bluuebunny/crossref_metadata_2025 huggingface dataset:
Spindelzellige Weichgewebstumoren des Para- u. Retropharyngealraums: 5 Patienten, Literaturübersicht
Authors: Prera N. , Zorob M. , Heinz J. , Uhlig I. , Maier W.
Published: May 2015

Hintergrund: Der Parapharyngealraum (PPR) ist der klinischen Untersuchung aufgrund seiner komplexen Anatomie schlecht zugänglich. Neoplasien in diesem Bereich sind selten, werden spät symptomatisch und im fortgeschrittenen Stadium diagnostiziert. Es werden multiple Entitäten differenziert, wobei maligne mesenchymale Tumore ungewöhnlich sind.

Patienten: Wir schildern charakteristische Verlaufsformen spindelzelliger Weichgewebstumore im PPR anhand von 5 Patienten: 2 Fälle eines Synovialsarkomes (SyS), 2 Fälle eines malignen peripheren Nervenscheidentumors (MPNST) ohne Neurofibromatose, 1 Fall eines Ektomesenchymomes (EM).

Ergebnisse: Bei beiden Patienten mit SyS zeigte sich unter multimodaler Therapie mittels Operation, Chemotherapie und Radiatio eine schnelle Tumorprogredienz und frühe pulmonale Metastasierung. Die beiden Patientinnen mit MPNST waren nach Tumorresektion und in einem der Fälle adjuvanter Radiatio rezidivfrei. Die Patientin mit EM zeigte nach operativer Resektion bisher kein Rezidiv.

Schlussfolgerung: Da maligne mesenchymale Tumore des PPR ungewöhnlich sind und nicht das typische Metastasierungsverhalten epithelialer Neoplasien oder maligner Lymphome aufweisen, kann sich die Diagnosestellung verzögern. Es ist wichtig bei atypischen Raumforderungen im PPR an die Möglichkeit eines Weichgewebstumors zu denken und die diagnostischen Schritte zu veranlassen. Die Bildgebung der Wahl zur Darstellung des PPR ist die MRT, nach Diagnosestellung ist ein an die Entität adaptiertes Staging notwendig. Die histologische Differenzierung mittels Immunhistochemie und Molekulargenetik ist aufwendig, stellt aber eine entscheidende Voraussetzung zur Festlegung der optimalen Therapie dar. Diagnostik und Therapie sollten daher in einem spezialisierten Zentrum erfolgen.
Optimal Ge/SiGe nanofin geometries for hole mobility enhancement: Technology limit from atomic simulations
Authors: Vedula Ravi Pramod , Mehrotra Saumitra , Kubis Tillmann , Povolotskyi Michael , Klimeck Gerhard , Strachan Alejandro
Published: May 2015

We use first principles simulations to engineer Ge nanofins for maximum hole mobility by controlling strain tri-axially through nano-patterning. Large-scale molecular dynamics predict fully relaxed, atomic structures for experimentally achievable nanofins, and orthogonal tight binding is used to obtain the corresponding electronic structure. Hole transport properties are then obtained via a linearized Boltzmann formalism. This approach explicitly accounts for free surfaces and associated strain relaxation as well as strain gradients which are critical for quantitative predictions in nanoscale structures. We show that the transverse strain relaxation resulting from the reduction in the aspect ratio of the fins leads to a significant enhancement in phonon limited hole mobility (7× over unstrained, bulk Ge, and 3.5× over biaxially strained Ge). Maximum enhancement is achieved by reducing the width to be approximately 1.5 times the height and further reduction in width does not result in additional gains. These results indicate significant room for improvement over current-generation Ge nanofins, provide geometrical guidelines to design optimized geometries and insight into the physics behind the significant mobility enhancement.
Identification of two-step chemical mechanisms using small temperature oscillations and a single tagged species
Authors: Closa F. , Gosse C. , Jullien L. , Lemarchand A.
Published: May 2015

In order to identify two-step chemical mechanisms, we propose a method based on a small temperature modulation and on the analysis of the concentration oscillations of a single tagged species involved in the first step. The thermokinetic parameters of the first reaction step are first determined. Then, we build test functions that are constant only if the chemical system actually possesses some assumed two-step mechanism. Next, if the test functions plotted using experimental data are actually even, the mechanism is attributed and the obtained constant values provide the rate constants and enthalpy of reaction of the second step. The advantage of the protocol is to use the first step as a probe reaction to reveal the dynamics of the second step, which can hence be relieved of any tagging. The protocol is anticipated to apply to many mechanisms of biological relevance. As far as ligand binding is considered, our approach can address receptor conformational changes or dimerization as well as competition with or modulation by a second partner. The method can also be used to screen libraries of untagged compounds, relying on a tracer whose concentration can be spectroscopically monitored
Optimizing the fabrication process and interplay of device components of polymer solar cells using a field-based multiscale solar-cell algorithm
Authors: Donets Sergii , Pershin Anton , Baeurle Stephan A.
Published: May 2015

