bluuebunny/crossref_metadata_2025 huggingface dataset:
Measurement of evaporation from the forest floor in a deciduous forest throughout the year using microlysimeter and closed‐chamber systems
Authors: Deguchi Aiko , Hattori Shigeaki , Daikoku Kenichi , Park Ho‐Teak
Published: April 2008

Evaporation from the forest floor (EFF) in a deciduous broadleaf forest was measured using microlysimeter and closed‐chamber systems. The microlysimeter was used at six points in the experimental basin, and measurements gave different EFF values at different points. This could be attributed to the local photoenvironment of each sampling point, rather than to litter conditions, if the spatial variation in air temperature (Ta) or vapour pressure deficit (VPD) at the forest floor was small within this basin. A detachable microlysimeter measured condensation in the litter layer during the night, indicating that the litter layer, as well as the mulch layer, played a role in preventing evaporation from the soil layer. The closed‐chamber system made it possible to continuously measure long‐term EFF. EFF was closely related to VPD; even during the night, when solar radiation was zero, EFF amounted to 14·0% of the daily EFF. The daily EFF was 0·20 ± 0·13 mm day−1 during the study period, with two seasonal peaks: in late spring (0·31 mm day−1 in April) and early fall (0·22 mm day−1 in September). The former peak has been reported from two deciduous forests in Japan and is strongly related to the solar radiation reaching the forest floor when the trees are dormant. Copyright © 2008 John Wiley & Sons, Ltd.
Diffusion of treatment research: does open access matter?
Authors: Hardisty David J. , Haaga David A. F.
Published: April 2008

Advocates of the Open Access movement claim that removing access barriers will substantially increase the diffusion of academic research. If successful, this movement could play a role in efforts to increase utilization of psychotherapy research by mental health practitioners. In a pair of studies, mental health professionals were given either no citation, a normal citation, a linked citation, or a free access citation and were asked to find and read the cited article. After 1 week, participants read a vignette on the same topic as the article and gave recommendations for an intervention. In both studies, those given the free access citation were more likely to read the article, yet only in one study did free access increase the likelihood of making intervention recommendations consistent with the article. © 2008 Wiley Periodicals, Inc. J Clin Psychol/In Session 64: 1–19, 2008.
Cr:Forsterite‐laser‐based fiber‐optic nonlinear endoscope with higher efficiencies
Authors: Chan Ming‐Che , Chu Shi‐Wei , Tseng Chien‐Hung , Wen Yu‐Chieh , Chen Yi‐Hsien , Su Guo‐Dung John , Sun Chi‐Kuang
Published: April 2008

We demonstrate a beam‐scanning nonlinear light endoscope based on a flexible fiber bundle. Excited with a femtosecond Cr:Forsterite laser, the degradation in multiphoton multiharmonic excitation efficiency due to the pulse‐broadening effect is significantly reduced without utilizing any external devices. The system resolution has been characterized to be 5.4 μm in the two‐photon fluorescence endoscope, limited by the sampling theory. Finally, several image examples have been given. Microsc. Res. Tech., 2008. © 2008 Wiley‐Liss, Inc.
MR‐guided core biopsy with MR fluoroscopy using a short, wide‐bore 1.5‐Tesla scanner: Feasibility and initial results
Authors: Stattaus Joerg , Maderwald Stefan , Forsting Michael , Barkhausen Joerg , Ladd Mark E.
Published: April 2008

Purpose

To evaluate MR fluoroscopy in a short, wide‐bore 1.5T MRI suitable for near real‐time biopsy guidance.

Materials and Methods

A total of eight consecutive patients underwent MR‐guided core biopsy in a 1.5T system with a 70 cm bore diameter. A total of five biopsies were performed in focal liver lesions, three biopsies in soft‐tissue tumors. Before biopsy, three different fast MR sequences were compared for image quality (anatomical visibility, lesion visibility, and artifacts), and signal‐to‐noise ratio (SNR) and contrast‐to‐noise ratio (CNR) were calculated. In all cases, an MR‐compatible guidance needle was positioned under MR fluoroscopy using the most suitable sequence.

Results

In each patient the guidance needle could be placed accurately under MR fluoroscopy without having to remove the patient from the isocenter of the magnet during needle movement. All biopsies were technically successful and appropriate specimens could be obtained. In prebiopsy imaging, a T2‐weighted single shot turbo spinecho sequence (half‐Fourier acquisition single‐shot turbo spin‐echo [HASTE]) achieved the best rating for lesion visibility and superior SNR and CNR values.

Conclusion

Findings of this study demonstrate that MR fluoroscopy for biopsy guidance in a short, wide‐bore 1.5T scanner is feasible. This scanner combines the patient access advantages of an open‐bore system with the superior image quality and speed of a high‐field scanner. In our series, the HASTE sequence was best suited for MR‐guidance of biopsies. J. Magn. Reson. Imaging 2008;27:1181–1187. © 2008 Wiley‐Liss, Inc.
MRI abnormalities in normal‐appearing brain tissue of treated adult PKU patients
Authors: Ding Xiao‐Qi , Fiehler Jens , Kohlschütter Brigitte , Wittkugel Oliver , Grzyska Ulrich , Zeumer Hermann , Ullrich Kurt
Published: April 2008

Purpose

To detect possible subclinical pathological brain changes a study on adult phenylketonuria (PKU) patients by using quantitative MRI methods was performed, since neuropsychological and cognitive deficits in treated patients with PKU have not yet been shown to correlate clearly with the brain lesions identified by conventional MRI.

