however, functional connectivity is not observed but estimated from complex and noisy neural activity measurements. Imperfect subject network estimates can compromise subsequent efforts to detect covariate effects on network structure. We address this problem in the case of Gaussian graphical models of functional connectivity, by proposing novel two-level models that treat both subject level networks and population level covariate effects as unknown parameters. To account for imperfectly estimated subject level networks when fitting these models, we propose two related approaches—R2 based on resampling and random effects test statistics, and R3 that additionally employs random adaptive penalization. Simulation studies using realistic graph structures reveal that R2 and R3 have superior statistical power to detect covariate effects compared to existing approaches, particularly when the number of within subject observations is comparable to the size of subject networks. Using our novel models and methods to study parts of the ABIDE dataset, we find evidence of hypoconnectivity associated with symptom severity in autism spectrum disorders, in frontoparietal and limbic systems as well as in anterior and posterior cingulate cortices. PMID:27147940

Assessment of the effects of azimuthal mode number perturbations upon the implosion processes of fluids in cylinders

NASA Astrophysics Data System (ADS)

Lindstrom, Michael

2017-06-01

Fluid instabilities arise in a variety of contexts and are often unwanted results of engineering imperfections. In one particular model for a magnetized target fusion reactor, a pressure wave is propagated in a cylindrical annulus comprised of a dense fluid before impinging upon a plasma and imploding it. Part of the success of the apparatus is a function of how axially-symmetric the final pressure pulse is upon impacting the plasma. We study a simple model for the implosion of the system to study how imperfections in the pressure imparted on the outer circumference grow due to geometric focusing. Our methodology entails linearizing the compressible Euler equations for mass and momentum conservation about a cylindrically symmetric problem and analysing the perturbed profiles at different mode numbers. The linearized system gives rise to singular shocks and through analysing the perturbation profiles at various times, we infer that high mode numbers are dampened through the propagation. We also study the Linear Klein-Gordon equation in the context of stability of linear cylindrical wave formation whereby highly oscillatory, bounded behaviour is observed in a far field solution.

Estimation of occupancy, breeding success, and predicted abundance of golden eagles (Aquila chrysaetos) in the Diablo Range, California, 2014

USGS Publications Warehouse

Wiens, J. David; Kolar, Patrick S.; Fuller, Mark R.; Hunt, W. Grainger; Hunt, Teresa

2015-01-01

We used a multistate occupancy sampling design to estimate occupancy, breeding success, and abundance of territorial pairs of golden eagles (Aquila chrysaetos) in the Diablo Range, California, in 2014. This method uses the spatial pattern of detections and non-detections over repeated visits to survey sites to estimate probabilities of occupancy and successful reproduction while accounting for imperfect detection of golden eagles and their young during surveys. The estimated probability of detecting territorial pairs of golden eagles and their young was less than 1 and varied with time of the breeding season, as did the probability of correctly classifying a pair’s breeding status. Imperfect detection and breeding classification led to a sizeable difference between the uncorrected, naïve estimate of the proportion of occupied sites where successful reproduction was observed (0.20) and the model-based estimate (0.30). The analysis further indicated a relatively high overall probability of landscape occupancy by pairs of golden eagles (0.67, standard error = 0.06), but that areas with the greatest occupancy and reproductive potential were patchily distributed. We documented a total of 138 territorial pairs of golden eagles during surveys completed in the 2014 breeding season, which represented about one-half of the 280 pairs we estimated to occur in the broader 5,169-square kilometer region sampled. The study results emphasize the importance of accounting for imperfect detection and spatial heterogeneity in studies of site occupancy, breeding success, and abundance of golden eagles.

A general panel sizing computer code and its application to composite structural panels

NASA Technical Reports Server (NTRS)

Anderson, M. S.; Stroud, W. J.

1978-01-01

A computer code for obtaining the dimensions of optimum (least mass) stiffened composite structural panels is described. The procedure, which is based on nonlinear mathematical programming and a rigorous buckling analysis, is applicable to general cross sections under general loading conditions causing buckling. A simplified method of accounting for bow-type imperfections is also included. Design studies in the form of structural efficiency charts for axial compression loading are made with the code for blade and hat stiffened panels. The effects on panel mass of imperfections, material strength limitations, and panel stiffness requirements are also examined. Comparisons with previously published experimental data show that accounting for imperfections improves correlation between theory and experiment.

Detecting Edges in Images by Use of Fuzzy Reasoning

NASA Technical Reports Server (NTRS)

Dominguez, Jesus A.; Klinko, Steve

2003-01-01

A method of processing digital image data to detect edges includes the use of fuzzy reasoning. The method is completely adaptive and does not require any advance knowledge of an image. During initial processing of image data at a low level of abstraction, the nature of the data is indeterminate. Fuzzy reasoning is used in the present method because it affords an ability to construct useful abstractions from approximate, incomplete, and otherwise imperfect sets of data. Humans are able to make some sense of even unfamiliar objects that have imperfect high-level representations. It appears that to perceive unfamiliar objects or to perceive familiar objects in imperfect images, humans apply heuristic algorithms to understand the images

Equilibrium paths of an imperfect plate with respect to its aspect ratio

NASA Astrophysics Data System (ADS)

Psotny, Martin

2017-07-01

The stability analysis of a rectangular plate loaded in compression is presented, a specialized code based on FEM has been created. Special finite element with 48 degrees of freedom has been used for analysis. The nonlinear finite element method equations are derived from the variational principle of minimum of total potential energy. To trace the complete nonlinear equilibrium paths, the Newton-Raphson iteration algorithm is used, load versus displacement control was changed during the calculation process. The peculiarities of the effects of the initial imperfections on the load-deflection paths are investigated with respect to aspect ratio of the plate. Special attention is paid to the influence of imperfections on the post-critical buckling mode.

Deterministic Bragg Coherent Diffraction Imaging.

PubMed

Pavlov, Konstantin M; Punegov, Vasily I; Morgan, Kaye S; Schmalz, Gerd; Paganin, David M

2017-04-25

A deterministic variant of Bragg Coherent Diffraction Imaging is introduced in its kinematical approximation, for X-ray scattering from an imperfect crystal whose imperfections span no more than half of the volume of the crystal. This approach provides a unique analytical reconstruction of the object's structure factor and displacement fields from the 3D diffracted intensity distribution centred around any particular reciprocal lattice vector. The simple closed-form reconstruction algorithm, which requires only one multiplication and one Fourier transformation, is not restricted by assumptions of smallness of the displacement field. The algorithm performs well in simulations incorporating a variety of conditions, including both realistic levels of noise and departures from ideality in the reference (i.e. imperfection-free) part of the crystal.

Type D Personality, Self-Efficacy, and Medication Adherence in Patients with Heart Failure

PubMed Central

Wu, Jia-Rong; Song, Eun Kyeung; Moser, Debra K.

2015-01-01

Background Type D personality is a known predictor of non-adherence to prescribed medication regimens among patients with heart failure (HF). Both Type D personality and non-adherence are independent predictors of poor health outcomes among HF patients. Self-efficacy, which is modifiable, is also associated with medication adherence. Objectives To determine the relationships among Type D personality, medication self-efficacy, and medication adherence in 84 patients with HF. Methods Medication self-efficacy, Type D personality, medication adherence, demographic and clinical data were collected. Hierarchical linear regression and mediation analyses were used. Results Type D patients were more likely to have lower medication self-efficacy (p = .023) and poorer medication adherence (p = .027) compared with non-Type D patients. Low medication self-efficacy was associated with poor medication adherence (p < .001). Type D did not predict (p = .422) medication adherence after entering medication self-efficacy in the model demonstrating that medication self-efficacy was a mediator of the relationship between Type D and medication adherence. Conclusions Medication self-efficacy mediates the relationship between Type D personality and medication adherence. Developing and applying interventions to enhance medication self-efficacy for Type D patients may help to sever the link between Type D personality and poor outcomes. PMID:25979573

Adherent Raindrop Modeling, Detectionand Removal in Video.

PubMed

You, Shaodi; Tan, Robby T; Kawakami, Rei; Mukaigawa, Yasuhiro; Ikeuchi, Katsushi

2016-09-01

Raindrops adhered to a windscreen or window glass can significantly degrade the visibility of a scene. Modeling, detecting and removing raindrops will, therefore, benefit many computer vision applications, particularly outdoor surveillance systems and intelligent vehicle systems. In this paper, a method that automatically detects and removes adherent raindrops is introduced. The core idea is to exploit the local spatio-temporal derivatives of raindrops. To accomplish the idea, we first model adherent raindrops using law of physics, and detect raindrops based on these models in combination with motion and intensity temporal derivatives of the input video. Having detected the raindrops, we remove them and restore the images based on an analysis that some areas of raindrops completely occludes the scene, and some other areas occlude only partially. For partially occluding areas, we restore them by retrieving as much as possible information of the scene, namely, by solving a blending function on the detected partially occluding areas using the temporal intensity derivative. For completely occluding areas, we recover them by using a video completion technique. Experimental results using various real videos show the effectiveness of our method.

Applying the Resources and Supports in Self-Management Framework to Examine Ophthalmologist-Patient Communication and Glaucoma Medication Adherence

ERIC Educational Resources Information Center

Sleath, B.; Carpenter, D. M.; Blalock, S. J.; Sayner, R.; Muir, K. W.; Slota, C.; Giangiacomo, A. L.; Hartnett, M. E.; Tudor, G.; Robin, A. L.

2015-01-01

Little is known about how ophthalmologist-patient communication over time is associated with glaucoma patient long-term adherence. The purpose of our study was to examine the association between provider use of components of the resources and supports in self-management model when communicating with patients and adherence to glaucoma medications…

Impact of Appointment-Based Medication Synchronization on Proportion of Days Covered for Chronic Medications.