Both the device composition and fabrication process are well-known to crucially affect the power conversion efficiency of polymer solar cells. Major advances have recently been achieved through the development of novel device materials and inkjet printing technologies, which permit to improve their durability and performance considerably. In this work, we demonstrate the usefulness of a recently developed field-based multiscale solar-cell algorithm to investigate the influence of the material characteristics, like, e.g., electrode surfaces, polymer architectures, and impurities in the active layer, as well as post-production treatments, like, e.g., electric field alignment, on the photovoltaic performance of block-copolymer solar-cell devices. Our study reveals that a short exposition time of the polymer bulk heterojunction to the action of an external electric field can lead to a low photovoltaic performance due to an incomplete alignment process, leading to undulated or disrupted nanophases. With increasing exposition time, the nanophases align in direction to the electric field lines, resulting in an increase of the number of continuous percolation paths and, ultimately, in a reduction of the number of exciton and charge-carrier losses. Moreover, we conclude by modifying the interaction strengths between the electrode surfaces and active layer components that a too low or too high affinity of an electrode surface to one of the components can lead to defective contacts, causing a deterioration of the device performance. Finally, we infer from the study of block-copolymer nanoparticle systems that particle impurities can significantly affect the nanostructure of the polymer matrix and reduce the photovoltaic performance of the active layer. For a critical volume fraction and size of the nanoparticles, we observe a complete phase transformation of the polymer nanomorphology, leading to a drop of the internal quantum efficiency. For other particle-numbers and -sizes, we observe only a local perturbation of the nanostructure, diminishing the number of continuous percolation paths to the electrodes and, therefore, reducing the device performance. From these investigations, we conclude that our multiscale solar-cell algorithm is an effective approach to investigate the impact of device materials and post-production treatments on the photovoltaic performance of polymer solar cells.
Determining the static electronic and vibrational energy correlations via two-dimensional electronic-vibrational spectroscopy
Authors: Dong Hui , Lewis Nicholas H. C. , Oliver Thomas A. A. , Fleming Graham R.
Published: May 2015

Changes in the electronic structure of pigments in protein environments and of polar molecules in solution inevitably induce a re-adaption of molecular nuclear structure. Both changes of electronic and vibrational energies can be probed with visible or infrared lasers, such as two-dimensional electronic spectroscopy or vibrational spectroscopy. The extent to which the two changes are correlated remains elusive. The recent demonstration of two-dimensional electronic-vibrational (2DEV) spectroscopy potentially enables a direct measurement of this correlation experimentally. However, it has hitherto been unclear how to characterize the correlation from the spectra. In this paper, we present a theoretical formalism to demonstrate the slope of the nodal line between the excited state absorption and ground state bleach peaks in the spectra as a characterization of the correlation between electronic and vibrational transition energies. We also show the dynamics of the nodal line slope is correlated to the vibrational spectral dynamics. Additionally, we demonstrate the fundamental 2DEV spectral line-shape of a monomer with newly developed response functions.
Application of two-dimensional infrared spectroscopy to benchmark models for the amide I band of proteins
Authors: Bondarenko Anna S. , Jansen Thomas L. C.
Published: May 2015

In this paper, we present a novel benchmarking method for validating the modelling of vibrational spectra for the amide I region of proteins. We use the linear absorption spectra and two-dimensional infrared spectra of four experimentally well-studied proteins as a reference and test nine combinations of molecular dynamics force fields, vibrational frequency mappings, and coupling models. We find that two-dimensional infrared spectra provide a much stronger test of the models than linear absorption does. The best modelling approach in the present study still leaves significant room for future improvement. The presented benchmarking scheme, thus, provides a way of validating future protocols for modelling the amide I band in proteins.
Mechanical characterization between room temperature and 1000 °C of SiC free-standing thin films by a novel high-temperature micro-tensile setup
Authors: Leisen D. , Rusanov R. , Rohlfing F. , Fuchs T. , Eberl C. , Riesch-Oppermann H. , Kraft O.
Published: May 2015

A novel high-temperature micro-tensile setup allows the characterization of the elastic and plastic as well as creep behavior of free-standing thin films at temperatures of up to 1000 °C. Correspondingly, a new layout for free-standing thin film tensile test structures has been developed, enabling accurate self-alignment upon loading. Furthermore, a differential optical strain measurement technique as well as optimizations of the optical path has been implemented, providing a strain resolution of well below 1 × 10−4 at 1000 °C. Two different polycrystalline SiC free-standing thin films have been investigated in tension to acquire stress-strain data and corresponding Young’s modulus at up to 1000 °C. The high sensitivity of the strain measurement technique makes it also possible to identify creep strains in the high-temperature regime.
Ensemble density functional theory method correctly describes bond dissociation, excited state electron transfer, and double excitations
Authors: Filatov Michael , Huix-Rotllant Miquel , Burghardt Irene
Published: May 2015

State-averaged (SA) variants of the spin-restricted ensemble-referenced Kohn-Sham (REKS) method, SA-REKS and state-interaction (SI)-SA-REKS, implement ensemble density functional theory for variationally obtaining excitation energies of molecular systems. In this work, the currently existing version of the SA-REKS method, which included only one excited state into the ensemble averaging, is extended by adding more excited states to the averaged energy functional. A general strategy for extension of the REKS-type methods to larger ensembles of ground and excited states is outlined and implemented in extended versions of the SA-REKS and SI-SA-REKS methods. The newly developed methods are tested in the calculation of several excited states of ground-state multi-reference systems, such as dissociating hydrogen molecule, and excited states of donor–acceptor molecular systems. For hydrogen molecule, the new method correctly reproduces the distance dependence of the lowest excited state energies and describes an avoided crossing between the doubly excited and singly excited states. For bithiophene–perylenediimide stacked complex, the SI-SA-REKS method correctly describes crossing between the locally excited state and the charge transfer excited state and yields vertical excitation energies in good agreement with the ab initio wavefunction methods.
Improved understanding of the spark plasma sintering process
Authors: Hitchcock Dale , Livingston Roger , Liebenberg Donald
Published: May 2015

