bluuebunny/crossref_metadata_2025 huggingface dataset:
Light signal sending and receiving using Si light‐emitting diode
Authors: Kawakami Yohei , Okamoto Kensho
Published: February 2013

It has been thought that silicon (Si) is a material inapplicable to active optical devices such as light‐emitting diodes (LED) because of its indirect electronic band structure. However, one of the present authors (Okamoto) discovered that commercially available Si photodiodes emitted infrared light, and he developed an original and unique two‐way optical communication system in which each Si photodiode (Si‐PD) played the two roles of light‐emitting diode and light receiver. In this study, we report the observation directly infrared light emission from a PN Si‐PD and a PIN Si‐PD using an infrared camera and measurement of the emission spectra of the Si‐PDs. We succeeded in sending and receiving light signals at room temperature between two PN Si‐PDs, between two PIN Si‐PDs, and also between an Si‐PD and an InGaAs photodiode. This paper presents our novel system for sending and receiving light signals using an Si‐PD as a LED. © 2013 Wiley Periodicals, Inc. Electron Comm Jpn, 96(3): 38–44, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/ecj.11410
Signal processing using a statistical algorithm for vibration measurement with a self‐coupling effect sensor
Authors: Ueno Tatsuya , Tsuda Norio , Yamada Jun
Published: February 2013

In this paper, signal processing using a statistical algorithm for vibration measurement is reported. The algorithm uses the statistical features of the standard deviation of sinusoidal vibration and is capable of accuracy superior to the peak‐to‐peak method. Additionally, the algorithm achieves accuracy as good as or better than the FFT method with less hardware. This method gave good results in simulations and actual measurement values. The method is widely applied in self‐coupling effect sensors and other vibration sensors. © 2013 Wiley Periodicals, Inc. Electron Comm Jpn, 96(3): 9–16, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/ecj.11454.
Improvements in pulsed current sharing in driving parallel MOSFETs
Authors: Takagi Hajime , Orihara Masato , Yamada Tsutomu , Yanagidaira Takeshi
Published: February 2013

To switch high‐voltage and high‐current pulses by using MOS (Metal Oxide Semiconductor) transistors, it is necessary to distribute evenly the voltage and current to all elements connected in series and parallel. In parallel connection, the current flowing in each element is different depending on the series resistance and wiring inductance. We verified improvements in pulsed current sharing in parallel transistors which were arranged in line on a printed circuit board. Although the gate and drain wirings were different in length, the pulsed current was evenly distributed by using transmission line transformers. The dissipation in transistors was equalized and four transistors were driven simultaneously near the rated current. © 2013 Wiley Periodicals, Inc. Electron Comm Jpn, 96(3): 1–8, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/ecj.11471.
A carrier phase control suitable for conducted EMI noise reduction in a multiple‐converter system
Authors: Tamate Michio , Toba Akio , Matsumoto Yasushi , Wada Keijo , Shimizu Toshihisa
Published: February 2013

The conducted EMI noise flowing from power converters to an AC utility line is regulated by international commissions such as the International Electrotechnical Commission (IEC). Adherence to the IEC regulations requires that EMI filters should be used in power electronics equipment. This paper proposes a method for analyzing conducted EMI noise in multiple power converters connected to the same power line. In this method, the phase difference between subharmonic modulated carrier signals at each power converter is taken into account. The phase difference among the power converters determines the EMI noise level in a multiple converter system, as is evident from the analysis of the waveform of the common mode current. In addition, EMI noise suppression using carrier phase control is proposed. In order to reduce the size of the EMI filter effectively, the phase difference θ should be set to 360/nN°, where n is a high‐order harmonic component near 150 kHz and N is the number of power converters. Therefore, the conducted EMI noise can be reduced effectively with the help of the proposed phase control. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 183(3): 56–66, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.21305
Discharger using cascaded switched capacitor converters and selectable intermediate taps for electric double‐layer capacitors
Authors: Uno Masatoshi , Tanaka Koji
Published: February 2013

