bluuebunny/crossref_metadata_2025 huggingface dataset:
Photoelectrochemical roughening of p‐GaN for light extraction from GaN/InGaN light emitting diodes
Authors: Tamboli Adele C. , McGroddy Kelly C. , Hu Evelyn L.
Published: January 2009

A method for photoelectrochemical (PEC) etching of Ga‐face, p ‐type GaN is presented using GaN/InGaN heterostructures. This technique, which does not require any special epitaxial structure, flip chip bonding, or complicated processing, is used to roughen p ‐side‐up lightemitting diodes (LEDs) to increase extraction efficiency. The extraction efficiency is increased by 20 ± 5% for roughened LEDs compared to nearby unetched LEDs, without any effect on the electrical properties of the devices. This is the first report of rapid, external‐bias free PEC etching of p ‐type GaN, which could have broad applications to low‐damage selective etching for a variety of electronic and optical devices. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Off‐state breakdown in InAlN/AlN/GaN high electron mobility transistors
Authors: Kuzmik J. , Pozzovivo G. , Carlin J.‐F. , Gonschorek M. , Feltin E. , Grandjean N. , Strasser G. , Pogany D. , Gornik E.
Published: January 2009

Unpassivated InAlN/AlN/GaN high electron mobility transistors off‐state breakdown is analyzed for different gate‐to‐drain distances. The breakdown voltage linearly increases with the gate to drain distance reaching 350 V for a 10 μm contact separation; the sub‐threshold leakage current is < 10–5 A/mm. Similar breakdown voltages and leakage current are obtained on GaN buffer for two Ohmic contacts if their distance is the same. It is suggested that the breakdown is governed by injection/avalanche processes in the GaN buffer layer and is basically not affected by InAlN barrier. Our conclusions are further supported by measuring all currents in the three‐terminal configuration of the transistors before and during the breakdown and by using a drain current injection technique. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
GaN‐based deep green light emitting diodes on silicon‐on‐insulator substrates
Authors: Tripathy S. , Dadgar A. , Zang K. Y. , Lin V. K. X. , Liu Y. C. , Teo S. L. , Yong A. M. , Soh C. B. , Chua S. J. , Bläsing J. , Christen J. , Krost A.
Published: January 2009

We have demonstrated deep green InGaN/GaN light emitting diodes (LEDs) on 100 nm thick (111)‐oriented silicon‐on‐insulator (SOI) substrate. The LED structures are grown by metalorganic chemical vapour deposition. High‐resolution X‐ray diffraction and transmission electron microscopy have been used to characterize the structural quality of the LED layers. The room temperature electroluminescence (EL) spectrum from these LEDs is dominated by multiple interference peaks associated with the reflectivity changes at the bottom Si/SiO2 interfaces beneath AlN buffer. The spectral intensity of the LEDs in the deep green region is higher due to the larger substrate reflectance at longer wavelengths. A greater modulation in the spectral fringes in the longer wavelength regions is due to the presence of Fabry‐Perot modes. Such InGaN/GaN light emitting structures on reflective SOI may be useful for the realization of phosphor‐free white LEDs. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Study of diffusion and thermal stability of fluorine ions in GaN by Time‐of‐Flight Secondary Ion Mass Spectroscopy
Authors: Wang Maojun , Yuan Li , Xu Fujun , Shen Bo , Chen Kevin J.
Published: January 2009

The diffusion properties of fluorine ions in GaN are investigated by means of Time‐of‐Flight secondary ion mass spectroscopy. Instead of incorporating fluorine ions close to the sample surface by plasma, fluorine ion implantation with an energy of 180 keV is utilized to implant fluorine ions deep into the GaN bulk, preventing the surface effects from affecting the data analysis. It is found that the diffusion of fluorine‐ions in GaN is a dynamic process, featuring a two‐step process. A defect‐assisted diffusion model is proposed to account for the experimental observations. Fluorine ions tend to occupy Ga vacancies induced by fluorine ion implantation and diffuse to vacancy rich regions. The fluorine ions become stable after continuous vacancy chains are significantly reduced or removed by thermal annealing. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Impact of nitridation on structural and optical properties of MOVPE‐grown m‐plane GaN layers on LiAlO2
Authors: Mauder C. , Rahimzadeh Khoshroo L. , Behmenburg H. , Reuters B. , Bösing M. , Rzheutskii M. V. , Lutsenko E. V. , Yablonskii G. P. , Woitok J. F. , Chou M. M. C. , Heuken M. , Kalisch H. , Jansen R. H.
Published: January 2009

