bluuebunny/crossref_metadata_2025 huggingface dataset:
Incidence of Newly Detected Atrial Arrhythmias via Implantable Devices in Patients With a History of Thromboembolic Events
Authors: Ziegler Paul D. , Glotzer Taya V. , Daoud Emile G. , Wyse D. George , Singer Daniel E. , Ezekowitz Michael D. , Koehler Jodi L. , Hilker Christopher E.
Published: January 2010

Background and Purpose—

Evidence of atrial tachycardia/atrial fibrillation (AT/AF) is often sought in patients with ischemic stroke or transient ischemic attack. We studied patients with previous thromboembolic events (TE) who were implanted with devices capable of continuous arrhythmia monitoring to comprehensively quantify the incidence and duration of newly detected AT/AF.

Methods—

This study represents a subgroup analysis of the TRENDS trial, which included patients with clinical indications for pacemakers or defibrillators and ≥1 stroke risk factors (heart failure, hypertension, age 65 or older, diabetes, or previous TE). A history of AF was not required. All implanted devices were capable of continuously monitoring the cumulative time spent in AT/AF each day. This analysis focuses primarily on the incidence and duration of newly detected AT/AF (defined as ≥5 minutes of AT/AF on any day) in patients with previous TE, no documented history of AF, and no warfarin or antiarrhythmic drug use.

Results—

A total of 319 patients had a history of TE and ≥1 day of device data. Patients with a documented history of AF (n=80), warfarin use (n=56), or antiarrhythmic drug use (n=20) were excluded from analysis. Of the remaining 163 patients, newly detected AT/AF was identified via the device in 45 patients (28%) over a mean follow-up of 1.1±0.7 years. AT/AF recurred infrequently, with only 12 patients experiencing AT/AF on >10% of follow-up days.

Conclusion—

Newly detected episodes of AT/AF were found via continuous monitoring in 28% of patients with previous TE. Most episodes would not have been detected by standard intermittent monitoring techniques.
Single-Institutional 22 Years Experience on Cardiac Myxomas
Authors: Cetin Gurkan , Gursoy Mete , Ugurlucan Murat , Uzunhasan Isil , Hatemi Ali Can , Tireli Emin , Kucukoglu Serdar , Kansiz Erhan
Published: December 2009

Myxomas are the most common benign tumors of the heart. This study presents single-institutional 22 years experience on cardiac myxomas. The records of 9756 consecutive cases of open heart surgery between 1985 and 2007 revealed 0.23% myxoma. Age ranged between 12 and 77 years and male to female ratio was 7:17. Myxomas originated from the left atrium (15 patients), mitral valve (3 patients), right atrium (2 patients), right atrium and right ventricle (2 patients), right ventricle (1 patient), and left ventricle (1 patient). Three patients were operated for multiple myxomas. Myxomas were resected through right atriotomy, right atriotomy and pulmonary arteriotomy, left atriotomy, biatrial approach, or left ventriculotomy depending on the tumor location. Mean follow-up time was 11.5 years. Mortality occurred in 6 patients (1 early, 5 late deaths). No myxoma recurrence was detected. Myxomas should be resected leaving no remnant mass, without delay when they are diagnosed.
Modeling Quantitative Literacy
Authors: Wilkins Jesse L. M.
Published: December 2009

Quantitative literacy is a habit of mind that is characterized by the interrelationship among a person’s everyday understanding of mathematics, his or her beliefs about mathematics, and his or her disposition toward mathematics. To assess quantitative literacy, it is important to devise measurement tools that provide valid and reliable information about a person’s quantitative literacy. In this study, exploratory factor analysis and confirmatory factor analysis were used to build and evaluate a measurement model of quantitative literacy. Data from the Second International Mathematics Study (SIMS) were used to create calibration ( N = 1,429) and validation samples ( N = 1,429) of high school students for testing an initial model and cross-validation. An additional sample of high school students ( N = 1,429) collected from the midwestern part of the United States was used in a replication study. In each stage, a hierarchical three-factor model was compared with two alternative rival models: a one-factor model and a hierarchical two-factor model. The results of the analyses supported the structure of the hierarchical three-factor model. Implications and limitations associated with the findings from the study are discussed.
A Test and Cross-Validation of the Revised Two-Factor Study Process Questionnaire Factor Structure Among Western University Students
Authors: Immekus Jason C. , Imbrie P.K.
Published: January 2010

The Revised Two-Factor Study Process Questionnaire (R-SPQ-2F) is a measure of university students’ approach to learning. Original evaluation of the scale’s psychometric properties was based on a sample of Hong Kong university students’ scores. The purpose of this study was to test and cross-validate the R-SPQ-2F factor structure, based on separate cohort data (Cohort 1: n = 1,490; Cohort 2: n = 1,533), among students attending a university in the United States. Factor analytic results did not support the scale’s original factor structure, instead suggesting an alternative four-factor model of the scale data. In the cross-validation study, multisample confirmatory factor analysis results indicated that the scale’s measurement model parameters (e.g., factor loadings) were invariant across independent samples. Despite support for the scale’s respecified factor structure for Western university students, continued research is recommended to improve the scale’s psychometric properties. Implications for test score use and interpretation are discussed.
Coworker Informal Work Accommodations to Family: Scale Development and Validation
Authors: Mesmer-Magnus Jessica , Murase Toshio , DeChurch Leslie A. , Jiménez Miliani
Published: December 2009

