bluuebunny/crossref_metadata_2025 huggingface dataset:
Accuracy of equilibrium magnetization mapping in sliced two‐dimensional spoiled gradient‐recalled echo pulse sequence with variable flip angle
Authors: Kuribayashi Hideto , Sekino Masaki , Minowa Takuya , Maitani Yoshie , Ohsaki Hiroyuki , Tsushima Shohji , Hirai Shuichiro , Ueda Masayuki , Katayama Yasuo
Published: February 2013

Purpose

To evaluate the accuracy of an equilibrium magnetization (M0) map obtained using a two‐dimensional (2D) spoiled gradient‐recalled echo (SPGR) pulse sequence with variable flip angle (VFA).

Materials and Methods

Single‐slice 2D SPGR images of 4% agar gel phantoms with different gadolinium‐diethylene triamine pentaacetic acid (Gd‐DTPA) concentrations (0–1 mM) were obtained with a VFA (2–30°). The 2D SPGR‐VFA data were acquired with different repetition times (TRs; 7.8–117.2 ms), Gaussian and sinc RF pulses, and different field strengths (4.7, 7, and 9.4 Tesla). M0 and T1 maps were calculated from the 2D SPGR‐VFA data. M0 and T1 values were compared with those calculated from free‐relaxed 2D gradient‐recalled echo (GRE) images and inversion recovery‐prepared 2D SPGR images. The M0 and T1 slice profiles were also investigated.

Results

Consistent M0 values were obtained, regardless of the different Gd concentrations, TRs, and pulse sequences. The M0 slice profiles calculated from the sliced SPGR‐VFA data quantitatively reproduced those calculated from the free‐relaxed sliced GRE. In contrast, the T1 values calculated from the 2D SPGR‐VFA data were underestimated at a high Gd concentration, short TR, and Gaussian RF pulse.

Conclusion

M0 values calculated from 2D SPGR‐VFA images are highly quantitative. J. Magn. Reson. Imaging 2013;38:1245–1250. © 2013 Wiley Periodicals, Inc.
Tumor blood flow from arterial spin labeling perfusion MRI: A key parameter in distinguishing high‐grade gliomas from primary cerebral lymphomas, and in predicting genetic biomarkers in high‐grade gliomas
Authors: Yoo Roh‐Eul , Choi Seung Hong , Cho Hye Rim , Kim Tae Min , Lee Se‐Hoon , Park Chul‐Kee , Park Sung‐Hye , Kim Il Han , Yun Tae Jin , Kim Ji‐Hoon , Sohn Chul‐Ho , Han Moon Hee , Chang Kee Hyun
Published: February 2013

Purpose

To evaluate the usefulness of pseudo‐continuous arterial spin labeling (pCASL) imaging in differentiating high‐grade gliomas from lymphomas and in noninvasively predicting genetic biomarkers in high‐grade gliomas.

Materials and Methods

Twelve glioblastoma multiforme (GBM), 3 anaplastic astrocytoma (AA), 5 recurred GBM, and 9 lymphoma patients underwent conventional MR and pCASL imaging. On pCASL perfusion map, mean absolute tumor blood flow (mTBF) was calculated from five regions of interest (ROIs) within the enhancing portion of the tumor. Relative TBF (rTBF = mTBF/mBFgm × 100) was also calculated. mTBF and rTBF of high‐grade gliomas and lymphomas were compared using unpaired Student's t‐test and receiver operating characteristic (ROC) analysis. Additionally, the association of TBF and six immunohistochemically confirmed genetic biomarkers was analyzed by Pearson correlation analysis in the group of high‐grade gliomas.

Results

Both mTBF and rTBF of the high‐grade gliomas were significantly higher than those of the lymphomas: 92.1 ± 34.7 versus 53.6 ± 30.5 mL/min/100 mg (P = 0.008) and 182.3 ± 69.5 versus 92.5 ± 44.9 (P = 0.002), respectively. Only epidermal growth factor receptor (EGFR) expression status showed a significant positive correlation with mTBF(P = 0.015) and rTBF(P = 0.007).

Conclusion

pCASL imaging may facilitate differentiation of high‐grade gliomas from lymphomas and prediction of EGFR expression status in high‐grade gliomas. J. Magn. Reson. Imaging 2013;38:852–860. © 2013 Wiley Periodicals, Inc.
MR imaging quantitative analysis of fetal chiari II malformations and associated open neural tube defects: Balanced SSFP versus half‐fourier RARE and interobserver reliability
Authors: Abele Travis A. , Lee Stacy L. , Twickler Diane M.
Published: February 2013

Purpose

To evaluate bSSFP (balanced steady state free precession) and half‐Fourier RARE (rapid acceleration with relaxation enhancement) MRI sequences in their ability to demonstrate fetal anatomic landmarks, quantify the degree of cerebellar herniation in Chiari II malformations and level and length of the associated open neural tube defects, as well as evaluate interobserver reliability of these measurements.

Materials and Methods

Two independent observers retrospectively reviewed MRIs of 37 fetuses with Chiari II malformations and associated open neural tube defects (mean gestational age: 27 weeks 2 days). Comparison of bSSFP and RARE included: (i) Ability to confidently identify anatomic landmarks of the posterior fossa and spine; (ii) Measurements of the foramen magnum, cerebellar tonsillar herniation length, intervertebral disc space level of tonsillar herniation, open neural tube defect length, and disc space start and end level of the open neural tube defect; (iii) Observed conspicuity of anatomic landmarks.

Results

There was no significant difference in assessment of cerebellar tonsillar herniation or open neural tube defect level between bSSFP and RARE for either observer. Intervertebral discs were more conspicuous on bSSFP while cerebellar tonsils were more conspicuous on RARE (P < 0.05). Interobserver reliability was strong for both sequences in assessing the foramen magnum (r = 0.95, 0.94), tonsillar herniation length (r = 0.93, 0.95), and open neural tube defect length (r = 0.97, 0.96).

