bluuebunny/crossref_metadata_2025 huggingface dataset:
Heterolocal Identities? Counter‐Urbanisation, Second Homes, and Rural Consumption in the Era of Mobilities
Authors: Halfacree Keith
Published: March 2011

This paper forms part of a critical engagement with the aspects of the core population geography concept of ‘counterurbanisation’. It argues that contextualising counterurbanisation within the ‘era of mobilities’ has profound consequences for the concept. After introducing the era of mobilities and its implications for social science, migration's central and multiple places within this discourse are outlined. The paper then examines one set of ideas, ‘dynamic heterolocalism’, that facilitates the understanding of the existential significance today of the circulatory expressions of migration. Returning to counterurbanisation, the paper draws into its orbit the consumers of rural second homes, understanding of which has also increasingly adopted a quasi‐heterolocal tone. An inclusive model of what is then recast terminologically as ‘counter‐urbanisation’ posits it as an extremely heterodox concept, potentially embracing not only second‐home owners but also diverse other consumers of rural space or rural sojourners. The paper concludes by reiterating the sustained centrality of ‘rurality’ to counterurbanisation, second‐home consumption, and other expressions of identity within the era of mobilities. Copyright © 2011 John Wiley & Sons, Ltd.
Exciton spectra in thin crystals
Authors: Harper P. G. , Hilder J. A.
Published: March 2011

A theory is presented of the observed dependence of exciton series spectra on crystal thickness [2,3]. When the latter is comparable to the Wannier exciton radius the effective confinement of the exciton bound states, by the uncertainty principle, raises the kinetic energy. This confinement is introduced by the boundary condition which requires the Wannier wave function to vanish outside the crystal. Allowance is made for thick crystal anisotropy, and its effects on the binding energy calculated for the low excited states.
Free carrier absorption in n‐type CdTe crystals
Authors: Yamada S. , Kawasaki Y. , Nishida O.
Published: March 2011

Optical absorption is investigated in In‐doped n‐type CdTe crystals between 2.5 and 16 μm. The measurements are made at 295 and 473°K. The absorption coefficient increases smoothly with wavelength, and this is almost certainly due to free carrier absorption. From the absorption curves, it is concluded that the electrons are scattered mainly by optical phonons and partially by ionized impurities.
Diffusion concentration distribution near an idealized contact spot
Authors: Cramer K. R. , Richards K. J.
Published: March 2011

The distribution of the concentration of a diffusing substance near an idealized contact spot is determined analytically for unsteady self‐diffusion across only the contact region. The results demonstrate that the influence of the contact spot is restricted to less than ten spot radii in the radial direction and less than four in the axial direction.
Vectorial selective surface effects in the optical absorption and photoelectric emission of thin metal films
Authors: Meessen A.
Published: March 2011

The “surface effect” is expected to become observable in the photoelectric emission, and even more early in the optical absorption of very thin metal films. It corresponds to a modified Drude absorption where the electron mean free path is of the order of magnitude of the film thickness. But there is a strong “vector effect” in films with perfectly plane surfaces. The quantum mechanical calculation yields the same result as the modified classical Drude theory, with the additional prediction of a film‐thickness dependent absorption‐threshold. Other related surface effects are briefly discussed, and it is suggested that the excitation of surface plasmons may also lead to a “vectorial, selective photoelectric emission”.
Magnetoabsorptionsmessungen an Tellur
Authors: Grosse P. , Winzer K.
Published: March 2011

Im Bereich der elektronischen Bandkante wurden an Tellur Absorptionsspektren hoher Auflösung für die beiden Hauptpolarisationsrichtungen gemessen. Der Einfluß von Magnetfeldern bis 32 kG auf diese Spektren wurde für die drei Orientierungen (E ⟂ c, B ⟂ c, B ‖ E), (E ‖ c, B ‖ c, B ‖ E) und (E ‖ c, B ⟂ c, B ⟂ E) untersucht. Exzitonen werden für beide Polarisationsrichtungen nachgewiesen. Die Extrapolation der Magnetoabsorptionsspektren auf B = 0 ergibt für beide Polarisationsrichtungen den gleichen Bandabstand von Eg = 0,335 eV bei 10°K. Aus den drei verschiedenen ausgewählten Magnetoabsorptionsspektren kann der Tensor für die Löcher‐ und Elektronenmassen getrennt angegeben werden, für den Landé‐Faktor nur der kombinierte. Die Löchermassen stimmen mit anderen Meßergebnissen überein. Die Elektronenmassen ergeben sehr kleine Werte.
The orientation distribution function of the crystallites in cold‐rolled and annealed low‐carbon steel sheets
Authors: Bunge H.‐J.
Published: March 2011

The three‐dimensional orientation distribution function of the crystallites in cold‐rolled end annealed low‐carbon steel sheets, which is not directly measurable, has been calculated from pole figures. It consists of a continuous row of orientations together with some ideal orientation components.
A contribution to the problem of the spatial distribution of the spontaneous magnetization in thin films
Authors: Valenta L. , Haubenreisser W. , Brodkorb W.
Published: March 2011

This report summarizes some of the calculations based on the Heisenberg model using the molecular field theory approximation and the Green's function technique. The results are compared with the corresponding ones of other authors. Some consequences are pointed out for the experiment e.g. application of the Mössbauer effect.
Dependence of the ferromagnetic domain width on the thickness of cobalt foils
Authors: Gemperle R. , Gemperle A.
Published: March 2011