PubMed

Dao, Nancy; Lee, Sun; Hata, Micah; Sarino, Lord

2018-05-22

Appointment-based medication synchronization (ABMS) programs have been associated with increased adherence and persistence to chronic medications. Adherence to statin therapy, angiotensin-converting enzyme inhibitors (ACEIs), angiotensin receptor blockers (ARBs), and non-insulin antidiabetic medications (NIDM) are used to determine a health plan's Centers for Medicare and Medicaid Services (CMS) Star Rating under a pay-for-performance model. The objective of this study was to evaluate the impact of implementing an ABMS program on overall pharmacy adherence measures for statins, ACEI/ARBs, and NIDM, as presented through the Electronic Quality Improvement Platform for Plans and Pharmacies (EQuIPP©) platform. This retrospective, pre-post ABMS program study evaluated EQuIPP© generated adherence performance measures, represented as proportion of days covered (PDC), 6-months before and 6- and 12-months after the ABMS service for statin therapy, ACEIs/ARBs, and NIDM. All adherence measures showed statistically significant improvement in PDC percentage post ABMS implementation, except for NIDM percentage in 6-months post-ABMS service. This study shows that a comprehensive medication synchronization program can enhance adherence measures that are important to health plans to increase CMS Star Rating under a pay-for-performance model.

Partitioning Detectability Components in Populations Subject to Within-Season Temporary Emigration Using Binomial Mixture Models

PubMed Central

O’Donnell, Katherine M.; Thompson, Frank R.; Semlitsch, Raymond D.

2015-01-01

Detectability of individual animals is highly variable and nearly always < 1; imperfect detection must be accounted for to reliably estimate population sizes and trends. Hierarchical models can simultaneously estimate abundance and effective detection probability, but there are several different mechanisms that cause variation in detectability. Neglecting temporary emigration can lead to biased population estimates because availability and conditional detection probability are confounded. In this study, we extend previous hierarchical binomial mixture models to account for multiple sources of variation in detectability. The state process of the hierarchical model describes ecological mechanisms that generate spatial and temporal patterns in abundance, while the observation model accounts for the imperfect nature of counting individuals due to temporary emigration and false absences. We illustrate our model’s potential advantages, including the allowance of temporary emigration between sampling periods, with a case study of southern red-backed salamanders Plethodon serratus. We fit our model and a standard binomial mixture model to counts of terrestrial salamanders surveyed at 40 sites during 3–5 surveys each spring and fall 2010–2012. Our models generated similar parameter estimates to standard binomial mixture models. Aspect was the best predictor of salamander abundance in our case study; abundance increased as aspect became more northeasterly. Increased time-since-rainfall strongly decreased salamander surface activity (i.e. availability for sampling), while higher amounts of woody cover objects and rocks increased conditional detection probability (i.e. probability of capture, given an animal is exposed to sampling). By explicitly accounting for both components of detectability, we increased congruence between our statistical modeling and our ecological understanding of the system. We stress the importance of choosing survey locations and protocols that maximize species availability and conditional detection probability to increase population parameter estimate reliability. PMID:25775182

Association of cinacalcet adherence and costs in patients on dialysis.

PubMed

Lee, Andrew; Song, Xue; Khan, Irfan; Belozeroff, Vasily; Goodman, William; Fulcher, Nicole; Diakun, David

2011-01-01

In addition to negative impacts on clinical effectiveness in treating secondary hyperparathyroidism, low adherence to cinacalcet may have negative impacts on healthcare costs. This study assessed the relationship between medication adherence and healthcare costs among US patients on dialysis given cinacalcet to manage secondary hyperparathyroidism. Retrospective cohort study of patients who were receiving dialysis with an initial cinacalcet prescription between January 2004 and April 2010 and who survived ≥12 months. Longitudinal, integrated medical, and pharmacy claims data from the MarketScan? database were used to calculate medication possession ratios (MPR) over 12 months and to examine the association of adherence with inpatient, outpatient, emergency room, outpatient medication, and total costs while controlling for patient characteristics, co-morbid medical conditions, and concomitant medication MPR in a multivariate regression model. Patients were dichotomized as adherent (<180 days refill gap) or non-adherent (≥180 day refill gap). Adherent patients were further dichotomized as low adherent (<0.8 MPR) and high adherent (≥0.8 MPR). The final study cohort included 4923 patients. After 12 months, 46% were non-adherent, 27% were low adherent, and 28% were high adherent. Greater cinacalcet adherence was associated with significantly lower inpatient costs with cost-savings of a greater magnitude than the increased medication costs. This study demonstrated that low adherence to cinacalcet, which may be associated with undesirable clinical and health-economic outcomes, is common. Despite limitations inherent in retrospective studies of claims databases, such as unobserved confounding, non-discrimination between prescription fill and actual use, and not knowing the reasons for non-adherence, these results suggest that inpatient cost savings of $8899, more than offset higher medication costs of $5858 associated with increased cinacalcet adherence.

Medical makeup: the correction of hyperpigmentation disorders.

PubMed

Nonni, J

2012-12-01

Medical makeup corrects skin tone imperfections with dermocosmetic products, which bring together tolerance efficacy, colour neutralization and sun protection. Highly suitable for imperfections caused by hyperpigmentation, it allows patients affected by these disorders to cover them up effectively and discretely, giving them a better quality of life. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

On Crosslinguistic Variations in Imperfective Aspect: The Case of L2 Korean

ERIC Educational Resources Information Center

Lee, EunHee; Kim, Hae-Young

2007-01-01

This article examines the acquisition of Korean imperfective markers, the progressive "-ko iss-" and the resultative "-a iss-," with a view to understanding how tense/aspect morphology expands beyond prototype associations with inherent aspects of the verbs. We hypothesized that "-a iss-" will develop later than "-ko iss-," but that the…

Solar-cell defect analyzer

NASA Technical Reports Server (NTRS)

Gauthier, M. K.; Miller, E. L.; Shumka, A.

1980-01-01

Laser-Scanning System pinpoints imperfections in solar cells. Entire solar panels containing large numbers of cells can be scanned. Although technique is similar to use of scanning electron microscope (SEM) to locate microscopic imperfections, it differs in that large areas may be examined, including entire solar panels, and it is not necessary to remove cover glass or encapsulants.

Modular Spectral Inference Framework Applied to Young Stars and Brown Dwarfs

NASA Technical Reports Server (NTRS)

Gully-Santiago, Michael A.; Marley, Mark S.

2017-01-01

In practice, synthetic spectral models are imperfect, causing inaccurate estimates of stellar parameters. Using forward modeling and statistical inference, we derive accurate stellar parameters for a given observed spectrum by emulating a grid of precomputed spectra to track uncertainties. Spectral inference as applied to brown dwarfs re: Synthetic spectral models (Marley et al 1996 and 2014) via the newest grid spans a massive multi-dimensional grid applied to IGRINS spectra, improving atmospheric models for JWST. When applied to young stars(10Myr) with large starpots, they can be measured spectroscopically, especially in the near-IR with IGRINS.

Multi-pair two-way massive MIMO AF relaying with ZFR/ZFT beamforming and imperfect CSI over ricean fading channels

NASA Astrophysics Data System (ADS)

Xu, Kui; Sun, Xiaoli; Zhang, Dongmei

2016-10-01

This paper investigates the spectral and energy efficiencies of a multi-pair two-way amplify-and-forward (AF) relay system over Ricean fading channels, where multiple user-pairs exchange information within pair through a relay with very large number of antennas, while each user equipped with a single antenna. Firstly, beamforming matrixe of zero-forcing reception/zero-forcing transmission (ZFR/ZFT) with imperfect channel state information (CSI) at the relay is given. Then, the unified asymptotic signal-to-interference-plus-noise ratio (SINR) expressions with imperfect CSI are obtained analytically. Finally, two power scaling schemes are proposed and the asymptotic spectral and energy efficiencies based on the proposed power scaling schemes are derived and verified by the Monte-Carlo simulations. Theoretical analyses and simulation results show that with imperfect CSI, if the number of relay antennas grows asymptotically large, we need cut down the transmit power of each user and relay to different proportion when the Ricean K-factor is non-zero and zero (Rayleigh fading) in order to maintain a desirable rate.

[Poisoning by exhaust gas of the imperfect combustion of natural gas: 22 cases study].

PubMed

Dong, Li-Min; Zhao, Hai; Zhang, Ming-Chang; He, Meng

2014-10-01

To analyze the case characteristics of poisoning by exhaust gas of the imperfect combustion of natural gas and provide references for forensic identification and prevention of such accidents. Twenty-two cases of poisoning by exhaust gas of the imperfect combustion of natural gas in Minhang District during 2004 to 2013 were collected. Some aspects such as general conditions of deaths, incidence time, weather, field investigation, and autopsy were retrospectively analyzed. In the 22 cases, there were 15 males and 16 females. The age range was between 2 and 82 years old. The major occurring time was in January or February (8 cases in each) and the cases almost occurred in small area room (21 cases). There was wide crack next to the exhaust port when the gas water heater was been used in all cases. There are more prone to occurrence of exhaust gas poisoning of imperfect combustion of natural gas in small area room with a ventilation window near the exhaust port of gas water heated. It shows that the scene of combustion exhaust gas poisoning should be more concerned in the cold season.

Attenuation of thermal neutrons by an imperfect single crystal

NASA Astrophysics Data System (ADS)

Naguib, K.; Adib, M.

1996-06-01

A semi-empirical formula is given which allows one to calculate the total thermal cross section of an imperfect single crystal as a function of crystal constants, temperature and neutron energy E, in the energy range between 3 meV and 10 eV. The formula also includes the contribution of the parasitic Bragg scattering to the total cross section that takes into account the crystal mosaic spread value and its orientation with respect to the neutron beam direction. A computer program (ISCANF) was developed to calculate the total attenuation of neutrons using the proposed formula. The ISCANF program was applied to investigate the neutron attenuation through a copper single crystal. The calculated values of the neutron transmission through the imperfect copper single crystal were fitted to the measured ones in the energy range 3 - 40 meV at different crystal orientations. The result of fitting shows that use of the computer program ISCANF allows one to predict the behaviour of the total cross section of an imperfect copper single crystal for the whole energy range.