Drawing on research regarding the utility of coworker support in mitigating work/ family conflict, the authors developed a scale to measure Coworker-enacted Informal Work Accommodations to Family (C-IWAF). C-IWAF differs from coworker support in that it describes actual behaviors coworkers engage in to help one another deal with incompatible work and family demands. Results based on a sample of 390 working caregivers provide support for the independence of C-IWAF from other forms of coworker support. Analyses of the factor structure obtained for this instrument indicate that C-IWAF is composed of six unique factors: child care assistance, facilitating telework, continuing work modification, short-term work modification, helping behavior, and deviating behavior. Implications of these results for research and practice are discussed.
A Comparison of Approaches for Improving the Reliability of Objective Level Scores
Authors: Skorupski William P. , Carvajal Jorge
Published: December 2009

This study is an evaluation of the psychometric issues associated with estimating objective level scores, often referred to as ‘‘subscores.’’ The article begins by introducing the concepts of reliability and validity for subscores from statewide achievement tests. These issues are discussed with reference to popular scaling techniques, classical test theory, and item response theory. Methods for increasing the reliability of subscore estimates that have been suggested in literature are then reviewed. Based on this review, an empirical study comparing some of the more promising procedures was conducted. Test score data from a large statewide testing program were analyzed in this study. The comparison of subscore augmentation approaches found that generally all methods were very successful in dramatically increasing the reliability of subscore estimates. However, this increase was accompanied by near-perfect correlations among the subscore estimates. This finding called into question the validity of the resultant subscores, and therefore the usefulness of the subscore augmentation process. Implications for practice are discussed.
Factor Loading Estimation Error and Stability Using Exploratory Factor Analysis
Authors: Sass Daniel A.
Published: January 2010

Exploratory factor analysis (EFA) is commonly employed to evaluate the factor structure of measures with dichotomously scored items. Generally, only the estimated factor loadings are provided with no reference to significance tests, confidence intervals, and/or estimated factor loading standard errors. This simulation study assessed factor loading estimation error under several experimental conditions and whether hypothesis testing and/or confidence intervals should be employed. Results revealed that the promax rotation performed well with small interfactor correlations and simple structure data, whereas varimax only performed well with orthogonal factors. Neither rotation method performed well with larger interfactor correlations or approximate simple structure data. An explanation of these results is provided.
Strategies Used by Intellectually Gifted Students to Cope With Stress During Their Participation in a High School International Baccalaureate Program
Authors: Shaunessy Elizabeth , Suldo Shannon M.
Published: December 2009

Individuals respond to threats to affiliation and achievement needs through drawing on a repertoire of coping strategies specific to a given situation. Gifted adolescents in college-preparatory high school programs may be faced with novel stressors, and may have unique coping strategies to manage these challenges. The current study considers responses to surveys of stress and coping as well as focus group interviews of gifted and high-achieving students enrolled in an academically intense curriculum, the International Baccalaureate (IB) Diploma Program. Findings of this secondary analysis of archival data sets indicate gifted students experience levels of stress similar to their IB classmates not identified as gifted. Additionally, gifted students were similar to IB peers not identified as gifted with respect to how they cope with school; likenesses included positive reframing, time and task management, avoiding tasks, and seeking social support. However, gifted IB students differed from IB classmates with respect to anger coping, humor, and problem-solving approaches.

Putting the Research to Use

With the growing interest of International Baccalaureate Programs throughout the United States, educational personnel, researchers, and administrators are considering the social-emotional needs of gifted and high-ability students served in these challenging academic programs. Understanding the needs of this unique population of students is critical to supporting the cognitive and affective growth of IB students, and this study provides a glimpse into the thoughts of IB learners with respect to their stress and coping.The findings of this study suggests that gifted students in IB and their IB peers experience similar stressors and coping responses, though some differences in anger coping, humor, and problem solving were unique among gifted IB students in this sample.
Effect of Gamma Irradiation on Ultimate Tensile Strength of Enamel and Dentin
Authors: Soares C.J. , Castro C.G. , Neiva N.A. , Soares P.V. , Santos-Filho P.C.F. , Naves L.Z. , Pereira P.N.R.
Published: December 2009

The effect of gamma irradiation therapy on the ultimate tensile strength (UTS) of enamel and dentin in relation to prism orientation, dentin tubule orientation, and location is unknown. It was hypothesized that tubule and prism orientation, location, and irradiation have an effect on the UTS of dental structures. Forty human third molars were used, half of which were subjected to 60 Gy of gamma irradiation, in daily increments of 2 Gy. The specimens were evaluated by microtensile testing. Results showed that irradiation treatment significantly decreased the UTS of coronal and radicular dentin and of enamel, regardless of tubule or prism orientation. With or without irradiation, enamel was significantly stronger when tested parallel to its prismatic orientation. Coronal and radicular dentin of non-irradiated specimens presented significantly higher UTS when tested perpendicularly to tubule orientation. However, when the teeth were irradiated, the influence of tubule orientation disappeared, demonstrating that irradiation is more harmful to organic components.
Khat Alters the Phenotype of in vitro-reconstructed Human Oral Mucosa
Authors: Lukandu O.M. , Neppelberg E. , Vintermyr O.K. , Johannessen A.C. , Costea D.E.
Published: January 2010

