bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optimal design of longitudinal data analysis using generalized estimating equation models
Authors: Liu Jingxia , Colditz Graham A. 
Published: November 2016

Longitudinal studies are often applied in biomedical research and clinical trials to evaluate the treatment effect. The association pattern within the subject must be considered in both sample size calculation and the analysis. One of the most important approaches to analyze such a study is the generalized estimating equation (GEE) proposed by Liang and Zeger, in which “working correlation structure” is introduced and the association pattern within the subject depends on a vector of association parameters denoted by ρ. The explicit sample size formulas for two‐group comparison in linear and logistic regression models are obtained based on the GEE method by Liu and Liang. For cluster randomized trials (CRTs), researchers proposed the optimal sample sizes at both the cluster and individual level as a function of sampling costs and the intracluster correlation coefficient (ICC). In these approaches, the optimal sample sizes depend strongly on the ICC. However, the ICC is usually unknown for CRTs and multicenter trials. To overcome this shortcoming, Van Breukelen et al. consider a range of possible ICC values identified from literature reviews and present Maximin designs (MMDs) based on relative efficiency (RE) and efficiency under budget and cost constraints. In this paper, the optimal sample size and number of repeated measurements using GEE models with an exchangeable working correlation matrix is proposed under the considerations of fixed budget, where “optimal” refers to maximum power for a given sampling budget. The equations of sample size and number of repeated measurements for a known parameter value ρ are derived and a straightforward algorithm for unknown ρ is developed. Applications in practice are discussed. We also discuss the existence of the optimal design when an AR(1) working correlation matrix is assumed. Our proposed method can be extended under the scenarios when the true and working correlation matrix are different.
Increased thalamic centrality and putamen–thalamic connectivity in patients with parkinsonian resting tremor
Authors: Gu Quanquan , Cao Hengyi , Xuan Min , Luo Wei , Guan Xiaojun , Xu Jingjing , Huang Peiyu , Zhang Minming , Xu Xiaojun 
Published: November 2016

AbstractIntroductionEvidence has indicated a strong association between hyperactivity in the cerebello‐thalamo‐motor cortical loop and resting tremor in Parkinson's disease (PD). Within this loop, the thalamus serves as a central hub based on its structural centrality in the generation of resting tremor. To study whether this thalamic abnormality leads to an alteration at the whole‐brain level, our study investigated the role of the thalamus in patients with parkinsonian resting tremor in a large‐scale brain network context.MethodsForty‐one patients with PD (22 with resting tremor, TP and 19 without resting tremor, NTP) and 45 healthy controls (HC) were included in this resting‐state functional MRI study. Graph theory‐based network analysis was performed to examine the centrality measures of bilateral thalami across the three groups. To further provide evidence to the central role of the thalamus in parkinsonian resting tremor, the seed‐based functional connectivity analysis was then used to quantify the functional interactions between the basal ganglia and the thalamus.ResultsCompared with the HC group, patients with the TP group exhibited increased degree centrality (p < .04), betweenness centrality (p < .01), and participation coefficient (p < .01) in the bilateral thalami. Two of these alterations (degree centrality and participation coefficient) were significantly correlated with tremor severity, especially in the left hemisphere (p < .02). The modular analysis showed that the TP group had more intermodular connections between the thalamus and the regions within the cerebello‐thalamo‐motor cortical loop. Furthermore, the data revealed significantly enhanced functional connectivity between the putamen and the thalamus in the TP group (p = .027 corrected for family‐wise error).ConclusionsThese findings suggest increased thalamic centrality as a potential tremor‐specific imaging measure for PD, and provide evidence for the altered putamen–thalamic interaction in patients with resting tremor.
The influence of social identity on value perceptions and intention
Authors: McGowan Miriam , Shiu Edward , Hassan Louise M. 
Published: November 2016

