bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structural pounding between adjacent buildings subjected to strong ground motions. Part I: The effect of different structures arrangement
Authors: Efraimiadou Sofia , Hatzigeorgiou George D. , Beskos Dimitri E. 
Published: February 2013

SUMMARYThe effect of different structures configurations on the collision between adjacent planar RC building frames subjected to strong earthquakes is examined in this paper. Two 5‐storey and two 8‐storey frames, regular or with setbacks, are combined together to produce nine different pairs of adjacent RC structures. These pairs of buildings are subjected to six strong ground motions that are absolutely compatible with the design process. Various parameters are investigated such as maximum displacements, permanent displacements, members' ductility and internal forces and interstorey drift ratios. It is concluded that the effect of collision of adjacent frames seems to be unfavourable for most of the cases and, therefore, the structural pounding phenomenon is rather detrimental than beneficial. Copyright © 2013 John Wiley & Sons, Ltd.
The effects of an environmentally relevant 58-congener polychlorinated biphenyl (PCB) mixture on cardiac development in the chick embryo
Authors: Carro Tiffany , Taneyhill Lisa A. , Ann Ottinger Mary 
Published: February 2013

Abstract

Chicken (Gallus domesticus) embryonic exposure in ovo to a 58-congener polychlorinated biphenyl (PCB) mixture resulted in teratogenic heart defects in chick embryos at critical heart developmental stages Hamburger–Hamilton (HH) stages 10, 16, and 20. The 58-congener mixture contained relative proportions of primary congeners measured in belted sandpiper (Megaceryle alcyon) and spotted sandpiper (Actitis macularia) eggs collected along the upper Hudson River, New York, USA, and chicken doses were well below observed environmental exposure levels. Embryos were injected with 0.08 µg PCBs/g egg weight and 0.50 µg PCBs/g egg weight (0.01 and 0.064 ng toxic equivalent/g, respectively) at embryonic day 0, prior to incubation. Mortality of exposed embryos was increased at all developmental stages, with a marked rise in cardiomyopathies at HH16 and HH20 (p &lt; 0.05). Heart abnormalities occurred across all treatments, including abnormal elongation and expansion of the heart tube at HH10, improper looping and orientation, indentations in the emerging ventricular wall (HH16 and HH20), and irregularities in overall heart shape (HH10, HH16, and HH20). Histology was conducted on 2 cardiac proteins critical to embryonic heart development, ventricular myosin heavy chain and titin, to investigate potential mechanistic effects of PCBs on heart development, but no difference was observed in spatiotemporal expression. Similarly, cellular apoptosis in the developing heart was not affected by exposure to the PCB mixture. Conversely, cardiomyocyte proliferation rates dramatically declined (p &lt; 0.01) at HH16 and HH20 as PCB exposure concentrations increased. Early embryonic cardiomyocyte proliferation contributes to proper formation of the morphology and overall thickness of the ventricular wall. Therefore, in ovo exposure to this 58-congener PCB mixture at critical stages adversely affects embryonic heart development. Environ Toxicol Chem 2013;32:1317–1324. © 2013 SETAC
Toxicity of ZnO nanoparticles to the copepod Acartia tonsa, exposed through a phytoplankton diet
Authors: Jarvis Tayler A. , Miller Robert J. , Lenihan Hunter S. , Bielmyer Gretchen K. 
Published: February 2013

Abstract

Zinc oxide (ZnO) nanoparticles are being increasingly utilized in a variety of products and applications and are therefore commonly discharged into aquatic environments, increasing exposure and potentially impacting aquatic organisms. Zinc oxide nanoparticles can depress growth of some marine phytoplankton, and several examples of nanoparticle trophic transfer have been documented, although not within planktonic communities. The authors test whether feeding on ZnO-exposed phytoplankton could cause toxic effects in a widespread and ecologically important marine grazer, the copepod Acartia tonsa. The authors exposed the diatom Thalassiosira weissflogii to ZnO nanoparticles for 7 d and measured growth, zinc accumulation, and zinc distribution within the algal cells to elucidate bioavailability to grazing copepods. Thalassiosira weissflogii cultured with nano-ZnO were continuously fed to A. tonsa for 7 d, and reproduction and survival were quantified. A dose-dependent growth reduction was observed in T. weissflogii exposed to nano-ZnO, with a 20% effective concentration (EC20) of 70 µg/L Zn and a lowest observed effect concentration (LOEC) of 99 µg/L Zn. Zinc accumulation in the algae occurred dose-dependently over time, with the majority of the zinc partitioning into the cell wall fraction. Feeding on ZnO-exposed diatoms led to a decrease in copepod survival and reproduction. The EC20s corresponding to the dissolved zinc concentration in the T. weissflogii exposure media were 112 µg/L (13 µg/g dry wt) and 143 µg/L (16 µg/g dry wt), and the LOECs were 168 µg/L (17 µg/g dry wt) and 263 µg/L (21 µg/g dry wt) for copepod survival and reproduction, respectively. These results provide evidence of trophic transfer of metal contaminants associated with metal oxide nanomaterials within a marine plankton community, leading to a reduction in individual demographic performance of an important coastal marine grazer. Environ Toxicol Chem 2013;32:1264–1269. © 2013 SETAC
Quantum dots exhibit less bioaccumulation than free cadmium and selenium in the earthworm Eisenia andrei
Authors: Stewart David T.R. , Noguera-Oviedo Katia , Lee Vincent , Banerjee Sarbajit , Watson David F. , Aga Diana S. 
Published: February 2013

