bluuebunny/crossref_metadata_2025 huggingface dataset:
Estimating prevalence of serious emotional disturbance in schools using a brief screening scale
Authors: Li Fan , Green Jennifer Greif , Kessler Ronald C. , Zaslavsky Alan M.
Published: May 2010

Information about the prevalence of serious mental illness (SMI) among adults or serious emotional disturbance (SED) among youth in small domains such as counties, states, or schools is valuable for mental health policy planning purposes, but prohibitively expensive to collect with semi‐structured surveys. Commonly used synthetic estimation methods yield imprecise estimates. An improved method is described here that combines information about socio‐demographic covariates with screening scale scores obtained from a sample of individuals, using a prediction equation derived from a Bayesian multilevel regression model with bivariate outcomes fitted to a larger population survey. This method is illustrated using K6 screening scale scores to predict school‐level prevalence of SED in the sample of 282 schools that participated in the National Comorbidity Survey Replication Adolescent Supplement. Respondents completed a diagnostic interview that was used to define DSM‐IV SED. SED prevalence varied significantly across schools and was strongly correlated with aggregate K6 scores (ρ = 0.70). Calculations suggest that near‐maximum precision of school‐level SED prevalence estimates could be attained with K6 samples of 200 students per school. This modeling approach holds great promise for generating accurate estimates of SMI/SED in small‐area planning units based on K6 scores collected in ongoing health tracking surveys. Copyright © 2010 John Wiley & Sons, Ltd.
Screening for serious mental illness: methodological studies of the K6 screening scale
Authors: Wittchen Hans‐Ulrich
Published: May 2010

The K6 scale is a shortened version of the K10, a 10‐question scale originally developed to provide an efficient population‐level screen for serious mental disorders (SMI) in the USA. Evidence that the six‐item shortened version performed as well as the original 10‐item version, coupled with strong psychometric properties, led to rapid dissemination and replicated validation of the K6 in a number of other countries around the world. Based on these results, the K6 is now often included in large general‐purpose government health tracking surveys in a number of different countries. Until now, though, the scoring rules for the K6 in these surveys were inconsistent. The first paper in this special issue introduces the K6 scale and summarizes the results of a series of investigations to resolve these inconsistencies by providing optimal scoring rules for the K6 in 14 countries. Subsequent papers explore the usefulness of the K6 to screen for serious emotional disturbance among adolescents and report findings from validation efforts based on independent diagnostic assessments as well as of other measures of impairment and disability (World Health organization Disability Assessment Scale). Finally a highly innovative analysis using a Bayesian multilevel modeling approach is presented, designed to estimate the prevalence of SMI in small areas, such as cities, states, or schools, from surveys carried out in a larger population that includes only relatively small samples of respondents in each of the areas in which prevalence estimates are to be made. Taken together, these studies demonstrate that the K6 is an efficient and useful screening tool. The psychometric and methodological explorations will hopefully stimulate additional interest in the use of short screening scales in large‐scale general health surveys to supplement the more in‐depth information obtained in periodic psychiatric epidemiological surveys on the basis of diagnostic interviews. Copyright © 2010 John Wiley & Sons, Ltd.
Steady‐state diffusion‐weighted imaging: theory, acquisition and analysis
Authors: McNab Jennifer A. , Miller Karla L.
Published: May 2010

Steady‐state diffusion‐weighted imaging (DWI) has long been recognized to offer potential benefits over conventional spin‐echo methods. This family of pulse sequences is highly efficient and compatible with three‐dimensional acquisitions, which could enable high‐resolution, low‐distortion images. However, the same properties that lead to its efficiency make steady‐state imaging highly susceptible to motion and create a complicated signal with dependence on T1, T2and flip angle. Recent developments in gradient hardware, motion‐mitigation techniques and signal analysis offer potential solutions to these problems, reviving interest in steady‐state DWI. This review offers a description of steady‐state DWI signal formation and provides an overview of the current methods for steady‐state DWI acquisition and analysis. Copyright © 2010 John Wiley & Sons, Ltd.
Measuring the acute effect of insulin infusion on ATP turnover rate in human skeletal muscle using phosphorus‐31 magnetic resonance saturation transfer spectroscopy
Authors: Lim Ee Lin , Hollingsworth Kieren G. , Thelwall Peter E. , Taylor Roy
Published: May 2010

Mitochondrial dysfunction has been proposed to underlie the insulin resistance of type 2 diabetes. However, the relative time course of insulin action in stimulating ATP turnover rate and glucose uptake in skeletal muscle has not been examined. These two parameters were measured in young healthy subjects using the 31P MRS saturation transfer method in conjunction with the euglycaemic hyperinsulinaemic clamp technique respectively. Glucose infusion rate rose rapidly from 0 to 2.90 ± 0.11 mg/kgffm/min during the first 10 min of insulin infusion and further to 6.17 ± 0.57 mg/kgffm/min between 15 and 45 min. In contrast, baseline ATP turnover rate was 9.0 ± 0.4 µmol/g/min of muscle and did not change during the first 45 min of insulin infusion. Between 50 and 80 minutes ATP turnover rate increased by 8% and remained steady to 150 minutes (9.7 ± 0.5 µmol/g/min of muscle, p = 0.03 vs baseline). The in vivo time course of insulin stimulation of skeletal muscle ATP turnover rate is not consistent with a rate limiting effect upon the initiation of insulin‐stimulated glycogen synthesis. Copyright © 2010 John Wiley & Sons, Ltd.
Fast T2 relaxometry with an accelerated multi‐echo spin‐echo sequence
Authors: Sénégas Julien , Liu Wei , Dahnke Hannes , Song Hotaek , Jordan E. Kay , Frank Joseph A.
Published: May 2010

