bluuebunny/crossref_metadata_2025_split huggingface dataset:
Immortal time bias in observational studies of drug effects
Authors: Suissa Samy 
Published: January 2007

AbstractPurposeRecent observational studies suggest that various drugs are remarkably effective at reducing morbidity and mortality. These cohort studies used a flawed approach to design and data analysis which can lead to immortal time bias. We describe the bias from 20 of these studies and illustrate it by showing that unrelated drugs can be made to appear effective at treating cardiovascular disease (CVD).MethodsThe illustration used a cohort of 3315 patients, with chronic obstructive pulmonary disease (COPD), identified from the Saskatchewan Health databases, hospitalised for CVD and followed for up to a year. We used the biased approach to assess the effect of two medications, namely gastrointestinal drugs (GID) and inhaled beta‐agonists (IBA), both unknown to be effective in CVD, on the risk of all‐cause mortality. We also estimated these effects using the proper person‐time approach.ResultsUsing the inappropriate approach, the rates ratios of all‐cause death were 0.73 (95%CI: 0.57–0.93), with IBA and 0.78 (95%CI: 0.61–0.99), with GID. These rate ratios became 0.98 (95%CI: 0.77–1.25) and 0.94 (95%CI: 0.73–1.20), respectively, with the proper person‐time analysis.ConclusionsSeveral recent observational studies used a flawed approach to design and data analysis, leading to immortal time bias, which can generate an illusion of treatment effectiveness. Observational studies, with surprising beneficial drug effects should be re‐assessed to account for this source of bias. Copyright © 2007 John Wiley & Sons, Ltd.
Videoconferencing for delivery of breast cancer support groups to women living in rural communities: a pilot study
Authors: Collie Kate , Kreshka Mary Anne , Ferrier Susan , Parsons Rebecca , Graddy Kathy , Avram Speranza , Mannell Patty , Chen Xin‐Hua , Perkins James , Koopman Cheryl 
Published: January 2007

AbstractWomen with breast cancer in rural areas are likely to exhaust their usual sources of psychosocial support while still facing challenges posed by breast cancer, but are unlikely to have access to professionally led support groups. In this community‐based project, we assessed the feasibility and acceptability of providing support groups to women with breast cancer in a large rural area using videoconferencing and a workbook journal, and we assessed the intervention's potential to reduce distress and increase emotional expression and self‐efficacy for coping with cancer. Twenty‐seven women in the Intermountain Region of northeastern California participated in eight‐session support groups led by an oncology social worker by going to nearby videoconferencing sites. Feasibility and acceptability were demonstrated. Older as well as younger women were comfortable using videoconferencing and said the groups were valuable because they promoted information sharing and emotional bonds with other women with breast cancer. They emphasized the importance of a professional facilitator and identified advantages of using videoconferencing for support groups. Pretest and posttest comparisons showed significant decreases in depression and posttraumatic stress disorder symptoms. The results suggest that the intervention has the potential to provide a valuable service that is not readily available in rural communities. Copyright © 2007 John Wiley & Sons, Ltd.
Inhibition of the epidermal growth factor receptor enhances castration‐induced prostate involution and reduces testosterone‐stimulated prostate growth in adult rats
Authors: Hammarsten Peter , Rudolfsson Stina Häggström , Henriksson Roger , Wikström Pernilla , Bergh Anders 
Published: January 2007

AbstractBACKGROUNDThe epidermal growth factor receptor (EGFR) mediates regulatory signals in the normal prostate, but the functional importance of this is unclear.METHODSAdult male rats were castrated, or castrated + treated with gefitinib (Iressa®, ZD1839), an EGFR tyrosine kinase inhibitor, for 3 days. Seven‐day castrated rats were treated with testosterone, or testosterone + gefitinib, for 3 days.RESULTSBoth castration alone and testosterone treatment in castrated animals increased the mRNA and protein levels of EGFR and phospho‐EGFR in the ventral prostate. Inhibition of EGFR during castration and during testosterone‐stimulated prostate growth resulted in a decrease in total epithelial weight, epithelial cell proliferation, endothelial cell proliferation, and increased epithelial cell apoptosis.CONCLUSIONSThis study suggests that increased EGFR signaling during castration mediates stimulatory effects balancing castration‐induced prostate regression, and that EGFR signaling is a necessary component in testosterone‐stimulated prostate growth. Prostate 67: 573–581, 2007. © 2007 Wiley‐Liss, Inc.
EZH2 promotes proliferation and invasiveness of prostate cancer cells
Authors: Bryant R.J. , Cross N.A. , Eaton C.L. , Hamdy F.C. , Cunliffe V.T. 
Published: January 2007