Materials and Methods

Eight subjects, four PKU patients with well‐documented dietary treatment and four age‐ and sex‐matched adult controls, underwent MRI, including a triple echo sequence and a diffusion tensor imaging sequence. Brain maps of T2 relaxation time (T2), relative proton density (PD), and fractional anisotropy (FA) as well as apparent diffusion coefficient (ADC) were derived for each subject. T2, PD, FA, and ADC were measured in 22 predefined regions of gray matter (GM) and white matter (WM) on the corresponding maps, and compared with those of four age‐matched healthy adult controls.

Results

In addition to a prolonged T2 value measured in affected WM, as expected, we observed a significant shortening of the T2 relaxation time and reduction of ADC in normal‐appearing brain tissue and an increased proton density in both GM and WM of the patients. No differences were observed in FA values between controls and patients.

Conclusion

Repeatedly reduced T2 relaxation time, ADC, and increased proton density without changes in FA indicate a higher cell‐packing density in normal‐appearing brain without changes in the directedness of fibers. These structural changes may be related to neuropsychological and cognitive deficits in treated PKU patients. J. Magn. Reson. Imaging 2008;27:998–1004. © 2008 Wiley‐Liss, Inc.
Contribution of cardiac‐induced brain pulsation to the noise of the diffusion tensor in Turboprop diffusion tensor imaging (DTI)
Authors: Gui Minzhi , Tamhane Ashish A. , Arfanakis Konstantinos
Published: April 2008

Purpose

To assess the effects of cardiac‐induced brain pulsation on the noise of the diffusion tensor in Turboprop (a form of periodically rotated overlapping parallel lines with enhanced reconstruction [PROPELLER] imaging) diffusion tensor imaging (DTI).

Materials and Methods

A total of six healthy human subjects were imaged with cardiac‐gated as well as nongated Turboprop DTI. Gated and nongated Turboprop DTI datasets were also simulated using actual data acquired exclusively during the diastolic or systolic period of the cardiac cycle. The total variance of the diffusion tensor (TVDT) was measured and compared between acquisitions.

Results

The TVDT near the ventricles was significantly reduced in cardiac‐gated compared to nongated Turboprop DTI acquisitions. Furthermore, the effects of brain pulsation were reduced, but not eliminated, when increasing the amount of data collected. Finally, data corrupted by cardiac‐induced pulsation were not consistently detected by the step of the conventional Turboprop reconstruction algorithm that evaluates the quality of data in different blades. Thus, the inherent quality weighting of the conventional Turboprop reconstruction algorithm was unable to compensate for the increased noise in the diffusion tensor due to brain pulsation.

Conclusion

Cardiac‐induced brain pulsation increases the TVDT in Turboprop DTI. Use of cardiac gating to limit data acquisition to the diastolic period of the cardiac cycle reduces the TVDT at the expense of imaging time. J. Magn. Reson. Imaging 2008;27:1164–1168. © 2008 Wiley‐Liss, Inc.
Pressure effects in lutetium yttrium oxyorthosilicate single crystals
Authors: Ricci Pier Carlo , Chiriu Daniele , Carbonaro Carlo Maria , Desgreniers Serge , Fortin Emery , Anedda Alberto
Published: April 2008

The Raman scattering from Lu1.8Y0.2SiO5 single crystals was investigated for quasi‐hydrostatic pressures ranging from atmospheric to about 15 GPa at room temperature. The material, originally belonging to the monoclinic C2/c structure, transforms gradually to a higher‐density phase upon the application of pressure. Unit cell volume, peak position, and the Grüneisen parameter have been calculated and analyzed, revealing three different pressure regimes. The first low‐pressure regime relates mainly to the change of unit cell volume. In the second pressure regime, the gradual phase transformation starts at about 3 GPa and is completed at a pressure of 10 GPa. The third pressure regime part reveals a sensibly lower pressure dependence. A detailed analysis of the data allowed us to propose a scheme for a pressure‐induced gradual phase transition, resulting in the coexistence of phases over a wide pressure range. Moreover, the material reverts to the ambient‐condition phase upon release of pressure, showing an almost total reversibility. By comparison with the vibrational spectra of the pure Y2SiO5 compound and from the analysis of the crystal structures, the pressure‐induced high‐density phase is assigned to the P21/c monoclinic structure, typical of oxyorthosilicates. Copyright © 2008 John Wiley & Sons, Ltd.
Time‐resolved resonance Raman and density functional theory study of the deprotonation reaction of the triplet state of para‐hydroxybenzophenone in mixed acetonitrile/water solutions
Authors: Du Yong , Xue Jiadan , Ma Chensheng , Ming Kwok Wai , Lee Phillips David
Published: April 2008

