bluuebunny/crossref_metadata_2025 huggingface dataset:
Optofluidic Raman sensor for simultaneous detection of the toxicity and quality of alcoholic beverages
Authors: Ashok Praveen C. , Praveen Bavishna B. , Dholakia Kishan
Published: April 2013

We report a chemometric prediction of the toxicity and quality of liquor using an optofluidic sensor based upon Waveguide Confined Raman Spectroscopy (WCRS). The WCRS sensor was used to record the Raman spectra, each obtained from a 20 µl sample of a given alcoholic beverage with and acquisition time of 20 s. This was used to predict, simultaneously, both the methanol concentration (toxicity) and ethanol concentration (quality), with an accuracy of 0.1% and 0.7% by volume, respectively, using a Partial Least Squares‐based chemometric model. The model sensor is shown to be capable of identifying toxic liquors, based on the test performed on different types of liquor samples. Copyright © 2013 John Wiley & Sons, Ltd.
Common and rare alleles of the serotonin transporter gene, SLC6A4, associated with Tourette's disorder
Authors: Moya Pablo R. , Wendland Jens R. , Rubenstein Liza M. , Timpano Kiara R. , Heiman Gary A. , Tischfield Jay A. , King Robert A. , Andrews Anne M. , Ramamoorthy Samanda , McMahon Francis J. , Murphy Dennis L.
Published: April 2013

To evaluate the hypothesis that functionally over‐expressing alleles of the serotonin transporter (SERT) gene (solute carrier family 6, member 4, SLC6A4) are present in Tourette's disorder (TD), just as we previously observed in obsessive compulsive disorder (OCD), we evaluated TD probands (N = 151) and controls (N = 858). We genotyped the refined SERT‐linked polymorphic region 5‐HTTLPR/rs25531 and the associated rs25532 variant in the SLC6A4 promoter plus the rare coding variant SERT isoleucine‐to‐valine at position 425 (I425V). The higher expressing 5‐HTTLPR/rs25531 LA allele was more prevalent in TD probands than in controls (χ2 = 5.75; P = 0.017; odds ratio [OR], 1.35); and, in a secondary analysis, surprisingly, it was significantly more frequent in probands who had TD alone than in those who had TD plus OCD (Fisher's exact test; P = 0.0006; OR, 2.29). Likewise, the higher expressing LAC haplotype (5‐HTTLPR/rs25531/rs25532) was more frequent in TD probands than in controls (P = 0.024; OR, 1.33) and also in the TD alone group versus the TD plus OCD group (P = 0.0013; OR, 2.14). Furthermore, the rare gain‐of‐function SERT I425V variant was observed in 3 male siblings with TD and/or OCD and in their father. Thus, the cumulative count of SERT I425V becomes 1.57% in OCD/TD spectrum conditions versus 0.15% in controls, with a recalculated, family‐adjusted significance of χ2 = 15.03 (P < 0.0001; OR, 9.0; total worldwide genotyped, 2914). This report provides a unique combination of common and rare variants in one gene in TD, all of which are associated with SERT gain of function. Thus, altered SERT activity represents a potential contributor to serotonergic abnormalities in TD. The present results call for replication in a similarly intensively evaluated sample. © 2013 Movement Disorder Society
Ultrashort echo time bi‐component analysis of cortical bone—a field dependence study
Authors: Li Shihong , Chang Eric Y. , Bae Won C. , Chung Christine B. , Gao Song , Bao Shanglian , Bydder Graeme M. , Hua Yanqing , Du Jiang
Published: April 2013

Purpose

The purpose of this study is to investigate the effect of differing field strength on the
of cortical bone at 1.5 T and 3 T.

Methods

Ultrashort echo time pulse sequences were used to study six bovine and nine human bone samples at 1.5 T and 3 T using single‐ and bi‐component
analysis.

Results

On average, the bound water
of bovine bone decreased by 16% (from 0.32 ms at 1.5 T to 0.27 ms at 3 T, P < 0.01) and the bound water
of human bone decreased by 21% (from 0.42 ms at 1.5 T to 0.33 ms at 3 T, P < 0.01) at the higher field strength. The free water
of bovine bone decreased by 50% (from 4.23 ms at 1.5 T to 2.12 ms at 3 T, P < 0.001) and the free water
of human bone decreased by 68% (from 7.65 ms at 1.5 T to 2.46 ms at 3 T, P < 0.001) at the higher field strength. Bound and free water fractions showed only minor change with field strength in bovine (< 2%, P > 0.05) and human bone (< 4%, P > 0.05).

