bluuebunny/crossref_metadata_2025 huggingface dataset:
PMMA-Augmentation von Pedikelschrauben: Ergebnisse einer Umfrage in Deutschland
Authors: Goost H. , Kabir K. , Wirtz D. , Deborre C. , Karius T. , Pflugmacher R. , Koch E. , Burger C. , Fölsch C.
Published: June 2012

Hintergrund: Im Rahmen einer Fachärztebefragung sollte die aktuelle Praxis der Zementaugmentation von Pedikelschrauben erkundet werden. Material und Methode: Anlässlich des Deutschen Wirbelsäulenkongresses 2009 wurden die Teilnehmer auf einen Umfragedienst im Internet aufmerksam gemacht. Der Fragebogen bezog sich auf unterschiedliche Aspekte zu Materialien und Verfahren bei der Pedikelschraubenaugmentation und wurde anonym ausgefüllt. Zur Auswertung wurden die Häufigkeiten entsprechender Antworten unterteilt nach den Facharztgruppen Orthopädie und Unfallchirurgie vs. Neurochirurgen ausgezählt und in Prozent umgerechnet. Für die Gruppenvergleiche wurde der Mantel-Haenszel-Test angewandt. Ergebnisse und Schlussfolgerung: 108 Fragebogen konnten ausgewertet werden. Es beteiligten sich zu 64 % Orthopäden/Chirurgen und zu 36 % Neurochirurgen. 78,5 % der Befragten gaben an, dass sie zementaugmentierte Pedikelschrauben verwenden. Etwa ⅔ der Fachärzte verwenden für die Zementaugmentation kanülierte Schrauben oder weitere spezielle Schrauben; etwa 20 % verbinden das Einsetzen der Schrauben mit einer Kyphoplastie oder Vertebroplastie, wobei die Expedium-Schrauben besonders bevorzugt werden. Am häufigsten wird als Instrumentarium die Ballon-Kyphoplastie eingesetzt. Hinsichtlich der wichtigsten Indikationen für die Pedikelschraubenaugmentation stehen die Osteoporose, der intraoperative Befund sowie der vorherige Schraubenausbruch bzw. die Revisionsoperation im Vordergrund, wobei viele Mehrfachnennungen registriert wurden. Als Komplikationen beobachteten die Anwender am häufigsten Zementaustritte in den Spinalkanal (28 %). Die Kostenfrage wurde von den meisten Befragten als wichtig angesehen, wobei die entsprechende Kodierung und der mögliche Erlös bei etwa ⅔ der Teilnehmer unbekannt war. Es kann davon ausgegangen werden, dass der Einsatz von Pedikelschrauben in Deutschland in den entsprechenden Fachbereichen weitgehend etabliert ist, ohne dass sich bisher ein Verfahren oder eine Kombination durchgesetzt hat.
Evidenzbasierte Knorpeltherapie im Kniegelenk – regenerative Behandlungsoptionen
Authors: Proffen B. , von Keudell A. , Vavken P.
Published: June 2012