Nanosecond time‐resolved resonance Raman (ns‐TR3) spectroscopy was employed to investigate the triplet state of para‐hydroxybenzophenone (p‐hBP) in pure acetonitrile (MeCN) and its subsequent deprotonation reaction in a H2O/MeCN mixed solution. The TR3 results reveal that the deprotonation reaction occurred with the p‐hBP triplet state as the precursor species after 266 nm photolysis of p‐hBP in a H2O/MeCN mixed solution. The ground‐state p‐hBP anion species was observed to form about 20 ns after excitation in a 5% H2O/95% MeCN mixed solvent. Density functional theory (DFT) calculations were done to help obtain information about the structures and vibrational modes of the triplet p‐hBP and p‐hBP anion species. A reaction scheme is proposed for the photoreaction pathways of p‐hBP in pure MeCN and H2O/MeCN mixed solvents. Comparison of the results here for p‐hBP to the related para‐hydroxyacetophenone (HA) system indicates that substitution of the methyl group in HA with a phenyl group to form p‐hBP significantly alters the chemical reactivity of the triplet state so that both deprotonation and intersystem crossing (ISC) for the triplet state occur much faster in p‐hBP than in HA. Copyright © 2008 John Wiley & Sons, Ltd.
Plasmon‐enhanced polarized Raman spectroscopy for sensitive surface characterization
Authors: Kasim J. , Tee X. Y. , You Y. M. , Ni Z. H. , Setiawan Y. , Lee P. S. , Chan L. , Shen Z. X.
Published: April 2008

Local‐mode and localized surface plasmons generated on the silver thin film can selectively enhance the Raman signal from the surface. Further improvement of surface signal can be obtained by using the polarized Raman technique that results in a dramatic enhancement of the surface sensitivity by up to 25.4 times as compared to that without a silver coating. This technique will be very useful for Raman study on samples that suffer overlapping background signal. In this article, we show that it can be used to significantly improve the signal of thin strained‐Si layer on top of SiGe buffer layer. Copyright © 2008 John Wiley & Sons, Ltd.
Fatty acid and fat‐soluble antioxidant concentrations in milk from high‐ and low‐input conventional and organic systems: seasonal variation
Authors: Butler Gillian , Nielsen Jacob H , Slots Tina , Seal Chris , Eyre Mick D , Sanderson Roy , Leifert Carlo
Published: April 2008

BACKGROUND: Previous studies showed differences in fatty acid (FA) and antioxidant profiles between organic and conventional milk. However, they did not (a) investigate seasonal differences, (b) include non‐organic, low‐input systems or (c) compare individual carotenoids, stereoisomers of α‐tocopherol or isomers of conjugated linoleic acid. This survey‐based study compares milk from three production systems: (i) high‐input, conventional (10 farms); (ii) low‐input, organic (10 farms); and (iii) low‐input non‐organic (5 farms). Samples were taken during the outdoor grazing (78 samples) and indoor periods (31 samples).

RESULTS: During the outdoor grazing period, on average, milk from the low‐input systems had lower saturated FAs, but higher mono‐ and polyunsaturated FA concentrations compared with milk from the high‐input system. Milk from both the low‐input organic and non‐organic systems had significantly higher concentrations of nutritionally desirable FAs and antioxidants—conjugated linoleic (60% and 99%, respectively) and α‐linolenic (39% and 31%, respectively) acids, α‐tocopherol (33% and 50%, respectively) and carotenoids (33% and 80%, respectively)—compared with milk from the high‐input system. Milk composition differed significantly between the two low‐input systems during the second half of the grazing period only; with milk from non‐organic cows being higher in antioxidants, and conjugated linoleic acid, and that from organic cows in α‐linolenic acid. In contrast, few significant differences in composition were detected between high‐input and low‐input organic systems when cows were housed.

CONCLUSIONS: Milk composition is affected by production systems by mechanisms likely to be linked to the stage and length of the grazing period, and diet composition, which will influence subsequent processing, and sensory and potential nutritional qualities of the milk. Copyright © 2008 Society of Chemical Industry
Diagnosis and management of desmoid tumors and fibrosarcoma
Authors: Wong Sandra L.
Published: April 2008

Fibrous tumors represent a diverse subtype of soft tissue tumors and can represent benign conditions as well as frankly malignant sarcomas. Desmoid tumors and dermatofibrosarcoma protuberans are more difficult to classify and tend to be considered in the intermediate risk category. They are distinct entities, but both are locally aggressive processes which are plagued with attendant morbidity and high recurrence rates. Complete surgical resection is the mainstay of treatment. J. Surg. Oncol. 2008;97:554–558. © 2008 Wiley‐Liss, Inc.
Comparative study among different neural net learning algorithms applied to rainfall time series
Authors: Chattopadhyay Surajit , Chattopadhyay Goutami
Published: April 2008

The present article reports studies to identify a non‐linear methodology to forecast the time series of average summer‐monsoon rainfall over India. Three advanced backpropagation neural network learning rules namely, momentum learning, conjugate gradient descent (CGD) learning, and Levenberg–Marquardt (LM) learning, and a statistical methodology in the form of asymptotic regression are implemented for this purpose. Monsoon rainfall data pertaining to the years from 1871 to 1999 are explored. After a thorough skill comparison using statistical procedures the study reports the potential of CGD as a learning algorithm for the backpropagation neural network to predict the said time series. Copyright © 2008 Royal Meteorological Society
Expression profile of male germ cell‐associated genes in mouse embryonic stem cell cultures treated with all‐trans retinoic acid and testosterone
Authors: Silva Celso , Wood Jennifer R. , Salvador Lisa , Zhang Zhibing , Kostetskii Igor , Williams Carmen J. , Strauss Jerome F.
Published: April 2008