AbstractDespite much research on consumers' brand identification, researchers remain divided regarding the conceptualization of the dimensions underlying social identity and how these dimensions impact marketing outcome variables. Further, previous studies have failed to examine the underlying psychological process driving this effect. The current research is the first to assess the importance of affective social identity as the mediator through which cognitive social identity impacts consumers' purchase intentions by ways of emotional and social value. Results show that affective social identity mediates the relationship between cognitive social identity and emotional value, where affect is the main driver in the formation of purchase intention. This study highlights the need to model cognitive and affective social identity separately and provides insight into how consumers' social identification influences their perceptions of identity‐linked products. Copyright © 2016 John Wiley & Sons, Ltd.
On‐Demand Release of Hydrosoluble Drugs from a Paramagnetic Porous Collagen‐Based Scaffold
Authors: Bettini Simona , Bonfrate Valentina , Madaghiele Marta , Salvatore Luca , Syrgiannis Zois , Giancane Gabriele , Valli Ludovico 
Published: November 2016

AbstractThe design of a collagen scaffold containing iron oxide nanostructures capped by a TiO2 (anatase) layer is reported. The TiO2 shell is proposed to perform a dual role: 1) as an innovative and biocompatible cross‐linker agent, providing binding sites to the protein moiety, through the well‐known TiO2 chemical affinity towards carboxyl groups, and 2) as a protective surface layer for the paramagnetic core against oxidation. Simultaneously, the presence of the nanostructures confers to the collagen gel sensitivity to an external stimulus; that is, the application of a magnetic field. The hybrid biomaterial was demonstrated to be nontoxic and is proposed as a smart scaffold for the release of bioactive compounds on demand. The tuneable release of a model protein (myoglobin) upon application of a magnetic field was investigated. Myoglobin was loaded in the microporous material and discharge was induced by consecutive magnet applications, leading to release of the protein with high spatio–temporal and dosage control.
Reactions Catalysed by a Binuclear Copper Complex: Aerobic Cross Dehydrogenative Coupling of N‐Aryl Tetrahydroisoquinolines
Authors: Liu Yuxia , Wang Chao , Xue Dong , Xiao Miao , Li Chaoqun , Xiao Jianliang 
Published: November 2016

AbstractBinuclear copper complex [{Cu(Sal)2(NCMe)}2] (Sal=salicylate) was found to be an active catalyst for the aerobic oxidation of N‐aryl tetrahydroisoquinolines to the corresponding iminium ions, which could be trapped by a wide range of nucleophiles to form coupled products. The reactions took place under 1 bar of O2 at room temperature with 1 mol % of the copper catalyst being sufficient in most cases, and are considerably accelerated by catalytic chloride anions. Mechanistic studies show that the CuII dimer oxidizes the amine to the iminium ion, and this two‐electron process requires O2, whereby the resulting CuI is concomitantly reoxidised back to CuII. Various lines of evidence suggest that the oxidative coupling reaction is turnover‐limited by the step of iminium formation, and it is this step that is promoted by the chloride anion. Since it is more efficient than and mechanistically distinct from the well‐studied simple copper salts such as CuBr and CuCl2, the binuclear copper catalyst provides a new tool for oxidative coupling reactions.
The multivariate leptokurtic‐normal distribution and its application in model‐based clustering
Authors: Bagnato Luca , Punzo Antonio , Zoia Maria G. 
Published: November 2016

AbstractThis article proposes the elliptical multivariate leptokurtic‐normal (MLN) distribution to fit data with excess kurtosis. The MLN distribution is a multivariate Gram–Charlier expansion of the multivariate normal (MN) distribution and has a closed‐form representation characterized by one additional parameter denoting the excess kurtosis. It is obtained from the elliptical representation of the MN distribution, by reshaping its generating variate with the associated orthogonal polynomials. The strength of this approach for obtaining the MLN distribution lies in its general applicability as it can be applied to any multivariate elliptical law to get a suitable distribution to fit data. Maximum likelihood is discussed as a parameter estimation technique for the MLN distribution. Mixtures of MLN distributions are also proposed for robust model‐based clustering. An EM algorithm is presented to obtain estimates of the mixture parameters. Benchmark real data are used to show the usefulness of mixtures of MLN distributions.The Canadian Journal of Statistics45: 95–119; 2017 © 2016 Statistical Society of Canada
Nitrogen:phosphorous supply ratio and allometry in five alpine plant species
Authors: Luo Xi , Mazer Susan J. , Guo Hui , Zhang Nan , Weiner Jacob , Hu Shuijin 
Published: November 2016