Hintergrund: In den vergangenen Jahren konnte ein Wandel in der Behandlung von Knorpeldefekten, weg vom Ersatz, hin zu regenerativen Ansätzen, beobachtet werden. Zwei sehr populäre regenerative Ansätze sind zum einen die autologe Chondrozytenimplantation (ACI) und zum anderen die Mikrofrakturierung. Material und Methoden: Das Ziel dieser Übersichtsarbeit ist es, diese beiden Methoden zu beschreiben, zu vergleichen und einen evidenzbasierten Algorithmus für die Behandlung fokaler Knorpeldefekte zu präsentieren. Ergebnisse: Beide Behandlungsweisen bewiesen ihre Effektivität in Langzeitstudien, in denen die Mikrofrakturierung bei bis zu 95 % der Patienten und die ACI in den Nachuntersuchungen nach 5 bzw. 2–9 Jahren bei 92 % der Patienten eine Verbesserung bewirkte. Zu den Faktoren, die den Behandlungserfolg entscheidend beeinflussen, gehören unter anderem die Defektlokalisation, Begleiterkrankungen und das Alter der Patienten. Zu den Komplikationen bei der Mikrofrakturierung zählen die minderwertige Gewebedifferenzierung und die Osteophytenbildung in der Behandlungszone, bei der ACI die Gewebehypertrophie und der notwendige zweizeitige Eingriff. In vergleichenden Studien ergibt sich klinisch ein weitgehend ähnliches Bild, jedoch scheint die ACI histologisch etwas bessere Ergebnisse zu ergeben, was höchstwahrscheinlich zu besseren Langzeitergebnissen führt. Schlussfolgerung: Zwar besteht noch kein allgemeines Konzept für die Herangehensweise an Knorpelschäden im Kniegelenk, doch empfiehlt sich aufgrund der aktuellen Studienergebnisse eine auf der Defektgröβe basierende Therapiewahl.
Locking Attachment Plate – Erste Erfahrungen
Authors: Dumpies C. , Conrad T. , Marintschev I. , Hofmann G.
Published: June 2012

Hintergrund: In dieser Arbeit stellen wir unsere ersten Erfahrungen in der Anwendung einer neuen, winkelstabilen Plattenosteosynthese vor: Locking Attachment Plate (LAP, Fa. Synthes, Oberdorf, Schweiz). Wir prüften, ob die LAP eine sinnvolle Ergänzung in der bisherigen technischen Versorgung periprothetischer Frakturen darstellt. Die LAP wird bei periprothetischen Frakturen mit stabil einliegender Endoprothese bzw. Frakturen um intramedulläre Implantate angewandt. Die Plattenosteosynthese wird z. B. auf eine 4,5-mm Locking Compression Plate (LCP) installiert. Über ihre 4 diagonal angebrachten Arme können Verriegelungs- oder Kortikalisschrauben winkelstabil, bikortikal um den Prothesenschaft in den Knochen eingebracht werden. Die LAP soll den lateralen Schraubenausbruch verhindern, den Prothesenschaft stabilisieren und somit die frühzeitige postoperative Mobilisierung der Patienten ermöglichen. Patienten und Methoden: Wir implantierten die LAP mittels operativer Frakturbehandlung in ORIF-Technik bei 17 Patienten mit periprothetischen Frakturen an Femur, Tibia und Humerus. Der Nachbeobachtungszeitraum betrug mindestens 13 Monate. Ergebnisse: Es entgingen 2 Patienten der Verlaufsbeobachtung, da sie wenige Wochen postoperativ aufgrund ihrer Begleitmorbiditäten starben. Insgesamt kam es in 2 von 17 Fällen zum Infektgeschehen (11,8 %). Es wurden 15 Patienten nachuntersucht. Davon erlangten 11 Patienten ihren ursprünglichen Bewegungsumfang (ROM) und 9 Patienten ihre Ausgangsmobilität wieder. Alle Patienten mit periprothetischen Humerusfrakturen verzeichneten muskuläre Defizite. In 5 von 15 Fällen (33,3 %) konnte zumindest radiologisch keine Frakturheilung festgestellt werden. Dennoch lag bei 14 von 15 Patienten das Implantat stabil ein, ohne Zeichen einer Implantat- oder Prothesenlockerung. Es trat kein Fall von Materialversagen auf. Schlussfolgerung: Periprothetische Frakturen sind eine immer häufiger werdende Komplikation beim alten, oft multimorbiden Patienten. Eine rasche therapeutische Intervention und die frühzeitige postoperative Mobilisierung tragen entscheidend zum Behandlungserfolg bei. Die ersten Ergebnisse in der Anwendung der LAP als neues Implantat zur Versorgung periprothetischer Frakturen an Femur, Tibia und Humerus sind vielversprechend. Es bedarf weiterer Studien, um zu zeigen, ob unsere insgesamt guten Ergebnisse in größeren Patientenkollektiven reproduzierbar sind und die LAP einen festen Stellenwert im technischen Repertoire zur Therapie periprothetischer Frakturen einnehmen kann.
Avoiding Complications of Microtia and Otoplasty
Authors: Romo Thomas , Baratelli Roxana , Raunig Hermann
Published: June 2012

