bluuebunny/crossref_metadata_2025 huggingface dataset:
Testgütekriterien des Fragebogens VKS zur Erfassung volitionaler Komponenten im Sport
Authors: Wenhold Franziska , Elbe Anne-Marie , Beckmann Jürgen
Published: July 2009

Zusammenfassung. In diesem Beitrag wird der Fragebogen zur Erfassung Volitionaler Komponenten im Sport (VKS) hinsichtlich seiner Testgütekriterien überprüft. Nach einer Itemanalyse erfolgte eine Faktorenanalyse, entlang welcher sich die vier Faktoren Selbstoptimierung, Aktivierungsmangel, Fokusverlust und Selbstblockierung extrahieren ließen. Der Fragebogen besitzt zudem zufriedenstellende Skalenhomogenität (Cronbachs Alpha) und Retestreliabilität. Die externe Konstruktvalidität zeigt sich durch theoriekonforme ( Kuhl, 2001 ) Zusammenhänge mit dem allgemeinen Verfahren VCQ II ( Kuhl & Fuhrmann, 1998 ) sowie der Handlungsorientierung im Sport gemessen mit dem HOSP ( Beckmann, 2003 ). Weiterhin kann die Kriteriumsvalidität anhand eines Expertenurteils (Trainereinschätzung) nachgewiesen werden. Überdies sind Unterschiede zwischen leistungsstärkeren und leistungsschwächeren Athleten über den Fragebogen VKS erkennbar.
Altersbedingte Veränderung differentieller Merkmale
Authors: Mussel Patrick , von der Bruck Heike , Schuler Heinz
Published: July 2009

Zusammenfassung. Die vorliegende Studie untersuchte je sieben kognitive Merkmale und Temperamentsmerkmale auf Mittelwertsunterschiede zwischen einer Gruppe von über 50-jährigen im Vergleich zu einer Gruppe von unter 25-jährigen arbeitslosen Personen. In Einklang mit den Annahmen des Differenzmodells ( Baltes, 1997 ) zeigten sich dabei für ältere Personen sowohl Defizite (insbesondere verringerte allgemeine und spezifische kognitive Fähigkeiten) als auch Ressourcen (insbesondere höhere interpersonelle Fähigkeiten, Integrität und Leistungsmotivation). Diese Veränderungen wurden in Bezug auf ihre Bedeutsamkeit für externe Kriterien beruflichen Erfolgs weiter untersucht. Als Kriterium diente dabei die Wahrscheinlichkeit eines beruflichen Wiedereinstiegs, der durch die oben genannten Persönlichkeitsmerkmale vorhergesagt werden konnte. Kern der vorliegenden Studie ist die konzeptionelle und empirische Verknüpfung von Alterseffekten und Kriterien des beruflichen Wiedereinstiegs. Sich hieraus ergebende theoretische und praktische Implikationen werden diskutiert.
Entwicklung und Prüfungeines Modells zur Förderungvon Intrapreneurshipin der dualen Berufsausbildung
Authors: Korunka Christian , Frank Hermann , Lueger Manfred , Ebner Markus
Published: July 2009

Zusammenfassung. Die vorliegende Arbeit legt einen Vorschlag zur Erfassung von Intrapreneurship-Kompetenz in der dualen Berufsausbildung vor. Dafür wird ein Rahmenmodell zur Förderung von Intrapreneurship entwickelt und empirisch in einer repräsentativen Querschnittsstudie überprüft. „Intrapreneurship” wird als ein Zusammenwirken von personalen und fachlich-methodischen Kompetenzen bestimmt, die von den Bereichen Umwelt, Ausbildungskontext und Ausbildungsprozess beeinflusst werden können. Regressionsanalytische Auswertungen zeigen, dass die aufgeklärte Varianz bei den fachlich-methodischen Kompetenzen höher ist als bei den intrapreneurspezifischen personalen Kompetenzen. Zusätzlich wird untersucht, ob spätere Berufspläne in Richtung Intra- bzw. Entrepreneurship auf der Basis des Modells vorhergesagt werden können. Diesbezüglich machen die Ergebnisse deutlich, dass sowohl Intra- als auch Entrepreneur/innen über ein erhöhtes Ausmaß an intrapreneurspezifischen Kompetenzen verfügen, jedoch Intrapreneur/innen mit wesentlichen betrieblichen Aspekten überdurchschnittlich zufrieden sind, während sich Entrepreneur/innen durch Rollenvorbilder sowie einer tendenziellen Unzufriedenheit mit spezifischen Ausbildungsbereichen auszeichnen.
A model for the termination of the Ryukyu subduction zone against Taiwan: A junction of collision, subduction/separation, and subduction boundaries
Authors: Wu Francis T. , Liang Wen‐Tzong , Lee Jian‐Cheng , Benz Harley , Villasenor Antonio
Published: July 2009