Conclusion

Despite improved conspicuity of the intervertebral discs with bSSFP and cerebellar tonsils with RARE, there is no significant difference in measurement of hindbrain herniation or open neural tube defect level; interobserver reliability is excellent for both sequences. J. Magn. Reson. Imaging 2013;38:786–793. © 2013 Wiley Periodicals, Inc.
Effects of perfusion on diffusion changes in human brain tumors
Authors: Cohen Alexander D. , LaViolette Peter S. , Prah Melissa , Connelly Jennifer , Malkin Mark G. , Rand Scott D. , Mueller Wade M. , Schmainda Kathleen M.
Published: February 2013

Purpose

To characterize the influence of perfusion on the measurement of diffusion changes over time when ADC is computed using standard two‐point methods.

Materials and Methods

Functional diffusion maps (FDMs), which depict changes in diffusion over time, were compared with rCBV changes in patients with brain tumors. The FDMs were created by coregistering and subtracting ADC maps from two time points and categorizing voxels where ADC significantly increased (iADC), decreased (dADC), or did not change (ncADC). Traditional FDMs (tFDMs) were computed using b = 0,1000 s/mm2. Flow‐compensated FDMs (fcFDMs) were calculated using b = 500,1000 s/mm2. Perfusion's influence on FDMs was determined by evaluating changes in rCBV in areas where the ADC change significantly differed between the two FDMs.

Results

The mean ΔrCBV in voxels that changed from iADC (dADC) on the tFDM to ncADC on the fcFDM was significantly greater (less) than zero. In addition, mean ΔrCBV in iADC (dADC) voxels on the tFDM was significantly higher (lower) than in iADC (dADC) voxels on the fcFDM.

Conclusion

The ability to accurately identify changes in diffusion on traditional FDMs is confounded in areas where perfusion and diffusion changes are colocalized. Flow‐compensated FDMs, which use only non‐zero b‐values, should therefore be the standard approach. J. Magn. Reson. Imaging 2013;38:868–875. © 2013 Wiley Periodicals, Inc.
Intracranial hyperthermia through local photothermal heating with a fiberoptic microneedle device
Authors: Hood R. Lyle , Rossmeisl John H. , Andriani Rudy T. , Wilkinson Ashley R. , Robertson John L. , Rylander Christopher G.
Published: February 2013

Background and Objectives

The fiberoptic microneedle device (FMD) seeks to leverage advantages of both laser‐induced thermal therapy (LITT) and convection‐enhanced delivery (CED) to increase volumetric dispersal of locally infused chemotherapeutics through sub‐lethal photothermal heat generation. This study focused on determination of photothermal damage thresholds with 1,064 nm light delivered through the FMD into in vivo rat models.

Materials and Methods

FMDs capable of co‐delivering laser energy and fluid agents were fabricated through a novel off‐center splicing technique involving fusion of a multimode fiberoptic to light‐guiding capillary tubing. FMDs were positioned at a depth of 2.5 mm within the cerebrum of male rats with fluoroptic temperature probes placed within 1 mm of the FMD tip. Irradiation (without fluid infusion) was conducted at laser powers of 0 (sham), 100, 200, 500, or 750 mW. Evans blue‐serum albumin conjugated complex solution (EBA) and laser energy co‐delivery were performed in a second set of preliminary experiments.

Results

Maximum, steady‐state temperatures of 38.7 ± 1.6 and 42.0 ± 0.9°C were measured for the 100 and 200 mW experimental groups, respectively. Histological investigation demonstrated needle insertion damage alone for sham and 100 mW irradiations. Photothermal damage was detected at 200 mW, although observable thermal damage was limited to a small penumbra of cerebral cortical microcavitation and necrosis that immediately surrounded the region of FMD insertion. Co‐delivery of EBA and laser energy presented increased volumetric dispersal relative to infusion‐only controls.

Conclusion

Fluoroptic temperature sensing and histopathological assessments demonstrated that a laser power of 100 mW results in sub‐lethal brain hyperthermia, and the optimum, sub‐lethal target energy range is likely 100–200 mW. The preliminary FMD–CED experiments confirmed the feasibility of augmenting fluid dispersal using slight photothermal heat generation, demonstrating the FMD's potential as a way to increase the efficacy of CED in treating MG. Lasers Surg. Med. 45: 167–174, 2013. © 2013 Wiley Periodicals, Inc.
A retrospective review of pain control by a two‐step irradiance schedule during topical ALA‐photodynamic therapy of non‐melanoma skin cancer
Authors: Zeitouni Nathalie C. , Paquette Anne D. , Housel Joseph P. , Shi Yi , Wilding Gregory E. , Foster Thomas H. , Henderson Barbara W.
Published: February 2013

Background and Objective

Photodynamic therapy (PDT) with topical δ‐aminolevulinic acid (ALA) of non‐melanoma skin cancers is often associated with treatment‐limiting pain. A previous study on basal cell carcinomas (BCCs) at Roswell Park Cancer Institute evaluated a two‐step irradiance scheme as a means of minimizing pain, preserving outcomes, and limiting treatment time. We used an initial low irradiance until 90% of the protoporphyrin IX was photobleached, followed by a high irradiance interval until the prescribed fluence was delivered. Success of this pilot investigation motivated integration of the protocol into routine practice. Here, we present a retrospective review of recent clinical experience in a broad patient population.