Abstract

The present study addresses the bioaccumulation behavior of cadmium selenide quantum dots by Eisenia andrei earthworms in a terrestrial environment. Earthworms were exposed to quantum dot-treated soil for up to 4 wk and analyzed for cadmium and selenium concentration using inductively coupled plasma mass spectrometry. Results were compared with those from earthworms exposed to cadmium nitrate and selenious acid, as positive controls, and those exposed in untreated soil (negative control). Earthworms exposed to quantum dots showed significant bioaccumulation of cadmium and selenium (5.3- and 1.5-fold higher concentration over negative controls, respectively) after 4 wk. Over the same 4 wk, positive control earthworms accumulated 9.2- and 2.2-fold higher cadmium and selenium, respectively, than negative controls for a much more substantial final body burden of the 2 elements. The concentrations also increased with exposure time; cadmium concentrations increased from 3600 ± 310 ng/g to 8080 ± 660 ng/g, from 1 to 4 wk, suggesting that further bioaccumulation may take place with even longer exposure time. The molar ratio of cadmium to selenium in the quantum dot-exposed worms (6.2) is closer to the ratios seen in positive control worms (7.2) than to the pure quantum dots (1.8), which implies that quantum dots are taken up predominantly in the degraded form. The results suggest that chemical modification of quantum dots to protect them from environmental degradation could potentially reduce bioaccumulation of the nanoparticles by earthworms. Environ Toxicol Chem 2013;32:1288–1294. © 2013 SETAC
An entropy fixed cell‐centered Lagrangian scheme
Authors: Xu Xihua , Ni Guoxi , Jiang Song 
Published: February 2013

SUMMARYOn the basis of the work [P.‐H. Maire, R. Abgrall, J. Breil, J. Ovadia, SIAM J. Sci. Comput. 29 (2007), 1781–1824], we present an entropy fixed cell‐centered Lagrangian scheme for solving the Euler equations of compressible gas dynamics. The scheme uses the fully Lagrangian form of the gas dynamics equations, in which the primary variables are cell‐centered. And using the nodal solver, we obtain the nodal viscous‐velocity, viscous‐pressures, antidissipation velocity, and antidissipation pressures of each node. The final nodal velocity is computed as a weighted sum of viscous‐velocity and antidissipation velocity, so do nodal pressures, whereas these weights are calculated through the total entropy conservation for isentropic flows. Consequently, the constructed scheme is conservative in mass, momentum, and energy; preserves entropy for isentropic flows, and satisfies a local entropy inequality for nonisentropic flows. One‐ and two‐dimensional numerical examples are presented to demonstrate theoretical analysis and performance of the scheme in terms of accuracy and robustness.Copyright © 2013 John Wiley & Sons, Ltd.
Municipal Bonds and Monetary Policy: Evidence from the Fed Funds Futures Market
Authors: Rosa Carlo 
Published: February 2013

AbstractThis paper examines the impact of conventional and unconventional monetary policy on municipal bonds using a novel high‐frequency dataset. I use three proxies for monetary policy surprises: the surprise change to the current federal funds target rate, the surprise component in the Federal Open Market Committee (FOMC) balance‐of‐risk statement, and the unanticipated announcements of future large‐scale asset purchases. Estimation results show that monetary policy news have economically important and highly significant effects on municipal bond prices. Their daily responses are, however, substantially lower than the reaction of comparable Treasury notes. This work documents that market (in)efficiency, and the slow adjustment of municipal bond prices, can partially rationalize this discrepancy. © 2013 Wiley Periodicals, Inc. Jrl Fut Mark 34:434–450, 2014
The impact of stratospheric resolution on the detectability of climate change signals in the free atmosphere
Authors: Mitchell D. M. , Stott P. A. , Gray L. J. , Allen M. R. , Lott F. C. , Butchart N. , Hardiman S. C. , Osprey S. M. 
Published: February 2013

