bluuebunny/crossref_metadata_2025 huggingface dataset:
Fiberlike Micelles Formed by Living Epitaxial Growth from Blends of Polyferrocenylsilane Block Copolymers
Authors: Cambridge Graeme , Guerin Gerald , Manners Ian , Winnik Mitchell A.
Published: May 2010

Poly(ferrocenyldimethylsilane) (PFS) block copolymers form fiberlike micelles by a seeded growth process. This paper describes the effect of adding similar amounts of PFS block copolymers, PFS–PDMS and PFS–PI, to a common micelle seed. The lengths of the micelles obtained were strongly influenced by the degree of polymerization of the corona‐forming blocks. The change in length was due to a change in the number of polymer molecules per unit length of the micelle.

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Hyperactive putamen in patients with paroxysmal kinesigenic choreoathetosis: A resting‐state functional magnetic resonance imaging study
Authors: Zhou Bo , Chen Qin , Zhang Qin , Chen Lei , Gong Qiyong , Shang Huifang , Tang Hehan , Zhou Dong
Published: May 2010

Paroxysmal kinesigenic choreoathetosis (PKC) is a rare neurologic disorder characterized by sudden attacks of brief involuntary dyskinetic movement, which are precipitated by voluntary movement. The pathophysiology of PKC remains unclear. The purpose of this study is to localize cerebral functional abnormalities in idiopathic PKC with resting‐state functional magnetic resonance imaging (fMRI). From May 2007 to August 2008, seven patients with idiopathic PKC were included. The mean age of onset was 11.7 ± 3.1 (range, 8–17) years and the mean disease duration was 6.9 ± 5.1 (range, 1–14) years. Seven subjects of an age‐ and sex‐matched control group were recruited. Interictal brain fMRI was performed in the PKC patients and in the normal controls. Voxel‐based analysis was used to characterize the alteration of amplitude of low frequency fluctuation (ALFF) in patients with PKC. Difference between the patient patterns and the control was analyzed with Student t‐test. The whole brain analysis indicated that the patient group had significantly increased ALFF in the bilateral putamen (P < 0.005) than normal control. fMRI could be useful to evaluate PKC with negative conventional imaging. It was suggested that abnormal cortico‐striato‐pallido‐thalamic loop might be associated with the pathophysiology of idiopathic PKC. © 2010 Movement Disorder Society
Communicating uncertainty in hydro‐meteorological forecasts: mission impossible?
Authors: Ramos Maria‐Helena , Mathevet Thibault , Thielen Jutta , Pappenberger Florian
Published: May 2010

There is a common agreement in the scientific community that communicating uncertain hydro‐meteorological forecasts to water managers, civil protection authorities and other stakeholders is far from being a resolved issue. This paper focuses on the communication of uncertain hydrological forecasts to decision‐makers such as operational hydrologists and water managers in charge of flood warning and scenario‐based reservoir operation. Results from case studies conducted together with flood forecasting experts in Europe and operational forecasters from the hydroelectric sector in France are presented. They illustrate some key issues on dealing with probabilistic hydro‐meteorological forecasts and communicating uncertainty in operational flood forecasting. Copyright © 2010 Royal Meteorological Society
Salvage of SIEA flaps using the retrograde internal mammary system
Authors: Agarwal Jayant P. , Ley Eleazar , Tieman Josh
Published: May 2010

Superficial inferior epigastric artery (SIEA) flaps are ideal for breast reconstruction when the anatomy permits it. Due to the peripheral and superficial location of the pedicle, these flaps can be complicated by vessel kinking against the remaining ribs after insetting. Here, we describe a novel method for SIEA flap salvage after kinking or avulsion of the traditional anastomosis to the internal mammary vessels. © 2010 Wiley‐Liss, Inc. Microsurgery 30:545–548, 2010.
‘tieredScreen’ – Layered Virtual Screening Tool for the Identification of Novel Estrogen Receptor Alpha Modulators
Authors: Yang Yidong , Carta Giorgio , Peters Martin B. , Price Trevor , O'Boyle Niamh , Knox Andrew J. S. , Fayne Darren , Williams D. Clive , Meegan Mary J. , Lloyd David G.
Published: May 2010

A novel tiered Structure‐Based (SB) Virtual Screening (VS) workflow called tieredScreen was designed and implemented. The automated protocol utilises diverse computational tools in a synergistic manner to reduce false positives and increase the likelihood of converging on putative active molecules. The performance of the novel VS workflow was validated using the Directory of Useful Decoys (DUD) Estrogen Receptor α (ERα) antagonist dataset, and successfully deployed for the identification of novel antagonists of ERα from a screening collection of ca. 160 000 commercially available compounds. As well as yielding nanomolar (nM) active ligands identified previously through a docking only protocol, from a selection of eight virtual hits suggested by tieredScreen, four novel nM ERα binding chemotypes were identified and biologically validated – demonstrating the applicability of a tiered intervention for virtual screening.
Synthesis and NMR spectral assignments of indol‐3‐yl pyridines through one‐pot multi‐component reaction
Authors: Thirumurugan Prakasam , Nandakumar A. , Vidhya Lakshmi Neelakandan , Phani Kumar B. V. N. , Perumal Paramasivan T.
Published: May 2010

