bluuebunny/crossref_metadata_2025 huggingface dataset:
Luminescent Di‐ and Polynuclear Organometallic Gold(I)–Metal (Au2, {Au2Ag}n and {Au2Cu}n) Compounds Containing Bidentate Phosphanes as Active Antimicrobial Agents
Authors: Frik Malgorzata , Jiménez Josefina , Gracia Ismael , Falvello Larry R. , Abi‐Habib Sarya , Suriel Karina , Muth Theodore R. , Contel María
Published: February 2012

The reaction of new dinuclear gold(I) organometallic complexes containing mesityl ligands and bridging bidentate phosphanes [Au2(mes)2(μ‐LL)] (LL=dppe: 1,2‐bis(diphenylphosphano)ethane 1 a, and water‐soluble dppy: 1,2‐bis(di‐3‐pyridylphosphano)ethane 1 b) with Ag+ and Cu+ lead to the formation of a family of heterometallic clusters with mesityl bridging ligands of the general formula [Au2M(μ‐mes)2(μ‐LL)][A] (M=Ag, A=ClO4−, LL=dppe 2 a, dppy 2 b; M=Ag, A=SO3CF3−, LL=dppe 3 a, dppy 3 b; M=Cu, A=PF6−, LL=dppe 4 a, dppy 4 b). The new compounds were characterized by different spectroscopic techniques and mass spectrometry The crystal structures of [Au2(mes)2(μ‐dppy)] (1 b) and [Au2Ag(μ‐mes)2(μ‐dppe)][SO3CF3] (3 a) were determined by a single‐crystal X‐ray diffraction study. 3 a in solid state is not a cyclic trinuclear Au2Ag derivative but it gives an open polymeric structure instead, with the {Au2(μ‐dppe)} fragments “linked” by {Ag(μ‐mes)2} units. The very short distances of 2.7559(6) Å (AuAg) and 2.9229(8) Å (AuAu) are indicative of gold–silver (metallophilic) and aurophilic interactions. A systematic study of their luminescence properties revealed that all compounds are brightly luminescent in solid state, at room temperature (RT) and at 77 K, or in frozen DMSO solutions with lifetimes in the microsecond range and probably due to the self‐aggregation of [Au2M(μ‐mes)2(μ‐LL)]+ units (M=Ag or Cu; LL=dppe or dppy) into an extended chain structure, through AuAu and/or AuM metallophilic interactions, as that observed for 3 a. In solid state the heterometallic Au2M complexes with dppe (2 a–4 a) show a shift of emission maxima (from ca. 430 to the range of 520‐540 nm) as compared to the parent dinuclear organometallic product 1 a while the complexes with dppy (2 b–4 b) display a more moderate shift (505 for 1 b to a max of 563 nm for 4 b). More importantly, compound [Au2Ag(μ‐mes)2(μ‐dppy)]ClO4 (2 b) resulted luminescent in diluted DMSO solution at room temperature. Previously reported compound [Au2Cl2(μ‐LL)] (LL dppy 5 b) was also studied for comparative purposes. The antimicrobial activity of 1–5 and Ag[A] (A=ClO4−, SO3CF3−) against Gram‐positive and Gram‐negative bacteria and yeast was evaluated. Most tested compounds displayed moderate to high antibacterial activity while heteronuclear Au2M derivatives with dppe (2 a–4 a) were the more active (minimum inhibitory concentration 10 to 1 μg mL−1). Compounds containing silver were ten times more active to Gram‐negative bacteria than the parent dinuclear compound 1 a or silver salts. Au2Ag compounds with dppy (2 b, 3 b) were also potent against fungi.
A Bayesian approach to mixture cure models with spatial frailties for population‐based cancer relative survival data
Authors: Yu Binbing , Tiwari Ram C.
Published: February 2012

As the treatments of cancer progress, a certain number of cancers are curable if diagnosed early. In population‐based cancer survival studies, cure is said to occur when mortality rate of the cancer patients returns to the same level as that expected for the general cancer‐free population. The estimates of cure fraction are of interest to both cancer patients and health policy makers. Mixture cure models have been widely used because the model is easy to interpret by separating the patients into two distinct groups. Usually parametric models are assumed for the latent distribution for the uncured patients. The estimation of cure fraction from the mixture cure model may be sensitive to misspecification of latent distribution. We propose a Bayesian approach to mixture cure model for population‐based cancer survival data, which can be extended to county‐level cancer survival data. Instead of modeling the latent distribution by a fixed parametric distribution, we use a finite mixture of the union of the lognormal, loglogistic, and Weibull distributions. The parameters are estimated using the Markov chain Monte Carlo method. Simulation study shows that the Bayesian method using a finite mixture latent distribution provides robust inference of parameter estimates. The proposed Bayesian method is applied to relative survival data for colon cancer patients from the Surveillance, Epidemiology, and End Results (SEER) Program to estimate the cure fractions.The Canadian Journal of Statistics40: 40–54; 2012 © 2012 Statistical Society of Canada
A resampling approach to estimate variance components of multilevel models
Authors: Wang Zilin , Thompson Mary E.
Published: February 2012