In this paper, we investigate the influence of the nitridation of LiAlO2 substrates on the growth of m‐plane (1‐100) GaN layers by metal‐organic vapour phase epitaxy (MOVPE). Before thin film deposition, we performed an in‐situ substrate pretreatment by exposing the wafer to NH3 for different times between no pretreatment and 300 s. The properties of subsequently grown layers show a significant dependency on this nitridation step. We find that this procedure is essential for obtaining pure m‐plane GaN films and has a beneficial effect on the X‐ray rocking curve (XRC) full width at half maximum (FWHM) value, which decreases by almost two orders of magnitude. Deposited layers with NH3 pretreatment also exhibit much smoother surfaces with a reduction of the root mean square (RMS) roughness value from ∼20 to ∼6 nm. Additionally, the nitridation greatly increases the GaN band edge emission intensity in room temperature (RT) photoluminescence (PL) spectroscopy. Furthermore, we compare the sensitivity of the substrate against water for uncoated LiAlO2 wafers with and without nitridation process. While the untreated surface shows a clear roughening when dipped into de‐ionized (DI) water for 5 min, we can see no significant impact on the nitridated substrate surface. This indicates a change in surface composition which protects the sensitive substrate surface and provides good conditions for the nucleation of high‐quality m‐plane GaN films. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
AlN/AlGaN/GaN/AlGaN multilayer heterostructures with quantum well channel on heat conducting substrates for power microwave transistors
Authors: Krasovitskiy Dmitry , Alexeev Alexey , Byrnaz Anton , Kokin Sergey , Pavlenko Maxim , Petrov Stanislav , Pogorelsky Michael , Pogorelsky Yury , Sokolov Igor , Sokolov Michael , Shkurko Alexey , Chaly Victor
Published: January 2009

Molecular beam epitaxy using ammonia as a nitrogen source is applied to obtain III‐nitride multilayer heterostructures having high structural quality and low dislocation density. To provide strong carrier confinement in two‐dimensional electron gas for collapse‐free transistor operation, GaN quantum well as thin as 5 nm was formed between AlGaN barrier layers of various Al content, keeping high sheet conductivity in 280‐350 Ohm/square range. Due to rather thick AlN “template” grown at extremely high (up to 1200 °C) substrate temperatures directly in the same growth run prior to the growth of heterostructure, technology developed on sapphire is easily transferred to alternative substrates, for example AlN/SiC or Si. In contrast to sapphire, where noticeable drop of transistor saturation current at drain voltages higher than 5‐10 V is usually observed, heat conducting substrates allow to avoid this negative thermal effect and no drop is observed at drain voltages up to 20 V and even higher. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Bulk GaN crystals and wafers grown by HVPE without intentional doping
Authors: Łucznik Bolesław , Pastuszka Bogdan , Weyher Jan L. , Kamler Grzegorz , Grzegory Izabella , Porowski Sylwester
Published: January 2009

In this work, bulk crystals of GaN were grown in multiple HVPE runs in order to get about 5 mm thick samples. Then the crystals were sliced in both polar and non‐polar orientations. Dominant morphological defects in GaN bulk crystals grown by HVPE on (0001) oriented substrates are polygonal pits of various depths. Since the pits are composed of semi‐polar surfaces, it is possible to recover their formation and growth history by optical microscopy and photochemical etching sensitive to the fluctuations in concentration of point defects. For example dark triangles on the non‐polar slice in the figure are traces of pits moving along growth direction thus leaving highly oxygen doped trace underneath. Analysis of distribution, properties and origin of these defects, based on measurements of polar and non‐polar slices of the bulk crystals is presented. One of reasons for the pits formation are inversion domains generated at different stages of the HVPE growth. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical polarisation anisotropy in a ‐plane GaN/AlGaN multiple quantum well structures
Authors: Badcock Tom J. , Dawson Philip , Kappers Menno J. , McAleese Clifford , Hollander Jonathan L. , Johnston Carol F. , Sridhara Rao Duggi V. , Sanchez Ana M. , Humphreys Colin J.
Published: January 2009

In this paper we report on the optical properties of a series of a ‐plane GaN/AlGaN multiple quantum well structures of varying well width. The low temperature photoluminescence spectrum of each structure is characterised by two distinct emission bands, both of which shift to higher energy with decreasing well thickness. The origin of the lower energy emission band is attributed to the recombination of carriers trapped in regions of the quantum wells intersected by basal plane stacking faults. The higher energy feature is assigned to localised exciton recombination at well width fluctuations. We have used photoluminescence excitation spectroscopy to reveal details of the bandstructure of the quantum wells. Excitation with unpolarised light resulted in the observation of exciton transitions associated with the n = 1 and n = 2 electron sub‐bands. For linearly polarised (E⊥c and E‖c) excitation, both the transitions observed with unpolarised light were shown to consist of overlapping transitions involving heavy and light hole like valence subbands. Their observed polarisation anisotropy was attributed to anisotropic biaxial compressive strain in the GaN film. As well as the exciton transitions we were also able to resolve well defined continuum edges in some of the excitation spectra. This enabled us to estimate the exciton binding energy of the n = 1 heavy and light hole states for quantum wells of differing width. Values were found to lie in the range of 38 to 76 ±5 meV. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Therapeutic advantages of medicinal herbs fermented with Lactobacillus plantarum, in topical application and its activities on atopic dermatitis
Authors: Joo Seong Soo , Won Tae Joon , Nam Sang Yoon , Kim Yun‐Bae , Lee Young Chul , Park So‐Yong , Park Hee Yong , Hwang Kwang Woo , Lee Do Ik
Published: January 2009