Asimple protocol for the efficient preparation of 6‐(ferrocene‐1‐yl)‐2‐(indol‐3‐yl)pyridine and 2‐(1H‐indol‐3‐yl)‐6‐(2‐thienyl)pyridine derivatives has been achieved through multi‐component reaction, and these compounds were thoroughly characterised by 2D NMR spectral techniques. Copyright © 2010 John Wiley & Sons, Ltd.
QRS prolongation in myotonic muscular dystrophy and diffuse fibrosis on cardiac magnetic resonance
Authors: Nazarian Saman , Bluemke David A. , Wagner Kathryn R. , Zviman Menekhem M. , Turkbey Evrim , Caffo Brian S. , Shehata Monda , Edwards David , Butcher Barbara , Calkins Hugh , Berger Ronald D. , Halperin Henry R. , Tomaselli Gordon F.
Published: May 2010

Current noninvasive surrogates of cardiac involvement in myotonic muscular dystrophy have low positive predictive value for sudden death. We hypothesized that the cardiac MR signal‐to‐noise ratio variance (SNRV) is a surrogate of the spatial heterogeneity of myocardial fibrosis and correlates with electrocardiography changes in myotonic muscular dystrophy. The SNRV for contrast enhanced cardiac MR images was calculated over the entire left ventricle in 43 patients with myotonic muscular dystrophy. All patients underwent standard electrocardiography, and a subset of 23 patients underwent signal averaged electrocardiography. After correcting for body mass index, age, and ejection fraction, SNRV was predictive of QRS duration on standard electrocardiography (1.35‐msec increased QRS duration/unit increase in SNRV, P < 0.001). SNRV was also predictive of the low‐amplitude late‐potential duration (1.49‐msec increased low‐amplitude late‐potential duration/unit increase in SNRV, P < 0.001). Ten‐fold cross‐validation yielded an area under the receiver operating characteristic curve of 0.87 for the predictive value of SNRV for QRS duration greater than 120 msec. The SNRV of the left ventricle is associated with QRS prolongation, likely due to late depolarization of tissue within islands of patchy fibrosis. The association of SNRV with future clinical events warrants further study. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
Tracer kinetic analysis of dynamic contrast‐enhanced MRI and CT bladder cancer data: A preliminary comparison to assess the magnitude of water exchange effects
Authors: Bains Lauren J. , McGrath Deirdre M. , Naish Josephine H. , Cheung Susan , Watson Yvonne , Taylor M. Ben , Logue John P. , M. Parker Geoffrey J. , Waterton John C. , Buckley David L.
Published: May 2010

The purpose of this study was to determine the impact of water exchange on tracer kinetic parameter estimates derived from T1‐weighted dynamic contrast‐enhanced (DCE)‐MRI data using a direct quantitative comparison with DCE‐CT. Data were acquired from 12 patients with bladder cancer who underwent DCE‐CT followed by DCE‐MRI within a week. A two‐compartment tracer kinetic model was fitted to the CT data, and two versions of the same model with modifications to account for the fast exchange and no exchange limits of water exchange were fitted to the MR data. The two‐compartment tracer kinetic model provided estimates of the fractional plasma volume (vp), the extravascular extracellular space fraction (ve), plasma perfusion (Fp), and the microvascular permeability surface area product. Our findings suggest that DCE‐CT is an appropriate reference for DCE‐MRI in bladder cancers as the only significant difference found between CT and MR parameter estimates were the no exchange limit estimates of vp (P = 0.002). These results suggest that although water exchange between the intracellular and extravascular‐extracellular space has a negligible effect on DCE‐MRI, vascular–extravascular‐extracellular space water exchange may be more important. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
A fast hierarchical dual boundary element method for three‐dimensional elastodynamic crack problems
Authors: Benedetti I. , Aliabadi M. H.
Published: May 2010

In this work a fast solver for large‐scale three‐dimensional elastodynamic crack problems is presented, implemented, and tested. The dual boundary element method in the Laplace transform domain is used for the accurate dynamic analysis of cracked bodies. The fast solution procedure is based on the use of hierarchical matrices for the representation of the collocation matrix for each computed value of the Laplace parameter. An ACA (adaptive cross approximation) algorithm is used for the population of the low rank blocks and its performance at varying Laplace parameters is investigated. A preconditioned GMRES is used for the solution of the resulting algebraic system of equations. The preconditioners are built exploiting the hierarchical arithmetic and taking full advantage of the hierarchical format. An original strategy, based on the computation of some local preconditioners only, is presented and tested to further speed up the overall analysis. The reported numerical results demonstrate the effectiveness of the technique for both uncracked and cracked solids and show significant reductions in terms of both memory storage and computational time. Copyright © 2010 John Wiley & Sons, Ltd.
Dual Grid Lattice Boltzmann method for multiphase flows
Authors: Rosales C. , Whyte D. S.
Published: May 2010

We present a new methodology for implementing multiphase flow solvers using the Lattice Boltzmann method. Two grids of different size are used to discretize the momentum and the order parameter so that derivatives of the latter (responsible for the forcing terms at the interfaces) are calculated with high accuracy while maintaining a moderate computational cost. We apply the technique to two recently proposed formulations of the multiphase Lattice Boltzmann method, and show that this technique produces significant improvements over a homogeneous mesh refinement in both cases. Copyright © 2010 John Wiley & Sons, Ltd.
Layerwise zig‐zag model with selective refinement across the thickness
Authors: Icardi U. , Ferrero L.
Published: May 2010