In a multilevel model for complex survey data, the weight‐inflated estimators of variance components can be biased. We propose a resampling method to correct this bias. The performance of the bias corrected estimators is studied through simulations using populations generated from a simple random effects model. The simulations show that, without lowering the precision, the proposed procedure can reduce the bias of the estimators, especially for designs that are both informative and have small cluster sizes. Application of these resampling procedures to data from an artificial workplace survey provides further evidence for the empirical value of this method. The Canadian Journal of Statistics 40: 150–171; 2012 © 2012 Statistical Society of Canada
Approximate jackknife empirical likelihood method for estimating equations
Authors: Peng Liang
Published: February 2012

It is known that the profile empirical likelihood method based on estimating equations is computationally intensive when the number of nuisance parameters is large. Recently, Li, Peng, & Qi (2011) proposed a jackknife empirical likelihood method for constructing confidence regions for the parameters of interest by estimating the nuisance parameters separately. However, when the estimators for the nuisance parameters have no explicit formula, the computation of the jackknife empirical likelihood method is still intensive. In this paper, an approximate jackknife empirical likelihood method is proposed to reduce the computation in the jackknife empirical likelihood method when the nuisance parameters cannot be estimated explicitly. A simulation study confirms the advantage of the new method. The Canadian Journal of Statistics 40: 110–123; 2012 © 2012 Statistical Society of Canada
A stochastic graph process for epidemic modelling
Authors: Hosseinkashi Yasaman , Chenouri Shojaeddin , Small Christopher G. , Deardon Rob
Published: February 2012

A stochastic graph process with a Markov property is introduced to model the flow of an infectious disease over a known contact network. The model provides a probability distribution over unobserved infectious pathways. The basic reproductive number in compartmental models is generalized to a dynamic reproductive number based on the sequence of outdegrees in the graph process. The cumulative resistance and threat associated with each individual is also measured based on the cumulative indegree and outdegree of the graph process. The model is applied to the outbreak data from the 2001 foot‐and‐mouth (FMD) outbreak in the United Kingdom. The Canadian Journal of Statistics 40: 55–67; 2012 © 2012 Statistical Society of Canada
Randomized broadcasting in wireless mobile sensor networks
Authors: Abdallah Nesrine Ouled , Kacem Hatem Hadj , Mosbah Mohamed , Zemmari Akka
Published: February 2012

Wireless sensor networks are a new generation of networks that need specific models and algorithms. We are interested specifically in mobile wireless sensor networks that are considered as anonymous asynchronous distributed mobile systems. As broadcast is one of the most important applications for such networks, and as it depends on the communication model, we tried to find the most suitable one to make a distributed broadcast algorithm. We adopted the population protocols, the Angluin's model of pairwise interactions of anonymous finite‐state agents, to broadcast an information. We tried to modify this model to avoid the information duplication and then calculated the complexity of the algorithm. Then, we extended the model with the rendezvous one that made the stabilization of the algorithm faster. The implementation, the simulation, and the validation of these algorithms and results have been done with Visidia. Copyright © 2012 John Wiley & Sons, Ltd.
Stakeholder Expectation of Corporate Social Responsibility Practices: A Study on Local and Multinational Corporations in Kazakhstan
Authors: Mahmood Monowar , Humphrey Janet
Published: February 2012

Assuming differences among the stakeholders, the study investigated stakeholders' expectations of different aspects of corporate social responsibility (CSR) practices in Kazakhstan. As a transition economy, both internal stakeholders and the government still place more emphasis on economic and legal responsibilities for the sustainability of business organizations. On the other hand, civil society members and non‐governmental organizations (NGOs) argue that business organizations need to focus more on ethical and discretionary responsibilities in Kazakhstan. The findings of the study will help both local business organizations and multinational corporations (MNCs) to understand stakeholders' expectations and to modify CSR activities in the right direction in the context of emerging economies. The policy implications of the study are also discussed. Copyright © 2012 John Wiley & Sons, Ltd and ERP Environment
MCS9.7 Enhancer activity is highly, but not completely, associated with expression of Irf6 and p63
Authors: Fakhouri Walid D. , Rhea Lindsey , Du Tianli , Sweezer Eileen , Morrison Harris , Fitzpatrick David , Yang Baoli , Dunnwald Martine , Schutte Brian C.
Published: February 2012

MCS9.7‐lacZ expression in whole mount staining. Bgal activity was detected in transient (Rahimov et al. [2008] Nat Gen 40:1341–1347), and in stable transgenic murine embryos at E11.5. Optical tomography (OPT) movies showing the Bgal activity of stable transgenic embryo in 2‐D. Counterstaining was done using green pseudocolor and red represent Bgal expression. From Fakhouri et al., Developmental Dynamics 241:340–349, 2012.
Concurrent habitat and life history influences on effective/census population size ratios in stream‐dwelling trout
Authors: Belmar‐Lucero Sebastian , Wood Jacquelyn L. A. , Scott Sherylyne , Harbicht Andrew B. , Hutchings Jeffrey A. , Fraser Dylan J.
Published: February 2012

Lower effective sizes (Ne) than census sizes (N) are routinely documented in natural populations, but knowledge of how multiple factors interact to lower Ne/N ratios is often limited. We show how combined habitat and life‐history influences drive a 2.4‐ to 6.1‐fold difference in Ne/N ratios between two pristine brook trout (Salvelinus fontinalis) populations occupying streams separated by only 750 m. Local habitat features, particularly drainage area and stream depth, govern trout biomass produced in each stream. They also generate higher trout densities in the shallower stream by favoring smaller body size and earlier age‐at‐maturity. The combination of higher densities and reduced breeding site availability in the shallower stream likely leads to more competition among breeding trout, which results in greater variance in individual reproductive success and a greater reduction in Ne relative to N. A similar disparity between juvenile or adult densities and breeding habitat availability is reported for other species and hence may also result in divergent Ne/N ratios elsewhere. These divergent Ne/N ratios between adjacent populations are also an instructive reminder for species conservation programs that genetic and demographic parameters may differ dramatically within species.
The Utilization of Performance Information: the Dutch Network Ecological Monitoring
Authors: de Kool Dennis
Published: February 2012