Cells that morphologically and functionally resemble male germ cells can be spontaneously derived from ES cells. However, this process is inefficient and unpredictable suggesting that the expression pattern of male germ cell associated genes during spontaneous ES cell differentiation does not mimic the in vivo profiles of the genes. Thus, in the present study, the temporal profile of genes expressed at different stages of male germ cell development was examined in differentiating ES cells. The effect of all‐trans retinoic acid (RA) which is a known inducer of primordial germ cell (PGC) proliferation/survival in vitro and testosterone which is required for spermatogenesis in vivo on the expression of these genes was also determined. Each of the 12 genes analyzed exhibited one of four temporal expression patterns in untreated differentiating ES cells: progressively decreased (Dppa3, Sycp3, Msy2), initially low and then increased (Stra8, Sycp1, Dazl, Act, Prm1), initially decreased and then increased (Piwil2, Tex14), or relatively unchanged (Akap3, Odf2). RA‐treated cells exhibited increased expression of Stra8, Dazl, Act, and Prm1 and suppressed expression of Dppa3 compared to untreated controls. Furthermore, testosterone increased expression of Stra8 while the combination of RA and testosterone synergistically increased expression of Act. Our findings establish a comprehensive profile of male germ cell gene expression during spontaneous differentiation of murine ES cells and describe the capacity of RA and testosterone to modulate the expression of these genes. Furthermore, these data represent an important first step in designing a plausible directed differentiation protocol for male germ cells. Mol. Reprod. Dev. 76: 11–21, 2009. © 2008 Wiley‐Liss, Inc.
The timing of insulin administration to hospital inpatients is unsafe: patient self‐administration may make it safer
Authors: Gangopadhyay KK , Ebinesan AD , Mtemererwa B , Marshall C , Mcgettigan AT , Cope A , Narendran P
Published: April 2008

It is routine practice for insulin to be administered by hospital staff to diabetic inpatients who would normally self‐inject at home. The accuracy of this practice has not been clearly evaluated. Our audit aimed to evaluate the accuracy of insulin administration times, patient preference and the possibility of self‐administration by hospitalised patients.

Information on patient preferences, and the timing of meals and insulin administration, was collected for insulin‐treated diabetic inpatients whose insulin was administered by hospital staff (Group 1), and for another group whose insulin was self‐administered (Group 2).

In Group 1 (175 meals, 25 patients), only 19% of insulin administration times were deemed accurate. In this Group, 15/21 patients wanted to self‐inject in hospital. In Group 2 (10 patients, 73 meals), the timing of 57/73 (78%) insulin self‐administrations was accurate, and the remaining errors were often not through patient fault.

The timing of insulin administration to hospitalised patients needs to be improved. An option may be to allow selected patients to self‐administer their insulin. Copyright © 2008 John Wiley & Sons.
Comparison of the extracellular proteomes of Escherichia coli B and K‐12 strains during high cell density cultivation
Authors: Xia Xiao‐Xia , Han Mee‐Jung , Lee Sang Yup , Yoo Jong‐Shin
Published: April 2008

Escherichia coli BL21 (DE3) and W3110 strains, belonging to the family B and K‐12, respectively, have been most widely employed for recombinant protein production. During the excretory production of recombinant proteins by high cell density cultivation (HCDC) of these strains, other native E. coli proteins were also released. Thus, we analyzed the extracellular proteomes of E. coli BL21 (DE3) and W3110 during HCDC. E. coli BL21 (DE3) released more than twice the amount of protein compared with W3110 during HCDC. A total of 204 protein spots including 83 nonredundant proteins were unambiguously identified by 2‐DE and MS. Of these, 32 proteins were conserved in the two strains, while 20 and 33 strain‐specific proteins were identified for E. coli BL21 (DE3) and W3110, respectively. More than 70% of identified proteins were found to be of periplasmic origin. The outer membrane proteins, OmpA and OmpF, were most abundant. Two strains showed much different patterns in their released proteins. Also, cell density‐dependent variations in the released proteins were observed in both strains. These findings summarized as reference proteome maps will be useful for studying protein release in further detail, and provide new strategies for enhanced excretory production of recombinant proteins.
A short peptide is a protein kinase C (PKC) α‐specific substrate
Authors: Kang Jeong‐Hun , Asai Daisuke , Yamada Satoshi , Toita Riki , Oishi Jun , Mori Takeshi , Niidome Takuro , Katayama Yoshiki
Published: April 2008

The purpose of this study was to find protein kinase C (PKC) isozyme‐specific peptides. A peptide library containing 1772 sequences was designed using Scansite and screened by MALDI‐TOF MS and kinase activity assays for PKC isozyme‐specificity. A peptide (Alphatomega; H‐FKKQGSFAKKK‐NH2) with high specificity for PKCα relative to other isozymes was identified. The peptide was phosphorylated to a greater extent by tissue lysates from B16 melanoma, HepG2, and human breast cancer, which had higher levels of activated PKCα, when compared to normal skin, liver, and human breast tissue lysates, respectively. Moreover, addition of Ro‐31‐7549, an inhibitor with great specificity for PKCα, to the phosphorylation reaction caused a dose‐dependent reduction in phosphorylation, but no inhibition was identified with the addition of rottlerin and H‐89. These results show that this peptide has great potential as a PKCα‐specific substrate.
Improvement of photovoltaic performances of organic thin‐film solar cells by fast electron mobility oxadiazole as an exciton blocking layer material
Authors: Ichikawa Musubu , Shimizu Chieko , Koyama Toshiki , Taniguchi Yoshio
Published: April 2008