A novel co-culture model of murine K12 osteosarcoma cells and S. aureus on common orthopedic implant materials: 'the race to the surface' studied in vitro.

PubMed

McConda, David B; Karnes, Jonathan M; Hamza, Therwa; Lindsey, Brock A

2016-07-01

Infection is a major cause of orthopedic implant failure. There are few studies assessing both tissue cell and bacterial adherence on common orthopedic implant materials in a co-culture environment. An in vitro co-culture model was created using K12 osteosarcoma cells and Staphylococcus aureus in a medium incubated over metal disks for 48 h. The results showed that, in the presence of S. aureus, there were fewer osteosarcoma cells attached to the disks for all substrata tested. There were significantly more osteosarcoma cells adhering to the cobalt chrome than the stainless steel and titanium disks. Overall, in the presence of osteosarcoma cells, there were more bacteria adhering to the disks for all the substrata tested, with significantly more bacteria adhering to the stainless steel disks compared to cobalt chrome and titanium disks. Scanning electron microscopy verified that osteosarcoma cells and bacteria were adherent to the metal disks after incubation for 48 h. Furthermore, the observation that more bacteria were in the co-culture than in the control sample suggests that the osteosarcoma cells serve as a nutrient source for the bacteria. Future models assessing the interaction of osteogenic cells with bacteria on a substratum would be improved if the model accounted for the role of the immune system in secondary bone healing.

Elements of the Veterans Health Administration Patient-Centered Medical Home are Associated with Greater Adherence to Oral Hypoglycemic Agents in Patients with Diabetes.

PubMed

Meo, Nicholas; Wong, Edwin; Sun, Haili; Curtis, Idamay; Batten, Adam; Fihn, Stephan D; Nelson, Karin

2018-04-01

In 2010, Veterans Health Administration (VHA) primary care clinics adopted a patient-centered medical home (PCMH) model. This study sought to examine the association between the organizational features related to adoption of PCMH and the level of adherence to oral hypoglycemic agents (OHAs) among patients with diabetes. This retrospective cohort study involved 757 VA clinics that provide primary care to 440,971 patients with diabetes who were taking OHAs in fiscal year 2012. One-year refill-based medication possession ratios (MPRs) were calculated at the patient level. Clinic-level adherence was defined as the proportion of clinics with MPR ≥80%. Risk adjustment of adherence was performed using logistic regression to account for differences in patient populations at clinics. Eight domains of the PCMH model (ie, access, continuity, coordination, teamwork, comprehensive care, self-management, communication, shared decision making) were assessed using items from a previously validated index. Multivariate linear regression was applied to identify PCMH components associated with clinic-level adherence. Patients with diabetes per clinic ranged from 100 to 5011. The average level of adherence to OHAs among clinics ranged from 52.8% to 61.9% (interquartile range = 57.9% to 59.4%). In multivariate analysis, organizational features associated with higher clinic-level adherence included access to routine care (standardized beta [Sβ] = .21, P = .004), having a respectful office staff (Sβ = 0.21, P = .002), and utilization of telephone encounters (Sβ = 0.23, P < .001). Among a national cohort of veterans with diabetes, overall PCMH implementation did not significantly increase adherence to oral hypoglycemic agents, although aspects of implementation were associated with increased adherence. Measures of access to care appear the most significant.

Occupancy models to study wildlife

USGS Publications Warehouse

Bailey, Larissa; Adams, Michael John

2005-01-01

Many wildlife studies seek to understand changes or differences in the proportion of sites occupied by a species of interest. These studies are hampered by imperfect detection of these species, which can result in some sites appearing to be unoccupied that are actually occupied. Occupancy models solve this problem and produce unbiased estimates of occupancy and related parameters. Required data (detection/non-detection information) are relatively simple and inexpensive to collect. Software is available free of charge to aid investigators in occupancy estimation.

Sensitivity Study for Long Term Reliability

NASA Technical Reports Server (NTRS)

White, Allan L.

2008-01-01

This paper illustrates using Markov models to establish system and maintenance requirements for small electronic controllers where the goal is a high probability of continuous service for a long period of time. The system and maintenance items considered are quality of components, various degrees of simple redundancy, redundancy with reconfiguration, diagnostic levels, periodic maintenance, and preventive maintenance. Markov models permit a quantitative investigation with comparison and contrast. An element of special interest is the use of conditional probability to study the combination of imperfect diagnostics and periodic maintenance.

Progressive Failure Studies of Composite Panels with and without Cutouts

NASA Technical Reports Server (NTRS)

Jaunky, Navin; Ambur, Damodar R.; Davila, Carlos G.; Hilburger, Mark; Bushnell, Dennis M. (Technical Monitor)

2001-01-01

Progressive failure analyses results are presented for composite panels with and without a cutout and subjected to in-plane shear loading and compression loading well into their postbuckling regime. Ply damage modes such as matrix cracking, fiber-matrix shear, and fiber failure are modeled by degrading the material properties. Results from finite element analyses are compared with experimental data. Good agreement between experimental data and numerical results are observed for most structural configurations when initial geometric imperfections are appropriately modeled.

Progressive Failure Studies of Composite Panels With and Without Cutouts

NASA Technical Reports Server (NTRS)

Ambur, Damodar R.; Jaunky, Navin; Davila, Carlos G.; Hilburger, Mark

2001-01-01

Progressive failure analyses results are presented for composite panels with and without a cutout and are subjected to in-plane shear loading and compression loading well into their post-buckling regime. Ply damage modes such as matrix cracking, fiber-matrix shear, and fiber failure are modeled by degrading the material properties. Results from finite element analyses are compared with experimental data. Good agreement between experimental data and numerical results are observed for most structural configurations when initial geometric imperfections are appropriately modeled.

The mechanics of gyroscope ball bearings

NASA Astrophysics Data System (ADS)

Zhuravlev, V. F.; Balmont, V. B.

Various aspects of the mechanics of gyroscopes are examined with emphasis on the elastic properties of the radial thrust ball bearings of the main axle and of the radial ball bearings of the gimbal suspension, covers, and flanges. Particular attention is given to the statics, kinematics, and dynamics of imperfect bearings. A stiffnes model convenient for engineering calculations is developed. A gyroscope vibration theory is proposed, and methods for reducing and preventing vibration are analyzed. The validity of the models proposed here is supported by experimental data.

Low Pretreatment Impulsivity and High Medication Adherence Increase the Odds of Abstinence in a Trial of N-Acetylcysteine in Adolescents with Cannabis Use Disorder

PubMed Central

Bentzley, Jessica P.; Tomko, Rachel L.; Gray, Kevin M.

2016-01-01

Background In light of recent progress toward pharmacologic interventions to treat adolescent cannabis use disorder, it is important to consider which adolescent characteristics may be associated with a favorable response to treatment. This study presents secondary analyses from a parent randomized controlled trial of N-acetylcysteine (NAC) in adolescents with cannabis use disorder. We hypothesized high pretreatment impulsivity and medication non-adherence would be associated with reduced abstinence rates. Methods Participants were treatment-seeking adolescents (N = 115) who met criteria for cannabis use disorder and were assessed for pretreatment impulsivity. They received 1200 mg NAC or placebo orally twice daily for 8 weeks. An intent-to-treat analysis using a repeated-measures logistic regression model was used to relate pretreatment impulsivity (Barratt Impulsiveness Scale) and treatment group to abstinence rates, measured by urine cannabinoid tests. To explore mechanisms by which NAC may reduce cannabis use, relationships between impulsivity, adherence, and abstinence were assessed in a second statistical model using data from participants with recorded adherence and urine cannabinoid test results (n = 54). Results In the intent-to-treat analysis, low pretreatment impulsivity, NAC treatment, and negative baseline urine cannabinoid test results independently increased the odds of having negative urine cannabinoid tests during treatment (OR = 2.1, 2.3, 5.3 respectively). In the sample of participants with adherence data (n = 54), adherence tripled the odds of abstinence. Notably, the effect of adherence on abstinence was only observed in the NAC treatment group. Lastly, although the highly impulsive participants had reduced rates of abstinence, highly impulsive individuals adherent to NAC treatment had increased abstinence rates compared to non-adherent individuals. Conclusion Low impulsivity, NAC treatment, medication adherence, and baseline negative cannabinoid testing were associated with increased rates of abstinence in adolescents seeking treatment for cannabis use disorder. Efforts to optimize pharmacotherapy adherence may be particularly crucial for highly impulsive individuals. Understanding and addressing factors, such as impulsivity and adherence, which may affect outcomes, may aid in the successful evaluation and development of potentially promising pharmacotherapies. PMID:26827257

Impact of monetary incentives on adherence to referral for screening chest x-rays after syringe exchange-based tuberculin skin testing.

PubMed

Perlman, David C; Friedmann, Patricia; Horn, Leslie; Nugent, Anne; Schoeb, Veronika; Carey, Jeanne; Salomon, Nadim; Des Jarlais, Don C

2003-09-01

Syringe-exchange programs (SEPs) have proven to be valuable sites to conduct tuberculin skin testing among active injection drug users. Chest x-rays (CXRs) are needed to exclude active tuberculosis prior to initiating treatment for latent tuberculosis infection. Adherence of drug users to referral for off-site chest x-rays has been incomplete. Previous cost modeling demonstrated that a monetary incentive to promote adherence could be justified on the cost basis if it had even a modest effect on adherence. We compared adherence to referral for chest x-rays among injection drug users undergoing syringe exchange-based tuberculosis screening in New York City before and after the implementation of monetary incentives. From 1995 to 1998, there were 119 IDUs referred for CXRs based on tuberculin skin testing at the SEP. From 1999 to 2001, there were 58 IDUs referred for CXRs with a $25 incentive based on adherence. Adherence to CXR referral within 7 days was 46/58 (79%) among individuals who received the monetary incentive versus 17/119 (14%) prior to the implementation of the monetary incentive (P<.0001; odds ratio [OR]=23; 95% confidence interval [CI]=9.5-57). The median time to obtaining a CXR was significantly shorter among those given the incentive than among those referred without the incentive (2 vs. 11 days, P<.0001). In multivariate logistic regression analysis, use of the incentive was highly independently associated with increased adherence (OR=22.9; 95% CI=10-52). Monetary incentives are highly effective in increasing adherence to referral for screening CXRs to exclude active tuberculosis after syringe exchange-based tuberculin skin testing. Prior cost modeling demonstrated that monetary incentives could be justified on the cost basis if they had even a modest effect on adherence. The current data demonstrated that monetary incentives are highly effective at increasing adherence in this setting and therefore are justifiable on a cost basis. When health care interventions for drug users require referral off site, monetary incentives may be particularly valuable in promoting adherence.