In this paper a multilayered model with a hierarchic representation of displacements is developed. The representation, which is based on Jacobi polynomials, can be different for any computational layer, from point to point across the thickness and for any functional d.o.f., aimed at adapting the model to the local variations of solutions. This refinement is obtained by keeping the number of d.o.f. unchanged. The displacements are described through a zig‐zag representation in any computational layer, in order to fulfil the stress contact conditions at the inner interfaces. A displacement‐based version of the model with the six displacement components at the upper and lower faces as functional d.o.f. and a mixed version with the six interlayer stress components are developed. The numerical results mainly concern simply supported thick sandwich beams under sinusoidal loading, but results are also presented for thin cantilevered sandwich beams and laminated plates. The model accurately predicts displacements and stress fields using a single computational layer, even when material properties abruptly change. The computational effort for the adaptive representation is advantageous by the viewpoint with respect to a fixed representation or with the use of post‐processing methods. Copyright © 2010 John Wiley & Sons, Ltd.
Using the clustered circular layout as an informative method for visualizing protein–protein interaction networks
Authors: Fung David C. Y. , Wilkins Marc R. , Hart David , Hong Seok‐Hee
Published: May 2010

The force‐directed layout is commonly used in computer‐generated visualizations of protein–protein interaction networks. While it is good for providing a visual outline of the protein complexes and their interactions, it has two limitations when used as a visual analysis method. The first is poor reproducibility. Repeated running of the algorithm does not necessarily generate the same layout, therefore, demanding cognitive readaptation on the investigator's part. The second limitation is that it does not explicitly display complementary biological information, e.g. Gene Ontology, other than the protein names or gene symbols. Here, we present an alternative layout called the clustered circular layout. Using the human DNA replication protein–protein interaction network as a case study, we compared the two network layouts for their merits and limitations in supporting visual analysis.
Solvent control on the electron transfer reaction between CoIII(en)2Br(L)2+–Fe(CN) (L = aryl amines) by regression relationships: the PXRD and electrochemical investigations
Authors: Anbalagan K. , Lydia I. S.
Published: May 2010

Solvent shell coupled electron transfer (ET) reaction, principally between CoIII(en)2Br(L)2+ and Fe(CN) complexes (L = RC6H4NH2; R = m‐OCH3, p‐F, H, m‐CH3, p‐CH3, p‐OC2H5, and p‐OCH3) in H2O/EtOH binary mixed solvents has been investigated. The cobalt(III)‐aryl amine complexes have been structurally refined by powder X‐ray diffraction (PXRD) data as monoclinic unit cell with a distorted geometry. Cyclic voltammograms of the complexes exhibit CoIII/CoII and CoII/CoI reduction peaks with an indication of participation of electron accepting/donating abilities of RC6H4NH2 in the reduction. The ΔEp (50–580 mV) and Ic/ν½ (0.12–2.83) values differ for the complexes. ET between CoIII(en)2Br(L)2+ and Fe(CN) is due to ion pair, {CoIII(en)2Br(L)2+; Fe(CN)}, formation leading to product via (i) solvent caged ({CoIII…FeII}, restricted mobility due to RC6H4NH2) and (ii) solvent controlled (electron accepting/donating substituent in aryl ligand concertedly alters the equilibrium: reactants ↔ ion pair) mechanisms. Reduction was followed in 0–30% v/v (x2: xEtOH = 0, 0.0159–0.1162) aqueous ethanol solutions at 286, 293, and 300 K. Reaction follows second‐order condition and there is a gradation in rate when x2 = 0–0.1162 representing co‐solvent influence. This tendency is understood in the attainment of equilibrium and the formed compact ion pair. In order to estimate the solvent influence, the rate data were subjected to linear and multiple regression analyses using Ys = Y0 + a1X1 + a2X2 + a3X3…anXn correlation relationship. Copyright © 2010 John Wiley & Sons, Ltd.
Pulmonary hypertension secondary to partial pulmonary venous obstruction in a child with Cantu syndrome
Authors: Kobayashi Daisuke , Cook Amanda L. , Williams Derek A.
Published: May 2010

We report on an African‐American male with Cantu syndrome who required a pericardial window for a significant pericardial effusion in infancy and was subsequently found to have partial pulmonary venous obstruction (PVO) leading to pulmonary hypertension. Measurement of bilateral pulmonary capillary wedge pressures is important to uncover partial PVO. Pediatr Pulmonol. 2010; 45:727–729. © 2010 Wiley‐Liss, Inc.
Utilization of a second caregiver in the care of a child with a tracheostomy in the homecare setting
Authors: Tolomeo Concettina (Tina) , Bazzy‐Asaad Alia
Published: May 2010

Objective

To safely discharge a child with a tracheostomy tube to home, we require two legal guardians/parents to complete a special training program. However, there are times when two parents/guardians are unavailable or unwilling to be trained. Therefore, the purpose of this study was to evaluate the role of the second caregiver of a child with a tracheostomy tube in the home setting.

Methods

A retrospective, descriptive, qualitative, pilot study of a convenience sample of parents of 16 children who were discharged from the hospital with a tracheostomy tube between September 2004 and December 2008 was conducted. Data were obtained from the unit's discharge database and from the primary and/or secondary caregivers. Univariate analyses were used to determine the frequency of primary and secondary caregiver participation at home. Themes were generated from caregiver responses regarding utilization of a second caregiver in the home.

Results

A majority (93.8%, n = 15) reported primary caregivers participating very often in the care of the infant at home; less than half (31.3%, n = 5) reported comparable secondary caregiver participation. Fifty percent (n = 8) said they would not be able to care for the infant at home without another trained caregiver. Analysis of the caregiver responses revealed three major themes: confidence, safety, and respite/support.

