bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reduced cadmium accumulation and toxicity in Daphnia magna under carbon nanotube exposure
Authors: Liu Jie , Wang Wen-Xiong 
Published: June 2015

Abstract

With increasing application and commercial production, carbon nanotubes (CNTs) will inevitably be released into aquatic environments and affect the transport and toxicity of toxic metals in ecosystems. The present study examined how CNTs affected the biokinetics and toxicity of a toxic metal, cadmium (Cd), in the freshwater zooplankton Daphnia magna. The authors quantified the dissolved uptake and the 50% lethal concentration (LC50, 48 h and 72 h) of Cd in daphnids in the presence of functionalized multiwalled nanotubes (F-CNTs) with different lengths (10–30 µm vs 0.5–2 µm) and concentrations (4 mg/L and 8 mg/L). Compared with the control treatment without CNTs, both CNTs slowed down the accumulation rate of Cd in D. magna over 8 h of exposure and further reduced the accumulation thereafter. Mechanisms for the reduced Cd uptake were mainly related to the influences of CNTs on the physiological activity of daphnids. The LC50 of D. magna in the presence of Cd and shorter CNTs was almost the same as that of the control group without CNTs. However, the LC50 of the groups with normal CNTs was significantly higher than that of the control group (i.e., F-CNTs decreased Cd toxicity significantly). Meanwhile, CNTs also decreased the tolerance of D. magna to Cd. The present study suggests that different physical properties of CNTs, such as length, need to be considered in the environmental risk assessment of CNTs. Environ Toxicol Chem 2015;34:2824–2832. © 2015 SETAC
Toxicokinetics and toxicodynamics of differently coated silver nanoparticles and silver nitrate in Enchytraeus crypticus upon aqueous exposure in an inert sand medium
Authors: Topuz Emel , van Gestel Cornelis A.M. 
Published: June 2015

Abstract

The aim of the present study was to evaluate the effect of silver nanoparticles (AgNPs) on Enchytraeus crypticus, applying a combined toxicokinetics and toxicodynamics approach to understand the relationship between survival and the development of internal Ag concentrations in the animals over time. Toxicity tests were conducted in medium composed of well-defined aqueous solutions added to inert quartz sand to avoid the complexity of soil conditions. Citrate-coated AgNPs (AgNP-Cit) and polyvinylpyrrolidone-coated AgNPs (AgNP-PVP) were tested and compared with silver nitrate (AgNO3), which was used as a positive control for Ag ion effects. The median lethal concentration (LC50) values based on Ag concentrations in the solution phase of the test medium decreased over time and reached steady state after 7 d, with AgNO3 and AgNP-PVP being more toxic than AgNP-Cit. Slow dissolution may explain the low uptake kinetics and lower toxicity of AgNP-Cit compared with the other 2 Ag forms. The LC50 values based on internal Ag concentrations in the animals were almost stable over time, highlighting the importance of integrating toxicokinetics and toxicodynamics and relating survival with internal Ag concentrations. Neither survival-based elimination rates nor internal LC50s in the organisms showed any significant evidence of nano-specific effects for both AgNPs, although they suggested some uptake of particulate Ag for AgNP-Cit. The authors conclude that the toxicity of both types of AgNP probably is mainly attributable to the release of Ag ions. Environ Toxicol Chem 2015;34:2816–2823. © 2015 SETAC
Dynamically adaptive tree grid modeling for simulation and visualization of rainwater overland flow
Authors: Busaman Anurak , Mekchay Khamron , Siripant Suchada , Chuai‐Aree Somporn 
Published: June 2015

SummaryModeling and visualization of a rainwater overland flow is an important tool for a risk assessment, preparation, evacuation planning, and real‐time forecasting of flood warning. The objective of this research is to develop a numerical software to visualize the rainwater overland flow based on a finite volume method for shallow water equations and in combination with the dynamically adaptive tree grid technique and the dynamic domain‐defining method. The obtained simulations for several experiments were tested and compared with results in literature, both theoretical and experimental results. The comparisons with non‐adaptive grids show that the developed algorithm for simulation is very efficient and has a potential for practical usages, in terms of computational times and accuracy. Copyright © 2015 John Wiley & Sons, Ltd.
Investigation on Electrocatalytic Activity and Stability of Pt/C Catalyst Prepared by Facile Solvothermal Synthesis for Direct Methanol Fuel Cell
Authors: Zhang L. M. , Wang Z. B. , Zhang J. J. , Sui X. L. , Zhao L. , Han J. C. 
Published: June 2015