A new method has been developed to reduce the number of phase‐encoding steps in a multi‐echo spin‐echo imaging sequence allowing fast T2 mapping without loss of spatial resolution. In the proposed approach, the k‐space data at each echo time were undersampled and a reconstruction algorithm that exploited the temporal correlation of the MR signal in k‐space was used to reconstruct alias‐free images. A specific application of this algorithm with multiple‐receiver acquisition, offering an alternative to existing parallel imaging methods, has also been introduced. The fast T2 mapping method has been validated in human brain T2 measurements in a group of nine volunteers with acceleration factors up to 3.4. The results demonstrated that the proposed method exhibited excellent linear correlation with the regular T2 mapping with full sampling and achieved better image reconstruction and T2 mapping with respect to SNR and reconstruction artifacts than the selected reference acceleration techniques. The new method has also been applied for quantitative tracking of injected magnetically labeled breast cancer cells in the rat brain with acceleration factors of 1.8 and 3.0. The proposed technique can provide an effective approach for accelerated T2 quantification, especially for experiments with single‐channel coil when parallel imaging is not applicable. Copyright © 2010 John Wiley & Sons, Ltd.
Statin and NSAID use and prostate cancer risk
Authors: Coogan Patricia F. , Kelly Judith Parsells , Strom Brian L. , Rosenberg Lynn
Published: May 2010

Purpose

Some studies have reported reduced risks of advanced, but not early, prostate cancer among statin users, and one study found a reduced risk only among statin users who had also used non‐steroidal anti‐inflammatory drugs (NSAIDs). We have previously reported no association between statin use and prostate cancer in our hospital‐based Case Control Surveillance Study. The purpose of the present analyses was to update the findings by cancer stage and to evaluate the joint use of statins and NSAIDs.

Methods

Cases were 1367 men with prostate cancer and controls were 2007 men with diagnoses unrelated to statin or NSAID use. We used multivariable logistic regression analyses to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for statin use compared with no use, and joint use of statin and NSAIDs compared with use of neither.

Results

The odds ratio among regular statin users was 1.1 (95%CI 0.9–1.5), and odds ratios were similar among early and late stage cancers. The odds ratio among joint statin and NSAID users was 1.1 (95%CI 0.7–1.6).

Conclusion

The present results do not support a protective effect of statin use, or statin and NSAID use, on the risk of advanced prostate cancer. Copyright © 2010 John Wiley & Sons, Ltd.
The 6th HUPO Antibody Initiative (HAI) Workshop: Sharing Data About Affinity Reagents and Other Recent Developments September 2009, Toronto, Canada
Authors: Jonasson Kalle , Berglund Lisa , Uhlen Mathias
Published: May 2010

The Human Antibody Initiative (HAI) aims to promote and facilitate the use of antibodies for proteomics research. The 6th workshop for the HUPO Antibody Initiative (HAI) held in September 2009 was co‐chaired by Michael Snyder and Mathias Uhlen and discussed several aspects of antibody production, their validation, and attempts to standardise this process, in particular, when subsequently described in the literature. An update on the progress of the Human Protein Atlas was also presented to the attendees.
Growth and electron microscopy study of GaN/MgAl2O4 heterostructures
Authors: Li Guoqiang , Shih Shao‐Ju , Fu Li
Published: May 2010

We successfully grew Gallium nitride (GaN) films on MgAl2O4 (111) substrates using low temperature pulsed laser deposition (PLD). X‐ray diffraction rocking curves revealed the high quality of as‐grown GaN with its full width at half maximum (FWHM) along [0002] as small as 0.08°. Atomic force microscopy images showed very smooth surface of as‐grown GaN and indicated a two‐dimensional growth. High‐resolution transmission electron microscopy showed high structural perfection of GaN films. The crystalline structure for MgAl2O4 substrate from its body to its top part adjacent to GaN epitaxy kept constant, and the interface between GaN and MgAl2O4 was atomically abrupt. We attribute the high quality of as‐grown GaN films to the well‐controlled Mg atom evaporation from MgAl2O4 substrate surface owing to the application of low growth temperature in PLD: on the one hand, it avoids the severe interfacial reaction that is very likely to take place in conventional MOCVD or MBE growth, and hence makes the epitaxial growth possible; on the other hand, it conserves the crystalline structure of the substrate surface, and consequently takes good advantage of the small lattice mismatch between GaN and MgAl2O4.
Transparent and conductive undoped zinc oxide thin films grown by atomic layer deposition
Authors: Luka Grzegorz , Krajewski Tomasz , Wachnicki Lukasz , Witkowski Bartlomiej , Lusakowska Elzbieta , Paszkowicz Wojciech , Guziewicz Elzbieta , Godlewski Marek
Published: May 2010