Conclusion

Findings support the importance of training two caregivers in the care of a child being discharged with a tracheostomy tube. Training should include the medical/nursing care of the child as well as anticipatory guidance regarding what to expect and the need for respite services. Pediatr Pulmonol. 2010; 45:656–660. © 2010 Wiley‐Liss, Inc.
“Atypical steroid response” in a pulmonary inflammatory myofibroblastic tumor
Authors: Sacco Oliviero , Gambini Claudio , Gardella Chiara , Tomà Paolo , Rossi Umberto G. , Jasonni Vincenzo , Bush Andrew , Rossi Giovanni A.
Published: May 2010

A 6‐year‐old girl was evaluated for the presence of a paratracheal mass with right upper lobe atelectasis due to an endobronchial mass. Bronchoscopic biopsy established a diagnosis of inflammatory myofibroblastic tumor (IMT) and prednisone initially led to a significant reduction of the endobronchial lesion. However, 8 weeks later, when still on prednisone, the mediastinal mass enlarged dramatically. At thoracotomy, a well‐circumscribed, multilobulated mass was partially resected and a diagnosis of IMT confirmed. Immunosuppression by corticosteroids may have favored the rapid progression of this apparently benign, indolent tumor. Pediatr Pulmonol. 2010; 45:721–726. © 2010 Wiley‐Liss, Inc.
Diffuse chondroid malformation of the lung: Cases series of a hitherto undescribed congenital lung disease
Authors: Reix Philippe , Wanin Stéphanie , Dijoud Fréderique , Brouard Jacques , Epaud Ralph , Pracros Jean‐Pierre , Boccon‐Gibod Liliane , Bellon Gabriel
Published: May 2010

Congenital chondroid lesions of the lung are rare pathological findings. They are a constant feature of lung malformations such as giant cystic pulmonary chondroid hamartoma, chondroid cystic malformation, and in the “cartilaginous variant” of congenital adenomatoid malformation. All of these present as a large single thoracic mass.

We present the cases of three males and two females with hitherto undescribed diffuse chondroid lung disease, all but one of whom had neonatal respiratory distress syndrome with interstitial syndrome on chest radiograph. The pathological findings were similar in all patients, showing large areas of disorganized lung parenchyma containing diffusely distributed mature cartilage islands. With a mean follow‐up of 6 years, all patients had a favorable outcome. This diffuse chondroid lung disease appears to be a new entity whose initial presentation mimicked interstitial lung disease without the usual clinical, radiological, and histological features. We speculate that it could be part of a clinical spectrum between malformative chondroid lung cyst and congenital pulmonary airway malformation. Pediatr Pulmonol. 2010; 45:667–673. © 2010 Wiley‐Liss, Inc.
Balloon dilatation in management of postoperative airway obstruction due to tracheal bronchus associated with right main bronchial stenosis: Emphasizing the role of three‐dimensional computed tomography on preoperative evaluation
Authors: Kuo Shu‐Min , Yang Ming‐Ling , Li Yi‐Ching , Tsao Teng‐Fu , Liu Shu‐Chuan , Chen Fong‐Lin
Published: May 2010

Three‐dimensional computed tomography (3D‐CT) not only allows accurate preoperative delineation of the lesions but also provides precise pathomechanic diagnosis for planning the most effective treatment to avoid respiratory compromise. In a 10‐month‐old baby girl, who was ventilator‐dependent after successful correction of double outlet right ventricle (DORV), flexible fiberoptic bronchoscopy (FFB) revealed the new formation of postoperative airway obstruction over the right main bronchus (RMB) and obstructed right tracheal bronchus (RTB). 3D‐CT demonstrated tracheobronchial obstruction (TBO) was caused by the dilated ascending aorta (AAo) and right pulmonary artery (RPA). Sequential treatments including artery pexy of AAo and RPA and balloon dilatation (BD) of the stenotic RTB and RMB had successfully restored the airway patency. The patient was successfully weaned from ventilator 2 days after treatments and has shown no respiratory difficulty thus far. Thus, the impact of preoperative 3D‐CT on planning treatment cannot be emphasized. Pediatr Pulmonol. 2010; 45:730–733. © 2010 Wiley‐Liss, Inc.
Adiposity and low‐grade systemic inflammation modulate matrix metalloproteinase‐9 levels in Greek children with sleep apnea
Authors: Kaditis Athanasios G. , Alexopoulos Emmanouel I. , Karathanasi Anastasia , Ntamagka Georgia , Oikonomidi Smaragda , Kiropoulos Theodoros S. , Zintzaras Elias , Gourgoulianis Konstantinos
Published: May 2010

Background

Matrix metalloproteinase‐9 (MMP‐9) plasma levels correlate with C‐reactive protein (CRP) concentrations and they are both increased in adults with obstructive sleep apnea (OSA). No studies have evaluated MMP‐9 levels in children with sleep apnea and CRP is not consistently elevated in pediatric OSA. The aim of this investigation was to evaluate the association of severity of OSA, adiposity, and CRP with MMP‐9 plasma levels in Greek children.

Methods

Consecutive children with snoring who underwent polysomnography and were found to have OSA (obstructive apnea–hypopnea index—OAHI ≥ 1 episode/hr) were recruited. Subjects without OSA (OAHI < 1 episode/hr) were included for comparison. Morning plasma MMP‐9 and CRP were measured.

Results

Twenty‐nine children with moderate‐to‐severe OSA (age 5.4 ± 1.5 years; OAHI 13.9 ± 13.0 episodes/hr), 55 participants with mild OSA (6.4 ± 2.6 years; OAHI 2.4 ± 1.1 episodes/hr) and 22 subjects without OSA (6.8 ± 2.6 years; OAHI 0.6 ± 0.2 episodes/hr) were studied. Children with moderate‐to‐severe OSA were similar to those with mild OSA or without OSA regarding ln‐transformed MMP‐9 values (5.87 ± 0.60 vs. 5.84 ± 0.55 vs. 5.80 ± 0.46; P > 0.05) and CRP concentrations (0.22 ± 0.29 mg/dl vs. 0.21 ± 0.36 vs. 0.13 ± 0.16 mg/dl; P > 0.05). In multiple linear regression, body mass index (P = 0.027) and CRP levels (P = 0.008), but not OAHI or SpO2 nadir (P > 0.05), were significantly related to MMP‐9 values.

