bluuebunny/crossref_metadata_2025_split huggingface dataset:
Three enigmatic examples and inference from likelihood
Authors: Fraser D. A. S. , Wong A. , Sun Y. 
Published: May 2009

AbstractStatistics has many inference procedures for examining a model with data to obtain information concerning the value of a parameter of interest. If these give different results for the same model and data, one can reasonably want a satisfactory explanation. Over the last eighty years, three very simple examples have appeared intermittently in the literature, often with contradictory or misleading results; these enigmatic examples come from Cox, Behrens, and Box & Cox. The procedures in some generality begin with an observed likelihood function, which is known to provide just first order accuracy unless there is additional information that calibrates the parameter. In particular, default Bayes analysis seeks such calibration in the form of a model‐based prior; such a prior with second order accuracy is examined for the Behrens problem, but none seems available for the Box and Cox problem. Alternatively, higher‐order likelihood theory obtains such information by examining likelihood at and near the data and achieves third order accuracy. We examine both Bayesian and frequentist procedures in the context of the three enigmatic examples; simulations support the indicated accuracies. The Canadian Journal of Statistics © 2009 Statistical Society of Canada
Bootstrap tests for variance components in generalized linear mixed models
Authors: Sinha Sanjoy K. 
Published: May 2009

AbstractIn many applications of generalized linear mixed models to clustered correlated or longitudinal data, often we are interested in testing whether a random effects variance component is zero. The usual asymptotic mixture of chi‐square distributions of the score statistic for testing constrained variance components does not necessarily hold. In this article, the author proposes and explores a parametric bootstrap test that appears to be valid based on its estimated level of significance under the null hypothesis. Results from a simulation study indicate that the bootstrap test has a level much closer to the nominal one while the asymptotic test is conservative, and is more powerful than the usual asymptotic score test based on a mixture of chi‐squares. The proposed bootstrap test is illustrated using two sets of real‐life data obtained from clinical trials. The Canadian Journal of Statistics © 2009 Statistical Society of Canada
Likelihood analysis of joint marginal and conditional models for longitudinal categorical data
Authors: Chen Baojiang , Yi Grace Y. , Cook Richard J. 
Published: May 2009

AbstractThe authors develop a Markov model for the analysis of longitudinal categorical data which facilitates modelling both marginal and conditional structures. A likelihood formulation is employed for inference, so the resulting estimators enjoy the optimal properties such as efficiency and consistency, and remain consistent when data are missing at random. Simulation studies demonstrate that the proposed method performs well under a variety of situations. Application to data from a smoking prevention study illustrates the utility of the model and interpretation of covariate effects. The Canadian Journal of Statistics © 2009 Statistical Society of Canada
Robust transformation mixed‐effects models for longitudinal continuous proportional data
Authors: Zhang Peng , Qiu Zhenguo , Fu Yuejiao , Song Peter X.‐K. 
Published: May 2009

AbstractThe authors propose a robust transformation linear mixed‐effects model for longitudinal continuous proportional data when some of the subjects exhibit outlying trajectories over time. It becomes troublesome when including or excluding such subjects in the data analysis results in different statistical conclusions. To robustify the longitudinal analysis using the mixed‐effects model, they utilize the multivariate t distribution for random effects or/and error terms. Estimation and inference in the proposed model are established and illustrated by a real data example from an ophthalmology study. Simulation studies show a substantial robustness gain by the proposed model in comparison to the mixed‐effects model based on Aitchison's logit‐normal approach. As a result, the data analysis benefits from the robustness of making consistent conclusions in the presence of influential outliers. The Canadian Journal of Statistics © 2009 Statistical Society of Canada
Data‐driven choice of the smoothing parametrization for kernel density estimators
Authors: Chacón José E. 
Published: May 2009

AbstractThere are several levels of sophistication when specifying the bandwidth matrix H to be used in a multivariate kernel density estimator, including H to be a positive multiple of the identity matrix, a diagonal matrix with positive elements or, in its most general form, a symmetric positive‐definite matrix. In this paper, the author proposes a data‐based method for choosing the smoothing parametrization to be used in the kernel density estimator. The procedure is fully illustrated by a simulation study and some real data examples. The Canadian Journal of Statistics © 2009 Statistical Society of Canada
Longitudinal Changes in the B‐Type Natriuretic Peptide Levels in Normal Pregnancy and Postpartum
Authors: Hameed Afshan Batool , Chan Kenneth , Ghamsary Mark , Elkayam Uri 
Published: May 2009