We demonstrated improvements of photovoltaic performances of organic thin‐film solar cells using an oxadiazole compound (Bpy‐OXD) as an exciton blocking layer (EBL) material. Due to fast electron mobility of Bpy‐OXD of above 10–3 cm2/Vs, the photovoltaic cell with Bpy‐OXD showed higher performance than that with bathocuproine, a conventional EBL material. High amorphous nature of Bpy‐OXD with high glass transition temperature of 106 °C probably also caused a part of the improvements because of protecting photovoltaic layers from damaging during upper metal electrode deposition. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Transparent conductive Ta2O5‐codoped ITO thin films prepared by different heating process
Authors: Zhang B. , Dong X. P. , Xu X. F. , Wu J. S.
Published: April 2008

Tantalum‐doped indium tin oxide thin films were deposited by a cosputtering technique with an ITO target and a Ta2O5 target. The variations of microstructure, electrical and optical properties with substrate temperature and annealing temperature were investigated in some detail. Ta‐doped ITO thin films showed better crystalline structure with different prominent plane orientation by different heating process. ITO:Ta thin films deposited at room temperature showed better optical and electrical properties. Increasing substrate temperature and reasonable annealing temperature could remarkably improve the optical and electrical properties of the films. The variation of carrier concentration had an important influence on near‐IR reflection, near‐UV absorption and optical bandgap. ITO:Ta thin films showed wider optical bandgap. ITO:Ta thin films under the optimum parameters had a sheet resistance of 10–20 Ω/sq and a transmittance of 85% with an optical bandgap of above 4.0 eV. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Off‐diagonal magneto‐impedance in amorphous microwires with diameter 6–10 μm and application to linear magnetic sensors
Authors: Ipatov M. , Zhukova V. , Blanco J. M. , Gonzalez J. , Zhukov A.
Published: April 2008

Off‐diagonal component of magneto‐impedance tensor with pulse excitation is very promising for high sensitivity magnetic field sensor applications. We report novel results on studies of off‐diagonal MI effect and magnetic properties in amorphous glass‐coated microwires with nearly‐zero and negative magnetostriction constant and metallic nucleus diameter ranging between 6 μm and 10 μm. Off‐diagonal impedance tensor ζφz (Hex) has been investigated in ultra‐thin amorphous glass‐coated microwires in as‐cast state and after Joule heating treatment. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Magnetostatic properties of Co‐rich amorphous microwires: theory and experiment
Authors: Aranda G. R. , Usov N. A. , Zhukova V. , Zhukov A. , Gonzalez J.
Published: April 2008

The calculations of the residual quenching stresses and magnetization curves of glass‐coated Co‐rich microwires are carried out to study their dependence on the material parameters characterizing the properties of metallic core and glass shell of the wire. It is shown that Co‐rich microwires with strictly negative magnetostriction must have small remanence and nearly linear dependence of wire magnetization in applied magnetic field. The measured hysteresis loops for a family of Co67Fe3.8Ni1.4Si14.5B11.6Mo1.7 microwires do demonstrate this behaviour. The reasons for the unusual behaviour of some Co‐rich microwires showing finite remanence are discussed in the paper. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Preparation of 3 inch freestanding GaN substrates by hydride vapor phase epitaxy with void‐assisted separation
Authors: Yoshida T. , Oshima Y. , Eri T. , Watanabe K. , Shibata M. , Mishima T.
Published: April 2008

By using the hydride vapor phase epitaxy and a void‐assisted separation method, freestanding 3 inch GaN substrates were successfully fabricated for the first time, and the process showed an excellent reproducibility. A thick GaN layer 3.2 inches in diameter was easily separated from the base substrate. No cracks were generated during the separation process, and the separation process was no more difficult than that of 2 inch GaN substrates. The dislocation density was of the order of 106 cm–2. The carrier density was approximately 1 × 1018 cm–3 and the mobility was 3.4 × 102 cm2 V–1 s–1. The concentrations of impurities, estimated by secondary‐ion mass spectrometry, were below the limit of detection, except for Si. The Si concentration was approximately 1 × 1018 cm–3, which is in good agreement with the carrier density. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High‐efficiency GaN HEMTs on 3‐inch semi‐insulating SiC substrates
Authors: Waltereit P. , Bronner W. , Quay R. , Dammann M. , Müller S. , Kiefer R. , Raynor B. , Mikulla M. , Weimann G.
Published: April 2008

We report on device performance and reliability of our 3″ GaN high electron mobility transistor (HEMT) technology. AlGaN/GaN HEMT structures are grown on semi‐insulating SiC substrates by metal‐organic chemical vapor deposition (MOCVD) with sheet resistance uniformities better than 2%. Device fabrication is performed using standard processing techniques involving both e‐beam and stepper lithography. AlGaN/GaN HEMTs demonstrate excellent high‐voltage stability and large efficiencies. Devices with 0.5 µm gate length exhibit two‐terminal gate‐drain breakdown voltages in excess of 160 V and drain currents well below 1 mA/mm when biased at 80 V drain bias under pinch‐off conditions. Load‐pull measurements at 2 GHz return both a linear relationship between drain bias voltage and output power as well as power added efficiencies beyond 55% up to 72 V drain bias for which an output power density of 9 W/mm with 25 dB linear gain is obtained. Reliability tests indicate a promising device stability under both radio frequency (RF) and direct current (DC) stress conditions. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electro‐optical intersubband modulators at telecommunication wavelengths based on GaN/AlN quantum wells
Authors: Kheirodin N. , Nevou L. , Machhadani H. , Tchernycheva M. , Lupu A. , Julien F. H. , Crozat P. , Meignien L. , Warde E. , Vivien L. , Pozzovivo G. , Golka S. , Strasser G. , Guillot F. , Monroy E. , Remmele T. , Albrecht M.
Published: April 2008