Previous measurements of the dependence of the domain width on the crystal thickness of cobalt are extended down to a thickness of 400 Å by means of the Lorentz transmission electron microscopy. In crystals thinner than 4 μm the domain width is proportional to the square root of the thickness as expected for the simple plate domain structure (Kittel type) without surface domain structure. However, the experimental dependence is shifted slightly compared to the theoretical curve.
The ultrasound generation under the gunn effect in a piezoelectric material
Authors: Grinberg A. A. , Kastalskii A. A.
Published: March 2011

A theoretical investigation is made of the possibility of obtaining ultrasound oscillations during the periodic rise and movement of high field domains in the case of the Gunn effect in piezoelectrics. It is shown that for definite correlations between the sound and drift velocity of a domain a resonant ultrasound amplification at frequencies being multiples of the frequency of the current oscillations may be observed. This effect is considered for GaAs.
Effect of temperature on the dielectric relaxation in polycrystalline ferrites
Authors: Haberey F. , Wijn H. P. J.
Published: March 2011

The dielectric constant and the conductivity of polycrystalline ferrites are measured at temperatures between 100 and 400°K and at various frequencies. Different activation energies are obtained for the d.c. and the h.f. conductivity of the samples. Both positive and negative temperature coefficients of the conductivity and the dielectric constant depending on frequency are observed. It is found that the temperature dependence of the dielectric constant is mainly due to the temperature dependence of the conductivities of both types of the Maxwell‐Wagner layers.
Spectres d'absorption et de réflexion, dans l'infrarouge lointain, de ZnSe, ZnTe et CdSe à basse température
Authors: Hadni A. , Claudel J. , Steimer P.
Published: March 2011

Quelques progrès de l'instrumentation dans l'infrarouge lointain ont permis de préciser les constantes optiques de CdSe, ZnTe et ZnSe par des mesures de transmission ou de réflexion à la température de l'hydrogène liquide, de l'azote liquide et à température ordinaire. I. ‐ Les spectres de réflexion d'un polycristal de CdSe, d'une pastille de ZnTe, et d'une lame d'Irtran 4 (ZnSe) obtenus à 290 et 80°K, s'analysent de façon satisfaisante dans l'hypothèse de deux oscillateurs de Lorentz pour CdSe, et d'un seul pour ZnTe, et ZnSe. a) Pour CdSe à 290°K, on trouve ν1 = 171 cm−1, ν2 = 190 cm−1. Seule, la première fréquence est à retenir. La deuxième, bien que nécessaire pour retrouver le spectre de réflexion observé, proviendrait de traces de soufre dans l'échantillon. On en déduit la fréquence longitudinale optique νLO = 214 cm−1, et le rapport de la charge effective des ions à celle de l'électron dans la théorie de Szigetti: e*/e = 0,85. A 80°K, on a ν1 = 175 cm−1 et νLO = 219 cm−1. b) Pour ZnTe à 290°K, on trouve ν1 = 177 cm−1; νLO = 205 cm−1; e*/e = 0,67. A 80°K, ν1 = 181 cm−1; νLO = 209 cm−1. c) Pour ZnSe à 290°K, ν1 = 204 cm−1, νLO = 254 cm−1, e*/e = 0,78. A 80°K, ν1 = 211 cm−1; νLO = 257 cm−1. II. ‐ La transmission d'une couche très mince de ZnSe évaporée sur quartz permet de retrouver ν1 = 204 cm−1 à 290°K, ainsi qu'une valeur approchée du maximum de l'indice d'absorption kmax ≈︁ 5. Par ailleurs, la transmission d'une lame épaisse de ZnSe à la température de l'hydrogène liquide permet de mettre en évidence quatre bandes d'absorption secondaire à 20; 23; 26,8 et 71 μm. La bande très faible à 20 μm est attribuée à une combinaison de trois phonons: LO + TO + TA. Les trois autres bandes sont interprétées par des combinaisons à deux phonons, respectivement: LO + TO, LO + LA et 2 TA. On en déduit: TA = 70,5 cm−1; LA = 149 cm−1; TO = 210 cm−1 et LO = 225 cm−1. On voit que les valeurs de LO et TO à la limite de la zone de Brillouin sont voisines, comme le fait prévoir la valeur de e*/e et la règle de Keyès [24].
Z1‐ and Z2‐centres in mixed crystals of alkali halides doped with Sr++
Authors: Hingsammer J. , Jodl H.
Published: March 2011

In mixed single crystals of KCI‐RbCl: Sr and KCI‐KBr: Sr of various composition grown by the Kyropoulos‐Method Z1‐and Z2‐centres are produced by additive coloration and bleaching. Thus the influence of the substitution of the anions and cations on the spectral position and halfwidth of the Z1‐and 2‐bands can be investigated investigated. In the mixed crystals the spectral position of all absorption bands deviates from the Mollwo relation (v dn = const) in a different manner for anion and cation substitution. The deviations are similar to those found by Smakula for V1‐centres. The halfwidth of all bands in mixed crystals is greater than in pure systems, and the halfwidth of the Z1‐centres increases by ion substitution more than that of the Z2‐centres. The halfwidth of the 1:1 composition of KCl‐RbCl:Sr and KCl‐KBr:Sr is calculated using the model of Gnaedinger and compared with the measured data.
Variation of the refractive indices of calcite, with pressure to 7 kbar
Authors: Davis T. A. , Vedam K.
Published: March 2011