Conclusion

Ultrashort echo time bi‐component analysis provides consistent bound and free water fractions at 1.5 T and 3 T, thereby allowing field‐independent comparisons. Magn Reson Med 71:1075–1081, 2014. © 2013 Wiley Periodicals, Inc.
Assessment of slope stability in cohesive soils due to a rainfall
Authors: Pietruszczak S. , Haghighat E.
Published: April 2013

The primary focus in this work is on proposing a methodology for the assessment of stability of natural/engineered slopes in clayey soils subjected to water infiltration. In natural deposits of fine‐grained soils, the presence of water in the vicinity of minerals results in an interparticle bonding. This effect cannot be easily quantified as it involves complex chemical interactions at the micromechanical level. Here, the evolution of strength properties, including the apparent cohesion resulting from initial suction at the irreducible fluid saturation, is described by employing the framework of chemoplasticity. The paper provides first the formulation of the problem; this involves specification of the constitutive relation, development of an implicit return mapping scheme, and the outline of a coupled transient formulation. The framework is then applied to examine the stability of a slope subjected to a prolonged period of intensive rainfall. It is shown that the water infiltration may trigger the loss of stability resulting from the degradation of material properties. Copyright © 2013 John Wiley & Sons, Ltd.
Finding the extreme Z‐eigenvalues of tensors via a sequential semidefinite programming method
Authors: Hu Shenglong , Huang Zheng‐Hai , Qi Liqun
Published: April 2013

In this paper, we first introduce the tensor conic linear programming (TCLP), which is a generalization of the space TCLP. Then an approximation method, by using a sequence of semidefinite programming problems, is proposed to solve the TCLP. In particular, we reformulate the extreme Z‐eigenvalue problem as a special TCLP. It gives a numerical algorithm to compute the extreme Z‐eigenvalue of an even order tensor with dimension larger than three, which improves the literature. Numerical experiments show the efficiency of the proposed method. Copyright © 2013 John Wiley & Sons, Ltd.
The geographic concentration of us adult obesity prevalence and associated social, economic, and environmental factors
Authors: Slack Tim , Myers Candice A. , Martin Corby K. , Heymsfield Steven B.
Published: April 2013

Objective

This study used spatial statistical methods to test the hypotheses that county‐level adult obesity prevalence in the United States is (1) regionally concentrated at significant levels, and (2) linked to local‐level factors, after controlling for state‐level effects.

Methods

Data were obtained from the Centers for Disease Control and Prevention and other secondary sources. The units of analysis were counties. The dependent variable was the age‐adjusted percentage of adults who were obese in 2009 (body mass index >30 kg/m2).

Results

The prevalence of county‐level obesity varied from 13.5% to 47.9% with a mean of 30.3%. Obesity prevalence across counties was not spatially random: 15.8% belonged to high‐obesity regions and 13.5% belonged to low‐obesity regions. Obesity was positively associated with unemployment, outpatient healthcare visits, physical inactivity, female‐headed families, black populations, and less education. Obesity was negatively correlated with physician numbers, natural amenities, percent ≥65 years, Hispanic populations, and larger population size. A number of variables were notable for not reaching significance after controlling for other factors, including poverty and food environment measures.

Conclusions

The findings demonstrate the importance of local‐level factors in explaining geographic variation in obesity prevalence, and thus hold implications for geographically targeted interventions to combat the obesity epidemic.
The significance of the second trimester sonographic soft markers in pregnancies after normal first trimester screening
Authors: Kaijomaa Marja , Ulander Veli‐Matti , Ryynanen Markku , Stefanovic Vedran
Published: April 2013

What's already known about this topic?

Fetuses with soft markers have slightly increased risk of aneuploidy in high‐risk pregnancies. The value of soft markers after normal first trimester screening in general obstetric population is still conflicting.

What does this study add?

Soft markers have very limited or no value in screening for aneuploidy in singleton pregnancies after normal first trimester screening and without a priori high‐risk for aneuploidy.
Brand name or generic? What are the health professionals prescribed for treating diabetes? A longitudinal analysis of the National Health Insurance reimbursement database
Authors: Liou Wen‐Shyong , Hsieh Shu‐Ching , Chang Wai‐Yuan , Wu Grace Hui‐Min , Huang Hsu‐Shan , Lee Chuanfang
Published: April 2013

Objective

This study aimed to explore whether physicians prescribe more brand‐name oral hypoglycemic agents (OHA) for diabetic patients with medical training background (MP) than for general patients (GP).

Research design and methods

A longitudinal analysis of 1 000 000 National Health Insurance cohorts of 1998–2008 was conducted. Univariate and multivariate models were performed to assess the associations of the outcome (the ratio of brand‐name/generic odds in the MP group to that in the GP group) and the covariates, including patient medical training background, characteristics of patient, prescriber, and medical settings, and market competition. A generalized estimating equation method was used to control the dependency of longitudinal data.

Results

A total of 46 850 diabetic patients were prescribed with 2 703 149 OHA prescriptions during the study period. Compared with GP, MP had 1.37 times greater odds of being prescribed with brand‐name instead of generic OHA, among whom pharmacists and physicians had the highest odds ratios of 2.78 (95%CI, 1.05–7.36) and 1.68 (95%CI, 0.99–2.85), respectively. Patients' diabetes severity, prescribers' level of experience, medical settings that were publicly owned, had a higher accreditation level, and were located in a higher urbanized area, lower market competition, and earlier dates of prescription were positively associated with brand‐name prescription. Among all medical sub‐specialties, cardiologists were more likely to prescribe brand‐name OHA.