New Public Management has been a catalyst for monitoring activities in the public sector. Although monitoring of policy processes is quite prevalent, the utilization of monitoring data remains underexplored. This article analyses the utilization of information generated by the Dutch Network Ecological Monitoring (NEM), by first looking at its characteristics. We then distinguish between theoretical approaches to utilizing monitoring data and the critical factors for utilizing monitoring suggested by these approaches. Finally, the NEM is used to draw empirical and theoretical conclusions with respect to the utilization of information from performance monitoring. Copyright © 2012 John Wiley & Sons, Ltd and ERP Environment.
Heterometallic, Hybrid, Heavy Main‐Group Iodometallates Containing Lanthanide Complexes: Template Synthesis, Structures, Thermal, Optical, Luminescent and Magnetic Properties
Authors: Mishra Shashank , Jeanneau Erwann , Iasco Olga , Ledoux Gilles , Luneau Dominique , Daniele Stéphane
Published: February 2012

Using [Ln(L)8]3+ [Ln = Tb, Y; L = dimethyl sulfoxide (DMSO), N,N‐dimethylformamide (DMF)] cations as templating reagents, the syntheses and crystal structures of the following new metal organic–inorganic hybrid complexes based on either discrete clusters or 1D chains of an iodoplumbate or‐bismuthate moiety are reported: [Tb(DMSO)8]2[(DMSO)2Pb5I16] (1), [Tb(DMF)8][Pb3I9]1∞·DMF (2) and [Ln(DMF)8][Bi2I9] [Ln = Y (3), Tb (4)]. These derivatives were characterized by thermogravimetric analysis (TGA), diffuse‐reflectance spectroscopy, luminescence spectroscopy and magnetic studies. TGA studies show that the thermal stability of these complexes decreases in the order 2 > 3 ≈ 4 > 1. An optical band‐gap in the range 1.90–2.15 eV in the diffuse‐reflectance spectra of 1–4 indicate their potential use as semiconductors, 3 and 4 being the most promising because of their low band gap values. Compared to the precursors [Tb(DMSO)8]I3 and [Tb(DMF)8]I3, the high energy transitions in the excitation spectra of 1, 2 and 4 are quenched by a process that is best attributed to the autoionization of the carriers in the material. The temperature dependence of the magnetic susceptibilities of 1, 2 and 4 was reproduced well by a Curie–Weiss plot at 2–300 K.
α‐Polymethine‐Substituted Boron Dipyrromethenes – BODIPY‐Based NIR Cyanine‐Like Dyes
Authors: Shandura Mykola P. , Yakubovskyi Viktor P. , Gerasov Andriy O. , Kachkovsky Olexiy D. , Poronik Yevgen M. , Kovtun Yuriy P.
Published: February 2012

A series of dyes bearing polymethine chromophore units in boron dipyrromethene (BODIPY) α‐positions were prepared by condensation of 3,5‐dimethyl boron dipyrromethene with various hemicyanines. One or two methyl groups of the starting material can react, yielding the corresponding mono‐ and disubstituted derivatives. The deeply coloured monosubstituted dyes belong to the family of merocyanine dyes and exhibit spectral properties and chemical behaviour similar to those of meso‐analogues. On the other hand, disubstituted dyes show more complex absorption spectra compared to their monosubstituted counterparts, and their absorption maxima are redshifted (up to 970 nm, the most redshifted absorption known among borondipyrromethene derivatives). Spectral methods and quantum‐chemical calculations suggest evolution of the long‐wavelength electronic transition from dipyrromethene type into polymethine on changing the character of the peripheral chromophore system. The nature of highest electronic transitions has been analyzed.
TMDS as a Dual‐Purpose Reductant in the Regioselective Ring Cleavage of Hexopyranosyl Acetals to Ethers
Authors: Zhang Yin‐Jie , Dayoub Wissam , Chen Guo‐Rong , Lemaire Marc
Published: February 2012

1,1,3,3‐Tetramethyldisiloxane (TMDS) has been developed as an excellent dual‐purpose reductant for the highly regioselective ring cleavage of various hexopyranosyl 4,6‐O‐acetals with Cu(OTf)2 or AlCl3 to afford the corresponding primary and secondary ethers. Its application to the concise synthesis of carbohydrate‐based surfactants is highlighted.
Competitive CE‐UV binding tests for selective recognition of bisphenol A by molecularly imprinted polymer particles
Authors: Alsudir Samar , Iqbal Zafar , Lai Edward P. C.
Published: February 2012

