bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structurally modified poly(vinyl alcohol) ionic composites as efficient humidity indicators
Authors: Mujahid Adnan , Afzal Adeel , Ahmad Mirza Nadeem , Farooq Muhammad Umar , Hussain Tajamal , Shehzad Khurram , Shah Asma Tufail 
Published: May 2012

AbstractSynthesis of structurally modified poly(vinyl alcohol) (PVA) ionic composites is presented. Low‐molecular‐weight PVA (Mn = 18,000 g mol−1) is prepared and blended together with either copper or borate ions under ambient conditions to yield PVA–Cu and PVA–B ionic composites, respectively. The borate ions coalesce together with different polymeric chains of PVA, forming a 3D network structure, which is identified by the weakening of OH absorption in the infrared spectrum. On the other hand, copper ions yield a weakly crosslinked polyelectrolyte by forming a coordinated complex with the hydroxyl groups of PVA, which leads to an increase in the λmax value in the ultraviolet–visible spectrum. The surface morphology of these PVA‐based ionic composites is studied via atomic force microscopy. Furthermore, the quantitative estimation of copper in PVA–Cu composites is performed by atomic absorption spectroscopy. Among these PVA ionic composites, the PVA–Cu exhibits excellent moisture absorption capability and dramatic changes in the color of thin composite film, when exposed to 75% humidity atmosphere. The absolute recovery, recyclability, and stability of the PVA–Cu ionic composites not only enable them to be good humidity indicators but the results show that these composites can be employed as efficient humidity‐sensitive material on suitable transducers for environmental and industrial applications. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers
An Improved CTAB–Ammonium Acetate Method for Total RNA Isolation from Cotton
Authors: Zhao Lu , Ding Qi , Zeng Jun , Wang Fu‐Rong , Zhang Jun , Fan Shou‐Jin , He Xin‐Qiang 
Published: May 2012

ABSTRACTIntroductionCotton is an important economic crop. Genetic, developmental and molecular studies of cotton require high‐quality total RNA from different tissues. Due to the richness in polyphenols and polysaccharides, the Trizol‐based methods and other commercial kits are unsuitable for RNA isolation from cotton. Available methods are generally laborious and time‐consuming.ObjectiveTo develop an easy, simple and rapid cetyltrimethylammonium bromide (CTAB)–ammonium acetate protocol that takes less time and obtains high yield and quality of RNA from polysaccharide‐ and polyphenol‐rich cotton tissues.MethodologyBased on the original CTAB protocol, we used phenol–chloroform and chloroform–isoamyl alcohol to remove proteins, polysaccharides and polyphenols, and ammonium acetate to precipitate RNA, reducing the incubation time prior to RNA precipitation. After adding ammonium acetate to precipitate RNA, all centrifugation steps (14000 × g) were carried out at 4°C to avoid degradation.ResultsThe procedure took only 1.5 h and was suitable for different cotton tissues. The A260:A280 ratios ranged from 1.80 to 1.85 with clear 28 s and 18 s ribosomal RNA bands in 1.2% agarose gel. The isolated RNA was usable for downstream molecular studies, such as reverse transcription polymerase chain reaction (PCR) and real‐time quantitative PCR.ConclusionThe CTAB–ammonium acetate method is easy, rapid, low‐cost and effective for high‐quality RNA isolation from polysaccharide‐ and polyphenol‐rich cotton tissues. Copyright © 2012 John Wiley & Sons, Ltd.
Prenatal diagnosis of HbE‐Lepore and Hb Lepore‐β‐thalassemia: the importance of accurate genotyping of the couple at risk
Authors: Italia Khushnooma , Sheth Jayesh , Sawant Pratibha , Nadkarni Anita , Ghosh Kanjaksha , Colah Roshan 
Published: May 2012

