bluuebunny/crossref_metadata_2025 huggingface dataset:
The relationship between quality of life and swallowing in Parkinson's disease
Authors: Plowman‐Prine Emily K. , Sapienza Christine M. , Okun Michael S. , Pollock Stephenie L. , Jacobson Charles , Wu Sam S. , Rosenbek John C.
Published: May 2009

Few studies exist in the literature investigating the impact of idiopathic Parkinson's Disease (IPD) on swallow‐related quality of life. We therefore aimed in this project to: (1) evaluate swallow‐specific quality of life in IPD; (2) delineate potential relationships between IPD duration and severity with swallow‐specific quality of life; (3) investigate relationships between swallow‐specific quality of life and general health‐related quality of life; and (4) investigate relationships between swallow‐specific quality of life and depression. Thirty‐six patients diagnosed with IPD with and without dysphagia filled out self‐report assessments of the SWAL‐QOL, Parkinson's Disease Questionnaire‐39 (PDQ‐39), and Beck Depression Inventory (BDI). A series of Mann Whitney U tests were performed between non‐dysphagic and dysphagic groups for the total SWAL‐QOL score and the 10 SWAL‐QOL domains. Spearman's Rho correlation analyses were performed between the SWAL‐QOL and (1) PDQ‐39; (2) Hoehn and Yahr stage; (3) PD disease duration; (4) UPDRS “on” score; and (5) the BDI. The dysphagia swallowing group reported significant reductions compared to the non‐dysphagic group for the total SWAL‐QOL score (P = 0.02), mental health domain score (P = 0.002) and social domain score (P = 0.002). No relationships existed between swallow‐specific quality of life and disease duration or severity. Significant relationships existed between swallow‐specific quality of life and general health‐related quality of life (rs =−0.56, P = 0.000) and depression (rs = −0.48, P = 0.003). These exploratory data highlight the psychosocial sequelae that swallowing impairment can have in those with IPD and suggest a possible association between swallowing, social function, and depression. © 2009 Movement Disorder Society
Opinions and clinical practices related to diagnosing and managing patients with psychogenic movement disorders: An international survey of movement disorder society members
Authors: Espay Alberto J. , Goldenhar Linda M. , Voon Valerie , Schrag Anette , Burton Noël , Lang Anthony E.
Published: May 2009

Five hundred and nineteen members of the Movement Disorder Society completed a 22‐item questionnaire probing diagnostic and management issues in psychogenic movement disorders (PMD). When patients showed definite evidence of PMD with no other unexplained clinical features, approximately 20% said they informed patients of the diagnosis and requested no further neurological testing. The 51% who reported conducting standard neurological investigations to rule out organic causes before presenting the diagnosis to such patients had fewer years of fellowship training and fewer PMD patients seen per month. A non‐PMD diagnosis was correlated with patients' normal social or personal functioning, little or no employment disruption, lack of non‐physiologic findings, and lack of psychiatric history. Ongoing litigation was more predictive of the PMD diagnosis for US compared to non‐US respondents. Two thirds of respondents, more commonly younger and academic clinician researchers, refer PMD patients to a psychiatrist or mental health specialist while also providing personal follow up. Physician reimbursement, insurability of PMD patients, and ongoing litigation interfered with managing PMD patients to a greater extent in the US compared to non‐US countries. Acceptance of the diagnosis by the patient and identification and management of psychological stressors and concurrent psychiatric disorders were considered most important for predicting a favorable prognosis. These findings suggest that expert opinions and practices related to diagnosing and managing PMD patients differ among movement disorders neurologists. Some of the discrepancies may be accounted for by factors such as training, type of practice, volume of patients, and country of practice, but may also reflect absence of practice guidelines. © 2009 Movement Disorder Society
Reproductive factors, exogenous estrogen use, and risk of Parkinson's disease
Authors: Simon Kelly Claire , Chen Honglei , Gao Xiang , Schwarzschild Michael A. , Ascherio Alberto
Published: May 2009

To determine if reproductive factors or exogenous estrogen are associated with risk of Parkinson's disease (PD), we conducted a prospective study with 22 years of follow‐up among postmenopausal participants in the Nurses' Health Study. Relative risks (RRs) and 95% confidence intervals (CIs) of PD were estimated from a Cox proportional hazards model adjusting for potential confounders. Risk of PD was not significantly associated with any of the reproductive factors measured or exogenous estrogen use. Use of postmenopausal hormones, however, may modify the associations of smoking and caffeine intake with PD risk. The inverse relation between smoking and PD risk was attenuated among ever users of postmenopausal hormones (P for interaction = 0.05). Similar results were obtained for caffeine (P for interaction = 0.09). In exploratory analyses, women using progestin‐only hormones were found to have an increased PD risk, but this result was based on a very small number of cases (n = 4). In this large longitudinal study, we found no evidence of a beneficial effect of exogenous or endogenous estrogens on risk of PD. The use of postmenopausal hormone use may interact with other risk factors, but findings are preliminary and need confirmation in other populations. © 2009 Movement Disorder Society
Determinants of sleep problems in patients with spondyloarthropathy
Authors: Da Costa Deborah , Zummer Michel , Fitzcharles Mary‐Ann
Published: May 2009

Objective: To characterize sleep complaints and identify biopsychosocial factors associated with sleep problems in patients with spondyloarthropathy (SpA).