Study Design/Materials and Methods

This was a retrospective review of an existing dermatology database. Fourteen caucasion patients—nine men and five women, ages 18–80, with a total of 51 superficial and 73 nodular BCCs, and three Bowen's disease lesions—were included. ALA was applied to each lesion for approximately 4 hours. Lesions received an initial irradiance of 30–50 mW/cm2 for 20 J/cm2, followed by 150 mW/cm2 for a total fluence of 200–300 J/cm2. Pain was assessed using a visual analog scale (VAS). Clinical outcome was determined at 6–12 months.

Results

Median VAS scores were 1.0 for both irradiances. Five of 127 lesions required pain control with 1% xylocaine. Pain was strongly influenced by lesion location but not by lesion type, number, or size. Complete responses were achieved in 84.1% of BCCs, which compares favorably with reported results for single ALA‐PDT treatments. Two of three Bowen's disease lesions showed a complete response. Complete responses for nodular BCCs were 37%, which are also within the range of reported outcomes.

Conclusions

A two‐step irradiance protocol in ALA‐PDT effectively minimizes pain, maintains excellent clinical outcomes in superficial lesions, and adds minimal treatment time. Lasers Surg. Med. 45: 89–94, 2013. © 2013 Wiley Periodicals, Inc.
Global existence of solutions to a magnetohydrodynamic‐omega model
Authors: Fan Jishan , Zhou Yong
Published: February 2013

In this paper, some sufficient conditions in terms of the magnetic field are established to guarantee global existence of solutions to a magnetohydrodynamic‐omega model.
Novel Cathode Interlayers Based on Neutral Alcohol‐Soluble Small Molecules with a Triphenylamine Core Featuring Polar Phosphonate Side Chains for High‐Performance Polymer Light‐Emitting and Photovoltaic Devices
Authors: Chen Dongcheng , Zhou Hu , Liu Ming , Zhao Wei‐Ming , Su Shi‐Jian , Cao Yong
Published: February 2013

A new family of neutral alcohol‐soluble small molecular materials comprised of electron‐rich triphenylamine (TPA) and fluorene featuring phosphonate side chains (FEP) is reported, namely 3TPA‐FEP, 2TPA‐2FEP and TPA‐3FEP, which have different TPA and FEP contents. Due to their good solubility in polar solvents like alcohol, multilayer devices can be fabricated by a wet process from orthogonal solvents. Polymer light‐emitting devices with these materials as a cathode interlayer and Al as the cathode show greatly enhanced efficiencies in contrast to control devices without such a cathode interlayer, and their efficiencies are comparable with or even higher than devices with the low work‐function metal Ba/Al as the cathode. In addition, high‐performance polymer solar cells based on the poly[N‐9''‐hepta‐decanyl‐2,7‐carbazole‐alt‐5,5‐(4',7'‐di‐2‐thienyl‐2',1',3'‐benzothiadiazole)] (PCDTBT):[6,6]‐phenyl C71‐butyric acid methyl ester (PC71BM) system are also achieved with power conversion efficiencies of 7.21%, 6.90% and 6.89%, by utilizing 3TPA‐FEP, 2TPA‐2FEP and TPA‐3FEP as the cathode interlayer, respectively. These efficiencies are also much higher than those for control devices without the cathode interlayer. Although TPA is well‐known as a hole‐transport unit, the current findings indicate that alcohol‐soluble TPA‐based small molecules are also a promising cathode interlayer for both electron injection and extraction.

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An Extended Transaction Cost Model of Decision Rights Allocation in Franchising: The Moderating Role of Trust
Authors: Mumdziev Nada , Windsperger Josef
Published: February 2013

This study develops and tests an extended transaction cost model to explain the structure of decision rights in franchising. Results show that the inclusion of trust in the transaction cost model supplements the transaction cost explanation of the allocation of decision rights in franchising. On the basis of the data from the German franchise sector, we found that environmental uncertainty has a negative effect on the allocation of decision rights to franchisees because the franchisor exercises more control over local outlet decisions when the local market environment is highly uncertain. Contrary to the traditional transaction cost view, we found that behavioral uncertainty has a positive effect on the allocation of decision rights to franchisees. This result implies that franchisors are more likely to delegate decision rights to franchisees when they encounter difficulties in measuring franchisees' performance and controlling their behavior. Finally, trust has a moderating effect on the relationship between transaction cost variables and franchisor's propensity to delegate decision rights to franchisees. Copyright © 2013 John Wiley & Sons, Ltd.
Ocular Tremor in Parkinson's Disease Is Due to Head Oscillation
Authors: Kaski Diego , Saifee Tabish A. , Buckwell David , Bronstein Adolfo M.
Published: February 2013

Background

We investigated the origin of a recently reported ocular microtremor in patients with Parkinson's disease (PD).

Methods

Eye movements were recorded in 2 unselected patients with PD. Two recording techniques were used to control for artifacts: infrared video‐oculography and infrared scleral reflection techniques. Head movements were also recorded with 2 different accelerometers.

Results

We recorded ocular oscillations in both patients (microtremor). Ocular tremor was accompanied by a recordable (but clinically nonvisible) head tremor of equal fundamental frequency and high coherence with both the eye oscillation and a recordable limb tremor. The eye movements were in the opposite direction to the head oscillation (ie, compensatory) and were suppressed by head restraint. There was no subjective oscillopsia, nor ocular tremor on fundoscopy.