Conclusions

This study is the first to demonstrate how a patients' medical training background, in addition to the characteristics of patients, prescribers, and medical settings, and market competition might influence physicians' prescribing choice of brand‐name or generic OHA. Copyright © 2013 John Wiley & Sons, Ltd.
A simulation study to compare three self‐controlled case series approaches: correction for violation of assumption and evaluation of bias
Authors: Hua Wei , Sun Guoying , Dodd Caitlin N. , Romio Silvana A. , Whitaker Heather J. , Izurieta Hector S. , Black Steven , Sturkenboom Miriam C. J. M. , Davis Robert L. , Deceuninck Genevieve , Andrews N. J.
Published: April 2013

Purpose

The assumption that the occurrence of outcome event must not alter subsequent exposure probability is critical for preserving the validity of the self‐controlled case series (SCCS) method. This assumption is violated in scenarios in which the event constitutes a contraindication for exposure. In this simulation study, we compared the performance of the standard SCCS approach and two alternative approaches when the event‐independent exposure assumption was violated.

Methods

Using the 2009 H1N1 and seasonal influenza vaccines and Guillain‐Barré syndrome as a model, we simulated a scenario in which an individual may encounter multiple unordered exposures and each exposure may be contraindicated by the occurrence of outcome event. The degree of contraindication was varied at 0%, 50%, and 100%. The first alternative approach used only cases occurring after exposure with follow‐up time starting from exposure. The second used a pseudo‐likelihood method.

Results

When the event‐independent exposure assumption was satisfied, the standard SCCS approach produced nearly unbiased relative incidence estimates. When this assumption was partially or completely violated, two alternative SCCS approaches could be used. While the post‐exposure cases only approach could handle only one exposure, the pseudo‐likelihood approach was able to correct bias for both exposures.

Conclusions

Violation of the event‐independent exposure assumption leads to an overestimation of relative incidence which could be corrected by alternative SCCS approaches. In multiple exposure situations, the pseudo‐likelihood approach is optimal; the post‐exposure cases only approach is limited in handling a second exposure and may introduce additional bias, thus should be used with caution. Copyright © 2013 John Wiley & Sons, Ltd.
Isotactic poly(propylene‐co‐1‐pentene‐co‐1‐hexene) terpolymers: Synthesis, molecular characterization, and evidence of the trigonal polymorph
Authors: García‐Peñas Alberto , Gómez‐Elvira José M. , Pérez Ernesto , Cerrada María L.
Published: April 2013

Terpolymers based on propylene with 1‐pentene and 1‐hexene as comonomeric units are satisfactorily synthesized using a metallocene catalyst. Thus, several terpolymers are prepared with distinct overall compositions in comonomers as well as three different 1‐pentene/1‐hexene ratios at a given composition to evaluate the influence on polymerization activity, intrinsic viscosity, and microstructural details. The new trigonal δ polymorph is observed in those quenched terpolymers with a global content in comonomers of about 14 mol %, independently of the ratio between both comonomers. However, preliminary results indicate a profound influence of that ratio on the crystallization rate. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3251–3259
Nonlinear depression of the lower critical solution temperatures in aqueous solutions of thermo‐sensitive random copolymers
Authors: Kojima Hiroyuki , Tanaka Fumihiko
Published: April 2013

We develop a theoretical model of cooperative hydration to clarify the molecular origin of the observed nonlinear depression of the lower critical solution temperature (LCST) in the aqueous solutions of thermosensitive random copolymers and find the monomer composition at which LCST shows a minimum. Phase diagrams of poly(N‐isopropylacrylamide‐co‐N,N‐diethylacrylamide) copolymer solutions are theoretically derived on the basis of the theory of cooperative hydration by introducing the microscopic structure parameter η which characterizes the distribution of the monomer sequences along the chains. We compared them with the experimental data of LCST of random copolymers with various monomer compositions and also of the diblock copolymers with equimolar monomer composition. The transition temperature shifts to lower than those of homopolymer counterparts when the monomer sequence of the chains has an alternative tendency. On the contrary, for the blocky polymers such as diblock copolymers, the transition temperature remains almost the same as those of the homopolymers. Thus, the nonlinear effect in phase separation appears when the average block length of the copolymers is shorter than the average sequence length of the cooperative hydration. The degree of hydration is calculated as a function of the temperature and polymer concentration for varied distribution of the copolymer compositions. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 1112–1123
Psychosocial predictors of four health‐promoting behaviors for cancer prevention using the stage of change of Transtheoretical Model
Authors: Choi Jean H. , Chung Kyong‐Mee , Park Keeho
Published: April 2013

Objectives

The present study aimed to examine whether demographic as well as psychosocial variables related to the five stages of change of the Transtheoretical Model can predict non‐clinical adults' cancer preventive and health‐promoting behaviors. This study specifically focused on cancer, one of the major chronic diseases, which is a serious threat of national health.

Methods

A total of 1530 adults participated in the study and completed questionnaires. Collected data were analyzed by using multinominal logistic regression.

Results

The significant predictors of later stages varied among the types of health‐promoting behaviors. Certain cancer preventive health‐promoting behaviors such as well‐balanced diet and exercise were significantly associated with psychosocial variables including cancer prevention‐related self‐efficacy, personality traits, psychosocial stress, and social support. On the other hand, smoking cessation and moderate or abstinence from drinking were more likely to be predicted by demographic variables including sex and age.