AbstractBACKGROUNDThe transcriptional repressor EZH2 is implicated in control of cell proliferation in embryonic, immortalized and transformed cells. EZH2 expression in prostate cancer correlates with progression to hormone‐refractory and metastatic disease, but it is unknown whether EZH2 plays a specific role in the acquisition of an advanced prostate cancer phenotype.METHODSUsing siRNA knockdown, we investigated the role of EZH2 in maintenance of prostate cancer cell proliferation and invasiveness. Using LNCaP cells with inducible EZH2 overexpression, we investigated whether EZH2 upregulation promotes an aggressive phenotype.RESULTSKnockdown of endogenous EZH2 reduced proliferation of androgen‐responsive and androgen‐independent prostate cancer cells. EZH2 knockdown also inhibited prostate cancer cell invasion. However, overexpression of EZH2 in androgen‐responsive cancer cells did not appreciably affect either proliferation or invasiveness.CONCLUSIONSEZH2 promotes proliferation and invasion of prostate cancer cells, which can account for the correlation between EZH2 expression levels and an adverse prostate cancer prognosis. Prostate 67: 547–556, 2007. © 2007 Wiley‐Liss, Inc.
Effects of cushioning materials on the firmness of Huanghua pears (Pyrus pyrifolia Nakai cv. Huanghua) during distribution and storage
Authors: Zhou Ran , Su Shuqiang , Li Yunfei 
Published: January 2007

AbstractThe type and quality of cushioning materials could significantly affect the vibration intensity and physical quality of fruits during transport. In the current paper, we evaluated the different cushioning materials (paper‐wrap materials, foam‐net packages) for their protective effect on the vibration levels, number of bruises and mechanical damage to Huanghua pears (Pyrus pyrifolia Nakai cv. Huanghua) during transport. Changes in pear firmness, hydrolase activity and cell wall constituents were examined in fruits stored for up to 36 days after transport. Our data suggested that the choice of cushioning material significantly reduced the vibration intensity in transit, affecting the physical quality of fruits and their subsequent commercialization, and that foam‐net packages provided a greater protective effect than paper‐wrap packages. Copyright © 2007 John Wiley & Sons, Ltd.
An empirical Bayesian based approach to delay time inspection model parameters estimation using both subjective and objective data
Authors: Wang W. , Jia X. 
Published: January 2007

AbstractThis paper presents a model on the estimation of delay time inspection model parameters using both subjective and objective data. Delay time based inspection modelling has been increasingly reported in the literature. This has primarily concerned the modelling of inspection intervals, while estimating model parameters is an important task. When either subjective data such as expert judgements or objective data of failure and maintenance interventions are available, approaches to estimate the parameters associated in the delay time inspection model are available to each of the data types. If, however, we have subjective data in the first instance and then objective data become available later, a method using both available information sources is required. This paper reports on a new development of such an approach using a standard hierarchical Bayesian method. The approach starts with subjective data first, and then updates the estimates when objective data become available. The initial estimates are made using the empirical Bayesian method matching with few subjective summary statistics provided by the experts, which differs from previously reported subjective approaches in delay time modelling. Then the updating mechanism enters the process, which requires a repeated evaluation of the likelihood function. Examples based on real and simulated data are presented and findings are discussed. Copyright © 2007 John Wiley & Sons, Ltd.
An optimal burn‐in preventive‐replacement model associated with a mixture distribution
Authors: Jiang R. , Jardine A. K. S. 
Published: January 2007