Capillary electrophoresis with ultraviolet detection (CE‐UV) was used to perform competitive binding tests to demonstrate the selective recognition of bisphenol A (BPA) by molecularly imprinted polymer (MIP) particles. Cross‐linking polymerization of methacrylic acid (MAA) and ethylene glycol dimethacrylate (EGDMA) in the presence of BPA yielded MIP particles with an average diameter of 164 ± 15 nm. Their ability to recognize BPA in the presence of nonionic, anionic, and cationic water contaminants was investigated. Binding efficiency was rapidly determined, after sequential injection of particles first and compounds next into the fused‐silica capillary provided a short overlapping time during their electrophoretic migrations. The MIP particles exhibited high‐binding efficiency (99 ± 1%) for BPA. Neither diclofenac nor metformin affected BPA binding, and 2‐hydroxy‐4‐methoxybenzophenone was even displaced from the particles by BPA. These results verified the high selectivity of MIP toward its target compound.
Promotional effect of 1‐butyl‐3‐methylimidazolium chloride ionic liquid on the enzymatic finishing of wool
Authors: Jiugang Yuan , Qiang Wang , Ping Wang , Li Cui , Xuerong Fan
Published: February 2012

To improve the effects of protease finishing on wool, 1‐butyl‐3‐methylimidazolium chloride ionic liquid was employed as a pretreatment reagent. It was found that ionic liquid pretreatment significantly changed the wool surface characteristics. The Allwördern reaction showed that the epicuticle layer was damaged by the ionic liquid, and X‐ray photoelectron spectroscopy analysis further demonstrated that the surface elemental composition was significantly changed. Ionic liquid pretreatment remarkably improved the accessibility of protease to the wool and thus accelerated the hydrolysis rate of keratin. The properties of wool fabric after combined processing were also changed. Dyeability results showed that the color depth was increased but the wet rubbing and washing fastness of wool fabrics showed a decreased half grade. The wettability results demonstrate that the contact angle was further reduced after the comprehensive treatment because of the exposure of more proteins under the fatty‐acid layer. In addition, the shrink proofing of wool fabric was also enhanced after combined processing. In summary, ionic liquid modification presents a promising pretreatment method for protease processing of wool.
Endocrine disrupting, mutagenic, and teratogenic effects of upper Danube River sediments using effect-directed analysis
Authors: Higley Eric , Grund Stefanie , Jones Paul D. , Schulze Tobias , Seiler Thomas-B. , Varel Urte Lübcke-von , Brack Werner , Wölz Jan , Zielke Hanno , Giesy John P. , Hollert Henner , Hecker Markus
Published: February 2012

Effect-directed analysis (EDA) can be useful in identifying and evaluating potential toxic chemicals in matrixes. Previous investigations of extracts of sediments from the upper Danube River in Germany revealed acute nonspecific and mechanism-specific toxicity as determined by several bioassays. In the present study, EDA was used to further characterize these sediments and identify groups of potentially toxic chemicals. Four extracts of sediments were subjected to a novel fractionation scheme coupled with identification of chemicals to characterize their ability to disrupt steroidogenesis or cause mutagenic and/or teratogenic effects. All four whole extracts of sediment caused significant alteration of steroidogenesis and were mutagenic as well as teratogenic. The whole extracts of sediments were separated into 18 fractions and these fractions were then subjected to the same bioassays as the whole extracts. Fractions 7 to 15 of all four extracts were consistently more potent in both the Ames fluctuation and H295R assays. Much of this toxicity could be attributed to polycyclic aromatic hydrocarbons, sterols, and in fraction 7-naphthoic acids. Because the fraction containing polychlorinated biphenyls, polychlorodibenzodioxin/furan, dichlorodiphenyltrichloroethane, and several organophosphates did not cause any observable effects on hormone production or a mutagenic response, or were not detected in any of the samples, these compounds could be eliminated as causative agents for the observed effects. These results demonstrate the value of using EDA, which uses multiple bioassays and new fractionation techniques to assess toxicity. Furthermore, to our knowledge this is the first study using the recently developed H295R assay within EDA strategies. Environ. Toxicol. Chem. 2012; 31: 1053–1062. © 2012 SETAC
Outage analysis of dual‐hop Alamouti transmission with channel estimation error
Authors: Xu Kun , Yi Xiaoxin , Gao Yuanyuan , Zang Guozhen
Published: February 2012

In this paper, we investigate the outage probability performance of dual‐hop Alamouti transmission with channel estimation error in Rayleigh fading channels. The cumulative density function‐based method is adopted to obtain the outage probability expression in closed‐form. Power allocation between the source and relay is also studied. Furthermore, asymptotic analysis is conducted to shed light on the diversity order. Finally, simulation results are presented to verify the analysis. Copyright © 2012 John Wiley & Sons, Ltd.
Cone calorimeter evaluation of two flame retardant cotton fabrics
Authors: White Robert H. , Nam Sunghyun , Parikh Dharnidhar V.
Published: February 2012

Unbleached (gray) cotton needle‐punched nonwoven (NW) fabrics with 12.5% polypropylene scrim were treated with two phosphate–nitrogen‐based flame retardant (FR) formulations, Southern Regional Research Center (SRRC)‐1 and SRRC‐2. The SRRC‐1 formulation contains diammonium phosphate as the FR chemical along with urea and dimethyloldihydroxyethyleneurea. Because a trace amount of formaldehyde was still expected to be released from SRRC‐1‐treated FR cotton under high heat, it was preferable to eliminate the dimethyloldihydroxyethyleneurea, leading to the revised formulation SRRC‐2. It has a higher content of diammonium phosphate and did not use the polyethylene emulsion that was in SRRC‐1. Both formulations were of low cost as they were developed at SRRC using industrial grade chemicals. The fabrics were evaluated with a cone calorimeter using three heat flux levels, 20, 30, and 50 kW/m2. On the basis of the overall cone calorimeter results for heat released and ignition times, FR NW fabrics that were treated with SRRC‐2 were found to be slightly superior in flammability properties to those treated with the earlier SRRC‐1 formulation, but the differences were statistically insignificant. Both preparations were much less flammable than the untreated control cotton NW fabrics. Compared with the untreated NW fabrics, the FR fabrics had higher visible smoke production. Copyright © 2012 John Wiley & Sons, Ltd.
Numerical simulation of orbitally shaken viscous fluids with free surface
Authors: Discacciati Marco , Hacker David , Quarteroni Alfio , Quinodoz Samuel , Tissot Stéphanie , Wurm Florian M.
Published: February 2012