Conclusions

The present study found that in addition to self‐efficacy—a relatively well‐studied psychological variable—other personality traits and psychological factors including introversion, neuroticism, psychosocial stress, and social support also significantly predicted later stages of change with respect to cancer preventive health‐promoting behaviors. The implications of this study are also discussed. Copyright © 2013 John Wiley & Sons, Ltd.
Couples facing advanced cancer: examination of an interdependent relational system
Authors: Lo Chris , Hales Sarah , Braun Michal , Rydall Anne C. , Zimmermann Camilla , Rodin Gary
Published: April 2013

Background

The relational impact of advanced cancer on both patients and spouse caregivers has rarely been examined simultaneously. This study describes a framework for understanding distress in each partner as a consequence of psychosocial characteristics, burden of disease or of caregiving, and the distress of the other person. A model focusing on the protective value of social relatedness was tested to illustrate the interdependence of patients and spouses in their mutual adaptation to disease.

Methods

A total of 278 advanced cancer patients and their spouse caregivers completed measures of psychological distress (e.g., depression), physical burden from cancer (e.g., symptom count), caregiving burden (i.e., time and task demand), and social relatedness (i.e., social support and attachment security). Structural equation modeling was used to extract latent factors associated with these constructs and to examine their interrelationships.

Results

The model fit was adequate. Patient distress was related to disease burden (standardized path coefficient = 0.52) and patient social relatedness (−0.32). Caregiver distress was related to caregiving burden (0.21) and caregiver social relatedness (−0.51). Caregiving burden was related to patient disease burden (0.43) and caregiver social relatedness (−0.37). Reciprocal pathways between patient and caregiver distress indicated that caregiver distress was influenced by patient distress (0.30) but not vice versa (0.12).

Conclusions

These findings support the view that patients and caregivers constitute an interdependent relational system and interventions in this setting should take into account both interactions between patients and caregivers and the nature of their social relatedness. Copyright © 2013 John Wiley & Sons, Ltd.
Heterogeneous Nanoassembling: Microfluidically Prepared Poly(methyl methacrylate) Nanoparticles on Ag Microrods and ZnO Microflowers
Authors: Visaveliya Nikunjkumar , Li Shuning , Köhler J. Michael
Published: April 2013

The heterogeneous assembly of colloidal polymer particles on the nano‐ and microstructures of a metal is a versatile platform for adjusting the mechanical and electrical properties simultaneously. The assemblies of silver (Ag) microrods and flower‐like zinc oxide (ZnO) microparticles with poly(methyl methacrylate) (PMMA) nanospheres are presented to prepare advanced composite materials. PMMA nanoparticles are prepared via the emulsion polymerization technique using a microfluidic preparation step in the presence of cationic surfactant. The surface charge of PMMA particles determines the binding interaction strength with inorganic constituents. Ag microrods and ZnO microparticles are prepared in a batch and in a continuous flow process, respectively. The assembling process can be explained by a particle–particle binding process due to the electrostatic interaction for both types of nanoassemblies. The observed binding pattern reveals certain lateral mobility of the small polymer particles at the surface of larger metal particle. The particle ratios in the nanoassemblies can be tuned over a wide range by changing the reaction parameters.
Lipase in aqueous‐polar organic solvents: Activity, structure, and stability
Authors: Kamal Md. Zahid , Yedavalli Poornima , Deshmukh Mandar V. , Rao Nalam Madhusudhana
Published: April 2013

Studying alterations in biophysical and biochemical behavior of enzymes in the presence of organic solvents and the underlying cause(s) has important implications in biotechnology. We investigated the effects of aqueous solutions of polar organic solvents on ester hydrolytic activity, structure and stability of a lipase. Relative activity of the lipase monotonically decreased with increasing concentration of acetone, acetonitrile, and DMF but increased at lower concentrations (upto ∼20% v/v) of dimethylsulfoxide, isopropanol, and methanol. None of the organic solvents caused any appreciable structural change as evident from circular dichorism and NMR studies, thus do not support any significant role of enzyme denaturation in activity change. Change in 2D [15N, 1H]‐HSQC chemical shifts suggested that all the organic solvents preferentially localize to a hydrophobic patch in the active‐site vicinity and no chemical shift perturbation was observed for residues present in protein's core. This suggests that activity alteration might be directly linked to change in active site environment only. All organic solvents decreased the apparent binding of substrate to the enzyme (increased Km); however significantly enhanced the kcat. Melting temperature (Tm) of lipase, measured by circular dichroism and differential scanning calorimetry, altered in all solvents, albeit to a variable extent. Interestingly, although the effect of all organic solvents on various properties on lipase is qualitatively similar, our study suggest that magnitudes of effects do not appear to follow bulk solvent properties like polarity and the solvent effects are apparently dictated by specific and local interactions of solvent molecule(s) with the protein.
Tutorial on combustible dust
Authors: Myers Timothy J. , Ibarreta Alfonso F.
Published: April 2013