Conclusions

Adiposity and systemic inflammation unrelated to OSA severity, modulate MMP‐9 levels in Greek children. Pediatr Pulmonol. 2010; 45:693–699. © 2010 Wiley‐Liss, Inc.
Thioesterases: A new perspective based on their primary and tertiary structures
Authors: Cantu David C. , Chen Yingfei , Reilly Peter J.
Published: May 2010

Thioesterases (TEs) are classified into EC 3.1.2.1 through EC 3.1.2.27 based on their activities on different substrates, with many remaining unclassified (EC 3.1.2.–). Analysis of primary and tertiary structures of known TEs casts a new light on this enzyme group. We used strong primary sequence conservation based on experimentally proved proteins as the main criterion, followed by verification with tertiary structure superpositions, mechanisms, and catalytic residue positions, to accurately define TE families. At present, TEs fall into 23 families almost completely unrelated to each other by primary structure. It is assumed that all members of the same family have essentially the same tertiary structure; however, TEs in different families can have markedly different folds and mechanisms. Conversely, the latter sometimes have very similar tertiary structures and catalytic mechanisms despite being only slightly or not at all related by primary structure, indicating that they have common distant ancestors and can be grouped into clans. At present, four clans encompass 12 TE families. The new constantly updated ThYme (Thioester‐active enzYmes) database contains TE primary and tertiary structures, classified into families and clans that are different from those currently found in the literature or in other databases. We review all types of TEs, including those cleaving CoA, ACP, glutathione, and other protein molecules, and we discuss their structures, functions, and mechanisms.
Free fermions violate the area law for entanglement entropy
Authors: Helling R.C. , Spitzer W.
Published: May 2010

We show that the entanglement entropy associated to a region grows faster than the area of its boundary surface. This is done by proving a special case of a conjecture due to Widom that yields a surprisingly simple expression for the leading behaviour of the entanglement entropy.
Modulation of polarization field by fluorine ions in AlGaN/GaN heterostructures revealed by positron annihilation spectroscopy
Authors: Wang Maojun , Cheng Chung Choi , Beling Chris D. , Fung Stevenson , Chen Kevin J.
Published: May 2010

Modulations of energy band and polarization field by fluorine ions in fluorine plasma treated AlGaN/GaN heterostructures were revealed by positron annihilation spectroscopy (PAS). It is found that the annihilation probability is mainly governed by the electric field in the AlGaN/GaN heterostructure, which could be modulated by charged ions, opposite to what was first expected from the large number of plasma‐induced defects such as Ga‐vacancies. The modulation of electric field is successfully observed through the opposite changes in the S parameters on the two sides of the hetero‐interface after fluorine plasma treatment due to the opposite E‐field directions. Fluorine is experimentally proved to be negatively charged in GaN related materials, which is consistent with the operation principle of enhancement‐mode AlGaN/GaN HEMT fabricated by fluorine plasma treatment. It is also suggested that PAS is a useful tool to probe the intrinsic electric field in AlGaN/GaN system.
Impact of n‐type doping on the terahertz surface emission from c‐plane InN
Authors: Polyakov V. M. , Cimalla V. , Lebedev V. , Schwierz F.
Published: May 2010

We theoretically investigate the influence of n‐type doping on the terahertz (THz) electric field emission from unbiased c‐plane InN surfaces using the ensemble Monte Carlo (MC) method. It is shown that the increase of n‐type doping has twofold effect on the THz surface emission. The detrimental effect of electron drift mobility decrease is compensated by doping‐derived electrons constructively contributing to the total dynamic dipole responsible for a generation of the THz electric field pulse emission from InN surface.
Determination of the valence band offsets at HfO2/InN(0001) and InN/In0.3Ga0.7N(0001) heterojunctions using X‐ray photoelectron spectroscopy
Authors: Eisenhardt Anja , Knübel Andreas , Schmidt Ralf , Himmerlich Marcel , Wagner Joachim , Schaefer Juergen A. , Krischok Stefan
Published: May 2010

The valence band offset (VBO) at a InN/In0.3Ga0.7N(0001) as well as HfO2/InN(0001) heterojunction is investigated by X‐ray photoelectron spectroscopy using monochromated AlKα radiation. The InN and In0.3Ga0.7N films were grown using plasma‐assisted molecular beam epitaxy, whereas HfO2 layers were deposited by plasma‐assisted electron beam evaporation. The VBOs were determined by analysing the core level binding energy and valence band maxima of bulk‐like films as well as of In0.3Ga0.7N and InN layers covered with 5 nm thick overlayers of InN and HfO2, respectively. The resulting VBO values are ∼0.5 eV for the InN/In0.3Ga0.7N heterojunction and ∼0.9 eV in the case of the HfO2/InN heterointerface.
MOVPE growth and optical characterization of InGaAsN T‐shaped quantum wires lattice‐matched to GaAs
Authors: Klangtakai Pawinee , Sanorpim Sakuntam , Katayama Ryuji , Onabe Kentaro
Published: May 2010