AbstractPt nanoparticles supported on Vulcan XC‐72 carbon black have been synthesized by a facile solvothermal method. The obtained Pt/C catalysts are characterized by X‐ray diffraction (XRD), energy dispersive X‐ray analysis (EDAX), and transmission electron microscopy (TEM) analysis to identify Pt mean size and Pt content. The results of electrochemical measurements demonstrate that the Pt/C catalyst prepared at the reaction temperature of 140 °C and the reaction time of 2 h shows the biggest initial electrochemical area with an initial electrochemically active specific surface area (ESA) of 70.6 m2gPt−1, the highest electrocatalytic stability with an ESA loss of 48.7% after 1,000 CV cycles, and the best electrocatalytic activity and stability toward methanol oxidation reaction (MOR) with a specific activity of 0.6 mA cm−2 and a retention rate (the ratio of the final current density to the maximum current density) after 3,600 s of 42.8%. Moreover, the electrochemical performance of homemade Pt/C catalyst is superior to that of commercial Pt/C catalyst, suggesting that the solvothermal synthesis is a promising method for preparing Pt based catalyst.
Magmatic source and metamorphic grade of metavolcanic rocks from the Granjeno Schist: was northeastern Mexico a part of Pangaea?
Authors: Torres Sánchez Sonia Alejandra , Augustsson Carita , Barboza Gudiño José Rafael , Jenchen Uwe , Ramírez Fernández Juan Alonso , Abratis Michael , Scherstén Anders 
Published: June 2015

AbstractThe geochemistry of the metavolcanic rocks from the Granjeno Schist in northeastern Mexico indicates an origin in different tectonic environments: mid‐ocean ridge and ocean island. High ratios of Hf/Th and Th/Nb (4.4–14 and 0.08–0.15), low ratios of LaN/YbN and LaN/SmN (0.74–1.7 and 0.60–1.4) and depleted LREE patterns in metabasalt display mid‐ocean ridge characteristics. In contrast, the pattern of trace‐element ratios and REEs in metabasalt and metapillow lava 60 km to the west indicates a magma source with ocean‐island basalt characteristics. Both areas were metamorphosed during the Late Carboniferous (300 ± 4 Ma). Estimated metamorphic conditions deduced from white mica and chlorite compositions, distinguish greenschist facies (350 °C and 4 kbar) for the mid‐ocean ridge basalt, and prehnite–pumpellyite facies (250 °C and 2.5 kbar) for the ocean‐island‐type basalt. This metamorphism took place at an active continental margin during Pennsylvanian time. Our new tectonic model, which differs from earlier models, suggests that the origin of the Granjeno Schist is related to a subduction zone located at the western margin of Pangaea, active after Laurentia–Gondwana collision. Copyright © 2015 John Wiley & Sons, Ltd.
Time‐resolved detection of stimulus/task‐related networks, via clustering of transient intersubject synchronization
Authors: Bordier Cécile , Macaluso Emiliano 
Published: June 2015

AbstractSeveral methods are available for the identification of functional networks of brain areas using functional magnetic resonance imaging (fMRI) time‐series. These typically assume a fixed relationship between the signal of the areas belonging to the same network during the entire time‐series (e.g., positive correlation between the areas belonging to the same network), or require a priori information about when this relationship may change (task‐dependent changes of connectivity). We present a fully data‐driven method that identifies transient network configurations that are triggered by the external input and that, therefore, include only regions involved in stimulus/task processing. Intersubject synchronization with short sliding time‐windows was used to identify if/when any area showed stimulus/task‐related responses. Next, a first clustering step grouped together areas that became engaged concurrently and repetitively during the time‐series (stimulus/task‐related networks). Finally, for each network, a second clustering step grouped together all the time‐windows with the same BOLD signal. The final output consists of a set of network configurations that show stimulus/task‐related activity at specific time‐points during the fMRI time‐series. We label these configurations: “brain modes” (bModes). The method was validated using simulated datasets and a real fMRI experiment with multiple tasks and conditions. Future applications include the investigation of brain functions using complex and naturalistic stimuli.Hum Brain Mapp 36:3404–3425, 2015. ©2015 The Authors Human Brain Mapping Published by Wiley Periodicals, Inc.
Functional connectivity associated with hand shape generation: Imitating novel hand postures and pantomiming tool grips challenge different nodes of a shared neural network
Authors: Vingerhoets Guy , Clauwaert Amanda 
Published: June 2015