Methods: The sample comprised 125 patients with SpA. Sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI). Participants completed standardized questionnaires assessing depressed mood, perceived stress, leisure time physical activity, functional disability and disease activity. A series of hierarchical multiple regressions were computed to examine the determinants of the following sleep parameters: quality, latency, duration and efficiency.

Results: The mean global PSQI score was 8.7 (SD = 5.0), with 69% of the sample classified as poor sleepers (PSQI global score >5). Worse functional status was associated with poorer sleep quality (p = 0.006), longer sleep latency (p = 0.004), shorter sleep duration (p = 0.001) and poorer sleep efficiency (p = 0.004). Higher depressed mood scores emerged in the multivariate analyses as a significant determinant of poorer sleep quality (p = 0.010), shorter sleep duration (p = 0.007) and poorer sleep efficiency (p = 0.006). Higher perceived stress was an independent contributor of poorer sleep quality (p = 0.033). The relationships between worse functional status and poorer sleep quality and shorter sleep duration were more pronounced for participants who completed the questionnaires in the English language.

Conclusions: Sleep problems are prevalent among patients with SpA. Our findings suggest that multiple factors are associated with sleep complaints in persons with SpA with functional status, depressed mood and stress differentially contributing to specific sleep parameters. Multimodal interventions, which include non‐pharmacological methods targeting these biopsychosocial factors, require evaluation to optimize the management of sleep disruptions in SpA. Copyright © 2009 John Wiley & Sons, Ltd.
Smooth, second order, non‐negative meshfree approximants selected by maximum entropy
Authors: Cyron C. J. , Arroyo M. , Ortiz M.
Published: May 2009

We present a family of approximation schemes, which we refer to as second‐order maximum‐entropy (max‐ent) approximation schemes, that extends the first‐order local max‐ent approximation schemes to second‐order consistency. This method retains the fundamental properties of first‐order max‐ent schemes, namely the shape functions are smooth, non‐negative, and satisfy a weak Kronecker‐delta property at the boundary. This last property makes the imposition of essential boundary conditions in the numerical solution of partial differential equations trivial. The evaluation of the shape functions is not explicit, but it is very efficient and robust. To our knowledge, the proposed method is the first higher‐order scheme for function approximation from unstructured data in arbitrary dimensions with non‐negative shape functions. As a consequence, the approximants exhibit variation diminishing properties, as well as an excellent behavior in structural vibrations problems as compared with the Lagrange finite elements, MLS‐based meshfree methods and even B‐Spline approximations, as shown through numerical experiments. When compared with usual MLS‐based second‐order meshfree methods, the shape functions presented here are much easier to integrate in a Galerkin approach, as illustrated by the standard benchmark problems. Copyright © 2009 John Wiley & Sons, Ltd.
Improved stability and stabilization approach to linear interconnected time‐delay systems
Authors: Mahmoud Magdi S.
Published: May 2009

In this paper, we investigate the problems of delay‐dependent analysis and state‐feedback synthesis for a class of linear continuous‐time interconnected systems with time‐varying delays. An augmented Lyapunov functional is properly constructed for the individual subsystems and an improved free‐weighting method is deployed to exhibit the delay‐dependent dynamics. Delay‐dependent stability analysis is then performed to develop linear matrix inequalities (LMIs)‐based conditions under which the family of linear delay subsystems is asymptotically stable with a γ‐level ℒ︁2‐gain for the nominal model. Extension to systems with convex bounded parameter uncertainties in all system matrices is also provided. All the required numerical computations are performed on the subsystem level. By delay‐dependent stabilization, we design a family of local state‐feedback schemes to guarantee that the closed‐loop subsystem enjoys the delay‐dependent asymptotic stability with a prescribed γ‐level ℒ︁2‐gain. The developed results are tested on a representative example to illustrate the theoretical developments. Copyright © 2009 John Wiley & Sons, Ltd.
Contemporary Knowledge and Skill Requirements in Project Management
Authors: Ingason Helgi Thor , Jónasson Haukur Ingi
Published: May 2009

This article provides an overview of some recent developments within the field of project management and presents metrics used to assess current trends within the discipline in order to identify its future direction. Graphical tools are introduced to measure the span and areas of emphasis within project management, such as radar diagrams and the recently introduced International Project Management Association (IPMA) “Eye of Competence.” The research shows that the discipline seems to focus increasingly on interpersonal competences, relationship management, resource management, and strategic alignment. The results are evaluated and discussed, and the article concludes with some ideas about the future development of project management.
Identification of a human estrogen receptor α‐derived antiestrogenic peptide that adopts a polyproline II conformation
Authors: Kapitán Josef , Gallo Dominique , Goasdoué Nicole , Nicaise Magali , Desmadril Michel , Hecht Lutz , Leclercq Guy , Barron Laurence D. , Jacquot Yves
Published: May 2009