AbstractWe perform a comparison of temperature changes in the free atmosphere over the period 1961–2010 using a high‐top (lid at 84 km) and low‐top (lid at 40 km) version of the HadGEM2 atmosphere‐ocean global climate model. Model simulations of historical climate change that include key anthropogenic and natural external forcings are compared with three different radiosonde data sets. We also apply a regression‐based “optimal fingerprinting” method to determine whether model‐predicted temperature‐change signals in response to external forcing are identifiable in observations. This method employs simulations that isolate the signals associated with different sets of external forcings (well‐mixed GHGs and natural external factors). In both high‐ and low‐top models, we obtain positive detection of the signals arising from anthropogenic influences. We find statistically significant differences between the latitude‐height temperature signals simulated by the high‐ and low‐top models, particularly in the tropical lower stratosphere. The scaling factors associated with each of the separate forcings are more tightly constrained in the high‐top over the low‐top model, but otherwise are similar in nature. Finally, we show that in detecting the GHG fingerprint, it is the entire vertical temperature profile that is important, not simply the lower‐most tropospheric levels.
Optical backscattering is correlated with phytoplankton carbon across the Atlantic Ocean
Authors: Martinez‐Vicente V. , Dall'Olmo G. , Tarran G. , Boss E. , Sathyendranath S. 
Published: February 2013

AbstractPhytoplankton are an important component of the oceanic carbon cycle. Yet, due to methodological constraints, the carbon biomass of phytoplankton is poorly characterized. To address this limitation, we have explored the bio‐optical relationship between in situ measurements of the particle backscattering coefficient at 470 nm, bbp(470), and the phytoplankton carbon concentration for cells with diameter less than 20 µm (Cf). We found a significant relationship between bbp(470) and Cf for Atlantic oceanic waters with chlorophyll‐a concentrations less than 0.4 mg m−3 (or bbp(470) < 0.003 m−1). This relationship could be used to estimate Cf from data collected by in situ autonomous platforms and from remote sensing of ocean color.
Consolidation of object recognition memory requires HRI kinase‐dependent phosphorylation of eIF2α in the hippocampus
Authors: ILL‐Raga Gerard , Köhler Cristiano , Radiske Andressa , Lima Ramón H. , Rosen Mark D. , Muñoz Francisco J. , Cammarota Martín 
Published: February 2013

AbstractLocal control of protein synthesis at synapses is crucial for synaptic plasticity and memory formation. However, little is known about the signals coupling neurotransmitter release with the translational machinery during these processes. Here, we studied the involvement of heme‐regulated inhibitor (HRI) kinase, a kinase activated by nitric oxide that phosphorylates eukaryotic initiation factor 2α (eIF2α), in object recognition (OR) memory consolidation. Phosphorylated eIF2α mediates two opposing effects upon translation: translational arrest of most mRNAs and translational activation of selected mRNAs bearing specific features in their 5′untranslated regions (5′UTRs). We found that HRI kinase activation in the CA1 region of the dorsal hippocampus is necessary for retention of OR memory in rats. Accordingly, learning induced a transient increase in the phosphorylation state of eIF2α in dorsal CA1 which was abolished by the HRI kinase inhibitor N‐(2,6‐dimethylbenzyl)‐6,7‐dimethoxy‐2H‐[1]benzofuro[3,2‐c]pyrazol‐3‐amine hydrochloride (AMI). The increase in p‐eIF2α was associated with increased expression of BACE1 and activating transcription factor 4, two proteins containing eIF2α‐responsive 5′UTRs in their mRNAs that play a key role in synaptic plasticity. Our data suggests that learning promotes the transient phosphorylation of eIF2α to allow for translation of specific 5′UTR‐mRNAs through a process requiring HRI kinase activation. © 2013 Wiley Periodicals, Inc.
Ultrastructural features of corneas with pellucid marginal degeneration
Authors: Akhtar Saeed , Kirat Omar , Alkatan Hind , Shu Xinhua , Almubrad Turki 
Published: February 2013