Orbitally shaken bioreactors are an emerging alternative to stirred‐tank bioreactors for large‐scale mammalian cell culture, but their fluid dynamics is still not well defined. Among the theoretical and practical issues that remain to be resolved, the characterization of the liquid free surface during orbital shaking remains a major challenge because it is an essential aspect of gas transfer and mixing in these reactors. To simulate the fluid behavior and the free surface shape, we developed a numerical method based on the finite element framework. We found that the large density ratio between the liquid and the gas phases induced unphysical results for the free surface shape. We therefore devised a new pressure correction scheme to deal with large density ratios.

The simulations operated with this new scheme gave values of wave amplitude similar to the ones measured experimentally. These simulations were used to calculate the shear stress and to study the mixing principle in orbitally shaken bioreactors. Copyright © 2012 John Wiley & Sons, Ltd.
Geometric computation of human gyrification indexes from magnetic resonance images
Authors: Su Shu , White Tonya , Schmidt Marcus , Kao Chiu‐Yen , Sapiro Guillermo
Published: February 2012

Human brains are highly convoluted surfaces with multiple folds. To characterize the complexity of these folds and their relationship with neurological and psychiatric conditions, different techniques have been developed to quantify the folding patterns, also known as the surface complexity or gyrification of the brain. In this study, the authors propose a new geometric approach to measure the gyrification of human brains from magnetic resonance images. This approach is based on intrinsic 3D measurements that relate the local brain surface area to the corresponding area of a tightly wrapped sheet. The authors also present an adaptation of this technique in which the geodesic depth is incorporated into the gyrification computation. These gyrification measures are efficiently and accurately computed by solving geometric partial differential equations. The presentation of the geometric framework is complemented with experimental results for brain complexity in typically developing children and adolescents. Using this novel approach, the authors provide evidence for a gradual decrease in brain surface complexity throughout childhood and adolescence. These developmental differences occur earlier in the occipital lobe and move anterior as children progress into young adulthood. Hum Brain Mapp, 2013. © 2012 Wiley Periodicals, Inc.
Periods of rest in fMRI contain individual spontaneous events which are related to slowly fluctuating spontaneous activity
Authors: Petridou Natalia , Gaudes César Caballero , Dryden Ian L. , Francis Susan T. , Gowland Penny A.
Published: February 2012

fMRI studies of brain activity at rest study slow (<0.1 Hz) intrinsic fluctuations in the blood‐oxygenation‐level‐dependent (BOLD) signal that are observed in a temporal scale of several minutes. The origin of these fluctuations is not clear but has previously been associated with slow changes in rhythmic neuronal activity resulting from changes in cortical excitability or neuronal synchronization. In this work, we show that individual spontaneous BOLD events occur during rest, in addition to slow fluctuations. Individual spontaneous BOLD events were identified by deconvolving the hemodynamic impulse response function for each time point in the fMRI time series, thus requiring no information on timing or a‐priori spatial information of events. The patterns of activation detected were related to the motor, visual, default‐mode, and dorsal attention networks. The correspondence between spontaneous events and slow fluctuations in these networks was assessed using a sliding window, seed‐correlation analysis, where seed regions were selected based on the individual spontaneous event BOLD activity maps. We showed that the correlation varied considerably over time, peaking at the time of spontaneous events in these networks. By regressing spontaneous events out of the fMRI signal, we showed that both the correlation strength and the power in spectral frequencies <0.1 Hz decreased, indicating that spontaneous activation events contribute to low‐frequency fluctuations observed in resting state networks with fMRI. This work provides new insights into the origin of signals detected in fMRI studies of functional connectivity. Hum Brain Mapp, 2013. © 2012 Wiley Periodicals, Inc.
Emotional brain rhythms and their impairment in post‐traumatic patients
Authors: Cohen Jonathan E. , Shalev Hadar , Admon Roee , Hefetz Shy , Gasho Christopher J. , Shachar Lavi J. , Shelef Ilan , Hendler Talma , Friedman Alon
Published: February 2012