InGaAsN T‐shaped quantum wire (T‐QWR) lattice‐matched to GaAs was grown by metal organic vapour‐phase epitaxy (MOVPE) and its optical property was investigated. The InGaAsN T‐QWR was observed at the intersection of two InGaAsN quantum wells (QWs) on (001) and (110) surfaces, namely QW1 and QW2, respectively. In, N contents and well‐thickness in QW1 and QW2 were determined by high resolution X‐ray diffraction (HRXRD). Photoluminescence (PL) was taken to obtain excitonic states in the one‐dimensional T‐QWR as well as QW1 and QW2. High PL intensity reveals an achievement of high quality T‐QWR. At low‐temperature, InGaAsN T‐QWR exhibits an emission at around 1.141 eV with a large lateral confinement of about 61 and 99 meV for QW1 and QW2, respectively. This method for producing InGaAsN T‐QWR may be useful for optical or electronic device applications.
Stress relaxed nanoepitaxy GaN for growth of phosphor‐free indium‐rich nanostructures incorporated in apple‐white LEDs
Authors: Soh C. B. , Liu W. , Chua S. J. , Ang N. S. S. , Yong A. M. , Lai S. C. , Teng J. H.
Published: May 2010

Phosphor‐free apple‐white light emitting diodes (LEDs) have been fabricated using dual stacked InGaN/GaN multiple quantum wells (MQWs) comprising a lower set of long wavelength emitting indium rich nanostructures incorporated in MQWs with an upper set of cyan‐green emitting MQWs. The LEDs were grown on nano‐epitaxial lateral overgrown (ELO) GaN template formed by regrowth of GaN over SiO2 film patterned using an anodic alumina oxide mask with holes of ∼125 nm diameter and a period of 250 nm. The MQWs grown on the nano‐ELO GaN templates show stronger photoluminescence intensity and a higher activation energy for their peak emission. A minimal shift in the electroluminescence (EL) spectra with higher injection current applied for LEDs grown on ELO‐GaN compared to conventional GaN template, suggests a reduction in strain of the quantum well layers on the nano‐ELO GaN template. An enhancement in the light extraction efficiency is also achieved with multiple scattering via the embedded SiO2 mask.
Various misfit dislocations in green and yellow GaInN/GaN light emitting diodes
Authors: Zhu Mingwei , You Shi , Detchprohm Theeradetch , Paskova Tanya , Preble Edward A. , Wetzel Christian
Published: May 2010

We report the growth and structural characteristics of green and yellow (529–576 nm) GaInN/GaN light emitting diodes (LEDs) grown on two types of c‐plane substrates – bulk GaN and sapphire. In this longer wavelength range, depending on the substrate, we find different strain relaxation mechanisms within the GaInN/GaN quantum well (QW) region. In optimized epitaxy, structures on sapphire that contain a low density of threading dislocations (TDs) within the n‐GaN show virtually no generation of additional misfit dislocations (MDs) (<108 cm−2) or V‐defects within the QW region for emission wavelengths up to 571 nm. On bulk GaN substrate, however, where much fewer TDs reach the QWs, strain relaxation is observed by inclined dislocation pairs in green emitters and a high density of edge‐type MDs in yellow emitters. The electroluminescence line width, as well as the efficiency droop, was found to increase with dislocation density in the QWs.
A novel Gymnema sylvestre extract stimulates insulin secretion from human islets in vivo and in vitro
Authors: Al‐Romaiyan A. , Liu B. , Asare‐Anane H. , Maity C. R. , Chatterjee S. K. , Koley N. , Biswas T. , Chatterji A. K. , Huang G‐C. , Amiel S. A. , Persaud S. J. , Jones P. M.
Published: May 2010

Many plant‐based products have been suggested as potential antidiabetic agents, but few have been shown to be effective in treating the symptoms of Type 2 diabetes mellitus (T2DM) in human studies, and little is known of their mechanisms of action. Extracts of Gymnema sylvestre (GS) have been used for the treatment of T2DM in India for centuries. The effects of a novel high molecular weight GS extract, Om Santal Adivasi, (OSA®) on plasma insulin, C‐peptide and glucose in a small cohort of patients with T2DM are reported here. Oral administration of OSA® (1 g/day, 60 days) induced significant increases in circulating insulin and C‐peptide, which were associated with significant reductions in fasting and post‐prandial blood glucose. In vitro measurements using isolated human islets of Langerhans demonstrated direct stimulatory effects of OSA® on insulin secretion from human ?‐cells, consistent with an in vivo mode of action through enhancing insulin secretion. These in vivo and in vitro observations suggest that OSA® may provide a potential alternative therapy for the hyperglycemia associated with T2DM. Copyright © 2010 John Wiley & Sons, Ltd.
High‐throughput metabolic stability studies in drug discovery by orthogonal acceleration time‐of‐flight (OATOF) with analogue‐to‐digital signal capture (ADC)
Authors: Temesi David G. , Martin Scott , Smith Robin , Jones Christopher , Middleton Brian
Published: May 2010

Screening assays capable of performing quantitative analysis on hundreds of compounds per week are used to measure metabolic stability during early drug discovery. Modern orthogonal acceleration time‐of‐flight (OATOF) mass spectrometers equipped with analogue‐to‐digital signal capture (ADC) now offer performance levels suitable for many applications normally supported by triple quadruple instruments operated in multiple reaction monitoring (MRM) mode. Herein the merits of MRM and OATOF with ADC detection are compared for more than 1000 compounds screened in rat and/or cryopreserved human hepatocytes over a period of 3 months. Statistical comparison of a structurally diverse subset indicated good agreement for the two detection methods. The overall success rate was higher using OATOF detection and data acquisition time was reduced by around 20%. Targeted metabolites of diazepam were detected in samples from a CLint determination performed at 1 µM. Data acquisition by positive and negative ion mode switching can be achieved on high‐performance liquid chromatography (HPLC) peak widths as narrow as 0.2 min (at base), thus enabling a more comprehensive first pass analysis with fast HPLC gradients. Unfortunately, most existing OATOF instruments lack the software tools necessary to rapidly convert the huge amounts of raw data into quantified results. Software with functionality similar to open access triple quadrupole systems is needed for OATOF to truly compete in a high‐throughput screening environment. Copyright © 2010 John Wiley & Sons, Ltd.
Thin‐layer chromatography and mass spectrometry coupled using proximal probe thermal desorption with electrospray or atmospheric pressure chemical ionization
Authors: Ovchinnikova Olga S. , Van Berkel Gary J.
Published: May 2010