The use of herbal medicines in the therapeutic treatment of atopic dermatitis (AD) has been suggested recently. The present study examined whether selected herbal extracts fermented in Lactobacillus plantarum (FHE) possessed anti‐AD properties. In addition, the study assessed the increased bioavailability of these herbal extracts both in vitro and in vivo. The data from these experiments revealed that FHE inhibited the proliferation of splenic T and B cells in a dose‐dependent manner, when activated with their mitogens. Moreover, the expression of Th1/Th2 mRNA cytokines (IL‐2, IL‐4, IL‐5, IL‐13) from mouse splenocytes was inhibited severely as was cyclosporine A. Furthermore, the release of β‐hexosaminidase in RBL‐2H3 mast cells was suppressed significantly. FHE also reduced the plasma level of IgE in dust mite extract‐induced AD‐like NC/Nga mice. More dramatic results were found in the histological changes, which were observed by hematoxylin–eosin and toluidine blue staining, as well as in the macroscopic features on dorsal lesions of AD‐like NC/Nga mice. In conclusion, the results presented in this study suggest that FHE may have therapeutic advantages for the treatment of AD due to its increased immune‐suppressive and increased absorptive effects, which were fortified by L. plantarum fermentation. Copyright © 2009 John Wiley & Sons, Ltd.
Maximum‐Likelihood Estimation of Predictive Uncertainty in Probabilistic QSAR Modeling
Authors: Pery Alexandre , Henegar Adina , Mombelli Enrico
Published: January 2009

Quantitative Structure–Activity Relationships (QSAR) models routinely predict biological activities of interest and the resulting predictions are meaningful only if their uncertainty is properly characterized. Consequently, the availability of a methodology allowing the estimation of predictive uncertainty for QSAR predictions is an issue of practical relevance both for scientific research and for regulatory purposes. In this paper, we present a novel statistical methodology based on maximum likelihood estimation that enables the QSAR prediction of biological activities and the probabilistic assessment of the uncertainty attached to individual predictions. In the formulation of the methodology, chemicals are positioned in a descriptor hyperspace whose coordinates are defined by a set of orthogonal axis such as the principal components determined by Partial Least Squares (PLS) regressions. Each training set chemical contributes in predicting the probability for the query chemical to be active and such a contribution is weighted with respect to the Euclidean distance separating the two chemicals. This study explains how uncertainty can be probabilistically assessed during QSAR modeling of molecular databases and compares the performance of the predictive methodology to published data.
Density fitting for derivatives of Coulomb integrals in ab initio calculations using mixed Gaussian and plane‐wave basis
Authors: Čársky Petr
Published: January 2009

This article presents an efficient way for evaluation of Coulomb integrals of the type (k1 (1)k2 (1)|g1 (2)g2 (2)) and their derivatives with respect to nuclear coordinates by means of density fitting. Symbols k1 andk2 stand for plane‐wave functions and g1 and g2 for gaussians. The study was undertaken with the objective to accelerate electronic structure and electron scattering calculations in which a mixed Gaussian and plane‐wave basis set is used. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
Theoretical study on the interlay of hydrogen bonds in the trimers involving HCN and water
Authors: Li Qingzhong , Wang Xilin , Cheng Jianbo , Li Wenzuo , Gong Baoan , Sun Jiazhong
Published: January 2009

In this study, the hydration of hydrogen cyanide (HCN) has been investigated by means of quantum chemical ab initio calculations at the MP2/6‐311++G(3df,2p) level. Various HCN· · ·( H2O)2and (HCN)2· · ·H2O complexes were optimized. Geometrics and energetics in these complexes have been analyzed. The hydration of the H atom leads to an elongation of the NC and CH bonds, whereas the hydration of the N atom results in a contraction of the NC bond and a little elongation of the CH bond. The interaction energy between each molecule pair in the trimers (except in HCNH2OH2O trimer) is increased relative to that in the respective dimer. The cooperativity of hydrogen bond in HCNH2OH2O trimer plays a negative contribution to the total interaction energy of the complex, whereas that in the other trimers is a positive contribution. Geometry and energy in H2OH2OOHCNH2O tetramer have also been analyzed. The binding energies in the trimers and tetramer have been studied by means of many‐body interaction analysis. The mechanism of HCN hydration was suggested. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
Conformation and coordination of 1‐phenyl‐3‐methyl‐4‐benzal‐5‐pyrazolone thiosemicarbazone: A density functional study
Authors: Wu Dongling , Jia Dianzeng , Liu Lang , Liu Anjie
Published: January 2009

Density functional theory method has been employed to study the molecular properties of four tautomers and their deprotonated species of 1‐phenyl‐3‐methyl‐4‐benzal‐5‐pyrazolone thiosemicarbazone. The solvent effect has been investigated by applying the polarizable continuum model of the self‐consistent reaction field theory. The condensed Fukui functions have been calculated to assess the relative reactivity of different sites in the ligands. Molecular electrostatic potential is obtained as an additional molecular descriptor for revealing the regions of the molecular species to which an electrophile would initially be attracted. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
Elongation method for calculating excited states of aromatic molecules embedded in polymers
Authors: Pomogaev Vladimir , Gu Feng Long , Pomogaeva Anna , Aoki Yuriko
Published: January 2009

Photophysical properties of polyethylene structures embedding aromatic fragments (benzene, anthracene, 4‐dicyanomethylene‐4H‐pyran, tryptophan, and estradiol) responsible for existence lowest electronically excited states were studied by new technique involving the elongation method applied to quantum‐chemical calculations. Absorption spectra and some photophysical properties were obtained. The comparison between the elongation and the conventional calculations was made, and it is shown that the elongation method is a powerful tool to determine the excited states as well as optical properties for large systems. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
Robotic ultrasound‐guided prostate intervention device: system description and results from phantom studies
Authors: Ho H.S.S. , Mohan P. , Lim E.D. , Li D.L. , Yuen J.S.P. , Ng W.S. , Lau W.K.O. , Cheng C.W.S.
Published: January 2009

Background

We introduce the first robotic ultrasound‐guided prostate intervention device and evaluate its safety, accuracy and repeatability.