This article provides an overview of combustible dust. A summary of recent combustible dust incidents and the variety of types of materials that can represent a combustible dust hazard when present in a particulate form are provided. Fundamentals of combustible dust are covered, comparing and contrasting combustible dust to flammable gases and vapors. Test methods used to characterize the hazards of combustible dust are reviewed. Relevant standards and regulations are described. Finally, guidance on the primary methods to prevent and mitigate combustible dust incidents is summarized. © 2013 American Institute of Chemical Engineers Process Saf Prog 32: 298–306, 2013
An efficient analysis of covariance model for crossover thorough QT studies with period‐specific baseline days
Authors: Lu Kaifeng
Published: April 2013

Baseline adjustment is an important consideration in thorough QT studies for nonantiarrhythmic drugs. For crossover studies with period‐specific baseline days, we propose an analysis of covariance model with change from time‐matched baseline as response, time‐matched baseline for the current treatment, day‐averaged baseline for the current treatment, time‐matched baseline averaged across treatments, and day‐averaged baseline averaged across treatments as covariates. This model adjusts for within‐subject diurnal effects for each treatment and is more efficient than commonly used models for treatment comparisons. We illustrate the benefit using real clinical trial data. Copyright © 2013 John Wiley & Sons, Ltd.
Bayesian design and analysis of composite endpoints in clinical trials with multiple dependent binary outcomes
Authors: Zaslavsky Boris G.
Published: April 2013

The author considers studies with multiple dependent primary endpoints. Testing hypotheses with multiple primary endpoints may require unmanageably large populations. Composite endpoints consisting of several binary events may be used to reduce a trial to a manageable size. The primary difficulties with composite endpoints are that different endpoints may have different clinical importance and that higher‐frequency variables may overwhelm effects of smaller, but equally important, primary outcomes. To compensate for these inconsistencies, we weight each type of event, and the total number of weighted events is counted. To reflect the mutual dependency of primary endpoints and to make the weighting method effective in small clinical trials, we use the Bayesian approach. We assume a multinomial distribution of multiple endpoints with Dirichlet priors and apply the Bayesian test of noninferiority to the calculation of weighting parameters. We use composite endpoints to test hypotheses of superiority in single‐arm and two‐arm clinical trials. The composite endpoints have a beta distribution. We illustrate this technique with an example. The results provide a statistical procedure for creating composite endpoints. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.
Clinical efficiency and reusability of the reciprocating nickel–titanium instruments according to the root canal anatomy
Authors: Park Sung‐Kyung , Kim Young‐Jae , Shon Won‐Jun , You Sung‐Yeop , Moon Young‐Mi , Kim Hyeon‐Cheol , Lee WooCheol
Published: April 2013

The application of the single‐file technique using the reciprocating motion is gaining concern in root canal preparation. The purpose of this research is to compare the efficiency of the reciprocating motion‐employing files (RECIPROC and WaveOne) by measuring the working time for complete canal shaping, and to evaluate their reusability under scanning examinations. One hundred curved root canals of the extracted molars were used. The working length was determined and the glide path was confirmed using a #15 K‐file. Canals shaping was completed to the length either with RECIPROC R25 file (n = 50), or with WaveOne Primary file (n = 50). The time taken for the file to reach the working length was also measured. Each file was repeatedly used in a maximum of 10 canals for comparing the change of the efficiency (shaping time) according to the working length, canal curvature, and number of file re‐use. The deformations or surface defects of the files after the in vitro use were observed using a scanning electron microscope (SEM). There was no difference under the SEM between the 2 file groups with no initiation of micro‐cracks until they were re‐used up to 5 canals. WaveOne Primary file showed significantly shorter working time than RECIPROC R25 (p < 0.05). There was a statistically significant correlation between the working time and three variables. As the working length and the curvature of the canal increased, the shaping time was increased in both file systems. Reusability of these reciprocating instruments might be maximum 5 canals with minimal surface deformations. SCANNING 36:246–251, 2014. © 2013 Wiley Periodicals, Inc.
Large‐scale parametric survival analysis
Authors: Mittal Sushil , Madigan David , Cheng Jerry Q. , Burd Randall S.
Published: April 2013

Survival analysis has been a topic of active statistical research in the past few decades with applications spread across several areas. Traditional applications usually consider data with only a small numbers of predictors with a few hundreds or thousands of observations. Recent advances in data acquisition techniques and computation power have led to considerable interest in analyzing very‐high‐dimensional data where the number of predictor variables and the number of observations range between 104and 106. In this paper, we present a tool for performing large‐scale regularized parametric survival analysis using a variant of the cyclic coordinate descent method. Through our experiments on two real data sets, we show that application of regularized models to high‐dimensional data avoids overfitting and can provide improved predictive performance and calibration over corresponding low‐dimensional models. Copyright © 2013 John Wiley & Sons, Ltd.
Inverse probability weighted estimating equations for randomized trials in transfusion medicine
Authors: Cook Richard J. , Lee Ker‐Ai , Cuerden Meaghan , Cotton Cecilia A.
Published: April 2013