The process by which spark plasma sintering produces high densification of powder specimens is examined to determine the role of sparks and plasma. Measurements are reported of the electromagnetic emission during the pulsing current using the state-of-the-art Tektronix MDO4104B-6 to obtain voltage vs time and simultaneously radio frequency (rf) emission in selected power vs frequency regions. The results show strong rf emission over the selected frequency region 0–160 kHz during pulsing and nearly an order of magnitude decrease of power during pulsing but in the gap (no pulse). These measurements showed no rf emission dependence on the electrical conductivity of the specimen or with current levels between 0–500 A and support the conclusion that no sparking or plasma production takes place in the specimen. The steep slope of the current vs time profile is demonstrated to produce the rf emission in a manner described by Hertz and is suggested to provide forces on the sintering material that encourage densification.
Magneto-electric interactions at bending resonance in an asymmetric multiferroic composite: Theory and experiment on the influence of electrode position
Authors: Sreenivasulu G. , Qu P. , Petrov V. M. , Qu Hongwei , Srinivasan G.
Published: May 2015

In magnetostrictive-piezoelectric bilayers the strength of mechanical strain mediated magneto-electric (ME) interactions shows a resonance enhancement at bending modes. Such composites when operating under frequency modulation at bending resonance have very high ME sensitivity and are of importance for ultrasensitive magnetometers. This report provides an avenue for further enhancement in the ME sensitivity by strategic positioning of the electrodes in the bilayer. We discuss the theory and measurements on the dependence of ME coupling on the position of electrodes in a lead zirconate titanate-permendur bilayer. Samples of effective length L with full electrodes and partial electrodes of length l = L/3 are studied. A five-fold increase in ME voltage coefficient (MEVC) at bending resonance and a 75% increase in low-frequency MEVC are measured as the partial electrode position is moved from the free-end to clamped-end of the bilayer. When the partial electrode is close to the clamped end, the low-frequency and resonance MEVC are 22% and 45% higher, respectively, than for fully electroded bilayer. According to the model discussed here these observations could be attributed to non-uniform stress along the sample length under flexural deformation. Such deformations are stronger at the free-end than at the clamped-end, thereby reducing the stress produced by applied magnetic fields and a reduction in MEVC. Estimates of MEVC are in good agreement with the data.
The abnormal electrical and optical properties in Na and Ni codoped BiFeO3 nanoparticles
Authors: Xu Xunling , Liu Weifang , Zhang Hong , Guo Minchen , Wu Ping , Wang Shouyu , Gao Ju , Rao Guanghui
Published: May 2015

Bi0.97Na0.03Fe1−xNixO3 (x = 0, 0.005, 0.01, 0.015) nanoparticles are prepared via a sol-gel method. Weak ferromagnetism and exchange bias phenomenon without field cooling are observed in the samples. The oxygen vacancy concentration and leakage current density are increased with increasing the Ni content. However, with the increase of Ni content, the band gap of Bi0.97Na0.03Fe1−xNixO3 nanoparticles first decreases and then increases. To explain the abnormal phenomenon, the interplay of oxygen vacancy donor and hole acceptor is analyzed and a phenomenological qualitative model based on the electronic energy band is proposed. Additionally, the threshold switching behavior appears in Bi0.97Na0.03Fe1−xNixO3 samples with x = 0.01, 0.015 and the effect is qualitatively explained by introducing a conducting channel model based on the high-density mobile charges.
Synthesis, characterization, and magnetically guided antiproliferative activity studies of drug-loaded superparamagnetic nanovectors
Authors: Luna Carlos , Vázquez Ortega Salvador , Barriga-Castro Enrique Díaz , Mendoza-Reséndez Raquel , Gómez-Treviño Alberto
Published: May 2015

Commonly, the key players in anticancer therapies and, more specifically, antineoplastic drugs display poor water solubility and slow dissolution rates. As a consequence, they present low bioavailability, poor tissue distribution, and unfavorable pharmacokinetic profiles, limiting their use. To overcome these barriers and improve efficacy, various drug formulations and delivery strategies have been developed. For example, nanoparticles can be used as drug delivery vehicles and current research is encouraging. However, the intra-tumoral diffusion of functionalized nanovehicles remains to be achieved. In the present study, the anticancer drug paclitaxel was loaded into superparamagnetic nanoparticles and characterized. Novel in vitro experiments based on one or two layers of cells revealed important information about the conditions required to achieve efficient drug intra-tumoral diffusion, using these superparamagnetic nanovectors, once they have been localized by external magnetic fields. These studies indicated that ultralow concentrations of paclitaxel (i.e., tenths of ng/μl) significantly reduce the viability of neoplastic cells when they are delivered with control using these nanovectors. Moreover, we showed that a discontinuous application of a magnetic field promotes the localization of the nanoparticles in a targeted region and favors the subsequent dissemination of the nanoparticles between cellular layers.
Elementary framework for cold field emission from quantum-confined, non-planar emitters
Authors: Patterson A. A. , Akinwande A. I.
Published: May 2015

