bluuebunny/crossref_metadata_2025 huggingface dataset:
Prevalence of anxiety disorders and anxiety subtypes in patients with Parkinson's disease
Authors: Pontone Gregory M. , Williams James R. , Anderson Karen E. , Chase Gary , Goldstein Susanne A. , Grill Stephen , Hirsch Elaina S. , Lehmann Susan , Little John T. , Margolis Russell L. , Rabins Peter V. , Weiss Howard D. , Marsh Laura
Published: May 2009

Anxiety disorders are common in Parkinson's disease (PD), but are not well characterized. This study determined the prevalence and clinical correlates of all DSM‐IV‐TR anxiety disorder diagnoses in a sample of 127 subjects with idiopathic PD who underwent comprehensive assessments administered by a psychiatrist and neurologist. A panel of six psychiatrists with expertise in geriatric psychiatry and/or movement disorders established by consensus all psychiatric diagnoses. Current and lifetime prevalence of at least one anxiety disorder diagnosis was 43% (n = 55) and 49% (n = 63), respectively. Anxiety disorder not otherwise specified, a DSM diagnosis used for anxiety disturbances not meeting criteria for defined subtypes, was the most common diagnosis (30% lifetime prevalence, n = 38). Compared with nonanxious subjects, panic disorder (n = 13) was associated with earlier age of PD onset [50.3 (12.2) vs. 61.0 (13.7) years,P< 0.01], higher rates of motor fluctuations [77% (10/13) vs. 39% (25/64),P= 0.01] and morning dystonia [38% (5/13) vs. 13% (8/62),P< 0.03]. This high prevalence of anxiety disorders, including disturbances often not meeting conventional diagnostic criteria, suggests that anxiety in PD is likely underdiagnosed and undertreated and refined characterization of anxiety disorders in PD is needed. In addition, certain anxiety subtypes may be clinically useful markers associated with disease impact in PD. © 2009 Movement Disorder Society
Exploring indicators for pain rehabilitation: A Delphi study using a multidisciplinary expert panel
Authors: Skjutar Åsa , Christensson Kyllike , Müllersdorf Maria
Published: May 2009

Objective: Lack of referral guidelines can cause delayed or even non‐existent rehabilitation for chronic pain patients. Indicators signalling the need for interventions could counteract this delay for pain rehabilitation and thereby prevent deteriorating patient health. This study aimed to explore the indicators of need for pain rehabilitation using a multidisciplinary expert panel working with pain rehabilitation.

Methods: A three‐round Delphi study was conducted with a multidisciplinary expert panel (n = 23), each representing one pain rehabilitation unit in Sweden. The expert panel produced indicators, which were then ranked using a four‐point Likert scale.

Results: Twenty multi‐faceted indicators for pain rehabilitation were identified. A major part concerned patient problems with activity level, catastrophizing, coping, existential problems, fear avoidance, high pain rating, medication, mental health, motivation, no pain relief, pain spread/increase, psychosocial problems combined with activity problems, psychosocial problems, recovery, and reduced physical function. Furthermore, indicators concerned demographic factors, sick leave, situation in primary health care and work. Finally, tacit knowledge was pointed out as an indicator. The results support previous research but also bring out less quantifiable indicators, such as relying on tacit knowledge while assessing a patient's need for rehabilitation.

Conclusion: The indicators for pain rehabilitation were comprehensive, pointing out that needs assessment is complex. Despite reaching consensus on 19 out of 20 indicators, further research is needed to deepen knowledge in this area and to secure a fair assessment of a patient's need for pain rehabilitation. Copyright © 2009 John Wiley & Sons, Ltd.
Effect of spatial variability of cross‐correlated soil properties on bearing capacity of strip footing
Authors: Cho Sung Eun , Park Hyung Choon
Published: May 2009

Geotechnical engineering problems are characterized by many sources of uncertainty. Some of these sources are connected to the uncertainties of soil properties involved in the analysis. In this paper, a numerical procedure for a probabilistic analysis that considers the spatial variability of cross‐correlated soil properties is presented and applied to study the bearing capacity of spatially random soil with different autocorrelation distances in the vertical and horizontal directions. The approach integrates a commercial finite difference method and random field theory into the framework of a probabilistic analysis. Two‐dimensional cross‐correlated non‐Gaussian random fields are generated based on a Karhunen–Loève expansion in a manner consistent with a specified marginal distribution function, an autocorrelation function, and cross‐correlation coefficients. A Monte Carlo simulation is then used to determine the statistical response based on the random fields. A series of analyses was performed to study the effects of uncertainty due to the spatial heterogeneity on the bearing capacity of a rough strip footing. The simulations provide insight into the application of uncertainty treatment to geotechnical problems and show the importance of the spatial variability of soil properties with regard to the outcome of a probabilistic assessment. Copyright © 2009 John Wiley & Sons, Ltd.
Gmsh: A 3‐D finite element mesh generator with built‐in pre‐ and post‐processing facilities
Authors: Geuzaine Christophe , Remacle Jean‐François
Published: May 2009