The NW moving Philippine Sea plate (PSP) collides with the Eurasian plate (EUP) in the vicinity of Taiwan, and at the same time, it subducts toward the north along SW Ryukyu. The Ryukyu subduction zone terminates against eastern Taiwan. While the Ryukyu Trench is a linear bathymetric low about 100 km east of Taiwan, closer to Taiwan, it cannot be clearly identified bathymetrically owing to the deformation related to the collision, making the location of the intersection of the Ryukyu with Taiwan difficult to decipher. We propose a model for this complex of boundaries on the basis of seismicity and 3‐D velocity structures. In this model the intersection is placed at the latitude of about 23.7°N, placing the northern part of the Coastal Range on EUP. As PSP gets deeper along the subduction zone it collides with EUP on the Taiwan side only where they are in direct contact. Thus, the Eurasian plate on the Taiwan side is being pushed and compressed by the NW moving Philippine Sea plate, at increasing depth toward the north. Offshore of northeastern Taiwan the wedge‐shaped EUP on top of the Ryukyu subducting plate is connected to the EUP on the Ryukyu side and coupled to the NW moving PSP by friction at the plate interface. The two sides of the EUP above the western end of the subduction zone are not subjected to the same forces, and a difference in motions can be expected. The deformation of Taiwan as revealed by continuous GPS measurements, geodetic movement along the east coast of Taiwan, and the formation of the Hoping Basin can be understood in terms of the proposed model.
Time‐dependent brittle creep in Darley Dale sandstone
Authors: Heap M. J. , Baud P. , Meredith P. G. , Bell A. F. , Main I. G.
Published: July 2009

The characterization of time‐dependent brittle rock deformation is fundamental to understanding the long‐term evolution and dynamics of the Earth's crust. The chemical influence of pore water promotes time‐dependent deformation through stress corrosion cracking that allows rocks to deform at stresses far below their short‐term failure strength. Here, we report results from a study of time‐dependent brittle creep in water‐saturated samples of Darley Dale sandstone (initial porosity, 13%) under triaxial stress conditions. Results from conventional creep experiments show that axial strain rate is heavily dependent on the applied differential stress. A reduction of only 10% in differential stress results in a decrease in strain rate of more than two orders of magnitude. However, natural sample variability means that multiple experiments must be performed to yield consistent results. Hence we also demonstrate that the use of stress‐stepping creep experiments can successfully overcome this issue. We have used the stress‐stepping technique to investigate the influence of confining pressure at effective confining pressures of 10, 30, and 50 MPa (while maintaining a constant 20 MPa pore fluid pressure). Our results demonstrate that the stress corrosion process appears to be significantly inhibited at higher effective pressures, with the creep strain rate reduced by multiple orders of magnitude. The influence of doubling the pore fluid pressure, however, while maintaining a constant effective confining pressure, is shown to influence the rate of stress corrosion within the range expected from sample variability. We discuss these results in the context of microstructural analysis, acoustic emission hypocenter locations, and fits to proposed macroscopic creep laws.
“Hook” structure in MARSIS ionogram and its interpretation
Authors: Wang X.‐D. , Wang J.‐S. , Nielsen E. , Zou H.
Published: July 2009

MARSIS/MEX is a low frequency radar used to sound the ionosphere of Mars. In general the echo trace associated with reflections in nadir indicates an ionosphere with a main maximum electron density at typically about 130 km altitude, and a monotonously decreasing density with increasing altitude. Another maximum is sometimes detected at higher altitudes, indicating a double layer in the upper ionosphere. Sometimes a special structure (here called a “hook”) is observed at the low frequency end of the trace: as the sounding frequency decreases the delay time of sounding signal increases rapidly. It is here proposed that this signature indicates a secondary maximum with density which is so low that it can be only partly resolved by the radar. An analytical inversion approach coping with the “hook” case is then proposed. It is further suggested that the “hook” is caused by vertical wavelike structures in the Martian topside ionosphere.
Exactly solvable quantum Sturm–Liouville problems
Authors: Büyükaşık Şirin A. , Pashaev Oktay K. , Tigrak-Ulaş Esra
Published: July 2009

The harmonic oscillator with time-dependent parameters covers a broad spectrum of physical problems from quantum transport, quantum optics, and quantum information to cosmology. Several methods have been developed to quantize this fundamental system, such as the path integral method, the Lewis–Riesenfeld time invariant method, the evolution operator or dynamical symmetry method, etc. In all these methods, solution of the quantum problem is given in terms of the classical one. However, only few exactly solvable problems of the last one, such as the damped oscillator or the Caldirola–Kanai model, have been treated. The goal of the present paper is to introduce a wide class of exactly solvable quantum models in terms of the Sturm–Liouville problem for classical orthogonal polynomials. This allows us to solve exactly the corresponding quantum parametric oscillators with specific damping and frequency dependence, which can be considered as quantum Sturm–Liouville problems.
Determination of local minority carrier diffusion lengths in crystalline silicon from luminescence images
Authors: Giesecke J. A. , Kasemann M. , Warta W.
Published: July 2009

In 2007 Würfel et al. [J. Appl. Phys. 101, 123110 (2007)] introduced a method to determine spatially resolved minority carrier diffusion lengths in silicon solar cells from electroluminescence intensity ratios. The key feature of this method was the exploitation of reabsorption of luminescence within a solar cell through optical short pass filters. The first part of this work deals with some experimental challenges which we encountered with the practical application of this method. A procedure of removing an artifact due to typical lateral filter inhomogeneities is introduced. Moreover, temperature dependence of luminescence is discussed and incorporated into the underlying model. The second part of this work aims at a determination of spatially resolved carrier diffusion lengths from photoluminescence (PL) on silicon wafers. The shortcomings of a diffusion length determination from PL intensity ratios are discussed. A straightforward method to determine spatially resolved integral excess charge carrier density from single PL images is introduced, thereby rendering a calibration with another measuring technique unnecessary. We show that quantitative information about recombination properties, such as minority carrier diffusion length, can be directly extracted from single PL images of silicon wafers.
Symmetry-based dipolar recoupling by optimal control: Band-selective experiments for assignment of solid-state NMR spectra of proteins
Authors: Nielsen Anders Bodholt , Bjerring Morten , Nielsen Jakob Toudahl , Nielsen Niels Chr.
Published: July 2009