AbstractIn terrestrial ecosystems, atmospheric nitrogen (N) deposition has greatly increased N availability relative to other elements, particularly phosphorus (P). Alterations in the availability of N relative to P can affect plant growth rate and functional traits, as well as resource allocation to above‐ versus belowground biomass (MAandMB). Biomass allocation among individual plants is broadly size‐dependent, and this can often be described as an allometric relationship betweenMAandMB, as represented by the equation, or logMA = logα + βlogMB. Here, we investigated whether the scaling exponent or regression slope may be affected by the N:P supply ratio. We hypothesized that the regression slope betweenMAandMBshould be steeper under a high N:P supply ratio due to P limitation, and shallower under a low N:P supply ratio due to N limitation. To test these hypotheses, we experimentally altered the levels of N, P, and the N:P supply ratio (from 1.7:1 to 135:1) provided to five alpine species representing two functional groups (grasses and composite forbs) under greenhouse conditions; we then measured the effects of these treatments on plant morphology and tissue content (SLA, leaf area, and leaf and root N/P concentrations) and on the scaling relationship betweenMAandMB. Unbalanced N:P supply ratios generally negatively affected plant biomass, leaf area, and tissue nutrient concentration in both grasses and composite forbs. High N:P ratios increased tissue N:P ratios in both functional groups, but more in the two composite forbs than in the grasses. The positive regression slopes between logMAand logMBexhibited by plants raised under a N:P supply ratio of 135:1 were significantly steeper than those observed under the N:P ratio of 1.7:1 and 15:1. Synthesis: Plant biomass allocation is highly plastic in response to variation in the N:P supply ratio. Studies of resource allocation of individual plants should focus on the effects of nutrient ratios as well as the availability of individual elements. The two forb species were more sensitive than grasses to unbalanced N:P supplies. To evaluate the adaptive significance of this plasticity, the effects of unbalanced N:P supply ratio on individual lifetime fitness must be measured.
Microfluidic Electrolyzers for Production and Separation of Hydrogen from Sea Water using Naturally Abundant Solar Energy
Authors: Rarotra Saptak , Mandal Tapas K. , Bandyopadhyay Dipankar 
Published: November 2016

AbstractWe report the design and development of a microfluidic electrolyzer for the continuous production and in situ separation of hydrogen fuel. A series of photovoltaic cells was integrated with a microchannel to produce a high‐intensity electric field under direct solar illumination, which electrolyzed the sea water in the microchannel. The rate of hydrogen production could be varied by tuning the electric field intensity or the flow rate of the sea water. The addition of an outlet near the cathode led to the in situ separation of hydrogen in the straight‐channel electrolyzer. Hydrogen was also separated from oxygen by using a Y‐shaped electrolyzer in which the electrodes were placed on the Y‐arms. The power required for the proposed process was much lower than that of macroscopic analogues because the smaller gap between the electrodes ensured a lower electrical resistance and high‐intensity field inside the microchannel. The large‐scale integration of an array of such electrolyzers could lead to an economic, portable, continuous, and clean pathway to produce hydrogen under ambient conditions.
Harvesting Renewable Energy for Carbon Dioxide Catalysis
Authors: Navarrete Alexander , Centi Gabriele , Bogaerts Annemie , Martín Ángel , York Andrew , Stefanidis Georgios D. 
Published: November 2016

AbstractThe use of renewable energy (RE) to transform carbon dioxide into commodities (i.e., CO2 valorization) will pave the way towards a more sustainable economy in the coming years. But how can we efficiently use this energy (mostly available as electricity or solar light) to drive the necessary (catalytic) transformations? This paper presents a review of the technological advances in the transformation of carbon dioxide by means of RE. The socioeconomic implications and chemical basis of the transformation of carbon dioxide with RE are discussed. Then a general view of the use of RE to activate the (catalytic) transformations of carbon dioxide with microwaves, plasmas, and light is presented. The fundamental phenomena involved are introduced from a catalytic and reaction device perspective to present the advantages of this energy form as well as the inherent limitations of the present state‐of‐the‐art. It is shown that efficient use of RE requires the redesign of current catalytic concepts. In this context, a new kind of reaction system, an energy‐harvesting device, is proposed as a new conceptual approach for this endeavor. Finally, the challenges that lie ahead for the efficient and economical use of RE for carbon dioxide conversion are exposed.
Comparison of antioxidant activities among four kinds of Japanese traditional fermented tea
Authors: Horie Masanori , Nara Kazuhiro , Sugino Sakiko , Umeno Aya , Yoshida Yasukazu 
Published: November 2016