AbstractA mixture arises in a number of situations. A typical situation is that a population is heterogeneous and consists of several sub‐populations, which represent mutually exclusive failure modes (usually early failures where the mean time to failure (MTTF) is ‘short’ and wear‐out failures where the MTTF is ‘long’ and the hazard rate is increasing). When the time to failure of an item follows a mixture distribution, it is difficult to determine an appropriate operational or/and maintenance policy to reduce the early‐phase failures and field operational cost. This paper examines the effectiveness of jointly applying a burn‐in procedure and preventive replacement policy to such items, and discusses implementation‐related issues associated with the combined policy. A numerical example is also included. Copyright © 2007 John Wiley & Sons, Ltd.
The Carroll–Hung method for component reliability mapping in aircraft maintenance
Authors: Leung Tim , Carroll Tom , Hung May , Tsang Albert , Chung Walter 
Published: January 2007

AbstractMean time between unscheduled removal (MTBUR) measurement is a baseline technique for condition monitoring (CM) in aircraft reliability programmes. Many airlines, component suppliers and airframe manufacturers apply MTBUR analysis because of its simplicity and industry‐wide acceptance for contractual, performance and technical evaluation purposes. Owing to its aggregated nature, MTBUR alone has little to offer for showing the significant changes within a repairable component population. This paper introduces the Carroll–Hung (CH) method, an innovative approach for bridging the industrial practice of CM alerts and the process of identifying candidates for reliability improvement. Through systematic mapping of modulated time‐to‐failure patterns onto finger‐print charts, trained engineers are able to scrutinize life characteristics and then detect inherent issues by making reference to a CH pattern guidebook. Applications at two airlines have proved the method to be simple and effective because the CH algorithm and its unique failure pattern examination technique involve aircraft system knowledge and logistics factors in developing component improvement plans. Possible refinement of the CH methodology using a non‐parametric approach and pattern recognition is planned for future research. Copyright © 2007 John Wiley & Sons, Ltd.
Process and equipment monitoring methodologies applied to sensor calibration monitoring
Authors: Hines J. Wesley , Garvey Dustin 
Published: January 2007

AbstractTraditionally, the calibration of safety critical nuclear instrumentation has been performed at each refueling cycle. However, many nuclear plants have moved toward condition‐directed rather than time‐directed calibration. This condition‐directed calibration is accomplished through the use of on‐line monitoring. On‐line monitoring (OLM) uses an autoassociative empirical modeling architecture to assess instrument channel performance. An autoassociative architecture predicts a group of correct sensor values when supplied a group of sensor values that is usually corrupted with process and instrument noise, and could also contain faults such as sensor drift or complete failure. The Process and Equipment Monitoring (PEM) Toolbox, which was developed at The University of Tennessee, is a set of MATLAB based tools, which have been developed to support the design of process and equipment condition monitoring systems. Its purpose is to provide the necessary functionality so that different empirical modeling and uncertainty estimation methods may be investigated and compared. This paper discusses the purpose and architecture of the PEM Toolbox, as well as presenting an example application to power plant sensor calibration monitoring using actual plant data. Copyright © 2007 John Wiley & Sons, Ltd.
Predictive condition‐based maintenance for continuously deteriorating systems
Authors: Lu Susan , Tu Yu‐Chen , Lu Huitian 
Published: January 2007

AbstractThis paper addresses a predictive condition‐based maintenance approach based on monitoring, modeling, and predicting a system's deterioration. The system's deterioration is considered as a stochastic dynamic process with continuous degrading. Structural time series, coupled with state‐space modeling and Kalman filtering methods, is adopted for recursively modeling and forecasting the deterioration state at a future time. The probability of a failure is then predicted based on the forecasted deterioration state and a threshold of a failure. Finally, maintenance decisions are made according to the predicted failure probabilities, associated preventive and corrective maintenance cost, and the profit loss due to system performance deterioration. The approach can be applied on‐line to provide economic and preventive maintenance solutions in order to maximize the profit of the ownership of a system. Copyright © 2007 John Wiley & Sons, Ltd.
Desorption electrospray ionisation mass spectrometric analysis of chemical warfare agents from solid‐phase microextraction fibers
Authors: D'Agostino Paul A. , Chenier Claude L. , Hancock James R. , Lepage Carmela R. Jackson 
Published: January 2007