We present design of novel low-power homonuclear dipolar recoupling experiments for magic-angle-spinning solid-state NMR studies of proteins. The pulse sequences are developed by combining principles of symmetry-based dipolar recoupling and optimal control-based pulse sequence design. The scaffold of the pulse sequences is formed by known CN-type recoupling sequences, while the intrinsic sequence elements are designed using optimal control. This procedure allows for the development of high-performance pulse sequences demanding significantly weaker rf fields than previous symmetry-based pulse sequences while compensating for rf inhomogeneity and providing excitation over relevant ranges of chemical shifts for biological applications. The new recoupling experiments, referred to as optimal control CN (COCN), are demonstrated numerically and experimentally by two-dimensional (2D) C13–C13 and three-dimensional (3D) N15–C13–C13 chemical shift correlation experiments on uniformly C13, N15-labeled ubiquitin. Exploiting the double-quantum, band-selective dipolar recoupling properties of the COCN experiments, we demonstrate significant sensitivity enhancement for 2D and 3D correlation spectra showing exclusively one- or two-bond correlations.
Prediction of energetically optimal single-walled carbon nanotubes for hydrogen physisorption
Authors: Fan W. J. , Zhang R. Q. , Teo Boon K. , Aradi B. , Frauenheim Th.
Published: July 2009

Hydrogen storage by carbon nanotubes (CNTs) is a challenging issue still in debate. Using an approximate density functional method augmented with a van der Waals dispersion term, we have shown that there are binding maxima for H2/single-walled carbon nanotube (SWCNT) complexes at (5, 5) and (8, 0) tubes for armchair and zigzag CNTs, respectively, with binding energies around three times as large as that of H2 on graphene surface. We predict that SWCNTs with diameters of 6–7 Å are energetically optimal candidates for physisorption of molecular hydrogen.
Effects of disorder in a photonic crystal on the extraction efficiency of a light-emitting diode
Authors: Wang Bowen , Jin Yi , He Sailing
Published: July 2009

We analyze the effects of disorder in a photonic crystal (PC) on the extraction efficiency of a light-emitting diode (LED) by using a full-vectorial finite-difference time-domain method. The extraction efficiency of the ordered PC LED (EEOPL) and the extraction efficiency of the disordered PC LED (EEDPL) are compared. The physical explanation for the difference between the EEOPL and EEDPL is given through the mechanism of the guided modes and leaky modes. When the frequencies are in the leaky mode region, the EEOPL and EEDPL are comparable even if some disorder exists in the fabrication process.
Electrical properties of GaN/poly(3-hexylthiophene) interfaces
Authors: Park B.-N. , Uhlrich J. J. , Kuech T. F. , Evans P. G.
Published: July 2009

Interfaces between wide-bandgap semiconductors and polymeric electronic materials are model systems for geometrically more complicated interfaces formed in nanostructured composite electronic, photonic, and photovoltaic devices. The wide-bandgap semiconductor GaN is readily available with well-defined electronic and structural properties, including reproducible control of doping and conductivity type, and can ideally serve as the inorganic side of the model system. Electron transport through a GaN/poly(3-hexylthiophene) (P3HT) semiconductor heterojunction depends on the conductivity type of the GaN and on the doping level in the polymer. The total contact resistance of a planar P3HT film with GaN contacts in a symmetric p-GaN/P3HT/p-GaN structure is consistent with the contribution of reversed-biased junction at one of the GaN/P3HT interfaces. An n-GaN/P3HT/n-GaN structure has a lower total resistance than the p-GaN structure, possibly arising from band-to-band tunneling at the interface. Doping the P3HT layer with iodine greatly reduced the contact resistance for interfaces with both conductivity types of GaN.
Electrostrictive energy conversion in polyurethane nanocomposites
Authors: Guyomar D. , Lebrun L. , Putson C. , Cottinet P.-J. , Guiffard B. , Muensit S.
Published: July 2009

Electrostrictive polymers have demonstrated an ability to convert mechanical energy into electrical energy and vice versa. This energy conversion has been exploited in an extensive range of applications, including sensors and actuators. Recently, electrostrictive polymers have been investigated as electroactive materials for energy harvesting. The present work aims at establishing an analytical modeling based on electrostrictive equations for predicting a current that can be obtained from the first flexural mode of a beam which was attached by the electrostrictive polymers. The study was carried out on polyurethane films, either without filler or filled with nanosized SiC or a carbon nanopowder. Experimental measurements of the harvested current have been compared to the theoretical behavior predicted by the proposed model. A good agreement was observed between the two sets of data, which consequently validated that the modeling can be used to optimize the choice of materials. It was also shown that the incorporation of nanofillers in polyurethane increased the obtained current.
PoDFluX: A new Monte Carlo ray-tracing model for powder diffraction and fluorescence
Authors: Hansford Graeme M.
Published: July 2009

PoDFluX is a new Monte Carlo ray-tracing program that simulates from first principles x-ray powder diffraction from crystalline materials and x-ray fluorescence from materials with a defined elemental composition. This model has been written primarily for the optimization of miniaturized planetary x-ray diffraction instrumentation but wider applications are certainly possible. A particular strength of the model is the implementation of several variance-reduction techniques for the minimization of execution times. Comparisons of model output with experimental diffraction and fluorescence data show good quantitative agreement.
Electronic structure and optical absorption of the Bi4Ge3O12 and the Bi4Si3O12 scintillators in ultraviolet region: An ab initio study
Authors: Lima A. F. , Souza S. O. , Lalić M. V.
Published: July 2009