Congenital ear surgery constitutes one of the most challenging reconstructive procedures in plastic surgery secondary to the complex architecture of the auricle and the multiple factors involved in the reconstructive techniques. The most common complications encountered during microtia repair and otoplasty are described. Emphasis is placed on preventing these complications.
Three unequal masses on a ring and soft triangular billiards
Authors: Oliveira H. A. , Emidio G. A. , Beims M. W.
Published: June 2012

The dynamics of three soft interacting particles on a ring is shown to correspond to the motion of one particle inside a soft triangular billiard. The dynamics inside the soft billiard depends only on the masses ratio between particles and softness ratio of the particles interaction. The transition from soft to hard interactions can be appropriately explored using potentials for which the corresponding equations of motion are well defined in the hard wall limit. Numerical examples are shown for the soft Toda-like interaction and the error function.
Resonances within chaos
Authors: Gallavotti G. , Gentile G. , Giuliani A.
Published: June 2012

A chaotic system under periodic forcing can develop a periodically visited strange attractor. We discuss simple models in which the phenomenon, quite easy to see in numerical simulations, can be completely studied analytically.
Chaotic and Arnold stripes in weakly chaotic Hamiltonian systems
Authors: Custódio M. S. , Manchein C. , Beims M. W.
Published: June 2012

The dynamics in weakly chaotic Hamiltonian systems strongly depends on initial conditions (ICs) and little can be affirmed about generic behaviors. Using two distinct Hamiltonian systems, namely one particle in an open rectangular billiard and four particles globally coupled on a discrete lattice, we show that in these models, the transition from integrable motion to weak chaos emerges via chaotic stripes as the nonlinear parameter is increased. The stripes represent intervals of initial conditions which generate chaotic trajectories and increase with the nonlinear parameter of the system. In the billiard case, the initial conditions are the injection angles. For higher-dimensional systems and small nonlinearities, the chaotic stripes are the initial condition inside which Arnold diffusion occurs.
Chaos in the square billiard with a modified reflection law
Authors: Del Magno Gianluigi , Lopes Dias João , Duarte Pedro , Pedro Gaivão José , Pinheiro Diogo
Published: June 2012

The purpose of this paper is to study the dynamics of a square billiard with a non-standard reflection law such that the angle of reflection of the particle is a linear contraction of the angle of incidence. We present numerical and analytical arguments that the nonwandering set of this billiard decomposes into three invariant sets, a parabolic attractor, a chaotic attractor, and a set consisting of several horseshoes. This scenario implies the positivity of the topological entropy of the billiard, a property that is in sharp contrast with the integrability of the square billiard with the standard reflection law.
Classification of symmetric periodic trajectories in ellipsoidal billiards
Authors: Casas Pablo S. , Ramírez-Ros Rafael
Published: June 2012

We classify nonsingular symmetric periodic trajectories (SPTs) of billiards inside ellipsoids of Rn+1 without any symmetry of revolution. SPTs are defined as periodic trajectories passing through some symmetry set. We prove that there are exactly 22n(2n+1-1) classes of such trajectories. We have implemented an algorithm to find minimal SPTs of each of the 12 classes in the 2D case (R2) and each of the 112 classes in the 3D case (R3). They have periods 3, 4, or 6 in the 2D case and 4, 5, 6, 8, or 10 in the 3D case. We display a selection of 3D minimal SPTs. Some of them have properties that cannot take place in the 2D case.
Lorentz process with shrinking holes in a wall
Authors: Nándori Péter , Szász Domokos
Published: June 2012

We ascertain the diffusively scaled limit of a periodic Lorentz process in a strip with an almost reflecting wall at the origin. Here, almost reflecting means that the wall contains a small hole waning in time. The limiting process is a quasi-reflected Brownian motion, which is Markovian, but not strong Markovian. Local time results for the periodic Lorentz process, having independent interest, are also found and used.
A three-state effective Hamiltonian for symmetric cationic diarylmethanes
Authors: Olsen Seth , McKenzie Ross H.
Published: June 2012