Khat-chewing has been associated with oral lesions including oral cancer, but the mechanisms leading to their development are not known. We hypothesized that khat interferes with the physiological processes of the oral mucosa, such as cell proliferation and differentiation, and aimed at investigating the effects of khat exposure on in vitro-reconstructed human normal buccal mucosa. Khat decreased cell proliferation, epithelial thickness, and cytokeratin 13 expression, while inducing premature expression of p21Waf1/Cip1, transglutaminases, involucrin, and filaggrin. This suggests that khat is able to induce abnormal differentiation of the buccal epithelium. Khat-induced alterations were accompanied by increased levels of p38 and were reversed by p38 inhibition, pointing to p38 as the key player in this process. The morphological changes described herein mirror the in vivo changes previously described in khat users, and demonstrate for the first time that khat induces pathological alterations in human buccal mucosa, providing evidence that raises concerns about the effects of khat use on oral health.
Identification of a Suppressor Element in the Amelogenin Promoter
Authors: Xu L. , Matsumoto A. , Sasaki A. , Harada H. , Taniguchi A.
Published: January 2010

Amelogenin expression is regulated in a cell-type- specific manner. Investigators have previously identified an enhancer element by using the 5′ flanking sequence of the amelogenin promoter. However, the cell-type-specific regulation of the amelogenin gene remains poorly understood. In some genes, the first intron regulates tissue-specific expression. We hypothesized that intron 1 is important for the cell-type-specific regulation of amelogenin expression. We identified a suppressor element between −74 and −464. We also found enhancer activity in intron 1. Additionally, we found that the suppressor element in the promoter region suppressed intron 1 enhancer activity. The suppressor and the enhancers acted in an ameloblast-like cell line, but not in HeLa cells. Mutation of the Oct-1 binding sites reversed the suppressor activity, suggesting that Oct-1 sites are essential for suppression. These results suggest that Oct-1 and intron 1 may contribute to cell-type-specific amelogenin expression.
Formation of the Tooth-Bone Interface
Authors: Fleischmannova J. , Matalova E. , Sharpe P.T. , Misek I. , Radlanski R.J.
Published: December 2009

Not only are teeth essential for mastication, but also missing teeth are considered a social handicap due to speech and aesthetic problems, with a resulting high impact on emotional well-being. Several treatment procedures are currently available for tooth replacement with mostly inert prosthetic materials and implants. Natural tooth substitution based on copying the developmental process of tooth formation is particularly challenging and creates a rapidly developing area of molecular dentistry. In any approach, functional interactions among the tooth, the surrounding bone, and the periodontium must be established. Therefore, recent research in craniofacial genetics searches for mechanisms responsible for correct cell and tissue interactions, not only within a specific structure, but also in the context of supporting structures. A tooth crown that is not functionally anchored to roots and bone is useless. This review aims to summarize the developmental and tissue homeostatic aspects of the tooth-bone interface, from the initial patterning toward tooth eruption and lifelong interactions between the tooth and its surrounding alveolar bone.
Alteration of PTGS2 Promoter Methylation in Chronic Periodontitis
Authors: Zhang S. , Barros S.P. , Niculescu M.D. , Moretti A.J. , Preisser J.S. , Offenbacher S.
Published: December 2009

Levels of prostaglandin E2 and the prostaglandin-endoperoxide synthase-2 ( PTGS2, or COX-2) increase in actively progressing periodontal lesions, but decrease in chronic disease. We hypothesized that chronic inflammation is associated with altered DNA methylation levels within the PTGS2 promoter, with effects on COX-2 mRNA expression. PTGS2 promoter methylation levels from periodontally inflamed gingival biopsies showed a 5.06-fold increase as compared with non-inflamed samples (p = 0.03), and the odds of methylation in a CpG site in the inflamed gingival group is 4.46 times higher than in the same site in the non-inflamed group (p = 0.016). The level of methylation at −458 bp was inversely associated with transcriptional levels of PTGS2 (RT-PCR) (p = 0.01). Analysis of the data suggests that, in chronically inflamed tissues, there is a hypermethylation pattern of the PTGS2 promoter in association with a lower level of PTGS2 transcription, consistent with a dampening of COX-2 expression in chronic periodontitis. These findings suggest that the chronic persistence of the biofilm and inflammation may be associated with epigenetic changes in local tissues at the biofilm-gingival interface.
Finite Element Analysis of a TMJ Implant
Authors: Kashi A. , Chowdhury A. Roy , Saha S.
Published: December 2009