AbstractNormal levels of B‐type natriuretic peptide (BNP) are not well established in pregnancy. We obtained longitudinal BNP levels in 29 healthy pregnant women in each trimester and postpartum period, and compared these levels to the 25 nonpregnant controls. There were no significant differences among the cases and controls with respect to weight, diastolic blood pressure, and ethnicity. A total of 116 BNP values were obtained during pregnancy. The median (and range) BNP level during pregnancy was 19 (10–143) pg/ml versus 10 (10–37) pg/ml in the nonpregnant controls (p = 0.003). However, there were no statistically significant differences in the median BNP levels at various stages of pregnancy: first trimester 20 (10–115) pg/ml versus the second trimester 18 (10–112) pg/ml (p = 0.8), second trimester 18 pg/ml versus third trimester 26 (10–143) pg/ml (p = 0.06), and third trimester 26 pg/ml versus postpartum18 (10–62) pg/ml (p = 0.08). There were no significant differences between the BNP levels throughout the trimesters and postpartum period. Pregnant BNP levels were approximately twice as high as the nonpregnant BNP levels. Our study is unique in evaluating longitudinal changes in BNP levels in normal pregnancies and the postpartum period in comparison with healthy, nonpregnant controls. It demonstrates that pregnant BNP levels are approximately 2‐fold higher than their nonpregnant counterparts, and do not significantly fluctuate during pregnancy. In conclusion, pregnancy is associated with a significant, but small increase in the BNP levels compared with nonpregnant women. Copyright © 2009 Wiley Periodicals, Inc.
Electrocardiographic Abnormalities in Young Athletes with Mitral Valve Prolapse
Authors: Markiewicz‐Łoskot Grażyna , Łoskot Maria , Moric‐Janiszewska Ewa , Dukalska Maria , Mazurek BogusŁaw , Kohut Joanna , SzydŁowski LesŁaw 
Published: May 2009

AbstractBackgroundMitral valve prolapse (MVP) is the most common primary valvular abnormality in a young population. In some individuals, MVP is silent or associated with palpitations, dizziness, chest pain, and abnormal electrocardiogram (ECG) repolarization with or without ventricular arrhythmias.HypothesisThe aim of the present study was to assess the occurrence of the clinical and electrocardiographic abnormalities in young athletes with silent MVP.MethodsA group of 10 children, who have been sport training intensively, with preparticipation silent MVP were examined for symptoms and/or ECG abnormalities. The diagnosis of MVP was made by echocardiography.ResultsThree athletes were asymptomatic at initial presentation. The other 7 athletes presented with symptoms. The QTc intervals > 440 msec were recorded in 2 athletes (1 with syncope). Abnormal ECG repolarization was found in 7 athletes (4 athletes were symptomatic and 3 were asymptomatic). A large variety of T‐waves was registered in athletes who presented with symptoms. In asymptomatic athletes, the tall and flat T‐waves were recorded.ConclusionsYoung athletes with MVP are often predisposed to electrocardiographic abnormalities of ventricular repolarization, which requires annual cardiologic evaluation. Copyright © 2009 Wiley Periodicals, Inc.
Twelve Months Clinical Outcome of Drug‐Eluting Stents Implantation or Coronary Artery Bypass Surgery for the Treatment of Diabetic Patients with Multivessel Disease
Authors: Qiao Yan , Ma Changsheng , Nie Shaoping , Liu Xiaohui , Kang Junping , Lv Qiang , Du Xin , Hu Rong , Zhang Yin , Jia Changqi , Liu Xinmin , Dong Jianzeng , Chen Fang , Zhou Yujie , Lv Shuzheng , Huang Fangjiong , Gu Chengxiong , Wu Xuesi 
Published: May 2009