We analyze the low-energy electronic structure of a series of symmetric cationic diarylmethanes, which are bridge-substituted derivatives of Michler's Hydrol Blue. We use a four-electron, three-orbital complete active space self-consistent field and multi-state multi-reference perturbation theory model to calculate a three-state diabatic effective Hamiltonian for each dye in the series. We exploit an isolobal analogy between the active spaces of the self-consistent field solutions for each dye to represent the electronic structure in a set of analogous diabatic states. The diabatic states can be identified with the bonding structures in classical resonance-theoretic models of cyanine dyes. We identify diabatic states with opposing charge and bond-order localization, analogous to the classical resonance structures, and a third state with charge on the bridge. While the left- and right-charged structures are similar for all dyes, the structure of the bridge-charged diabatic state, and the Hamiltonian matrix elements connected to it, change significantly across the series. The change is correlated with an inversion of the sign of the charge carrier on the bridge, which changes from an electron pair to a hole as the series is traversed.
The interaction between two planar and nonplanar quantum electron acoustic solitary waves in dense electron-ion plasmas
Authors: EL-Labany S. K. , EL-Shamy E. F. , El-Mahgoub M. G.
Published: June 2012

The interaction between two planar and nonplanar (cylindrical and spherical) quantum electron acoustic solitary waves (QEASWs) in quantum dense electron-ion plasmas has been studied. The extended Poincaré-Lighthill-Kuo method is used to obtain planar and nonplanar phase shifts after the interaction of the two QEASWs. The change of phase shifts and trajectories for QEASWs due to the effect of the different geometries, the quantum corrections of diffraction, and the cold electron-to-hot electron number density ratio are discussed. It is shown that the interaction of the QEASWs in planar geometry, cylindrical geometry, and spherical geometry are different. The present investigation may be beneficial to understand the interaction between two planar and nonplanar QEASWs that may occur in the quantum plasmas found in laser-produced plasmas as well as in astrophysical plasmas.
Transferable pair potentials for CdS and ZnS crystals
Authors: Grünwald Michael , Zayak Alexey , Neaton Jeffrey B. , Geissler Phillip L. , Rabani Eran
Published: June 2012

A set of interatomic pair potentials is developed for CdS and ZnS crystals. We show that a simple energy function, which has been used to describe the properties of CdSe [E. Rabani, J. Chem. Phys. 116, 258 (2002)]10.1063/1.1424321, can be parametrized to accurately describe the lattice and elastic constants, and phonon dispersion relations of bulk CdS and ZnS in the wurtzite and rocksalt crystal structures. The predicted coexistence pressure of the wurtzite and rocksalt structures as well as the equation of state are in good agreement with experimental observations. These new pair potentials enable the study of a wide range of processes in bulk and nanocrystalline II–VI semiconductor materials.
Raman spectroscopy of optically levitated supercooled water droplet
Authors: Suzuki Hidenori , Matsuzaki Yoshiki , Muraoka Azusa , Tachikawa Maki
Published: June 2012

By use of an optical trap, we can levitate micrometer-sized drops of purified water and cool them below the melting point free from contact freezing. Raman spectra of the OH stretching band were obtained from those supercooled water droplets at temperatures down to −35 °C. According to the two-state model, an enthalpy change due to hydrogen-bond breaking is derived from temperature dependence of the spectral profile. The isobaric heat capacity calculated from the enthalpy data shows a sharp increase as the temperature is lowered below −20 °C in good agreement with conventional thermodynamic measurements.
The impact of the lattice symmetry and the inclusion shape on the spectrum of 2D magnonic crystals
Authors: Kłos J. W. , Sokolovskyy M. L. , Mamica S. , Krawczyk M.
Published: June 2012