To determine the causes of failure of an artificial temporomandibular joint implant, one must study the magnitude and location of the maximum stresses under physiological loading. In this study, we analyzed the stresses in a commercially available TMJ implant, the bone ( i.e., mandible), and the bone-implant interface using a finite element software package. Both titanium and Co-Cr-Mo/Vitallium metals as well as bones with various degrees of osteoporosis were studied. The results of the analysis showed that the maximum stresses occurred at the location of the first screw hole (closest to the condyle) of the implant. In addition, the highest microstrains were observed in the bone adjacent to the first screw hole. The results of our study have potential clinical benefit in terms of improved implant design and hence better performance.
Fundamental Flaws of the DSM: Re-Envisioning Diagnosis
Authors: Bradford G. Kenneth
Published: January 2010

The Diagnostic and Statistical Manual (DSM) of mental disorders is evaluated according to the empirical scientific criteria of validity and reliability, and it is found to be fundamentally flawed on both counts. Additionally, any diagnostic approach based on the objectivizing principles of empirical science is found to be both ontologically and epistemologically unable to account for the complexity of human subjectivity/intersubjectivity. A revisioning of psychological diagnosis according to specifically human scientific criteria is called for; and an outline of criteria to serve as fundamental guidelines for the development of phenomenological and holistic approaches to diagnosis is presented.
Does “Psychological Dysfunction” Mean Anything? A Critical Essay on Pathology Versus Agency
Authors: Jacobs David H. , Cohen David
Published: January 2010

Any effort to discuss or study psychopathology (by any name) must decide how to distinguish between psychopathology and narratively comprehensible reactions to adverse circumstances of life. A pathology framework, which views the distressed individual as acted on by impersonal forces, is incompatible with an agential framework, which views the individual as the protagonist in a unique story. Although the Diagnostic and Statistical Manual of Mental Disorders ( DSM) recognizes this issue, it addresses it by postulating that “primary mental disorder” results from a “psychological dysfunction” and non—culturally sanctioned reactions to life events indicate mental disorder. In this essay, the authors examine whether the concept of “psychological dysfunction” can withstand an analogy to that of biological dysfunction. They also examine the DSM’s view that “culture” has already prepared an official evaluation of any reaction to the vicissitudes of life. They conclude that the DSM has failed to convincingly distinguish between psychopathology and reactions to life’s vicissitudes. They suggest that the DSM’s insistence on separating people’s feelings and actions from their own unique circumstances and context amounts to a moral, not scientific enterprise. The study of how people fare in living should abandon the concept of mental disorder and related terms.
Access to Music Education: Nebraska Band Directors’ Experiences and Attitudes Regarding Students With Physical Disabilities
Authors: Nabb David , Balcetis Emily
Published: December 2009

Students with physical disabilities frequently are excluded from participation in instrumental music programs, yet the obstacles band directors face that preclude integration of these students have not been documented systematically. The primary purpose of this study was to measure Nebraska High School band directors’ concerns regarding the integration of students with physical disabilities into their band programs. Results of a survey of 221 Nebraska high school music programs suggested that awareness of options for ways to include students with physical disabilities, availability of adapted instruments, and the cost of acquiring such instruments are among band directors’ primary concerns. Conclusions drawn from this survey serve as evidence that there is a need for adapted instruments and suggest that integration of students with disabilities and without disabilities in band would provide benefits for all.
Making Sense of Durkheim’s Methodological Prescriptions
Authors: Springer de Freitas Renan
Published: December 2009

In his struggle to constitute sociology as a natural science, Durkheim fought against finalism, Gabriel Tarde’s general project, efforts at theoretical synthesis unconnected to specific empirical problems, and ideological analysis. The article dwells on these four “epistemological battles,” especially on Durkheim’s (unfortunately failed) effort toward purging the social sciences from ideological analysis.
Why Immigration Controls Are Not Coercive: A Reply to Arash Abizadeh
Authors: Miller David
Published: December 2009

Abizadeh has argued that because border controls coerce would-be immigrants and invade their autonomy, they are entitled to participate in the democratic institutions that impose those controls. In reply, the author distinguishes between coercion and prevention, shows that prevention need not undermine autonomy, and concludes that although border controls may restrict freedom, they do not give rise to democratic entitlements.
The Effect of Epoxidized Safflower Oil on the Properties of Polyvinyl Chloride Films
Authors: Sun Thomas , Thom Robyn
Published: December 2009

Polyvinyl chloride (PVC) is among the top three most widely used plastics globally. Di(2-ethylhexyl) phthalate (DEHP) is often added as a plasticizer by up to 40 wt% to impart flexibility. DEHP, a toxin and carcinogen, can leach into the atmosphere to cause environmental contamination. This study investigates the suitability of epoxidized safflower oil, namely Carthamus tinctorius oil (ECTO), as a PVC plasticizer. PVC films with DEHP and ECTO were compared in resilience, elastic modulus, toughness, and glass transition temperature. ECTO films displayed statistically similar physical properties of resilience, elastic modulus, and toughness at up to 30 wt%. ECTO films of 0 to 40 wt% all displayed significantly lower glass transition temperature.
Vision Is Precious
Authors: Jones Hollie L. , Walker Elizabeth A. , Schechter Clyde B. , Blanco Emelinda
Published: January 2010

Purpose

This purpose of this report is to describe a successful telephone intervention to increase the rate of diabetic retinopathy screening, its implementation with English and Spanish speakers, and the characteristics of those who benefited most from the intervention.