Polyproline II (PPII) helix is an extended secondary structure present in a number of proteins. PPII‐containing sequences mediate specific protein–protein interactions with partners containing appropriate cognate domains called PPII‐recognizing domains (PRDs) and are involved in the activation of intracellular signaling pathways. Thus, the identification of PPII structures in proteins is of great interest, not only to explore molecular and physiological mechanisms, but also to elaborate new potential drugs. By revisiting X‐ray crystal structures of liganded α‐type human estrogen receptor (ERα), we have identified an 11‐residue PPII‐helical sequence (D321AEPPILYSEY331) in the ligand‐binding domain of the receptor. The data recorded by far‐ultraviolet circular dichroism (far‐UV CD), vibrational Raman optical activity (ROA) and differential scanning calorimetry (DSC) show that the corresponding peptide (Ac‐DAEPPILYSEY‐NH2) is particularly well structured in PPII, with the same proportion of PPII as observed from X‐ray structures (∼85%). In addition, studies carried out on ERα‐negative Evsa‐T breast cancer cells transiently co‐transfected with a pcDNA3‐ERα plasmid and a Vit‐tk‐Luc reporter gene revealed that the peptide antagonizes the estradiol‐induced transcription providing perspectives for researching new molecules with antagonistic properties. Copyright © 2009 European Peptide Society and John Wiley & Sons, Ltd.
Differential population development in the regions of Finland
Authors: Heikkilä Elli , Pikkarainen Maria
Published: May 2009

This paper considers regional population development in Finland. The paper focuses in particular on the role of inter‐regional migration in reshaping the regional population distribution, and suggests that this has contributed to regional development inequalities. The paper questions whether policies to counter this trend following a Floridian approach can ever be effective. Copyright © 2009 John Wiley & Sons, Ltd.
Structure and transition of charged excitons
Authors: Ge Li , George Thomas F. , Sun Xin
Published: May 2009

In a polymer, a positive polaron p+ attracts a negative polaron p– to form an exciton, which is neutral and has spin s = 0 (singlet, emissive) or s = 1 (triplet, non‐emissive). However, in non‐degenerate polymers, bipolarons (B) which are doubly charged and spinless are also carriers, such that B2+ (B2–) attracts p– (p+) to form a new kind of exciton – the charged exciton. Since the charged exciton has spin s = 1/2, the triplet state does not appear and is emissive. The structure and transition probability of the charged exciton are presented in this paper. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Low dimensional nanostructured InGaN multi‐quantum wells by selective area heteroepitaxy
Authors: Keyan Zang , Yadong Wang , Jin Chua Soo
Published: May 2009

InGaN/GaN multiple quantum wells (MQWs) nanostructures were demonstrated on high density GaN nanorod arrays with controllable size by using template‐assisted selective area heteroepitaxial growth. The nanostructures with average diameter of ∼60 nm were selectively grown by metalorganic chemical vapor deposition (MOCVD) on a nano‐patterned SiO2/GaN template. The nanoporous SiO2 on GaN surface was created by inductively coupled plasma etching (ICP) using anodic aluminium oxide (AAO) template as an etching mask. The nanostructured InGaN MQWs demonstrates low defect density, confirmed by high resolution transmission electron microscopy. More importantly, InGaN MQWs nanostructures demonstrate a higher photoluminescence in intensity, compared to that of a planar GaN. This is contributed to the improvement of light extraction due to the faceted nanostructures and the improvement in crystal quality. In addition, more Indium incorporation has been demonstrated compared to the control InGaN MQWs due to strain‐relaxation in GaN nanorods. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Enhanced device performance of GaInN‐based deep green light emitting diodes with V‐defect‐free active region
Authors: Detchprohm T. , Zhu M. , Zhao W. , Wang Y. , Li Y. , Xia Y. , Wetzel C.
Published: May 2009

We have performed the epitaxial growth of GaInN based deep green (540–570 nm) light emitting diodes (LEDs) by introducing processes to avoid the formation of V‐defects in the active region of the GaInN/GaN multiple quantum wells. For 541 and 559 nm LED wafers, the light output power (LOP) at 90 A/cm2 reaches as high as 14 and 8 mW, respectively. These values are 4 times larger than those of typical deep green LED wafers with average V‐defect density of 2–5 × 108cm–2. Under pulsed operation (pulse width of 50 μs, duty cycle 1%), the external quantum efficiency exhibits a maximum of 39% at 16 A/cm2 in 558 nm LED die of size (350 μm)2. This type of V‐defect‐free LED die also shows excellent lifetime behaviour. In 168 hr stress test of 30 mA at 80 °C, LOP declines less than 5%. Apparently, eliminating V‐defects from the active region significantly enhances the reliability of deep green LEDs. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ab initio calculation for an initial growth process of GaN on (0001) and (000$ \bar 1 $) surfaces by vapor phase epitaxy
Authors: Suzuki Hikari , Togashi Rie , Murakami Hisashi , Kumagai Yoshinao , Koukitu Akinori
Published: May 2009

The adsorption processes of group‐III and group‐V sources used in metalorganic vapor phase epitaxy (MOVPE) and hydride vapor phase epitaxy (HVPE) were investigated using ab initio calculations based on the density functional theory (DFT) to understand the initial growth process of GaN on GaN(0001) and (000$ \bar 1 $) substrates. In order to understand the influence from the decomposition of ammonia, NH2, NH and N were considered as adsorption species. We assume group‐V source preflow in the case of GaN(0001) and group‐III preflow in the case of GaN(000$ \bar 1 $). From the calculations, the initial GaN growth process in the vapor phase epitaxy is clarified. When GaN is grown on the GaN(0001) substrate, NH3 molecules adsorb to the on‐top site or NH2 molecules adsorb to the bridge site. Also, it was found that the surface structures with both NH2 and NH3 are stable under a hydrogen atmosphere. When GaN is grown on the GaN(000$ \bar 1 $) substrate, Ga atoms adsorb to the H3 site in the case of MOVPE and GaCl molecules adsorb to the H3 site with the Ga atom facing the surface in the case of HVPE. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Anomalous time variation of photocurrent in GaN during photoelectrochemical reaction for H2 gas generation in NaOH aqueous solution
Authors: Sato Keiichi , Fujii Katsushi , Koike Kayo , Goto Takenari , Yao Takafumi
Published: May 2009