The variation of the ordinary and extraordinary refractive indices of calcite for λ = = 5893 Å with hydrostatic pressure to 7 kbar has been measured from the shift of the localized interference fringes across the sample which was kept in a fluid pressure medium. The change in the thickness of the sample under pressure was considered by utilizing the non‐linear theory of elasticity. The ordinary and the extraordinary refractive indices were found to increase linearly with pressure with slopes of 0.50 × 10−3/kbar and 0.44 × 10−3/kbar respectively in the entire region investigated. The results are compared with the theoretical values evaluated from Bragg's theory, and are also interpreted according to Mueller's theory of photoelasticity.
Elektronenmikroskopie von Gleitlinien auf verformtem NaCl
Authors: Matucha K.‐H.
Published: March 2011

Gleitlinien auf plastisch verformten [001]‐ und [011l‐orientierten NaCl‐Einkristallen werden elektronenmikroskopisch untersucht. Die Abgleitung erfolgt bevorzugt auf zwei zueinander orthogonalen Systemen. In Bereich II der VK werden schräg dazu liegende Dodekaeder‐Systeme mitbetätigt. Bei der [011]‐Orientierung findet zusätzlich Gleitung auf {100}‐Ebenen statt, wodurch die Orientierungsabhängigkeit der VD erklärt werden kann. Bereich III der VK ist durch Quergleiten von Schraubenversetzungen auf . Die Gleitlinien der beiden bevorzugt betätigten Dodekaeder‐Systeme zeigen nach Höhe und Länge eine große Ähnlichkeit mit denen auf für Einfachgleitung orientierten k.f.z. Metallen. Aus den Ergebnissen der Gleitlinienuntersuchungen läßt sich nach Seeger die Steigung der VK in Bereich II berechnen.
Versetzungsecken in Kubisch‐flächenzentrierten Kristallen: Teil I: Die Geometrie der Versetzungsecken
Authors: Differt K.
Published: March 2011

Es werden bisher in der Literatur nicht diskutierte Versetzungskonfigurationen vorgestellt. die in kubisch‐flächenkonzentrierten Kristallen auftreten können. Die Konfigurationen bilden sich an zwei sich treffenden Kantenversetzungen, welche in verschiedenen <110>‐Richtungen verlaufen. Die möglichen Arten dieser Konfigurationen werden zusammengestellt und auf ihre Stabilität untersucht. Bestimmte Arten zeigen einen ausgedehnten Stapelfehler, der zwischen den Kantenversetzungen aufgespannt wird.
Paramagnetic resonance of copper atoms stabilized in alkali‐halide crystals
Authors: Zhitnikov R. A. , Koltsov V. B. , Melnikov N. I.
Published: March 2011

Stabilized copper atoms are obtained at 77°K by irradiating alkali halide crystals (LiCl, NaCl and KCl) containing monovalent copper ions with X‐rays. The properties of these stabilized atoms are studied by PR (paramagnetic resonance). In the paramagnetic resonance spectra a super‐hyperfine structure is observed indicating a substitutional position of the stabilized copper atoms in the cubic lattice of the alkali halide crystals. An interpretation of the data obtained is given.
Time‐of‐flight neutron spectroscopy: a new application of aerodynamic sample levitation
Authors: Kozaily Jad , Hennet Louis , Fischer Henry E. , Koza Marek , Brassamin Séverine , Magazù Salvatore , Kargl Florian
Published: March 2011

A new version of a laser‐heated aerodynamic levitation apparatus that enables the study of high temperature liquids by neutron spectroscopy is presented. This levitator was developed to be used on the IN6 neutron TimeOf‐Flight (TOF) spectrometer at the European High Flux Neutron Source of the Institute Laue Langevin (ILL) in Grenoble, France. This device overcomes earlier restrictions to small sample sizes as routinely used for neutron diffraction studies on levitated liquids at high temperature, and makes other improvements in signal‐to‐noise ratio. A factor of more than three increase in sample volume in combination with the high flux and low background instrument IN6 makes quasielastic neutron scattering (QENS) studies on levitated molten oxides feasible. Here, we present results of a first QENS experiment towards the study of the relaxation dynamics of a molten CaO‐Al2O3 sample. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Oxygen diffusion into GaN from oxygen implanted GaN or Al2O3
Authors: Jakiela Rafal , Dumiszewska Ewa , Caban Piotr , Stonert Anna , Turos Andrzej , Barcz Adam
Published: March 2011

Thermal diffusion and incorporation of oxygen in gallium nitride during MOVPE growth process was investigated using secondary ion mass spectroscopy. The source of oxygen were (18O) implanted into GaN or Al2O3 substrate. Experiment shows no oxygen diffusion from Ar‐implanted sapphire or O‐implanted GaN and extremely deep diffusion from O‐implanted sapphire. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effects of elastic energy on the spinodal decomposition in InAlGaN materials
Authors: Diaz Albarran Salvador F. , Rodriguez Peralta Patricia
Published: March 2011

The purpose of our study is to determine the influence of elastic energy on the spinodal decomposition ranges of InAlGaN alloys lattice‐matched to GaN. The distinction in lattice constants of the binary compounds constituting these alloys gives rise to their deformation energies. Such energies provide the tendency to disintegration that can lead to an appearance of the thermodynamically unstable states with respect to the decomposition. The initial stage of spinodal decomposition of the InAlGaN quaternary alloys is accompanied by transfers of atoms over distances of a lattice parameter. Accordingly, these transfers produce a thin two‐layer region with negligibly small differences in their compositions. Formation of these layers causes the elastic energy. The alloys are represented as quaternary regular solutions. The internal deformation energy is calculated with the interaction parameters estimated by the valence force field model. The spinodal decomposition ranges of these materials are demonstrated up to 580 °C (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Theoretical study on the influence of surface hydrogen coverage on the initial growth process of AlN(0001) surfaces
Authors: Suzuki Hikari , Murakami Hisashi , Kumagai Yoshinao , Koukitu Akinori
Published: March 2011