Atomic layer deposition (ALD) was used to fabricate transparent and conductive thin films of ZnO. Two hundred‐nano metre thick ZnO films were deposited on glass substrates at low growth temperatures varied between 120 and 240 °C. As zinc and oxygen precursors we used diethylzinc (DEZn) and deionized water, respectively. To find optimal film parameters, the structure, surface morphology, optical and electrical measurements were carried on. The films obtained at 200 °C show the highest carrier concentration (∼1020 cm−3) and the lowest resistivity (2 × 10−3 Ω cm). The films exhibit mobilities up to 37 cm2/Vs that we associate to the process technology used. An important point of our approach was that the films studied were not intentionally doped (with Al or other group III elements) but the high electrical conductivity was achieved by playing with the sample stoichiometry and growth conditions.
Annealing effect on the structural, opto‐electronic and photoluminescence properties of sprayed Zn0.76Mg0.24O films for application in solar cells
Authors: Prathap P. , Suryanarayana Reddy A. , Revathi N. , Venkata Subbaiah Y. P. , Ramakrishna Reddy K. T.
Published: May 2010

In recent years, Zn1−xMgxO has attracted the attention of many researchers as its physical behaviour can be suitably controlled by varying the Zn/Mg ratio. The superior advantages associated with Zn1−xMgxO make this material as a potential candidate for application in Cu(InGa)Se2‐based solar cells. In the present investigation, Zn1−xMgxO films have been prepared by spray pyrolysis at 300 °C and subsequently annealed in argon and oxygen ambience at temperatures that vary in the range, 100–500 °C. The changes occurred in the physical characteristics of the layers as a function of annealing temperature have been studied. The influence of annealing on the structure, topography, opto‐electronic and photoluminescence properties was found to be significant. The results have been presented and discussed.
Performance of top‐gate thin film transistors with solution processed ZnO channel layer and PVP gate dielectric
Authors: Nayak Pradipta K. , Kim Jinwoo , Lee Changhee , Hong Yongtaek
Published: May 2010

The performance of top‐gate thin film transistors with solution processed zinc oxide (ZnO) channel layer and poly(4‐vinylphenol) (PVP) gate dielectric have been investigated. The transparency of the PVP film was more than 80% in the visible region, indicating that PVP can be used as a potential dielectric layer for transparent electronics. The TFTs with as‐prepared ZnO as the channel layer showed a saturation field effect mobility of 6.4 × 10−3 cm2/Vs with an on/off ratio of 30. The performances of the TFTs were enhanced after oxygen annealing of the ZnO channel layer prior to PVP deposition. The TFTs with 1 h oxygen annealed ZnO as the channel layer showed a saturation mobility of 0.05 cm2/Vs with an on/off ratio of 2.1 × 102. The obtained results are encouraging for fabrication of all solution processed ZnO based TFTs for cost effective technological applications.
Application of ZnO and poly‐Si in thin‐film heterostructures
Authors: Angelov Orlin , Nichev Hristo , Sendova‐Vassileva Marushka , Dimova‐Malinovska Doriana
Published: May 2010

In this work, thin‐film heterojunction is prepared using ZnO and poly‐Si thin films and its I–V characteristics are presented. ZnO thin films have been applied for device engineering in different heterostructures, as well. In this work, the I–V characteristics of a thin‐film heterostructure n‐ZnO/poly‐Si are studied. The ZnO polycrystalline films are deposited by RF sputtering in an atmosphere of Ar on the surface of a p‐type poly‐Si layer. The poly‐Si films are prepared on glass substrate by the method of aluminum‐induced crystallization (AIC) from precursor layers of Al and a‐Si:H. The Al and a‐Si:H precursor films are deposited by magnetron sputtering on glass substrate. The a‐Si:H film precursors contain 9 at% hydrogen. The isothermal annealing of the structure glass/Al/a‐Si:H is performed in forming gas (N2 + 5%H2) in the temperature range of 530–550 °C for 7 and 21 h. The properties of the films are studied by X‐ray diffraction (XRD), optical microscopy, optical transmission and reflection, and Raman spectroscopy. The I–V characteristics of the thin‐films heterostructure n‐ZnO/ poly‐Si show diode behavior and ideality factor of 2.95.The structure exhibits photosensitivity under illumination.
Detection of volatile organic compounds using a polythiophene derivative
Authors: Gonçalves V. C. , Nunes B. M. , Balogh D. T. , Olivati C. A.
Published: May 2010

Conjugated polymers have been subject of great interest in the recent literature from both fundamental point of view and applied science perspective. Among the several types of conjugated polymers used in recent investigations, polythiophene and its derivatives have attracted considerable attention over the past 20 years due to their high mobility and other remarkable solid‐state properties. They have potential applications in many fields, such as microelectronic devices, catalysts, organic field‐effect transistors, chemical sensors, and biosensors. They have been studied as gas and volatile organic compounds (VOCs) sensors using different principles or transduction techniques, such as optical absorption, conductivity, and capacitance measurements. In this work, we report on the fabrication of gas sensors based on a conducting polymer on an interdigitated gold electrode. We use as active layer of the sensor a polythiophene derivative: poly (3‐hexylthiophene) (P3HT) and analyzed its conductivity as response for exposure to dynamic flow of saturated vapors of six VOCs [n‐hexane, toluene, chloroform, dichloromethane, methanol, and tetrahydrofuran (THF)]. Different responses were obtained upon exposure to all VOCs, THF gave the higher response while methanol the lower response. The influence of moisture on the measurements was also evaluated.
Electrical characteristics of solution‐processed InGaZnO thin film transistors depending on Ga concentration
Authors: Kim Gun Hee , Jeong Woong Hee , Kim Hyun Jae
Published: May 2010