Conclusions

The “ocular tremor” observed in patients with PD disease is a compensatory eye movement secondary to transmitted head tremor, in agreement with clinical wisdom that these patients do not report oscillopsia. © 2013 Movement Disorder Society
Meromorphic solutions of an auxiliary ordinary differential equation using complex method
Authors: Yuan Wenjun , Li Yezhou , Lin Jianming
Published: February 2013

In this paper, we employ the complex method to obtain first all meromorphic solutions of an auxiliary ordinary differential equation and then find all meromorphic exact solutions of the classical Korteweg–de Vries equation, Boussinesq equation, ( 3 + 1)‐dimensional Jimbo–Miwa equation, and Benjamin–Bona–Mahony equation. Our results show that the method is more simple than other methods. Copyright © 2013 John Wiley & Sons, Ltd.
Monitoring and compensating phase imperfections in cine balanced steady‐state free precession
Authors: Fischer Rudolf Fritz , Barmet Christoph , Rudin Markus , Boesiger Peter , Pruessmann Klaas Paul , Kozerke Sebastian
Published: February 2013

Purpose

To analyze and correct for eddy current‐induced phase imperfections in cardiac cine balanced steady‐state free precession (bSSFP) imaging.

Methods

Eddy current‐induced phase offsets were measured for different phase‐encoding schemes using a higher order dynamic field camera. Based on these measurements, offset phases were corrected for in postprocessing and by run‐time phase compensation applying radiofrequency phase increments and additional compensatory gradient areas. The findings were validated using numerical simulations, phantom experiments, and in vivo cardiac scans.

Results

Depending on the phase‐encoding scheme, significant eddy current‐induced phase offsets were detected. Time‐varying phase offsets were observed at subsequent excitations leading to steady‐state distortions and hence to profile‐dependent amplitude modulations in k‐space. Taking into account measured k‐space trajectories algebraic image reconstruction allowed compensating imperfect spatial encoding. Correction of amplitude modulations was successfully accomplished by run‐time phase compensation.

Conclusion

Using magnetic field monitoring, artifacts in cine balanced steady‐state free precession caused by uncompensated eddy current fields can be significantly reduced. Magn Reson Med 70:1567–1579, 2013. © 2013 Wiley Periodicals, Inc.
Antibody cross‐reactivity and the viral aetiology of type 1 diabetes
Authors: Coppieters Ken T. , von Herrath Matthias
Published: February 2013

Type 1 diabetes (T1D) is caused by the destruction of insulin‐producing pancreatic β cells by the patient's immune system. While the underlying genetics and immunopathology are fairly well characterized, the environmental trigger remains unidentified. Numerous studies have centred on the role of enteroviruses as aetiological factors that could initiate or accelerate T1D development. The most convincing evidence to date consists of an array of reports documenting the presence of enteroviral nucleic acids in peripheral blood at diagnosis. A prominent hypothesis is that enteroviruses may infect the pancreatic islets and thus be responsible for the islet‐specific up‐regulation of MHC class I that is commonly observed, possibly enabling T cell recognition and cytotoxicity. Past immunohistochemical studies have indeed shown that antibodies binding the enteroviral capsid protein VP1 preferentially stain the pancreatic β cells from diabetic individuals. New data now indicate that the VP1 antibody used in these studies cross‐reacts with mitochondrial proteins. Copyright © 2013 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Surface resistance and diffusion characteristics of toluene into calcium carbonate‐ and polymer‐coated calcium carbonate‐filled natural rubber composites
Authors: Konar Bidyut B. , Saha Mausumi
Published: February 2013

Solvent absorption has been followed in compression‐molded rubber vulcanizates for toluene in natural rubber (gum), calcium carbonate (CC)‐filled natural rubber composites, and polymer‐encapsulated calcium carbonate (PCC)‐filled natural rubber composites. The surface resistance is found to affect the absorption process of the composites. Diffusion from the sample sides is considered for thickness and the diffusion coefficients corrected accordingly. Aspects of the effect of PMMA on the equilibrium toluene take up, Fickian mode of transport; transport coefficients; activation parameters; and crosslink density are studied. The sorption results have been interpreted in terms of first‐order kinetic model. The crosslink densities calculated from equilibrium sorption successfully to explain the transport coefficient values of the composites. POLYM. ENG. SCI., 53:2487–2497, 2013. © 2013 Society of Plastics Engineers
Contractile signaling pathways in mouse prostate smooth muscle
Authors: Kitazawa Toshio
Published: February 2013

BACKGROUND

Prostate smooth muscle plays an important role in the physiological ejection of prostatic fluid and also in the pathogenesis of benign prostate hyperplasia. Although mouse is the best genetically engineered animal model to identify potential molecular targets for human diseases, only fragmentary information is available for basic mechanism of mouse prostate contraction.

METHODS

Small smooth muscle tubular rings were excised from four mouse prostate lobes to measure their isometric contractions. High K+, noradrenaline (NA), or acetylcholine (ACh) was applied with and without various antagonists and/or inhibitors to examine the contractile signaling pathways.

RESULTS

Maximum amplitude of agonist‐induced contractions varied greatly with different lobes but not with different locations or orientations within each lobe. Both NA and ACh produced large contractions in ventral and dorsal rings, whereas only small contractions were elicited in lateral and anterior rings. Combination of alpha‐1 and muscarinic antagonists suppressed K+ depolarization‐induced contraction potently in ventral rings, but slightly in anterior rings. Blocking of either Ca2+‐release or Ca2+‐influx reduced agonist‐induced contraction of ventral rings, however, a considerable amount of contractility remained even with both blockers. Inhibitors of ROCK and PKC partially inhibited NA‐induced contractions, whereas a combination of Ca2+‐blockers and Ca2+‐sensitization inhibitors strongly suppressed the contraction.