For suitably small field emitters, the effects of quantum confinement at the emitter tip may have a significant impact on the emitter performance and total emitted current density (ECD). Since the geometry of a quantum system uniquely determines the magnitude and distribution of its energy levels, a framework for deriving ECD equations from cold field electron emitters of arbitrary geometry and dimensionality is developed. In the interest of obtaining semi-analytical ECD equations, the framework is recast in terms of plane wave solutions to the Schrödinger equation via the use of the Jeffreys-Wentzel-Kramers-Brillouin approximation. To demonstrate the framework's consistency with our previous work and its capabilities in treating emitters with non-planar geometries, ECD equations were derived for the normally unconfined cylindrical nanowire (CNW) and normally confined (NC) CNW emitter geometries. As a function of the emitter radius, the NC CNW emitter ECD profile displayed a strong dependence on the Fermi energy and had an average ECD that exceeded the Fowler-Nordheim equation for typical values of the Fermi energy due to closely spaced, singly degenerate energy levels (excluding electron spin), comparatively large electron supply values, and the lack of a transverse, zero-point energy. Such characteristics suggest that emitters with non-planar geometries may be ideal for emission from both an electron supply and electrostatics perspective.
Observation of interface dependent spin polarized photocurrents in InAs/GaSb superlattice
Authors: Li Yuan , Liu Yu , Zhu Laipan , Qin Xudong , Wu Qing , Huang Wei , Niu Zhichuan , Xiang Wei , Hao Hongyue , Chen Yonghai
Published: May 2015

In this letter, we investigated the spin polarized photocurrents excited by mid-infrared radiation and near-infrared radiation, respectively, in InAs/GaSb type II superlattices with different kinds of interfaces. By periodically varying the polarization state of the radiation, we analyzed Rashba-type and Dresselhaus-type spin polarized photocurrents, which present different features depending on the interface types and excitation conditions. Under mid-infrared excitation, the ratio of Rashba-type and Dresselhaus-type spin polarized photocurrents of the superlattice with InSb-like interface is obviously larger than that of the superlattice with GaAs-like interface, the ratio of the superlattice with alternate interface is in the middle. Whereas under near-infrared excitation, the ratios of the three superlattices are nearly the same. Further researches reveal the synactic effects of interface dependent strain and asymmetric interface potential on the spin splitting. Besides, the polarized Raman spectroscopies of these structures were also analyzed.
Breakdown of atmospheric pressure microgaps at high excitation frequencies
Authors: Levko Dmitry , Raja Laxminarayan L.
Published: May 2015

Microwave (mw) breakdown of atmospheric pressure microgaps is studied by a one-dimensional Particle-in-Cell Monte Carlo Collisions numerical model. The effect of both field electron emission and secondary electron emission (due to electron impact, ion impact, and primary electron reflection) from surfaces on the breakdown process is considered. For conditions where field emission is the dominant electron emission mechanism from the electrode surfaces, it is found that the breakdown voltage of mw microdischarge coincides with the breakdown voltage of direct-current (dc) microdischarge. When microdischarge properties are controlled by both field and secondary electron emission, breakdown voltage of mw microdischarge exceeds that of dc microdischarge. When microdischarge is controlled only by secondary electron emission, breakdown voltage of mw microdischarge is smaller than that of dc microdischarge. It is shown that if the interelectrode gap exceeds some critical value, mw microdischarge can be ignited only by electrons initially seeded within the gap volume. In addition, the influence of electron reflection and secondary emission due to electron impact is studied.
Communication: Intraparticle segregation of structurally homogeneous polyelectrolyte microgels caused by long-range Coulomb repulsion
Authors: Rumyantsev Artem M. , Rudov Andrey A. , Potemkin Igor I.
Published: May 2015

Structurally homogeneous polyelectrolyte microgels in dilute aqueous solutions are shown to exhibit inhomogeneous density profile including intraparticle “phase” coexistence of hollow core and dense “skin.” This effect is a consequence of long-range Coulomb repulsion of charged groups which appear because of entropy-driven escape of monovalent counterions into the outer solvent. Excess of the charged groups at the periphery of the microgel particle reduces electrostatic energy and overall free energy of the system despite a penalty in the elastic free energy of strongly stretched subchains in the hole. This finding can serve as additional tool controlling encapsulation, transport, and release of high- and low-molecular-weight species in processes where the microgels are used as delivery systems.
Linear regime of two-plasmon decay and stimulated Raman scattering instability near the quarter-critical density in plasmas
Authors: Wen H. , Yan R. , Maximov A. V. , Ren C.
Published: May 2015

A model for the interaction between the laser light and the plasma waves near the quarter-critical density in plasmas has been studied. This model includes, but is not limited to, the instabilities of two-plasmon decay (TPD) and stimulated Raman scattering (SRS). The full simulation results show the instability growth in the wavevector domains corresponding to TPD and SRS, respectively, and the domain between those two. The instability growth rates and thresholds can be calculated in our model for the parameters of the inertial confinement fusion experiments without the approximations common in analytical theories.
An exact formulation of the time-ordered exponential using path-sums
Authors: Giscard P.-L. , Lui K. , Thwaite S. J. , Jaksch D.
Published: May 2015