We investigated the role of Ga in solution‐processed InGaZnO thin film transistors (TFTs). The incorporation of Ga into a InZnO compound system results in a decrease in the carrier concentration of the films and an off‐current of TFTs. This is a result of the Ga ions forming stronger chemical bonds with oxygen, as compared to the Zn and In ions, acting as a carrier suppressor. It was verified, using X‐ray photoelectron spectroscopy (XPS), that the vacancy‐related oxygen 1s peak was decreased when the Ga content increased.
Effect of nitrogen doping on photoresponsivity of ZnO films
Authors: Ievtushenko A. I. , Lashkarev G. V. , Lazorenko V. I. , Karpyna V. A. , Dusheyko M. G. , Tkach V. M. , Kosyachenko L. A. , Sklyarchuk V. M. , Sklyarchuk O. F. , Avramenko K. A. , Strelchuk V. V. , Horvath Zs. J.
Published: May 2010

Investigations of photoelectrical properties of ZnO films are important scientific task for designing UV detectors for various applications. We report the positive role of nitrogen doping in increasing photoresponsivity of ZnO:N‐based detectors. It is suggested that nitrogen slightly deteriorates the structural quality of ZnO films and compensates intrinsic defects that increase photoresponsivity. Also, the spectral response of Ni/ZnO:N/n+‐Si structures at different biases were considered.

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Atomic and electronic structures at ZnO and ZrO2 interface for transparent thin‐film transistors
Authors: Wang S. J. , Wong T. I. , Chen Q. , Yang M. , Wong L. M. , Chai J. W. , Zhang Z. , Pan J. S. , Feng Y. P.
Published: May 2010

In this paper, we report the studies of atomic and electronic structures at ZnO and ZrO2 interface. The epitaxial heterostructures were grown by laser molecular beam epitaxy and the interface atomic structure was determined by using high‐resolution transmission electron microscopy (TEM). Band alignment for high‐k ZrO2 layer on ZnO was investigated by in situ X‐ray photoemission spectroscopy (XPS) characterization and first‐principles calculations based on density functional theory (DFT). The valence and conduction band offsets (CBOs) were found to be 0.27 ± 0.05 eV and 2.16 ± 0.05 eV, respectively. The results are in good agreement with values from theoretical calculations. The large CBO and small lattice mismatch between ZnO and ZrO2 suggest potential for ZrO2 to be used as a gate dielectric in ZnO‐based transparent electronic devices.
Controllable crystallinity of synthesized In–Ga–Zn–O nano‐powder by using a pulp precursor for printing processes
Authors: Jung Chulho , Choi Min Suk , Choi Kwang Ho , Yoon Dae Ho
Published: May 2010

IGZO nanoparticles were synthesized using a pulp processor at different temperatures and solution concentrations for the printing processes. The nanoparticles were characterized by field emission scanning electron microscopy (FESEM), powder X‐ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). The nanoparticles synthesized in a 10% of solution were 10–20 nm in diameter. On the other hand, the nanoparticles synthesized in 1 and 0.1% solution were ∼10 nm in diameter, as revealed by HRTEM. From the powder XRD and HRTEM results, the crystallinity of the IGZO nanoparticles decreased with decreasing solution concentration. In particular, the crystallinity was affected significantly by the indium concentration.
Synthesis of light‐coloured nanoparticles of wide band gap p‐type semiconductors CuGaO2 and LaOCuS by low temperature hydro/solvothermal processes
Authors: Chavillon B. , Cario L. , Doussier‐Brochard C. , Srinivasan R. , Le Pleux L. , Pellegrin Y. , Blart E. , Odobel F. , Jobic S.
Published: May 2010

We report here two original low temperature routes for the synthesis of nanostructured particles of p‐type TCO's CuGaO2 and LaOCuS. Light grey CuGaO2 nanolayered particles (∼300 nm large and 5 nm thick) were prepared from a hydrothermal synthetic route using soluble hydrated metal nitrates as precursors and ethylene glycol (EG) as reducing agent. We found then that the initial pH of the precursor's solution is a key parameter to tune the particle sizes (from 2 µm to 300 nm) and subsequently the colour (from dark brown to light grey) of the CuGaO2 powder. LaOCuS was obtained for the first time as greyish nanolayered particles (∼100 nm large and 10 nm thick) via a solvothermal route in ethylene diamine with hydrate chloride lanthanum, copper mono oxide and elemental sulphur as precursors. We found that the control of the chloride lanthanum precursor hydration rate is of prime importance to achieve pure material and to tune the colour of the LaOCuS sample. Both CuGaO2 and LaOCuS nanolayered particles synthesized via these soft chemistry routes exhibit all the characteristics of transparent p‐type semiconductors

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Optical properties of organic thin films deposited via organic vapour phase deposition
Authors: Laskarakis Argiris , Georgiou Despoina , Logothetidis Stergios
Published: May 2010