ABSTRACTObjectiveTo accurately define unusual genotypes in compound heterozygotes for hemoglobinopathies before undergoing prenatal diagnosis.MethodsThe HPLC results showed one of the parents in case A and B and a child in case C to be HbE‐beta‐thalassemia. However, this finding did not correlate with molecular findings. Further screening of their grandparents and analysis of DNA for HbLepore were performed.ResultsThe presence of a typical hump in the peak in the HbA2 window (10–15%) in one of the grandparents led to the suspicion of a large deletion. Further molecular screening for HbLepore concluded that case A was compound heterozygous for HbLepore‐Hollandia‐(δ22/β50) and HbE, case B for HbLepore‐Boston‐Washington‐(δ287/β116) and IVS‐I‐5(G > C) and case C for HbLepore‐Hollandia‐(δ22/β50) and HbE. The fetuses were found to be HbE trait in case A and HbLepore trait in case B and C.ConclusionAccurate genotyping of the couple at risk referred for prenatal diagnosis is important to identify uncommon genotypic combinations in compound heterozygous cases. Extended family studies are often useful to avoid misdiagnosis of the fetus. © 2012 John Wiley & Sons, Ltd.
Attitudes toward non‐invasive prenatal diagnosis among pregnant women and health professionals in Japan
Authors: Yotsumoto Junko , Sekizawa Akihiko , Koide Keiko , Purwosunu Yuditiya , Ichizuka Kiyotake , Matsuoka Ryu , Kawame Hiroshi , Okai Takashi 
Published: May 2012

ABSTRACTObjectiveThis study aims to assess the attitudes toward non‐invasive prenatal diagnosis (NIPD) and NIPD problems in clinical practice in Japan.MethodsA mail‐in survey using a self‐reported questionnaire was conducted among pregnant women and health professionals. The questionnaire enquired about attitudes, concerns, and expectations regarding NIPD.ResultsThe responses from 252 respondents revealed that pregnant women have more positive attitudes toward NIPD than health professionals. In addition, there were wide discrepancies in concerns and expectations about NIPD, between medical professionals and pregnant women. The respondents with less NIPD knowledge had a more positive attitude toward the clinical application of NIPD. There was concern expressed by clinical geneticists whether an NIPD test should be performed or not when there is a lack of knowledge about the NIPD. All of the health professionals emphasized the importance of providing genetic counseling prior to and after the testing.ConclusionPregnant women place importance on the safety and non‐invasiveness of the NIPD tests, whereas medical professionals consider the diagnostic accuracy and reliability of the test to be the most important. Health professionals pointed out that the tests might be frequently performed without the pregnant women having adequate knowledge or counseling. © 2012 John Wiley & Sons, Ltd.
Evaluation of total hip arthroplasty devices using a total joint replacement registry
Authors: Paxton Elizabeth W. , Ake Christopher F. , Inacio Maria C.S. , Khatod Monti , Marinac‐Dabic Danica , Sedrakyan Art 
Published: May 2012

ABSTRACTPurposeThe purpose of this paper is to describe the infrastructure of the total joint replacement registry of a large integrated healthcare system's and emphasize challenges associated with orthopedic device classification and evaluation.MethodsUsing a large integrated healthcare system innovative infrastructure including electronic health record data, administrative data sources, and registry data collection, we evaluated device choice and outcomes of total hip arthroplasty (THA). Devices were classified into type of bearing surface (alternative versus traditional). Multiple imputation was used to accommodate missing data, and a logistic regression model was applied to assess the impact of patient and surgeon factors on choice of bearing surface. A Cox regression model was used to evaluate risk of aseptic revision while controlling for surgeon, site, and patient characteristics. Adjusted cumulative probability‐of‐event curves were created, comparing survival of alternative against traditional bearings of devices, with aseptic revision as the outcome of interest.ResultsThe study sample consisted of 25 377 primary THAs with an average follow‐up of 2.7 years. Choice of bearing surface varied by surgeon and patient characteristics. After adjusting for patient, surgeon, and hospital covariates, results showed that the risk of aseptic revision associated with alternative bearings did not differ significantly from traditional bearing surfaces (hazard ratio = 1.33; 95% confidence interval: 0.90, 1.98).ConclusionsClinically rich data from a registry with linkages to electronic health records and other administrative databases improve identification of exposures, outcomes, and patient subgroups in medical device evaluation. These various data sources facilitate refined adjustment for potential confounders such as hospital, surgeon, and patient factors and ensure comprehensive device performance evaluation within registries. Copyright © 2012 John Wiley & Sons, Ltd.
Role of disease risk scores in comparative effectiveness research with emerging therapies
Authors: Glynn Robert J. , Gagne Joshua J. , Schneeweiss Sebastian 
Published: May 2012