We investigated the time variation of photocurrent in GaN during photoelectrochemical reaction without bias. The time variation of photocurrent showed a “w”‐shape behaviour. The surface morphology and photoluminescence spectra of GaN after the reaction with different treatment times were also evaluated in order to clarify the “w”‐shape time variation. The roughened and chemically changed surface of the GaN caused the “w”‐shape time variation. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Photon‐assisted tunneling in GaN nanowire white light emitting diodes
Authors: Yeh P.‐C. , Hwa M.‐C. , Yu J.‐W. , Wu H.‐M. , Tsai H.‐L. , Lai C.‐M. , Huang J.‐J. , Yang J.‐R. , Peng L.‐H.
Published: May 2009

We reported intensive greenish white light electroluminescence, accompanied with 364 nm bandedge emission from GaN nanowires/p‐GaN light emitting diode operated in the high‐field forward bias regime. Strong bandedge emission, dominant over visible luminescence from bandgap state transitions, was also observed in the reverse bias regime. These observations were ascribed to a formation of n+‐p tunnel junction in the high‐field regime and emission mechanism due to photon‐assisted tunneling process. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Controlled formation of voids at the AlN/sapphire interface by sapphire decomposition for self‐separation of the AlN layer
Authors: Tajima J. , Kubota Y. , Ishizuki M. , Nagashima T. , Togashi R. , Murakami H. , Kumagai Y. , Takada K. , Koukitu A.
Published: May 2009

Self‐separation of hydride vapor phase epitaxy (HVPE)‐grown AlN layer from sapphire substrate was achieved by the formation of voids at the AlN/sapphire interface. Voids could be formed through the decomposition of sapphire beneath a thin (100 nm) protective AlN layer grown at 1065 °C by heating at 1450 °C in a carrier gas (H2 + N2) containing NH3. Additionally, the void size could be controlled by varying the heating time. As the results of controlled formation of voids, after growth of a thick (85 μm) AlN layer on the thin protective AlN layer heated at 1450 °C for 30 min, self‐separation of the AlN layer from a sapphire substrate occurred by the compressive stress from difference in thermal expansion coefficients between AlN and sapphire during post‐growth cooling. The self‐separated thick AlN layer had low concentration of impurities, and showed clear photoluminescence peak at 208.4 nm. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
I‐V and C‐V characteristics of rare‐earth‐metal/p‐GaN Schottky contacts
Authors: Fukushima Yoshihiro , Ogisu Keita , Kuzuhara Masaaki , Shiojima Kenji
Published: May 2009

The electrical properties of rare‐earth‐metal Schottky contacts to p‐GaN were characterized with current‐voltage (I‐V) and capacitance‐voltage (C‐V) measurements for the first time. Three kinds of rare‐earth‐metal films of Dy, Er, and Gd, which have low‐metal‐work‐function nature, were deposited on low‐Mg‐doped p‐GaN. Linear regions of more than one and a half orders were seen in a forward semi‐log I‐V plot, and reverse break down voltages were as high as around 60 V for all samples. In the C‐V characteristics, good linearity was obtained in a 1/C2 plot for all samples. The carrier concentration was estimated to be about 5.5×1016 cm–3, which is a reasonable value of activation efficiency of 4.2%. The Schottky barrier heights of Dy, Er, and Gd contacts were 1.91, 2.38, and 2.16 eV from I‐V, and 1.79, 1.78, and 1.70 eV from C‐V, respectively. These values are as high as those of the transition metal contacts. These results tell us that Fermi level pinning is significantly strong for p‐GaN surfaces with a conventional acid treatment. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High‐power GaN‐HEMT with high three‐terminal breakdown voltage for W‐band applications
Authors: Makiyama Kozo , Ohki Toshihiro , Kanamura Masahito , Joshin Kazukiyo , Imanishi Kenji , Hara Naoki , Kikkawa Toshihide
Published: May 2009

In this paper, we reported on a technology to improve the three‐terminal breakdown voltage of a GaN high electron mobility transistor (GaN‐HEMT) for a millimetre‐wave amplifier. To fabricate high‐power and high‐efficiency GaN‐HEMT millimetre‐wave amplifier, it is necessary to improve the three‐terminal breakdown voltage and the pinched‐off current. In this work, the thickness of the GaN channel layer and the quality of the channel layer has been improved by adding small quantities of Al to the GaN buffer. We demonstrated a high maximum frequency of oscillation (fmax) of over 200 GHz with a pinched‐off current of 10–6 A/mm at Vds of 50 V for a device with a gate length of 100 nm. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The effect of absorption layer of different quantum well arrangement on optoelectronic characteristics of nitride‐based photovoltaic cells grown by MOCVD
Authors: Fu Y. K. , Tun C. J. , Kuo C. W. , Kuo C. H. , Pan C. J. , Chi G. C. , Chen M. C. , Hong H. F. , Lan S. M.
Published: May 2009

In this study, III‐nitride solar cells with multi‐quantum well (MQW) absorption layer were grown on sapphire substrates by metal organic chemical vapor deposition (MOCVD). The effect of different quantum well (QW) arrangement on optoelectronic characteristics of III‐nitrides photovoltaic cells was investigated. It was found that the upper quantum well (QW) layer will dominate electroluminescence (EL) emission mechanism and the electrical characteristics of solar cell.