AbstractClinical research suggests that imitating meaningless hand postures and pantomiming tool‐related hand shapes rely on different neuroanatomical substrates. We investigated the BOLD responses to different tasks of hand posture generation in 14 right handed volunteers. Conjunction and contrast analyses were applied to select regions that were either common or sensitive to imitation and/or pantomime tasks. The selection included bilateral areas of medial and lateral extrastriate cortex, superior and inferior regions of the lateral and medial parietal lobe, primary motor and somatosensory cortex, and left dorsolateral prefrontal, and ventral and dorsal premotor cortices. Functional connectivity analysis revealed that during hand shape generation the BOLD‐response of every region correlated significantly with every other area regardless of the hand posture task performed, although some regions were more involved in some hand postures tasks than others. Based on between‐task differences in functional connectivity we predict that imitation of novel hand postures would suffer most from left superior parietal disruption and that pantomiming hand postures for tools would be impaired following left frontal damage, whereas both tasks would be sensitive to inferior parietal dysfunction. We also unveiled that posterior temporal cortex is committed to pantomiming tool grips, but that the involvement of this region to the execution of hand postures in general appears limited. We conclude that the generation of hand postures is subserved by a highly interconnected task‐general neural network. Depending on task requirements some nodes/connections will be more engaged than others and these task‐sensitive findings are in general agreement with recent lesion studies. Hum Brain Mapp 36:3426–3440, 2015. © 2015 Wiley Periodicals, Inc.
Persistency and flexibility of complex brain networks underlie dual‐task interference
Authors: Alavash Mohsen , Hilgetag Claus C. , Thiel Christiane M. , Gießing Carsten 
Published: June 2015

AbstractPrevious studies on multitasking suggest that performance decline during concurrent task processing arises from interfering brain modules. Here, we used graph‐theoretical network analysis to define functional brain modules and relate the modular organization of complex brain networks to behavioral dual‐task costs. Based on resting‐state and task fMRI we explored two organizational aspects potentially associated with behavioral interference when human subjects performed a visuospatial and speech task simultaneously: the topological overlap between persistent single‐task modules, and the flexibility of single‐task modules in adaptation to the dual‐task condition. Participants showed a significant decline in visuospatial accuracy in the dual‐task compared with single visuospatial task. Global analysis of topological similarity between modules revealed that the overlap between single‐task modules significantly correlated with the decline in visuospatial accuracy. Subjects with larger overlap between single‐task modules showed higher behavioral interference. Furthermore, lower flexible reconfiguration of single‐task modules in adaptation to the dual‐task condition significantly correlated with larger decline in visuospatial accuracy. Subjects with lower modular flexibility showed higher behavioral interference. At the regional level, higher overlap between single‐task modules and less modular flexibility in the somatomotor cortex positively correlated with the decline in visuospatial accuracy. Additionally, higher modular flexibility in cingulate and frontal control areas and lower flexibility in right‐lateralized nodes comprising the middle occipital and superior temporal gyri supported dual‐tasking. Our results suggest that persistency and flexibility of brain modules are important determinants of dual‐task costs. We conclude that efficient dual‐tasking benefits from a specific balance between flexibility and rigidity of functional brain modules. Hum Brain Mapp 36:3542–3562, 2015. © 2015 Wiley Periodicals, Inc.
Wavelet‐based regularity analysis reveals recurrent spatiotemporal behavior in resting‐state fMRI
Authors: Smith Robert X. , Jann Kay , Ances Beau , Wang Danny J.J. 
Published: June 2015