AbstractBackgroundStudies comparing coronary artery bypass grafting (CABG) with drug‐eluting stent (DES) for the treatment of diabetic patients with multivessel disease are relatively scarce although controversies exist concerning the relative efficacy of CABG versus DES.HypothesisThe aim of this study was to evaluate the effect of drug‐eluting stent (DES) implantation in diabetic patients with multivessel disease compared with CABG.MethodsWe included 645 consecutive diabetic patients who underwent either CABG (n = 282) or DES implantation (n = 363) in our institution from July 2003 to December 2005.ResultsAt 12 mo after index revascularization procedure, the total mortality rate was similar in the CABG and DES group (3.2% versus 3.0%, hazard ratio [HR] of CABG versus percutaneous coronary intervention [PCI] 0.58, 95% confidence interval [CI]: 0.14 to 2.45, p = 0.460), but the rate of major adverse cardiac cerebrovascular events was lower in the CABG group (7.8% versus 17.9%, HR: 0.15, 95% CI: 0.06 to 0.37, p < 0.001) mainly due to less repeat revascularization with CABG (1.4% versus 11.6%, HR: 0.02, 95% CI: 0.01 to 0.13, p < 0.001). Age, 3‐vessel disease, and serum creatinine ≥1.5 mg/dl were positive independent predictors of 12 mo death.ConclusionsAt 12 mo, CABG was associated with less adverse events primarily due to less repeat revascularization compared with DES although there was no significant difference in mortality and myocardial infarction (MI) rates between the 2 groups; high repeat revascularization rate related to DES resulted from high restenosis rate in diabetic patients and lower rate of complete revascularization offered by PCI. Copyright © 2009 Wiley Periodicals, Inc.
Unusual Presentation of Nickel Allergy Requiring Explantation of an Amplatzer Atrial Septal Occluder Device
Authors: Rabkin David G. , Whitehead Kevin J. , Michaels Andrew D. , Powell Douglas L. , Karwande S.V. 
Published: May 2009

AbstractSystemic allergic reaction to a percutaneous patent foramen ovale (PFO) occlusion device is a rare event with only scattered reports in the literature. Serious allergic reactions to these devices have a poorly defined incidence, presentation, and natural history. We present a woman with a previously unknown nickel allergy who developed severe chest pain beginning the morning after percutaneous device closure of the PFO. Despite multiple visits to her cardiologists and primary care physicians, the cause of her chest pain remained unclear. After seeking a second opinion at our medical center, skin testing showed a severe reaction to nickel. These symptoms were refractory to treatment until device explantation 18 mo later. This case highlights the importance of recognizing nickel allergy as a cause of chest pain following implantation of certain types of devices used for closure of PFOs and other heart defects. Copyright © 2009 Wiley Periodicals, Inc.
Diastolic Function Predicts Outcome After Aortic Valve Replacement in Patients with Chronic Severe Aortic Regurgitation
Authors: Çaylı Murat , Kanadaşı Mehmet , Akpınar Onur , Usal Ayhan , Poyrazoglu Hakan 
Published: May 2009

AbstractBackgroundDue to eccentric hypertrophy and fibrosis, patients with severe aortic regurgitation (AR) have diastolic dysfunction. Increased fibrosis correlates with increased myocardial stiffness and worsening of diastolic function. Patients with irreversible left ventricular (LV) dysfunction have severe myocardial fibrosis and myocyte apoptosis and do not benefit from aortic valve replacement (AVR).HypothesisTo investigate whether diastolic properties of LV predicts outcome after AVR in patients with chronic severe AR and LV systolic dysfunction.MethodsThe study population consisted of 41 patients with chronic severe AR and LV systolic dysfunction. Preoperative echocardiographic examinations were repeated at the postoperative 6th month. Left ventricular ejection fraction (LVEF) was calculated. Diastolic function was evaluated with Doppler echocardiography. Patients were classified as Group 1 (impaired relaxation), Group 2 (pseudonormalization), and Group 3 (restrictive pattern).ResultsPostoperative LVEF was significantly increased in Group 1, whereas it tended to decrease in Group 3. Left ventricular size was significantly decreased in Group 1 and 2 during the postoperative period. Multivariate linear regression analysis showed that deceleration time and early/late ratio were independent predictors of postoperative changes in LVEF.ConclusionsAssessment of diastolic function is a reliable parameter in predicting outcome of AVR in patients with chronic AR and systolic dysfunction. Copyright © 2009 Wiley Periodicals, Inc.
Long‐Term Survival and Outcomes After Hospitalization for Acute Myocardial Infarction Complicated by Cardiogenic Shock
Authors: Drakos Stavros G. , Bonios Michael J. , Anastasiou‐Nana Maria I. , Tsagalou Eleftheria P. , Terrovitis John V. , Kaldara Elisabet , Maroulidis George , Nanas Serafim N. , Kanakakis John , Nanas John N. 
Published: May 2009