ABSTRACTBackgroundUsefulness of propensity scores and regression models to balance potential confounders at treatment initiation may be limited for newly introduced therapies with evolving use patterns.ObjectivesTo consider settings in which the disease risk score has theoretical advantages as a balancing score in comparative effectiveness research because of stability of disease risk and the availability of ample historical data on outcomes in people treated before introduction of the new therapy.MethodsWe review the indications for and balancing properties of disease risk scores in the setting of evolving therapies and discuss alternative approaches for estimation. We illustrate development of a disease risk score in the context of the introduction of atorvastatin and the use of high‐dose statin therapy beginning in 1997, based on data from 5668 older survivors of myocardial infarction who filled a statin prescription within 30 days after discharge from 1995 until 2004. Theoretical considerations suggested development of a disease risk score among nonusers of atorvastatin and high‐dose statins during the period 1995–1997.ResultsObserved risk of events increased from 11% to 35% across quintiles of the disease risk score, which had a C‐statistic of 0.71. The score allowed control of many potential confounders even during early follow‐up with few study endpoints.ConclusionsBalancing on a disease risk score offers an attractive alternative to a propensity score in some settings such as newly marketed drugs and provides an important axis for evaluation of potential effect modification. Joint consideration of propensity and disease risk scores may be valuable. Copyright © 2012 John Wiley & Sons, Ltd.
Identification of metastatic cancer in claims data
Authors: Nordstrom Beth L. , Whyte Joanna L. , Stolar Marilyn , Mercaldi Catherine , Kallich Joel D. 
Published: May 2012

ABSTRACTPurposeTo develop algorithms to identify metastatic cancer in claims data, using tumor stage from an oncology electronic medical record (EMR) data warehouse as the gold standard.MethodsData from an outpatient oncology EMR database were linked to medical and pharmacy claims data. Patients diagnosed with breast, lung, colorectal, or prostate cancer with a stage recorded in the EMR between 2004 and 2010 and with medical claims available were eligible for the study. Separate algorithms were developed for each tumor type using variables from the claims, including diagnoses, procedures, drugs, and oncologist visits. Candidate variables were reviewed by two oncologists. For each tumor type, the selected variables were entered into a classification and regression tree model to determine the algorithm with the best combination of positive predictive value (PPV), sensitivity, and specificity.ResultsA total of 1385 breast cancer, 1036 lung, 727 colorectal, and 267 prostate cancer patients qualified for the analysis. The algorithms varied by tumor type but typically included International Classification of Diseases‐Ninth Revision codes for secondary neoplasms and use of chemotherapy and other agents typically given for metastatic disease. The final models had PPV ranging from 0.75 to 0.86, specificity 0.75–0.97, and sensitivity 0.60–0.81.ConclusionsWhile most of these algorithms for metastatic cancer had good specificity and acceptable PPV, a tradeoff with sensitivity prevented any model from having good predictive ability on all measures. Results suggest that accurate ascertainment of metastatic status may require access to medical records or other confirmatory data sources. Copyright © 2012 John Wiley & Sons, Ltd.
Analyzing partially missing confounder information in comparative effectiveness and safety research of therapeutics
Authors: Toh Sengwee , García Rodríguez Luis A. , Hernán Miguel A. 
Published: May 2012

ABSTRACTPurposeElectronic healthcare databases are commonly used in comparative effectiveness and safety research of therapeutics. Many databases now include additional confounder information in a subset of the study population through data linkage or data collection. We described and compared existing methods for analyzing such datasets.MethodsUsing data from The Health Improvement Network and the relation between non‐steroidal anti‐inflammatory drugs and upper gastrointestinal bleeding as an example, we employed several methods to handle partially missing confounder information.ResultsThe crude odds ratio (OR) of upper gastrointestinal bleeding was 1.50 (95% confidence interval: 0.98, 2.28) among selective cyclo‐oxygenase‐2 inhibitor initiators (n = 43 569) compared with traditional non‐steroidal anti‐inflammatory drug initiators (n = 411 616). The OR dropped to 0.81 (0.52, 1.27) upon adjustment for confounders recorded for all patients. When further considering three additional variables missing in 22% of the study population (smoking, alcohol consumption, body mass index), the OR was between 0.80 and 0.83 for the missing‐category approach, the missing‐indicator approach, single imputation by the most common category, multiple imputation by chained equations, and propensity score calibration. The OR was 0.65 (0.39, 1.09) and 0.67 (0.38, 1.16) for the unweighted and the inverse probability weighted complete‐case analysis, respectively.ConclusionsExisting methods for handling partially missing confounder data require different assumptions and may produce different results. The unweighted complete‐case analysis, the missing‐category/indicator approach, and single imputation require often unrealistic assumptions and should be avoided. In this study, differences across methods were not substantial, likely due to relatively low proportion of missingness and weak confounding effect by the three additional variables upon adjustment for other variables. Copyright © 2012 John Wiley & Sons, Ltd.
Performance of propensity score methods when comparison groups originate from different data sources
Authors: Hammill Bradley G. , Curtis Lesley H. , Setoguchi Soko 
Published: May 2012