Methods

The robotic positioning system (RPS) determines a target's x, y and z axes. It is situated with a biplane ultrasound probe on a mobile horizontal platform. The integrated software acquires ultrasound images for three‐dimensional (3D) modelling, coordinates target planning and directs the RPS.

Results

The egg phantom evaluates the software's safety and workflow protocol. Two random targets are planned in each quadrant and biopsy needles are inserted. All were within three separate eggs. Metal wire tips are targeted and their distances from the biopsy needle tips are measured. With 20 wires, < 1 mm accuracy is obtained. Repeatability is demonstrated when previous positions are returned to with similar accuracy.

Conclusion

Our device demonstrates safety in a defined boundary with a repeatable accuracy of < 1 mm. It can be used for accurate prostate biopsy and treatment delivery. Copyright © 2009 John Wiley & Sons, Ltd.
Managing water‐use trade‐offs in a semi‐arid river delta to sustain multiple ecosystem services: a modeling approach
Authors: Schlüter Maja , Leslie Heather , Levin Simon
Published: January 2009

Managing trade‐offs among water uses in a river basin to sustain multiple ecosystem services is crucial for adaptation to changing river flow regimes. Here we analyze the trade‐off between irrigation and fisheries in the Amudarya, a semi‐arid river basin in Central Asia, using an optimal control and an agent‐based modeling approach. With the optimal control approach (OCA), we identify the economic and ecological conditions for water sharing in a regime where a social manager controls water withdrawals and fish harvesting. With the agent‐based model (ABM), we relax some of the assumptions of the OCA to investigate how localized, individual agents with varied water use histories adapt their water use activities to local resource conditions. Variation in the farmers’ initial labor allocations to the two activities results in regimes with only one activity or both. Global returns and income equality are highest in a mixed regime. The mixed regimes also are more robust to water variability because fishing activities can compensate for decreased agricultural performance in the midstream regions. Thus, allowing for multiple uses can improve the coupled social‐ecological system's performance and its resilience. We also observe a lock‐in effect similar to the current situation in the Amudarya, where agriculture is the dominant water use and transition to a more balanced allocation has proven to be extremely difficult. As in the ABM, this can to some extent be attributed to the difficulties of achieving sufficient revenues from fishing when agricultural activities upstream are high. Regulations or incentives are needed to overcome those barriers, and to facilitate progress towards integrated water management.
Attention management as a treatment for chronic pain
Authors: Elomaa Minna M. , de Williams Amanda C. , Kalso Eija A.
Published: January 2009

Attention management is often included in cognitive‐behavioural treatments (CBT). The aim of this study was to evaluate the effects of attention management strategies in the treatment for chronic pain. The present pilot study consisted of six weekly 90‐min treatment sessions and was based on a CBT attention management manual describing techniques such as attention diversion, imagery and mindfulness exercises. The intended outcomes were reduction in pain‐related anxiety and hypervigilance to pain and decrease in pain impact of everyday life, measured by self‐report. Information was collected at baseline, pre‐treatment, post‐treatment, and at 3 and 6 months follow‐up. The results at the end of treatment, and at 3‐month follow‐up, show significant reductions in pain‐related anxiety, hypervigilance and interference of pain (effect sizes 0.40–0.90). Reduction in pain‐related interference and anxiety remained at the 6‐month follow‐up. The results indicate that attention control skills can be a useful method to reduce anxiety in the short term. Clinical implications of the results are discussed.
Pensée 2: Theorizing Arab Nationalism
Authors: Choueiri Youssef M.
Published: January 2009

Arab nationalism has received the attention of a fairly large number of scholars since its inception at the turn of the 20th century. It did not receive its first full treatment, however, until 1938, when George Antonius published The Arab Awakening. This book set the tone for much that was to follow—as statements of confirmation, elaboration, or refutation.
Pensée 4: Out with the Old, In with the New
Authors: Lawson Fred H.
Published: January 2009

Historical scholarship on Arab nationalism has experienced a conceptual revolution over the last two decades. It is now widely accepted among historians that local identities and loyalties have been crucial components of nationalist thought and action from the very beginning; it is equally well established that the line between nationalism and various elements of Islam is much harder to draw than one might imagine. In addition, there is solid evidence that nationalism across the Arab world took shape, arguably as an unintended consequence, out of sustained interaction among conflicting elite and popular conceptions of political community. Moreover, it turns out to be important to differentiate Arab nationalism as a cluster of ideological principles from Pan-Arabism as a set of diplomatic practices that constituted a basic component of regional statecraft, initially at the time the Ottoman Empire found itself disintegrating and later on as the newly independent states of the Middle East and North Africa experimented with ways to get along simultaneously with one another and with outside powers.
OVERVIEW: ENGAGING THE ARAB HUMAN DEVELOPMENT REPORT 2005 ON WOMEN
Authors: Abu-Lughod Lila , Adely Fida J. , Hasso Frances S.
Published: January 2009