Methods

Participants in the telephone group (N = 305) received a tailored intervention from trained health educators who were ethnically diverse and representative of the community. The main outcome for the randomized controlled study was documented receipt of a dilated fundus examination (DFE) within the 6-month study window. Exploratory analyses focused on examining the factors that contribute to receiving a DFE within 6 months for participants in the tailored telephone intervention using Pearson χ2 and logistic regression analysis.

Results

Participants in the telephone intervention who did not receive a DFE had significantly more documented steps in the behavioral process than those who did receive a DFE, and ethnic concordance of the health educator was not significantly associated with a positive outcome in the DFE group. There was a negative association between the time spent building rapport and receipt of DFE. As time spent engaging in educational activities by telephone increased, the likelihood of receiving a DFE increased.

Conclusions

Although the telephone intervention was highly successful compared with the print intervention, these process results demonstrate the difficulties and challenges of conducting a tailored telephone intervention to improve rates of screening in an underserved, diverse urban community.
A Space-Time Approach to Diffusion of Health Service Provision Information
Authors: Casas Irene , Delmelle Eric , Varela Alejandro
Published: December 2009

This article presents a space—time diffusion analysis of health service provision information based on first-time patients of a recently opened hospital located in a disadvantaged neighborhood in Cali, Colombia. It models the patients’ distribution focusing on diffusion using a geographic information system (GIS). The interest in the hospital stems from its location in a very poor and dangerous neighborhood, its portfolio of services, and recent opening. Data used correspond to first-time patient records of all individuals visiting the hospital since its inauguration. Each record contains the profile of the patient, the treatment type, as well as his or her geographic origin. Data are analyzed in space and time to determine whether any patterns exist to suggest a particular flow path or clusters of patients to the hospital. This information helps hospital administrators adapt and propose new policies that can either improve or continue the performance to reach a set goal. The methodology presented can be used by any hospital, institution, or organization that provides a service and whose access can be constrained by exogenous factors.
Identifying the Unauthorized Use of Examination Material
Authors: Wood Timothy J. , St-Onge Christina , Boulais André-Philippe , Blackmore David E. , Maguire Thomas O.
Published: December 2009

Item disclosure is one of the most serious threats to the validity of high stakes examinations, and identifying examinees that may have had unauthorized access to material is an important step in ensuring the integrity of an examination. A procedure was developed to identify examinees that potentially had unauthorized prior access to examination content. A standardized difference score is created by comparing examinee ability estimates for potentially exposed items to ability estimates for unexposed items. Outliers in this distribution are then flagged for further review. The steps associated with this procedure are described and followed by an example of applying the procedure. In addition, the use of this procedure is supported by the results of a simulation that models the use of unauthorized access to examination material.
Techniques to Pass on: Technology and Euthanasia
Authors: Martin Brian
Published: December 2009

Proponents and opponents of euthanasia have argued passionately about whether it should be legalized. In Australia in the mid-1990s, following the world’s first legal euthanasia deaths, Dr. Philip Nitschke initiated a different approach: a search for do-it-yourself technological means of dying with dignity. The Australian government has opposed this effort, especially through heavy censorship. The citizen efforts led by Nitschke have the potential to move the euthanasia issue from a debate about legalization to a struggle over technology.
Measuring Acceptability of Clinical Decision Rules: Validation of the Ottawa Acceptability of Decision Rules Instrument (OADRI) in Four Countries
Authors: Brehaut Jamie C. , Graham Ian D. , Wood Timothy J. , Taljaard Monica , Eagles Debra , Lott Alison , Clement Catherine , Kelly Anne-Maree , Mason Suzanne , Kellerman Arthur , Stiell Ian G.
Published: December 2009

Background. Clinical decision rules can benefit clinicians, patients, and health systems, but they involve considerable up-front development costs and must be acceptable to the target audience. No existing instrument measures the acceptability of a rule. The current study validated such an instrument. Methods. The authors administered the Ottawa Acceptability of Decision Rules Instrument (OADRI) via postal survey to emergency physicians from 4 regions (Australasia, Canada, United Kingdom, and United States), in the context of 2 recently developed rules, the Canadian C-Spine Rule (C-Spine) and the Canadian CT Head Rule (CT-Head). Construct validity of the 12-item instrument was evaluated by hypothesis testing. Results. As predicted by a priori hypotheses, OADRI scores were 1) higher among rule users than nonusers, 2) higher among those using the rule ‘‘all of the time’’ v. ‘‘most of the time’’ v. ‘‘some of the time,’’ and 3) higher among rule nonusers who would consider using a rule v. those who would not. We also examined explicit reasons given by respondents who said they would not use these rules. Items in the OADRI accounted for 85.5% (C- Spine) and 90.2% (CT-Head) of the reasons given for not considering a rule acceptable. Conclusions. The OADRI is a simple, 12-item instrument that evaluates rule acceptability among clinicians. Potential uses include comparing multiple ‘‘protorules’’ during development, examining acceptability of a rule to a new audience prior to implementation, indicating barriers to rule use addressable by knowledge translation interventions, and potentially serving as a proxy measure for future rule use.
Markov Decision Processes: A Tool for Sequential Decision Making under Uncertainty
Authors: Alagoz Oguzhan , Hsu Heather , Schaefer Andrew J. , Roberts Mark S.
Published: January 2010