The adsorption processes of group‐V sources used in metalorganic vapor phase epitaxy (MOVPE) and hydride vapor phase epitaxy (HVPE) were investigated using first‐principle calculations based on the density functional theory (DFT) to understand the initial growth process of AlN(0001). To examine the influence of surface hydrogen coverage on the initial growth process, the ideal surface and a reconstructed surface with an adsorbed 0.75 monolayer of hydrogen were used as the initial surface structures. NH3 and NH2 generated by the decomposition of NH3 were considered as group‐V sources. From the calculations, the influence of surface hydrogen coverage on the initial growth process of AlN(0001) surfaces in vapor phase epitaxy was clarified. It was revealed that surface hydrogen coverage does not have an effect on adsorption of NH3, whereas NH2 was affected by hydrogen on the surface. It was also demonstrated that the adsorption energies for NH3 and NH2 on the ideal and reconstructed GaN(0001) surfaces are smaller than those on the ideal and reconstructed AlN(0001) surfaces (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Measurements of generation‐recombination effect by low‐frequency phase‐noise technique in AlGaN/GaN MOSHFETs
Authors: Kayis Cemil , Leach Jacob H. , Zhu C.Y. , Wu Mo , Li X. , Özgür Ümit , Morkoç Hadis , Yang X. , Misra Veena , Handel Peter H.
Published: March 2011

Generation‐recombination processes in AlGaN/GaN metal‐oxide‐semiconductor heterostructure field‐effect transistors (MOSHFETs) with HfAlO gate dielectric has been investigated through low‐frequency phase‐noise. Some devices tested exhibited noise spectra deviating from the well‐known (1/fγ)spectrum. These devices showed broad peaks attributed to generation‐recombination (GR) in the noise‐spectral‐density vs. frequency plots, which shifted toward higher frequencies at elevated temperatures. The unannealed and annealed MOSHFETs exhibited trap energy values as 0.22 eV and 0.11 eV at drain bias values of 6.3 V and 10 V, respectively. We also monitored the effect of source‐drain bias on the excess GR noise. The time constant of the traps decreased from 16.7 ms to 2.1 ms as we increased the VDS from 10 V to 18 V for the annealed devices. This effect can be explained by the potential barrier lowering (Frenkel‐Poole effect) of the traps by electric field (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Growth of GaN based structures on focused ion beam patterned templates
Authors: Cordier Y. , Tottereau O. , Nguyen L. , Ramdani M. , Soltani A. , Boucherit M. , Troadec D. , Lo F.‐Y. , Hu Y. Y. , Ludwig A. , Wieck A. D.
Published: March 2011

Focused ion beam technique is a powerful tool for defining patterns within a semiconductor film. In this paper, we show that it is possible to realize patterns such as disks and columns within thick GaN templates and that it is compatible with the regrowth of GaN based heterostructures. We study the effect of the pattern size and shape on the regrowth by molecular beam epitaxy. We show that the growth using ammonia as the nitrogen source with flux at temperature optimized for 2‐dimensional growth leads to the apparition of well defined growth planes. We show that the development of these planes is dependent with the initial pattern size and shape. These results confirm the difficulty for realizing micro or nano‐columns with axial heterostructures. At the opposite, these growth conditions seem favourable for core‐shell heterostructures column with well defined m‐plane and eventually a‐plane lateral facets. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the reduction of efficiency loss in polar c ‐plane and non‐polar m ‐plane InGaN light emitting diodes
Authors: Li X. , Ni X. , Liu H. Y. , Zhang F. , Liu S. , Lee J. , Avrutin V. , Özgür Ü. , Paskova T. , Mulholland G. , Evans K. R. , Morkoç H.
Published: March 2011

We have undertaken a series of experiments in InGaN light emitting diode (LED) structures both on polar (c‐plane) and non‐polar (m‐plane) GaN substrates with and without magnesium doped AlGaN electron blocking layers (EBLs) on the p‐side of the p‐n junction to shed the much needed light on the carrier injection and transport. The LEDs grown on c‐plane bulk GaN substrates without EBL show 40% peak electroluminescence (EL) intensity, while the EL peak intensity of the LEDs grown on m‐plane bulk GaN substrates without EBL is 30% of that with EBL. However, optical measurements for internal quantum efficiency (IQE) reveal that the IQE values of LEDs with and without EBL are comparable for both cases, which are in the range of 80‐85% for m‐plane variety and 50% for c‐plane variety. Furthermore, with varying Al composition (15%, 8%, 0%) in the EBL, the EL intensity for both m‐pane and c‐plane LEDs decrease progressively as the Al composition decreases. When highly conductive and transparent Ga doped ZnO layers are used as the current spreading layers for LEDs, the degradation of the efficiency with injection is significantly reduced to 27% compared to LEDs with semitransparent Ni/Au contacts having 50% efficiency degradation up to the same current density ∼3500 A/cm2. This can be due to presumably the reduction in current filamentation or current crowding. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Depth profile of residual strain in free‐standing GaN substrates measured by cross‐sectional micro‐reflectance spectroscopy
Authors: Yamaguchi A. A. , Geng H. Y. , Sunakawa H. , Sumi N. , Yamamoto K. , Usui A.
Published: March 2011