We present the path-sum formulation for the time-ordered exponential of a time-dependent matrix. The path-sum formulation gives the time-ordered exponential as a branched continued fraction of finite depth and breadth. The terms of the path-sum have an elementary interpretation as self-avoiding walks and self-avoiding polygons on a graph. Our result is based on a representation of the time-ordered exponential as the inverse of an operator, the mapping of this inverse to sums of walks on a graphs, and the algebraic structure of sets of walks. We give examples demonstrating our approach. We establish a super-exponential decay bound for the magnitude of the entries of the time-ordered exponential of sparse matrices. We give explicit results for matrices with commonly encountered sparse structures.
Prediction of new high pressure structural sequence in thorium carbide: A first principles study
Authors: Sahoo B. D. , Joshi K. D. , Gupta Satish C.
Published: May 2015

In the present work, we report the detailed electronic band structure calculations on thorium monocarbide. The comparison of enthalpies, derived for various phases using evolutionary structure search method in conjunction with first principles total energy calculations at several hydrostatic compressions, yielded a high pressure structural sequence of NaCl type (B1) → Pnma → Cmcm → CsCl type (B2) at hydrostatic pressures of ∼19 GPa, 36 GPa, and 200 GPa, respectively. However, the two high pressure experimental studies by Gerward et al. [J. Appl. Crystallogr. 19, 308 (1986); J. Less-Common Met. 161, L11 (1990)] one up to 36 GPa and other up to 50 GPa, on substoichiometric thorium carbide samples with carbon deficiency of ∼20%, do not report any structural transition. The discrepancy between theory and experiment could be due to the non-stoichiometry of thorium carbide samples used in the experiment. Further, in order to substantiate the results of our static lattice calculations, we have determined the phonon dispersion relations for these structures from lattice dynamic calculations. The theoretically calculated phonon spectrum reveal that the B1 phase fails dynamically at ∼33.8 GPa whereas the Pnma phase appears as dynamically stable structure around the B1 to Pnma transition pressure. Similarly, the Cmcm structure also displays dynamic stability in the regime of its structural stability. The B2 phase becomes dynamically stable much below the Cmcm to B2 transition pressure. Additionally, we have derived various thermophysical properties such as zero pressure equilibrium volume, bulk modulus, its pressure derivative, Debye temperature, thermal expansion coefficient and Gruneisen parameter at 300 K and compared these with available experimental data. Further, the behavior of zero pressure bulk modulus, heat capacity and Helmholtz free energy has been examined as a function temperature and compared with the experimental data of Danan [J. Nucl. Mater. 57, 280 (1975)].
YBa2Cu3O7 microwave resonators for strong collective coupling with spin ensembles
Authors: Ghirri A. , Bonizzoni C. , Gerace D. , Sanna S. , Cassinese A. , Affronte M.
Published: May 2015

Coplanar microwave resonators made of 330 nm-thick superconducting YBa2Cu3O7 have been realized and characterized in a wide temperature (T, 2–100 K) and magnetic field (B, 0–7 T) range. The quality factor (QL) exceeds 104 below 55 K and it slightly decreases for increasing fields, remaining 90% of QL(B=0) for B = 7 T and T = 2 K. These features allow the coherent coupling of resonant photons with a spin ensemble at finite temperature and magnetic field. To demonstrate this, collective strong coupling was achieved by using di(phenyl)-(2,4,6-trinitrophenyl)iminoazanium organic radical placed at the magnetic antinode of the fundamental mode: the in-plane magnetic field is used to tune the spin frequency gap splitting across the single-mode cavity resonance at 7.75 GHz, where clear anticrossings are observed with a splitting as large as ∼82 MHz at T = 2 K. The spin-cavity collective coupling rate is shown to scale as the square root of the number of active spins in the ensemble.
Actuation and transduction of resonant vibrations in GaAs/AlGaAs-based nanoelectromechanical systems containing two-dimensional electron gas
Authors: Shevyrin A. A. , Pogosov A. G. , Budantsev M. V. , Bakarov A. K. , Toropov A. I. , Rodyakina E. E. , Shklyaev A. A.
Published: May 2015

Driven vibrations of a nanoelectromechanical system based on GaAs/AlGaAs heterostructure containing two-dimensional electron gas are experimentally investigated. The system represents a conductive cantilever with the free end surrounded by a side gate. We show that out-of-plane flexural vibrations of the cantilever are driven when alternating signal biased by a dc voltage is applied to the in-plane side gate. We demonstrate that these vibrations can be on-chip linearly transduced into a low-frequency electrical signal using the heterodyne down-mixing method. The obtained data indicate that the dominant physical mechanism of the vibrations actuation is capacitive interaction between the cantilever and the gate.
Anisotropic optical properties of semipolar AlGaN layers grown on m-plane sapphire
Authors: Feneberg Martin , Winkler Michael , Klamser Juliane , Stellmach Joachim , Frentrup Martin , Ploch Simon , Mehnke Frank , Wernicke Tim , Kneissl Michael , Goldhahn Rüdiger
Published: May 2015