Examining the Link between Patient Satisfaction and Adherence to HIV Care: A Structural Equation Model

PubMed Central

Dang, Bich N.; Westbrook, Robert A.; Black, William C.; Rodriguez-Barradas, Maria C.; Giordano, Thomas P.

2013-01-01

Introduction Analogous to the business model of customer satisfaction and retention, patient satisfaction could serve as an innovative, patient-centered focus for increasing retention in HIV care and adherence to HAART, and ultimately HIV suppression. Objective To test, through structural equation modeling (SEM), a model of HIV suppression in which patient satisfaction influences HIV suppression indirectly through retention in HIV care and adherence to HAART. Methods We conducted a cross-sectional study of adults receiving HIV care at two clinics in Texas. Patient satisfaction was based on two validated items, one adapted from the Consumer Assessment of Healthcare Providers and Systems survey (“Would you recommend this clinic to other patients with HIV?) and one adapted from the Delighted-Terrible Scale, (“Overall, how do you feel about the care you got at this clinic in the last 12 months?”). A validated, single-item question measured adherence to HAART over the past 4 weeks. Retention in HIV care was based on visit constancy in the year prior to the survey. HIV suppression was defined as plasma HIV RNA <48 copies/mL at the time of the survey. We used SEM to test hypothesized relationships. Results The analyses included 489 patients (94% of eligible patients). The patient satisfaction score had a mean of 8.5 (median 9.2) on a 0- to 10- point scale. A total of 46% reported “excellent” adherence, 76% had adequate retention, and 70% had HIV suppression. In SEM analyses, patient satisfaction with care influences retention in HIV care and adherence to HAART, which in turn serve as key determinants of HIV suppression (all p<.0001). Conclusions Patient satisfaction may have direct effects on retention in HIV care and adherence to HAART. Interventions to improve the care experience, without necessarily targeting objective clinical performance measures, could serve as an innovative method for optimizing HIV outcomes. PMID:23382948

Sampling little fish in big rivers: Larval fish detection probabilities in two Lake Erie tributaries and implications for sampling effort and abundance indices

USGS Publications Warehouse

Pritt, Jeremy J.; DuFour, Mark R.; Mayer, Christine M.; Roseman, Edward F.; DeBruyne, Robin L.

2014-01-01

Larval fish are frequently sampled in coastal tributaries to determine factors affecting recruitment, evaluate spawning success, and estimate production from spawning habitats. Imperfect detection of larvae is common, because larval fish are small and unevenly distributed in space and time, and coastal tributaries are often large and heterogeneous. We estimated detection probabilities of larval fish from several taxa in the Maumee and Detroit rivers, the two largest tributaries of Lake Erie. We then demonstrated how accounting for imperfect detection influenced (1) the probability of observing taxa as present relative to sampling effort and (2) abundance indices for larval fish of two Detroit River species. We found that detection probabilities ranged from 0.09 to 0.91 but were always less than 1.0, indicating that imperfect detection is common among taxa and between systems. In general, taxa with high fecundities, small larval length at hatching, and no nesting behaviors had the highest detection probabilities. Also, detection probabilities were higher in the Maumee River than in the Detroit River. Accounting for imperfect detection produced up to fourfold increases in abundance indices for Lake Whitefish Coregonus clupeaformis and Gizzard Shad Dorosoma cepedianum. The effect of accounting for imperfect detection in abundance indices was greatest during periods of low abundance for both species. Detection information can be used to determine the appropriate level of sampling effort for larval fishes and may improve management and conservation decisions based on larval fish data.

The Effect of Social Support on Glycemic Control in Patients with Type 2 Diabetes Mellitus: The Mediating Roles of Self-Efficacy and Adherence

PubMed Central

Shao, Yechang; Liang, Lu; Shi, Linjing; Yu, Shouyi

2017-01-01

Ample evidence suggests that social support, self-efficacy, and adherence significantly, independently, and together affect glycemic control in patients with type 2 diabetes mellitus (T2DM), but the pathway from social support to glycemic control remains unclear. This study hypothesized that the effect of social support on glycemic control was mediated sequentially by self-efficacy and adherence. Patients with T2DM were recruited from two hospitals in Guangzhou, China, from January 1 to July 31, 2014, and their sociodemographic clinical data and their assessments on social support, self-efficacy, and adherence were obtained from medical records and self-completed questionnaires. Of the 532 patients who participated, 35% achieved glycemic control (i.e., HbA1c < 7%). Social support, self-efficacy, and adherence had significant correlations with each other and with glycemic control (P < 0.05). Regression analyses and structural equation modeling showed that better social support was associated to better patient self-efficacy, which, in turn, was associated with better medical adherence, which was associated with improved glycemic control, and the relationship between social support and glycemic control was sequentially and completely mediated by self-efficacy and adherence. The five goodness-of-fit indices confirmed that our data fitted the hypothesized pathway model strongly. PMID:28626769

Adherence to a Mediterranean diet and Alzheimer's disease risk in an Australian population

PubMed Central

Gardener, S; Gu, Y; Rainey-Smith, S R; Keogh, J B; Clifton, P M; Mathieson, S L; Taddei, K; Mondal, A; Ward, V K; Scarmeas, N; Barnes, M; Ellis, K A; Head, R; Masters, C L; Ames, D; Macaulay, S L; Rowe, C C; Szoeke, C; Martins, R N

2012-01-01

The Mediterranean diet (MeDi), due to its correlation with a low morbidity and mortality for many chronic diseases, has been widely recognised as a healthy eating model. We aimed to investigate, in a cross-sectional study, the association between adherence to a MeDi and risk for Alzheimer's disease (AD) and mild cognitive impairment (MCI) in a large, elderly, Australian cohort. Subjects in the Australian Imaging, Biomarkers and Lifestyle Study of Ageing cohort (723 healthy controls (HC), 98 MCI and 149 AD participants) completed the Cancer Council of Victoria Food Frequency Questionnaire. Adherence to the MeDi (0- to 9-point scale with higher scores indicating higher adherence) was the main predictor of AD and MCI status in multinominal logistic regression models that were adjusted for cohort age, sex, country of birth, education, apolipoprotein E genotype, total caloric intake, current smoking status, body mass index, history of diabetes, hypertension, angina, heart attack and stroke. There was a significant difference in adherence to the MeDi between HC and AD subjects (P<0.001), and in adherence between HC and MCI subjects (P<0.05). MeDi is associated with change in Mini-Mental State Examination score over an 18-month time period (P<0.05) in HCs. We conclude that in this Australian cohort, AD and MCI participants had a lower adherence to the MeDi than HC participants. PMID:23032941

A Prestressed Cable Network Model of the Adherent Cell Cytoskeleton

PubMed Central

Coughlin, Mark F.; Stamenović, Dimitrije

2003-01-01

A prestressed cable network is used to model the deformability of the adherent cell actin cytoskeleton. The overall and microstructural model geometries and cable mechanical properties were assigned values based on observations from living cells and mechanical measurements on isolated actin filaments, respectively. The models were deformed to mimic cell poking (CP), magnetic twisting cytometry (MTC) and magnetic bead microrheometry (MBM) measurements on living adherent cells. The models qualitatively and quantitatively captured the fibroblast cell response to the deformation imposed by CP while exhibiting only some qualitative features of the cell response to MTC and MBM. The model for CP revealed that the tensed peripheral actin filaments provide the key resistance to indentation. The actin filament tension that provides mechanical integrity to the network was estimated at ∼158 pN, and the nonlinear mechanical response during CP originates from filament kinematics. The MTC and MBM simulations revealed that the model is incomplete, however, these simulations show cable tension as a key determinant of the model response. PMID:12547813

A prestressed cable network model of the adherent cell cytoskeleton.

PubMed

Coughlin, Mark F; Stamenović, Dimitrije

2003-02-01

A prestressed cable network is used to model the deformability of the adherent cell actin cytoskeleton. The overall and microstructural model geometries and cable mechanical properties were assigned values based on observations from living cells and mechanical measurements on isolated actin filaments, respectively. The models were deformed to mimic cell poking (CP), magnetic twisting cytometry (MTC) and magnetic bead microrheometry (MBM) measurements on living adherent cells. The models qualitatively and quantitatively captured the fibroblast cell response to the deformation imposed by CP while exhibiting only some qualitative features of the cell response to MTC and MBM. The model for CP revealed that the tensed peripheral actin filaments provide the key resistance to indentation. The actin filament tension that provides mechanical integrity to the network was estimated at approximately 158 pN, and the nonlinear mechanical response during CP originates from filament kinematics. The MTC and MBM simulations revealed that the model is incomplete, however, these simulations show cable tension as a key determinant of the model response.

Characteristics and model of sludge adhesion during thermal drying.

PubMed

Li, Huan; Zou, Shuxin; Li, Yangyang; Jin, Yiying

2013-01-01

During sludge thermal drying, the sludge adhered on the heated surface of drying equipments may affect drying efficiency. Sludge thermal drying experiments were conducted to investigate the effect of different drying conditions on sludge adhesion. The mass of sludge adhered on the heated surface (dryer wall) reached the maximum when sludge water content was about 60%. A high drying temperature would result in more sludge adhered on the heated surface in the temperature range of 80-160 degrees C. The convection heating and rougher surface would also lead to more sludge adhered on the heated surface. The relation between the maximum mass of adherent sludge and drying temperatures could be described by an exponential equation.