In recent years, organic semiconductors attracted a lot of attention due to their potential use in organic electronics such as light emitting diodes (OLEDs), photovoltaics and photodetectors. Tris‐(8‐hydroxyquinoline)‐aluminium(III) (Alq3) and N,N_‐di‐[(1‐naphthyl)‐N,N‐diphenyl]‐(1,1‐biphenyl)‐4,4‐diamine (α‐NPD) are among the most commonly used electron transport and hole‐transport materials in OLEDs, respectively. In this work, Alq3 and α‐NPD thin films with various thickness values were deposited onto Si and glass substrates by organic vapour phase deposition (OVPD). Spectroscopic Ellipsometry (SE) in a wide spectral region from the infrared (IR) (900–4000 cm−1) to the near infrared–visible–far ultraviolet (NIR–Vis–fUV, 0.7–6.5 eV) has been implemented in order to investigate the influence of the thickness on their optical and structural properties. From the analysis of the SE spectra, we estimated the band gap values, the optical absorptions and the vibrational response of the materials. The results showed that the α‐NPD thin films show four characteristic absorptions and the optical response of the material is independent of the films thickness. Finally, in case of Alq3, the material shows a band gap at 2.7 eV and three characteristic absorptions.
Influence of stabilizers in ZnO nano‐dispersions on the performance of solution‐processed FETs
Authors: Mechau Norman , Bubel Simon , Nikolova Donna , Hahn Horst
Published: May 2010

Solution‐processed field‐effect transistors (FETs) based on inorganic nano‐materials are attractive system for applications in the field of printable electronics. Stabilized suspensions made of zinc oxide nano‐particles were used to fabricate FETs by spin coating. The performance of such devices is strongly affected by the nature and concentration of the compounds added to stabilize the nano‐dispersions. In this work we compare the field‐effect mobility of zinc oxide transistors when the nano‐particle dispersion is prepared using two different types of commercially available stabilizers. For the stabilizer TEGO Dispers 752 W we observed an increase in the field‐effect mobility by more than one order of magnitude. In contrast, for TEGO Dispers 750 W where a decrease in the field‐effect mobility of more than two orders of magnitude was observed. This stark difference is attributed to be due to the electrical conductivity of the stabilizers, the morphology and interface roughness and the stabilizer particle interaction.
Study on the durability against heat in ITO/Ag‐alloy/ITO transparent conductive multilayer system
Authors: Roh Hee‐Sook , Cho Sun‐Hee , Lee Won‐Jong
Published: May 2010

We studied the effects of added metallic elements in Ag‐alloy layers of indium‐tin‐oxide (ITO)/Ag‐alloy/ITO transparent conductive multilayer system on the durability against heat. When Ag film was heat treated, agglomeration occurred due to the surface diffusion of the Ag atoms. This caused an increase in the sheet resistance and a decrease in the transmittance. Added metallic elements such as Au, Pd, and Cu in Ag‐alloy layers increased the onset temperature and activation energy for agglomeration. These added metallic elements also decreased the surface energy of the Ag film. The durability against heat was improved by adding metallic elements to the Ag film of the ITO/Ag/ITO multilayer system. Cu atoms, especially, diffused out to the surface of the Ag film hindered the surface diffusion of the Ag atoms, resulting the improvement of thermal stability of the Ag film. The figure of merit (FOM, T10/R□) of ITO/Ag/ITO multilayer decreased to 1/15 of its initial value after heat treatment at 450 °C for 6 h, whereas it decreased to 1/3 of its initial value when Pd and Cu were added to Ag film.
Subgap states, doping and defect formation energies in amorphous oxide semiconductor a‐InGaZnO4 studied by density functional theory
Authors: Kamiya Toshio , Nomura Kenji , Hosono Hideo
Published: May 2010

Amorphous In‐Ga‐Zn‐O (a‐IGZO) is expected for channel layers in thin‐film transistors (TFTs). It is known that a‐IGZO is sensitive to an O/H‐containing atmosphere; therefore, it is important to clarify the roles of oxygen and hydrogen in a‐IGZO. This paper provides atomic and electronic structures, formation energies of defects and bond energies in a‐IGZO calculated by first‐principles density functional theory (DFT). It was confirmed that oxygen deficiencies having small formation energies (2–3.6 eV) form either deep fully‐occupied localized states near the valence band maximum or donor states, which depend on their local structures. All the hydrogen doping form OH bond and work as a donor. The stable OH bonds have small formation energy of ∼0.45 eV and consist of three metal cations coordinated to the O ion. The bond energy of GaO is calculated to be ∼2.0 eV, which is the largest among the chemical bonds in a‐IGZO (1.7 eV for InO and 1.5 eV for ZnO). This result supports the idea that the incorporation of Ga stabilizes a‐IGZO TFTs.
Epitaxial growth of ZnO thin films on AlN substrates deposited at low temperature by magnetron sputtering
Authors: Rahmane S. , Abdallah B. , Soussou A. , Gautron E. , Jouan P.‐Y. , Le Brizoual L. , Barreau N. , Soltani A. , Djouadi M. A.
Published: May 2010

Hexagonal aluminium nitride (AlN) and zinc oxide (ZnO) thin films have been deposited by DC and RF reactive magnetron sputtering at room temperature. For a first set of samples, sputtered AlN films were deposited on silicon ZnO substrate. For a second set, ZnO films were deposited on AlN substrate. X‐ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM) analysis of the synthesized AlN film on ZnO buffer layer have shown some amorphous zones close to the interface followed by a nanocrystalline layer exhibiting (10−10) and (0002) orientations of the hexagonal AlN crystalline phase. At the top of the film, a relatively well‐crystallized layer with a single (0002) orientation has been observed. We have related the relatively bad interface to the presence of oxygen coming from ZnO substrate. This behaviour was different for the growth of ZnO film when AlN was used as substrate. In fact, we have observed thanks to HRTEM images and selected area electron diffraction patterns, that the ZnO film deposited on AlN substrate exhibits an epitaxial growth which is strongly dependent on the crystalline quality of AlN film.
Mg‐related acceptors in GaN
Authors: Monemar B. , Paskov P. P. , Pozina G. , Hemmingsson C. , Bergman J. P. , Amano H. , Akasaki I. , Figge S. , Hommel D. , Paskova T. , Usui A.
Published: May 2010