The advantage of modulating the short‐circuit current density (JSC) and open‐circuit voltage (VOC) can be obtained by different arrangement of blue and green QW in MQW absorption layer. The optimum electrical characteristics of solar cell with a JSC of 0.30 mA/cm2, a VOC up to 1.51 V, fill factor (FF) as high as 0.601, and a series resistance (RS) of 9 Ω can be obtained by using MQW absorption layer. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Improvement of crystal quality of GaN grown on AlN template by MOCVD using HT‐AlN interlayer
Authors: Yuebin Tao , Zhizhong Chen , Zhijian Yang , Liwen Sang , Zhitao Chen , Ding Li , Hao Fang , Yaobo Pan , Jianfeng Yan , Guangmin Zhu , Cheng Chen , Shitao Li , Maosheng Hao , Guoyi Zhang
Published: May 2009

Two GaN samples, with and without high temperature (HT)‐AlN interlayer (labelled as sample A and B, respectively) grown by MOCVD on AlN template, were investigated by double‐crystal X‐ray diffraction (DC‐XRD), photoluminescence (PL), and atomic force microscope (AFM) measurements. It was found that the crystal quality of GaN could be greatly improved by the HT‐AlN interlayer. The full width at half maximum (FWHM) of (102) reflection in XRD rocking curve was narrower for sample A than that for sample B. However, the FWHMs of (002) reflections were almost the same for the two samples. In addition, the tilt degree which reflected screw dislocation density was almost the same, while the twist degree which reflected edge dislocation density changed from 0.214° to 0.152° when the HT‐AlN interlayer was used. Both the intensities of (102) reflection in XRD and band edge emission in PL for sample A were stronger too. In the AFM images, the atomic growth steps of sample A were clearer than those of sample B. According to the results of the in situ optical reflectivity spectra and the atomic force microscope (AFM) images, the above results were attributed to the three‐dimensional (3D) growth mode of the HT‐AlN interlayer. The HT‐AlN interlayer may work as a kind of “micro‐area” seed for epitaxial lateral overgrowth (ELOG) resulting in bending some dislocations. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Determination of the thermo‐optic coefficients of GaN and AlN up to 515 °C
Authors: Watanabe Naoki , Kimoto Tsunenobu , Suda Jun
Published: May 2009

The refractive index dispersions of hexagonal GaN and AlN have been investigated to determine the thermo‐optic coefficients. Measurements were conducted at temperatures ranging from room temperature up to 515 °C in the wavelength range from the near band‐edge to 1000 nm. Optical interference measurements with vertical incident configuration were employed to precisely evaluate the ordinary refractive indices. Optical simulation of AlGaN/GaN distributed Bragg reflectors was also carried out by using the obtained thermo‐optic coefficients. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the origin of IQE‐‘droop’ in InGaN LEDs
Authors: Laubsch Ansgar , Sabathil Matthias , Bergbauer Werner , Strassburg Martin , Lugauer Hans , Peter Matthias , Lutgen Stephan , Linder Norbert , Streubel Klaus , Hader Jörg , Moloney Jerome V. , Pasenow Bernhard , Koch Stephan W.
Published: May 2009

We identify a quantum well internal high density Augerlike loss process as the origin of the so called ‘droop’ of internal quantum efficiency (IQE) in InGaN based light emitters. The IQE of such a device peaks at small current densities and then monotonously decreases towards higher currents. The origin of this ‘droop’ has been widely discussed recently and many possible mechanisms have been proposed for explaining the effect. We compare temperature and carrier density dependent electroluminescence and photoluminescence measurements of a green emitting single quantum‐well (SQW) LED over a wide parameter range. The carrier‐density as well as temperature dependence of efficiency is identical in both measurements, indicating that the decrease is due to a high density quantum‐well internal loss process. The data can be accurately modeled assuming an Auger‐like loss process with C = 3.5 × 10–31 cm6s–1. We suggest phonon‐ or defect‐assisted Auger recombination as the origin of this loss‐channel. The high current performance can be improved if a thick InGaN SQW or a multi quantum‐well (MQW) is used. This is in very good agreement with theoretical simulations (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mechanism of thermal degradation in GaInN/GaN quantum wells
Authors: Bremers H. , Jönen H. , Hoffmann L. , Rossow U. , Hangleiter A.
Published: May 2009

In this contribution we focus on degradation processes of GaInN multiple quantum wells (MQWs) used in laser structures grown by metallorganic vapor pressure epitaxy (MOVPE). The influence of ramp‐up time as well as the maximum temperature during growth of the barrier on the quantum well (QW) is investigated. Comparison of X‐ray and photoluminescence (PL) measurements implies that a sufficient thickness of a cover layer grown at low temperature is required to prevent degradation of the QW.