The Arab Human Development Report 2005: Towards the Rise of Women in the Arab World (AHDR 2005), published in Arabic with English and French translations, was launched at the end of 2006. With a title carefully crafted to avoid Western development buzzwords like “empowerment” and to signal the inclusion of all women living in the region, it is the third in a series of detailed studies meant to unpack the themes of the original overview report that garnered both acclaim and criticism when it was published in 2002. The other two topical reports examine what were billed as “deficits” in knowledge and in freedom. This one tackles what the original report framed as the third major obstacle to the flourishing of the Arab world: the deficit in gender equality.
DIALECTS OF WOMEN'S EMPOWERMENT: THE INTERNATIONAL CIRCUITRY OF THEARAB HUMAN DEVELOPMENT REPORT 2005
Authors: Abu-Lughod Lila
Published: January 2009

The ethical and political dilemmas posed by the construction and international circulation of discourses on women's rights in the Middle East are formidable. The plight of “Muslim women” has long occupied a special place in the Western political imagination, whether in colonial officials' dedication to saving them from barbaric practices or development projects devoted to empowering them. In the past fifteen years or so, through a series of international conferences and the efforts of feminist activists, women's rights have come to be framed successfully as universal human rights. Building on the U.N. conferences on women that started in 1975 and led to other initiatives, the appropriate arena of women's rights work has been redefined from the national to the international.
A REPLY TO JUDITH E. TUCKER'S A LOOK BACK: “THE NAIM-ANDONIAN DOCUMENTS” BY VAHAKN DADRIAN (IJMES 40 [MAY 2008]: 171–79)
Authors: Ataöv Türkkaya
Published: January 2009

“The truth is the whole!” wrote Hegel. The reprint of V. N. Dadrian's article on the so-called Andonian “documents” steers clear of many pertinent facts related to Armenian-Turkish relations and falls short of Hegel's maxim. Dadrian reduces the topic to a one-sided indoctrination, limiting his references to selected narratives and omitting all evidence that contradicts mainstream Armenian views. His article bypasses the initial Armenian massacre of Muslim Anatolians, the Armenian-led revolt in the Ottoman province of Van, and Armenian shedding of blood in about a dozen wars or armed clashes. He attacks the Turks presented with the posture of a prosecuting attorney in tones so biased that today's social scientists would define them as racist.
Convergent and predictive validity of two computerized attention tests in brain-damaged patients
Authors: Beck Lydia , Heusinger Anne , Boecker Maren , Niemann Hendrik , Gauggel Siegfried
Published: January 2009

Although computerized attention tests are used frequently, our knowledge about the convergent and predictive validity of these tests is limited. In the present study, 47 stroke and traumatic brain injury patients performed the Attention Network Test (ANT) and corresponding subtests of the Test for Attentional Performance (TAP). In addition, patients and staff completed the Attention Deficits Questionnaire (ADQ). Considering corresponding ANT and TAP subtests, significant correlations (r = .55 – .71) were found for alerting and orienting subtests and overall reaction time. Comparison of subtests of the two attention tests with staff reported deficits in the ADQ revealed moderate to high correlations for ANT (r = .62 – .70) and TAP (r = .36 – .86). The predictive validity of different subtests varies only sightly. The overall reaction time seems to be the best predictor of rated attention deficits. Findings support the convergent and predictive validity of both computerized attention tests.
Entscheiden bei Morbus Parkinson – eine Übersicht
Authors: Sinz H. , Benke T. , Poewe W. , Delazer M.
Published: January 2009

Die Fähigkeit Entscheidungen zu treffen ist im täglichen Leben von zentraler Bedeutung. Patienten mit kognitiven Einschränkungen sind oft mit schwierigen Entscheidungen konfrontiert. Auch Patienten mit Morbus Parkinson (MP) weisen häufig kognitive Leistungsminderungen, insbesondere der exekutiven Funktionen, auf. Zahlreiche Arbeiten berichteten in den letzten Jahren über Impulskontrollstörungen (z. B. pathologisches Spielen) bei MP Patienten. Im Vergleich dazu gibt es wenige Studien, welche das Entscheidungsverhalten von MP Patienten ohne Impulskontrollstörungen anhand von Entscheidungsaufgaben untersucht haben. Der Artikel gibt eine Übersicht über in der neueren Forschung häufig verwendete experimentelle Verfahren zum Entscheidungsverhalten und diskutiert den Zusammenhang zwischen Entscheidungsverhalten und exekutiven Funktionen. In einem Überblick zu Entscheidungen unter Unsicherheit und unter Risiko bei MP Patienten zeigen sich heterogene Ergebnisse im Hinblick auf die Gesamtleistung in Entscheidungsaufgaben. Diskutiert wird der Zusammenhang mit anderen kognitiven Leistungen, sowie der Einfluss dopaminerger Medikation. Zusätzlich widmet sich ein Abschnitt Impulskontrollstörungen bzw. dem dopaminergen Dysregulationssyndrom.
Versorgungsforschung in der Klinischen Neuropsychologie – eine Standortbestimmung
Authors: Heel Sabine , Fischer Sonja , Fischer Stefan , Grässer Tobias , Hämmerling Ellen , Wendel Claudia
Published: January 2009