An atmospheric pressure proximal probe thermal desorption sampling method coupled with secondary ionization by electrospray or atmospheric pressure chemical ionization was demonstrated for the mass spectrometric analysis of a diverse set of compounds (dyestuffs, pharmaceuticals, explosives and pesticides) separated on various high‐performance thin‐layer chromatography plates. Line scans along or through development lanes on the plates were carried out by moving the plate relative to a stationary heated probe positioned close to or just touching the stationary phase surface. Vapors of the compounds thermally desorbed from the surface were drawn into the ionization region of a combined electrospray ionization/atmospheric pressure chemical ionization source where they merged with reagent ions and/or charged droplets from a corona discharge or an electrospray emitter and were ionized. The ionized components were then drawn through the atmospheric pressure sampling orifice into the vacuum region of a triple quadrupole mass spectrometer and detected using full scan, single ion monitoring, or selected reaction monitoring mode. Studies of variable parameters and performance metrics including the proximal probe temperature, gas flow rate into the ionization region, surface scan speed, read‐out resolution, detection limits, and surface type are discussed. Published in 2010 by John Wiley & Sons, Ltd.
Comparison of analytical approaches for liquid chromatography/mass spectrometry determination of the alcohol biomarker ethyl glucuronide in urine
Authors: Helander Anders , Kenan Naama , Beck Olof
Published: May 2010

Official guidelines originating from a European Union directive regulate requirements for analytical methods used to identify chemical compounds in biological matrices. This study compared different liquid chromatography/electropray ionization mass spectrometry (LC/ESI‐MS) and tandem mass spectrometry (LC/ESI‐MS/MS) procedures for accurate determination of the conjugated ethanol metabolite and alcohol biomarker ethyl glucuronide (EtG) in urine, and the value of combined EtG and ethyl sulfate (EtS) measurement. Analysis was carried out on 482 urines following solid‐phase extraction (SPE) sample cleanup or using direct injection of a diluted sample. SPE combined with LC/MS/MS was demonstrated to be the most selective and sensitive method and was chosen as reference method. The EtG results by different methods showed good correlation (r = 0.96–0.98). When comparing five reporting limits for EtG in the range 0.10–1.00 mg/L, the overall agreement with the reference method (frequency of true positives plus true negatives) was 82–97% for direct‐injection LC/MS/MS, 90–97% for SPE‐LC/MS, 86–98% for direct‐injection LC/MS, and 86–98% for direct‐injection LC/MS analysis of EtG and EtS. Most deviations were attributable to uncertainty in quantitation, when the value was close to a cutoff but the respective results were slightly above and below, or vice versa, the critical limit. However, for direct‐injection LC/MS/MS, despite earning 4 identification points, equally many negative results were due to a product ion ratio outside the ±20% deviation accepted by the guidelines. These results indicate that the likelihood of different analytical methods to provide reliable analytical results depends on the reporting limit applied. Copyright © 2010 John Wiley & Sons, Ltd.
Testing the use of septum‐capped vials for 13C‐isotope abundance analysis of carbon dioxide
Authors: Hardie S. M. L. , Garnett M. H. , Fallick A. E. , Stott A. W. , Rowland A. P. , Ostle N. J.
Published: May 2010

Studying ecosystem processes in the context of carbon cycling and climate change has never been more important. Stable carbon isotope studies of gas exchange within terrestrial ecosystems are commonly undertaken to determine sources and rates of carbon cycling. To this end, septum‐capped vials (‘Exetainers’) are often used to store samples of CO2 prior to mass spectrometric analysis. To evaluate the performance of such vials for preserving the isotopic integrity (δ13C) and concentration of stored CO2 we performed a rigorous suite of tests. Septum‐capped vials were filled with standard gases of varying CO2 concentrations (∼700 to 4000 ppm), δ13C values (approx. −26.5 to +1.8‰V‐PDB) and pressures (33 and 67% above ambient), and analysed after a storage period of between 7 and 28 days. The vials performed well, with the vast majority of both isotope and CO2 concentration results falling within the analytical uncertainty of chamber standard gas values. Although the study supports the use of septum‐capped vials for storing samples prior to mass spectrometric analysis, it does highlight the need to ensure that sampling chamber construction is robust (air‐tight). Copyright © 2010 John Wiley & Sons, Ltd.
Isomer differentiation via collision‐induced dissociation: The case of protonated α‐, β2‐ and β3‐phenylalanines and their derivatives
Authors: Lam Adrian K. Y. , O'Hair Richard A. J.
Published: May 2010