Gmsh is an open‐source 3‐D finite element grid generator with a build‐in CAD engine and post‐processor. Its design goal is to provide a fast, light and user‐friendly meshing tool with parametric input and advanced visualization capabilities. This paper presents the overall philosophy, the main design choices and some of the original algorithms implemented in Gmsh. Copyright © 2009 John Wiley & Sons, Ltd.
Segregated by neighbourhoods? A portrait of ethnic diversity in the neighbourhoods of the Accra Metropolitan Area, Ghana
Authors: Agyei‐Mensah Samuel , Owusu George
Published: May 2009

Studies of urban ethnicity have portrayed ethnic groups as initially concentrating in locations where they live in relatively exclusive residential areas containing few members of other groups. This concentration into ethnic enclaves is commonly regarded as a result of disadvantage and discrimination in the labour and housing markets, coupled with a desire for residential concentration to promote and guarantee group cultural, socioeconomic and physical security. To what extent do the neighbourhoods of Accra Metropolitan Area reflect these urban ethnicity patterns, and what are the factors shaping the concentration of ethnic groups in the city? Using the Location Quotient Index based on census data, the paper examines the degree of ethnic diversity and concentration in the neighbourhoods of Accra. The findings of the study reveal that Accra is not following a Western model of segregation, neither is there a single model of African segregation, but rather many African trajectories. Economic segregation is the organising force underlying residential segregation in Accra, and this operates through several social markers, one of which remains the ethnic history of migration to Accra. Copyright © 2009 John Wiley & Sons, Ltd.
Bringing norms back in: a theoretical and empirical discussion of their importance for understanding demographic behaviour
Authors: Liefbroer Aart C. , Billari Francesco C.
Published: May 2009

Although the life‐course perspective emphasizes the importance of the concept of social norms for understanding demographic choices, the usefulness of this concept is heavily debated. In particular, it has been questioned whether social norms are still important in post‐modern societies, and whether societal expectations can really be called norms if no sanctions are attached to them. In this article, we review the theoretical and empirical literature, highlight the potential usefulness of the concept, and illustrate its importance by presenting empirical data on the existence of norms concerning demographic choices in The Netherlands, one of the most individualized countries in the world. Copyright © 2009 John Wiley & Sons, Ltd.
Internal migration in Britain, 2000–01, examined through an area classification framework
Authors: Dennett Adam , Stillwell John
Published: May 2009

This paper explores the age variations in origin–destination migration data from the 2001 UK Census. It does so using a national district classification as a framework for summarising what is a series of matrices, each containing very large numbers of cells. The results demonstrate how migration propensities and patterns vary between different types of district, providing new insights into the processes through which the population is redistributed throughout Great Britain. Copyright © 2009 John Wiley & Sons, Ltd.
Who's crossing the border: new data on undocumented immigrants to the United States
Authors: Weeks John R. , Stoler Justin , Jankowski Piotr
Published: May 2009

The majority of undocumented immigrants to the United States enter through the southern border and most are from Mexico. Researchers in the US have been able to create estimates of how many unauthorised immigrants come from each country, but there has been little research on the geographical origins of immigrants from within Mexico. In this research we make use of a unique unduplicated file of people detained at or near the border by the US Border Patrol during the years 1999 to 2006. By focusing especially on the population aged 20–34, we are able to create a migration propensity index, which is the ratio of detainees from each state in Mexico to the population aged 20–34 in that state. The analysis of this index confirms the few other sources of information suggesting that migration from Mexico to the US is increasingly occurring from the more southern, indigenous states. A multiple regression analysis of the migration propensity index and state‐level variables finds that the death rate from accidents and violence among men aged 20–34 is the single most important predictor of a state's migration propensity index. This is related to a variety of factors indicating that migrants come from states with the poorest economic infrastructure. We discuss the implications of these shifts for both receiving and sending communities. Copyright © 2009 John Wiley & Sons, Ltd.
Studies of the EPR parameters and defect structure for tetrahedral Fe3+ centers in zinc oxide
Authors: Yang Zi‐Yuan
Published: May 2009

The relations between the electron paramagnetic resonance (EPR) parameters and crystal structure of Fe3+:ZnO crystals have been established. On the basis of this, the EPR parameters D, (a‐F) and the zero‐field splitting (ZFS) δ1, δ2 of the ground state for Fe3+ in Fe3+:ZnO crystals are theoretically investigated using the complete diagonalization method (CDM). The theoretical second‐order EPR parameter D, the fourth‐order EPR parameter (a‐F), and the ZFS of the ground state: δ1, δ2 for Fe3+ in Fe3+:ZnO yield a good agreement with experimental findings when the three O2– ions below the Fe3+ ion rotate by Δθ in the range 0.475–0.562° away from the [111] axis. Hence, the local structure distortion effect plays an important role in explaining the spectroscopic properties of Fe3+ ions in Fe3+:ZnO crystals. Our approach takes into account the spin–orbit (SO) interaction as well as the spin–spin (SS), spin–other–orbit (SOO), and orbit–orbit (OO) interactions omitted in previous studies. This shows that although the SO interaction is the most important one, the contributions to the EPR parameters from the other three interactions are appreciable and should not be omitted, especially for the EPR parameter D. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
First‐principles calculations of structural, elastic and electronic properties of Ni2MnZ (Z = Al, Ga and In) Heusler alloys
Authors: Rached H. , Rached D. , Khenata R. , Reshak Ali H. , Rabah M.
Published: May 2009