Ab initio calculations based on density-functional theory have been employed to study structural and electronic properties of Bi4Ge3O12 (BGO) and Bi4Si3O12 (BSO), as well as their optical characteristics in ultraviolet region, up to 40 eV. The electronic structure around the band gap is found to be similar in both compounds, dominated by the O p- and the Bi s-states (valence band top) and the Bi p-states (conduction band bottom). The gap is found to be indirect in both BGO and BSO. The optical spectra are analyzed, compared, and interpreted in terms of calculated band structures. It is shown that the absorption process involves significant energy flow from the O ions to the Bi ions. This fact stresses importance of the first neighborhood of the Bi (six O’s forming an octahedron), which is more distorted in the BSO than in the BGO. The latter difference is mainly responsible for the different absorption characteristics of the BGO and BSO.
Angular distribution of atoms ejected by laser ablation of different metals
Authors: Konomi I. , Motohiro T. , Asaoka T.
Published: July 2009

Angular distributions of 13 different metals ejected by laser ablation using fourth harmonics (wavelength=266 nm) of neodymium doped yttrium aluminum garnet laser and a fluence close to near-threshold value (2.3 J/cm2) have been investigated with a high angular resolution. The angular distribution which is characterized by the exponent n of cosn θ distribution showed very broad range of values between 3 and 24 for different metals. A simple relation that the exponent n is proportional to the square root of particle atomic weight as reported previously has not been observed. Instead, a general trend has been found that the metals with higher sublimation energy such as Ta and Zr show narrower angular distribution than those with lower sublimation energy such as Sn and In. While the sublimation energy of metals has a great influence on the angular distribution of ejected atoms, a simple consideration suggests that their thermal conductivity and specific heat have little effect on it.
Particle deposition onto a microsieve
Authors: Lin Jie , Bourrier David , Dilhan Monique , Duru Paul
Published: July 2009

The objective of the present work is to investigate experimentally the deposition of micron-sized particles onto the surface of a microsieve membrane, which consists in a thin screen with patterned circular holes. A dilute suspension of spherical, monodisperse, polystyrene particles flows at an imposed flow rate through the membrane, in a frontal filtration mode (i.e., the flow direction is perpendicular to the membrane). The particle-to-pore diameter ratio is inferior to one. The particle and flow Reynolds numbers are both smaller than 0.1 for the flow regimes investigated in the present study. The particles are non-Brownian, inertialess, and their buoyancy is negligible. Direct visualizations of the membrane are made using video microscopy. A statistical analysis of the particle deposition locations, based on an automatic processing of video images of the membrane surface recorded during the experiment, is made possible by the periodicity of the pore distribution. Experiments show the existence of two preferential locations for particle deposition, for the whole range of flow rates investigated in the present study and the three microsieve patterns used. This puzzling result is discussed in the light of earlier theoretical and numerical simulations works, dealing with the low Reynolds number motion of a single particle in the vicinity of a pore, in the presence of physicochemical interactions between the particle and the membrane surface.
An experimental guided-ion-beam and ab initio study of the ion-molecule gas-phase reactions between Li+ ions and iso-C3H7Cl in their ground electronic state
Authors: Lucas J. M. , de Andrés J. , Sogas J. , Albertí M. , Bofill J. M. , Bassi D. , Ascenzi D. , Tosi P. , Aguilar A.
Published: July 2009

Reactive collisions between Li+ ions and i-C3H7Cl molecules have been studied in the 0.20–12.00 eV center-of-mass energy range using an octopole radio frequency guided-ion beam apparatus recently developed in our laboratory. At low collision energies, dehydrohalogenation reactions giving rise to Li(C3H6)+ and Li(HCl)+ are the main reaction channels, while at higher ones C3H7+ and C2H3+ become dominant, all their reactive cross sections having been measured as a function of the collision energy. To obtain information about the potential energy surfaces (PESs) on which the reactive processes take place, ab initio calculations at the MP2 level have been performed. For dehydrohalogenations, the reactive ground singlet PES shows ion-molecule adduct formation in both the reactant and product sides of the surface. Following the minimum energy path connecting both minima, an unstable intermediate and the corresponding barriers, both lying below the reactant’s energy, have been characterized. The entrance channel ion-molecule adduct is also involved in the formation of C3H7+, which then generates C2H3+ via an CH4 unimolecular elimination. A qualitative interpretation of the experimental results based on ab initio calculations is also included.
Effect of glass-forming biopreservatives on head group rotational dynamics in freeze-dried phospholipid bilayers: A P31 NMR study
Authors: Jain P. , Sen S. , Risbud S. H.
Published: July 2009

P 31 NMR spectroscopy has been used to elucidate the role of glass-forming sugars in the preservation of dipalmitoylphosphatidylcholine (DPPC) lipid bilayers. P31 wideline NMR spectra of freeze-dried pure DPPC, DPPC/trehalose, DPPC/glucose, and DPPC/hydroxyethyl starch (HES) mixtures collected in the temperature range of 25–80 °C have been simulated to obtain quantitative information about rotational dynamics and orientation of the lipid head groups in these media. In the case of pure DPPC, DPPC/glucose, and DPPC/HES, the gel-to-liquid crystalline phase transition of DPPC bilayer is characterized by a sudden increase in the rate of rotational diffusion of the PO4 head groups near 40 °C. The corresponding rotational jump frequency increases from a few kilohertz in the gel phase to at least several megahertz in the liquid crystalline phase. On the other hand, in the case of DPPC/trehalose mixture the temperature of this onset of rapid head group dynamics is increased by ∼10 °C. Trehalose reduces the lipid head group motions most effectively in the temperature range of T≤50 °C relevant for biopreservation. Additionally, and possibly more importantly, trehalose is found to strongly restrict any change in the orientation of the diffusion axis of the PO4 head groups during the phase transformation. This unique ability of trehalose to maintain the dynamical and orientational rigidity of lipid head groups is likely to be responsible for its superior ability in biopreservation.
Stick-slip dynamics of an oscillated sessile drop
Authors: Fayzrakhmanova Irina S. , Straube Arthur V.
Published: July 2009