ABSTRACTPurposeTo examine the performance of propensity score‐based methods for estimating relative risks when exposed and comparison subjects are selected from different data sources.MethodsWe conducted Monte Carlo simulations to assess the performance of propensity score methods under various scenarios in which exposed and comparison subjects were selected from different data sources for a comparative effectiveness study of a medical device.ResultsThe use of propensity score methods in our simulated data scenarios often yielded estimates of relative risk that were close to the true effect, unless the comparison group differed from the exposed group systematically on a factor associated with the outcome. This situation caused severe bias regardless of which method was used but could be overcome if the exposed group could be restricted similarly to the comparison group. Mean square error of relative risk estimates was lowest for similarly restricted study groups and when the comparison group could be considered a random sample of the source population that generated the exposed group.ConclusionsWhen exposed and comparison groups originated from different data sources, all propensity score methods yielded relatively unbiased and consistent estimates of relative risk in most situations reflected in our simulation study. Copyright © 2012 John Wiley & Sons, Ltd.
Simulation study of instrumental variable approaches with an application to a study of the antidiabetic effect of bezafibrate
Authors: Cai Bing , Hennessy Sean , Flory James H. , Sha Daohang , Ten Have Thomas R. , Small Dylan S. 
Published: May 2012

ABSTRACTPurposeWe studied the application of the generalized structural mean model (GSMM) of instrumental variable (IV) methods in estimating treatment odds ratios (ORs) for binary outcomes in pharmacoepidemiologic studies and evaluated the bias of GSMM compared to other IV methods.MethodsBecause of the bias of standard IV methods, including two‐stage predictor substitution (2SPS) and two‐stage residual inclusion (2SRI) with binary outcomes, we implemented another IV approach based on the GSMM of Vansteelandt and Goetghebeur. We performed simulations under the principal stratification setting and evaluated whether GSMM provides approximately unbiased estimates of the causal OR and compared its bias and mean squared error to that of 2SPS and 2SRI. We then applied different IV methods to a study comparing bezafibrate versus other fibrates on the risk of diabetes.ResultsOur simulations showed that unlike the standard logistic, 2SPS, and 2SRI procedures, our implementation of GSMM provides an approximately unbiased estimate of the causal OR even under unmeasured confounding. However, for the effect of bezafibrate versus other fibrates on the risk of diabetes, the GSMM and two‐stage approaches yielded similarly attenuated and statistically non‐significant OR estimates. The attenuation of the OR by the two‐stage and GSMM IV approaches suggests unmeasured confounding, although violations of the IV assumptions or differences in the parameters estimated could be playing a role.ConclusionThe GSMM IV approach provides approximately unbiased adjustment for unmeasured confounding on binary outcomes when a valid IV is available. Copyright © 2012 John Wiley & Sons, Ltd.
One‐to‐many propensity score matching in cohort studies
Authors: Rassen Jeremy A. , Shelat Abhi A. , Myers Jessica , Glynn Robert J. , Rothman Kenneth J. , Schneeweiss Sebastian 
Published: May 2012