Zunächst führt dieser Artikel in die wesentlichen Begrifflichkeiten und Zielstellungen der Versorgungsforschung ein. Er befasst sich dann mit der Frage, wie die einzelnen Teildisziplinen der Versorgungsforschung, (1) die Bedarfsforschung, (2) die Inanspruchnahmeforschung, (3) die Organisationsforschung, (4) das Health Technology Assessment, (5) die Versorgungsökonomie, (6) die Qualitätsforschung und zuletzt (7) die Versorgungsepidemiologie konzeptionell zu fassen sind, und wie sie für neuropsychologische Anliegen ausformuliert werden müssen. In diesem Zusammenhang werden die in den einzelnen Bereichen jeweils vorliegenden versorgungsrelevanten Studienergebnisse referiert. Soweit es zulässig ist, werden Bedarfe für die Versorgungsforschung und Versorgungspraxis in der Neurorehabilitation daraus abgeleitet und Anregungen für die weitere empirische Forschung formuliert. Der Artikel bezieht sich – entsprechend seines Anliegens – ausschließlich auf Studien, die sich mit der Situation der deutschen Neurorehabilitation befassen.
Jugendhilfebedarf nach stationärer kinder- und jugendpsychiatrischer Behandlung
Authors: Beck Norbert , Warnke Andreas
Published: January 2009

Zusammenfassung: Fragestellung: Neuere Untersuchungen belegen die hohe Prävalenz kinder- und jugendpsychiatrischer Störungen bei Heimkindern. In dieser Untersuchung wird der Frage nachgegangen, wie hoch der Bedarf an Jugendhilfemaßnahmen im Anschluss an eine stationäre kinder- und jugendpsychiatrische Behandlung ist. Methodik: Es wurde die Basisdokumentation der stationären Patienten von 2001 bis 2005 der Würzburger Universitätsklinik für Kinder- und Jugendpsychiatrie und Psychotherapie mit der Fragestellung der indizierten oder realisierten Jugendhilfemaßnahme im Anschluss an die Behandlung analysiert. Weiter wurde die Frage gestellt, welche Faktoren das Risiko für einen Jugendhilfebedarf im Anschluss an die stationäre Behandlung verändern. Ergebnis: Bei fast 50% der in der Klinik behandelten Kinder und Jugendlichen war ein Jugendhilfebedarf indiziert, direkt umgesetzt wurde nur die Hälfte. Bei mehr als jeder dritten Maßnahme handelte es sich um eine stationäre Jugendhilfemaßnahme. Ein früher Beginn der Störung, abweichende Elternsituation, externale Störung und eine hohe Rate psychosozialer Risikofaktoren erhöhen das Risiko für einen Jugendhilfebedarf.
Powerful electromagnetic waves for active environmental research in geospace
Authors: Leyser T. B. , Wong A. Y.
Published: January 2009

Powerful electromagnetic (EM) waves can exert well‐defined influence on the atmosphere, ionosphere, and magnetosphere. These active EM interactions can provide spatiotemporal information on the near‐Earth space environment (geospace). Objectives include remote monitoring and controlling of a wide range of parameters of geospace, controlling properties of the ionosphere and magnetosphere, as well as interaction with large‐scale natural energy sources. In addition, applications such as mitigation of atmospheric pollutants and solar power satellites are discussed. Studies of EM wave interactions also contribute to the knowledge of anthropogenic effects in the geospace environment, such as the increasing use of EM radiation.
Temperature response in the Altai region lags solar forcing
Authors: Eichler Anja , Olivier Susanne , Henderson Keith , Laube Andreas , Beer Jürg , Papina Tatyana , Gäggeler Heinz W. , Schwikowski Margit
Published: January 2009

The role of the sun on Earth's climate variability is still much debated. Here we present an ice core oxygen isotope record from the continental Siberian Altai, serving as a high‐resolution temperature proxy for the last 750 years. The strong correlation between reconstructed temperature and solar activity suggests solar forcing as a main driver for temperature variations during the period 1250–1850 in this region. The precisely dated record allowed for the identification of a 10–30 year lag between solar forcing and temperature response, underlining the importance of indirect sun‐climate mechanisms involving ocean‐induced changes in atmospheric circulation. Solar contribution to temperature change became less important during industrial period 1850–2000 in the Altai region.
Robustness of multiple equilibria in the global ocean circulation
Authors: Huisman S. E. , Dijkstra H. A. , von der Heydt A. , de Ruijter W. P. M.
Published: January 2009

In an idealized Atlantic‐Pacific ocean model we study the steady state solutions versus freshwater input in the northern North Atlantic. We find that four different states, the Conveyor (C), the Southern Sinking (SS), the Northern Sinking (NS) and the Inverse Conveyor (IC), appear as two disconnected branches of solutions, where the C is connected with the SS and the NS with the IC. We argue that the latter has the intriguing consequence that the parameter volume for which multiple steady states exist is greatly increased.
An optimality‐based model of the dynamic feedbacks between natural vegetation and the water balance
Authors: Schymanski S. J. , Sivapalan M. , Roderick M. L. , Hutley L. B. , Beringer J.
Published: January 2009

The hypothesis that vegetation adapts optimally to its environment gives rise to a novel framework for modeling the interactions between vegetation dynamics and the catchment water balance that does not rely on prior knowledge about the vegetation at a particular site. We present a new model based on this framework that includes a multilayered physically based catchment water balance model and an ecophysiological gas exchange and photosynthesis model. The model uses optimization algorithms to find those static and dynamic vegetation properties that would maximize the net carbon profit under given environmental conditions. The model was tested at a savanna site near Howard Springs (Northern Territory, Australia) by comparing the modeled fluxes and vegetation properties with long‐term observations at the site. The results suggest that optimality may be a useful way of approaching the prediction and estimation of vegetation cover, rooting depth, and fluxes such as transpiration and CO2 assimilation in ungauged basins without model calibration.
Acute Nicotine Reduces Brain Arachidonic Acid Signaling in Unanesthetized Rats
Authors: Chang Lisa , Rapoport Stanley I , Nguyen Henry N , Greenstein Dede , Chen Mei , Basselin Mireille
Published: January 2009