We provide a tutorial on the construction and evaluation of Markov decision processes (MDPs), which are powerful analytical tools used for sequential decision making under uncertainty that have been widely used in many industrial and manufacturing applications but are underutilized in medical decision making (MDM). We demonstrate the use of an MDP to solve a sequential clinical treatment problem under uncertainty. Markov decision processes generalize standard Markov models in that a decision process is embedded in the model and multiple decisions are made over time. Furthermore, they have significant advantages over standard decision analysis. We compare MDPs to standard Markov-based simulation models by solving the problem of the optimal timing of living-donor liver transplantation using both methods. Both models result in the same optimal transplantation policy and the same total life expectancies for the same patient and living donor. The computation time for solving the MDP model is significantly smaller than that for solving the Markov model. We briefly describe the growing literature of MDPs applied to medical decisions.
Patellar Height and Posterior Tibial Slope after Open- and Closed-Wedge High Tibial Osteotomy
Authors: El-Azab Hosam , Glabgly Parpakorn , Paul Jochen , Imhoff Andreas B. , Hinterwimmer Stefan
Published: January 2010

Background

Valgus high tibial osteotomy (HTO) may be associated with changes in the patellar height and posterior tibial slope.

Hypothesis

Patellar height increases and posterior tibial slope decreases after closed-wedge HTO, whereas patellar height decreases and tibial slope increases after open-wedge osteotomy.

Study Design

Cohort study; Level of evidence, 3.

Methods

Lateral radiographs of 100 knees were assessed for patellar height (PH) (Insall-Salvati index [ISI], Caton-De Champ index [CDI], and Blackburne-Peel index [BPI]) as well as posterior tibial slope. Measurements were done before HTO (50 closed wedge [CW], 50 open wedge [OW]), direct postoperatively, and before removal of the hardware.

Results

In the CW group, all 3 PH indices were increased direct postoperatively and at removal of the hardware, with changes in CDI and BPI being significant (P < .05). The effect size (ES) for the direct postoperative PH increase was medium (ES = 0.48) according to CDI. In the OW group, all 3 indices showed a significant (P < .05) PH decrease direct postoperatively and at hardware removal. The ES for the direct postoperative PH decrease was large according to CDI (ES = 0.92) and BPI (ES = 0.80). There were no significant changes between the 2 follow-up measurements (P > .05) with a small ES each. Posterior tibial slope showed a significant (P < .05) decrease of 3.1° ± 3.4° after CW HTO and a significant (P < .05) increase of 2.1° ± 3.6° after OW HTO direct postoperatively. These changes did not change at the second follow-up. In CW HTO, the correlations between frontal plane correction and PH changes were moderate (CDI: r = .57; BPI: r = .64). In OW HTO, these correlations were weak (CDI: r = .44; BPI: r = .46). According to ISI, there was no correlation (CW: r = .11; OW: r = .16). There was no correlation between PH changes and slope changes (CDI) and no correlation between frontal plane HTO correction and slope changes in both CW and OW HTO.

Conclusion

The results confirm our hypothesis for PH and posterior tibial slope changes after valgus HTO. However, there is no strong correlation between PH changes and the degree of frontal plane HTO correction. The incidence of patella infera increases after OW HTO, whereas the incidence of patella alta increases after CW HTO. Therefore, we recommend performing CW HTO or OW HTO with the tuberosity left at the proximal tibia in cases of patellofemoral complaints or patella infera. Neither technique leads to patellar lowering. It should be borne in mind that PH and posterior tibial slope may have been altered before planning total knee replacement after HTO.
Pelvic Fractures Resulting from Snowboarding
Authors: Ogawa Hiroyasu , Sumi Hiroshi , Sumi Yasuhiko , Shimizu Katsuji
Published: January 2010

Background

Information regarding pelvic fractures sustained during snowboarding is scant.

Purpose

To analyze the epidemiologic data, injury patterns, and types of pelvic fractures sustained during snowboarding.

Study Deign

Case series; Level of evidence, 4.

Methods

We analyzed the epidemiologic factors, injury patterns, and types of pelvic fractures in 145 patients with snowboarding-related pelvic fractures who were admitted to our institution from the 1998-1999 to the 2006-2007 ski season.

Results

The incidence of snowboarding-related pelvic fractures was 0.102 per 10 000 ski lift tickets, which amounted to 2% of all snowboarding-related fractures (fifth most common type of fracture among all snowboarding-related fractures). Of the pelvic fractures, 85.5% were stable (type A according to the Tile classification) and 14.5% were unstable (types B and C according to the Tile classification). Isolated sacral fractures had the second-highest incidence (24.1%) after pubic bone and/or ischium fractures (46.9%). A distinct female prevalence was seen (52.4%). Jumps and isolated falls were the main mechanisms of injury (80%), and the incidence of collision was significantly higher in the unstable group than in the stable group (P = .037). In all, 57.9% patients classified their skill level as “intermediate,” and only 9.7% of patients had received professional snowboarding lessons. A total of 30 subjects (20.8%) had other injuries along with pelvic fractures; the patients with multiple injuries were significantly more frequent in the unstable group than in the stable group (P = .035).