High-throughput sequencing of small RNAs and analysis of differentially expressed microRNAs associated with pistil development in Japanese apricot

PubMed Central

2012-01-01

Background MicroRNAs (miRNAs) are a class of endogenous, small, non-coding RNAs that regulate gene expression by mediating gene silencing at transcriptional and post-transcriptional levels in high plants. However, the diversity of miRNAs and their roles in floral development in Japanese apricot (Prunus mume Sieb. et Zucc) remains largely unexplored. Imperfect flowers with pistil abortion seriously decrease production yields. To understand the role of miRNAs in pistil development, pistil development-related miRNAs were identified by Solexa sequencing in Japanese apricot. Results Solexa sequencing was used to identify and quantitatively profile small RNAs from perfect and imperfect flower buds of Japanese apricot. A total of 22,561,972 and 24,952,690 reads were sequenced from two small RNA libraries constructed from perfect and imperfect flower buds, respectively. Sixty-one known miRNAs, belonging to 24 families, were identified. Comparative profiling revealed that seven known miRNAs exhibited significant differential expression between perfect and imperfect flower buds. A total of 61 potentially novel miRNAs/new members of known miRNA families were also identified by the presence of mature miRNAs and corresponding miRNA*s in the sRNA libraries. Comparative analysis showed that six potentially novel miRNAs were differentially expressed between perfect and imperfect flower buds. Target predictions of the 13 differentially expressed miRNAs resulted in 212 target genes. Gene ontology (GO) annotation revealed that high-ranking miRNA target genes are those implicated in the developmental process, the regulation of transcription and response to stress. Conclusions This study represents the first comparative identification of miRNAomes between perfect and imperfect Japanese apricot flowers. Seven known miRNAs and six potentially novel miRNAs associated with pistil development were identified, using high-throughput sequencing of small RNAs. The findings, both computationally and experimentally, provide valuable information for further functional characterisation of miRNAs associated with pistil development in plants. PMID:22863067

Development of a scale to measure adherence to self-monitoring of blood glucose with latent variable measurement.

PubMed

Wagner, J A; Schnoll, R A; Gipson, M T

1998-07-01

Adherence to self-monitoring of blood glucose (SMBG) is problematic for many people with diabetes. Self-reports of adherence have been found to be unreliable, and existing paper-and-pencil measures have limitations. This study developed a brief measure of SMBG adherence with good psychometric properties and a useful factor structure that can be used in research and in practice. A total of 216 adults with diabetes responded to 30 items rated on a 9-point Likert scale that asked about blood monitoring habits. In part I of the study, items were evaluated and retained based on their psychometric properties. The sample was divided into exploratory and confirmatory halves. Using the exploratory half, items with acceptable psychometric properties were subjected to a principal components analysis. In part II of the study, structural equation modeling was used to confirm the component solution with the entire sample. Structural modeling was also used to test the relationship between these components. It was hypothesized that the scale would produce four correlated factors. Principal components analysis suggested a two-component solution, and confirmatory factor analysis confirmed this solution. The first factor measures the degree to which patients rely on others to help them test and thus was named "social influence." The second component measures the degree to which patients use physical symptoms of blood glucose levels to help them test and thus was named "physical influence." Results of the structural model show that the components are correlated and make up the higher-order latent variable adherence. The resulting 15-item scale provides a short, reliable way to assess patient adherence to SMBG. Despite the existence of several aspects of adherence, this study indicates that the construct consists of only two components. This scale is an improvement on previous measures of adherence because of its good psychometric properties, its interpretable factor structure, and its rigorous empirical development.

Analysis of Endothelial Adherence of Bartonella henselae and Acinetobacter baumannii Using a Dynamic Human Ex Vivo Infection Model

PubMed Central

Weidensdorfer, Marko; Chae, Ju Ik; Makobe, Celestine; Stahl, Julia; Averhoff, Beate; Müller, Volker; Schürmann, Christoph; Brandes, Ralf P.; Wilharm, Gottfried; Ballhorn, Wibke; Christ, Sara; Linke, Dirk; Fischer, Doris; Göttig, Stephan

2015-01-01

Bacterial adherence determines the virulence of many human-pathogenic bacteria. Experimental approaches elucidating this early infection event in greater detail have been performed using mainly methods of cellular microbiology. However, in vitro infections of cell monolayers reflect the in vivo situation only partially, and animal infection models are not available for many human-pathogenic bacteria. Therefore, ex vivo infection of human organs might represent an attractive method to overcome these limitations. We infected whole human umbilical cords ex vivo with Bartonella henselae or Acinetobacter baumannii under dynamic flow conditions mimicking the in vivo infection situation of human endothelium. For this purpose, methods for quantifying endothelium-adherent wild-type and trimeric autotransporter adhesin (TAA)-deficient bacteria were set up. Data revealed that (i) A. baumannii binds in a TAA-dependent manner to endothelial cells, (ii) this organ infection model led to highly reproducible adherence rates, and furthermore, (iii) this model allowed to dissect the biological function of TAAs in the natural course of human infections. These findings indicate that infection models using ex vivo human tissue samples (“organ microbiology”) might be a valuable tool in analyzing bacterial pathogenicity with the capacity to replace animal infection models at least partially. PMID:26712205

Effects of sociodemographic characteristics and patients' health beliefs on tuberculosis treatment adherence in Ethiopia: a structural equation modelling approach.

PubMed

Tola, Habteyes Hailu; Karimi, Mehrdad; Yekaninejad, Mir Saeed

2017-12-15

Patients' beliefs are a major factor affecting tuberculosis (TB) treatment adherence. However, there has been little use of Health Belief Model (HBM) in determining the pathway effect of patients' sociodemographic characteristics and beliefs on TB treatment adherence. Therefore, this study was aimed at determining the effect of sociodemographic characteristics and patients' health beliefs on TB treatment adherence based on the HBM concept in Ethiopia. A cross-sectional study was conducted in Addis Ababa, Ethiopia among TB patients undertaking treatment. Thirty health centres were randomly selected and one hospital was purposely chosen. Six hundred and ninety-eight TB patients who had been on treatment for 1-2 month, were aged 18 years or above, and had the mental capability to provide consent were enrolled consecutively with non-probability sampling technique from the TB registration book until required sample size achieved. Structured questionnaires were used to collect data. Structural equation modelling was employed to assess the pathway relationship between sociodemographic characteristics, patients' beliefs, and treatment adherence. Of the 698 enrolled participants, 401 (57.4%) were male and 490 (70.2%) were aged 35 years and below. The mean age of participants was 32 (± 11.7) and the age range was 18-90 years. Perceived barrier/benefit was shown to be a significant direct negative effect on TB treatment adherence (ß = -0.124, P = 0.032). In addition, cue to action (ß = -0.68, P ≤ 0.001) and psychological distress (ß = 0.08, P < 0.001) were shown significant indirect effects on TB treatment adherence through perceived barrier/benefit. Interventions intended to decrease perceived barriers and maximize perceived benefits should be implemented to enhance TB treatment adherence. In addition, it is crucial that counselling is incorporated with the regular directly observed therapy program. Motivators (cue to actions) such as friends, family, healthcare workers, and the media could be used to promote TB treatment adherence.

Theoretical analysis and modeling of a photonic integrated circuit for frequency 8-tupled and 24-tupled millimeter wave signal generation.

PubMed

Hasan, Mehedi; Guemri, Rabiaa; Maldonado-Basilio, Ramón; Lucarz, Frédéric; de Bougrenet de la Tocnaye, Jean-Louis; Hall, Trevor

2014-12-15

A photonic circuit design for implementing frequency 8-tupling and 24-tupling is proposed. The front- and back-end of the circuit comprises 4×4 MMI couplers enclosing an array of four pairs of phase modulators and 2×2 MMI couplers. The proposed design for frequency multiplication requires no optical or electrical filters, the operation is not limited to carefully adjusted modulation indexes, and the drift originated from static DC bias is mitigated by making use of the intrinsic phase relations of multi-mode interference couplers. A transfer matrix approach is used to represent the main building blocks of the design and hence to describe the operation of the frequency 8-tupling and 24-tupling. The concept is theoretically developed and demonstrated by simulations. Ideal and imperfect power imbalances in the multi-mode interference couplers, as well as ideal and imperfect phases of the electric drives to the phase modulators, are analyzed.

Effects of Optical-density and Phase Dispersion of an Imperfect Band-limited Occulting Mask on the Broadband Performance of a TPF Coronagraph

NASA Technical Reports Server (NTRS)

Sidiek, Erkin; Balasubramanian, Kunjithapatham

2007-01-01

Practical image-plane occulting masks required by high-contrast imaging systems such as the TPF-Coronagraph introduce phase errors into the transmitting beam., or, equivalently, diffracts the residual starlight into the area of the final image plane used for detecting exo-planets. Our group at JPL has recently proposed spatially Profiled metal masks that can be designed to have zero parasitic phase at the center wavelength of the incoming broadband light with small amounts of' 00 and phase dispersions at other wavelengths. Work is currently underway to design. fabricate and characterize such image-plane masks. In order to gain some understanding on the behaviors of these new imperfect band-limited occulting masks and clarify how such masks utilizing different metals or alloys compare with each other, we carried out some modeling and simulations on the contrast performance of the high-contrast imaging testbed (HCIT) at .JPL. In this paper we describe the details of our simulations and present our results.