Depth profiles of residual strain in free‐standing GaN substrates have been successfully measured by a novel method employing cross‐sectional micro‐reflectance spectroscopy. This method can precisely measure very small strains (∼0.01%) with micron‐order spatial resolution. In addition, we have established a theoretical framework to calculate the depth profiles of intrinsic strain, which cause the bending of substrates, from the measured residual strain in bending substrates. These methods were applied for hydride vapour phase epitaxy (HVPE)‐grown free‐standing GaN crystals fabricated by two different facet‐initiated epitaxial lateral overgrowth (FIELO) techniques, and it is found that the intrinsic strain can be controlled by the FIELO technique. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
GaN boules grown by high rate HVPE
Authors: Richter E. , Gründer M. , Schineller B. , Brunner F. , Zeimer U. , Netzel C. , Weyers M. , Tränkle G.
Published: March 2011

The most promising approach for GaN substrate fabrication on the base of HVPE consists in the growth of thick GaN crystals and subsequent cutting of these boules into slices followed by conventional surface preparation. This work focusses on a HVPE GaN boule growth process optimized to highest growth rate and the use of a commercially available vertical HVPE reactor from AIXTRON in order to develop a technology of high productivity to enable low‐cost substrates. To this end, GaN crystals up to thicknesses of 6.3 mm have been grown on 2 inch GaN‐on‐sapphire templates produced by MOVPE. The rate in HVPE growth was 450 µm/h and the material properties of the crystals have been evaluated. No degradation of the material quality was found by comparison of structural, optical and transport properties with published data of the state of the art of bulk GaN. Dislocation densities as low as 6x105 cm‐2, high electron mobility of 960 cm2/Vs for a carrier density of 1x1016 cm‐3, low background impurity incorporation of oxygen and silicon, luminescence with well resolved excitonic emission, and a high value of thermal conductivity of 294±44 W/mK were determined. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Patterning of sapphire/GaN substrates
Authors: Suihkonen S. , Ali M. , Svensk O. , Sintonen S. , Sopanen M. , Lipsanen H. , Törmä P. T. , Nevedomsky V. , Bert N.
Published: March 2011

We present the results of sapphire/GaN substrate patterning on GaN film quality and on LED performance. MOVPE was used to grow GaN films on c‐plane sapphire. The films were then patterned with hexagonal holes with various diameters. When regrown with GaN, voids were formed in the sapphire/GaN interface. The void shape could be controlled from nearly vertical to inclined by changing the pattern dimensions. Patterning resulted also in reduced dislocation density of the overgrown GaN film. X‐ray diffraction and transmission electron microscopy results showed that the reduction is due to bending of edge‐type dislocations during the regrowth of the patterned substrate. Standard LEDs were grown on reference and patterned substrates and processed into chips. When grown on a patterned substrate LED chips showed approximately 10% increase in light output when compared to ones grown on a reference sample. The increase was attributed to improved light extraction. More improvement can be expected by optimizing the pattern geometry and the void shape. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Far beyond the classical data models: symbolic data analysis
Authors: Noirhomme‐Fraiture Monique , Brito Paula
Published: March 2011

This paper introduces symbolic data analysis, explaining how it extends the classical data models to take into account more complete and complex information. Several examples motivate the approach, before the modeling of variables assuming new types of realizations are formally presented. Some methods for the (multivariate) analysis of symbolic data are presented and discussed. This is however far from being exhaustive, given the present dynamic development of this new field of research. © 2011 Wiley Periodicals, Inc. Statistical Analysis and Data Mining 4: 157–170, 2011
Sustainable energy transformations in India under climate policy
Authors: Shukla Priyadarshi R. , Chaturvedi Vaibhav
Published: March 2011

The paper uses an integrated assessment model, GCAM, to analyze two emission stabilization approaches for India – a conventional approach relying on carbon price to typically influence fuel switch and carbon capture and storage responses, and a sustainability approach that aims to conserve resources and deliver multiple dividends. An important feature of the sustainability approach is the focus on national policies to push solar and wind technologies. The paper concludes that sustainability push at a global level for renewable energy technologies is essential together with coordinated national policies and actions, if the 2 °C target is to be achieved with lower global welfare losses. Copyright © 2011 John Wiley & Sons, Ltd and ERP Environment.
Building Personal and Professional Resources of Resilience and Agility in the Healthcare Workplace
Authors: Pipe Teresa Britt , Buchda Vicki L. , Launder Susan , Hudak Barb , Hulvey Lynne , Karns Katherine E. , Pendergast Debra
Published: March 2011

This article describes the rationale, implementation and results of a pilot study evaluating the personal and organizational impact of an educational intervention on the stress of health team members. The compelling imperative for the project was to find a positive and effective way to address the documented stress levels of healthcare workers.

Pilot study of oncology staff (n = 29) and healthcare leaders (n = 15) exploring the impact of a positive coping approach on Personal and Organizational Quality Assessment‐Revised (POQA‐R) scores at baseline and 7 months using paired t‐tests.

Personal and organizational indicators of stress decreased in the expected directions in both groups over the time intervals. The majority of POQA‐R categories were statistically significantly improved in the oncology staff, and many of the categories were statistically significantly improved in the leadership group.