We have performed ab‐initio density‐functional theory self‐consistent calculations using the full‐potential linear muffin‐tin orbital method within local spin‐density approximation to study the electronic and magnetic properties of Ni2MnZ (Z = Al, Ga and In) in L21 structure. The magnetic phase stability is determined from the total energy calculations for both the nonmagnetic (NM) and magnetic (M) phases. The theoretical calculations clearly indicate that at both ambient and high pressures, the magnetic phase is more stable than the nonmagnetic phase. The elastic constants at equilibrium are also determined. We derived the bulk and shear moduli, Young's modulus, and Poisson's ratio. The Debye temperature of Ni2MnZ was estimated from the average sound velocity. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electronic and elastic properties of perovskite‐like W3NiC, W3NiN and Co3WC from first‐principles calculations
Authors: Suetin Dmitrii V. , Bannikov Vyacheslav V. , Shein Igor R. , Ivanovskii Alexander L.
Published: May 2009

We have performed ab initio total energy calculations using the full‐potential linearized augmented plane wave (FP‐LAPW) method with the generalized gradient approximation (GGA) for the exchange–correlation potential to investigate structural, elastic, cohesive, electronic and magnetic properties of the tungsten‐containing perovskite‐like phases W3NiC, W3NiN and Co3WC. The optimized lattice parameters, independent elastic constants (Cij), bulk moduli (B) and shear moduli (G), as well as densities of electronic states and cohesive and formation energies are obtained and analyzed for the first time. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Light emitting FET based‐on spatially selective doping of Eu in AlGaN/GaN HEMT
Authors: Okada Hiroshi , Takemoto Kazumasa , Oikawa Fumitake , Furukawa Yuzo , Wakahara Akihiro , Sato Shin‐ichiro , Ohshima Takeshi
Published: May 2009

Light emitting field effect transistor (FET) based‐on AlGaN/GaN high electron mobility transistor (HEMT) structure with spatially selective doping of rare‐earth ions (REIs) as a luminescence center in the channel is proposed and investigated. Fabricated device showed excellent I –V characteristics as a transistor with gate control. By applying a drain bias of 20 V, red emission suggesting a luminescence from Eu ion was clearly observed. Applying a negative bias to the Schottky gate decreased the luminescence intensity (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Characterization of asymmetric GaN/InGaN multiple quantum well
Authors: Chen Z. Z. , Qi S. L. , Liu P. , Yu T. J. , Wang C. D. , He Z. K. , Tong Y. Z. , Pan Y. B. , Hao M. S. , Zhang G. Y.
Published: May 2009

The microstructure and electronic structure of the asymmetric GaN/InGaN multiple quantum well (MQW) light emitting diodes are characterized by transmission electron microscope (TEM), cathodoluminescence (CL) and capacitance‐voltage (C‐V) measurements. In TEM images, the asymmetric structure of InGaN/GaN MQW are observed as designed with different width of QWs and barriers, and indium content in QWs as well. In high‐resolution TEM images, the InGaN quantum wells and GaN barriers show the same lattice constant, and some degradation can be seen at the bottom of each InGaN QW. There are two emission peaks, 450 and 530 nm in CL spectrum, similar to the ones in electroluminescence spectrum. The double emission peaks are assigned to the irradiative recombination in different InGaN QWs. From the C‐V data, the apparent carrier concentration in the asymmetric MQW is calculated. There are five obvious peaks which are well explained by an energy band scheme of InGaN/GaN MQW. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Diffusion and recombination of degenerate carrier plasma in GaN
Authors: Malinauskas Tadas , Jarasiunas Kestutis , Heuken Michael , Scholz Ferdinand , Brückner Peter
Published: May 2009

The carrier diffusion and recombination were investigated by light induced transient grating technique (LITG) in a HVPE grown GaN at intense band‐to‐band excitation. The given measurements in high structural quality layers revealed the features of an intrinsic crystal – carrier‐density dependent recombination and diffusion. It was found that ambipolar carrier diffusion coefficient D and carrier lifetime τ were dependent on excitation intensity and therefore varied during the grating decay. The values of D = 1.5 cm2/s and τ = 3.8 ns were found for carrier densities ∼1018 cm–3, while at the highest excitation used (n∼1020 cm–3) the D value reached 4.1 cm2/s, and τ decreased to 1.3 ns. The numerical modelling of carrier dynamics confirmed that the observed increase of diffusion coefficient with carrier density was due to degeneracy of carrier plasma, while short carrier lifetime at high carrier density was ruled by a bimolecular recombination. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Impact of the field induced polarization space‐charge on the characteristics of AlGaN/GaN HEMT: Self‐consistent simulation study
Authors: Balaz D. , Kalna K. , Kuball M. , Uren M. J. , Asenov A.
Published: May 2009