Thrombocytopenia is a condition characterized by extremely low platelet counts, which puts patients at elevated risk of morbidity and mortality because of bleeding. Trials in transfusion medicine are routinely designed to assess the effect of experimental platelet products on patients’ platelet counts. In such trials, patients may receive multiple platelet transfusions over a predefined period of treatment, and a response is available from each such administration. The resulting data comprised multiple responses per patient, and although it is natural to want to use this data in testing for treatment effects, naive analyses of the multiple responses can yield biased estimates of the probability of response and associated treatment effects. These biases arise because only subsets of the patients randomized contribute response data on the second and subsequent administrations of therapy and the balance between treatment groups with respect to potential confounding factors is lost. We discuss the design and analysis issues involved in this setting and make recommendations for the design of future platelet transfusion trials. Copyright © 2013 John Wiley & Sons, Ltd.
How developers perform feature location tasks: a human‐centric and process‐oriented exploratory study
Authors: Wang Jinshui , Peng Xin , Xing Zhenchang , Zhao Wenyun
Published: April 2013

Developers often have to locate the parts of source code that contribute to a specific feature during software maintenance tasks. This activity, referred to as feature location in software engineering, is a human‐intensive and knowledge‐intensive process. Researchers have investigated (semi‐)automatic analysis‐based techniques to assist developers in such feature location activities. However, little work has been carried out on better understanding how developers perform feature location tasks. In this paper, we report an exploratory study of feature location process, consisting of three experiments in which developers were given unfamiliar systems and asked to complete six feature location tasks. Our study suggests that feature location process can be understood hierarchically at three levels of granularity: phase, pattern, and action. Furthermore, our statistical analysis shows that these feature location phases, patterns, and actions can be effectively imparted to junior developers and consequently improve their performance on feature location tasks. Our qualitative observations and interviews also suggest that external factors, for example, human factors, task properties, and in‐process feedbacks, affect the choices and usage of different feature location patterns and actions. Our results open up new opportunities to feature location research, which could lead to better tool support and more rigorous feature location process. Copyright © 2013 John Wiley & Sons, Ltd.
Combined analysis of correlated data when data cannot be pooled
Authors: Jones Elinor M. , Sheehan Nuala A. , Gaye Amadou , Laflamme Philippe , Burton Paul
Published: April 2013

In genetic epidemiology studies, associations between individual genetic variants and phenotypes of interest are generally weak requiring large samples to estimate effects and to address complex statistical questions. Such sample sizes are often only achievable by pooling data from multiple studies; effects of interest can then be investigated through an individual‐level meta‐analysis (ILMA) on the pooled data, or by conducting a conventional study‐level meta‐analysis (SLMA). However, pooling individual‐level research data for an ILMA is not always possible, and researchers may be compelled to conduct an SLMA instead, restricting the sharing to non‐disclosing summary statistics. In certain settings, an individual‐level analysis can be conducted without pooling the data from the different studies. It has already been shown that when data are horizontally partitioned between studies, i.e. data are collected on the same variables in each study but any given study participant appears in one study only, it is possible to fit a generalised linear model in this way. In the present paper, we demonstrate that an individual‐level generalised estimating equations meta‐analysis can be achieved in an analogous manner. This extends the scope of ILMA without data pooling to problems involving correlated and clustered responses. Copyright © 2013 John Wiley & Sons Ltd
Supraventricular tachyarrhythmia in patients with Brugada syndrome: A single‐center study
Authors: Ohkubo Kimie , Watanabe Ichiro , Okumura Yasuo , Kofune Masayoshi , Nagashima Koichi , Mano Hiroaki , Sonoda Kazumasa , Nakai Toshiko , Kunimoto Satoshi , Kasamaki Yuji , Hirayama Atsushi , Sumitomo Naokata , Nakayama Tomohiro
Published: April 2013

Background

Brugada syndrome is a distinct form of idiopathic ventricular fibrillation. We retrospectively investigated the incidence and clinical implications of supraventricular tachyarrhythmia in patients with Brugada syndrome.

Methods

We reviewed 69 consecutive cases of Brugada syndrome, 11 of which had a history of syncope.

Results

Seven patients (10.1%) had clinically documented supraventricular tachyarrhythmia: 3 patients with atrioventricular reentrant tachycardia, 2 with atrioventricular nodal reentrant tachycardia, and 2 with paroxysmal atrial fibrillation. The prevalence of a spontaneous type 1 Brugada electrocardiogram and symptoms (history of syncope, presyncope, documented ventricular tachyarrhythmia, or aborted sudden cardiac death) were significantly higher, and QRS duration was significantly longer in patients without than in those with supraventricular tachyarrhythmia. The PR and AH intervals were also longer in patients without than in those with supraventricular tachyarrhythmia, but the differences were not statistically significant.