Photoluminescence spectra of c ‐plane Mg doped GaN samples grown by MOVPE on bulk GaN templates reveal previously unknown properties, like the presence of several Mg‐related acceptors. The use of unstrained samples allows a study of both bound exciton (BE) and donor‐acceptor pair (DAP) spectra. Two main acceptors A1 and A2 are observed strongly in BE spectra as well as in DAP spectra, they have similar binding energies, i.e. about 220 meV. The common assignment of the deeper blue PL emission at 2.8–3.0 eV to a deep donor‐shallow acceptor transition is questioned, and discussed in connection with the compensation problem in p‐GaN. It seems like the Fermi level in p‐GaN is controlled by a set of Mg‐related acceptors at energies 0.2–0.6 eV from the valence band top. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Photoluminescence of GaN/AlN quantum dots at high excitation powers
Authors: Aleksandrov Ivan , Zhuravlev Konstantin
Published: May 2010

Excitation power and temperature dependencies of the photoluminescence (PL) of wurtzite GaN/AlN quantum dots (QDs) grown by molecular beam epitaxy have been investigated. The PL band of the QDs exhibited a shift to lower energy with increasing excitation power. This red shift was attributed to the band‐gap renormalization. The non‐stationary PL decay law is non‐exponential and varies over the spectrum. The PL band of the GaN/AlN QDs shifts to lower energy with delay time after a pulsed excitation as a result of the increase of the carrier lifetime with increase in the QD size. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High‐temperature operation of GaN‐based OPAMP on silicon substrate
Authors: Nomoto Kazuki , Hasegawa Kazuya , Nakamura Tohru
Published: May 2010

We demonstrated electrical characteristics of operational amplifier (OPAMP) circuits fabricated by GaN/AlGaN/GaN HEMTs operating over 200 °C. GaN/AlGaN/GaN HEMTs, with the extremely low source resistance were fabricated by multiple ion implantation, precisely controlled ion‐implanted (I/I) resistors and Schottky barrier diodes were integrated on the silicon substrate. The GaN cap layer on the AlGaN was grown to decrease the gate leakage current and current collapse for AlGaN/GaN HEMTs. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Study on the effect of the relative position of the phosphor layer in the LED package on the high power LED lifetime
Authors: Hwang Jung‐Ha , Kim Yu‐Dong , Kim Jae‐Wook , Jung Su‐Jung , Kwon Ho‐Ki , Oh Tchang‐Hun
Published: May 2010

For the case of the white LED (phosphor converted), the temperature affects phosphor in addition to chip and package. The heat can cause the decrease of the phosphor performance as well as the irreversible damage to the phosphor. In this study, the effect of phosphor thermal configuration on the degradation rate has been investigated experimentally and verified by the theoretical simulations. Two different configurations have been tested. One is die‐contact phosphor layer and the other is remote case. The experimental result shows that the LEDs of the die‐contact phosphor layers exhibit lower degradation rate than those of the remote phosphor layers. The thermal simulation considering the heat generation from the phosphor (energy converting loss) shows similar results. The temperature of remote phosphor layer is higher than the die‐contact case. High temperature causes rapid degradation of phosphor. As the power consumption of LEDs increases, the heat generation from the phosphor becomes no more negligible. For the higher performance and longer lifetime, we have to consider phosphor layer as the heat generator and design the layer with sufficient thermal paths. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Piezoelectric actuated epitaxially grown AlGaN/GaN‐resonators
Authors: Niebelschuetz F. , Brueckner K. , Tonisch K. , Stephan R. , Cimalla V. , Ambacher O. , Hein M. A.
Published: May 2010

In this work we present a novel concept of piezoelectrically actuated MEMS resonators based on AlGaN/GaN‐heterostructures. The 2DEG, which is confined at the AlGaN/GaN interface, serves as back electrode for piezoelectric actuation and read‐out. Using the inverse piezoelectric effect longitudinal in‐plane mechanical oscillations could be exited by applying a RF signal to the drive contacts. Through the charges, which were generated by the direct piezoelectric effect a sensor signal could be detected at the sense contacts of the integrated resonator structure. This enables the measurement of longitudinal resonant frequencies up to the 4th mode with values from 3 to 63 MHz. The investigations were carried out in various ambient pressure conditions, which exemplarily demonstrate the sensitivity of the quality factor to environmental parameters. Thereby the AlGaN/GaN‐resonators showed the highest sensitivity in the region of viscous damping, which leads to the possibility of sensor applications concerning the property determination of gaseous or even liquid surrounding conditions. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dissolution Study of Salt of Long Chain Fatty Acids (Soap Scum) in Surfactant Solutions. Part II: Kinetics of Dissolution
Authors: Soontravanich Sukhwan , Landrum J. Grant , Shobe Sarah A. , Waite Chase M. , Scamehorn John F. , Sabatini David A. , Scheuing David R.
Published: May 2010