Imperfect Vaccine Aggravates the Long-Standing Dilemma of Voluntary Vaccination

PubMed Central

Wu, Bin; Fu, Feng; Wang, Long

2011-01-01

Achieving widespread population immunity by voluntary vaccination poses a major challenge for public health administration and practice. The situation is complicated even more by imperfect vaccines. How the vaccine efficacy affects individuals' vaccination behavior has yet to be fully answered. To address this issue, we combine a simple yet effective game theoretic model of vaccination behavior with an epidemiological process. Our analysis shows that, in a population of self-interested individuals, there exists an overshooting of vaccine uptake levels as the effectiveness of vaccination increases. Moreover, when the basic reproductive number, , exceeds a certain threshold, all individuals opt for vaccination for an intermediate region of vaccine efficacy. We further show that increasing effectiveness of vaccination always increases the number of effectively vaccinated individuals and therefore attenuates the epidemic strain. The results suggest that ‘number is traded for efficiency’: although increases in vaccination effectiveness lead to uptake drops due to free-riding effects, the impact of the epidemic can be better mitigated. PMID:21687680

Effect of Surface Imperfections and Excrescences on the Crossflow Instability

NASA Astrophysics Data System (ADS)

Tufts, Matthew; Duncan, Glen, Jr.; Crawford, Brian; Reed, Helen; Saric, William

2012-11-01

Presented is analysis of the planned SWIFTER experiment to be flown on Texas A&M University's O-2A aircraft. Simultaneous control of the crossflow and streamwise boundary-layer instabilities is a challenge for laminar flow control on swept wings. Solving this problem is an active area of research, with a specific need to quantify the effect of surface imperfections and outer mold line excrescences on crossflow instabilities. The SWIFTER test article is a modification of a prior-tested flight model, with the additional capability of creating controlled excrescences in flight. Using a finite-element Navier-Stokes solution and a spectrally accurate boundary-layer solver, coupled with linear and nonlinear stability analyses, we show that the flow field over the test article is well suited to this study. Results are compared with flight data. The work is supported by the Air Force Research Laboratory through General Dynamics Information Technology, Inc. under sub Agreement No USAF-3446-11-50-SC-01 and the Texas A&M Supercomputing Facility.

A study of astrometric distortions due to “tree rings” in CCD sensors using LSST Photon Simulator

DOE PAGES

Beamer, Benjamin; Nomerotski, Andrei; Tsybychev, Dmitri

2015-05-22

Imperfections in the production process of thick CCDs lead to circularly symmetric dopant concentration variations, which in turn produce electric fields transverse to the surface of the fully depleted CCD that displace the photogenerated charges. We use PhoSim, a Monte Carlo photon simulator, to explore and examine the likely impacts these dopant concentration variations will have on astrometric measurements in LSST. The scale and behavior of both the astrometric shifts imparted to point sources and the intensity variations in flat field images that result from these doping imperfections are similar to those previously observed in Dark Energy Camera CCDs, givingmore » initial confirmation of PhoSim's model for these effects. In addition, the organized shape distortions were observed as a result of the symmetric nature of these dopant variations, causing nominally round sources to be imparted with a measurable ellipticity either aligned with or transverse to the radial direction of this dopant variation pattern.« less

QuickPol: Fast calculation of effective beam matrices for CMB polarization

NASA Astrophysics Data System (ADS)

Hivon, Eric; Mottet, Sylvain; Ponthieu, Nicolas

2017-02-01

Current and planned observations of the cosmic microwave background (CMB) polarization anisotropies, with their ever increasing number of detectors, have reached a potential accuracy that requires a very demanding control of systematic effects. While some of these systematics can be reduced in the design of the instruments, others will have to be modeled and hopefully accounted for or corrected a posteriori. We propose QuickPol, a quick and accurate calculation of the full effective beam transfer function and of temperature to polarization leakage at the power spectra level, as induced by beam imperfections and mismatches between detector optical and electronic responses. All the observation details such as exact scanning strategy, imperfect polarization measurements, and flagged samples are accounted for. Our results are validated on Planck high frequency instrument (HFI) simulations. We show how the pipeline can be used to propagate instrumental uncertainties up to the final science products, and could be applied to experiments with rotating half-wave plates.

Grammatical aspect, lexical aspect, and event duration constrain the availability of events in narratives.

PubMed

Becker, Raymond B; Ferretti, Todd R; Madden-Lombardi, Carol J

2013-11-01

The present study investigates how readers' representations of narratives are constrained by three sources of temporal information; grammatical aspect, lexical aspect, and the duration of intervening events. Participants read short stories in which a target event with an intrinsic endpoint or not (lexical aspect: accomplishments/activities) was described as ongoing or completed (grammatical aspect: imperfective/perfective). An intervening sentence described either a long or short duration event before the target situation was reintroduced later in the story. The electroencephalogram time-locked to the reintroduction of the target event elicited a larger N400 for perfective versus imperfective accomplishments, and this effect occurred only after short intervening events. Alternatively, the N400 to targets in the activity condition did not vary as a function of grammatical aspect or duration of intervening events. These results provide novel insight into how the temporal properties of events interact to constrain the availability of concepts in situation models. Copyright © 2013 Elsevier B.V. All rights reserved.

Rapid Measurement and Correction of Phase Errors from B0 Eddy Currents: Impact on Image Quality for Non-Cartesian Imaging

PubMed Central

Brodsky, Ethan K.; Klaers, Jessica L.; Samsonov, Alexey A.; Kijowski, Richard; Block, Walter F.

2014-01-01

Non-Cartesian imaging sequences and navigational methods can be more sensitive to scanner imperfections that have little impact on conventional clinical sequences, an issue which has repeatedly complicated the commercialization of these techniques by frustrating transitions to multi-center evaluations. One such imperfection is phase errors caused by resonant frequency shifts from eddy currents induced in the cryostat by time-varying gradients, a phenomemon known as B0 eddy currents. These phase errors can have a substantial impact on sequences that use ramp sampling, bipolar gradients, and readouts at varying azimuthal angles. We present a method for measuring and correcting phase errors from B0 eddy currents and examine the results on two different scanner models. This technique yields significant improvements in image quality for high-resolution joint imaging on certain scanners. The results suggest that correction of short time B0 eddy currents in manufacturer provided service routines would simplify adoption of non-Cartesian sampling methods. PMID:22488532

Teaching Academic Integrity: A Cognitive Developmental Model Based on Kohlberg's Theory of Moral Development.

ERIC Educational Resources Information Center

Peterson, Lorna

An instructional model to develop academic integrity (honesty) in college students is proposed. Goals are to develop: adherence to the principle of doing one's own work, an understanding for the principle and nature of coauthorship, an understanding and adherence to citation practices, and an understanding of plagiarism. Students should be…

Pathways From HIV-Related Stigma to Antiretroviral Therapy Measures in the HIV Care Cascade for Women Living With HIV in Canada.

PubMed

Logie, Carmen H; Lacombe-Duncan, Ashley; Wang, Ying; Kaida, Angela; Conway, Tracey; Webster, Kath; de Pokomandy, Alexandra; Loutfy, Mona R; Anema, Aranka; Becker, Denise; Brotto, Lori; Carter, Allison; Cardinal, Claudette; Colley, Guillaume; Ding, Erin; Duddy, Janice; Gataric, Nada; Hogg, Robert S; Hosward, Terry; Jabbari, Shahab; Jones, Evin; Kestler, Mary; Langlois, Andrea; Lima, Viviane; Lloyd-Smith, Elisa; Medjuck, Melissa; Miller, Cari; Money, Deborah; Nicholson, Valerie; Ogilvie, Gina; Patterson, Sophie; Pick, Neora; Roth, Eric; Salters, Kate; Sanchez, Margarite; Sas, Jacquie; Sereda, Paul; Summers, Marcie; Tom, Christina; Wang, Lu; Webster, Kath; Zhang, Wendy; Abdul-Noor, Rahma; Angel, Jonathan; Barry, Fatimatou; Bauer, Greta; Beaver, Kerrigan; Benoit, Anita; Bertozzi, Breklyn; Borton, Sheila; Bourque, Tammy; Brophy, Jason; Burchell, Ann; Carlson, Allison; Cioppa, Lynne; Cohen, Jeffrey; Conway, Tracey; Cooper, Curtis; Cotnam, Jasmine; Cousineau, Janette; Fraleigh, Annette; Gagnier, Brenda; Gasingirwa, Claudine; Greene, Saara; Hart, Trevor; Islam, Shazia; Kaushic, Charu; Kennedy, Logan; Kerr, Desiree; Kiboyogo, Maxime; Kwaramba, Gladys; Leonard, Lynne; Lewis, Johanna; Logie, Carmen; Margolese, Shari; Muchenje, Marvelous; Ndungʼu, Mary; OʼBrien, Kelly; Ouellette, Charlene; Powis, Jeff; Quan, Corinna; Raboud, Janet; Rachlis, Anita; Ralph, Edward; Rourke, Sean; Rueda, Sergio; Sandre, Roger; Smaill, Fiona; Smith, Stephanie; Tigere, Tsitsi; Tharao, Wangari; Walmsley, Sharon; Wobeser, Wendy; Yee, Jessica; Yudin, Mark; Baril, Jean-Guy; Burke, Nora Butler; Clément, Pierrette; Dayle, Janice; Dubuc, Danièle; Fernet, Mylène; Groleau, Danielle; Hot, Aurélie; Klein, Marina; Martin, Carrie; Massie, Lyne; Ménard, Brigitte; OʼBrien, Nadia; Otis, Joanne; Peltier, Doris; Pierre, Alie; Proulx-Boucher, Karène; Rouleau, Danielle; Savoie, Édénia; Tremblay, Cécile; Trottier, Benoit; Trottier, Sylvie; Tsoukas, Christos; Gahagan, Jacqueline; Hankins, Catherine; Masching, Renee; Ogunnaike-Cooke, Susanna

2018-02-01

Associations between HIV-related stigma and reduced antiretroviral therapy (ART) adherence are widely established, yet the mechanisms accounting for this relationship are underexplored. There has been less attention to HIV-related stigma and its associations with ART initiation and current ART use. We examined pathways from HIV-related stigma to ART initiation, current ART use, and ART adherence among women living with HIV in Canada. We used baseline survey data from a national cohort of women living with HIV in Canada (n = 1425). Structural equation modeling using weighted least squares estimation methods was conducted to test the direct effects of HIV-related stigma dimensions (personalized, negative self-image, and public attitudes) on ART initiation, current ART use, and 90% ART adherence, and indirect effects through depression and HIV disclosure concerns, adjusting for sociodemographic factors. In the final model, the direct paths from personalized stigma to ART initiation (β = -0.104, P < 0.05) and current ART use (β = -0.142, P < 0.01), and negative self-image to ART initiation (β = -0.113, P < 0.01) were significant, accounting for the mediation effects of depression and HIV disclosure concerns. Depression mediated the pathways from personalized stigma to ART adherence, and negative self-image to current ART use and ART adherence. Final model fit indices suggest that the model fit the data well [χ(25) = 90.251, P < 0.001; comparative fit index = 0.945; root-mean-square error of approximation = 0.044]. HIV-related stigma is associated with reduced likelihood of ART initiation and current ART use, and suboptimal ART adherence. To optimize the benefit of ART among women living with HIV, interventions should reduce HIV-related stigma and address depression.