We investigate spin waves in two-dimensional superlattices in the form of an infinite ferromagnetic slab of finite thickness with periodically embedded ferromagnetic inclusions. One of the reasons of the interest in magnonic superlattices is the possibility of tailoring their spectrum to produce magnonic gaps, crucial for the prospective applications. The objective of this study is to find the optimal values of structural parameters for which low-frequency magnonic gaps will occur and have a maximum width. We provide some guidelines for designing superlattices with a desired spectrum. We focus on the role of the symmetry of the lattice versus other geometrical factors, including the filling fraction and the superlattice constant. We compare the spectra of superlattices with inclusions of circular, hexagonal, and square cross sections.
Characteristics of tsunami motion and energy budget during runup and rundown processes over a plane beach
Authors: Zhao Xi , Wang Benlong , Liu Hua
Published: June 2012

Motions of tsunami waves during runup and rundown processes on the uniform sloping beach are studied numerically by the fully nonlinear and highly dispersive Boussinesq equations. We first study the leading-depression N-wave defined by solitary theory. The shoreline movement and its moving speed are analyzed during the wave approaching the coastal area. Details on the flow field and the energy transformation are obtained in terms of the reconstruction of the full velocity field by Boussinesq equations. In addition, solitary wave is studied as a comparison. The different energy budget explains the phenomenon that the N-wave leads much larger runup than the solitary wave in some specific situations. The investigation is then extended to the patterns of the energy transformation of N-shape waves, hump-like waves, and sinusoidal long waves. These waves are of the same order in scale with the recent giant tsunamis. The results show that the potential energy of the N-shape tsunami waves nearly reaches the maximum while that of the hump-like tsunami waves does not reach the maximum at the maximum runup, meanwhile the kinetic energy of both waves does not go to zero. For the sinusoidal wave train, however, its potential energy reaches the maximum and its kinetic energy goes to zero exactly at the maximum runup. To understand the responses caused by the variation of the waveforms, effects of the nonlinearity and the dispersion on the energy budget are studied in the geophysical tsunamis order. Moreover, the regularities of the energy budget of some general cases including the leading-depression N-waves (LDNs), the leading-elevation N-wave, and generalized LDNs are investigated extensively. The mechanism of the energy budget of these waves is quite different as just considering the potential energy at the maximum runup.
Pattern-integrated interference lithography instrumentation
Authors: Burrow G. M. , Leibovici M. C. R. , Kummer J. W. , Gaylord T. K.
Published: June 2012

Multi-beam interference (MBI) provides the ability to form a wide range of sub-micron periodic optical-intensity distributions with applications to a variety of areas, including photonic crystals (PCs), nanoelectronics, biomedical structures, optical trapping, metamaterials, and numerous subwavelength structures. Recently, pattern-integrated interference lithography (PIIL) was presented as a new lithographic method that integrates superposed pattern imaging with interference lithography in a single-exposure step. In the present work, the basic design and systematic implementation of a pattern-integrated interference exposure system (PIIES) is presented to realize PIIL by incorporating a projection imaging capability in a novel three-beam interference configuration. A fundamental optimization methodology is presented to model the system and predict MBI-patterning performance. To demonstrate the PIIL method, a prototype PIIES experimental configuration is presented, including detailed alignment techniques and experimental procedures. Examples of well-defined PC structures, fabricated with a PIIES prototype, are presented to demonstrate the potential of PIIL for fabricating dense integrated optical circuits, as well as numerous other subwavelength structures.
Electronic properties of the Cu2ZnSn(Se,S)4 absorber layer in solar cells as revealed by admittance spectroscopy and related methods
Authors: Gunawan Oki , Gokmen Tayfun , Warren Charles W. , Cohen J. David , Todorov Teodor K. , Barkhouse D. Aaron R. , Bag Santanu , Tang Jiang , Shin Byungha , Mitzi David B.
Published: June 2012