Using self‐consistent numerical simulation we have studied the impact of the field induced polarization on the characteristics of AlGaN/GaN high electron mobility transistors (HEMTs). The strain induced by external electric fields is on top of the built‐in strain due to lattice mismatch. It has been suggested that this additional strain can play a role in device degradation and failure (J. Joh and J. del Alamo, Mechanisms for Electrical Degradation of GaN High‐Electron Mobility Transistors, IEDM Tech. Dig., pp. 415–418, Dec. (2006) [1]). The study is carried out using commercial TCAD tools carefully calibrated against the measured characteristics of 0.25 μm physical gate length transistors. A coupled model for piezoelectric materials, including the impact of the field, is used to determine the strain and thus the polarization in the device. The spatial charge distribution is derived from the gradient of the polarization and is fed back self‐consistently to the simulator. Results with and without the field‐induced polarization are compared and discussed. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Tunneling effects in short period strained AlN/GaN superlattices
Authors: Valcheva E. , Kirilov K. , Monemar B. , Amano H. , Akasaki I.
Published: May 2009

We study electronic conduction of short period strained GaN/AlN superlattices. The mechanisms of current transport perpendicular to the layers were studied, with an emphasis on the elastic and inelastic tunneling through the AlN barriers. Electron transport as a function of temperature is examined in I‐V, G‐V (first derivative dI/dV). The current and the conductance show nonlinear oscillatory character. The observed characteristics are interpreted as sequential resonant tunneling through AlN barriers and reveal negative differential conductivity (NDC). (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modeling analysis of AlN and AlGaN HVPE
Authors: Segal A. S. , Bazarevskiy D. S. , Bogdanov M. V. , Yakovlev E. V.
Published: May 2009

Comprehensive model of AlN and AlGaN HVPE is developed. The model combines detailed description of the transport processes and quasi‐thermodynamic model of surface kinetics at the Al/Ga metal surfaces and AlN/AlGaN crystal surfaces. It is shown with the model that HCl dominantly converts into trichloride AlCl3 in the Al source but into monochloride GaCl in the Ga source. Then, AlN grows from AlCl3 under essentially non‐equilibrium conditions while GaN – from GaCl under near‐equilibrium conditions. The revealed differences between the AlN and GaN growth features explain many experimentally observed phenomena, including a sharp saturated behavior of the AlN growth rate in variation of the precursors flow rates and a strong effect of carrier H2 on the AlGaN composition. Generally, the model predicts a high sensitivity of the AlGaN composition to variation of the species flow rates due to their effect on the Ga incorporation. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Investigation of polarity dependent InN{0001} decomposition in N2 and H2 ambient
Authors: Togashi R. , Kamoshita T. , Adachi H. , Murakami H. , Kumagai Y. , Koukitu A.
Published: May 2009

The polarity dependence of decomposition of the (0001) In‐ and (000$ \bar 1 $) N‐polarity InN layers grown by hydride vapor phase epitaxy (HVPE) on freestanding GaN substrates was investigated. In flowing N2, In‐ and N‐polarity InN layers start to decompose over 550 and 610 °C, respectively. Therefore, the N‐polarity InN layer is more stable than the In‐polarity InN layer. On the other hand, in flowing H2, InN layers of both polarities start to react with H2 at a low temperature of 350 °C leaving In droplets on the surfaces. Further more, the decomposition rate of the N‐polarity InN layer is larger than that of the In‐polarity InN layer below approximately 450 °C, while the decomposition rate of the In‐polarity InN layer is larger than that of the N‐polarity InN above 450 °C. An Arrhenius plot of the decomposition rates revealed that the activation energies, EA, for the decomposition reactions of In‐ and N‐ polarity InN layers are 168 and 107 kJ/mol, respectively, which are much smaller than that for GaN and AlN decomposition. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Metastable cubic InN layers on GaAs (001) substrates grown by MBE: Growth condition and crystal structure
Authors: Sanorpim Sakuntam , Jantawongrit Papaporn , Kuntharin Sman , Thanachayanont Chanchana , Nakamura Teruyuki , Katayama Ryuji , Onabe Kentaro
Published: May 2009

Transmission electron microscopy and high resolution X‐ray diffraction were applied to characterize the crystal structure and its modification in c‐InN layers on GaAs (001) substrates grown by rf‐plasma assisted molecular beam epitaxy. The layer quality was shown to depend on growth conditions, namely In‐ and N‐rich conditions. The best quality of c‐InN layers was achieved by “stoichiometric” growth under the In‐rich condition, resulting in In‐rich layers with a small amount of hexagonal‐phase inclusion (∼8%). On the other hand, nucleation and growth of N‐rich layers are shown to result in a high density of stacking faults which drastically decreases toward the InN surface. It is argued that the presence of stacking faults contributes to the structural modification in these layers. We found that the existence of a structural modification from cubic to mixed cubic/hexagonal phase in microstructure of the N‐rich layers exhibit higher hexagonal‐phase incorporation than that of the In‐rich layers. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Photoluminescence and excitation spectrum of Mg‐doped p‐type AlXGa1–XN
Authors: Suzuki M. , Sawai S. , Fukui K. , Nagamatsu K. , Amano H.
Published: May 2009