A study of the dissolution kinetics of soap scum, calcium octadecanoate (Ca(C18)2), by aqueous solutions was carried out by measuring the rate of dissolution of Ca(C18)2 using a flow cell apparatus. These solutions contained three different types of surfactants: dimethyldodecylamine oxide (DDAO), sodium dodecyl sulfate (SDS), or octyl polyglycoside (C8APG), in the presence of a chelating agent, disodium ethylenediaminetetraacetate (Na2EDTA). The resulting rate of dissolution corresponds well with the equilibrium solubility obtained in the part I of this series even though the dissolution is rate limited (far from equilibrium). High rates of Ca(C18)2 dissolution are achieved in solutions of zwitterionic DDAO or nonionic C8APG with Na2EDTA at high pH. From rate analysis, the Ca(C18)2 dissolution was found to be surface‐reaction limited rather than limited by solution processes or wettability.
The Planetary Nebula Luminosity Function: Pieces of the Puzzle
Authors: Ciardullo R.
Published: May 2010

Extragalactic surveys in the emission line of [O iii] λ5007 have provided us with the absolute line strengths of large, homogeneous sets of planetary nebulae. These data have been used to address a host of problems, from the measurement of the extragalactic distance scale, to the study of stellar populations. I review our current understanding of the [O iii] planetary nebula luminosity function (PNLF), and discuss some of the physical processes that effect its structure. I also describe the features of the Hα PNLF, a function that, upon first glance, looks similar to the [O iii] PNLF, but which includes a very different set of objects. Finally, I discuss recent measurements of α, the number of PNe found in a stellar population, normalized to that population's bolometric luminosity. I show that, contrary to expectations, the values of α found in actively star-forming spirals are essentially the same as those measured in late-type elliptical and lenticular systems. I discuss how this result sheds light on the physics of the planetary nebula phenomenon.
A FUSE View of Winds from the Central Stars of Planetary Nebulae
Authors: Guerrero Martín A. , Ramos-Larios Gerardo , Massa Derck
Published: May 2010

Since the IUE satellite produced a vast collection of high-resolution UV spectra of the central stars of planetary nebulae (CSPNe), there has not been any further systematic study of the stellar winds of these stars. The high spectral resolution, sensitivity and large number of archival observations in the FUSE archive allow the study of the stellar winds of CSPNe in the far-UV domain where lines of species spanning a wide excitation range can be observed. We present here a preliminary analysis of the P Cygni profiles of a sample of ∼60 CSPNe observed by FUSE. P Cygni profiles providing evidence for fast stellar winds with velocities between 200 and 4300 km s−1 have been found in 40 CSPNe. In many cases, this is the first time that fast stellar winds have been reported for these planetary nebulae (PNe). A detailed study of these far-UV spectra is on-going.
Searching for Faint Planetary Nebulae Using the Digital Sky Survey
Authors: Jacoby George H. , Kronberger Matthias , Patchick Dana , Teutsch Philipp , Saloranta Jaakko , Howell Michael , Crisp Richard , Riddle Dave , Acker Agnès , Frew David J. , Parker Quentin A.
Published: May 2010

Recent Hα surveys such as SHS and IPHAS have improved the completeness of the Galactic planetary nebula (PN) census. We now know of ∼3000 PNe in the Galaxy, but this is far short of most estimates, typically ~25 000 or more for the total population. The size of the Galactic PN population is required to derive an accurate estimate of the chemical enrichment rates of nitrogen, carbon, and helium. In addition, a high PN count (>20 000) is strong evidence that most main-sequence stars of mass 1–8 M⊙ will go through a PN phase, while a low count (<10 000) argues that special conditions (e.g. close binary interactions) are required to form a PN. We describe a technique for finding hundreds more PNe using the existing data collections of the digital sky surveys, thereby improving the census of Galactic PNe.
Morphological Structures of Planetary Nebulae
Authors: Kwok Sun
Published: May 2010

Since various structural components of planetary nebulae (PN) manifest themselves differently, a combination of optical, infrared, submillimetre and radio techniques is needed to derive a complete picture of planetary nebulae. The effects of projection can also make derivation of the true 3-D structure difficult. Using a number of examples, we show that bipolar and multipolar nebulae are much more common than usually inferred from morphological classifications of apparent structures of planetary nebulae. We put forward a new hypothesis that the bipolar and multipolar lobes of PN are not regions of high-density ejected matter, but the result of ionization and illumination. The visible bright regions are in fact volumes of low density (cleared by high-velocity outflows), through which UV photons are being channelled. We suggest that multipolar nebulae with similar lobe sizes are not caused by simultaneous ejection of matter in several directions, but by leakage of UV photons in those directions.
Measuring Mass-Loss Evolution at the Tip of the Asymptotic Giant Branch
Authors: Sandin C. , Roth M. M. , Schönberner D.
Published: May 2010