We consider theoretically the dynamics of an oscillated sessile drop of incompressible liquid and focus on the contact line hysteresis. We address the situation of the small-amplitude and high-frequency oscillations imposed normally to the substrate surface. We deal with the drop whose equilibrium surface is hemispherical and the equilibrium contact angle equals π/2. We apply the dynamic boundary condition that involves an ambiguous dependence of the contact angle on the contact line velocity: The contact line starts to slide only when the deviation of the contact angle exceeds a certain critical value. As a result, the stick-slip dynamics can be observed. The frequency response of surface oscillations on the substrate and at the pole of the drop are analyzed. It is shown that novel features such as the emergence of antiresonant frequency bands and nontrivial competition of different resonances are caused by contact line hysteresis.
Advantages of blue InGaN multiple-quantum well light-emitting diodes with InGaN barriers
Authors: Kuo Yen-Kuang , Chang Jih-Yuan , Tsai Miao-Chan , Yen Sheng-Horng
Published: July 2009

The advantages of blue InGaN light-emitting diodes (LEDs) with InGaN barriers are studied. The L-I curves, carrier concentrations in the quantum wells, energy band diagrams, and internal quantum efficiency are investigated. The simulation results show that the InGaN/InGaN LED has better performance over its conventional InGaN/GaN counterpart due to the enhancement of electron confinement, the reduced polarization effect between the barrier and well, and the lower potential barrier height for the holes to transport in the active region. The simulation results also suggest that the efficiency droop is markedly improved when the traditional GaN barriers are replaced by InGaN barriers.
Ultraviolet electroluminescence from ZnO/NiO-based heterojunction light-emitting diodes
Authors: Long Hao , Fang Guojia , Huang Huihui , Mo Xiaoming , Xia Wei , Dong Binzhong , Meng Xianquan , Zhao Xingzhong
Published: July 2009

Ultraviolet light-emitting diodes based on ZnO/NiO heterojunctions were fabricated on commercially available n+-GaN/sapphire substrates using a radio frequency magnetron sputtering system. Near band edge emission of ZnO peaking at ∼370 nm with a full-width at half maximum of ∼7 nm was achieved at room temperature when the devices were under sufficient forward bias. With the help of an electron blocking i-Mg1−xZnxO(0<x<1) layer inserted between the ZnO and NiO layers, the emission intensity has been much enhanced and the threshold current drops down to ∼23 from ∼70 mA. The results were discussed in terms of the band diagrams of the heterojunctions.
Vertically emitting terahertz quantum cascade ring lasers
Authors: Mujagić Elvis , Deutsch Christoph , Detz Hermann , Klang Pavel , Nobile Michele , Andrews Aaron Maxwell , Schrenk Werner , Unterrainer Karl , Strasser Gottfried
Published: July 2009

We describe the fabrication and operation of vertically emitting distributed feedback quantum cascade ring lasers operating in the terahertz frequency range. A twofold increase in radiation efficiency is observed as compared to Fabry–Pérot lasers. The emitters exhibit a robust single-mode operation around 3.2 THz with a side mode suppression ratio higher than 30 dB. Modal and threshold characteristics are investigated by performing finite element simulations with results in good agreement with experiments. The ring-shaped resonator facilitates beam collimation which results in a symmetric far-field profile.
Notch pathway regulation of chondrocyte differentiation and proliferation during appendicular and axial skeleton development
Authors: Mead Timothy J. , Yutzey Katherine E.
Published: July 2009

The role of Notch signaling in cartilage differentiation and maturation in vivo was examined. Conditional Notch pathway gain and loss of function was achieved using a Cre/loxP approach to manipulate Notch signaling in cartilage precursors and chondrocytes of the developing mouse embryo. Conditional overexpression of activated Notch intracellular domain (NICD) in the chondrocyte lineage results in skeletal malformations with decreased cartilage precursor proliferation and inhibited hypertrophic chondrocyte differentiation. Likewise, expression of NICD in cartilage precursors inhibits sclerotome differentiation, resulting in severe axial skeleton abnormalities. Furthermore, conditional loss of Notch signaling via
RBP-J
gene deletion in the chondrocyte lineage results in increased chondrocyte proliferation and skeletal malformations consistent with the observed increase in hypertrophic chondrocytes. In addition, the Notch pathway inhibits expression of Sox9 and its target genes required for normal chondrogenic cell proliferation and differentiation. Together, our results demonstrate that appropriate Notch pathway signaling is essential for proper chondrocyte progenitor proliferation and for the normal progression of hypertrophic chondrocyte differentiation into bone in the developing appendicular and axial skeletal elements.
The histone gene activator HINFP is a nonredundant cyclin E/CDK2 effector during early embryonic cell cycles
Authors: Xie Ronglin , Medina Ricardo , Zhang Ying , Hussain Sadiq , Colby Jennifer , Ghule Prachi , Sundararajan Sakthi , Keeler Marilyn , Liu Li-Jun , van der Deen Margaretha , Mitra Partha , Lian Jane B. , Rivera-Perez Jaime A. , Jones Stephen N. , Stein Janet L. , van Wijnen Andre J. , Stein Gary S.
Published: July 2009