A combination of electrospray ionisation (ESI), multistage and high‐resolution mass spectrometry experiments is used to examine the gas‐phase fragmentation reactions of the three isomeric phenylalanine derivatives, α‐phenylalanine, β2‐phenylalanine and β3‐phenylalanine. Under collision‐induced dissociation (CID) conditions, each of the protonated phenylalanine isomers fragmented differently, allowing for differentiation. For example, protonated β3‐phenylalanine fragments almost exclusively via the loss of NH3, only β2‐phenylalanine via the loss of H2O, while α‐ and β2‐phenylalanine fragment mainly via the combined losses of H2O + CO. Density functional theory (DFT) calculations were performed to examine the competition between NH3 loss and the combined losses of H2O and CO for each of the protonated phenylalanine isomers. Three potential NH3 loss pathways were studied: (i) an aryl‐assisted neighbouring group; (ii) 1,2 hydride migration; and (iii) neighbouring group participation by the carboxyl group. Finally, we have shown that isomer differentiation is also possible when CID is performed on the protonated methyl ester and methyl amide derivatives of α‐, β2‐ and β3‐phenylalanines. Copyright © 2010 John Wiley & Sons, Ltd.
Bayesian learning theory applied to human cognition
Authors: Jacobs Robert A. , Kruschke John K.
Published: May 2010

Probabilistic models based on Bayes' rule are an increasingly popular approach to understanding human cognition. Bayesian models allow immense representational latitude and complexity. Because they use normative Bayesian mathematics to process those representations, they define optimal performance on a given task. This article focuses on key mechanisms of Bayesian information processing, and provides numerous examples illustrating Bayesian approaches to the study of human cognition. We start by providing an overview of Bayesian modeling and Bayesian networks. We then describe three types of information processing operations—inference, parameter learning, and structure learning—in both Bayesian networks and human cognition. This is followed by a discussion of the important roles of prior knowledge and of active learning. We conclude by outlining some challenges for Bayesian models of human cognition that will need to be addressed by future research.WIREs Cogn Sci2011 2 8–21 DOI: 10.1002/wcs.80

This article is categorized under:

Computer Science > Artificial Intelligence

Psychology > Learning
The Surgical Strategy and the Molecular Analysis of Patients with Parathyroid Cancer
Authors: Enomoto Keisuke , Uchino Shinya , Ito Akiko , Watanabe Shin , Shibuya Hiroshi , Enomoto Yukie , Noguchi Shiro
Published: May 2010

Background

Parathyroid cancer is a rare endocrine tumor, and the prognostic factors for this cancer remain unclear. The standard therapy is en bloc resection of the primary tumor at the time of the initial operation. However, the clinical significance of prophylactic neck dissection (PND) in the management of parathyroid cancer has not yet been established. In this study, we investigated its clinical significance in patients with parathyroid cancer and the association of gene mutations with tumor progression.

Methods

A total of 12 patients with parathyroid cancer were treated and have been followed at Noguchi Thyroid Clinic and Hospital Foundation since 1977. In all, 11 patients were treated with the initial surgery for the cancer, and 1 patient underwent surgery for a metastatic lung lesion. Somatic and germ‐line mutations of the HRPT2 and MEN1 were examined by polymerase chain reaction and automated DNA sequencing.

Results

En bloc resections of thyroid tissue were performed in 10 patients, and 1 patient underwent only parathyroidectomy with limited resection of the thyroid gland. PND was performed in eight patients, and no lymph node metastases were found in the histological specimens. Six of the eight patients had no evidence of the disease, and two had recurring disease (neck lymph node and lung in one patient and local, lung, and brain in another). PND was not performed in three patients, two of whom had no evidence of the disease and one with recurrence at the site of a regional lymph node. There were no significant differences in disease‐free survival and cause‐specific survival between the patients who underwent PND and the patients who did not (P = 0.98 and P = 0.32, respectively). Among the 12 patients with parathyroid cancer, 1 had a germ‐line mutation of the HRPT2 at exon 7, codon 234, CGA (Arg) to TGA (Stop), and 1 patient had a tumor‐specific mutation at exon 1, nucleotide 34–37 delAACA. Two of the four patients with recurrent disease had an HRPT2 gene mutation. MEN1 gene analysis revealed one somatic missense mutation at exon 2, codon 121, GTC (Val) to GAC (Asp) in one patient.

Conclusions

PND for patients with parathyroid cancer resulted in no evidence of lymph node metastasis and does not improve the prognosis. HRPT2 gene mutation may be associated with tumor recurrence.
Aminoacylase 1 deficiency associated with autistic behavior
Authors: Tylki‐Szymanska Anna , Gradowska Wanda , Sommer Anke , Heer Angelina , Walter Melanie , Reinhard Christina , Omran Heymut , Sass Jörn Oliver , Jurecka Agnieszka
Published: May 2010

Aminoacylase 1 (ACY1) deficiency is a recently described inborn error of metabolism. Most of the patients reported so far have presented with rather heterogeneous neurologic symptoms. At this moment, it is not clear whether ACY1 deficiency represents a true metabolic disease with a causal relationship between the enzyme defect and the clinical phenotype or merely a biochemical abnormality. Here we present a patient identified in the course of selective screening for inborn errors of metabolism (IEM). The patient was diagnosed with autistic syndrome and admitted to the Children's Memorial Health Institute (CMHI) for metabolic evaluation. Organic acid analysis using gas chromatography–mass spectrometry (GC‐MS) revealed increased urinary excretion of several N‐acetylated amino acids, including the derivatives of methionine, glutamic acid, alanine, glycine, leucine, isoleucine, and valine. In Epstein‐Barr virus (EBV)‐transformed lymphoblasts, ACY1 activity was deficient. The mutation analysis showed a homozygous c.1057C>T transition, predicting a p.Arg353Cys substitution. Both parents were heterozygous for the mutation and had normal results in the organic acid analysis using GC‐MS. This article reports the findings of an ACY1‐deficient patient presenting with autistic features.