Conclusion

Pelvic fractures resulting from snowboarding accidents included a higher proportion with isolated sacral fractures in the stable group and a lower prevalence of associated injuries in the unstable group compared with those resulting from other causes.
In Situ Forces in the Anteromedial and Posterolateral Bundles of the Anterior Cruciate Ligament under Simulated Functional Loading Conditions
Authors: Wu Jia-Lin , Seon Jong Keun , Gadikota Hemanth R. , Hosseini Ali , Sutton Karen M. , Gill Thomas J. , Li Guoan
Published: January 2010

Background

The in situ forces of the anteromedial (AM) and posterolateral bundles (PL) of the anterior cruciate ligament (ACL) under simulated functional loads such as simulated muscle loads have not been reported. These data are instrumental for improvement of the anatomical double-bundle ACL reconstruction.

Hypothesis

The load-sharing patterns of the 2 bundles are complementary under simulated muscle loads.

Study Design

Descriptive laboratory study.

Methods

Eight cadaveric knees in this study were sequentially studied using a robotic testing system. Each knee was tested under 3 external loading conditions including (1) a 134-N anterior tibial load; (2) combined rotational loads of 10 N·m of valgus and 5 N·m internal tibial torques; and (3) a 400-N quadriceps muscle load with the knee at 0°, 15°, 30°, 60°, and 90° of flexion. The in situ forces of the 2 bundles of ACL were determined using the principle of superposition.

Results

Under the anterior tibial load, the PL bundle carried peak loads at full extension and concurrently had significantly lower force than the AM bundle throughout the range of flexion (P < .05). Under the combined rotational loads, the PL bundle contributed to carrying the load between 0° and 30°, although less than the AM bundle. Under simulated muscle loads, both bundles carried loads between 0° and 30°. There was no significant difference between the 2 bundle forces at all flexion angles (P > .05).

Conclusion

Under externally applied loads, in general, the AM bundle carried a greater portion of the load at all flexion angles, whereas the PL bundle only shared the load at low flexion angles. The bundles functioned in a complementary rather than a reciprocal manner to each other.

Clinical Relevance

The data appear to support the concept that both bundles function in a complementary manner. Thus, how to re-create the 2 bundle functions in an ACL reconstruction should be further investigated.
Biodegradable Screw versus a Press-Fit Bone Plug Fixation for Hamstring Anterior Cruciate Ligament Reconstruction
Authors: Jagodzinski Michael , Geiges Bjoern , von Falck Christian , Knobloch Karsten , Haasper Carl , Brand Juergen , Hankemeier Stefan , Krettek Christian , Meller Rupert
Published: January 2010

Background

Press-fit fixation of a tendon graft has been advocated to achieve tendon-to-bone healing.

Hypothesis

Fixation of hamstring tendon grafts with a porous bone scaffold limits bone tunnel enlargement compared with a biodegradable interference screw fixation.

Study Design

Randomized controlled trial; Level of evidence, 1.

Methods

Between 2005 and 2006, 20 patients (17 men, 3 women) with a primary reconstruction of the anterior cruciate ligament (ACL) were enrolled in this study. Patients were randomized to obtain graft fixation in the tibial tunnel either by means of an interference screw (I) or a press-fit fixation with a porous bone cylinder (P). At 3 months after surgery, a computed tomography (CT) scan of the knee was performed, and tunnel enlargement was analyzed in the coronal and sagittal planes for the proximal, middle, and distal thirds of the tunnel. After 6 months and 1 and 2 years, radiographs of the knee in the sagittal and coronal plane were analyzed for bone tunnel widening. The International Knee Documentation Committee (IKDC), Tegner, and Lysholm scores of both groups were compared after 1 and 2 years.

Results

The bone tunnel enlargement determined by CT was 106.9% ± 10.9% for group P and 121.9% ± 9.0% for group I (P < .02) in the anteroposterior (AP) plane and 102.8% ± 15.2% versus 121.5% ± 10.1% in the coronal plane (P < .01). The IKDC, Tegner, and Lysholm scores improved in both groups from preoperatively to postoperatively without significant differences between the 2 groups. There was a trend to higher knee stability in group P after 3 months (0.6 ± 1.4 mm vs 1.8 ± 1.5 mm; P = .08).

Conclusion

Both interference screw and a press-fit fixation lead to a high number of good or very good outcomes after ACL reconstruction. Tibial press-fit fixation decreases the amount of proximal bone tunnel enlargement.
Novel Approach to Repair of Acute Achilles Tendon Rupture
Authors: Yotsumoto Tadahiko , Miyamoto Wataru , Uchio Yuji
Published: January 2010

Background

Immobilization or orthosis is required after conventional Achilles tendon surgery.

Hypothesis

This new Achilles tendon repair approach enables early rehabilitation without any postoperative immobilization or orthosis.

Study Design

Case series; Level of evidence, 4.