Predictors of Change in Adherence Status from 1 Year to the Next Among Patients with Type 2 Diabetes Mellitus on Oral Antidiabetes Drugs.

PubMed

Saundankar, Vishal; Peng, Xiaomei; Fu, Haoda; Ascher-Svanum, Haya; Rodriguez, Angel; Ali, Ayad; Slabaugh, Lane; Young, Peinie; Louder, Anthony

2016-05-01

Diabetes is a leading cause of morbidity, mortality, and medical resource utilization in the United States and worldwide. Treatment is aimed at keeping blood glucose levels close to normal and preventing or delaying medical complications. It has been estimated that only 50% of patients with diabetes in the United States achieve glycosylated hemoglobin A1c level < 7%. Nonadherence to antidiabetic medications has been identified as a major factor related to poor glycemic control. To (a) assess adult patients with type 2 diabetes mellitus (T2DM) whose adherence status to oral antidiabetic drugs (OADs) changed from 1 year to the next and (b) identify predictors of change in adherence status. This retrospective study of the Humana Medicare Advantage Database included patients with T2DM and continuous enrollment between 2010 and 2012. Proportion of days covered (PDC) by OADs was calculated for each of the 3 study years (2010, 2011, 2012). Patients were classified as adherent (PDC ≥ 80%) or nonadherent (PDC < 80%) during each year. Patient characteristics from the baseline period (2010) were used as covariates, and adherence status changes from baseline to follow-up year (2011) were used as response variables. Data from the subsequent study periods (2011 as baseline, 2012 as follow-up) were used to validate the model (final model). A total of 238,402 patients met inclusion criteria. Among them, 144,216 (60.5%) were adherent, and 94,186 (39.5%) were nonadherent during the baseline period. Change in adherence status from baseline to follow-up year was observed in 31,320 (21.7%) patients that were adherent and 39,284 (41.7%) patients that were nonadherent during the baseline year. The final model for baseline adherent patients had a receiver-operating characteristic (ROC) index of 73% and a misclassification rate of 39%. The predictors of highest importance were identified as total number of prescriptions filled with 90-day supply, diabetes-related pill burden, longest gap in OADs, total number of antidiabetic classes filled, and copay for the last OAD filled. The final model had a sensitivity value of 76.4%. The final model for baseline nonadherent patients had a ROC index of 68%, a misclassification rate of 36.4%, and sensitivity value of 52.9%. The predictors of highest importance were diabetes-related pill burden, longest gap in OADs, month-wise patient oscillation from adherent to nonadherent during baseline year, total number of prescriptions filled with a 90-day supply, and total pill burden during the baseline year. One third of the T2DM patients changed adherence status from 1 year to the next, and factors associated with adherence status changes were identified. Predictive models such as those used in this study can serve as useful and cost-effective tools for payers, helping to identify members that should be targeted for adherence enhancement programs and, ultimately, to improve patients' long-term outcomes. Funding for this research was provided by Eli Lilly and Company. Comprehensive Health Insights, owned by Humana, completed this study. Peng, Fu, Ascher-Svanum, Ali, and Rodriguez are employees of Eli Lilly and Company. Saundankar and Louder are employed by Comprehensive Health Insights, and Slabaugh and Young are employed by Humana. Study concept and design were contributed by Peng, Ascher-Svanum, and Young. Saundankar and Louder took the lead in data collection, while Saundankar, Peng, Fu, and Louder interpreted the data. The manuscript was written by Saundankar, Peng, Fu, and Louder and revised by Saundankar, Rodriguez, Ali, and Louder.

Medication adherence and stroke/TIA risk in treated hypertensives: results from the REGARDS study.

PubMed

Cummings, Doyle M; Letter, Abraham J; Howard, George; Howard, Virginia J; Safford, Monika M; Prince, Valerie; Muntner, Paul

2013-01-01

The extent to which low medication adherence in hypertensive individuals contributes to disparities in stroke and transient ischemic attack (TIA) risk is poorly understood. Investigators examined the relationship between self-reported medication adherence and blood pressure (BP) control (<140/90 mm Hg), Framingham Stroke Risk Score, and physician-adjudicated stroke/TIA incidence in treated hypertensive subjects (n = 15,071; 51% black; 57% in Stroke Belt) over 4.9 years in the national population-based REGARDS cohort study. Mean systolic BP varied from 130.8 ± 16.2 mm Hg in those reporting high adherence to 137.8 ± 19.5 mm Hg in those reporting low adherence (P for trend < .0001). In logistic regression models, each level of worsening medication adherence was associated with significant and increasing odds of inadequately controlled BP (≥140/90 mm Hg; score = 1, odds ratio [95% confidence interval], 1.20 [1.09-1.30]; score = 2, 1.27 [1.08-1.49]; score = 3 or 4, 2.21 [1.75-2.78]). In hazard models using systolic BP as a mediator, those reporting low medication adherence had 1.08 (1.04-1.14) times greater risk of stroke and 1.08 (1.03-1.12) times greater risk of stroke or TIA. Low medication adherence was associated with inadequate BP control and an increased risk of incident stroke or TIA. Copyright © 2013 American Society of Hypertension. Published by Elsevier Inc. All rights reserved.

Predicting adherence to eye patching in children with amblyopia: an application of protection motivation theory.

PubMed

Norman, Paul; Searle, Aidan; Harrad, Richard; Vedhara, Kav

2003-02-01

This study reports an application of protection motivation theory (PMT) to the prediction of parental adherence to eye patching recommendations for children with amblyopia over a 2-month period. The study also considered the role of past behaviour in PMT. A total of 151 parents of children with amblyopia who were attending follow-up appointments for orthoptic treatment participated. They completed questionnaires based on PMT to assess their beliefs about amblyopia and eye patching. Of the parents, 105 were contacted again at 2-month follow-up to obtain a measure of adherence to the recommended treatment for their child. PMT was found to be predictive of adherence intentions and behaviour at 2-month follow-up. Regression analyses revealed perceived vulnerability, response efficacy and self-efficacy to be significant predictors of protection motivation, whereas perceived vulnerability and response costs were significant predictors of adherence behaviour. Past adherence behaviour was found to have a direct effect on future adherence behaviour over and above the influence of PMT. The results are discussed in relation to the sufficiency of PMTas a model of adherence behaviour. The practical implications for attempts to increase adherence to eye patching among children with amblyopia are outlined.

Association between Spirituality and Adherence to Management in Outpatients with Heart Failure

PubMed Central

Alvarez, Juglans Souto; Goldraich, Livia Adams; Nunes, Alice Hoefel; Zandavalli, Mônica Cristina Brugalli; Zandavalli, Rafaela Brugalli; Belli, Karlyse Claudino; da Rocha, Neusa Sica; Fleck, Marcelo Pio de Almeida; Clausell, Nadine

2016-01-01

Background Spirituality may influence how patients cope with their illness. Objectives We assessed whether spirituality may influence adherence to management of outpatients with heart failure. Methods Cross sectional study enrolling consecutive ambulatory heart failure patients in whom adherence to multidisciplinary treatment was evaluated. Patients were assessed for quality of life, depression, religiosity and spirituality utilizing validated questionnaires. Correlations between adherence and psychosocial variables of interest were obtained. Logistic regression models explored independent predictors of adherence. Results One hundred and thirty patients (age 60 ± 13 years; 67% male) were interviewed. Adequate adherence score was observed in 38.5% of the patients. Neither depression nor religiosity was correlated to adherence, when assessed separately. Interestingly, spirituality, when assessed by both total score sum (r = 0.26; p = 0.003) and by all specific domains, was positively correlated to adherence. Finally, the combination of spirituality, religiosity and personal beliefs was an independent predictor of adherence when adjusted for demographics, clinical characteristics and psychosocial instruments. Conclusion Spirituality, religiosity and personal beliefs were the only variables consistently associated with compliance to medication in a cohort of outpatients with heart failure. Our data suggest that adequately addressing these aspects on patient’s care may lead to an improvement in adherence patterns in the complex heart failure management. PMID:27192385

Association between Spirituality and Adherence to Management in Outpatients with Heart Failure.

PubMed

Alvarez, Juglans Souto; Goldraich, Livia Adams; Nunes, Alice Hoefel; Zandavalli, Mônica Cristina Brugalli; Zandavalli, Rafaela Brugalli; Belli, Karlyse Claudino; Rocha, Neusa Sica da; Fleck, Marcelo Pio de Almeida; Clausell, Nadine

2016-06-01

Spirituality may influence how patients cope with their illness. We assessed whether spirituality may influence adherence to management of outpatients with heart failure. Cross sectional study enrolling consecutive ambulatory heart failure patients in whom adherence to multidisciplinary treatment was evaluated. Patients were assessed for quality of life, depression, religiosity and spirituality utilizing validated questionnaires. Correlations between adherence and psychosocial variables of interest were obtained. Logistic regression models explored independent predictors of adherence. One hundred and thirty patients (age 60 ± 13 years; 67% male) were interviewed. Adequate adherence score was observed in 38.5% of the patients. Neither depression nor religiosity was correlated to adherence, when assessed separately. Interestingly, spirituality, when assessed by both total score sum (r = 0.26; p = 0.003) and by all specific domains, was positively correlated to adherence. Finally, the combination of spirituality, religiosity and personal beliefs was an independent predictor of adherence when adjusted for demographics, clinical characteristics and psychosocial instruments. Spirituality, religiosity and personal beliefs were the only variables consistently associated with compliance to medication in a cohort of outpatients with heart failure. Our data suggest that adequately addressing these aspects on patient's care may lead to an improvement in adherence patterns in the complex heart failure management.