Competency for DNA replication is functionally coupled to the activation of histone gene expression at the onset of S phase to form chromatin. Human histone nuclear factor P (HiNF-P; gene symbol
HINFP
) bound to its cyclin E/cyclin-dependent kinase 2 (CDK2) responsive coactivator p220
NPAT
is a key regulator of multiple human
histone H4
genes that encode a major subunit of the nucleosome. Induction of the histone H4 transcription factor (HINFP)/p220
NPAT
coactivation complex occurs in parallel with the CDK-dependent release of pRB from E2F at the restriction point. Here, we show that the downstream CDK-dependent cell cycle effector HINFP is genetically required and, in contrast to the CDK2/cyclin E complex, cannot be compensated. We constructed a mouse
Hinfp
-null mutation and found that heterozygous Hinfp mice survive, indicating that 1 allele suffices for embryogenesis. Homozygous loss-of-function causes embryonic lethality: No homozygous
Hinfp
-null mice are obtained at or beyond embryonic day (E) 6.5. In blastocyst cultures,
Hinfp
-null embryos exhibit a delay in hatching, abnormal growth, and loss of
histone H4
gene expression. Our data indicate that the
CDK2
/
cyclin E
/
p220
NPAT
/
HINFP
/
histone
gene signaling pathway at the G1/S phase transition is an essential, nonredundant cell cycle regulatory mechanism that is established early in embryogenesis.
Epidemiology of Methicillin-Resistant Staphylococcus aureus Bacteremia in Gaborone, Botswana
Authors: Wood Sarah M. , Shah Samir S. , Bafana Margaret , Ratner Adam J. , Meaney Peter A. , Malefho Kolaatamo C. S. , Steenhoff Andrew P.
Published: July 2009

This cross-sectional study at a tertiary-care hospital in Botswana from 2000 to 2007 was performed to determine the epidemiologic characteristics of Staphylococcus aureus bacteremia. We identified a high prevalence (11.2% of bacteremia cases) of methicillin-resistant S. aureus (MRSA) bacteremia. MRSA isolates had higher proportions of resistance to commonly used antimicrobials than did methicillin-susceptible isolates, emphasizing the need to revise empiric prescribing practices in Botswana.
Finding the signal in the noise: objective data-selection criteria improve the assessment of western Baltic spring-spawning herring
Authors: Payne Mark R. , Clausen Lotte Worsøe , Mosegaard Henrik
Published: July 2009

Payne, M. R., Clausen, L. W., and Mosegaard, H. 2009. Finding the signal in the noise: objective data-selection criteria improve the assessment of western Baltic spring-spawning herring. – ICES Journal of Marine Science, 66: 1673–1680. In the art of fish-stock assessment, it is common practice to include all available data without properly testing their validity in terms of their signal-to-noise ratio. The western Baltic spring-spawning herring (Clupea harengus) stock has been historically difficult to assess in a reliable manner. The population is spread between the Skagerrak, Kattegat, the Danish islands, and the western Baltic, but the distribution depends on age and season. Although the distribution area is covered by five separate surveys, none covers the entire stock. Using all time-series data may cause high noise levels and could lead to a poor-quality assessment. We examine the temporal and spatial coverage of each survey in terms of current biological understanding of stock distribution and, employing the observed internal consistency between age classes within cohorts as additional criteria, select the most appropriate data subsets. Assessments based on the revised dataset show greatly improved quality in terms of both accuracy and precision. The results highlight the often-ignored principle that a judicious choice of input data, based on rational and justifiable selection criteria, can enhance the ultimate quality of a stock assessment.
A “seascape genetic” snapshot of Sebastes marinus calls for further investigation across the North Atlantic
Authors: Pampoulie Christophe , Gíslason David , Daníelsdóttir Anna Kristin
Published: July 2009

Pampoulie, C., Gíslason, D., and Daníelsdóttir, A. K. 2009. A “seascape genetic” snapshot of Sebastes marinus calls for further investigation across the North Atlantic. – ICES Journal of Marine Science, 66: 2219–2222. A collection of 376 golden redfish (Sebastes marinus) from several fishing grounds in the North Atlantic in late 2001 was genotyped at nine microsatellite loci to provide preliminary information on the possible genetic structure in this species. Landscape genetic analysis revealed the presence of two distinct genetic pools within the North Atlantic, suggesting that S. marinus might be structured within the North Atlantic and should be the subject of more investigation.
Occurrence of Viruses in Wheat in the Great Plains Region, 2008
Authors: Burrows Mary , Franc Gary , Rush Charlie , Blunt Tamla , Ito Dai , Kinzer Kasia , Olson Jen , O'Mara Judy , Price Jacob , Tande Connie , Ziems Amy , Stack James
Published: July 2009

Field surveys in 2008 determined the prevalence and diversity of viruses present in the Great Plains wheat crops. Symptomatic plants (n = 754) in nine states were tested for Wheat streak mosaic virus (WSMV), Wheat mosaic virus (WMoV, formerly known as High Plains virus), Triticum mosaic virus (TriMV), Barley yellow dwarf virus-PAV (BYDV-PAV), and Cereal yellow dwarf virus-RPV (CYDV-RPV), using indirect ELISA. Virus prevalence varied greatly, with average frequency of detection highest for WSMV (47%), followed by WMoV (19%), TriMV (17%), BYDV-PAV (7%), and lowest for CYDV-RPV (2%). Most positive plant samples (37%) had one virus present, with decreasing frequencies for co-infection by two (19%), three (5%), or four viruses (1%). TriMV was detected for the first time in Colorado, Nebraska, Oklahoma, South Dakota, Texas, and Wyoming. WMoV was identified for the first time in Montana and Wyoming. Chlorotic streaks were more frequently associated with WSMV, WMoV, and TriMV (R = 0.166 to 0.342; P < 0.05), and stunting was more frequently associated with WMoV (R = 0.142; P = 0.004) or TriMV (R = 0.107; P = 0.033) than WSMV. Symptom severity did not increase with co-infection as compared to single virus infections, with the exception of plants co-infected with mite transmitted viruses in Texas.