Patients with post‐traumatic stress disorder (PTSD) suffer from a failure of cognitive control over emotional distracters. The physiological substrates of cognitive‐emotional interactions and their breakdown in disease are, however, unknown. Here, we studied brain activity in PTSD patients and healthy controls in response to emotion‐provoking pictures using electroencephalography and functional magnetic resonance imaging (fMRI). We demonstrate that in healthy individuals, emotion‐induced frontal theta rhythm modulates activity in the beta rhythm mainly in sensory‐motor regions. In contrast, in PTSD patients, beta activity is elevated irrespective of emotion, and is not modulated by frontal theta activity in response to negative emotion. EEG source localization and fMRI findings suggest that theta activity is localized to the prefrontal and anterior cingulate cortices while beta activity is localized to sensory‐motor regions. We further found that beta activity in sensory‐motor regions is related to the emotion‐induced slowing of the motor response in healthy controls while the excess frontal theta activity in PTSD is related to the intensity of negative emotional experience. These findings reveal for the first time the importance of brain electrical oscillations and coherence in emotional top‐down modulation and point to specific failure of these mechanisms in PTSD. Hum Brain Mapp, 2013. © 2012 Wiley Periodicals, Inc.
The dimensionality of between‐person differences in white matter microstructure in old age
Authors: Lövdén Martin , Laukka Erika Jonsson , Rieckmann Anna , Kalpouzos Grégoria , Li Tie‐Qiang , Jonsson Tomas , Wahlund Lars‐Olof , Fratiglioni Laura , Bäckman Lars
Published: February 2012

Between‐person differences in white matter microstructure may partly generalize across the brain and partly play out differently for distinct tracts. We used diffusion‐tensor imaging and structural equation modeling to investigate this issue in a sample of 260 adults aged 60–87 years. Mean fractional anisotropy and mean diffusivity of seven white matter tracts in each hemisphere were quantified. Results showed good fit of a model positing that individual differences in white matter microstructure are structured according to tracts. A general factor, although accounting for variance in the measures, did not adequately represent the individual differences. This indicates the presence of a substantial amount of tract‐specific individual differences in white matter microstructure. In addition, individual differences are to a varying degree shared between tracts, indicating that general factors also affect white matter microstructure. Age‐related differences in white matter microstructure were present for all tracts. Correlations among tract factors did not generally increase as a function of age, suggesting that aging is not a process with homogenous effects on white matter microstructure across the brain. These findings highlight the need for future research to examine whether relations between white matter microstructure and diverse outcomes are specific or general. Hum Brain Mapp, 2013. © 2012 Wiley Periodicals, Inc.
Cortical plasticity is preserved in nondemented older individuals with severe ischemic small vessel disease
Authors: List Jonathan , Duning Thomas , Kürten Julia , Deppe Michael , Wilbers Eike , Flöel Agnes
Published: February 2012

Ischemic small vessel disease (SVD) is a common finding on routine scans in older people, but cognitive sequelae vary considerably. To improve understanding of mechanisms underlying decline or preservation of cognitive function in this condition, we assessed cognition and cortical plasticity in 20 elderly subjects with severe SVD and 20 age‐matched controls without SVD, as rated on conventional MRI. Cognitive status was determined with a neuropsychological test battery, cortical plasticity induced with a paired associative stimulation protocol. Microstructural white matter changes were further analyzed for fractional anisotrophy using diffusion tensor imaging. We found that cortical plasticity as well as memory functions were preserved in severe SVD, while executive functions showed trendwise or significant decreases. Within the SVD group, lower white matter integrity in parahippocampal regions and posterior parts of the corpus callosum was associated with larger cortical plasticity, an association not seen for prefrontal white matter tracts. Enhanced cortical plasticity in subjects with lower white matter integrity in memory‐relevant areas might thus indicate a compensatory mechanism to counteract memory decline in severe SVD. Hum Brain Mapp, 2013. © 2012 Wiley Periodicals, Inc.
HOW HAVE AGRICULTURAL POLICIES INFLUENCED CALORIC CONSUMPTION IN THE UNITED STATES?
Authors: Rickard Bradley J. , Okrent Abigail M. , Alston Julian M.
Published: February 2012

Many commentators have speculated that agricultural policies have contributed to increased obesity rates in the United States, yet such claims are often made without any analysis of the complex links between real‐world farm commodity support programs, prices and consumption of foods, and caloric intake. This article carefully studies the effects of US agricultural policies on prices and quantities of 10 agricultural commodities and nine food categories in the United States over time. Using a detailed multimarket model, we simulate the counterfactual removal of measures of support applied to US agricultural commodities in 1992, 1997, and 2002 and quantify the effects on US food consumption and caloric intake. To parameterize the simulations, we calculate three alternative measures of consumer support (the implicit consumer subsidy from policies that support producers) for the 10 agricultural commodities using information about government expenditures on agricultural commodities from various sources. Our results indicate that—holding all other policies constant—removing US subsidies on grains and oilseeds in the three periods would have caused caloric consumption to decrease minimally whereas removal of all US agricultural policies (including barriers against imports of sugar and dairy products) would have caused total caloric intake to increase. Our results also indicate that the influence of agricultural policies on caloric intake has diminished over time. Copyright © 2012 John Wiley & Sons, Ltd.
Analysis of the BOLD characteristics in pass‐band bSSFP fMRI
Authors: Kim Taek Soo , Lee Jongho , Lee Jin Hyung , Glover Gary H. , Pauly John M.
Published: February 2012

Balanced steady‐state free precession (bSSFP) has been proposed as an alternative method to acquire the blood oxygenation level dependent contrast. Particularly, pass‐band bSSFP functional magnetic resonance imaging (fMRI) is believed to utilize the T2 sensitivity of bSSFP in a relatively wide and flat off‐resonance frequency band of the bSSFP profile. The method has a potential to provide higher signal to noise ratio (SNR) efficiency with reduced imaging artifacts compared to conventional approaches. Previous experimental results suggested that the level of the functional contrast and its characteristics are significantly influenced by the sequence parameters. However, few of these contrast characteristics have been investigated systematically. In this study, a computer simulation was performed to investigate the sources of functional contrast and the influence of scan parameters on the functional contrast to elucidate the contrast characteristics of pass‐band bSSFP fMRI. Experiments were performed to validate the simulation results. © 2012 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 22, 23–32, 2012
Positron emission tomography in neurological and psychiatric disorders
Authors: Newberg Andrew , Monti Daniel , Moss Aleeze , Alavi Abass
Published: February 2012