Admittance spectra and drive-level-capacitance profiles of several high performance Cu2ZnSn(Se,S)4 (CZTSSe) solar cells with bandgap ∼1.0–1.5 eV are reported. In contrast to the case for Cu(In,Ga)(S,Se)2, the CZTSSe capacitance spectra exhibit a dielectric freeze out to the geometric capacitance plateau at moderately low frequencies and intermediate temperatures (120–200 K). These spectra reveal important information regarding the bulk properties of the CZTSSe films, such as the dielectric constant and a dominant acceptor with energy level of 0.13–0.2 eV depending on the bandgap. This deep acceptor leads to a carrier freeze out effect that quenches the CZTSSe fill factor and efficiency at low temperatures.
Improved sensing performance of polycrystalline-silicon based dual-gate ion-sensitive field-effect transistors using high-k stacking engineered sensing membrane
Authors: Jang Hyun-June , Bae Tae-Eon , Cho Won-Ju
Published: June 2012

Improved sensing performance, larger pH sensitivity that breaches the Nernst response limit with excellent stability, was realized on polycrystalline silicon based dual-gate (DG) ion-sensitive field-effect transistors. The capacitive coupling between the top and bottom gate oxides for a DG operation amplified its sensitivity to as high as 325.8 mV/pH. In particular, the SiO2/HfO2/Al2O3 (OHA) layer, proposed as an engineered sensing membrane, significantly reinforced the sensing margin of devices as well as the chemical stability for long-term use. The sensing characteristics of the OHA and conventional SiO2 layer were evaluated for single gate and DG operation modes, respectively.
Determination of conduction band offset between strained CdSe and ZnSe layers using deep level transient spectroscopy
Authors: Rangel-Kuoppa Victor-Tapio
Published: June 2012

The conduction band offset between strained CdSe layers embedded in unintentionally n-type doped ZnSe is measured using deep level transient spectroscopy and reported. The activation energy for electrons in three monolayers thin ultra thin quantum wells (UTQWs) is obtained, with a value of 223 ± 10 meV. This corresponds to an UTQW barrier height (the conduction band offset) between 742 meV and 784 meV. These values show that the band gap misfit between strained CdSe and ZnSe is around 70% to 74% in the conduction band.
Multifunctional magnetic rotator for micro and nanorheological studies
Authors: Tokarev Alexander , Aprelev Alexey , Zakharov Mikhail N. , Korneva Guzeliya , Gogotsi Yury , Kornev Konstantin G.
Published: June 2012

We report on the development of a multifunctional magnetic rotator that has been built and used during the last five years by two groups from Clemson and Drexel Universities studying the rheological properties of microdroplets. This magnetic rotator allows one to generate rotating magnetic fields in a broad frequency band, from hertz to tens kilohertz. We illustrate its flexibility and robustness by conducting the rheological studies of simple and polymeric fluids at the nano and microscale. First we reproduce a temperature-dependent viscosity of a synthetic oil used as a viscosity standard. Magnetic rotational spectroscopy with suspended nickel nanorods was used in these studies. As a second example, we converted the magnetic rotator into a pump with precise controlled flow modulation. Using multiwalled carbon nanotubes, we were able to estimate the shear modulus of sickle hemoglobin polymer. We believe that this multifunctional magnetic system will be useful not only for micro and nanorheological studies, but it will find much broader applications requiring remote controlled manipulation of micro and nanoobjects.
Dielectrophoretically structured piezoelectric composites with high aspect ratio piezoelectric particles inclusions
Authors: van den Ende D. A. , van Kempen S. E. , Wu X. , Groen W. A. , Randall C. A. , van der Zwaag S.
Published: June 2012