Accepted for publication 1 May 2009. Published 6 July 2009.
HBZ is an immunogenic protein, but not a target antigen for human T-cell leukemia virus type 1-specific cytotoxic T lymphocytes
Authors: Suemori Koichiro , Fujiwara Hiroshi , Ochi Toshiki , Ogawa Taiji , Matsuoka Masao , Matsumoto Tadashi , Mesnard Jean-Michel , Yasukawa Masaki
Published: July 2009

Recently, HBZ has been reported to play an important role in the proliferation of adult T-cell leukaemia (ATL) cells and might be a target of novel therapy for ATL. To develop a novel immunotherapy for ATL, we verified the feasibility of cellular immunotherapy targeting HBZ. We established an HBZ-specific and HLA-A*0201-restricted cytotoxic T lymphocyte (CTL) clone. Detailed study using this CTL clone clearly showed that HBZ is certainly an immunogenic protein recognizable by human CTLs; however, HBZ-specific CTLs could not lyse ATL cells. Failure of HBZ-specific CTLs to recognize human T-cell leukemia virus type 1 (HTLV-1)-infected cells might be due to a low level of HBZ protein expression in ATL cells and resistance of HTLV-1-infected cells to CTL-mediated cytotoxicity. Although HBZ plays an important role in the proliferation of HTLV-1-infected cells, it may also provide a novel mechanism that allows them to evade immune recognition.
Antibody responses to 26 skin human papillomavirus types in the Netherlands, Italy and Australia
Authors: Waterboer Tim , Neale Rachel , Michael Kristina M. , Sehr Peter , de Koning Maurits N. C. , Weißenborn Sönke J. , Sampogna Francesca , Abeni Damiano , Green Adele C. , Bouwes Bavinck Jan Nico , Pawlita Michael ,   the EPI-HPV-UV-CA Group
Published: July 2009

Solar UV radiation is the main risk factor for cutaneous squamous cell carcinoma (SCC), but infections with skin human papillomavirus (HPV) types have also been linked to the development of SCC. Little is known about the natural history of these infections and whether the seroprevalence of skin HPV types is affected by ambient or individual levels of sun exposure. This study investigated this by analysing sera for antibodies to 26 skin HPV types from five phylogenetic genera obtained from 807 healthy individuals from the Netherlands, Italy and Australia, countries with strong differences in sunlight intensity. Overall HPV seroprevalence was similar across the three countries (50–57 % for β-HPV types, 40–48 % for γ-HPV types), and the most frequent β-HPV and γ-HPV types were the same in all countries. The highest seroprevalences for 24 of the 26 skin HPV types were observed in Italy (14 types) and Australia (ten types). Seroprevalence among men was generally higher than among women, and the male sex was significantly associated with both β-HPV [odds ratio (OR) 2.81, 95 % confidence interval (CI) 1.64–4.82] and γ-HPV (OR 2.42, 95 % CI 1.40–4.18) antibodies in Australia. The only measure of sun sensitivity or UV exposure significantly associated with skin HPV seroprevalence was found for weekend sun exposure in Australia and β-HPV antibodies. It was concluded that type spectra and HPV seroprevalence are similar in countries with different sunlight intensity, and that levels of UV exposure do not play a strong role in the development of skin HPV antibodies in this study population.
Effect of citrus hosts on the generation, maintenance and evolutionary fate of genetic variability of citrus exocortis viroid
Authors: Bernad Lucía , Duran-Vila Núria , Elena Santiago F.
Published: July 2009

Citrus exocortis viroid (CEVd) populations are composed of closely related haplotypes whose frequencies in the population result from the equilibrium between mutation, selection and genetic drift. The genetic diversity of CEVd populations infecting different citrus hosts was studied by comparing populations recovered from infected trifoliate orange and sour orange seedling trees after 10 years of evolution, with the ancestral population maintained for the same period in the original host, Etrog citron. Furthermore, populations isolated from these trifoliate orange and sour orange trees were transmitted back to Etrog citron plants and the evolution of their mutant spectra was studied. The results indicate that (i) the amount and composition of the within-plant genetic diversity generated varies between these two hosts and is markedly different from that which is characteristic of the original Etrog citron host and (ii) the genetic diversity found after transmitting back to Etrog citron is indistinguishable from that which is characteristic of the ancestral Etrog citron population, regardless of the citrus plant from which the evolved populations were isolated. The relationship between the CEVd populations from Etrog citron and trifoliate orange, both sensitive hosts, and those from sour orange, which is a tolerant host, is discussed.
Tick-borne encephalitis virus – a review of an emerging zoonosis
Authors: Mansfield K. L. , Johnson N. , Phipps L. P. , Stephenson J. R. , Fooks A. R. , Solomon T.
Published: July 2009