The valence band order of AlxGa  1−x N is investigated experimentally by analyzing the anisotropic dielectric functions of semipolar (112¯2) AlGaN thin films grown on m-plane Al2O3. Point-by-point fitted dielectric functions are obtained by spectroscopic ellipsometry and corresponding inter-band transition energies are extracted. The known strain situation of the sample layers is used to correct for the small strain-induced energy shifts within k · p perturbation theory. It also is used to identify transitions related to the three valence bands. Transitions with E ⊥ c from the Γ9 valence band verify an inter-band bowing parameter of b=0.9 eV. The transitions with E || c allow determining the crystal field splitting energy which can be described by a linear interpolation between the values for GaN and AlN satisfactorily.
All-optical depletion of dark excitons from a semiconductor quantum dot
Authors: Schmidgall E. R. , Schwartz I. , Cogan D. , Gantz L. , Heindel T. , Reitzenstein S. , Gershoni D.
Published: May 2015

Semiconductor quantum dots are considered to be the leading venue for fabricating on-demand sources of single photons. However, the generation of long-lived dark excitons imposes significant limits on the efficiency of these sources. We demonstrate a technique that optically pumps the dark exciton population and converts it to a bright exciton population, using intermediate excited biexciton states. We show experimentally that our method considerably reduces the dark exciton population while doubling the triggered bright exciton emission, approaching thereby near-unit fidelity of quantum dot depletion.
Ultra-thin distributed Bragg reflectors via stacked single-crystal silicon nanomembranes
Authors: Cho Minkyu , Seo Jung-Hun , Lee Jaeseong , Zhao Deyin , Mi Hongyi , Yin Xin , Kim Munho , Wang Xudong , Zhou Weidong , Ma Zhenqiang
Published: May 2015

In this paper, we report ultra-thin distributed Bragg reflectors (DBRs) via stacked single-crystal silicon (Si) nanomembranes (NMs). Mesh hole-free single-crystal Si NMs were released from a Si-on-insulator substrate and transferred to quartz and Si substrates. Thermal oxidation was applied to the transferred Si NM to form high-quality SiO2 and thus a Si/SiO2 pair with uniform and precisely controlled thicknesses. The Si/SiO2 layers, as smooth as epitaxial grown layers, minimize scattering loss at the interface and in between the layers. As a result, a reflection of 99.8% at the wavelength range from 1350 nm to 1650 nm can be measured from a 2.5-pair DBR on a quartz substrate and 3-pair DBR on a Si substrate with thickness of 0.87 μm and 1.14 μm, respectively. The high reflection, ultra-thin DBRs developed here, which can be applied to almost any devices and materials, holds potential for application in high performance optoelectronic devices and photonics applications.
Response of soil nitrous oxide flux to nitrogen fertiliser application and legume rotation in a semi-arid climate, identified by smoothing spline models
Authors: Officer Sally Jane , Phillips Frances , Kearney Gavin , Armstrong Roger , Graham John , Partington Debra
Published: May 2015

Although large areas of semi-arid land are extensively cropped, few studies have investigated the effect of nitrogen (N) fertiliser on nitrous oxide (N2O) emissions in these regions (Galbally et al. 2010). These emissions need to be measured in order to estimate N losses and calculate national greenhouse gas inventories. We examined the effect of different agronomic management practices applied to wheat (Triticum aestivum) grown on an alkaline Vertosol in south-eastern Australia on N2O emissions. In 2007, N2O emissions were measured over 12 months, during which N fertiliser (urea) was applied at sowing or N fertiliser plus supplementary irrigation (50 mm) was applied during the vegetative stage and compared with a treatment of no N fertiliser or irrigation. In a second experiment (2008), the effect of source of N on N2O emissions was examined. Wheat was grown on plots where either a pulse (field peas, Pisum sativum) or pasture legume (barrel medic, Medicago truncatula) crop had been sown in the previous season compared with a non-legume crop (canola, Brassica napus). To account for the N supplied by the legume phase, N fertiliser (50 kg N ha–1 as urea) was applied only to the wheat in the plots previously sown to canola. Fluxes of N2O were measured on a sub-daily basis (up to 16 measurements per chamber) by using automated chamber enclosures and a tuneable diode laser, and treatment differences were evaluated by a linear mixed model including cubic smoothing splines. Fluxes were low and highly variable, ranging from –3 to 28 ng N2O-N m–2 s–1. The application of N fertiliser at sowing increased N2O emissions for ~2 months after the fertiliser was applied. Applying irrigation (50 mm) during the vegetative growth stage produced a temporary (~1-week) but non-significant increase in N2O emissions compared with plots that received N fertiliser at sowing but were not irrigated. Including a legume in the rotation significantly increased soil inorganic N at sowing of the following wheat crop by 38 kg N ha–1 (field peas) or 57 kg ha–1 (barrel medic) compared with a canola crop. However, N2O emissions were greater in wheat plots where N fertiliser was applied than where wheat was sown into legume plots where no N fertiliser was applied. Over the 2 years of the field study, N2O emissions attributed to fertiliser ranged from 41 to 111 g N2O-N ha–1, and averaged of 75 g N2O-N ha–1 or 0.15% of the applied N fertiliser. Our findings confirm that the proportion of N fertiliser emitted as N2O from rainfed grain crops grown in Australian semi-arid regions is less than the international average of 1.0%.
Effect of straw returning in winter fallow in Chinese rice fields on greenhouse gas emissions: evidence from an incubation study
Authors: Wu Yupeng , Liu Tian , Peng Qi'an , Shaaban Muhammad , Hu Ronggui
Published: May 2015