Patient-Oncologist Alliance, Psychosocial Well-Being, and Treatment Adherence Among Young Adults With Advanced Cancer

PubMed Central

Trevino, Kelly M.; Fasciano, Karen; Prigerson, Holly G.

2013-01-01

Purpose Patients who develop a strong alliance with their health care providers have been shown to have higher levels of psychosocial well-being and rates of treatment adherence. Young adults with cancer have lower levels of psychosocial well-being and treatment adherence relative to patients with cancer in other age groups. This study sought to evaluate the relationships between the patient-oncologist alliance, psychosocial well-being, and treatment adherence in young adults with advanced cancer. Patients and Methods Ninety-five young adults (age 20 to 40 years) with advanced cancer were administered measures of alliance, psychosocial well-being, willingness to adhere to treatment, and treatment adherence. Relationships between alliance and psychosocial well-being were examined bivariately. Multiple linear regression models examined the relationship between alliance and adherence, controlling for confounding influences (eg, psychosocial well-being). Results Alliance was significantly (P ≤ .01) and positively associated with greater perceived social support and less severe illness-related grief. After controlling for significant confounding influences (ie, metastases, appraised support, and grief), alliance remained significantly (P ≤ .01) associated with greater willingness to adhere to treatment and greater adherence to oral medication. Conclusion By developing a strong alliance, oncologists may enhance psychosocial well-being and increase treatment adherence in young adult patients with advanced cancer. PMID:23530105

Content analysis of antiretroviral adherence enhancing interview reports.

PubMed

Kamal, Susan; Nulty, Paul; Bugnon, Olivier; Cavassini, Matthias; Schneider, Marie P

2018-05-17

To identify factors associated with low or high antiretroviral (ARV) adherence through computational text analysis of an adherence enhancing programme interview reports. Using text from 8428 interviews with 522 patients, we constructed a term-frequency matrix for each patient, retaining words that occurred at least ten times overall and used in at least six interviews with six different patients. The text included both the pharmacist's and the patient's verbalizations. We investigated their association with an adherence threshold (above or below 90%) using a regularized logistic regression model. In addition to this data-driven approach, we studied the contexts of words with a focus group. Analysis resulted in 7608 terms associated with low or high adherence. Terms associated with low adherence included disruption in daily schedule, side effects, socio-economic factors, stigma, cognitive factors and smoking. Terms associated with high adherence included fixed medication intake timing, no side effects and positive psychological state. Computational text analysis helps to analyze a large corpus of adherence enhancing interviews. It confirms main known themes affecting ARV adherence and sheds light on new emerging themes. Health care providers should be aware of factors that are associated with low or high adherence. This knowledge should reinforce the supporting factors and try to resolve the barriers together with the patient. Copyright © 2018 Elsevier B.V. All rights reserved.

Cost Effectiveness of Potential ART Adherence Monitoring Interventions in Sub-Saharan Africa.

PubMed

Phillips, Andrew N; Cambiano, Valentina; Nakagawa, Fumiyo; Bansi-Matharu, Loveleen; Sow, Papa Salif; Ehrenkranz, Peter; Ford, Deborah; Mugurungi, Owen; Apollo, Tsitsi; Murungu, Joseph; Bangsberg, David R; Revill, Paul

2016-01-01

Interventions based around objective measurement of adherence to antiretroviral drugs for HIV have potential to improve adherence and to enable differentiation of care such that clinical visits are reduced in those with high adherence. It would be useful to understand the approximate upper limit of cost that could be considered for such interventions of a given effectiveness in order to be cost effective. Such information can guide whether to implement an intervention in the light of a trial showing a certain effectiveness and cost. An individual-based model, calibrated to Zimbabwe, which incorporates effects of adherence and resistance to antiretroviral therapy, was used to model the potential impact of adherence monitoring-based interventions on viral suppression, death rates, disability adjusted life years and costs. Potential component effects of the intervention were: enhanced average adherence when on ART, reduced risk of ART discontinuation, and reduced risk of resistance acquisition. We considered a situation in which viral load monitoring is not available and one in which it is. In the former case, it was assumed that care would be differentiated based on the adherence level, with fewer clinic visits in those demonstrated to have high adherence. In the latter case, care was assumed to be primarily differentiated according to viral load level. The maximum intervention cost required to be cost effective was calculated based on a cost effectiveness threshold of $500 per DALY averted. In the absence of viral load monitoring, an adherence monitoring-based intervention which results in a durable 6% increase in the proportion of ART experienced people with viral load < 1000 cps/mL was cost effective if it cost up to $50 per person-year on ART, mainly driven by the cost savings of differentiation of care. In the presence of viral load monitoring availability, an intervention with a similar effect on viral load suppression was cost-effective when costing $23-$32 per year, depending on whether the adherence intervention is used to reduce the level of need for viral load measurement. The cost thresholds identified suggest that there is clear scope for adherence monitoring-based interventions to provide net population health gain, with potential cost-effective use in situations where viral load monitoring is or is not available. Our results guide the implementation of future adherence monitoring interventions found in randomized trials to have health benefit.

Cost Effectiveness of Potential ART Adherence Monitoring Interventions in Sub-Saharan Africa

PubMed Central

Cambiano, Valentina; Nakagawa, Fumiyo; Bansi-Matharu, Loveleen; Sow, Papa Salif; Ehrenkranz, Peter; Ford, Deborah; Mugurungi, Owen; Apollo, Tsitsi; Murungu, Joseph; Bangsberg, David R.; Revill, Paul

2016-01-01

Background Interventions based around objective measurement of adherence to antiretroviral drugs for HIV have potential to improve adherence and to enable differentiation of care such that clinical visits are reduced in those with high adherence. It would be useful to understand the approximate upper limit of cost that could be considered for such interventions of a given effectiveness in order to be cost effective. Such information can guide whether to implement an intervention in the light of a trial showing a certain effectiveness and cost. Methods An individual-based model, calibrated to Zimbabwe, which incorporates effects of adherence and resistance to antiretroviral therapy, was used to model the potential impact of adherence monitoring-based interventions on viral suppression, death rates, disability adjusted life years and costs. Potential component effects of the intervention were: enhanced average adherence when on ART, reduced risk of ART discontinuation, and reduced risk of resistance acquisition. We considered a situation in which viral load monitoring is not available and one in which it is. In the former case, it was assumed that care would be differentiated based on the adherence level, with fewer clinic visits in those demonstrated to have high adherence. In the latter case, care was assumed to be primarily differentiated according to viral load level. The maximum intervention cost required to be cost effective was calculated based on a cost effectiveness threshold of $500 per DALY averted. Findings In the absence of viral load monitoring, an adherence monitoring-based intervention which results in a durable 6% increase in the proportion of ART experienced people with viral load < 1000 cps/mL was cost effective if it cost up to $50 per person-year on ART, mainly driven by the cost savings of differentiation of care. In the presence of viral load monitoring availability, an intervention with a similar effect on viral load suppression was cost-effective when costing $23-$32 per year, depending on whether the adherence intervention is used to reduce the level of need for viral load measurement. Conclusion The cost thresholds identified suggest that there is clear scope for adherence monitoring-based interventions to provide net population health gain, with potential cost-effective use in situations where viral load monitoring is or is not available. Our results guide the implementation of future adherence monitoring interventions found in randomized trials to have health benefit. PMID:27977702

The effect of patient-provider communication on medication adherence in hypertensive black patients: does race concordance matter?

PubMed

Schoenthaler, Antoinette; Allegrante, John P; Chaplin, William; Ogedegbe, Gbenga

2012-06-01

Despite evidence of a positive effect of collaborative patient-provider communication on patient outcomes, our understanding of this relationship is unclear. The purpose of this paper is to determine whether racial composition of the relationship modified the association between ratings of provider communication and medication adherence. Effect modification of the communication-adherence association, by racial composition of the relationship, was evaluated using general linear mixed models while adjusting for selected covariates. Three hundred ninety patients were in race-concordant (black patient, black provider) relationships, while 207 were in race-discordant (black patient, white provider) relationships. The communication-adherence association was significantly modified in race-discordant relationships (p = 0.04). Communication rated as more collaborative in race-discordant relationships was associated with better adherence, while communication rated as less collaborative was associated with poor adherence. There was no significant association between adherence and communication in race-concordant relationships (p = 0.24). Collaborative patient-provider communication may play an influential role in black patients' adherence behaviors when receiving care from white providers.

Individual Differences and Day-to-Day Fluctuations in Perceived Self-Regulation Associated With Daily Adherence in Late Adolescents With Type 1 Diabetes

PubMed Central

Wiebe, Deborah J.; Suchy, Yana; Hughes, Amy E.; Anderson, Jessica H.; Godbey, Elida I.; Butner, Jonathan; Tucker, Christy; Franchow, Emilie I.; Pihlaskari, Andrea K.; King, Pamela S.; Murray, Mary A.; White, Perrin C.

2014-01-01

Objective To examine whether individual differences and intraindividual (within-person day-to-day) fluctuations in late adolescents’ self-regulation were associated with daily adherence to the type 1 diabetes regimen. Methods 110 school seniors (M age = 17.78 years) and their mothers assessed adolescents’ skills underlying self-regulation (executive function, attention, self-control, behavioral inhibition and activation, emotion regulation) and adherence, with glycosylated hemoglobin from medical records. Teens completed daily diaries reporting self-regulation failures surrounding monitoring blood glucose, adherence, and number of blood glucose checks each day for 14 days. Results Hierarchical Linear Models indicated that better daily adherence was associated with teen and mother reports of better self-regulation skills and teens’ reports of fewer daily self-regulation failures. Daily adherence was unrelated to temperamental differences in behavioral inhibition and activation. Conclusions Results indicate that both individual and intraindividual differences in self-regulation contribute to daily adherence highlighting the importance of daily self-regulatory challenges to adherence. PMID:25064802