We have been measured the near band edge photoluminescence (PL) and photoluminescence excitation (PLE) spectra of Mg doped AlGaN. PL and PLE peak energies were almost corresponding to those of undoped AlGaN. From the temperature dependent measurement of the PL spectra, the PL peak energy shift as a function of temperature showed S ‐shaped behaviour. These results suggest that the mechanisms of the near band edge PL of AlGaN:Mg are basically similar to those of undoped AlGaN. Using the known spectral feature of undoped AlGaN which consists of main and LO phonon replica emission bands at even interval energy and same line width, the spectral decomposition of the PL spectrum reveals an additional band which is expected as the transition to the acceptor level arising from Mg doping. The temperature dependences of its peak energy and intensity suggest relative temperature shift of the acceptor level and also may imply the existence of another relaxation pathway. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
MOVPE growth of InN: a comparison between a horizontal and a vertical reactor
Authors: Liu Yuhuai , Kimura Takeshi , Shimada Taka‐aki , Hirata Masaki , Wakaba Masaki , Nakao Masashi , Ji Shi‐Yang , Matsuoka Takashi
Published: May 2009

The MOVPE growth of InN by a horizontal reactor is compared with that by a vertical reactor. The phase diagram does not almost depend on the reactor structure, but rather the parameters such as V/III ratio and the growth temperature. The growth rate of InN in the horizontal reactor significantly increases in comparison with the vertical reactor due to the reduction of the stagnant layer thickness, the increases in the source supply to the substrate surface and the high concentration of source gases by narrowing flow channel. For the horizontal reactor, the polycrystalline phase appeared in the case of the low carrier‐gas flow‐rate and disappeared for the high carrier‐gas flow‐rate. These data suggest that increasing the carrier gas flow rate can suppress the gas phase reactions. In the case of the horizontal reactor, InN can be obtained at temperatures as high as 625 °C, compared with the maximum growth temperature of 575 °C in the vertical reactor. But the growth rates significantly decrease above 600 °C. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Epitaxy and characterisation of AlInGaN heterostructures for HEMT application
Authors: Khoshroo L. Rahimzadeh , Mauder C. , Behmenburg H. , Woitok J. , Zander W. , Gruis J. , Reuters B. , Schubert J. , Vescan A. , Heuken M. , Kalisch H. , Jansen R. H.
Published: May 2009

In this paper we report on the growth and charcterization of quaternary AlInGaN/AlN/GaN heterostructures, spanning a range from 26% to 82% AlN, 4% to 18% InN and 0% to 70% GaN in the barrier layer. All samples were grown in AIXTRON metal organic vapor phase epitaxy (MOVPE) reactors on 2″ sapphire substrates. Sample characterisation was performed using high resolution X‐ray diffraction (HRXRD), X‐ray reflection (XRR), photoluminescence spectroscopy (PL), atomic force microscopy (AFM) and Rutherford backscattering (RBS). Inductive sheet resistance measurements and Hall measurements in van der Pauw geometry provided electrical characterization. AFM measurements show closed layers, in HRXRD measurements pendellösung oscillations are visible even in asymmetric reciprocal space maps. Mobility and sheet carrier concentration reach state of the art values currently achieved for ternary structures showing the high degree of tunability in the quaternary nitride system. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dependence of annealing temperature on electrical properties of GaN MIS capacitors
Authors: Shibata E. , Kaneko M. , Kikawa J. , Horiuchi Y. , Otake H. , Chikamatsu K. , Yamaguchi A. , Fujishima T. , Nanishi Y.
Published: May 2009

We used capacitance‐voltage (C‐V) and capacitance deep‐level transient spectroscopy (C‐DLTS) methods to study the electrical properties of GaN metal‐insulator‐semiconductor (MIS) capacitors. The MIS capacitors consisted of SiO2/GaN, SiN/GaN, or SiO2/SiN/GaN, respectively, and annealing temperature was varied. From the C‐V characteristics, samples annealed at 400 °C had a large hysteresis, an insufficient accumulation in the measured bias range, and a specific ledge. These features relate with traps and fixed charge. For the SiO2/GaN and the SiO2/SiN/GaN interface, these features improved when the annealing temperature exceeded 600 °C. On the other hand, it is confirmed that the annealing treatment up to 800 °C was insufficient in the SiN/GaN interface.

From the C‐DLTS analysis, a common trap with an activation energy of 0.7‐0.8 eV was observed from all the MIS capacitors, suggesting the existence of complexes of Si and surface defect on GaN. In the SiO2/GaN MIS capacitor annealed above 600 °C, traps with an activation energy of 50, 150, 180, and 630 meV were observed. The intensities of these peaks decreased with increasing annealing temperature and it is considered that they correlate with the improvement of depletion behavior. A specific trap with an activation energy of 0.32 eV was observed from SiN/GaN MIS capacitor and it agreed with that of the trap related to ledge estimated from the C‐V characteristics. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of length biased sampling of unobserved sojourn times on the survival distribution when disease is screen detected
Authors: Kafadar Karen , Prorok Philip C.
Published: May 2009