Many studies have been performed to compare different straw-returning methods that could provide environmental benefits. However, few studies have focused on the greenhouse gas emissions from straw returning under winter water-stored fields (flooded conditions) and winter fallow fields (non-flooded conditions), which are the common land use types after the rice harvest in southern China. Thus, in the present microcosm incubation experiment, CO2, CH4 and N2O emissions were compared under flooded and non-flooded soil conditions, following straw incorporation. Straw application stimulated CO2 cumulative emission, and this effect was exacerbated by flooding (1818 and 4271 mg kg–1 under non-flooded and flooded conditions, respectively). Although the application of straw can mitigate N2O cumulative emissions under flooded conditions (10 152 μg kg–1 without and –51 μg kg–1 with straw incorporation, respectively), higher CO2 and CH4 production was detected (4271 and 149.20 mg kg–1 for CO2 and CH4 cumulative emissions, respectively). In contrast, straw application under non-flooded conditions had a relatively low global warming potential value (1836 mg CO2 Eq kg–1). Consequently, winter fallow field is recommended after the integrated application of straw and nitrogen fertiliser because of its low global warming potential. However, different strategies may be required for long-term reduction in global warming potential values.
Transcriptome diversity among rice root types during asymbiosis and interaction with arbuscular mycorrhizal fungi
Authors: Gutjahr Caroline , Sawers Ruairidh J. H. , Marti Guillaume , Andrés-Hernández Liliana , Yang Shu-Yi , Casieri Leonardo , Angliker Herbert , Oakeley Edward J. , Wolfender Jean-Luc , Abreu-Goodger Cei , Paszkowski Uta
Published: May 2015

Significance

Plant roots function as an interface between plants and the complex soil environment. Root systems of higher plants consist of different root types (RTs) that maximize their adaptive potential in heterogenous soil for nutrient uptake and anchorage. This study pioneers the molecular examination of individual RTs of adult rice root systems. The global signature of the transcriptional activity of each RT reveals significant quantitative and qualitative differences that predict functional diversity and specialization. Interaction with naturally prevalent beneficial mycorrhizal fungi profoundly modulated the relationship across the RTs such that the crown root transcriptome resembled that of lateral roots. The alteration of secondary cell wall synthesis in colonized roots is consistent with previously reported changes in root system architecture of mycorrhizal plants.
Activity of Antibiotics against Mycobacterium Species Commonly Found in Laboratory Zebrafish
Authors: Chang Carolyn T. , Whipps Christopher M.
Published: May 2015

The Zebrafish Danio rerio is a popular vertebrate model organism used in a wide range of research fields. Importance is placed on Zebrafish health and the maintenance of disease-free laboratory fish so that experimental studies are not inadvertently affected. Mycobacteriosis, a common infection of laboratory Zebrafish, is caused by several Mycobacterium species. Little is known regarding the potential of antibiotic treatment for Zebrafish mycobacteriosis; however, treatment of infected Zebrafish may be appropriate to maintain valuable strains. Here, we investigated, in vitro, the antibiotic susceptibility of both rapid- and slow-growing isolates of Mycobacterium species from laboratory Zebrafish. Antibiotic testing was carried out using a commercially available 96-well microtiter plate format. Results indicated that some but not all antibiotics tested were effective at inhibiting mycobacterial growth and that susceptibility varied among species and strains. Tigecycline, tobramycin, clarithromycin, and amikacin were most effective at broad inhibition of rapid-growing mycobacteria; whereas, amikacin, clarithromycin, and rifampin were effective at inhibiting all slow-growing M. marinum strains tested. Results support the potential for targeted antibiotic treatment of Zebrafish infected with mycobacteria, but additional testing should be carried out in vivo.

Received October 1, 2014; accepted January 4, 2015
MgcRacGAP restricts active RhoA at the cytokinetic furrow and both RhoA and Rac1 at cell–cell junctions in epithelial cells
Authors: Breznau Elaina B. , Semack Ansley C. , Higashi Tomohito , Miller Ann L.
Published: May 2015

Localized activation of Rho GTPases is essential for multiple cellular functions, including cytokinesis and formation and maintenance of cell–cell junctions. Although MgcRacGAP (Mgc) is required for spatially confined RhoA-GTP at the equatorial cortex of dividing cells, both the target specificity of Mgc's GAP activity and the involvement of phosphorylation of Mgc at Ser-386 are controversial. In addition, Mgc's function at cell–cell junctions remains unclear. Here, using gastrula-stage Xenopus laevis embryos as a model system, we examine Mgc's role in regulating localized RhoA-GTP and Rac1-GTP in the intact vertebrate epithelium. We show that Mgc's GAP activity spatially restricts accumulation of both RhoA-GTP and Rac1-GTP in epithelial cells—RhoA at the cleavage furrow and RhoA and Rac1 at cell–cell junctions. Phosphorylation at Ser-386 does not switch the specificity of Mgc's GAP activity and is not required for successful cytokinesis. Furthermore, Mgc regulates adherens junction but not tight junction structure, and the ability to regulate adherens junctions is dependent on GAP activity and signaling via the RhoA pathway. Together these results indicate that Mgc's GAP activity down-regulates the active populations of RhoA and Rac1 at localized regions of epithelial cells and is necessary for successful cytokinesis and cell–cell junction structure.
Lack of evidence for elevated CO2-induced bottom-up effects on marine copepods: a dinoflagellate–calanoid prey–predator pair
Authors: Isari Stamatina , Zervoudaki Soultana , Peters Janna , Papantoniou Georgia , Pelejero Carles , Saiz Enric
Published: May 2015