Electric double‐layer capacitors (EDLCs) offer several advantages over traditional batteries, such as a long cycle life, high power capability, and good low‐temperature performance. However, their major drawbacks, such as low specific energy and large voltage variation due to charge/discharge cycling, necessitate the use of high‐efficiency power conversion electronics that can be used to efficiently discharge EDLCs and thus completely utilize the precious stored energy. In this study, we propose a novel discharger for EDLCs; this discharger uses cascaded switched capacitor converters (SCCs) and selectable intermediate taps. Although the voltage conversion ratio of SCCs is fixed, the load voltage can be maintained within a desired range by the selectable intermediate taps. The circuit configuration, operating principles, and procedure for designing SCCs and selectable intermediate taps are presented. Experimental tests were performed using an EDLC module and a 200‐W prototype of the discharger. The obtained results showed that the 60‐V EDLC could be discharged to 30 V with an average efficiency of 96% when the load voltage was maintained within the range of 30 to 40 V. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 183(3): 37–45, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22281
Coupled analysis technique involving magnetic‐field‐control/circuit simulation and loss estimation for permanent magnet synchronous machine
Authors: Narita Katsuyuki , Yamada Takashi , Sakashita Yoshiyuki , Akatsu Kan
Published: February 2013

The high‐flux permanent magnet and flux‐barrier structure of permanent magnet synchronous machines (PMSMs) has strong magnetic saturation and harmonic components. When control algorithms for such machines are examined by performing control simulation, the use of the conventional motor model based on the voltage equation can cause problems. To avoid these problems, we introduce the technique of coupled analysis by magnetic field control and circuit simulation. Further, iron losses generated in the PMSMs can be estimated by the coupled analysis system. The iron losses under various driving conditions are calculated by the coupled analysis system and are compared with measured losses. The comparison shows that the coupled analysis system is suitable for accurately estimating the iron losses of a PMSM. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 183(3): 9–16, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22347
Structural pounding between adjacent buildings subjected to strong ground motions. Part II: The effect of multiple earthquakes
Authors: Efraimiadou Sofia , Hatzigeorgiou George D. , Beskos Dimitri E.
Published: February 2013

The effect of collision between adjacent reinforced concrete building frames under multiple earthquakes is investigated in this paper. The four planar frames and the nine different pairs of adjacent reinforced concrete structures of the first companion paper are also examined here, under five real seismic sequences. Such a sequence of earthquakes results in a significant damage accumulation in a structure because any rehabilitation action between any two successive seismic motions cannot be practically materialised because of lack of time. Various parameters are investigated, such as the maximum horizontal displacement of top floor, ductility of columns, permanent displacements and so on. Furthermore, four different separation gaps between the building frames are considered to determine their influence on the behaviour of these frames. It is concluded that in most of the cases, the seismic sequences appear to be detrimental in comparison with the single seismic events. Copyright © 2013 John Wiley & Sons, Ltd.
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

The 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

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 < 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 < 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

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

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

On 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

This 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
Velocity‐conductivity relations for cratonic lithosphere and their application: Example of Southern Africa
Authors: Jones Alan G. , Fishwick Stewart , Evans Rob L. , Muller Mark R. , Fullea Javier
Published: February 2013

Seismic velocity is a function of bulk vibrational properties of the media, whereas electrical resistivity is most often a function of transport properties of an interconnected minor phase. In the absence of a minor conducting phase then the two should be inter‐relatable primarily due to their sensitivity to temperature variation. We develop expressions between shear wave velocity and resistivity for varying temperature, composition, and water content based on knowledge from two kimberlite fields: Jagersfontein (Kaapvaal Craton) and Gibeon (Rehoboth Terrane). We test the expressions through comparison between a new high‐resolution regional seismic model, derived from surface wave inversion of earthquake data from Africa and the surrounding regions, and a new electrical image from magnetotelluric (MT) data recorded in SAMTEX (Southern African Magnetotelluric Experiment). The data‐defined robust linear regression between the two is found to be statistically identical to the laboratory‐defined expression for 40 wt ppm water in olivine. Cluster analysis defines five clusters that are all geographically distinct and tectonically relate to (i) fast, cold, and variably wet Kaapvaal Craton, (ii) fast and wet central Botswana, (iii) slow, warm, and wet Rehoboth Terrane, (iv) moderately fast, cold, and very dry southernmost Angola Craton, and (v) slow, warm, and somewhat dry Damara Belt. From the linear regression expression and the MT image we obtain predicted seismic velocity at 100 km and compare it with that from seismic observations. The differences between the two demonstrate that the linear relationship between Vs and resistivity is appropriate for over 80% of Southern Africa. Finally, using the regressions for varying water content, we infer water content in olivine across Southern Africa.
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

We 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

Phytoplankton 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

Local 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.
Processing and evaluation of bioactive coatings on polymeric implants
Authors: Rabiei Afsaneh , Sandukas Stefan
Published: February 2013