Data can arise as a length‐biased sample rather than as a random sample; e.g. a sample of patients in hospitals or of network cable lines (experimental units with longer stays or longer lines have greater likelihoods of being sampled). The distribution arising from a single length‐biased sampling (LBS) time has been derived (e.g. (The Statistical Analysis of Discrete Time Events. Oxford Press: London, 1972)) and applies when the observed outcome relates to the random variable subjected to LBS. Zelen (Breast Cancer: Trends in Research and Treatment. Raven Press: New York, 1976; 287–301) noted that cases of disease detected from a screening program likewise form a length‐biased sample among all cases, since longer sojourn times afford greater likelihoods of being screen detected. In contrast to the samples on hospital stays and cable lines, however, the length‐biased sojourns (preclinical durations) cannot be observed, although their subsequent clinical durations (survival times) are. This article quantifies the effect of LBS of the sojourn times (or pre‐clinical durations) on the distribution of the observed clinical durations when cases undergo periodic screening for the early detection of disease. We show that, when preclinical and clinical durations are positively correlated, the mean, median, and quartiles of the distribution of the clinical duration from screen‐detected cases can be substantially inflated—even in the absence of any benefit on survival from the screening procedure. Screening studies that report mean survival time need to take account of the fact that, even in the absence of any real benefit, the mean survival among cases in the screen‐detected group will be longer than that among interval cases or among cases that arise in the control arm, above and beyond lead time bias, simply by virtue of the LBS phenomenon. Published in 2009 by John Wiley & Sons, Ltd.
Development and evaluation of a system enhancing Second Life to support synchronous role‐based collaborative learning
Authors: De Lucia Andrea , Francese Rita , Passero Ignazio , Tortora Genoveffa
Published: May 2009

Research and commercial interest toward 3D virtual worlds are recently growing because they probably represent the new direction for the next generation of web applications. Although these environments present several features that are useful for informal collaboration, structured collaboration is required to effectively use them in a working or in a didactical setting. This paper presents a system supporting synchronous collaborative learning by naturally enriching Learning Management System services with meeting management and multimedia features. Monitoring and moderation of discussions are also managed at a single group and at the teaching level. The Second Life (SL) environment has been integrated with twoad hocdeveloped Moodle plug‐ins and SL objects have been designed, modeled, and programmed to support synchronous role‐based collaborative activities. We also enriched SL with tools to support the capturing and displaying of textual information during collaborative sessions for successive retrieval. In addition, the multimedia support has been enhanced with functionalities for navigating multimedia contents. We also report on an empirical study aiming at evaluating the use of the proposed SL collaborative learning as compared with face‐to‐face group collaboration. Results show that the two approaches are statistically undistinguishable in terms of performance, comfort with communication, and overall satisfaction. Copyright © 2009 John Wiley & Sons, Ltd.
Investigating the role of CMMI with expanding company size for small‐ to medium‐sized enterprises
Authors: Lester N. G. , Wilkie F. G. , McFall D. , Ware M. P.
Published: May 2009

In this article we show how the results from software process appraisals of ten small‐ to medium‐sized software development enterprises demonstrate that as companies become larger they naturally use an increasing number of practices within the Capability Maturity Model Integration (CMMI®). The companies involved in this study had no CMMI®experience prior to this work. We identify those practices that tend to be best followed by both small‐ and medium‐sized enterprises and those that tend to be introduced as the company size increases from small to medium. We conclude that the CMMI®appears to have an inherent roadmap for process improvement, buried within its explicit structure of capability levels that is driven by company expansion. The results of this study can be used by organisations to plan process improvement as they expand in size and staff complement. We further show how our results are consistent with the European Union's definition of a ‘Small’ and a ‘Medium’ sized enterprise. Copyright © 2009 John Wiley & Sons, Ltd.
The relationship between: Miller's living systems theory and Beer's viable systems theory
Authors: Nechansky Helmut
Published: May 2009

The paper investigates if a living system according to Miller's living systems theory is a viable system according to Beer's viable systems theory and vice versa. Miller's and Beer's theories are briefly reviewed and translated into one cybernetic approach. The comparison of their functional and structural commonalties and differences shows: Miller's theory allows simple structures, below the scope of Beer's approach, which are nevertheless viable, as examples from biology, anthropology and economy show. Beer's viable systems can be derived form Miller's living systems theory, i.e. Beer deals only with issues of viability that emerge with complex living systems. Short considerations of large social units suggest that their structures are not unequivocally determined and may be viable while deviating from Beer's approach, too. Yet such structures can be derived from Miller's theory. It is concluded that Miller's living systems theory covers viability more completely than Beer's viable systems theory. Copyright © 2009 John Wiley & Sons, Ltd.
Prenatal phencyclidine exposure alters hippocampal cell proliferation in offspring rats
Authors: Tanimura Atsushi , Liu Juan , Namba Takashi , Seki Tatsunori , Matsubara Yoichiro , Itoh Masanobu , Suzuki Toshihito , Arai Heii
Published: May 2009