In the final stages of stellar evolution low- to intermediate-mass stars lose their envelope in increasingly massive stellar winds. Such winds affect the interstellar medium and the galactic chemical evolution as well as the circumstellar envelope where planetary nebulae form subsequently. Characteristics of this mass loss depend on both stellar properties and properties of gas and dust in the wind formation region. In this paper we present an approach towards studies of mass loss using both observations and models, focussing on the stage where the stellar envelope is nearly empty of mass. In a recent study we measure the mass-loss evolution, and other properties, of four planetary nebulae in the Galactic disk. Specifically we use the method of integral field spectroscopy on faint halos, which are found outside the much brighter central parts of a planetary nebula. We begin with a brief comparison between our and other observational methods to determine mass-loss rates in order to illustrate how they differ and complement each other. An advantage of our method is that it measures the gas component directly requiring no assumptions of properties of dust in the wind. Thereafter we present our observational approach in more detail in terms of its validity and its assumptions. In the second part of this paper we discuss capabilities and assumptions of current models of stellar winds. We propose and discuss improvements to such models that will allow meaningful comparisons with our observations. Currently the physically most complete models include too little mass in the model domain to permit a formation of winds with as high mass-loss rates as our observations show.
Rebrightening of Planetary Nebulae Through Interaction with the Interstellar Medium
Authors: Wareing C. J.
Published: May 2010

The interaction of planetary nebulae (PNe) with the interstellar medium (ISM) as they move through it is now acknowledged to be a major shaping effect not just for ancient and large PNe, but also for relatively young PNe with high-speed central stars. The most common effect is a rebrightening as the PN shell interacts with a pre-existing bow-shock structure formed during the previous evolutionary phase of the central star. In this review we consider this rebrightening in detail for the first time and discuss its origins, highlighting some observed examples. We go on to discuss the AGB progenitor stars, reviewing the evidence for bow-shock structures, and consider the progeny of rebrightened PNe — strongly disrupted objects which bear very little resemblance to typical PNe. Sh 2-68 is inferred to be perhaps the only documented case so far of such a PN.
The acid test of v-ATPase function
Authors: Short Ben
Published: May 2010

The vesicular protein complex has a dual role in sorting and degrading neuronal proteins.
Inke Näthke: The ABCs of APC
Authors: Sedwick Caitlin
Published: May 2010

Näthke investigates the many functions of adenomatous polyposis coli protein and its contribution to human disease.
Dcp2 phosphorylation by Ste20 modulates stress granule assembly and mRNA decay in Saccharomyces cerevisiae
Authors: Yoon Je-Hyun , Choi Eui-Ju , Parker Roy
Published: May 2010

Translation and messenger RNA (mRNA) degradation are important sites of gene regulation, particularly during stress where translation and mRNA degradation are reprogrammed to stabilize bulk mRNAs and to preferentially translate mRNAs required for the stress response. During stress, untranslating mRNAs accumulate both in processing bodies (P-bodies), which contain some translation repressors and the mRNA degradation machinery, and in stress granules, which contain mRNAs stalled in translation initiation. How signal transduction pathways impinge on proteins modulating P-body and stress granule formation and function is unknown. We show that during stress in Saccharomyces cerevisiae, Dcp2 is phosphorylated on serine 137 by the Ste20 kinase. Phosphorylation of Dcp2 affects the decay of some mRNAs and is required for Dcp2 accumulation in P-bodies and specific protein interactions of Dcp2 and for efficient formation of stress granules. These results demonstrate that Ste20 has an unexpected role in the modulation of mRNA decay and translation and that phosphorylation of Dcp2 is an important control point for mRNA decapping.
Multiple mechanisms collectively regulate clathrin-mediated endocytosis of the epidermal growth factor receptor
Authors: Goh Lai Kuan , Huang Fangtian , Kim Woong , Gygi Steven , Sorkin Alexander
Published: May 2010

Endocytosis of the epidermal growth factor receptor (EGFR) is important for the regulation of EGFR signaling. However, EGFR endocytosis mechanisms are poorly understood, which precludes development of approaches to specifically inhibit EGFR endocytosis and analyze its impact on signaling. Using a combination of receptor mutagenesis and RNA interference, we demonstrate that clathrin-dependent internalization of activated EGFR is regulated by four mechanisms, which function in a redundant and cooperative fashion. These mechanisms involve ubiquitination of the receptor kinase domain, the clathrin adaptor complex AP-2, the Grb2 adaptor protein, and three C-terminal lysine residues (K1155, K1158, and K1164), which are acetylated, a novel posttranslational modification for the EGFR. Based on these findings, the first internalization-defective EGFR mutant with functional kinase and normal tyrosine phosphorylation was generated. Analysis of the signaling kinetics of this mutant revealed that EGFR internalization is required for the sustained activation of protein kinase B/AKT but not for the activation of mitogen-activated protein kinase.
Metadata matters: access to image data in the real world
Authors: Linkert Melissa , Rueden Curtis T. , Allan Chris , Burel Jean-Marie , Moore Will , Patterson Andrew , Loranger Brian , Moore Josh , Neves Carlos , MacDonald Donald , Tarkowska Aleksandra , Sticco Caitlin , Hill Emma , Rossner Mike , Eliceiri Kevin W. , Swedlow Jason R.
Published: May 2010

Data sharing is important in the biological sciences to prevent duplication of effort, to promote scientific integrity, and to facilitate and disseminate scientific discovery. Sharing requires centralized repositories, and submission to and utility of these resources require common data formats. This is particularly challenging for multidimensional microscopy image data, which are acquired from a variety of platforms with a myriad of proprietary file formats (PFFs). In this paper, we describe an open standard format that we have developed for microscopy image data. We call on the community to use open image data standards and to insist that all imaging platforms support these file formats. This will build the foundation for an open image data repository.