Piezoelectric composites were prepared by dielectrophoretic alignment of high aspect ratio piezoelectric particles in a thermosetting polymer matrix. A high level of alignment was achieved in the cured composite from a resin containing randomly oriented high aspect ratio particles. Upon application of an electric field during curing of the resin, the particles were found to rotate with their long axes in the direction of the electric field, before coalescing to form chains. The dielectric and piezoelectric properties of the structured composites are well described by an analytical model for composites containing particles arranged into chains. The influence of degree of rotation and aspect ratio of the individual particles as well as their spacing is described with this model. The results correlate with the experimental values for both permittivity and piezoelectric constants in the poling direction. Dielectric and piezoelectric properties were significantly improved with respect to randomly dispersed piezoelectric ceramic powder–polymer composites and the maximum g33 was shifted to a lower volume fraction. The results could have implications for development of dielectric and piezoelectric (nano-)fiber composites for dielectrics such as embedded capcitors, as well as piezoelectrics for sensing and energy harvesting applications.
Enhancement of the Purcell effect for colloidal CdSe/ZnS quantum dots coupled to silver nanowires by a metallic tip
Authors: Wang Y. C. , Yuan C. T. , Kuo M. Y. , Wu M. C. , Tang Jau , Shih M. H.
Published: June 2012

In this study, the Purcell effect for CdSe/ZnS quantum dots emission coupled to a silver nanowire cavity was investigated. We manipulated the interaction between colloidal quantum dots (QDs) and an Ag NW in the presence of a metallic tip. When a metal tip approaches the Ag NW, the Ag surface plasmon mode could be lifted away from the metallic NW so that a low optical loss could still be obtained. This work demonstrates enhancement of the spatial coupling between the plasmonic mode and light sources and reduction in metal Ohmic losses, resulting in an enhanced Purcell effect and coupling efficiency accompanied with increased fluorescence intensity.
Exact nonlinear excitations in double-degenerate plasmas
Authors: Akbari-Moghanjoughi M.
Published: June 2012

In this work, we use the conventional hydrodynamics formalism and incorporate the Chew-Goldberger-Low double-adiabatic theory to evaluate the nonlinear electrostatic ion excitations in double-degenerate (electron spin-orbit degenerate) magnetized quantum plasmas. Based on the Sagdeev pseudopotential method, an exact general pseudopotential is calculated which leads to the allowed Mach-number range criteria for such localized density structures in an anisotropic magnetized plasma. We employ the criteria on the Mach-number range for diverse magnetized quantum plasma with different equations of state. It is remarked that various plasma fractional parameters such as the system dimensionality, ion-temperature, relativistic-degeneracy, Zeeman-energy, and plasma composition are involved in the stability of an obliquely propagating nonlinear ion-acoustic wave in a double-degenerate quantum plasma. Current study is most appropriate for nonlinear wave analysis in dense astrophysical magnetized plasma environments such as white-dwarfs and neutron-star crusts where the strong magnetic fields can be present.
Multiple silicon nanowire complementary tunnel transistors for ultralow-power flexible logic applications
Authors: Lee M. , Jeon Y. , Jung J.-C. , Koo S.-M. , Kim S.
Published: June 2012

Based on experimental and simulation studies to gain insight into the suppression of ambipolar conduction in two distinct tunnel field-effect transistor (TFET) devices (that is, an asymmetric source-drain doping or a properly designed gate underlap), here we report on the fabrication and electrical/mechanical characterization of a flexible complementary TFET (c-TFET) inverter on a plastic substrate using multiple silicon nanowires (SiNWs) as the channel material. The static voltage transfer characteristic of the SiNW c-TFET inverter exhibits a full output voltage swing between 0 V and Vdd with a high voltage gain of ∼29 and a sharp transition of 0.28 V at Vdd = 3 V. A leakage power consumption of the SiNW c-TFET inverter in the standby state is as low as 17.1 pW for Vdd = 3 V. Moreover, its mechanical bendability indicates that it has good fatigue properties, providing an important step towards the realization of ultralow-power flexible logic circuits.
Solution processed LiF anode modification for polymer solar cells
Authors: Turak Ayse , Aytun Taner , Ow-Yang Cleva W.
Published: June 2012