AbstractOne of the major findings from multimodal neuroimaging studies in the past decade is that the human brain is anatomically and functionally organized into large‐scale networks. In resting state fMRI (rs‐fMRI), spatial patterns emerge when temporal correlations between various brain regions are tallied, evidencing networks of ongoing intercortical cooperation. However, the dynamic structure governing the brain's spontaneous activity is far less understood due to the short and noisy nature of the rs‐fMRI signal. Here, we develop a wavelet‐based regularity analysis based on noise estimation capabilities of the wavelet transform to measure recurrent temporal pattern stability within the rs‐fMRI signal across multiple temporal scales. The method consists of performing a stationary wavelet transform to preserve signal structure, followed by construction of “lagged” subsequences to adjust for correlated features, and finally the calculation of sample entropy across wavelet scales based on an “objective” estimate of noise level at each scale. We found that the brain's default mode network (DMN) areas manifest a higher level of irregularity in rs‐fMRI time series than rest of the brain. In 25 aged subjects with mild cognitive impairment and 25 matched healthy controls, wavelet‐based regularity analysis showed improved sensitivity in detecting changes in the regularity of rs‐fMRI signals between the two groups within the DMN and executive control networks, compared with standard multiscale entropy analysis. Wavelet‐based regularity analysis based on noise estimation capabilities of the wavelet transform is a promising technique to characterize the dynamic structure of rs‐fMRI as well as other biological signals. Hum Brain Mapp 36:3603–3620, 2015. © 2015 Wiley Periodicals, Inc.
Reduced cerebellar gray matter is a neural signature of physical frailty
Authors: Chen Wei‐Ta , Chou Kun‐Hsien , Liu Li‐Kuo , Lee Pei‐Lin , Lee Wei‐Ju , Chen Liang‐Kung , Wang Pei‐Ning , Lin Ching‐Po 
Published: June 2015

AbstractPhysical frailty has been recognized as a clinical syndrome resulting from declines in various physiological systems; however, the role of the central nervous system in the pathophysiology of frailty remains unclear. The I‐Lan Longitudinal Aging Study randomly sampled community‐dwelling people aged 50 or older for a brain magnetic resonance imaging study. All participants were assessed for frailty status (robust, prefrail, and frail) based on the presence of five frailty components: slow walking speed, muscle weakness, low physical activity, exhaustion and weight loss (Fried criteria). Gray matter volume (GMV) changes associated with frailty status and individual frailty components were examined. Overall, 456 participants (64.0 ± 8.5 years, 47.6% women) were included in this study. The prefrail (n = 178, 39.0%) and frail (n = 19, 4.2%) subjects were grouped for analysis. The prefrail–frail group showed reduced GMV, compared to the robust group (n = 259, 56.8%), in the cerebellum, hippocampi, middle frontal gyri, and several other cerebral regions (corrected P < 0.05). Each frailty component was associated with GMV changes in functionally related brain areas. Hierarchical cluster analysis categorized these components into three subsets. Motor‐related components, including weakness, low activity, and slowness, comprised one subset with a common cerebellar involvement. Exhaustion and weight loss were the other two subsets without cerebellar changes. To conclude, physical frailty is associated with a decreased reserve in specific brain regions, especially cerebellum. Further longitudinal studies are needed to explore if the cerebellum‐ and noncerebellum‐based frailty components reflect a distinctive future risk for developing frailty. Hum Brain Mapp 36:3666–3676, 2015. © 2015 Wiley Periodicals, Inc.
Effect of in‐painting on cortical thickness measurements in multiple sclerosis: A large cohort study
Authors: Govindarajan Koushik A. , Datta Sushmita , Hasan Khader M. , Choi Sangbum , Rahbar Mohammad H , Cofield Stacey S. , Cutter Gary R. , Lublin Fred D. , Wolinsky Jerry S. , Narayana Ponnada A. ,   MRI Analysis Center at Houston, The CombiRx Investigators Group
Published: June 2015

AbstractA comprehensive analysis of the effect of lesion in‐painting on the estimation of cortical thickness using magnetic resonance imaging was performed on a large cohort of 918 relapsing‐remitting multiple sclerosis patients who participated in a phase III multicenter clinical trial. An automatic lesion in‐painting algorithm was developed and implemented. Cortical thickness was measured using the FreeSurfer pipeline with and without in‐painting. The effect of in‐painting was evaluated using FreeSurfer's paired analysis pipeline. Multivariate regression analysis was also performed with field strength and lesion load as additional factors. Overall, the estimated cortical thickness was different with in‐painting than without. The effect of in‐painting was observed to be region dependent, more significant in the left hemisphere compared to the right, was more prominent at 1.5 T relative to 3 T, and was greater at higher lesion volumes. Our results show that even for data acquired at 1.5 T in patients with high lesion load, the mean cortical thickness difference with and without in‐painting is ∼2%. Based on these results, it appears that in‐painting has only a small effect on the estimated regional and global cortical thickness. Hum Brain Mapp 36:3749–3760, 2015. © 2015 Wiley Periodicals, Inc.
Neuroanatomical profiles of alexithymia dimensions and subtypes
Authors: Goerlich‐Dobre Katharina Sophia , Votinov Mikhail , Habel Ute , Pripfl Juergen , Lamm Claus 
Published: June 2015