Conclusion

The arrhythmogenic substrate in Brugada syndrome may not be restricted to the ventricles. Palpitations in patients with this syndrome should raise the question of supraventricular tachyarrhythmia. Conversely, in patients with supraventricular tachyarrhythmia and aborted sudden cardiac death or syncope not related to supraventricular tachyarrhythmia, Brugada syndrome should be considered a possible additional electrophysiologic abnormality.
Intravenous pacemaker lead implantation for a pediatric patient: A 16‐year follow‐up study
Authors: Nakamoto Susumu , Fujii Kosuke , Nishino Takako , Satus Takuma , Ogawa Tatsuya , Kaneda Toshio , Saga Toshihiko
Published: April 2013

Intravenous pacemaker lead implantation for small children is not performed routinely. Here, we report the case of a pediatric patient who underwent endocardial lead implantation and follow‐up for 16 years. The patient was a 4‐year‐old boy who underwent total correction of pulmonary atresia with ventricular septal defect following several palliative operations. After the patient underwent total correction, atrial flutter was noted. Atrial flutter was successfully terminated by overdrive pacing. However, atrial flutter occurred again immediately after overdrive pacing. To treat atrial flutter caused by sick sinus syndrome, a screw‐in type lead was attached to the free wall of the right atrium and an excess loop was left to allow for the patient's growth. During the 16‐year follow‐up, no adverse effects were observed except for a gradual increase in pacing threshold. The selection of a small‐sized endocardial lead and an appropriate entry vein, with meticulous management of the leads, makes implantation of an endocardial lead for small children easier and safer.
New gravity–capillary waves at low speeds. Part 1. Linear geometries
Authors: Trinh Philippe H. , Jonathan Chapman S.
Published: April 2013

When traditional linearized theory is used to study gravity–capillary waves produced by flow past an obstruction, the geometry of the object is assumed to be small in one or several of its dimensions. In order to preserve the nonlinear nature of the obstruction, asymptotic expansions in the low-Froude-number or low-Bond-number limits can be derived, but here, the solutions invariably predict a waveless surface at every order. This is because the waves are in fact, exponentially small, and thus beyond-all-orders of regular asymptotics; their formation is a consequence of the divergence of the asymptotic series and the associated Stokes Phenomenon. By applying techniques in exponential asymptotics to this problem, we have discovered the existence of new classes of gravity–capillary waves, from which the usual linear solutions form but a special case. In this paper, we present the initial theory for deriving these waves through a study of gravity–capillary flow over a linearized step. This will be done using two approaches: in the first, we derive the surface waves using the standard method of Fourier transforms; in the second, we derive the same result using exponential asymptotics. Ultimately, these two methods give the same result, but conceptually, they offer different insights into the study of the low-Froude-number, low-Bond-number problem.
The wave instability pathway to turbulence
Authors: Sutherland Bruce R.
Published: April 2013

One way that large-scale oceanic internal waves transfer their energy to small-scale mixing is through parametric subharmonic instability (PSI). But there is a disconnect between theory, which assumes the waves are periodic in space and time, and reality, in which waves are transient and localized. The innovative laboratory experiments and analysis techniques of Bourget et al. (J. Fluid Mech., vol. 723, 2013, pp. 1–20) show that theory can be applied to interpret the generation of subharmonic disturbances from a quasi-monochromatic wave beam. Their methodology and results open up new avenues of investigation into PSI through experiments, simulations and observations.
The influence of dielectric decrement on electrokinetics
Authors: Zhao Hui , Zhai Shengjie
Published: April 2013

We treat the dielectric decrement induced by excess ion polarization as a source of ion specificity and explore its impact on electrokinetics. We employ a modified Poisson–Nernst–Planck (PNP) model accounting for the dielectric decrement. The dielectric decrement is determined by the excess-ion-polarization parameter $\alpha $ and when $\alpha = 0$ the standard PNP model is recovered. Our model shows that ions saturate at large zeta potentials $(\zeta )$. Because of ion saturation, a condensed counterion layer forms adjacent to the charged surface, introducing a new length scale, the thickness of the condensed layer $({l}_{c} )$. For the electro-osmotic mobility, the dielectric decrement weakens the electro-osmotic flow owing to the decrease of the dielectric permittivity. At large $\zeta $, when $\alpha \not = 0$, the electro-osmotic mobility is found to be proportional to $\zeta / 2$, in contrast to $\zeta $ as predicted by the standard PNP model. This is attributed to ion saturation at large $\zeta $. In terms of the electrophoretic mobility ${M}_{e} $, we carry out both an asymptotic analysis in the thin-double-layer limit and solve the full modified PNP model to compute ${M}_{e} $. Our analysis reveals that the impact of the dielectric decrement is intriguing. At small and moderate $\zeta ~({\lt }6kT/ e)$, the dielectric decrement decreases ${M}_{e} $ with increasing $\alpha $. At large $\zeta $, it is known that the surface conduction becomes significant and plays an important role in determining ${M}_{e} $. It is observed that the dielectric decrement effectively reduces the surface conduction. Hence in stark contrast, ${M}_{e} $ increases as $\alpha $ increases. Our predictions of the contrast dependence of the mobility on $\alpha $ at different zeta potentials qualitatively agree with experimental results on the dependence of the mobility among ions and provide a possible explanation for such ion specificity. Finally, the comparisons between the thin-double-layer asymptotic analysis and the full simulations of the modified PNP model suggest that at large $\zeta $ the validity of the thin-double-layer approximation is determined by ${l}_{c} $ rather than the traditional Debye length.
Water entry of a flat elastic plate at high horizontal speed
Authors: Reinhard M. , Korobkin A. A. , Cooker M. J.
Published: April 2013