Polyetheretherketone (PEEK) is a high‐performance polymer with advantages over metallic biomaterials for application in spinal implants. In this study, hydroxyapatite (HA) coatings were deposited onto PEEK substrates using radio‐frequency magnetron sputtering for the purpose of improving bioactivity. An intermediate coating layer of yttria‐stabilized zirconia (YSZ) was first deposited onto the PEEK substrates to provide heat shielding during subsequent post‐deposition heat treatment to prevent degradation of PEEK substrates and coating/substrate interface. Plasma activation of the PEEK substrate surfaces before deposition resulted in a significant increase in coating adhesion strength. Post‐deposition heat treatments of microwave and hydrothermal annealing were studied with the goal of forming crystalline HA without the use of high temperatures required in conventional annealing. Microstructural and compositional analyses by scanning electron microscopy (SEM) and X‐ray diffraction revealed that the YSZ layer exhibited a crystalline structure as‐deposited, with columnar grains oriented along the growth direction, whereas the HA layer was shown to be amorphous as‐deposited. After microwave annealing, the HA coating exhibited a columnar crystalline microstructure, similar to that of the underlying YSZ crystalline layer; XRD analysis confirmed a crystalline HA phase in the coating. It is suggested that the existence of the crystalline YSZ layer aids in the formation of the HA layer upon heating, possibly lowering the activation energy for crystallization by providing nucleation sites for HA grain formation. Cell culture tests showed a significant increase in initial cell attachment and growth on the microwave‐annealed coatings, compared with uncoated PEEK and amorphous HA surfaces. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 101A: 2621–2629, 2013.
Ultrastructural features of corneas with pellucid marginal degeneration
Authors: Akhtar Saeed , Kirat Omar , Alkatan Hind , Shu Xinhua , Almubrad Turki
Published: February 2013

PURPOSE

Pellucid 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

The 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.
Frequency, magnitude, and characteristics of aeolian sediment transport: McMurdo Dry Valleys, Antarctica
Authors: Gillies John A. , Nickling William G. , Tilson Michael
Published: February 2013

Due, in part, to the challenging environment of Earth's high‐latitude regions, available information on cold climate effects on aeolian processes in these areas remains limited. Data from these areas, however, provide insight into the physics of sediment transport by wind and the controls on erosive winds in proximity to ice caps and topographic influences. This study presents a 2 year record of meteorological, saltation activity, horizontal saltation flux, and particle size distribution data from four sites in the McMurdo Dry Valleys of Antarctica, 2008 to 2010. Saltation measurements revealed daily and seasonal patterns with spring and summer sediment transport events occurring between 09:00 and 24:00 hours due to thermally generated winds. Fall and winter events occur at any time of day with the strongest associated with foehn winds. Threshold wind speed at 4.2 m in all seasons for all locations was ≈10 m s−1. Saltation occurred in the temperature range −40°C to +5°C. Westerly winds in the fall/winter and easterly winds in spring/summer are associated with the majority of transport events. The sand in transport is mainly 250 to 500 µm in diameter and poorly sorted. The integrated saltation flux varies over three orders of magnitude among the sites, with the lowest mean flux recorded in the Taylor Valley (2.9 kg m−1 day−1) and the highest in the eastern Victoria Valley (2271 kg m−1 day−1) for 24 hours of continuous saltation. The percentage of time saltation active at these locations annually is ≈2%, ≈4%, and ≈13%, respectively, for the Victoria, Taylor, and Wright Valleys.
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

BACKGROUND

Graduated supervision is necessary for residents to progress to independence, but it is unclear what factors influence attendings' perception of housestaff autonomy.

OBJECTIVE

To determine if attending characteristics and secular trends are associated with variation in attendings' perception of housestaff autonomy.

DESIGN

Secondary data analysis of monthly survey data collected from 2001 to 2008.

SETTING/PARTICIPANTS

Attending hospitalists and nonhospitalists on teaching internal medicine services at an academic tertiary care center.

MEASUREMENTS

Attendings' perception of intern decision making and resident autonomy.

RESULTS

Response 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).

CONCLUSIONS

Perception 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

Purpose

To 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 Methods

Experiments 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.

Results

Using 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).

Conclusion

Our 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

Purpose

To 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 Methods

During 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.

Results

Liver 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.