Nicotine exerts its central effects by activating pre- and postsynaptic nicotinic acetylcholine receptors (nAChRs). Presynaptic nAChRs modulate the release of many neurotransmitters that bind to postsynaptic receptors. These may be coupled to the activation of cytosolic phospholipase A2(cPLA2), which hydrolyzes arachidonic acid (AA) from membrane phospholipids. We hypothesized that nicotine would modify brain signaling involving AA by binding to nAChRs. Nicotine (0.1 mg/kg, subcutaneously) or saline was injected 2 or 10 mins before infusing [1-14C]AA in unanesthetized rats. The AA incorporation coefficient k∗ (a marker of the AA signal) was measured in 80 brain regions by quantitative autoradiography. Nicotine, compared to saline, when administrated 2 mins before [1-14C]AA infusion, significantly decreased k∗ for AA in 26 regions, including cerebral cortex, thalamus, and habenula—interpeduncular regions, by 13% to 45%. These decreases could be entirely prevented by pretreatment with mecamylamine (1.0 mg/kg, subcutaneously). When administered 10 mins before [1-14C]AA infusion, nicotine did not alter any value of k∗. In summary, nicotine given to unanesthetized rats rapidly reduces signaling involving AA in brain regions containing nAChRs, likely by modulating the presynaptic release of neurotransmitters. The effect shows rapid desensitization and is produced at a nicotine dose equivalent to smoking one cigarette in humans.
Dissociation and Protection of the Neurovascular Unit after Thrombolysis and Reperfusion in Ischemic Rat Brain
Authors: Yamashita Toru , Kamiya Tatsushi , Deguchi Kentaro , Inaba Toshiki , Zhang Hanzhe , Shang Jingwei , Miyazaki Kazunori , Ohtsuka Aiji , Katayama Yasuo , Abe Koji
Published: January 2009

In the ischemic brain, reperfusion with tissue plasminogen activator (tPA) sometimes causes catastrophic hemorrhagic transformation (HT); however, the mechanism remains elusive. Here, we show that the basement membrane, and not the endothelial cells, is vulnerable to ischemic/reperfusion injury with tPA treatment. We treated a spontaneously hypertensive rat model of middle cerebral artery occlusion (MCAO) with vehicle alone, tPA alone, or a free radical scavenger, edaravone, plus tPA. Light and electron microscopic analyses of each microvascular component revealed that the basement membrane disintegrated and became detached from the astrocyte endfeet in tPA-treated animals that showed HT. On the other hand, edaravone prevented the dissociation of the neurovascular unit, dramatically decreased the HT, and improved the neurologic score and survival rate of the tPA-treated rats. These results suggest that the basement membrane that underlies the endothelial cells is a key structure for maintaining the integrity of the neurovascular unit, and a free-radical scavenger can be a viable agent for inhibiting tPA-induced HT.
The ribonome: a dominant force in co‐ordinating gene expression
Authors: Mansfield Kyle D. , Keene Jack D.
Published: January 2009

The ribonome is the total cellular complement of RNAs and their regulatory factors functioning dynamically in time and space within ribonucleoprotein complexes. We theorize that the ribonome is an ancient central co‐ordinator that has evolved to communicate on multiple levels to the proteome on the one hand (feed‐forward), and the transcriptome and RNA processing machinery on the other (feed‐back). Furthermore, the ribonome can potentially communicate to other cells horizontally with implications for biological information transfer and for the evolution of both RNA and DNA operating systems. The post‐transcriptional RNA operon theory of co‐regulated gene expression accounts for the co‐ordinated dynamics of RNA‐binding proteins within the cellular ribonome, thus allowing for the recombination and remodelling of the RNPs (ribonucleoproteins) to generate new combinations of functionally related proteins. Thus, post‐transcriptional RNA operons form the core of the ribonomic operating system in which both their control and co‐ordination govern outcomes. Within the ribonome, RNA‐binding proteins control one another's mRNAs to keep the global mRNA environment in balance. We argue that these post‐transcriptional ribonomic systems provide an information management and distribution centre for evolutionary expansion of multicellularity in tissues, organs, organisms, and their communities.
Killing niche competitors by remote-control bacteriophage induction
Authors: Selva Laura , Viana David , Regev-Yochay Gili , Trzcinski Krzysztof , Corpa Juan Manuel , Lasa íñigo , Novick Richard P. , Penadés José R.
Published: January 2009