AbstractBackgroundCardiogenic shock is the leading cause of death during hospitalization for acute myocardial infarction (MI). However, little data exist regarding the long‐term outcomes of patients who survived the acute phase of MI and were discharged from the hospital.MethodsWe retrospectively reviewed the records of 81 consecutive patients referred for management of acute MI and cardiogenic shock to analyze their in‐hospital and long‐term outcomes.ResultsMean systemic systolic and central venous pressures at presentation were 74 ± 15 and 17 ± 7 mm Hg, respectively. Intra‐aortic balloon counterpulsation (IABC) was implemented in all patients for a mean of 88 ± 83 hours. Thrombolytics were administered in 49% and mechanical ventilation applied in 46% of patients. Primary angioplasty could not be performed in any patient, while 17 patients later underwent myocardial revascularization during hospitalization. There were 37 in‐hospital survivors (45.7%). The 1‐year survival after discharge from the hospital was 87.6% in the overall population, versus 100% among patients who underwent in‐hospital myocardial revascularization, versus 78.9% among nonrevascularized patients (p = 0.079). Over a mean follow‐up of 85 ± 47 mo, survival after discharge from the index hospitalization was 44.9% in the overall population, versus 56.2% among revascularized patients, versus 36.4% among nonrevascularized patients (p = 0.277). Heart failure developed in 51.6% of patients who were discharged from the hospital.ConclusionsIn this single center analysis, the long‐term survival after acute MI complicated by cardiogenic shock was high with nearly 50% of patients surviving free from heart failure. Copyright © 2009 Wiley Periodicals, Inc.
Propionibacterium acnes Endocarditis of a Prosthetic Aortic Valve
Authors: List Richard J. , Sheikh Nabeel , Theologou Thomas , Mitchell Ian M. , Mathew Thomas 
Published: May 2009

AbstractIn the few reported cases of Propionibacterium infective endocarditis involving prosthetic aortic valves, abscess is common and frequently requires surgery. We report a case of P. acnes infective endocarditis idtified on prolonged blood cultures with aortic root abscess involving a Starr‐Edwards valve. Intravenous antibiotics and valve replacement led to recovery. Copyright © 2009 Wiley Periodicals, Inc.
Prologue
Authors: Cardillo Mark J. 
Published: May 2009

AbstractThe Camille & Henry Dreyfus Foundation, chartered in 1946 by Camille Dreyfus as a tribute to his brother and partner in science, Henry, hosted Climate, Energy, and the Changing Environment: A Dreyfus Foundation Symposium on Environmental Chemistry Research, at the New York Academy of Sciences in October 2008. After having awarded ca. 100 fellowships, it seemed an appropriate time to assess the status of this rapidly growing field.magnified image
Cover Picture: Towards the Efficient, Total Glycan Utilization of Biomass (ChemSusChem 5/2009)
Authors: Mascal Mark , Nikitin Edward B. 
Published: May 2009

AbstractThe cover picture shows common sources of waste biomass (agricultural, municipal, forestry) being processed into a mixture of substituted furans in the biomass digester described by M. Mascal and E. B. Nikitin in their Communication on page 423. The method is remarkably simple and is based on a biphasic reactor incorporating a solvent extraction loop. Isolated product yields from raw biomass approach 90 % of the theoretical, from which can be derived new generation “furanoline” biofuels such as 5‐ethoxymethylfurfural and 5‐methylfurfural, as well as the value‐added products furfural and levulinic acid (picture courtesy of Gorkem Gunbas, Department of Chemistry, UC Davis).magnified image
Dynamics of Patterns in Nonlinear Equivariant PDEs
Authors: Beyn Wolf‐Jürgen , Thümmler Vera 
Published: May 2009

AbstractMany solutions of nonlinear time dependent partial differential equations show particular spatio‐temporal patterns, such as traveling waves in one space dimension or spiral and scroll waves in higher space dimensions. The purpose of this paper is to review some recent progress on the analytical and the numerical treatment of such patterns. Particular emphasis is put on symmetries and on the dynamical systems viewpoint that goes beyond existence, uniqueness and numerical simulation of solutions for single initial value problems. The nonlinear asymptotic stability of dynamic patterns is discussed and a numerical approach (the freezing method) is presented that allows to compute co‐moving frames in which solutions converging to the patterns become stationary. The results are related to the theory of relative equilibria for equivariant evolution equations. We discuss several applications to parabolic systems with nonlinearities of FitzHugh‐Nagumo and Ginzburg‐Landau type (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spectral Theory for Perturbed Systems
Authors: Colonius Fritz , Kliemann Wolfgang 
Published: May 2009