CONCLUSIONS

The ejection of prostatic fluid is differentially regulated in each prostate lobe. In ventral prostate smooth muscle, Ca2+‐release, Ca2+‐influx, and ROCK‐ and PKC‐mediated Ca2+‐sensitizations are all involved in NA‐induced contractions. This finding is a useful step toward the understanding of the phenotypic changes in the smooth muscle of BPH prostate. Prostate 73: 996–1006, 2013. © 2013 Wiley Periodicals, Inc.
FOXO1 binds to the TAU5 motif and inhibits constitutively active androgen receptor splice variants
Authors: Bohrer Laura R. , Liu Ping , Zhong Jian , Pan Yunqian , Angstman James , Brand Lucas J. , Dehm Scott M. , Huang Haojie
Published: February 2013

BACKGROUND

Aberrant activation of the androgen receptor (AR) is a major factor highly relevant to castration‐resistant progression of prostate cancer (PCa). FOXO1, a key downstream effector of PTEN, inhibits androgen‐independent activation of the AR. However, the underlying mechanism remains elusive.

METHODS

The inhibitory effect of FOXO1 on full‐length and constitutively active splice variants of the AR was examined by luciferase reporter assays and real‐time reverse transcription polymerase chain reaction (RT‐qPCR). In vitro protein binding assays and western blot analyses were used to determine the regions in FOXO1 and AR responsible for their interaction.

RESULTS

We found that a putative transcription repression domain in the NH2‐terminus of FOXO1 is dispensable for FOXO1 inhibition of the AR. In vitro protein binding assays showed that FOXO1 binds to the transcription activation unit 5 (TAU5) motif in the AR NH2‐terminal domain (NTD), a region required for recruitment of p160 activators including SRC‐1. Ectopic expression of SRC‐1 augmented transcriptional activity of some, but not all AR splice variants examined. Forced expression of FOXO1 blocked the effect of SRC‐1 on AR variants' transcriptional activity by decreasing the binding of SRC‐1 to the AR NTD. Ectopic expression of FOXO1 inhibited expression of endogenous genes activated primarily by alternatively spliced AR variants in human castration‐resistant PCa 22Rv1 cells.

CONCLUSIONS

FOXO1 binds to the TAU5 motif in the AR NTD and inhibits ligand‐independent activation of AR splice variants, suggesting the PTEN/FOXO1 pathway as a potential therapeutic target for inhibition of aberrant AR activation and castration‐resistant PCa growth. Prostate 73: 1017–1027, 2013. © 2013 Wiley Periodicals, Inc.
Carrier dynamics and localization in AlInN/GaN heterostructures
Authors: Marcinkevičius Saulius , Liuolia Vytautas , Billingsley Daniel , Shatalov Maxim , Yang Jinwei , Gaska Remis , Shur Michael S.
Published: February 2013

Photoexcited carrier dynamics and localization potentials in Al0.86In0.14N/GaN heterostructure have been examined by time‐resolved photoluminescence (PL), transient photoreflectance and scanning near‐field optical spectroscopy. The large GaN and AlInN PL intensity difference, and the short AlInN PL decay and GaN PL rise times indicate efficient photoexcited carrier transfer from AlInN to GaN via sub‐band edge states. Near‐field PL scans and photoreflectance data show that the diameter of the localization sites and the distance between them are well below 100 nm. Majority of these states is assigned to In clusters, in which the valence band has a higher energy than the valence band in a uniform AlInN alloy. It is likely that the carrier transport through the sub‐band edge states proceeds via high conductivity channels involving extended defects. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Insulating behavior of interfaces in regrown Al0.23Ga0.77N/GaN double heterostructures on Al0.07Ga0.93N back‐barrier templates
Authors: Reuters B. , Hahn H. , Behmenburg H. , Heuken M. , Kalisch H. , Vescan A.
Published: February 2013

An important issue in multi‐step epitaxial growth processes are the electrical characteristics of regrown interfaces. Here, we present a study on interface quality and its effect onto insulating behavior and scattering effects in planar transistors. A double heterostructure with an AlGaN/GaN high electron mobility transistor on top of an AlGaN back‐barrier is used to assess electrical properties. Back‐barrier templates were exposed to air for several days and subsequently treated by wet and dry chemical etching. A strong impact on leakage behaviour of the regrown interface was observed. Lateral leakage currents as low as 1x10–8 A/mm are achieved with an optimized pre‐treatment. Furthermore, under optimized conditions, the regrown GaN channel thickness is varied to investigate the effect of different distances between the two‐dimensional electron gas (2DEG) and the regrown interface. Here, enhanced scattering mechanisms, probably due to ionized impurities, lead to a mobility drop of the 2DEG. A parasitic channel is observed, which indicates the presence of additional impurities at the regrown interface. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High quality strain‐compensated multiple InAs/AlGaNAs quantum dot layers grown by MBE
Authors: Ye Hong , Sadeghi Mahdad , Song Yuxin , Lai Zonghe , Gu Yi , Wang Shumin
Published: February 2013

Intermediate band solar cells have attracted significant interest as a possible means of achieving high conversion efficiency. Under optimized growth parameters, we successfully achieve a high density of uniform InAs QDs grown on various matrixes by molecular beam epitaxy. Incorporating N atoms into GaAs and AlGaAs barriers effectively compensates the internal compressive strain and avoids formation of dislocations and defects. The 50 stacking of high density and uniform InAs QDs was demonstrated without detectable dislocations using 26 nm GaNAs as a barrier. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Tensile strain‐induced formation of micro‐cracks for AlGaN/GaN heterostructures
Authors: Kotani Junji , Tomabechi Shuichi , Miyajima Toyoo , Nakamura Norikazu , Kikkawa Toshihide , Watanabe Keiji , Imanishi Kenji
Published: February 2013