We report the demonstration of intersubband modulators operating at telecommunication wavelengths at room temperature based on GaN/AlN quantum wells. We first investigate electro‐optical modulators making use of electron tunneling in coupled quantum wells. Electro‐absorption modulation with opposite sign induced by the electron tunneling between the reservoir and active quantum wells is observed at λ = 1.3–1.6 µm and λ = 2.2 µm. We show that by reducing the mesa size down to 15 × 15 µm2, optical modulation bandwidth as large as 3 GHz can be obtained. We then investigate waveguide intersubband modulators relying on the depletion of the ground electronic state of a 3 quantum well active region. Modulation depths as large as 14 dB in the wavelength range of 1.2–1.6 µm are obtained under –9 V/+7 V voltage swing. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of growth conditions on the conductivity of Mg doped p‐type GaN by Molecular Beam Epitaxy
Authors: Simon John , Jena Debdeep
Published: April 2008

The performance of III–V nitride heterostructure bipolar transistors has been limited by highly resistive p‐type layers, in addition to difficulties associated with a precise p–n junction placement at the emitter‐base heterojunction due to the Mg‐memory effect during growth by Metal‐Organic Chemical Vapor Deposition. The problem of precise p–n heterojunction placement can be solved by Molecular Beam Epitaxy growth. To investigate this possibility, in this work, we present a comprehensive study of the effect of III/V ratio, growth temperature, and Mg doping on the resistivity of Mg doped GaN layers grown by Molecular Beam Epitaxy. N2‐rich growth conditions are found to lead to a temperature‐ independent low hole mobility, as opposed to Ga‐rich growth conditions that lead to higher hole mobilities that vary with temperature. In addition, the growth temperature, Ga flux, and Mg flux windows leading to the highest p‐type conductivity are identified. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Origin of additional threading dislocations in AlGaN grown on GaN using AlN as an interlayer
Authors: Datta R. , McAleese C. , Cherns P. , Rayment F. D. G. , Humphreys C. J.
Published: April 2008

Thick AlGaN layers with high Al contents (50%) grown epitaxially on GaN crack due to tensile strain arising from the lattice parameter mismatch. AlN can be used to prevent this cracking but there is a concomitant increase in the edge‐type threading dislocations in the AlGaN film. In this contribution the origin of the additional threading dislocations (TDs) is investigated. The AlN interlayer itself micro‐cracks to relieve strain, and overgrowth of AlGaN on such a relaxed/cracked AlN layer gives rise to the generation of additional edge type TDs along the crack lines. This appears to be due to terminated misfit dislocation lines at the crack facets that are replicated during subsequent growth, resulting in additional edge TDs in the upper AlGaN layer. The contribution of cracks in generating additional edge TDs can also depend on whether the crack lines are filled or a void is created during AlGaN growth. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Assessment of the pendeo‐epitaxy effect on 2DEG mobility in III‐nitride HEMT heterostructures
Authors: Bulashevich K. A. , Karpov S. Yu. , Makarov Yu. N. , Zheleva T. S. , Shah P. B. , Derenge M. A. , Jones K. A.
Published: April 2008

We have analyzed theoretically the electron scattering related to the interface roughness produced by threading dislocations in the channel of an AlGaN/GaN HEMT heterostructure. On the basis of the analysis, we predict the use of the pendeo‐epitaxy for growing the transistor structure to improve the low‐temperature and roomtemperature mobility of two‐dimensional electrons by ∼80% and ∼28%, respectively. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fabrication of GaN/AlN bilayer particles by a vapor phase method
Authors: Hara K. , Mori T. , Komoda H. , Oogi Y. , Kominami H. , Nakanishi Y.
Published: April 2008

In contrast to the conventinal powder phosphors consisting of particles with a uniform material composition, GaN‐based nanostructure‐embedded particles, which consist of GaN quantum dots or quantum wells in the AlN matrix, has been proposed. We can expect the novel phosphors to have higher luminescence efficiencies owing to the carrier confinement effect. As a fundamental technique to fabricate such particles, the formation of bilayer particles consisting of an AlN core and a GaN surface layer has been demonstrated by using the two‐stage vapor phase method. The AlN particles were first formed by a reaction of vaporized Al and N2 gas at temperatures from 1100 to 1250 °C in the first reactor, followed by the growth of GaN on the core surface by a reaction of GaCl and NH3 at 1000 °C in the second reactor. Thus fabricated GaN/AlN bilayer particles showed cathodoluminescence dominated by the band edge emission of GaN. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Morphological study of non‐polar (11‐20) GaN grown on r‐plane (1‐102) sapphire
Authors: Johnston C. F. , Kappers M. J. , Barnard J. S. , Humphreys C. J.
Published: April 2008