AbstractThis paper presents an overview of topological, smooth, and control techniques for dynamical systems and their interrelations for the study of perturbed systems. We concentrate on spectral analysis via linearization of systems. Emphasis is placed on parameter dependent perturbed systems and on a comparison of the Markovian and the dynamical structure of systems with Markov diffusion perturbation process. A number of applications is provided (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Tethered satellite systems: A challenge for mechanics and applied mathematics
Authors: Schwarzbart Michael , Steindl Alois , Steiner Wolfgang , Troger Hans , Wiedermann Georg 
Published: May 2009

AbstractTethered satellite systems that is two or more satellites in orbit connected by thin long cables, pose a number of challenging problems in mechanics concerning modeling and derivation of the equations of motion and in applied mathematics, concerning the numerical simulation of their dynamics, deciding on stability of relative equilibria and the proof of chaotic dynamics. We also compare for the practically important process of deployment of one satellite from another satellite uncontrolled deployment with steered deployment, according to Pontrijagin's Maximum Principle. Related to the stability of relative equilibria, as example the Space elevator, which is a tethered system extending from the surface of the Earth beyond geostationary height, is considered (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
V(D)J targeting mistakes occur at low frequency in acute lymphoblastic leukemia
Authors: Vanura Katrina , Vrsalovic Maruska Marusic , Le Trang , Marculescu Rodrig , Kusec Rajko , Jäger Ulrich , Nadel Bertrand 
Published: May 2009

AbstractTranslocations of proto‐oncogenes to the B‐cell or T‐cell antigen receptor loci in acute T‐ or B‐cell leukemia and lymphoma have been, in most cases, accredited to V(D)J or switch recombination depending on the location of the breakpoint at the receptor locus. Only in rare instances, the reports take into account mechanistic characteristics of the translocation mechanism. To assess the functional ability of several sites implicated in supposedly V(D)J‐mediated translocations, we tested five sites at four proto‐oncogene loci in an ex vivo recombination substrate assay for their potential to act as direct target for V(D)J recombination. Our results show that the LMO2/RBTN2/TTG2 site and one LCK/P56 site readily engage in recombination with a genuine TCR element with the majority of breakpoint junctions showing the characteristics of V(D)J recombination, which strongly supports the involvement of this mechanism in the pathogenesis of the corresponding translocations in vivo. The site at the TLX1/HOX11 locus yielded 0.8% V(D)J‐specific junctions. Sites at the LCK/P56 and TCF3/E2A proto‐oncogenes resulted in exclusively unspecific breakpoints scattered over part of or the entire proto‐oncogene region tested, marking them as unlikely V(D)J recombination targets. Our data suggest that, while being a potentially dangerous mechanism due to the introduction of DNA breaks, V(D)J recombination is a tightly controlled mechanism allowing for only few direct mistakes. © 2009 Wiley‐Liss, Inc.
Arachidonic acid: A key molecule for astrocyte survival to peroxynitrite
Authors: Palomba Letizia , Cerioni Liana , Cantoni Orazio 
Published: May 2009

AbstractNontoxic concentrations of peroxynitrite (ONOO−) nevertheless commit rat astrocytes to mitochondrial permeability transition‐dependent toxicity, however prevented by a signaling response driven by arachidonic acid (ARA). The lipid messenger was released upon ONOO−‐dependent activation of cytosolic phospholipase A2 and its pharmacological inhibition, or knock‐down, was invariably associated with a prompt apoptotic response sensitive to exogenous ARA, but insensitive to other polyunsaturated fatty acids, as eicosapentaenoic or linoleic acid. Interestingly, while microglia also used ARA to cope with ONOO−, cerebellar granule cells were killed by the same concentrations of ONOO− employed in astrocyte/microglia experiments via a mechanism sensitive to inhibition of ARA release. These results collectively support the notion that resistance of glial cells to ONOO−, a species extensively produced under neuroinflammatory conditions, is largely based on a critical survival signaling triggered by the inflammatory product ARA. In remarkable contrast with these results, the lipid messenger appears to mediate toxicity in neuronal cells. © 2009 Wiley‐Liss, Inc.