AbstractAntioxidant activities of four kinds of Japanese traditional fermented tea, Gishi‐cha, Ishizuchi‐kurocha, Awa‐bancha, and Batabatacha, were compared. Antioxidant activity was evaluated by three parameters: copper ion reduction ability, radical trapping ability, and oxygen consumption rate. Processes of fermentation of these fermented teas are different. Goichi‐cha and Ishizuchi‐kurocha are produced by a two‐stage fermentation process, aerobic fermentation and subsequent anaerobic fermentation. Awa‐bancha is produced by anaerobic fermentation. And batabata‐cha is produced by aerobic fermentation. Additionally, unfermented green tea was also employed as control. These tea leaves were extracted by boiling water and measured antioxidant activities. And concentrations of caffeine and catechins were measured in green tea and in the four kinds of fermented tea: Ishizuchi‐kurocha, Goishi‐cha, Awa‐Bancha, and Batabata‐cha. Concentrations of caffeine and catechins were lower in the fermented teas than in green tea. Among the fermented teas, epigallocatechin content was the highest in Ishizuchi‐kurocha, whereas Batabata‐cha hardly contained any epigallocatechin. Goichi‐cha, Ishizuchi‐kurocha, and Awa‐bancha showed antioxidative activity regardless of measurement method. Batabatacha had hardly any antioxidative activity. Among the fermented teas, Ishizuchi‐kurocha had the strongest antioxidant activity. The antioxidative activities of green tea and the four kinds of fermented tea were significantly different among each other (p < .01). Implication of this study is as follows: although contents of catechins were lower than that of green tea, three kinds of fermented tea showed antioxidative activity comparable to green tea. The results suggest that anaerobic fermentation process is beneficial at least for antioxidative activity.
fMRI single trial discovery of spatio‐temporal brain activity patterns
Authors: Allegra Michele , Seyed‐Allaei Shima , Pizzagalli Fabrizio , Baftizadeh Fahimeh , Maieron Marta , Reverberi Carlo , Laio Alessandro , Amati Daniele 
Published: November 2016

AbstractThere is growing interest in the description of short‐lived patterns in the spatiotemporal cortical activity monitored via neuroimaging. Most traditional analysis methods, designed to estimate relatively long‐term brain dynamics, are not always appropriate to capture these patterns. Here we introduce a novel data‐driven approach for detecting short‐lived fMRI brain activity patterns. Exploiting Density Peak Clustering (Rodriguez and Laio [2014]), our approach reveals well localized clusters by identifying and grouping together voxels whose time‐series are similar, irrespective of their brain location, even when very short time windows (∼10 volumes) are used. The method, which we call Coherence Density Peak Clustering (CDPC), is first tested on simulated data and compared with a standard unsupervised approach for fMRI analysis, independent component analysis (ICA). CDPC identifies activated voxels with essentially no false‐positives and proves more reliable than ICA, which is troubled by a number of false positives comparable to that of true positives. The reliability of the method is demonstrated on real fMRI data from a simple motor task, containing brief iterations of the same movement. The clusters identified are found in regions expected to be involved in the task, and repeat synchronously with the paradigm. The methodology proposed is especially suitable for the study of short‐time brain dynamics and single trial experiments, where the event or task of interest cannot be repeated for the same subject, as happens, for instance, in problem‐solving, learning and decision‐making. A GUI implementation of our method is available for download at https://github.com/micheleallegra/CDPC. Hum Brain Mapp 38:1421–1437, 2017. © 2016 Wiley Periodicals, Inc.
Head and neck surgical subspecialty training in Africa: Sustainable models to improve cancer care in developing countries
Authors: Fagan Johannes J. , Zafereo Mark , Aswani Joyce , Netterville James L. , Koch Wayne 
Published: November 2016