In order to grow high quality non‐polar GaN‐based LED structures it is important to understand the mechanism of GaN growth by MOVPE on r‐plane (1‐102) sapphire. In this work, (11‐20) GaN epilayers have been characterised at three stages of growth using high resolution X‐ray diffraction (HRXRD), transmission electron microscopy (TEM) and atomic force microscopy (AFM). Following nucleation, 3D islands were grown, then the V/III ratio was lowered and the islands coalesced to form a smooth film. A series of symmetric XRD ω‐scans obtained at different azimuthal angles revealed an anisotropy in the layers with respect to the [1‐100] and [0001] axes. AFM scans show that the islands are elongated along the [0001] axis. TEM has been used to analyse the layers further. A high density of stacking faults (5x105 cm–1) and threading dislocations (4x1010 cm–2) was found in the film with 120 s high V/III growth followed by low V/III growth. Defects were found to run perpendicular and at ∼60 degrees to the sapphire interface in uncoalesced “island” samples. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Assessing the utility of public health surveillance using specificity, sensitivity, and lives saved
Authors: Kleinman Ken P. , Abrams Allyson M.
Published: April 2008

In modern surveillance of public health, data may be reported in a timely fashion and include spatial data on cases in addition to the time of their occurrence. This has lead to many recent developments in statistical methods to detect events of public health importance. However, there has been relatively little work about how to compare such methods. One powerful rationale for performing surveillance is earlier detection of events of public health significance; previous evaluation tools have focused on metrics that include the timeliness of detection in addition to sensitivity and specificity. However, such metrics have not accounted for the number of persons affected by the events. We re‐examine the rationale for this surveillance and conclude that earlier detection is preferred because it can prevent additional morbidity and mortality. On the basis this observation, we propose evaluating the number of cases prevented by each detection method, and include this information in assessing the value of different detection methods. Using this approach incorporates more information about the events and the detection and provides a sound basis for making decisions about which detection methods to employ. Copyright © 2008 John Wiley & Sons, Ltd.
Participation of Rho, ROCK‐2, and GAP activities during actin microfilament rearrangements in Entamoeba histolytica induced by fibronectin signaling
Authors: Ríos Amelia , Hernández‐Ramírez Verónica Ivonne , Moguel Mayra , Zárate Bahena Alma Iris , Rosales‐Encina José Luis , Vargas Miguel Angel , Talamás‐Rohana Patricia
Published: April 2008

In Entamoeba histolytica little is known about the microfilament rearrangements formed by actin and ABPs. Fibronectin regulates many aspects of cell behavior involving the actin cytoskeleton and members of the Rho family of small GTPases. Using trophozoites interacted with fibronectin and glass, we present evidence related with the formation and regulation of different microfilament rearrangements and their cellular distribution, the effect of actin affecting drugs on these arrangements, and on trophozoites adhesion; we also demonstrate that actin isoforms are induced after adhesion, and also the selective participation of specific actin binding proteins such as ABP‐120 and phospho‐paxillin, regarding their location in the different actin structures. In addition, we show results that confirm the participation of EhRho, ROCK‐2, and GAP activities. We propose that fibronectin induced signaling in E. histolytica trophozoites have important consequences in the actin cytoskeleton that may affect its behavior during the invasive process in the host.
Authors: Mukherjee Janam
Published: April 2008

Anthropologist Veena Das here revisits two critical events in Indian history: the Partition riots of 1947, and the violence against Sikhs following the 1984 assassination of Prime Minister Indira Gandhi. Though Das has grappled with complex (and sometimes tortured) analyses of these same events in previous works, Life and Words represents an important departure from her more narrowly ethnographic essays. She readjusts her focus toward a theoretical/philosophical interrogation of the “ordinary” in an effort to complicate existing temporal and epistemological assumptions that have characterized studies of violence in India. The book is a two-part study: It first examines the way in which extraordinary violence (in this case that of Partition) gets “folded” into the everyday lives of those who have survived catastrophe. Second, she turns to how the violence of everyday life provides the necessary conditions for “eventful” eruptions of collective violence (in this case that against Sikhs in 1984). In blurring the boundaries between the ordinary and the eventful, Das is able to gain significant insights into the interface between the individual and the collective, the local and the supralocal, and the historical and the anthropological.
Theory and simulations of whistler wave propagation
Authors: SHAIKH DASTGEER
Published: April 2008

A linear theory of whistler waves is developed within the paradigm of a two-dimensional incompressible electron magnetohydrodynamics model. Exact analytic wave solutions are obtained for small-amplitude whistler waves that exhibit magnetic field topological structures consistent with the observations and our simulations in a linear regime. In agreement with experiment, we find that the parallel group velocity of the wave is large compared to its perpendicular counterpart. Numerical simulations of collisional interactions demonstrate that the wave magnetic field either coalesces or repels depending upon the polarity of the associated current. In the nonlinear regime, our simulations demonstrate that the evolution of the wave magnetic field is governed essentially by the nonlinear Hall force.
Use of host population reduction to control wildlife infection: rabbits and paratuberculosis
Authors: DAVIDSON R. S. , MARION G. , WHITE P. C. L. , HUTCHINGS M. R.
Published: April 2008