Positron emission tomography (PET) has been widely used in the study of neurological and psychiatric disorders. It has been used most extensively in research to determine pathophysiology as well as prognostic and diagnostic information and response to various interventions in different disorders. PET imaging has also been used in the clinical setting, although its use has been primarily to help differentiate or diagnose specific disorders. With the continued development of a large array of radiopharmaceuticals that can evaluate all the components of different neurotransmitter systems (such as serotonin and dopamine), PET imaging will continue to play a key role in research and clinical applications for neurological and psychiatric disorders. © 2012 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 22, 2–17, 2012
MRtrix: Diffusion tractography in crossing fiber regions
Authors: Tournier J‐Donald , Calamante Fernando , Connelly Alan
Published: February 2012

In recent years, diffusion‐weighted magnetic resonance imaging has attracted considerable attention due to its unique potential to delineate the white matter pathways of the brain. However, methodologies currently available and in common use among neuroscientists and clinicians are typically based on the diffusion tensor model, which has comprehensively been shown to be inadequate to characterize diffusion in brain white matter. This is due to the fact that it is only capable of resolving a single fiber orientation per voxel, causing incorrect fiber orientations, and hence pathways, to be estimated through these voxels. Given that the proportion of affected voxels has been recently estimated at 90%, this is a serious limitation. Furthermore, most implementations use simple “deterministic” streamlines tracking algorithms, which have now been superseded by “probabilistic” approaches. In this study, we present a robust set of tools to perform tractography, using fiber orientations estimated using the validated constrained spherical deconvolution method, coupled with a probabilistic streamlines tracking algorithm. This methodology is shown to provide superior delineations of a number of known white matter tracts, in a manner robust to crossing fiber effects. These tools have been compiled into a software package, called MRtrix, which has been made freely available for use by the scientific community. © 2012 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 22, 53–66, 2012
A k‐space sharing 3D GRASE pseudocontinuous ASL method for whole‐brain resting‐state functional connectivity
Authors: Liang Xiaoyun , Tournier Jacques‐Donald , Masterton Richard , Connelly Alan , Calamante Fernando
Published: February 2012

Magnetic resonance imaging (MRI) investigations of resting‐state functional connectivity (RSFC) typically use blood oxygen level‐dependent (BOLD)‐weighted imaging because of its ability to provide whole‐brain coverage and high temporal resolution. Single‐shot 3D gradient‐ and spin‐echo (GRASE) arterial spin labeling (ASL) offers a number of potential advantages for RSFC measurements, such as a more direct quantitative correlate of neural activity and lower variability across subjects; however, current sequences are usually not suitable for whole‐brain acquisitions because of T2 decay during the long echo train. In this study, we proposed a k‐space sharing 3D GRASE ASL sequence to achieve whole‐brain coverage, applied it to measure RSFC on a group of healthy subjects, and compared it with BOLD data. Similar RSFC networks were estimated using both techniques, providing corroboration of the capability of our method for RSFC analysis. Furthermore, ASL data enable calculation of mean cerebral blood flow (CBF) values within the RSFC networks, thus assigning them biologically meaningful values. The inherently quantitative nature of CBF measurements should provide a more stable and interpretable biomarker in comparison to BOLD and may, therefore, be particularly useful for applications such as longitudinal studies of RSFC. © 2012 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 22, 37–43, 2012
Microvascular functional MR angiography with ultra‐high‐field 7 t MRI: Comparison with BOLD fMRI
Authors: Cho Zang‐Hee , Kang Chang‐Ki , Park Chan‐A , Hong Suk‐Min , Kim Sang‐Hoon , Oh Seung‐Taek , Kim Young‐Bo
Published: February 2012

Microvascular functional MR angiography using ultra‐high‐field 7 T MRI was used to visualize specific arterial changes in response to stimulation, and the results were compared to conventional blood oxygen level‐dependent (BOLD) functional magnetic resonance imaging (fMRI). To demonstrate the potential of this new method, we conducted a visual experiment with 14 healthy subjects using optimized acquisition parameters and a dedicated radio frequency coil for 7 T MRI. The signal intensity change in the blood vessels supplying to the visual cortex, specifically the calcarine arteries, was clearly observed during stimulation. The signal changes were increased gradually up to as high as 12% as the vessel segments approach to the visual cortex where neuronal activity was believed to be occurred. The activation foci were not identical to those obtained by conventional fMRI, as expected, but they were closely related and confined to the visual cortical areas, when compared to fMRI responses. Therefore, fMRA technique using ultra‐high‐field 7 T MRI could provide the direct observation of microvascular changes in the arterial input vessels in relation to neuronal activity. © 2012 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 22, 18–22, 2012
Slow delayed rectifying potassium current (IKs) – analysis of the in vitro inhibition data and predictive model development
Authors: Polak Sebastian , Wiśniowska Barbara , Glinka Anna , Fijorek Kamil , Mendyk Aleksander
Published: February 2012