In a next step samples were grown using an optimal thermal budget during growth of the active region to investigate the influence of capping layers. To improve crystalline quality of these layers high temperatures are required. Our measurements show that these high temperatures lead to a decrease in average indium concentration of the QWs. This decrease is temperature as well as time dependent (∝ √t) and can only explained by diffusion processes. The activation energies are in the range 0.7‐0.9 eV (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Non‐Gaussian conductance noise in disordered electronic systems [Phys. Status Solidi C 5, No. 3, 809–813 (2008)]
Authors: Orlyanchik V. , Kozub V. I. , Ovadyahu Z.
Published: May 2009

The abstract of the paper contained an error. The corrected abstract is given below. Note that the only change is in the last sentence which has to be read: “It is concluded that the non‐Gaussian features can be observed whether or not the system is glassy.” (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A new generalization of Weibull distribution with application to a breast cancer data set
Authors: Wahed Abdus S. , Luong The Minh , Jeong Jong‐Hyeon
Published: May 2009

In this article, we propose a new generalization of the Weibull distribution, which incorporates the exponentiated Weibull distribution introduced by Mudholkar and Srivastava (IEEE Trans. Reliab. 1993; 42:299–302) as a special case. We refer to the new family of distributions as the beta‐Weibull distribution. We investigate the potential usefulness of the beta‐Weibull distribution for modeling censored survival data from biomedical studies. Several other generalizations of the standard two‐parameter Weibull distribution are compared with regards to maximum likelihood inference of the cumulative incidence function, under the setting of competing risks. These Weibull‐based parametric models are fit to a breast cancer data set from the National Surgical Adjuvant Breast and Bowel Project. In terms of statistical significance of the treatment effect and model adequacy, all generalized models lead to similar conclusions, suggesting that the beta‐Weibull family is a reasonable candidate for modeling survival data. Copyright © 2009 John Wiley & Sons, Ltd.
A selection model for longitudinal binary responses subject to non‐ignorable attrition
Authors: Alfò Marco , Maruotti Antonello
Published: May 2009

Longitudinal studies collect information on a sample of individuals which is followed over time to analyze the effects of individual and time‐dependent characteristics on the observed response. These studies often suffer fromattrition: individuals drop out of the study before its completion time and thus present incomplete data records. When the missing mechanism, once conditioned on other (observed) variables, does not depend on current (eventually unobserved) values of the response variable, the dropout mechanism is known to be ignorable. We propose a selection model extending semiparametric variance component models for longitudinal binary responses to allow for dependence between the missing data mechanism and the primary response process. The model is applied to a data set from a methadone maintenance treatment programme held in Sidney, 1986. Copyright © 2009 John Wiley & Sons, Ltd.
A customizable pattern‐based software process simulation model: design, calibration and application
Authors: Garousi Vahid , Khosrovian Keyvan , Pfahl Dietmar
Published: May 2009

Software process analysis and improvement relies heavily on empirical research. Empirical research requires measurement, experimentation, and modeling. However, whatever evidence is gained via empirical research is strongly context dependent. Thus, it is hard to combine results and capitalize upon them for the purpose of improvement in evolving development environments. The process simulation model GENSIM 2.0 addresses these challenges. GENSIM 2.0 is a generic process simulation tool representing V‐model type software development processes. Compared to existing process simulation models in the literature, the novelty of GENSIM 2.0 is twofold. Firstly, its model structure is customizable to organization‐specific processes. This is achieved by using a limited set of generic structures (macro‐patterns). Secondly, its model parameters can be easily calibrated to available empirical data and expert knowledge. This is achieved by making the internal model structures explicit and by providing guidance on how to calibrate model parameters. This article outlines the structure of GENSIM 2.0, gives examples on how to calibrate the model to available empirical data, and demonstrates its usefulness through two application scenarios The first scenario illustrates how GENSIM 2.0 helps in finding effective combinations of verification and validation techniques under given time and effort constraints. The second scenario shows how the simulator supports in finding the best combination of alternative verification techniques. Copyright © 2009 John Wiley & Sons, Ltd.
Antimalarial natural products of marine and freshwater origin
Authors: Gademann Karl , Kobylinska Joanna
Published: May 2009

This review highlights recently discovered antimalarial natural products from marine and freshwater sources described in the literature from 2006 to 2008. The structures as well as bioactivities of compounds against the malaria parasites such asPlasmodium falciparumare discussed, including, for example, agelasine, xestoquinone, alisiaquinone, crambescidin, venturamide, dragomabin, gragonamide, viridamide, salinosporamide, chaetoxanthone, nodulisporacid, tumonoic acid, girolline, oroidin, nostocarboline, aerucyclamide, and microcylamide 7806 and its revised structure. Synthetic derivatives of natural products are presented including plakortin, isoaaptamine, curcuphenol, pseudopyronine, manzamine, and nostocarboline. Consequences of these discoveries for the development of novel natural product agents against malaria are discussed. © 2009 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 9: 187–198; 2009: Published online in Wiley InterScience (www.interscience.wiley.com)DOI 10.1002/tcr.200900001
Operative Debridement of Pressure Ulcers
Authors: Schiffman Jessica , Golinko Michael S. , Yan Alan , Flattau Anna , Tomic‐Canic Marjana , Brem Harold
Published: May 2009

Background

Infection in severe pressure ulcers can lead to sepsis with a 6‐month mortality as high as 68%.

Methods

Operative records of 142 consecutive operative debridements on 60 patients in a dedicated wound healing inpatient unit were reviewed, from the Wound Electronic Medical Record, for identification of key steps in debridement technique, mortality, unexpected returns, and time to discharge following debridement.