AbstractDesorption electrospray ionisation mass spectrometry (DESI‐MS) was recently reported for the direct analysis of sample media without the need for additional sample handling. During the present study, direct analysis of solid‐phase microextraction (SPME) fibers by DESI‐MS/MS was evaluated with indoor office media that might be collected during a forensic investigation, including wall surfaces, office fabrics, paper products and Dacron swabs used for liquid sampling. Media spiked at the µg/g level with purified chemical warfare agents and a complex munitions grade sample of tabun, to simulate the quality of chemical warfare agent that might be used for terrorist purposes, were successfully analysed by DESI‐MS/MS. Sulfur mustard, a compound that has not been successfully analysed by electrospray mass spectrometry in the past, was also sampled using a SPME fiber and analysed for the first time by DESI‐MS/MS. Finally, the overall analytical approach involving SPME headspace sampling and DESI‐MS analysis was evaluated during a scenario‐based training live agent exercise. A sarin sample collected by the military was analysed and confirmed by DESI‐MS in a mobile laboratory under realistic field conditions. Copyright © 2007 Crown in the right of Canada. Published by John Wiley & Sons, Ltd.
Statistical power of multiplicity adjustment strategies for correlated binary endpoints
Authors: Leon Andrew C. , Heo Moonseong , Teres Jedediah J. , Morikawa Toshihiko 
Published: January 2007

AbstractThere are numerous alternatives to the so‐called Bonferroni adjustment to control for familywise Type I error among multiple tests. Yet, for the most part, these approaches disregard the correlation among endpoints. This can prove to be a conservative hypothesis testing strategy if the null hypothesis is false. The James procedure was proposed to account for the correlation structure among multiple continuous endpoints. Here, a simulation study evaluates the statistical power of the Hochberg and James adjustment strategies relative to that of the Bonferroni approach when used for multiple correlated binary variables. The simulations demonstrate that relative to the Bonferroni approach, neither alternative sacrifices power. The Hochberg approach has more statistical power for ρ⩽0.50; whereas the James procedure provides more statistical power with higher ρ, the common correlation among the multiple outcomes. A study of gender differences in New York City homicides is used to illustrate the approaches. Copyright © 2007 John Wiley & Sons, Ltd.
DIFFUSIVE TRANSPORT OF PARTIALLY QUANTIZED PARTICLES: EXISTENCE, UNIQUENESS AND LONG-TIME BEHAVIOUR
Authors: Ben Abdallah N. , Méhats F. , Vauchelet N. 
Published: January 2007

AbstractA self-consistent model for charged particles, accounting for quantum confinement, diffusive transport and electrostatic interaction is considered. The electrostatic potential is a solution of a three-dimensional Poisson equation with the particle density as the source term. This density is the product of a two-dimensional surface density and that of a one-dimensional mixed quantum state. The surface density is the solution of a drift–diffusion equation with an effective surface potential deduced from the fully three-dimensional one and which involves the diagonalization of a one-dimensional Schrödinger operator. The overall problem is viewed as a two-dimensional drift–diffusion equation coupled to a Schrödinger–Poisson system. The latter is proven to be well posed by a convex minimization technique. A relative entropy and an a priori $L^2$ estimate provide sufficient bounds to prove existence and uniqueness of a global-in-time solution. In the case of thermodynamic equilibrium boundary data, a unique stationary solution is proven to exist. The relative entropy allows us to prove the convergence of the transient solution towards it as time grows to infinity. Finally, the low-order approximation of the relative entropy is used to prove that this convergence is exponential in time.
THE FACTORIZABLE BRAID MONOID
Authors: East James 
Published: January 2007