Conclusion

The 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.
Interstudy variability in cardiac magnetic resonance imaging measurements of ventricular volume, mass, and ejection fraction in repaired tetralogy of fallot: A prospective observational study
Authors: Blalock Shannon E. , Banka Puja , Geva Tal , Powell Andrew J. , Zhou Jing , Prakash Ashwin
Published: February 2013

Purpose

To assess the interstudy variability of cardiac magnetic resonance imaging (CMR) parameters of ventricular size and function in repaired tetralogy of Fallot (TOF).

Materials and Methods

Patients with TOF (n = 30, median age 23.5 years, 43% male) were enrolled prospectively. Each patient underwent two consecutive CMR examinations on the same day. Each examination was analyzed for ventricular size and function by two observers and multiple comparisons were made with assessment of agreement using Bland–Altman analysis and intraclass correlation coefficients (ICC).

Results

Agreement for most measures of ventricular size and function was high when a single observer analyzed both studies. Agreement was worse when different observers analyzed sequential studies. This effect was most prominent on measurements of right ventricular (RV) mass and there was slight improvement when mass was measured during systole. Aside from ventricular mass, agreement was similar for RV and left ventricular (LV) parameters.

Conclusion

CMR measures of ventricular size and function have acceptable repeatability across serial examinations in patients with repaired TOF. Measurements of RV mass are subject to higher variability. For most parameters, agreement limits are wider when measurements are performed by multiple operators. These results will aid in the interpretation of study‐to‐study variations in the follow‐up of individual patients and in designing future clinical trials. J. Magn. Reson. Imaging 2013;38:829–835. © 2013 Wiley Periodicals, Inc.
Wall shear stress estimated with phase contrast MRI in an in vitro and in vivo intracranial aneurysm
Authors: van Ooij Pim , Potters Wouter V. , Guédon Annetje , Schneiders Joppe J. , Marquering Henk A. , Majoie Charles B. , vanBavel Ed , Nederveen Aart J.
Published: February 2013

Purpose

To evaluate wall shear stress (WSS) estimations in an in vitro and in vivo intracranial aneurysm, WSS was estimated from phase contrast magnetic resonance imaging (PC‐MRI) and compared with computational fluid dynamics (CFD).

Materials and Methods

First, WSS was estimated using a high‐resolution in vitro PC‐MRI measurement under steady and pulsatile flow conditions and compared with CFD simulations. Second, WSS was estimated in steady PC‐MRI data acquired at different spatial resolutions. Third, WSS estimations in pulsatile in vivo data were compared with CFD. The direction and magnitude of WSS vectors were computed and compared.

Results

Quantitative agreement between PC‐MRI and CFD‐based WSS estimations was moderate for the phantom (Spearman ρ = 0.69). The WSS magnitude derived from PC‐MRI data was lower than CFD for both the in vitro and in vivo case. However, there was qualitative agreement between PC‐MRI and CFD, i.e. WSS vector direction was similar for both modalities. Circular WSS patterns were found both in vitro and in vivo for PC‐MRI and CFD. Increasing PC‐MRI resolution increased mean WSS magnitude and uncovered complex WSS patterns.

Conclusion

WSS patterns can be estimated based on PC‐MRI data in in vitro and in vivo aneurysm geometries. Similar WSS directions as CFD can be discerned. J. Magn. Reson. Imaging 2013;38:876–884. © 2013 Wiley Periodicals, Inc.
Free breathing three‐dimensional gradient echo‐sequence with radial data sampling (radial 3D‐GRE) examination of the pancreas: Comparison with standard 3D‐GRE volumetric interpolated breathhold examination (VIBE)
Authors: Bamrungchart Saraporn , Tantaway Engy M. , Midia Esin C. , Hernandes Mateus A. , Srirattanapong Saowanee , Dale Brian M. , Semelka Richard C.
Published: February 2013

Purpose

To evaluate the diagnostic performance of free breathing three‐dimensional gradient echo‐sequence with radial data sampling (radial 3D‐GRE) in MR imaging of the normal and diseased pancreas, using standard 3D‐GRE for comparison in cooperative patients, and to perform a preliminary assessment in noncooperative patients.

Materials and Methods

One hundred and eight consecutive patients underwent 1.5 Tesla MR imaging of the abdomen that included pre‐ and postcontrast free breathing radial 3D‐GRE. The sequences were evaluated by two radiologists retrospectively, independently, and blindly. The results were compared using Wilcoxon‐Mann‐Whitney test. Kappa statistics were used to measure the extent of agreement between the reviewers.