ABSTRACTBackgroundAmong the large number of cohort studies that employ propensity score matching, most match patients 1:1. Increasing the matching ratio is thought to improve precision but may come with a trade‐off with respect to bias.ObjectiveTo evaluate several methods of propensity score matching in cohort studies through simulation and empirical analyses.MethodsWe simulated cohorts of 20 000 patients with exposure prevalence of 10%–50%. We simulated five dichotomous and five continuous confounders. We estimated propensity scores and matched using digit‐based greedy (“greedy”), pairwise nearest neighbor within a caliper (“nearest neighbor”), and a nearest neighbor approach that sought to balance the scores of the comparison patient above and below that of the treated patient (“balanced nearest neighbor”). We matched at both fixed and variable matching ratios and also evaluated sequential and parallel schemes for the order of formation of 1:n match groups. We then applied this same approach to two cohorts of patients drawn from administrative claims data.ResultsIncreasing the match ratio beyond 1:1 generally resulted in somewhat higher bias. It also resulted in lower variance with variable ratio matching but higher variance with fixed. The parallel approach generally resulted in higher mean squared error but lower bias than the sequential approach. Variable ratio, parallel, balanced nearest neighbor matching generally yielded the lowest bias and mean squared error.Conclusions1:n matching can be used to increase precision in cohort studies. We recommend a variable ratio, parallel, balanced 1:n, nearest neighbor approach that increases precision over 1:1 matching at a small cost in bias. Copyright © 2012 John Wiley & Sons, Ltd.
Active Layer Characteristics At Ten Borehole Sites In Alpine Permafrost Terrain, Switzerland
Authors: Zenklusen Mutter Evelyn , Phillips Marcia 
Published: May 2012

ABSTRACTThis study investigates and compares active layer characteristics determined from ground temperature measurements at ten borehole sites in various types of Alpine permafrost terrain. Active layer thickness (ALT) remained fairly constant at the individual boreholes over the past five to 14 years, but was highly variable among the sites due to local terrain characteristics. To allow intra‐site comparisons, a characteristic depth within the active layer was determined for each site. The temperature series either measured or interpolated for that depth were used to investigate different thermal stages during the annual thawing and refreezing cycle. The relation between air temperature thawing‐degree days and ALT was investigated on an annual, seasonal and daily basis. The results show that at least daily data are required to establish the relevant characteristics of active layer development. Periods of slow advance of the thaw plane, interpreted as being due to the presence of ice‐bearing layers within the active layer, are particularly important to the final ALT. Rapid active layer deepening, however, can occur due to the formation of taliks caused by lateral thermal disturbances below the active layer. Copyright © 2012 John Wiley & Sons, Ltd.
Soil Organic Carbon and Its Relationship to Vegetation Communities and Soil Properties in Permafrost Areas of the Central Western Qinghai‐Tibet Plateau, China
Authors: Wu Xiaodong , Zhao Lin , Chen Meijun , Fang Hongbing , Yue Guangyang , Chen Ji , Pang Qiangqiang , Wang Zhiwei , Ding Yongjian 
Published: May 2012

ABSTRACTSoil organic carbon (SOC) contents were examined beneath two grassland vegetation communities and cold desert sites in permafrost areas of the central western part of the Qinghai‐Tibet Plateau. Mean SOC stocks in the top 150 cm were 7.73 kg m‐2 for Stipa roborowskyi communities and 3.72 kg m‐2 for Carex moorcroftii communities, but only 1.84 kg m‐2 for cold alpine desert. More than 80 per cent of SOC stocks beneath the grasslands were in the top 100 cm. Correlation analyses showed that SOC stocks in the top 150 cm are linked to soil moisture content, and the vertical distribution of SOC is mainly affected by depth and soil moisture content. Moisture content and vegetation communities are therefore important factors associated with SOC content in this cold, arid area, while active‐layer thickness, vegetation cover and topographical factors play non‐significant roles in SOC distribution. Copyright © 2012 John Wiley & Sons, Ltd.
Taming the Beast: Measurement of the Enthalpies of Combustion and Formation of Triacetone Triperoxide (TATP) and Diacetone Diperoxide (DADP) by Oxygen Bomb Calorimetry
Authors: Contini Alessandro E. , Bellamy Anthony J. , Ahad Leila N. 
Published: May 2012

AbstractLow‐melting paraffin wax was successfully used as a phlegmatizing agent to perform semi‐micro oxygen bomb calorimetry of spectroscopically pure samples of the sensitive explosive peroxides TATP and DADP. The energies of combustion (ΔcU) were measured and the standard enthalpies of formation (ΔfH°) were derived using the CODATA values for the standard enthalpies of formation of the combustion products. Whilst the measured ΔfH° of DADP (ΔfH°=−598.5 ± 39.7 kJ mol−1) could not be compared to any existing literature value, the measured ΔfH° value of TATP (ΔfH°=+151.4 ± 32.7 kJ mol−1) did not correlate well with the only existing experimental value and confirmed that TATP is an endothermic cyclic peroxide.