AbstractIn this paper we study the factorizable braid monoid (also known as the merge-and-part braid monoid) introduced by Easdown, East and FitzGerald in 2004. We find several presentations of this monoid, and uncover an interesting connection with the singular braid monoid. This leads to the definition of the flexible singular braid monoid, which consists of ‘flexible-vertex-isotopy’ classes of singular braids. We conclude by defining and studying the pure factorizable braid monoid, the maximal subgroups of which are (isomorphic to) quotients of the pure braid group.
NONLINEAR NON-LOCAL BOUNDARY-VALUE PROBLEMS AND PERTURBED HAMMERSTEIN INTEGRAL EQUATIONS
Authors: Infante Gennaro , Webb J. R. L. 
Published: January 2007

AbstractMotivated by some non-local boundary-value problems (BVPs) that arise in heat-flow problems, we establish new results for the existence of non-zero solutions of integral equations of the form$$ u(t)=\gamma(t)\alpha[u]+\int_{G}k(t,s)f(s,u(s))\,\mathrm{d}s, $$where $G$ is a compact set in $\mathbb{R}^{n}$. Here $\alpha[u]$ is a positive functional and $f$ is positive, while $k$ and $\gamma$ may change sign, so positive solutions need not exist. We prove the existence of multiple non-zero solutions of the BVPs under suitable conditions. We show that solutions of the BVPs lose positivity as a parameter decreases. For a certain parameter range not all solutions can be positive, but for one of the boundary conditions we consider we show that there are positive solutions for certain types of nonlinearity. We also prove a uniqueness result.
THE BOUSFIELD–KAN SPECTRAL SEQUENCE FOR MORAVA $K$-THEORY
Authors: La Luz José 
Published: January 2007

AbstractWe construct a spectral sequence converging to the $E_{2}$-term of the Bousfield–Kan spectral sequence (BKSS) for a wide variety of homology theories. Using this, the $E_{2}$-term of the BKSS based on $K(1)$-theory for the odd spheres is computed and the unstable $K(1)$-completion is computed.
Different surgical treatments for nasal septal perforation and their outcomes
Authors: Goh A Y , Hussain S S M 
Published: January 2007

Objective: To critically evaluate the literature on surgical treatment options for nasal septal perforations and to analyse the outcomes of these treatment options.Design: A systematic review of studies of nasal septal perforation closure using surgical intervention, published from January 1975 to March 2006.Data sources: Forty-nine papers were identified from electronic databases (all Evidence Based Medicine reviews (Cochrane Database of Systematic Reviews, American College of Physicians Journal Club, Database of Abstracts of Reviews of Effectiveness and Cochrane Controlled Trials Register), EMBASE, Ovid (Medline) and British Medical Journal publications) and from a hand search of the reference lists of retrieved papers. Textbooks pertinent to the subject were referred to for background reading. Twenty-three studies met the inclusion criteria.Main outcome measure: Effectiveness of the surgical intervention to completely close the perforation.Results: Five studies examined the sole use of intranasal mucosal flaps to close the perforation, i.e. inferior turbinate flaps, quadrangular cartilage flap and mucoperiosteal flap. Eighteen studies reported the use of a combination of intranasal mucosal flap and interposition graft. Graft materials included temporalis fascia, mastoid periosteum, nasal septal material, acellular human dermal graft, conchal cartilage and porcine small intestine mucosa. Studies utilising interposition grafts generally produced higher closure rates. The surgical approaches documented include closed endonasal, unilateral hemitransfixion, external rhinoplasty and midfacial degloving techniques. A range of surgical treatment methods was reported in the literature, but some papers were excluded from this review as they did not meet the inclusion criteria. It was difficult to infer the true effectiveness of each study as the subject numbers were small, patient selection criteria were often unspecified and the follow-up period was brief. However, factors leading to an increased chance of success were identified.Conclusion: The review found an extensive range of surgical treatment techniques, but reported results were rarely statistically significant. It is difficult to be categorical about the effectiveness of a surgical treatment method; nonetheless, each technique has its own advantages and drawbacks.