The findings from this project demonstrate that stress and its symptoms are problematic issues for hospital and ambulatory clinic staff as evidenced by baseline measures of distress. Further, a workplace intervention was feasible and effective in promoting positive strategies for coping and enhancing well‐being, personally and organizationally. Copyright © 2011 John Wiley & Sons, Ltd.
When do strategic alliances inhibit innovation by firms? Evidence from patent pools in the global optical disc industry
Authors: Joshi Amol M. , Nerkar Atul
Published: March 2011

Research and development (R&D) consortia are specialized strategic alliances that shape the direction and scope of firm innovation activities. Little research exists on the performance consequences of participating in R&D consortia. We study the effect of patent pools, a unique form of R&D consortia, on firm performance in innovation. While prior research on alliances generally implies that patent pools enhance firm innovation, our study finds the opposite. Analyzing data on systemic innovation in the global optical disc industry, we find that patent pool formation substantially and significantly decreases both the quantity and quality of patents subsequently generated by licensors and licensees relative to the patenting activity of nonparticipants. Our empirical findings suggest that patent pools actually inhibit, rather than enhance, systemic innovation by participating firms. Copyright © 2011 John Wiley & Sons, Ltd.
Wear Protection by Fe‐B‐C Hard Phases
Authors: Berns Hans , Saltykova Anastasia , Röttger Arne , Heger Dietrich
Published: March 2011

Four as‐cast iron alloys with (mass%) 1B + 3C, 2B + 2C, 3B + 1C and 4B + 1C were investigated in respect to their microstructure by optical and scanning electron microscopy with EDX and ESBD and by microprobe analysis. The microhardness of eutectic Fe3(C,B) increased with the B/C ratio and raised the resistance to scratching by Flint particles. The low melting range of the castings was used for the powder metallurgical production of a metal matrix composite by liquid phase sintering of admixed hard particles in an Fe‐B‐C base material. Abrasive wear tests showed that the eutectic carborides in the base material raised the wear resistance even more than the admixed particles.
Relationship between SLC6A3 genotype and striatal dopamine transporter availability: A meta‐analysis of human single photon emission computed tomography studies
Authors: Costa Anna , Riedel Michael , Müller Ulrich , Möller Hans‐Jürge , Ettinger Ulrich
Published: March 2011

The human dopamine transporter (DAT) gene (SLC6A3) contains a 40‐bp variable number of tandem repeats (VNTR) polymorphism. A number of studies have investigated the association of this VNTR with striatal DAT availability in humans using single photon emission computed tomography (SPECT). However, the results are not consistent. Therefore, we carried out a meta‐analysis of the association between the SLC6A3 VNTR and striatal DAT binding measured in human SPECT studies. The meta‐analysis of five samples of healthy individuals failed to find a significant difference in DAT availability between SLC6A3 9‐repeat carriers and 10‐repeat homozygotes (P = 0.22) although the 9R carriers had nominally higher striatal DAT levels (g = 0.66). The results remained nonsignificant after the inclusion of patient samples, namely schizophrenia, attention deficit hyperactivity disorder, and Parkinson's disease (four samples; all P > 0.18). To conclude, this meta‐analysis provides no evidence to support the hypothesis that the SLC6A3 VNTR is significantly associated with interindividual differences in DAT availability in the human striatum. Further work is needed to clarify the molecular mechanisms by which this polymorphism may affect cognition and psychiatric disorders, if not through altered expression as measured by molecular imaging. Synapse, 2011. © 2011 Wiley‐Liss, Inc.
Downregulation of gephyrin in temporal lobe epilepsy neurons in humans and a rat model
Authors: Fang Min , Shen Lan , Yin Huan , Pan Yu‐Min , Wang Liang , Chen Dan , Xi Zhi‐Qin , Xiao Zheng , Wang Xue‐Feng , Zhou Sheng‐Nian
Published: March 2011

Gephyrin, which is a postsynaptic scaffolding protein participated in clustering GABAA receptors at inhibitory synapses, has been reported to be involved in temporal lobe epilepsy (TLE) recently. Here, we investigate gephyrin protein expression in the temporal lobe epileptic foci in epileptic patients and experimental animals in order to explore the probable relationship between gephyrin expression and TLE. Using immunohistochemistry, immunofluorescence, and western blot analysis, gephyrin expression was examined in 30 human temporal neocortex samples from patients who underwent surgery to treat drug‐refractory TLE and 10 histological normal temporal neocortex from the controls. Meanwhile, we investigated the gephyrin expression in the hippocampus and adjacent neocortex from experimental rats on 24 h, 48 h, 1 week, 2 weeks, 1 month, and 2 months postseizure and from control rats. Gephyrin protein was mainly expressed in the membrane and cytoplasm of neurons in temporal lobe epileptic foci in humans and experimental rats. Gephyrin expression was significantly lower in the temporal neocortex of TLE patients compared to the controls. In experimental rats, the expression of gephyrin in temporal lobe was downregulated in epileptic groups compared to the control group. Gephyrin expression gradually decreased during the acute period and the latent period, but then began to increase below the levels seen in controls during the chronic phase. Our findings suggest that gephyrin may be involved in the development of TLE. Synapse, 2011. © 2011 Wiley‐Liss, Inc.
Development of lateral displacement sensor for real‐time detection of structural damage
Authors: Matsuya Iwao , Tomishi Ryota , Sato Maya , Kanekawa Kiyoshi , Nitta Yoshihiro , Takahashi Motoichi , Miura Satoru , Suzuki Yasutsugu , Hatada Tomohiko , Katamura Ryuta , Tanii Takashi , Shoji Shuichi , Nishitani Akira , Ohdomari Iwao
Published: March 2011