Results

The mean age of the patients was 73.1 years, and 45% were men. Most wounds (53%) were located on the hip (ischial or trochanteric); others were on the sacrum (32%) and the heels (14%). The mean initial wound area prior to debridement was 14.0 cm2, and 83% of debridements were performed on stage IV pressure ulcers. The postoperative hospital stay averaged 4.1 days. Key steps in the technique included (1) exposure of areas of undermining by excising overlying tissue; (2) removal of callus from wound edges; (3) removal of all grossly infected tissue; and (4) obtaining a biopsy of the deep tissue after debridement of all nonviable or infected tissue for culture and pathology to determine the presence of infection, fibrosis, and granulation tissue. There was one death 9 days post‐debridement of a sacral ulcer and one unplanned return to the operating room for bleeding 8 days post‐debridement.

Conclusions

Operative debridement of pressure ulcers is safe, despite the medical co‐morbidities in patients with severe pressure ulcers. Proper debridement technique may prevent sepsis and death in patients with multiple co‐morbid conditions.
Is the Retrojugular Approach Safer Than the Conventional Approach for Carotid Endarterectomy?
Authors: Kluk J. , Grainger S. , Nyamekye I. K.
Published: May 2009

Background

The retrojugular approach is promoted as an alternative to traditional antejugular carotid endarterectomy. Absence of named posterior venous branches and ease of distal internal carotid dissection reduce time for carotid exposure together with improved distal exposure. However, a higher incidence of local nerve injury and persistent hoarse voice has been reported. We compare the incidence of these and other complications for the antejugular and retrojugular approaches.

Design

This is a nonrandomised retrospective review of prospectively collected data on consecutive patients undergoing carotid endarterectomy.

Results

Our 178 patients formed two groups who were homogeneous in terms of sex and age. Mean operative times, patch usage, and general/local anaesthesia did not differ significantly for the two groups. Postoperative complications including transient ischemic attack (TIA), major stroke, or death; hypertension; miosis; and hypoglossal injury were similar for the two groups. However, there was a significantly increased incidence of persistent hoarse voice (p < 0.05) in the retrojugular group.

Conclusions

Reports of increased incidence of persistent hoarse voice associated with the retrojugular approach to carotid endarterectomy are supported by our findings, which point to a learning curve effect. A randomized controlled trial would be necessary before any strong recommendation could be made for or against the retrojugular approach.
Surgical Management of Giant Liver Tumor Involving the Hepatic Hilum of Children
Authors: Dong Qian , Jiang Buxian , Lu Yun , Zhang Hong , Jiang Zhong , Lu Hongting , Yang Chuanmin , Zhao Jing , Hao Xiwei
Published: May 2009

Background

Surgical management of giant liver tumors involving the hepatic hilum tends to be very difficult. The present study assessed the feasibility and safety of resection of such liver tumors.

Methods

We evaluated 27 patients with liver tumors involving the hepatic hilum. The patients ranged in age from 3 months to 14 years (mean, 4.2 years). Of the 27 cases, 23 were resected completely during the past 10 years. The other four cases did not undergo operation because of their parents’ decisions to discontinue treatment; these cases had multiple space‐occupying lesions in addition to tumors involving the hepatic hilum. Before resection, the tumor was fully exposed and an occluding tape was placed around the vena cava when necessary.

Results

The hepatectomies were performed under intermittent portal triad clamping; 23 cases were successfully resected without postoperative mortality or morbidity. The mean operation duration was 205 min and mean blood loss was 120 ml. Pathological diagnoses included hepatoblastoma (n = 9), endotheliosarcoma (n = 1), mesenchymal hamartoma (n = 4), teratoma (n = 1), adenoma (n = 3), and hepatocellular carcinoma (n = 4). The nine cases with benign liver tumors were healthy at follow‐up at 11 months to 9 years after operation. Of the 14 cases with malignant tumors, six died from recurrence, metastasis, or other complications. The other eight cases were still alive without clinical tumors.

Conclusions

Resecting giant liver tumors involving the main hepatic veins and/or the retrohepatic vena cava, although challenging, is feasible and safe.
Use of India Ink During Preoperative Computed Tomography Localization of Small Peripheral Undiagnosed Pulmonary Nodules for Thoracoscopic Resection
Authors: Magistrelli Prospero , D’Ambra Luigi , Berti Stefano , Feleppa Cosimo , Stefanini Teseo , Falco Emilio
Published: May 2009

Background

Computed tomography (CT) scans of the chest permit us to identify a large number of small peripheral, undefined pulmonary lesions that require a diagnosis. Broncoscopy results are generally negative in these cases, and needle aspiration results are often inconclusive owing to poor cytology and false‐negative cases. Thoracoscopy is an ideal tool but allows us only to localize lesions that retract the visceral pleura. Our aim in this study was to establish a marking procedure for excising nodules of unknown etiology by injecting India ink on the surface of the lung.

Methods

Since January 2008, eight patients (six men, two women) who had been diagnosed as having a peripheral small pulmonary nodule of unknown etiology were selected for preoperative tattooing under CT guidance to facilitate thoracoscopic wedge resection.

Results

In six cases, thoracoscopy allowed diagnosis and definitive treatment of two benign peripheral nodules and four single metastases from colon carcinoma. In two patients who had been diagnosed to have a primitive non‐small‐cell lung cancer on frozen section following thoracoscopy, the surgical treatment was concluded with limited lateral thoracotomy and lobectomy with ilomediastinal node dissection.