A surprising example of interspecies competition is the production by certain bacteria of hydrogen peroxide at concentrations that are lethal for others. A case in point is the displacement of
Staphylococcus aureus
by
Streptococcus pneumoniae
in the nasopharynx, which is of considerable clinical significance. How it is accomplished, however, has been a great mystery, because H
2
O
2
is a very well known disinfectant whose lethality is largely due to the production of hyperoxides through the abiological Fenton reaction. In this report, we have solved the mystery by showing that H
2
O
2
at the concentrations typically produced by pneumococci kills lysogenic but not nonlysogenic staphylococci by inducing the SOS response. The SOS response, a stress response to DNA damage, not only invokes DNA repair mechanisms but also induces resident prophages, and the resulting lysis is responsible for H
2
O
2
lethality. Because the vast majority of
S. aureus
strains are lysogenic, the production of H
2
O
2
is a very widely effective antistaphylococcal strategy. Pneumococci, however, which are also commonly lysogenic and undergo SOS induction in response to DNA-damaging agents such as mitomycin C, are not SOS-induced on exposure to H
2
O
2.
This is apparently because they are resistant to the DNA-damaging effects of the Fenton reaction. The production of an SOS-inducing signal to activate prophages in neighboring organisms is thus a rather unique competitive strategy, which we suggest may be in widespread use for bacterial interference. However, this strategy has as a by-product the release of active phage, which can potentially spread mobile genetic elements carrying virulence genes.
PolV(PolIVb) function in RNA-directed DNA methylation requires the conserved active site and an additional plant-specific subunit
Authors: Lahmy Sylvie , Pontier Dominique , Cavel Emilie , Vega Danielle , El-Shami Mahmoud , Kanno Tatsuo , Lagrange Thierry
Published: January 2009

Two forms of a plant-specific RNA polymerase (Pol), PolIV(PolIVa) and PolV(PolIVb), currently defined by their respective largest subunits [NRPD1(NRPD1a) and NRPE1(NRPD1b)], have been implicated in the production and activity of 24-nt small RNAs (sRNAs) in RNA-directed DNA methylation (RdDM). Prevailing models support the view that PolIV(PolIVa) plays an upstream role in RdDM by producing the 24-nt sRNAs, whereas PolV(PolIVb) would act downstream at a structural rather than an enzymatic level to reinforce sRNA production by PolIV(PolIVa) and mediate DNA methylation. However, the composition and mechanism of action of PolIV(PolIVa)/PolV(PolIVb) remain unclear. In this work, we have identified a plant-specific PolV(PolIVb) subunit, NRPE5a, homologous to NRPB5a, a common subunit shared by PolI-III and shown here to be present in PolIV(PolIVa). Our results confirm the combinatorial diversity of PolIV(PolIVa)/PolV(PolIVb) subunit composition and indicate that these plant-specific Pols are eukaryotic-type polymerases. Moreover, we show that
nrpe5a-1
mutation differentially impacts sRNAs accumulation at various PolIV(PolIVa)/PolV(PolIVb)-dependent loci, indicating a target-specific requirement for NRPE5a in the process of PolV(PolIVb)-dependent gene silencing. We then describe that the triad aspartate motif present in the catalytic center of PolV(PolIVb) is required for recapitulation of all activities associated with this Pol complex in RdDM, suggesting that RNA polymerization is important for PolV(PolIVb) to perform its regulatory functions.
Hysterectomy on benign indications in Sweden 1987–2003: A nationwide trend analysis
Authors: LUNDHOLM CECILIA , FORSGREN CATHARINA , JOHANSSON ANNA L.V. , CNATTINGIUS SVEN , ALTMAN DANIEL
Published: January 2009

Objective. To investigate the annual rates, types and indications for hysterectomy on benign indications in Sweden 1987–2003. Design. A nationwide register‐based cohort study. Setting. The Swedish Inpatient Register. Population. All women hysterectomized for benign disease in Sweden from 1987 through 2003 (n = 121,947). Main outcome measure. Hysterectomy on benign indications calculated as proportions or rates/100,000 person‐years. Results. From 1987 to 1999, the annual overall hysterectomy rate increased from 178 to 232/100,000 person‐years. Thereafter, the overall hysterectomy rate declined and phased out around 210/100,000 person‐years in 2003, a decrease of 11%. Comprising only 4% of hysterectomies performed in 1987, vaginal hysterectomy increased to 31% in 2003. Rates of vaginal hysterectomy by prolapse indication increased by a five‐fold, whereas rates of vaginal hysterectomy by other benign indications increased by a near 20‐fold. Total and subtotal abdominal hysterectomy decreased from 63% and 32%, respectively, in 1987, to 48% and 18% in 2003. Conclusion. The overall rate of hysterectomy on benign indications has remained reasonably stable in Sweden over the last decade. Major trends involved a considerable decrease in rates of abdominal hysterectomy, increased use of vaginal hysterectomy and increased number of hysterectomies performed for pelvic organ prolapse.
Young Swedish women's experience of pain and discomfort during sexual intercourse
Authors: ELMERSTIG EVA , WIJMA BARBRO , SWAHNBERG KATARINA
Published: January 2009

Objective. To study experience and prevalence of (1) pain related to first sexual intercourse; (2) pain and/or discomfort associated with sexual intercourse during the previous month; and (3) associations between these experiences. Design. Cross‐sectional study. Setting. A youth center in southeast Sweden. Sample. Three hundred consecutive women, aged 13–21 (response rate 98%). Method. During a two‐month period, women consulting a youth center, participated in a questionnaire study. Main outcome measures. Pain and/or discomfort during sexual intercourse. Results. The majority of the participants, 98%, had had sexual intercourse and of those, 65% reported pain related to first sexual intercourse. Forty‐nine percent (99/203) of those who reported sexual intercourse during the previous month had experienced coital pain and/or discomfort during that period, and for almost every second woman (46/99), those experiences constituted a problem. We found no association between experience of pain during first sexual intercourse and pain and/or discomfort during the previous month. Conclusions. Prevalence of pain and/or discomfort associated with sexual intercourse is high among women visiting a youth center. Our results show that coital pain in young women is a problem which needs to be further explored.