Results

The average scores indicated that the overall images quality of radial 3D‐GRE was lower than 3D‐GRE‐VIBE in both pre‐ and postcontrast study (P = 0.0172 and 0.0001), however it achieved a rating that approximated good. In all patients, radial 3D‐GRE had a mild extent of streak artifact, pulsation, susceptibility, and respiratory artifact. Radial 3D‐GRE approximated good results for pancreatic edge sharpness and pancreatic ductal clarity, and did not differ significantly between cooperative and noncooperative patients. Respiratory artifact was worse in cooperative than in noncooperative patients (P = 0.02). Demonstration of pancreatic disease was slightly inferior with radial 3D‐VIBE, but quality approximated good.

Conclusion

Free breathing radial 3D‐GRE may be applicable for pancreatic MR imaging in patients who are unable to suspend respiration. J. Magn. Reson. Imaging 2013;38:1572–1577. © 2013 Wiley Periodicals, Inc.
Evaluation of azimuthal anchoring energy for liquid crystal device equipped with color filter by means of renormalized transmission ellipsometry
Authors: Goda Kazuya , Kimura Munehiro , Akahane Tadashi
Published: February 2013

In this study, we theoretically investigated the influence of a color filter on the determination of the azimuthal anchoring energy by means of ellipsometric analysis, and the azimuthal anchoring energy of the twisted nematic (TN) liquid crystal devices (LCDs) equipped with/without a color filter was evaluated by means of renormalized transmission ellipsometry. The results indicated no influence in the obtained ellipsometric parameters, such as the phase difference and the angle of amplitude ratio, when a color filter was an isotropic medium. It was experimentally confirmed that the evaluated azimuthal anchoring energy of LCD with a color filter was almost the same as that without a color filter. From the numerical and experimental study, the possibility for the determination of the azimuthal anchoring energy for the commercial TN LCD products was demonstrated.
The syndrome of deafness‐dystonia: Clinical and genetic heterogeneity
Authors: Kojovic Maja , Pareés Isabel , Lampreia Tania , Pienczk‐Reclawowicz Karolina , Xiromerisiou Georgia , Rubio‐Agusti Ignacio , Kramberger Milica , Carecchio Miryam , Alazami Anas M. , Brancati Francesco , Slawek Jaroslaw , Pirtosek Zvezdan , Valente Enza Maria , Alkuraya Fowzan S. , Edwards Mark J. , Bhatia Kailash P.
Published: February 2013

The syndrome of deafness‐dystonia is rare and refers to the association of hearing impairment and dystonia when these are dominant features of a disease. Known genetic causes include Mohr‐Tranebjaerg syndrome, Woodhouse‐Sakati syndrome, and mitochondrial disorders, but the cause frequently remains unidentified. The aim of the current study was to better characterize etiological and clinical aspects of deafness‐dystonia syndrome. We evaluated 20 patients with deafness‐dystonia syndrome who were seen during the period between 1994 and 2011. The cause was identified in only 7 patients and included methylmalonic aciduria, meningoencephalitis, perinatal hypoxic‐ischemic injury, large genomic deletion on chromosome 7q21, translocase of inner mitochondrial membrane 8 homolog A (TIMM8A) mutation (Mohr‐Tranebjaerg syndrome), and chromosome 2 open reading frame 37 (C2orf37) mutation (Woodhouse‐Sakati syndrome). The age of onset and clinical characteristics in these patients varied, depending on the etiology. In 13 patients, the cause remained unexplained despite extensive work‐up. In the group of patients who had unknown etiology, a family history for deafness and/or dystonia was present the majority of patients, suggesting a strong genetic component. Sensory‐neural deafness always preceded dystonia. Two clinical patterns of deafness‐dystonia syndrome were observed: patients who had an onset in childhood had generalized dystonia (10 of 13 patients) with frequent bulbar involvement, whereas patients who had a dystonia onset in adulthood had segmental dystonia (3 of 13 patients) with the invariable presence of laryngeal dystonia. Deafness‐dystonia syndrome is etiologically and clinically heterogeneous, and most patients have an unknown cause. The different age at onset and variable family history suggest a heterogeneous genetic background, possibly including currently unidentified genetic conditions. © 2013 Movement Disorder Society
A weighted dual porous medium equation applied to image restoration
Authors: Li Jing , Yin Jingxue , Sun Jiebao , Guo Zhichang
Published: February 2013

In this paper, we discuss a weighted dual porous medium equation which could be applied to image restoration. After theoretical analysis based on nonlinear semigroup theory, we give experiments to show the efficiency of this novel model. Copyright © 2013 John Wiley & Sons, Ltd.