Conclusions

Our experience suggests that this CT technique, which includes using India ink to label and localize peripheral small pulmonary nodules, is a safe, valid option for marking the lung, thereby facilitating subsequent thoracoscopic resection.
Systematic Review and Pooled Estimates for the Diagnostic Accuracy of Serological Markers for Intestinal Ischemia
Authors: Evennett Nicholas J. , Petrov Maxim S. , Mittal Anubhav , Windsor John A.
Published: May 2009

Background

Intestinal ischemia is a potentially catastrophic abdominal emergency that presents a significant diagnostic challenge in the critical care setting. We performed a systematic review of the literature to define the diagnostic accuracy of serological markers of intestinal ischemia.

Methods

Observational studies on the performance of markers of intestinal ischemia were identified within the MEDLINE and EMBASE electronic databases. All studies from which it was possible to derive true positive, false positive, false negative, and true negative results were included. A random‐effects model was used to calculate the pooled estimates of diagnostic accuracy.

Results

A total of 20 articles examining 18 different serological markers were identified that met the inclusion criteria. The global measures of test performance (diagnostic odds ratio and area under the summary receiver operating characteristic curve) for markers investigated in three or more studies were d‐lactate (10.75 and 0.86, respectively), glutathione S‐transferase (GST; 8.82 and 0.87, respectively), intestinal fatty‐acid binding protein (i‐FABP; 7.62 and 0.78, respectively), and d‐dimer (5.77 and 0.53, respectively).

Conclusions

The performance of the currently available serological markers is suboptimal for routine clinical use, but novel markers of intestinal ischemia such as d‐lactate, GST, and i‐FABP may offer improved diagnostic accuracy. The early diagnosis of intestinal ischemia remains a challenge, and further research is required to identify improved serological markers and to demonstrate their clinical utility in the individual patient.
Angioleiomyoma of Distal Ulnar Artery of the Hand
Authors: Shafi Mohamed , Hattori Yasunori , Doi Kazuteru
Published: May 2009

Angioleiomyomas are rare and benign smooth muscle tumors that are infrequently found in the hand. We present a case of angioleiomyoma of the distal ulnar artery that presented with painless mass and gradual enlargement. 3D computed tomography angiography revealed a mass involved with ulnar artery. Surgical excision was performed, and the histology was characteristic of an angioleiomyoma. The patient became asymptomatic after the operation. At 1-year follow-up after the operation, no recurrence has developed. The purpose of this case report is, furthermore, to consider the differential diagnosis in painless masses of the hand.
Assessment of the In Vivo Toxicity of Gold Nanoparticles
Authors: Chen Yu-Shiun , Hung Yao-Ching , Liau Ian , Huang G Steve
Published: May 2009

The environmental impact of nanoparticles is evident; however, their toxicity due to their nanosize is rarely discussed. Gold nanoparticles (GNPs) may serve as a promising model to address the size-dependent biological response to nanoparticles because they show good biocompatibility and their size can be controlled with great precision during their chemical synthesis. Naked GNPs ranging from 3 to 100 nm were injected intraperitoneally into BALB/C mice at a dose of 8 mg/kg/week. GNPs of 3, 5, 50, and 100 nm did not show harmful effects; however, GNPs ranging from 8 to 37 nm induced severe sickness in mice. Mice injected with GNPs in this range showed fatigue, loss of appetite, change of fur color, and weight loss. Starting from day 14, mice in this group exhibited a camel-like back and crooked spine. The majority of mice in these groups died within 21 days. Injection of 5 and 3 nm GNPs, however, did not induce sickness or lethality in mice. Pathological examination of the major organs of the mice in the diseased groups indicated an increase of Kupffer cells in the liver, loss of structural integrity in the lungs, and diffusion of white pulp in the spleen. The pathological abnormality was associated with the presence of gold particles at the diseased sites, which were verified by ex vivo Coherent anti-Stoke Raman scattering microscopy. Modifying the surface of the GNPs by incorporating immunogenic peptides ameliorated their toxicity. This reduction in the toxicity is associated with an increase in the ability to induce antibody response. The toxicity of GNPs may be a fundamental determinant of the environmental toxicity of nanoparticles.
Symposium 9: Competent to care Are all doctors competent in nutrition?
Authors: Leslie Fiona C. , Thomas Suraj
Published: May 2009

Optimising nutrition is known to improve outcome in a variety of specialities from elderly care to orthopaedics. The National Institute for Health and Clinical Excellence guidelines of 2006 have provided standards to positively influence the profile of nutrition within the National Health Service. However, what role do doctors have in this process? Clearly, not all doctors are competent in nutrition. In a recent US survey only 14% of resident physicians reported feeling adequately trained to provide nutrition counselling. A lack of knowledge has also been demonstrated by general practitioners (GP). The Intercollegiate Group on Nutrition is working to improve nutritional knowledge in British medical graduates. In addition, nutritional care is now a core competency assessed in the UK Foundation Programme curriculum, which can only be a positive step. The assessment process may even influence some of the supervising consultants. What about those doctors currently practising in the UK? Recently, a questionnaire study was undertaken to look at healthcare professionals' knowledge of the benefits and risks of percutaneous endoscopic gastrostomy (PEG) feeding. Important gaps in knowledge were found that were positively correlated with whether respondents had received relevant education. Referral for a PEG was considered to be appropriate for patients with advanced dementia by 31% of the GP compared with 10% of the consultants. Only 4% of these GP had received any training in this ethically-sensitive area at a time when they may be asked to countersign consent forms for patients who lack competence. So, what is the way forward? Positive steps are being taken in the undergraduate curriculum and Foundation Programme. Perhaps it is the responsibility of those doctors with the skills and opportunities to promote good nutritional knowledge in those doctors already practising in the UK.