Reduction in wildlife populations is a common method for the control of livestock infections which have wildlife hosts, but its success is dependent on the characteristics of the infection itself, as well as on the spatial and social structure of the wildlife host. Paratuberculosis (Mycobacterium avium subsp. paratuberculosis; Map) is a widespread and difficult infection to control in livestock populations and also has possible links to Crohn's disease in humans. Rabbits have recently been identified as a key wildlife species in terms of paratuberculosis persistence in the environment and risk to the wider host community, including cattle. Here we use a spatially explicit stochastic simulation model of Map dynamics in rabbit populations to quantify the effects of rabbit population control on infection persistence. The model parameters were estimated from empirical studies of rabbit population dynamics and rabbit-to-rabbit routes of Map transmission. Three rabbit control strategies were compared: single unrepeated population reductions based on removing individual animals; single unrepeated population reductions based on removal of entire social groups; and repeated annual population reductions based on removing individual animals. Unrealistically high rabbit culls (>95% population reduction) are needed if infection is to be eradicated from local rabbit populations with a single one-off population reduction event, either of individuals or social groups. Repeated annual culls are more effective at reducing the prevalence of infection in rabbit populations and eradicating infection. However, annual population reductions of >40% are required over extended periods of time (many years). Thus, using an approach which is both highly conservative and parsimonious with respect to estimating lower bounds on the time to eradicate the infection, we find that Map is extremely persistent in rabbit populations and requires significant and prolonged effort to achieve control.
Multiclonal outbreak of methicillin-resistant Staphylococcus aureus infections on a collegiate football team
Authors: HALL A. J. , BIXLER D. , HADDY L. E.
Published: April 2008

An outbreak of methicillin-resistant Staphylococcus aureus (MRSA) skin and soft tissue infections (SSTIs) occurred in a college football team in August 2006. Of 109 players on the team roster, 88 (81%) were interviewed during a cohort investigation. Twenty-five cases were identified, six of which were culture-confirmed. Available culture isolates were typed by pulsed-field gel electrophoresis (PFGE), which identified two different MRSA strains associated with the outbreak. Playing positions with the most physical contact (offensive linemen, defensive linemen, and tight ends) had the greatest risk of infection [risk ratio (RR) 5·1, 95% confidence interval (CI) 2·3–11·5. Other risk factors included recent skin trauma (RR 1·9, 95% CI 0·95–3·7), use of therapeutic hydrocollator packs (RR 2·5, 95% CI 1·1–5·7), and miscellaneous training equipment use (RR 2·1, 95% CI 1·1–4·1). The outbreak was successfully controlled through team education and implementation of improved infection-control practices and hygiene policies.
Comment: US – Countervailing Duty Investigation of DRAMS
Authors: PRUSA THOMAS J.
Published: April 2008

There are two compelling issues involved in US – Countervailing Duty Investigation of DRAMS. First, there is the question of whether creditors were ‘entrusted or directed’ to make financial contributions to Hynix, a large South Korean DRAM producer. This was the main topic addressed by the Appellate Body (AB) and is the focus of the François–Palmeter paper. Second, there is there is the question of injury assessment and nonattribution. Because the US did not appeal the Panel's decision, this aspect of the WTO dispute was not considered by the AB.
Towards probabilistic projections of climate change impacts on global crop yields
Authors: Tebaldi C. , Lobell D. B.
Published: April 2008

There is a widely recognized need in the scientific and policy communities for probabilistic estimates of climate change impacts, beyond simple scenario analysis. Here we propose a methodology to evaluate one major climate change impact ‐ changes in global average yields of wheat, maize, and barley by 2030 ‐ by a probabilistic approach that integrates uncertainties in climate change and crop yield responses to temperature, precipitation, and carbon dioxide. The resulting probability distributions, which are conditional on assuming the SRES A1B emission scenario and no agricultural adaptation, indicate expected changes of +1.6%, −14.1%, −1.8% for wheat, maize, and barley, with 95% probability intervals of (−4.1, +6.7), (−28.0, −4.3), (−11.0, 6.2) in percent of current yields, respectively. This fully probabilistic analysis aims at quantifying the range of plausible outcomes and allows us to gauge the relative importance of different sources of uncertainty.
High Serum Leptin Is Associated with Attenuated Coronary Vasoreactivity
Authors: Sundell Jan , Huupponen Risto , Raitakari Olli T. , Nuutila Pirjo , Knuuti Juhani
Published: April 2008

Objective: Hyperleptinemia, a hallmark of obesity, appears to be a risk factor for coronary artery disease. However, although leptin is a vasoactive hormone, no studies addressing leptin's effect on coronary perfusion have been performed. We examined the association between circulating leptin concentration and coronary vasoreactivity in young obese and nonobese males.

Research Methods and Procedures: Myocardial blood flow was quantitated in 10 obese men (age 31 ± 7 years, BMI 34 ± 2 kg/m2) and 10 healthy matched nonobese men (age 33 ± 8 years, BMI 24 ± 2 kg/m2) using positron emission tomography and O‐15‐water. The measurements were performed basally and during adenosine infusion (140 μg/kg per minute).

Results: Serum leptin was significantly higher in obese than nonobese subjects (10.3 ± 5.6 vs. 4.3 ± 2.5 ng/mL, p < 0.01). Basal myocardial blood flow was not significantly different between obese and nonobese subjects. Adenosine‐stimulated flow was blunted in obese (3.2 ± 0.6 mL/g per minute) when compared with nonobese subjects (4.0 ± 1.1 mL/g per minute, p < 0.05). Serum leptin concentration was inversely associated with adenosine‐stimulated flow in study subjects (r = −0.50, p < 0.05). This association was no longer observed after adjustment for obesity and/or hyperinsulinemia.

Discussion: Hyperleptinemia and reduced coronary vasoreactivity occur concomitantly in young obese but otherwise healthy men. Moreover, the adenosine‐stimulated myocardial flow is inversely related to prevailing concentration of serum leptin. Although this relationship appears to be explained by obesity and/or hyperinsulinemia, leptin might have a role in regulation of myocardial blood supply.