AbstractBackgroundCancer poses a health crisis in the developing world where surgery is the mainstay of treatment for head and neck cancers. However, a shortage of surgeons with appropriate skills exists. How do we train head and neck surgeons in developing countries and avoid a brain drain? The ideal model provides appropriate affordable training leading to establishment of head and neck cancer centers that teach and train others.MethodsDifferent head and neck surgery training models are presented based on the personal experiences of the authors. Surgical exposure of head and neck fellows in Cape Town and (potentially) in Nairobi is benchmarked against programs in the United States.ResultsSurgical exposure in Cape Town is equivalent to that in the United States, but more appropriate to a developing world setting.ConclusionTraining can be achieved in a number of ways, which may be complimentary. Fellowship training is possible in developing countries. © 2016 Wiley Periodicals, Inc. Head Neck 39: 605–611, 2017
The Orange Side of Disperse Red 1: Humidity‐Driven Color Switching in Supramolecular Azo‐Polymer Materials Based on Reversible Dye Aggregation
Authors: Schoelch Simon , Vapaavuori Jaana , Rollet Frédéric‐Guillaume , Barrett Christopher J. 
Published: November 2016

Humidity detection, and the quest for low‐cost facile humidity‐sensitive indicator materials is of great interest for many fields, including semi‐conductor processing, food transport and storage, and pharmaceuticals. Ideal humidity‐detection materials for a these applications might be based on simple clear optical readout with no power supply, i.e.: a clear color change observed by the naked eye of any untrained observer, since it doesn't require any extra instrumentation or interpretation. Here, the introduction of a synthesis‐free one‐step procedure, based on physical mixing of easily available commercial materials, for producing a humidity memory material which can be easily painted onto a wide variety of surfaces and undergoes a remarkable color change (approximately 100 nm blue‐shift of λMAX) upon exposure to various thresholds of levels of ambient humidity is reported. This strong color change, easily visible to as a red‐to‐orange color switch, is locked in until inspection, but can then be restored reversibly if desired, after moderate heating. By taking advantage of spontaneously‐forming reversible ‘soft’ supramolecular bonds between a red‐colored azo dye and a host polymer matrix, a reversible dye ‘migration’ aggregation appearing orange, and dis‐aggregation back to red can be achieved, to function as the sensor.
image
Chiral Brønsted Acid‐Catalyzed Enantioselective α‐Amidoalkylation Reactions: A Joint Experimental and Predictive Study
Authors: Aranzamendi Eider , Arrasate Sonia , Sotomayor Nuria , González‐Díaz Humberto , Lete Esther 
Published: November 2016

AbstractEnamides with a free NH group have been evaluated as nucleophiles in chiral Brønsted acid‐catalyzed enantioselective α‐amidoalkylation reactions of bicyclic hydroxylactams for the generation of quaternary stereocenters. A quantitative structure–reactivity relationship (QSRR) method has been developed to find a useful tool to rationalize the enantioselectivity in this and related processes and to orient the catalyst choice. This correlative perturbation theory (PT)‐QSRR approach has been used to predict the effect of the structure of the substrate, nucleophile, and catalyst, as well as the experimental conditions, on the enantioselectivity. In this way, trends to improve the experimental results could be found without engaging in a long‐term empirical investigation.
Toxicity of Insensitive Munition (IMX) Formulations and Components
Authors: Johnson Mark S. , Eck William S. , Lent Emily M. 
Published: November 2016

AbstractNew insensitive munitions are being developed to minimize the acute hazards associated with non‐intentional detonation of warheads. Two components often used in munition formulations have limited toxicity data, i.e., 3‐nitro‐1,2,4‐triazol‐5‐one (NTO) and 2,4‐dinitroanisole (DNAN). Oral acute, subacute, and subchronic studies have recently been completed. The primary adverse effect from subchronic oral NTO exposure was hypospermia, which followed a dose‐dependent trend. Effects from DNAN exposure include reduced body weight, anemia, and neurotoxicity. Occupational exposure levels (OEL) have recently been developed for NTO and DNAN. However, other concerns regarding environmental issues have been raised. Herein we present the latest toxicity data and interpretations for NTO and DNAN as well as the third component of IMX‐101, nitroguanidine (NQ), and describe a process to assist with holistic environmental, safety, and occupational health assessment for sustained production and use.