This paper investigated the effect of tensile strain in AlGaN barrier layer on the formation of micro‐cracks at the surface of AlGaN/GaN HEMT structures. The Al0.2Ga0.8N/GaN HEMT structures were cooled down under N2 + NH3 and H2 + NH3 environments and high‐density micro‐cracks were found only for the latter case, indicating that hydrogen etching is essential for crack formation. On the other hand, no micro‐cracks were observed even for H2 + NH3 cooling for thick AlGaN bulk layer. These results clearly correlate the tensile strain in the epitaxial layer and the formation of micro‐cracks. Cross‐sectional TEM analysis unveiled that screw/mixed dislocations were responsible for the formation of micro‐cracks. It is believed that etching preferably starts from the dislocations and propagates along the crystal planes with the help of the tensile strain in the epitaxial layers. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
SEASONALLY DRIVEN VARIATION IN SPATIAL RELATIONSHIPS BETWEEN AGRICULTURAL LAND USE AND IN‐STREAM NUTRIENT CONCENTRATIONS
Authors: Yates A. G. , Brua R. B. , Corriveau J. , Culp J. M. , Chambers P. A.
Published: February 2013

Geographic information system (GIS) based distance weighted models were applied to determine critical areas of agricultural influence in nine agriculturally dominated, prairie subcatchments in southern Manitoba, Canada. Models were generated using a range of coefficients to represent nutrient overland and in‐stream attenuation between agricultural source areas and stream sampling stations. Coefficients were also used to represent increased attenuation during overland travel through areas with natural vegetation. Water samples collected at intervals throughout the open water season were used to establish associations between areas of influence and in‐stream total nitrogen and phosphorus concentrations in each season and under different flow conditions. Critical areas of influence varied seasonally with areas of influence expanding with individual rainfall events. Inclusion of natural vegetated areas on the landscape resulted in substantial increases in model power for only one scenario. Agriculture in areas within approximately 100 m of the stream channel appears to be the most critical driver of in‐stream nutrient conditions during most seasons and under most flow conditions. Best management practices, such as vegetated buffer strips, should be most effective in controlling nutrient losses to southern Manitoba streams when situated within stream corridor, as opposed to upland areas, which appear to have minimal impact on in‐stream conditions. Copyright © 2013 John Wiley & Sons, Ltd.
Effect of Low Oxygen Partial Pressure on the Chromium Partition in CaO–MgO–SiO2–Cr2O3–Al2O3 Synthetic Slag at Elevated Temperatures
Authors: Albertsson Galina , Teng Lidong , Björkman Bo , Seetharaman Seshadri , Engström Fredrik
Published: February 2013

The objective of the present work is to get an understanding of the impact of Al2O3 addition on the phase relationships in the CaO–MgO–Al2O3–SiO2–Cr2O3 slags at low oxygen partial pressures (${\rm P}_{{\rm O}_{2} } $ = 10−4 Pa), with a view to control the precipitation of Cr‐spinel in the slag. The equilibrium phases in CaO–MgO–Al2O3–SiO2–Cr2O3 slag system in the range on 1673–1873 K have been investigated. The compositions close to the industrial slag systems were chosen. The Cr2O3 content was fixed at 6 wt% and MgO at 8 wt%. Al2O3 contents in the slag were varied in the range of 3–12 wt%. The basicity (CaO/SiO2) of slag was set to 1.6. Gas/slag equilibrium technique was adopted. The samples were heated to 1873 K and soaked at this temperature for 24 h. The samples were then slow cooled to 1673 K and equilibrated for an additional 24 h. The oxygen partial pressure was kept at 10−4 Pa. A gas mixture of CO/CO2 was used to control the oxygen partial pressure. After the equilibration, the samples were quenched in water. The chromium distribution and phase compositions in the quenched slags were studied using SEM–WDS and XRD techniques. The results were compared with the phase equilibrium calculations obtained from FACTSAGE software and the samples equilibrated in air. The size of spinel crystals increased drastically after slow cooling followed by annealing compared to samples being quenched after soaking at 1873 K. It was also found that low oxygen partial pressure had a strong impact on chromium partition. The amount of spinel phase increases with increased Al2O3 content.
Assembly of the steel roof structure for the football stadium in Gdan´sk
Authors: Ziółko Jerzy , Les´niak Alojzy
Published: February 2013

The technology of assembling the roof over the stadium built in Gdan´sk for the EURO 2012 European Football Championship is discussed here. The stadium has a characteristic silhouette – its shape and the colours of the façade resemble a cut block of amber. The steel roof structure has a quasi‐elliptical form, with a maximum diameter of 220 m and minimum diameter of 187 m. It is 38 m high and the roof girders extend 48 m over the grandstand below. The roof structure weights 7150 t and was assembled in 226 days.
The aluminium and polycarbonate covering to the roof over the stadium in Gdan´sk
Authors: Kowalski Dariusz
Published: February 2013

This paper presents information about structural elements of the roof covering to the stadium in Gdan´sk built for the 2012 European Football Championship in Poland and the Ukraine. The paper discusses elements of the polycarbonate covering, the supporting structure and the drainage system. It also provides information about tests and research performed prior to construction, which determined the solutions adopted as well as the roof’s present and future condition.
Navigation and steering for autonomous virtual humans
Authors: Kapadia Mubbasir , Badler Norman I.
Published: February 2013

The ever‐increasing applicability of interactive virtual worlds in industry and academia has given rise to the need for robust, versatile autonomous virtual humans to inject life into these environments. There are two fundamental problems that must be addressed to produce functional, purposeful autonomous populaces: (1)Navigation: finding a collision‐free global path from an agent's start position to its target in large complex environments, and (2) Steering: moving an agent along the path while avoiding static and dynamic threats such as other agents. In this review, we survey the large body of contributions in steering and navigation for autonomous agents in dynamic virtual worlds. We describe the benefits and limitations of different proposed solutions and identify potential future research directions to meet the needs for the next generation of interactive virtual world applications. WIREs Cogn Sci 2013, 4:263–272. doi: 10.1002/wcs.1223

This article is categorized under:

Computer Science > Artificial Intelligence
Large‐scale hydrologic and hydrodynamic modeling of the Amazon River basin
Authors: de Paiva Rodrigo Cauduro Dias , Buarque Diogo Costa , Collischonn Walter , Bonnet Marie‐Paule , Frappart Frédéric , Calmant Stephane , Bulhões Mendes Carlos André
Published: February 2013

Key Points

Remote sensing validation of a hydrologic‐hydrodynamic model of the Amazon

Uncertainty of precipitation and river‐floodplain parameters cause model errors

Importance of floodplains and backwater effects on flood waves traveling
Data‐based comparison of frequency analysis methods: A general framework
Authors: Renard B. , Kochanek K. , Lang M. , Garavaglia F. , Paquet E. , Neppel L. , Najib K. , Carreau J. , Arnaud P. , Aubert Y. , Borchi F. , Soubeyroux J.‐M. , Jourdain S. , Veysseire J.‐M. , Sauquet E. , Cipriani T. , Auffray A.
Published: February 2013

Key Points

A general framework for comparing frequency analysis methods

Focus is on the predictive performance of frequency analysis methods

Reliability of uncertainty estimates is assessed using a predictive distribution
Pore‐scale evaluation of uranyl phosphate precipitation in a model groundwater system
Authors: Fanizza Michael F. , Yoon Hongkyu , Zhang Changyong , Oostrom Martinus , Wietsma Thomas W. , Hess Nancy J. , Bowden Mark E. , Strathmann Timothy J. , Finneran Kevin T. , Werth Charles J.
Published: February 2013

Key Points

In situ uranyl phosphate precipitation is fast on the time scale of remediation

Ca2+ & SO42‐ affect uranyl phosphate precipitation rate and morphology

Only chernikovite is formed, and it blocks pore spaces and reduces mixing
In bad waters: Water year classification in nonstationary climates
Authors: Null Sarah E. , Viers Joshua H.
Published: February 2013

Key Points

The frequency of water year types changes significantly with climate change.

Strategies to adapt water year classification indices affect water allocations.

Water year indices determine how much water ecosystems receive.
Tree rings and multiseason drought variability in the lower Rio Grande Basin, USA
Authors: Woodhouse C. A. , Meko D. M. , Griffin D. , Castro C. L.
Published: February 2013

Key Points

A new tree‐ring data network is used to reconstruct the southwestern US monsoon

Reconstructions indicate low Rio Grande flow followed by a dry summer is common

The severity of the current Rio Grande basin drought is not yet unprecedented
Influence of constant rate versus slug injection experiment type on parameter identifiability in a 1‐D transient storage model for stream solute transport
Authors: Wlostowski Adam N. , Gooseff Michael N. , Wagener Thorsten
Published: February 2013

Key Points

Dispersion is more sensitive using slugs than using constant rate methods

Storage zone area is more sensitive using constant rate than slug methods

Monte Carlo sensitivity analysis methods reveal information content of data
Recognizing and modeling variable drawdown due to evapotranspiration in a semiarid riparian zone considering local differences in vegetation and distance from a river source
Authors: Johnson Brady , Malama Bwalya , Barrash Warren , Flores Alejandro N.
Published: February 2013

Key Points

Analytical model developed for river leakage contribution to riparian zone ET

River contributions to ET can be distinguished in relative drawdown at wells

Improved relative contributions to ET from river and aquifer can be calculated
Invariant differential operators for non-compact Lie algebras parabolically related to conformal Lie algebras
Authors: Dobrev V. K.
Published: February 2013

Abstract

In the present paper we continue the project of systematic construction of invariant differential operators for non-compact semisimple Lie groups. Our starting points is the class of algebras, which we call ’conformal Lie algebras’ (CLA), which have very similar properties to the conformal algebras of Minkowski space-time, though our aim is to go beyond this class in a natural way. For this we introduce the new notion ofparabolic relationbetween two non-compact semisimple Lie algebrasGandG′that have the same complexification and possess maximal parabolic subalgebras with the same complexification. Thus, we consider the exceptional algebraE7(7)which is parabolically related to the CLAE7(−25), the parabolic subalgebras includingE6(6)andE6(−26). Other interesting examples are the orthogonal algebras so(p, q) all of which are parabolically related to the conformal algebraso(n, 2) withp+q=n+ 2, the parabolic subalgebras including the Lorentz subalgebra so(n− 1, 1) and its analogs so(p− 1,q− 1). We consider also E6(6)and E6(2)which are parabolically related to the hermitian symmetric case E6(−14), the parabolic subalgebras including real forms of sl(6).

We also give a formula for the number of representations in the main multiplets valid for CLAs and all algebras that are parabolically related to them. In all considered cases we give the main multiplets of indecomposable elementary representations including the necessary data for all relevant invariant differential operators. In the case ofso(p,q) we give also the reduced multiplets. We should stress that the multiplets are given in the most economic way in pairs ofshadow fields. Furthermore we should stress that the classification of all invariant differential operators includes as special cases all possibleconservation lawsandconserved currents, unitary or not.
Study of Micellization of Sodium Dodecyl Sulfate in Non‐Aqueous Media Containing Lauric Acid and Dimethylsulfoxide
Authors: Ali Anwar , Nabi Firdosa , Malik Nisar Ahmad , Tasneem Shadma , Uzair Sahar
Published: February 2013