Rising levels of atmospheric CO2 are responsible for a change in the carbonate chemistry of seawater with associated pH drops (acidification) projected to reach 0.4 units from 1950 to 2100. We investigated possible indirect effects of seawater acidification on the feeding, fecundity, and hatching success of the calanoid copepod Acartia grani, mediated by potential CO2-induced changes in the nutritional characteristics of their prey. We used as prey the autotrophic dinoflagellate Heterocapsa sp., cultured at three distinct pH levels (control: 8.17, medium: 7.96, and low: 7.75) by bubbling pure CO2 via a computer automated system. Acartia grani adults collected from a laboratory culture were acclimatized for 3 d at food suspensions of Heterocapsa from each pH treatment (ca. 500 cells ml−1; 300 μg C l−1). Feeding and egg production rates of the preconditioned females did not differ significantly among the three Heterocapsa diets. Egg hatching success, monitored once per day for the 72 h, did not reveal significant difference among treatments. These results are in agreement with the lack of difference in the cellular stoichiometry (C : N, C : P, and N : P ratios) and fatty acid concentration and composition encountered between the three tested Heterocapsa treatments. Our findings disagree with those of other studies using distinct types of prey, suggesting that this kind of indirect influence of acidification on copepods may be largely associated with interspecific differences among prey items with regard to their sensitivity to elevated CO2 levels.
Introduction
Authors: Sadler John Z. , van Staden C.W. , Fulford K. W. M.
Published: May 2015

TheOxford Handbook of Psychiatric Ethicsis the most comprehensive treatment of the field in history. The editors briefly describe the goals, scope, and organization of the book. Major themes and the state of the field in the twenty-first century are then addressed. Psychiatric ethics is an excellent framework to examine social changes in psychiatry over the past 25 years. These include multiculturalism and its associated diversity of values; the transition to the digital era with new demands on confidentiality, clinical boundaries, and privacy; the empowerment of psychiatric service users as full participants and co-producers of care; the development of new technologies of assessment and treatment, varying in their invasiveness and risk; the recognition of expanded social roles for psychiatrists, and the associated virtues of psychiatric citizenship; and the development of new practice models, settings, participants, and oversight—representing profound challenges and opportunities for the ethical practice of psychiatry.
Ethical Issues in Mental Health Peer Support
Authors: Crepaz-Keay David , Cyhlarova Eva
Published: May 2015

This chapter identifies and explores three different models of peer support that are currently in widespread use. There is a brief review of the policy and practice context of peer support. The chapter explores and explains some of the language associated with peer support and some of the assumptions that this language implies. The nature of power relationship and its impact on peer support is considered. The three models of peer support are explored in detail, with a particular emphasis on the commonalities and differences between them, the motivation of those involved, and the underpinning values of each approach. The chapter concludes with a discussion on the nature of peer relationships and the characteristics that make people peers in the context of peer support.
Values-Based Assessment in Mental Health
Authors: Fulford K. W. M. , Duhig Lu , Hankin Julie , Hicks Joanna , Keeble Justine
Published: May 2015

This chapter describes philosophical and empirical work underpinning recent developments in values-based mental health assessment culminating in the 3 Keys to a Shared Approach, a UK-based project co-produced between service users and providers. Three aspects of values-based mental health assessment are described: person-centered, multidisciplinary, or strengths-based assessment. The central role of values in person-centered assessment is shown through the story of a real (biographically disguised) person and the interpretation of his story drawing on diagnostic manuals such as the DSM. Philosophical value theory suggests that values in psychiatric diagnosis reflect the diversity of our values as unique individuals. This diversity is addressed by values-based practice. The contribution of multidisciplinary teamwork to values-based assessment is then outlined as derived from the Models Project. Finally, the 3 Keys Project is described, concluding by pointing to the wider significance of the Project for mental health practice as a whole.
Introduction
Authors: Snyder James , Dishion Thomas J.
Published: May 2015

This chapter provides an introduction to the concept of coercion in human relationships. Coercion is defined as an interpersonal strategy that results in avoidance or escape of an aversive social experience. We describe the basic topographic, functional, and contextual factors associated with coercion. The varied ways in which coercive behaviors are manifested and operate in multiple social relationships are described, along with the kinds of social contingencies and conditions that grow coercive dynamics. The origins, shaping by social environmental experiences, and longer term outcomes of coercive behaviors and relationship dynamics are discussed from a developmental perspective. Research on coercion was inspired by an interest to design effective interventions. The dialectic between applied and basic research strengthens our scientific understanding of the role of coercive relationship dynamics in developmental outcomes and provides the basis for several evidenced-based interventions that improve the lives of children and families.