The excitable cell membranes contain ion channels that allow the ions passage through the specific pores via a passive process. Assessment of the inhibition of the IKr (hERG) current is considered to be the main target during the drug development process, although there are other ionic currents for which drug‐triggered modification can either potentiate or mask hERG channel blockade. Information describing the results of in vitro studies investigating the chemical–IKs current interactions has been developed in the current study. Based on the publicly available data sources, 145 records were collected. The final list of publications consists of 64 positions and refers to 106 different molecules connected with IKs current inhibition, with at least one IC50 value measured. Ultimately, 98 of the IC50 values expressed as absolute values were gathered. For 36 records the IC50 was expressed as a relative value. For the 11 remaining records, the inhibition was not clearly expressed. Based on the collected data the predictive models for the IC50 estimation were developed with the use of various algorithms. The extended Quantitative Structure‐Activity Relationships (QSAR) methodology was applied and the in vitro research settings were included as independent variables, apart from the physico‐chemical descriptors calculated with the use of the Marvin Calculator Plugins. The root mean squared error and normalized root mean squared error values for the best model (an expert system based on two independent artificial neural networks) were 0.86 and 14.04%, respectively. The model was further built into the ToxComp system, the ToxIVIVE tool specialized for cardiotoxicity assessment of drugs. Copyright © 2012 John Wiley & Sons, Ltd.
Austenitic and duplex stainless steels in simulated physiological solution characterized by electrochemical and X‐ray photoelectron spectroscopy studies
Authors: Kocijan Aleksandra , Conradi Marjetka , Schön Peter M.
Published: February 2012

A study of oxide layers grown on 2205 duplex stainless steel (DSS) and AISI 316L austenitic stainless steel in simulated physiological solution is presented here in order to establish the possibility of replacement of AISI 316 L with 2205 DSS in biomedical applications. The results of the potentiodynamic measurements show that the extent of the passive range significantly increased for DSS 2205 compared to AISI 316L stainless steel. Cyclic voltammetry was used to investigate electrochemical processes taking place on the steel surfaces. Oxide layers formed by electrochemical oxidation at different oxidation potentials were studied by X‐ray photoelectron spectroscopy, and their compositions were analyzed as a function of depth. The main constituents on both the investigated materials were Cr‐ and Fe‐oxides. Atomic force microscopy topography studies revealed the higher corrosion resistance of the DSS 2205 compared to the AISI 316L under the chosen experimental conditions. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2012.
Novel microwave synthesis of amorphous calcium phosphate nanospheres
Authors: Zhou Huan , Bhaduri Sarit
Published: February 2012

Amorphous calcium phosphate (ACP) is an important precursor phase in tissue mineralization. It shows high solubility and excellent remineralization ability. Commercially viable techniques for producing ACP are high‐cost/low‐efficiency process. This article describes a novel microwave (MW)‐assisted ACP synthesis route as an alternative to current ACP synthesis methods. An important feature of the process is the use of supersaturated biomimetic fluids (SBFs), which are based on Kokubo‐like simulated body fluids. However, our present compositions are substantially different in that they no longer simulate the body fluid compositions. The effects of solution composition and processing parameters were studied. The mechanism of ACP synthesis under MW irradiation process is also discussed. The as‐synthesized ACP nanospheres were characterized and showed good reactivity and biocompatibility. These as‐synthesized nanoparticles can be potential candidates for biomedical applications and remineralization mechanism study. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2012.
Identifying FGA peptides as nasopharyngeal carcinoma‐associated biomarkers by magnetic beads
Authors: Tao Ya‐Lan , Li Yan , Gao Jin , Liu Zhi‐Gang , Tu Zi‐Wei , Li Guo , Xu Bing‐Qing , Niu Dao‐Li , Jiang Chang‐Bin , Yi Wei , Li Zhi‐Qiang , Li Jing , Wang Yi‐Ming , Cheng Zhi‐Bin , Liu Qiao‐Dan , Bai Li , Zhang Chun , Zhang Jing‐Yu , Zeng Mu‐Sheng , Xia Yun‐Fei
Published: February 2012

Early diagnosis and treatment is known to improve prognosis for nasopharyngeal carcinoma (NPC). The study determined the specific peptide profiles by comparing the serum differences between NPC patients and healthy controls, and provided the basis for the diagnostic model and identification of specific biomarkers of NPC. Matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOF‐MS) can be used to detect the molecular mass of peptides. Mass spectra of peptides were generated after extracting and purification of 40 NPC samples in the training set, 21 in the single center validation set and 99 in the multicenter validation set using weak cationic‐exchanger magnetic beads. The spectra were analyzed statistically using FlexAnalysis™ and ClinProt™ bioinformatics software. The four most significant peaks were selected out to train a genetic algorithm model to diagnose NPC. The diagnostic sensitivity and specificity were 100% and 100% in the training set, 90.5% and 88.9% in the single center validation set, 91.9% and 83.3% in the multicenter validation set, and the false positive rate (FPR) and false negative rate (FNR) were obviously lower in the NPC group (FPR, 16.7%; FNR, 8.1%) than in the other cancer group (FPR, 39%; FNR, 61%), respectively. So, the diagnostic model including four peptides can be suitable for NPC but not for other cancers. FGA peptide fragments identified may serve as tumor‐associated biomarkers for NPC. J. Cell. Biochem. 113: 2268–2278, 2012. © 2012 Wiley Periodicals, Inc.