During the last 30 years, there has been a continued increase in human cases of tick-borne encephalitis (TBE) in Europe, a disease caused by tick-borne encephalitis virus (TBEV). TBEV is endemic in an area ranging from northern China and Japan, through far-eastern Russia to Europe, and is maintained in cycles involving Ixodid ticks (Ixodes ricinusandIxodes persulcatus)and wild vertebrate hosts. The virus causes a potentially fatal neurological infection, with thousands of cases reported annually throughout Europe. TBE has a significant mortality rate depending upon the strain of virus or may cause long-term neurological/neuropsychiatric sequelae in people affected. In this review, we comprehensively reviewed TBEV, its epidemiology and pathogenesis, the clinical manifestations of TBE, along with vaccination and prevention. We also discuss the factors which may have influenced an apparent increase in the number of reported human cases each year, despite the availability of effective vaccines.
Second-site mutations in Borna disease virus overexpressing viral accessory protein X
Authors: Poenisch Marion , Wille Sandra , Schneider Urs , Staeheli Peter
Published: July 2009

The X protein of Borna disease virus (BDV) is an essential factor that regulates viral polymerase activity and inhibits apoptosis of persistently infected cells. We observed that a BDV mutant which carries an additional X gene replicated well in cell culture only after acquiring second-site mutations that selectively reduced expression of the endogenous X gene. In rat brains, the virus acquired additional mutations which inactivated the ectopic X gene or altered the sequence of X. These results demonstrate that BDV readily acquires mutations if strong selection pressure is applied. They further indicate that fine-tuning of X expression determines viral fitness.
Restoration of BRAK / CXCL14 gene expression by gefitinib is associated with antitumor efficacy of the drug in head and neck squamous cell carcinoma
Authors: Ozawa Shigeyuki , Kato Yasumasa , Ito Shin , Komori Reika , Shiiki Naoto , Tsukinoki Keiichi , Ozono Satoru , Maehata Yojiro , Taguchi Takahide , Imagawa‐Ishiguro Yukari , Tsukuda Mamoru , Kubota Eiro , Hata Ryu‐Ichiro
Published: July 2009

Clinical efficacy of gefitinib (ZD1839, Iressa), which is an inhibitor specific for epidermal growth factor (EGF) receptor tyrosine kinase, has been shown in non‐small‐cell lung carcinoma patients with EGF receptor mutations, so these mutations are useful marker(s) to find a responder for the drug. Recent studies have shown that the EGF receptor gene mutation is rare in squamous cell carcinoma in the esophageal and head and neck regions. We previously reported that the expression of the chemokine BRAK/CXCL14 in head and neck squamous cell carcinoma (HNSCC) cells was down‐regulated by EGF treatment, and that forced expression of BRAK in tumor cells decreased the tumorigenicity of the cells in xenografts. Thus, we investigated the relationship between restoration of BRAK expression by gefitinib and the efficacy of the drug for tumor suppression. We found that EGF down‐regulated BRAK expression through the MEK–extracellular signal regulated kinase pathway and that this down‐regulated expression was restored by gefitinib in vitro. Oral administration of gefitinib significantly (P < 0.001) reduced tumor growth of xenografts of three HNSCC cell lines (HSC‐2, HSC‐3, and HSC‐4), in female athymic nude mice, accompanied by an increase in BRAK expression specifically in tumor tissue. This tumor‐suppressing effect of the drug was not observed in the case of BRAK non‐expressing cells. Furthermore introduction of BRAK shRNA vector reduced both the expression levels of BRAK in HSC‐3 cells and the antitumor efficacy of gefitinib in vivo. Our data showing an inverse relationship between BRAK expression levels in tumor cells and the tumor growth rate indicate that the gefitinib‐induced increase in BRAK expression is beneficial for tumor suppression in vivo. (Cancer Sci 2009)
Triptolide abrogates oncogene FIP1L1‐PDGFRα addiction and induces apoptosis in hypereosinophilic syndrome
Authors: Jin Yanli , Chen Qi , Lu Zhongzheng , Chen Bo , Pan Jingxuan
Published: July 2009

The pathogenesis of hypereosinophilic syndrome (HES) in some patients is highly dependent on FIP1‐Like‐1 (FIP1L1)–platelet‐derived growth factor receptor alpha (PDGFRα), which can generate sustained activation signaling to maintain a cell malignant phenotype. HES usually shows good response to the tyrosine kinase inhibitor imatinib, but mutations in FIP1L1‐PDGFRα (e.g. T674I) can confer acquired resistance to imatinib. An alternative therapeutic strategy other than with tyrosine kinase inhibitors is needed to overcome acquired drug resistance. We hypothesized that switching off the crucial chimeric oncoprotein FIP1L1‐PDGFRα on which HES cells depend, should have deleterious effects on the cancer cells. We used low concentrations of triptolide, a transcription inhibitor, to shut down the expression of FIP1L1‐PDGFRα. EOL‐1 cells and BaF3 cells expressing wild‐type or T674I FIP1L1‐PDGFRα were treated with triptolide, and signaling pathways, cell cycling, and apoptosis were analyzed by RT‐PCR, immunoblotting, and flow cytometry, respectively. The results revealed that at nanomolar concentrations triptolide decreased the levels of mRNA and protein of FIP1L1‐PDGFRα and the growth of the neoplastic cells, regardless of the mutational status of PDGFRα. Triptolide also downregulated the signaling molecules Stat3, Akt, and Erk1/2, which are downstream from PDGFRα, and induced G1 cell‐cycle arrest. Triptolide time‐ and dose‐dependently induced apoptosis by decreasing the anti‐apoptotic proteins Mcl‐1 and Bcl‐XL,triggering the intrinsic apoptotic pathway. In conclusion, triptolide has potent activity against malignant cells in HES bearing FIP1L1‐PDGFRα, regardless of its mutational status that confer acquired resistance to imatinib. Our results suggest that triptolide may be a promising agent in the treatment of HES. (Cancer Sci 2009; 00: 000–000)