The two-dimensional problem of an elastic-plate impact onto an undisturbed surface of water of infinite depth is analysed. The plate is forced to move with a constant horizontal velocity component which is much larger than the vertical velocity component of penetration. The small angle of attack of the plate and its vertical velocity vary in time, and are determined as part of the solution, together with the elastic deflection of the plate and the hydrodynamic loads within the potential flow theory. The boundary conditions on the free surface and on the wetted part of the plate are linearized and imposed on the initial equilibrium position of the liquid surface. The wetted part of the plate depends on the plate motion and its elastic deflection. To determine the length of the wetted part we assume that the spray jet in front of the advancing plate is negligible. A smooth separation of the free-surface flow from the trailing edge is imposed. The wake behind the moving body is included in the model. The plate deflection is governed by Euler’s beam equation, subject to free–free boundary conditions. Four different regimes of plate motion are distinguished depending on the impact conditions: (a) the plate becomes fully wetted; (b) the leading edge of the plate touches the water surface and traps an air cavity; (c) the free surface at the forward contact point starts to separate from the plate; (d) the plate exits the water. We could not detect any impact conditions which lead to steady planing of the free plate after the impact. It is shown that a large part of the total energy in the fluid–plate interaction leaves the main bulk of the liquid with the spray jet. It is demonstrated that the flexibility of the plate may increase the hydrodynamic loads acting on it. The impact loads can cause large bending stresses, which may exceed the yield stress of the plate material. The elastic vibrations of the plate are shown to have a significant effect on the fluid flow in the wake.
Reduced-order unsteady aerodynamic models at low Reynolds numbers
Authors: Brunton Steven L. , Rowley Clarence W. , Williams David R.
Published: April 2013

In this paper we develop reduced-order models for the unsteady lift on a pitching and plunging aerofoil over a range of angles of attack. In particular, we analyse the pitching and plunging dynamics for two cases: a two-dimensional flat plate at$\mathit{Re}= 100$using high-fidelity direct numerical simulations and a three-dimensional NACA 0006 aerofoil at$\mathit{Re}= 65\hspace{0.167em} 000$using wind-tunnel measurements. Models are obtained at various angles of attack and they are verified against measurements using frequency response plots and large-amplitude manoeuvres. These models provide a low-dimensional balanced representation of the relevant unsteady fluid dynamics. In simulations, flow structures are visualized using finite-time Lyapunov exponents. A number of phenomenological trends are observed, both in the data and in the models. As the base angle of attack increases, the boundary layer begins to separate, resulting in a decreased quasi-steady lift coefficient slope and a delayed relaxation to steady state at low frequencies. This extends the low-frequency range of motions that excite unsteady effects, meaning that the quasi-steady approximation is not valid until lower frequencies than are predicted by Theodorsen’s classical inviscid model. In addition, at small angles of attack, the lift coefficient rises to the steady-state value after a step in angle, while at larger angles of attack, the lift coefficient relaxes down to the steady-state after an initially high lift state. Flow visualization indicates that this coincides with the formation and convection of vortices at the leading edge and trailing edge. As the angle of attack approaches the critical angle for vortex shedding, the poles and zeros of the model approach the imaginary axis in the complex plane, and some zeros cross into the right half plane. This has significant implications for active flow control, which are discussed. These trends are observed in both simulations and wind-tunnel data.
Rain-induced attenuation of deep-water waves
Authors: Peirson William L. , Beyá José F. , Banner Michael L. , Peral Joaquín Sebastián , Azarmsa Seyed Ali
Published: April 2013

A laboratory investigation has been undertaken to quantify water wave attenuation rates as a function of rainfall rate. Vertical artificial rainfall is shown to generate weak near-surface velocity fluctuations that decline systematically away from the free surface and are independent of rainfall rate across the range of rainfall rates investigated (40–$170~\mathrm{mm} ~{\mathrm{h} }^{- 1} $). In the absence of rain, the observed attenuation of gravity waves is at levels consistent with classical viscous theory, but with a systematic finite-amplitude effect observed above a mean steepness of 0.10. Wave attenuation rates were found to be independent of the mean wave steepness and identical when artificial rainfall rates of 108 and$141~\mathrm{mm} ~{\mathrm{h} }^{- 1} $were applied. Reassessment of complementary theoretical and experimental studies of individual droplets impacting on undisturbed water surfaces indicates that above a weak threshold rainfall rate of$30~\mathrm{mm} ~{\mathrm{h} }^{- 1} $, the surface irradiation becomes so frequent that droplet-generated violent surface motions directly interact with the incoming droplets. Present evidence is that a matching of time scales develops between the incoming surface irradiation and surface water motions generated by antecedent droplets as the rainfall rate increases. Consequently, at high rainfall rates, a highly dissipative surface regime is created that transmits little of the incident rainfall kinetic energy to the aqueous layers below. Rainfall-induced wave attenuation rates are compared with measurements of other wave attenuation processes to obtain a hierarchy of strength in both the laboratory and the field. Comparison is also made with wave attenuation theories that incorporate momentum and energy flux considerations. Rain-induced wave attenuation rates are weak or very strong depending on whether they are expressed in terms of energy scaling obtained from above or below the surface respectively, due to the high dissipation rate that occurs in the vicinity of the interface.