We have developed a novel sensor that enables us to measure the relative story displacement of a building structure in real time. This lateral displacement sensor (LDS) is composed of a light‐emitting diode (LED) array, which is fixed on the ceiling, and a position‐sensitive detector (PSD) unit, which is placed on the floor. We optimized the LDS to achieve high accuracy in lateral displacement measurement. The accuracy was evaluated to be 60 µm by conducting shaking table tests. Two LDSs were implemented in an actual building equipped with an active variable stiffness (AVS) system, and the building was vibrated with seismic waveforms by an exciter placed on the rooftop. The seismic displacement of the second floor relative to the first floor was measured using the LDS. Furthermore, the inclination angle of the second floor could be measured using the LDS during the seismic vibration. Using the AVS system, we realized the residual displacement of the second floor without inducing damage to the building, and succeeded in real‐time residual displacement measurement for the first time. These results indicate that the LDS is useful for the health diagnosis of a building structure. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
Real‐time word lip reading system based on trajectory feature
Authors: Saitoh Takeshi , Konishi Ryosuke
Published: March 2011

This paper describes a real‐time word lip reading system. Although our system is based on a word lip reading method already proposed, this system adapts to the user facial movements that cannot be avoided in a real‐time process. With nine subjects, we obtained an average recognition rate of 89% for 14 Japanese words. Moreover, we carried out additional experiments with the system under various conditions, and verified the robustness and usefulness of our system. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
Pattern classification using functional magnetic resonance imaging
Authors: Samuel Schwarzkopf Dietrich , Rees Geraint
Published: March 2011

Over the past decade, pattern classification methods have become widespread in functional magnetic resonance imaging (fMRI). These methods, typically referred to as multivoxel pattern analysis (MVPA) or multivariate pattern decoding, are now applied to a wide range of neuroscientific questions. There has been particular interest in applying these approaches, e.g., in detecting deception or for diagnostic purposes. In this review, we will focus on what can be achieved by pattern classification analyses of fMRI data; the strengths and weaknesses of this approach; and the biological processes giving rise to the signals measured by this method. Finally, we will discuss how these multivariate approaches are starting to be applied to the analysis of anatomical magnetic resonance imaging (MRI) and magnetoencephalographic (MEG) data. WIREs Cogni Sci 2011 2 568–579 DOI: 10.1002/wcs.141

This article is categorized under:

Neuroscience > Cognition
Single‐molecule direct RNA sequencing without cDNA synthesis
Authors: Ozsolak Fatih , Milos Patrice M.
Published: March 2011

Methods for in‐depth genome‐wide characterization of transcriptomes and quantification of transcript levels using various microarray and next‐generation sequencing technologies have emerged as valuable tools for understanding cellular physiology and human disease biology and have begun to be utilized in various clinical diagnostic applications. Current methods, however, typically require RNA to be converted to complementary DNA prior to measurements. This step has been shown to introduce many biases and artifacts. In order to best characterize the ‘true’ transcriptome, the single‐molecule direct RNA sequencing (DRS) technology was developed. This review focuses on the underlying principles behind the DRS, sample preparation steps, and the current and novel avenues of research and applications DRS offers. WIREs RNA 2011 2 565–570 DOI: 10.1002/wrna.84

This article is categorized under:

RNA Processing > 3' End Processing

RNA Methods > RNA Analyses In Vitro and In Silico
The reproductive endocrinology and behavior of Vancouver Island marmot (Marmota vancouverensis)
Authors: Keeley T. , Goodrowe K.L. , Graham L. , Howell C. , MacDonald S.E.
Published: March 2011

The Vancouver Island marmot (Marmota vancouverensis; VIM) is one of North America's most endangered species with fewer than 150 individuals remaining in the wild. A captive breeding program was established across four facilities in Canada as an insurance population and source of animals for reintroduction to the wild. The purpose of this study was to gather information about the basic reproductive biology and behavior of this species, which is essential to improve captive breeding programs. Regular fecal samples were obtained from adult female (n = 14) and male (n = 10) marmots, 2 years of age and older, over 1–3 breeding seasons (2–3 months duration posthibernation) for steroid hormone analysis. Enzyme immunoassays were validated for quantifying fecal testosterone metabolite concentrations for males, and fecal estrogen and progesterone metabolite concentrations for females. Results indicated that fecal progesterone metabolite concentrations can be used to monitor ovulation and pregnancy. Behavioral monitoring through infrared video surveillance was conducted in four breeding pairs over a 2‐year period (n = 7 behavioral profiles). Breeding behaviors correlated strongly with changes in reproductive endocrine profiles. A high frequency of play behavior or “wrestling” was observed in conjunction with breeding activity before an elevation in progesterone metabolite concentrations. Impending parturition was associated with increased aggression and exclusion of the male from the maternal nestbox as well as an increase in nesting activity. Observational data combined with hormonal analysis suggest that female VIMs are induced ovulators and that multiple breeding attempts may be required for ovulation and conception. Gestation appears to be approximately 34 days from peak breeding activity (32 days from estimated ovulation). Fecal testosterone concentrations suggest that testicular activity is seasonal with the reproductive activity occurring immediately posthibernation. Monitoring breeding behavior is a useful means of indicating estrus, conception and pregnancy, which can also be supported by the hormonal analysis of daily fecal samples of individual animals. Zoo Biol 31:275–290, 2012. © 2011 Wiley Periodicals, Inc.
Information gain of black-box testing
Authors: Yang Linmin , Dang Zhe , Fischer Thomas R.
Published: March 2011