ABSTRACTPURPOSEPellucid marginal degeneration (PMD) of the cornea is a rare ectatic disorder which typically affects the inferior or superior peripheral cornea in a crescentic fashion. We report histological and ultrastructural features of three PMD corneas. METHODS: The following three patients were diagnosed with PMD corneas: (A) one 41‐year‐old male, (B) one 56‐year‐old female, and (C) one 31‐year‐old male. The patients underwent keratoplasty and the excised corneas were processed for light and electron microscopy to study the ultrastructural features. RESULTS: Degenerated corneas were observed in the region adjacent to the limbus. In the degenerated region of the cornea, the Bowman's layer had been replaced by collagenous pannus and the anterior stroma contained degenerated collagen fibrils (CFs) with very large proteoglycans (462±420 nm2). The lamellae were fused and keratocytes appeared like fibroblast. The prelimbal region of the PMD cornea had a degenerated Bowman's layer and thin undulating lamellae in the stroma. The CFs of the Bowman's layer and the stroma were replaced by very fine microfilaments. The mean of the minimum CF diameter was 19±3 nm in London Rsin White‐embedded tissue. CONCLUSIONS: Our observations of the disorganization and degeneration of CFs suggest that PMD could be related to a disorder in the synthesis of CF. This disorder was more severe in the cornea adjacent to the limbus compared to the cornea further away from the limbus. Microsc. Res. Tech. 76:404–411, 2013. © 2013 Wiley Periodicals, Inc.
Effect of in‐office bleaching agents on the surface roughness and morphology of different dental composites: An AFM study
Authors: Varanda Eduardo , Do Prado Maíra , Simão Renata A. , Dias Katia Regina Hostílio Cervantes 
Published: February 2013

ABSTRACTThe aim of this study was to evaluate, using atomic force microscopy, the effect of two different bleaching agents on the modification of dental composites materials. This modification will be judged by analyzing the variation of surface roughness and surface morphology of two different composites: one containing nanoparticles and other consisting of microhybrid resin. The bleaching was performed by using two different concentrations of hydrogen peroxide: HP Blue (20% hydrogen peroxide) and Whiteness HP Maxx (35% hydrogen peroxide). Disks of Esthet X and Filtek™ Z350 composites were used. Atomic force microscopy was used for analyses of the same place of the sample before and after treatment. A total of 12 analyses were performed per group (n = 12). The samples were analyzed qualitatively by evaluating morphological changes in the images and quantitatively by using roughness parameters (Ra). Data were analyzed statistically using Kruskal–Wallis, Mann–Whitney, and Friedman tests (P < 0.05). Changes were observed both qualitatively and quantitatively only in the groups where Esthet X resin was used. The use of hydrogen peroxide bleaching agents caused changes only in the surface of microhybrid composites, with no changes being observed in the composite containing nanoparticles. Despite being even significant, these alterations are clinically slight and can be eliminated by polishing them. Microsc. Res. Tech. 76:481–485, 2013. © 2013 Wiley Periodicals, Inc.
How do attendings perceive housestaff autonomy? Attending experience, hospitalists, and trends over time
Authors: Martin Shannon K. , Farnan Jeanne M. , Mayo Ainoa , Vekhter Benjamin , Meltzer David O. , Arora Vineet M. 
Published: February 2013

BACKGROUNDGraduated supervision is necessary for residents to progress to independence, but it is unclear what factors influence attendings' perception of housestaff autonomy.OBJECTIVETo determine if attending characteristics and secular trends are associated with variation in attendings' perception of housestaff autonomy.DESIGNSecondary data analysis of monthly survey data collected from 2001 to 2008.SETTING/PARTICIPANTSAttending hospitalists and nonhospitalists on teaching internal medicine services at an academic tertiary care center.MEASUREMENTSAttendings' perception of intern decision making and resident autonomy.RESULTSResponse rate was 70% (514/738). Compared with early‐career attendings, experienced attendings perceived more intern involvement in decision making (odds ratio [OR]: 2.16, 95% confidence interval [CI]: 1.17‐3.97, P=0.013). Hospitalists perceived less intern involvement in decision making (OR: 0.19, 95% CI: 0.06‐0.58, P=0.004) and resident autonomy (OR: 0.27, 95% CI: 0.11‐0.66, P=0.004) compared with nonhospitalists. A significant interaction existed between hospitalists and experience; experienced hospitalists perceived more intern decision making (OR: 7.36, 95% CI: 1.86‐29.1, P=0.004) and resident autonomy (OR: 5.85, 95% CI: 1.75‐19.6, P=0.004) compared with early‐career hospitalists. With respect to secular trends, spring season of the academic year was associated with greater perception of intern decision making compared with other seasons (OR: 1.94, 95% CI: 1.18‐3.19, P=0.009). The 2003 resident duty‐hours restrictions were associated with decreased perception of intern decision making (OR: 0.51, 95% CI: 0.29‐0.87, P=0.014) and resident autonomy (OR: 0.49, 95% CI: 0.28‐0.86, P=0.012).CONCLUSIONSPerception of housestaff autonomy varies with attending characteristics and time trends. Hospitalists perceive autonomy and clinical decision making differently, depending on their attending experience. Journal of Hospital Medicine 2013;8:292–297. © 2013 Society of Hospital Medicine
Steady‐state equilibrium phase inversion recovery ON‐resonant water suppression (IRON) MR angiography in conjunction with superparamagnetic nanoparticles. A robust technique for imaging within a wide range of contrast agent dosages
Authors: Gitsioudis Gitsios , Stuber Matthias , Arend Ingolf , Thomas Moritz , Yu Jing , Hilbel Thomas , Giannitsis Evangelos , Katus Hugo A. , Korosoglou Grigorios 
Published: February 2013