Multiple case reports have described pregnancy in phencyclidine hydrochloride (PCP) abusers. Characteristic clinical symptoms of PCP‐exposed infants have revealed neurobehavioral or physical abnormalities. We designed this study to evaluate whether chronic prenatal exposure to PCP during the last 2 weeks of gestation in rats produces alterations of hippocampal neurogenesis in offspring. Rats received repeated subcutaneous injection of PCP (5 mg/kg) once daily during the last 2 weeks of gestation. Control animals received subcutaneous injection of physiological saline during gestation. Dams receiving repeated PCP administrations showed markedly increased locomotor activities on days 1, 5, and 10 during the last 2 weeks of gestation. At 21 days after birth, 5‐bromo‐2′‐deoxyuridine (BrdU)‐positive cells of offspring were counted in the granule cell layer (GCL) and subgranular zone of the dentate gyrus. The numbers of BrdU‐positive cells in the GCL in male and female offspring of the PCP‐treated group were significantly increased by ∼77% compared with those from the control group. At 56 days, the number of surviving BrdU‐positive cells also remained to be increased by 74% in the GCL in PCP‐treated group. At 21 days, locomotor activities of offspring in the PCP‐treated group were significantly decreased by ∼30% compared with those in the control group. However, neuronal differentiation of newly formed cells and cell survival were not influenced at 5 weeks after BrdU injections. Some altered biochemical or physiological conditions of offspring from dams receiving repeated PCP injections during pregnancy could influence changes in cell proliferation in the GCL of offspring during early development. Changes to cell proliferation in the hippocampus may affect behavioral abnormalities during infancy in offspring. Synapse 63:729–736, 2009. © 2009 Wiley‐Liss, Inc.
First‐trimester fetal nasal bone length in an ethnic Chinese population
Authors: Sahota D. S. , Leung T. Y. , Chan L. W. , Law L. W. , Fung T. Y. , Chan O. K. , Lau T. K.
Published: May 2009

Objectives

To determine reference ranges of fetal nasal bone length (NBL) in a Chinese population and to assess the value of NBL measurement in screening for chromosomal defects in the first trimester.

Methods

In this prospective study the fetal profile was examined and the fetal NBL and crown–rump length (CRL) were measured in Chinese women presenting with singleton pregnancies for first‐trimester screening for aneuploidy between January 2004 and June 2007. Screening was performed on the basis of nuchal translucency (NT) measurement and maternal serum free β‐human chorionic gonadotropin and pregnancy‐associated plasma protein‐A levels.

Results

NBL was measured in 7543 fetuses, of which 7517 were euploid. The best fit equation for median NBL in euploid fetuses in relation to CRL was: NBL (mm) = 0.4593 + (0.0186 × CRL(mm)). The NBL for gestational age (GA, in days) was given by the equation NBL(mm) = 0.2392 + (0.0027 × GA). There was no correlation between log10(NBL multiples of the median (MoM)) and log10(NT MoM) in unaffected pregnancies (r = − 0.009; P = 0.43). Only two of the 11 cases with trisomy 21 had an NBL outside the 5th or 95th centiles of the reference range for euploid fetuses.

Conclusion

Reference ranges for NBL in a Chinese population suitable for screening for aneuploidy between 11 and 13 + 6 weeks' gestation have been derived. The NBL in Chinese fetuses is similar to that of other ethnic groups. However, unlike the determination of presence vs. absence of the nasal bone, NBL measurement is unlikely to further improve screening for aneuploidy. Copyright © 2009 ISUOG. Published by John Wiley & Sons, Ltd.
The Role of the Platelet‐Rich Plasma in Accelerating the Wound‐Healing Process and Recovery in Patients Being Operated for Pilonidal Sinus Disease: Preliminary Results
Authors: Spyridakis Michail , Christodoulidis Gregory , Chatzitheofilou Constantine , Symeonidis Dimitris , Tepetes Konstantinos
Published: May 2009

Background

Because of the poor quality of life that results from the open technique (open excision and packing) for surgically treating pilonidal cyst disease, several alternatives that accelerate the wound‐healing process have been proposed. This study aimed to evaluate the effect of platelet‐derived growth factors on the healing process.

Methods

Fifty‐two patients with pilonidal sinus disease who underwent open excision and secondary closure of the surgical wound (n = 22) or additional local postoperative infusion of platelet‐derived growth factors (n = 30) were evaluated. Duration of total wound healing and time to return to normal activities were evaluated. Quality of life of patients in each group was assessed via a stabilized questionnaire.

Results

Wound‐healing rates were much greater for the platelet group (p < 0.01). Complete healing of the surgical wound required 24 days for the platelet group while the respective time for the control group was more than 30 days (p < 0.01). Patients in the platelet group returned to their normal activities around the postoperative day 17 when mean wound volume was about 10 cc, while control group patients managed to do so around the postoperative day 25.

Conclusions

These data provide evidence that the use of platelet‐derived growth factors directly to the surgical wound enhances the healing process resulting in faster recovery of patients surgically treated for pilonidal sinus disease.
Impact of General Versus Local Anesthesia on Early Postoperative Cognitive Dysfunction Following Carotid Endarterectomy: GALA Study Subgroup Analysis
Authors: Weber Christian Friedrich , Friedl Hannah , Hueppe Michael , Hintereder Gudrun , Schmitz‐Rixen Thomas , Zwissler Bernhard , Meininger Dirk
Published: May 2009

Background

The aim of this study was to compare the influence of either general (GA) or local (LA) anesthesia on the postoperative neurocognitive outcome in patients undergoing carotid endarterectomy (CEA) in a randomized study. Therefore, we performed a subgroup analysis of the multicenter GALA study.

Methods

A total of 40 patients were enrolled and randomized to receive either LA (n = 17) or GA (n = 23) anesthesia. The indication for intraoperative shunting was based on the intraoperative cognitive performance in the LA group and on the clinical experience of the surgeon in the GA group. Outcome measurements included patient performance on a neuropsychological Trail Making Test, evaluation of patients mood using the self‐report inventory BSKE, and serum levels of the neurobiochemical marker S100ß. The data were analyzed for each variable using a t‐test and were presented as the mean (SD). Differences in shunt frequency were analyzed performing a chi‐squared test. Group differences in the Trail Making Test, BSKE evaluation, and S100ß concentrations were derived from the analyses of covariances with repeated measurements using preoperative values as covariates.