Interactions between dimethylsulfoxide (DMSO), lauric acid (LA) and anionic surfactant, sodium dodecyl sulfate (SDS) in non‐aqueous media have been studied in detail using conductometric, volumetric, and ultrasonic speed techniques. Conductivities, densities and ultrasonic speeds of 1 × 10−3 to 11 × 10−3 m SDS solutions in a mixture of LA (0.10 m) and DMSO between 298.15 and 313.15 K have been measured. The experimental data have been correlated against temperature and concentration of SDS using standard relations. The critical micelle concentration (CMC) values have been determined by using different methods like conductance, density and ultrasonic speed. All the methods yielded identical CMC values. The measured data were used to calculate various useful thermodynamic parameters like standard free energy, , enthalpy, , and entropy, , of micelle formation. From the density data of the surfactant, the change of the apparent molar volume upon micellization has been calculated. Density and ultrasonic speed data were used to evaluate the apparent molar adiabatic compressibility for the micelle of the surfactant at different temperatures over a wide concentration range.
Antimicrobial Catanionic Vesicular Self‐Assembly with Improved Spectrum of Action
Authors: Chaouat Clara , Balor Stéphanie , Roques Christine , Franceschi‐Messant Sophie , Perez Emile , Rico‐Lattes Isabelle
Published: February 2013

A catanionic mixture based on three components, N‐dodecyldiethanolamine, decanoic acid and azelaic acid, was prepared and investigated from a physico‐chemical point of view and for its antimicrobial activity. The spontaneously formed vesicles were characterized by dynamic light scattering, zeta potential and electron microscopy. These experiments showed spherical vesicles with an average diameter of 200 nm and a zeta potential of +22 mV. The antimicrobial activity of the vesicle dispersion against different strains (Staphylococcus aureus, Escherichia coli, Staphylococcus epidermidis, Propionibacterium acnes and Candida albicans), was evaluated and compared with the activity of the components separately. The synergistic effect of these bioactive self‐assembled catanionic vesicles on the spectrum of activity and on the cytoplasmic membrane is discussed.
Higher Serum EPA or DHA, and Lower ARA Compositions with Age Independent Fatty Acid Intake in Japanese Aged 40 to 79
Authors: Otsuka Rei , Kato Yuki , Imai Tomoko , Ando Fujiko , Shimokata Hiroshi
Published: February 2013

Docosahexaenoic acid (DHA) and arachidonic acid (ARA) are the predominant long‐chain polyunsaturated fatty acids (PUFA) among membrane phospholipids in the mammalian brain and neural tissues. This cross‐sectional study examined age effects on serum eicosapentaenoic acid (EPA), DHA, and ARA compositions assessed with reference to dietary intakes among 1,014 Japanese men and 1,028 Japanese women aged 40–79 years. Venous blood was collected early in the morning after at least 12‐h fasting. Serum fatty acid (FA) compositions were expressed as molar percentages of the total FA (mol% of total). Diet was assessed using a 3‐day dietary record that included photographs. Participants were categorized into groups by sex and age (40–49, 50–59, 60–69, and 70–79 years). Intakes of fish, EPA, and DHA tended to increase with age. Significant positive correlations between serum FA composition and the corresponding weight percentage of total FA intake were observed for EPA and DHA in all sex and age groups, and for ARA among females in their 40s. Serum EPA and DHA compositions were higher, while ARA decreased with age, and these associations remained consistent even after adjusting for corresponding FA intake. These results suggest potential effects of age on differences in blood EPA, DHA, and ARA compositions, independent of corresponding FA intake among community‐dwelling Japanese men and women.
Biometric identification of capillariid eggs from archaeological sites in Patagonia
Authors: Taglioretti V. , Fugassa M.H. , Beltrame M.O. , Sardella N.H.
Published: February 2013

Numerous eggs of capillariid nematodes have been found in coprolites from a wide range of hosts and in raptor pellets in archaeological samples from Patagonia. The structure and sculpture of the eggshell of these nematodes and their biometry are commonly used for identification. The aim of this study was to determine whether eggs of the genusCalodiumwith similar morphology, found in different archaeological samples from Patagonia, belong to the same species. For this purpose, capillariid eggs (N= 843) with thick walls and radial striations were studied by permutational multivariate analysis of variance (PERMANOVA). Eggs exhibiting similar shape and structure also showed similar biometry, regardless of the zoological origin of coprolites (P= 0.84), host diet (P= 0.19), character of the archaeological sites (P= 0.67) and chronology (P= 0.66). Thus, they were attributed to the same species. We suggest that an unidentified zoonotic species of the genusCalodiumoccurred in the digestive tract of a wide range of hosts in Patagonia during the Holocene and that both human and animal populations were exposed to this parasite during the Holocene in the study area.
The occurrence of zoonotic parasites in rural dog populations from northern Portugal
Authors: Cardoso A.S. , Costa I.M.H. , Figueiredo C. , Castro A. , Conceição M.A.P.
Published: February 2013

A survey of intestinal parasites in dogs was carried out in a rural region around Cantanhede, in northern Portugal, where 301 dog faecal samples were collected from small-ruminant farms. Saturated salt flotation and formol–ether sedimentation techniques were used. An enquiry was conducted in 234 farms and a risk factor evaluation for zoonotic helminths was determined among the 195 farmers who owned dogs. The overall parasite prevalence in faecal samples of dogs was 58.8%, with specific prevalences for Ancylostomidae being 40.9% followed by species of Trichuris (29.9%), Toxocara (8%), Isospora (4%), Capillaria (0.7%) and Spirometra (0.3%). Taeniidae eggs were present in five samples (1.7%) which were analysed with the polymerase chain reaction (PCR) technique and revealed to be from Taenia sp., and not Echinococcusgranulosus. This rural region has a traditional small-farm system, in which farm products are mainly for in-house consumption and home slaughtering is a current practice (57%). Analysis showed home slaughtering to be a statistically significant risk factor for the presence of Ancylostomidae (P= 0.007) and Toxocara sp. (P= 0.049). Owning cattle was found to be a significant risk factor for Taenia sp. (P= 0.031).