PurposeTo investigate the ability of inversion recovery ON‐resonant water suppression (IRON) in conjunction with P904 (superparamagnetic nanoparticles which consisting of a maghemite core coated with a low‐molecular‐weight amino‐alcohol derivative of glucose) to perform steady‐state equilibrium phase MR angiography (MRA) over a wide dose range.Materials and MethodsExperiments were approved by the institutional animal care committee. Rabbits (n = 12) were imaged at baseline and serially after the administration of 10 incremental dosages of 0.57–5.7 mgFe/Kg P904. Conventional T1‐weighted and IRON MRA were obtained on a clinical 1.5 Tesla (T) scanner to image the thoracic and abdominal aorta, and peripheral vessels. Contrast‐to‐noise ratios (CNR) and vessel sharpness were quantified.ResultsUsing IRON MRA, CNR and vessel sharpness progressively increased with incremental dosages of the contrast agent P904, exhibiting constantly higher contrast values than T1‐weighted MRA over a very wide range of contrast agent doses (CNR of 18.8 ± 5.6 for IRON versus 11.1 ± 2.8 for T1‐weighted MRA at 1.71 mgFe/kg, P = 0.02 and 19.8 ± 5.9 for IRON versus −0.8 ± 1.4 for T1‐weighted MRA at 3.99 mgFe/kg, P = 0.0002). Similar results were obtained for vessel sharpness in peripheral vessels, (Vessel sharpness of 46.76 ± 6.48% for IRON versus 33.20 ± 3.53% for T1‐weighted MRA at 1.71 mgFe/Kg, P = 0.002, and of 48.66 ± 5.50% for IRON versus 19.00 ± 7.41% for T1‐weighted MRA at 3.99 mgFe/Kg, P = 0.003).ConclusionOur study suggests that quantitative CNR and vessel sharpness after the injection of P904 are consistently higher for IRON MRA when compared with conventional T1‐weighted MRA. These findings apply for a wide range of contrast agent dosages. J. Magn. Reson. Imaging
2013;38:836–844. © 2013 Wiley Periodicals, Inc.
Hepatic and splenic stiffness augmentation assessed with MR elastography in an in vivo porcine portal hypertension model
Authors: Yin Meng , Kolipaka Arunark , Woodrum David A. , Glaser Kevin J. , Romano Anthony J. , Manduca Armando , Talwalkar Jayant A. , Araoz Philip A. , McGee Kiaran P. , Anavekar Nandan S. , Ehman Richard L. 
Published: February 2013

PurposeTo investigate the influence of portal pressure on the shear stiffness of the liver and spleen in a well‐controlled in vivo porcine model with magnetic resonance elastography (MRE). A significant correlation between portal pressure and tissue stiffness could be used to noninvasively assess increased portal venous pressure (portal hypertension), which is a frequent clinical condition caused by cirrhosis of the liver and is responsible for the development of many lethal complications.Materials and MethodsDuring multiple intraarterial infusions of Dextran‐40 in three adult domestic pigs in vivo, 3D abdominal MRE was performed with left ventricle and portal catheters measuring blood pressure simultaneously. Least‐squares linear regressions were used to analyze the relationship between tissue stiffness and portal pressure.ResultsLiver and spleen stiffness have a dynamic component that increases significantly following an increase in portal or left ventricular pressure. Correlation coefficients with the linear regressions between stiffness and pressure exceeded 0.8 in most cases.ConclusionThe observed stiffness–pressure relationship of the liver and spleen could provide a promising noninvasive method for assessing portal pressure. Using MRE to study the tissue mechanics associated with portal pressure may provide new insights into the natural history and pathophysiology of hepatic diseases and may have significant diagnostic value in the future. J. Magn. Reson. Imaging 2013;38:809–815. © 2013 Wiley Periodicals, Inc.