Results

Compared to baseline, the S100ß concentrations increased significantly in the GA group [0.086 (0.038) vs. 0.061 (0.024) μg/l; p < 0.001] before unclamping of the carotid artery, whereas there were no changes in the LA group [0.068 (0.024) μg/l, p = 0.09 vs. 0.061 (0.021) μg/l, p = 0.09). Furthermore, we detected significant group differences after surgical intervention (GA 0.087 (0.031) μg/l; LA 0.06 (0.021) μg/l; p = 0.006). The postoperative neurocognitive performance in the Trail Making Test decreased significantly in the GA group, whereas there were no significant changes in the LA group. The self‐report inventory BSKE evaluation revealed no significant group differences.

Conclusions

We concluded that performing local anesthesia in patients undergoing CEA positively influenced early postoperative neurocognitive outcomes. Significant group differences in postoperative S100ß concentrations confirmed the beneficial effect of local anesthesia.
Thymoma with Dissemination: Efficacy of Macroscopic Total Resection of Disseminated Nodules
Authors: Yano Motoki , Sasaki Hidefumi , Yukiue Haruhiro , Kawano Osamu , Okuda Katsuhiro , Hikosaka Yu , Fujii Yoshitaka
Published: May 2009

Background

Advanced thymomas with disseminated nodules are difficult to manage, and the treatment strategy remains undefined.

Methods

A total of 28 thymoma patients with pleural and/or pericardial disseminated nodules were treated at Nagoya City University Hospital. Among them, 21 patients underwent resection of thymoma and pleural disseminated nodules. These patients were reviewed in the present study.

Results

Preoperative steroid pulse therapy was performed in 14 patients. Macroscopic total resection of all tumors was achieved in 15 patients. Postoperative adjuvant radiotherapy was performed for the mediastinum in 20 patients and hemithoracic irradiation (HTR) in 11 patients. The overall survival rate of operated 21 patients was 73.1% at 5 years. The patients who underwent resection showed a better prognosis than the patients without resection (p = 0.0006). Relapse was diagnosed in 14 of 21 patients who underwent resection. Disease‐free survival was 67.5% at 1 year, 39.8% at 3 years, and 13.3% at 5 years. HTR alone did not improve the disease‐free survival. Among the patients who underwent total resection, relapse‐free survival was better than in the patients with subtotal resection (p = 0.009). Achievement of a trimodality therapy with preoperative steroid pulse, total resection, and postoperative HTR was associated with prolonged relapse‐free survival in the operated patients (p = 0.027, hazard ratio 6.452).

Conclusions

Pursuing total resection for thymoma and disseminated nodules may be beneficial for stage IV thymoma. The combination of preoperative steroid pulse therapy, macroscopic total resection, and postoperative HTR may prolong the interval to relapse, but it did not lead to cure.
Use of Ionic Liquid in Fabrication, Characterization, and Processing of Anodic Porous Alumina
Authors: Salerno Marco , Patra Niranjan , Cingolani Roberto
Published: May 2009

Two different ionic liquids have been tested in the electrochemical fabrication of anodic porous alumina in an aqueous solution of oxalic acid. It was found that during galvanostatic anodization of the aluminum at a current density of 200 mA/cm2, addition of 0.5% relative volume concentration of 1-butyl-3-methylimidazolium tetrafluoborate resulted in a three-fold increase of the growth rate, as compared to the bare acidic solution with the same acid concentration. This ionic liquid was also used successfully for an assessment of the wettability of the outer surface of the alumina, by means of liquid contact angle measurements. The results have been discussed and interpreted with the aid of atomic force microscopy. The observed wetting property allowed to use the ionic liquid for protection of the pores during a test removal of the oxide barrier layer.
Thermal tolerance and potential distribution of Carvalhotingis visenda (Hemiptera: Tingidae), a biological control agent for cat's claw creeper, Macfadyena unguis-cati (Bignoniaceae)
Authors: Dhileepan K. , Bayliss D. , Treviño M.
Published: May 2009

The specialist tingid, Carvalhotingis visenda, is a biological control agent for cat's claw creeper, Macfadyena unguis-cati (Bignoniaceae). Cat's claw creeper is an invasive liana with a wide climatic tolerance, and for biological control to be effective the tingid must survive and develop over a range of temperatures. We evaluated the effect of constant temperatures (0–45°C) on the survival and development of C. visenda. Adults showed tolerance for wider temperature ranges (0–45°C), but oviposition, egg hatching and nymphal development were all affected by both high (>30°C) and low (<20°C) temperatures. Temperatures between 20°C and 30°C are the most favourable for adult survival, oviposition, egg hatching and nymphal development. The ability of adults and nymphs to survive for a few days at high (40°C and 45°C) and low (0°C and 5°C) temperatures suggest that extreme temperature events, which usually occur for short durations (hours) in cat's claw creeper infested regions in Queensland and New South Wales states are not likely to affect the tingid population. The potential number of generations (egg to adult) the tingid can complete in a year in Australia ranged from three to eight, with more generations in Queensland than in New South Wales.