AbstractAlexithymia, a major risk factor for a range of psychiatric and neurological disorders, has been recognized to comprise two dimensions, a cognitive dimension (difficulties identifying, analyzing, and verbalizing feelings) and an affective one (difficulties emotionalizing and fantasizing). Based on these dimensions, the existence of four distinct alexithymia subtypes has been proposed, but never empirically tested. In this study, 125 participants were assigned to four groups corresponding to the proposed alexithymia subtypes: Type I (impairment on both dimensions), Type II (impairment on the cognitive, but not the affective dimension), Type III (impairment on the affective, but not the cognitive dimension), and Lexithymics (no impairment on either dimension). By means of voxel‐based morphometry, associations of the alexithymia dimensions and subtypes with gray and white matter volumes were analyzed. Type I and Type II alexithymia were characterized by gray matter volume reductions in the left amygdala and the thalamus. The cognitive dimension was further linked to volume reductions in the right amygdala, left posterior insula, precuneus, caudate, hippocampus, and parahippocampus. Type III alexithymia was marked by volume reduction in the MCC only, and the affective dimension was further characterized by larger sgACC volume. Moreover, individuals with the intermediate alexithymia Types II and III showed gray matter volume reductions in distinct regions, and had larger corpus callosum volumes compared to Lexithymics. These results substantiate the notion of a differential impact of the cognitive and affective alexithymia dimensions on brain morphology and provide evidence for separable neuroanatomical representations of the different alexithymia subtypes. Hum Brain Mapp 36:3805–3818, 2015. © 2015 Wiley Periodicals, Inc.
Breaking The Link Between Legal Access To Alcohol And Motor Vehicle Accidents: Evidence From New South Wales
Authors: Lindo Jason M. , Siminski Peter , Yerokhin Oleg 
Published: June 2015

AbstractA large literature has documented significant public health benefits associated with the minimum legal drinking age in the USA, particularly because of the resulting effects on motor vehicle accidents. These benefits form the primary basis for continued efforts to restrict youth access to alcohol. It is important to keep in mind that policymakers have a wide variety of alcohol‐control options available to them, and understanding how these policies may complement or substitute for one another can improve policy making moving forward. Towards this end, we propose that investigating the causal effects of the minimum legal drinking age in New South Wales, Australia, provides a particularly informative case study, because Australian states are among the world leaders in their efforts against drunk driving. Using an age‐based regression discontinuity design applied to restricted‐use data from several sources, we find no evidence that legal access to alcohol has effects on motor vehicle accidents of any type in New South Wales, despite having large effects on drinking and on hospitalizations due to alcohol abuse. Copyright © 2015 John Wiley & Sons, Ltd.
Does Experience Rating Improve Obstetric Practices? Evidence from Italy
Authors: Amaral‐Garcia Sofia , Bertoli Paola , Grembi Veronica 
Published: June 2015

SummaryUsing inpatient discharge records from the Italian region of Piedmont, we estimate the impact of an increase in malpractice pressure brought about by experience‐rated liability insurance on obstetric practices. Our identification strategy exploits the exogenous location of public hospitals in court districts with and without schedules for noneconomic damages. We perform difference‐in‐differences analysis on the entire sample and on a subsample which only considers the nearest hospitals in the neighborhood of court district boundaries. We find that the increase in medical malpractice pressure is associated with a decrease in the probability of performing a C‐section from 2.3 to 3.7 percentage points (7–11.6%) with no consequences for medical complications or neonatal outcomes. The impact can be explained by a reduction in the discretion of obstetric decision‐making rather than by patient cream skimming. Copyright © 2015 John Wiley & Sons, Ltd.