Methods

Twenty consecutive patients (14 men and 6 women; mean age, 43.4 years; range, 16-70 years) who had acute subcutaneous Achilles tendon rupture were treated by the new method, with an average follow-up of 2.9 years (range, 2-4.8 years). Among them, 15 injuries were sports-related and 5 were work-related. The authors applied a side-locking loop technique of their own design for the core suture, using braided polyblend suture thread, with peripheral cross-stitches added. The patients started active and passive ankle mobilization from the next day, partial weightbearing walking from 1 week, full-load walking from 4 weeks, and double-legged heel raises from 6 weeks after surgery.

Results

The range of motion recovery equal to the intact side averaged 3.2 weeks. Double-legged heel raises and 20 continuous singlelegged heel raise exercises were possible at an average of 6.3 weeks and 9.9 weeks, respectively. T2-weighted magnetic resonance signal intensity recovered to equal that of the intact portion of the same tendon at 12 weeks. The patients resumed sports activities or heavy labor at an average of 14.4 weeks. The Achilles tendon rupture score averaged 98.3 at 24 weeks. There were no complications.

Conclusion

This new Achilles tendon repair approach enables early mobilization exercise without costly specialized orthosis or immobilization and allows an early return to normal life and sports activities, reducing the physical and economic burden on patients.
Focal Cartilage Defects in the Knee Impair Quality of Life as Much as Severe Osteoarthritis
Authors: Heir Stig , Nerhus Tor K. , Røtterud Jan H. , Løken Sverre , Ekeland Arne , Engebretsen Lars , Årøen Asbjørn
Published: December 2009

Background

Patients with focal cartilage defects in the knee may suffer from both pain and functional impairment. Treatment options are often insufficient. It is not known, however, to what extent their complaints affect quality of life, compared with other knee disorders. Knee Injury and Osteoarthritis Outcome Score (KOOS) is a validated global knee score suitable for comparison of patients with knee complaints attributable to different causes.

Hypothesis

Complaints because of localized cartilage defects in the knee reduce quality of life measured by KOOS to a different extent than those due to anterior cruciate ligament deficiency and osteoarthritis, when comparing patients within the working population scheduled for surgery.

Study Design

Cross-sectional study; Level of evidence, 3.

Methods

Previously registered KOOS baseline data on patients enrolled in different knee treatment studies were included in the present study; the patients were 18 to 67 years of age (working population) at data registration. The different patient categories were (1) patients with knee osteoarthritis enrolled for knee arthroplasty, (2) patients with knee osteoarthritis enrolled for osteotomies around the knee, (3) patients with focal cartilage lesions enrolled for cartilage repair, and (4) patients with anterior cruciate ligament—deficient knees enrolled for anterior cruciate ligament reconstruction. The KOOS subscale quality of life was the main parameter for comparison of complaints.

Results

At preoperative baseline, patients with focal cartilage defects in the knee scored 27.5 on the KOOS subscale quality of life, not significantly different from the 28.8 and 27.2 in the patients with osteoarthritis enrolled for knee osteotomies and arthroplasties, respectively. For all the subscales of KOOS, the cartilage patients scored significantly lower than the patients with anterior cruciate ligament deficiency.

Conclusion

Patients with focal cartilage lesions have major problems with pain and functional impairment. Their complaints are worse than those of patients with anterior cruciate ligament—deficient knees, and quality of life is affected to the same extent as in patients scheduled for knee replacement.
Giftedness Is Not What It Used to Be, School Is Not What It Used to Be, Their Future, and Why Psychologists in Education Should Care
Authors: Shore Bruce M.
Published: December 2009

For some three decades psychologists and educators have been working with incomplete or outdated ideas of what constitutes giftedness. Conceptual leadership in the field has moved from a definition based on IQ to expertise- and cognitive science-based definitions. Practice lags behind. Similarly, curriculum concepts are changing to foci based on thinking processes and cognitive apprenticeships, communities of learners, teachers and students as coconstructors of curriculum, and inquiry skills and knowledge as explicit parts of the objectives. Practice there also lags behind, but the shift is underway. This discussion elaborates on these two evolving phenomena, illustrated especially by studies completed and underway in the author’s laboratory group at McGill. It juxtaposes central ideas in gifted education, expertise, and inquiry-driven teaching and learning, and illustrates how these strands can come together for the benefit of all students—albeit sometimes in different ways.
Attributions and Coping Styles in Reducing Victimization
Authors: Shelley Danielle , Craig Wendy M.
Published: December 2009

To examine the role of attributions and coping on children’s victimization over time, 220 children completed questionnaires twice over a 6-month period. Direct and mediational models were tested using regressions, cross-sectionally and longitudinally. Characterological self-blame was positively related to victimization within and across time for boys and girls. Depressive attributions were positively related to victimization only for girls. No coping styles were associated with reduced victimization over time for boys, whereas social support coping was for girls. Avoidant, revenge, and social support coping were positively related to victimization for boys. Avoidant coping directly predicted victimization for girls. No coping styles were significant mediators over time, which suggests situational mechanisms are relevant. Support emerged for strategies for girls to reduce victimization; more research is needed to help boys.