For model-based black-box testing, test cases are often selected from the syntactic appearance of the specification of the system under test, according to a pre-given test data adequacy criterion. We introduce a novel approach that is semantics-based, independent of the syntactic appearance of the system specification. Basically, we model the system under test as a random variable, whose sample space consists of all possible behavior sets (with respect to the specification) over the known interface of the black-box. The entropy of the system is measured as the (Shannon) entropy of the random variable. In our criterion, the coverage of a test set is measured as the expected amount of entropy decrease (i.e. the expected amount of information gained) once the test set is run. Since our criterion is syntactic independent, we study the notion of information-optimal software testing where, within a given constraint, a test set is selected to gain the most information.
Integrating Cultural Community Psychology: Activity Settings and the Shared Meanings of Intersubjectivity
Authors: O'Donnell Clifford R. , Tharp Roland G.
Published: March 2011

Cultural and community psychology share a common emphasis on context, yet their leading journals rarely cite each other's articles. Greater integration of the concepts of culture and community within and across their disciplines would enrich and facilitate the viability of cultural community psychology. The contextual theory of activity settings is proposed as one means to integrate the concepts of culture and community in cultural community psychology. Through shared activities, participants develop common experiences that affect their psychological being, including their cognitions, emotions, and behavioral development. The psychological result of these experiences is intersubjectivity. Culture is defined as the shared meanings that people develop through their common historic, linguistic, social, economic, and political experiences. The shared meanings of culture arise through the intersubjectivity developed in activity settings. Cultural community psychology presents formidable epistemological challenges, but overcoming these challenges could contribute to the transformation and advancement of community psychology.
Assessment of the potential of a boron–fructose additive in counteracting the toxic effect of Fusarium mycotoxins
Authors: Taranu Ionelia , Marin Daniela E. , Manda Gina , Motiu Monica , Neagoe Ionela , Tabuc Cristina , Stancu Mariana , Olteanu Margareta
Published: March 2011

Trichotecenes are mycotoxins produced by Fusarium sp., which may contaminate animal feeds and human food. A feeding trial was conducted to evaluate the effect of a fusarotoxin-contaminated diet, and to explore the counteracting potential of a calcium fructoborate (CFrB) additive on performance, typical health biochemistry parameters and immune response in weaned pigs. A naturally contaminated maize, containing low doses of deoxynivalenol, zearalenone, fumonisins and T-2/HT-2 toxins (1790, 20, 0·6 and 90 parts per billion), was included in a maize–soyabean meal diet, and given ad libitum to eight weaned piglets (two groups: four pigs/group) for a period of 24 d. CFrB was administered to one of the contaminated groups and to another four piglets as a daily supplement, following the manufacturer's recommendation. A decrease in performance was observed in contaminated animals at this concentration of feed toxins, which was ameliorated by the dietary CFrB supplementation. Fusarium toxins also altered the pig immune response by increasing (P < 0·05) the ex vivo peripheral blood mononuclear cell proliferation (111·7 % in comparison with control), the respiratory burst of porcine granulocytes (15·4 % for responsive cells v. 5·1 % for unstimulated cells and 70·95 v. 22·65 % for stimulated cells, respectively), the percentage of peripheral T, CD3+, CD3+CD4+ and CD3+CD8+ subsets and the synthesis of IL-1β, TNF-α and IL-8 (123·8, 217·1 and 255·1 %, respectively). The diet containing the CFrB additive reduced these exacerbated cellular immune responses induced by Fusarium toxins. However, consumption of CFrB did not counteract the effect of mycotoxins on biochemistry parameters, and increased plasma IgM and IgG of contaminated pigs.
Experimental measurement of large-scale three-dimensional structures in a turbulent boundary layer. Part 1. Vortex packets
Authors: DENNIS DAVID J. C. , NICKELS TIMOTHY B.
Published: March 2011

Experimental measurements of the three-dimensional (3D) velocity field in a moderate Reynolds number zero pressure-gradient boundary layer are presented. The measurements are analysed to produce 3D correlations and conditional averaging techniques are used to further elucidate the underlying structure. The results show clear evidence of vortex-packet-type structures and shed new light on the detailed 3D structure of such packets in a real zero pressure-gradient boundary layer.
Experimental measurement of large-scale three-dimensional structures in a turbulent boundary layer. Part 2. Long structures
Authors: DENNIS DAVID J. C. , NICKELS TIMOTHY B.
Published: March 2011

Three-dimensional (3D) measurements of a turbulent boundary layer have been made using high-speed particle image velocimetry (PIV) coupled with Taylor's hypothesis, with the objective of characterising the very long streamwise structures that have been observed previously. The measurements show the 3D character of both low- and high-speed structures over very long volumes. The statistics of these structures are considered, as is their relationship to the important turbulence quantities. In particular, the length of the structures and their wall-normal extent have been considered and their relationship to the other components of the velocity fluctuations and the instantaneous stress.
Geometry of valley growth
Authors: PETROFF A. P. , DEVAUCHELLE O. , ABRAMS D. M. , LOBKOVSKY A. E. , KUDROLLI A. , ROTHMAN D. H.
Published: March 2011

Although amphitheatre-shaped valley heads can be cut by groundwater flows emerging from springs, recent geological evidence suggests that other processes may also produce similar features, thus confounding the interpretations of such valley heads on Earth and Mars. To better understand the origin of this topographic form, we combine field observations, laboratory experiments, analysis of a high-resolution topographic map and mathematical theory to quantitatively characterize a class of physical phenomena that produce amphitheatre-shaped heads. The resulting geometric growth equation accurately predicts the shape of decimetre-wide channels in laboratory experiments, 100 m-wide valleys in Florida and Idaho, and kilometre-wide valleys on Mars. We find that, whenever the processes shaping a landscape favour the growth of sharply protruding features, channels develop amphitheatre-shaped heads with an aspect ratio of π.