The indium-tin-oxide/active layer interface is critical to the performance of organic solar cell devices. In this study, submonolayer films of LiF nanoparticles are deposited on the electrode surface with the assistance of polymeric micelle reactors, with controlled nanoscale surface coverage. Incorporation of the solution-processed bi-layer electrodes into a conventional poly(3-hexyl-thiophene): [6,6]-phenyl C61-butyric acid methyl ester device shows significant improvement in device performance, especially when used in combination with a poly(3,4-ethylenedioxythiophene: poly(styrene sulfonate) layer. The nearly 5× improvement in the short circuit current and decrease in the contact resistance is mostly likely related to the increase in surface work function from the use of LiF nanoparticles. The results strongly indicate that engineering of the interfaces is a useful tool for future device optimization.
Plasma-wall interaction in Hall thrusters with magnetic lens configuration
Authors: Brieda Lubos , Keidar Michael
Published: June 2012

Some recently developed Hall thrusters utilize a magnetic field configuration in which the field lines penetrate the thruster walls at a high incidence angle. This so-called magnetic lens leads to an electric field pointing away from the walls, which is expected to reduce ion losses and improve thruster efficiency. This configuration also introduces an interesting behavior in the sheath formation. At sufficiently large angles, ions are repelled from the wall, and sheath collapse is expected. We use a plasma simulation code to investigate this phenomenon in detail. We consider the role of the magnetic field incidence angle, secondary electron emission, and a magnetic mirror. Numerical study confirms the theoretical predictions, and at large angles, ions are seen to turn away from the wall. We also consider the role of the magnetic field geometry on ion wall flux and channel erosion, and observe reduction in both quantities as the magnetic field incidence angle is increased.
Bragg resonances of magnetostatic surface spin waves in a layered structure: Magnonic crystal-dielectric-metal
Authors: Beginin E. N. , Filimonov Yu. A. , Pavlov E. S. , Vysotskii S. L. , Nikitov S. A.
Published: June 2012

It is experimentally shown that metal cladding of the surface of a one-dimensional magnonic crystal destroys the Bragg band gaps in microwave transmission spectra of propagating magnetostatic surface spin waves in magnonic crystal. This is a consequence of violating a phase synchronism condition of forward and reflected by a magnonic crystal magnetostatic surface wave. When a magnetostatic surface wave propagates in a layered structure, ferromagnetic film with a magnonic crystal-dielectric layer-metal cladding this synchronism condition can also be fulfilled, not depending on the thickness of a dielectric layer.
Analyzing cooking fuel and stove choices in China till 2030
Authors: Mainali Brijesh , Pachauri Shonali , Nagai Yu
Published: June 2012

Many people in China still burn low grade solid fuels in traditional stoves to meet their cooking and heating energy demands. This results in significant pollution, affecting the health of especially women and children who are exposed most. The mode of energy consumption and types of stoves in use may change with increasing prosperity. Product specific and socio-economic parameters also influence these choices. We analyze cooking fuel and stove choices in China. Choices are modeled to depend on standard economic variables such as income, technology costs, and fuel prices, along with some variables unique to the developing country setting such as inconvenience costs. Our analysis shows that 24% of the rural and 17% of the urban population will still depend on solid fuels in 2030 under a business as usual scenario. Various policy scenarios that can accelerate transition to modern fuels by 2030 are also analyzed in this paper and their costs, energy, emissions and health impacts assessed.
Systemwide Evaluation of Avian Predation on Juvenile Salmonids from the Columbia River Based on Recoveries of Passive Integrated Transponder Tags
Authors: Evans Allen F. , Hostetter Nathan J. , Roby Daniel D. , Collis Ken , Lyons Donald E. , Sandford Benjamin P. , Ledgerwood Richard D. , Sebring Scott
Published: June 2012

We recovered passive integrated transponder (PIT) tags from nine piscivorous waterbird colonies in the Columbia River basin to evaluate avian predation on Endangered Species Act (ESA)‐listed salmonid Oncorhynchus spp. populations during 2007–2010. Avian predation rates were calculated based on the percentage of PIT‐tagged juvenile salmonids that were detected as passing hydroelectric dams and subsequently were consumed and deposited by birds on their nesting colonies. Caspian terns Hydroprogne caspia (hereafter, “terns”) and double‐crested cormorants Phalacrocorax auritus (hereafter, “cormorants”) nesting on East Sand Island in the Columbia River estuary consumed the highest proportions of available PIT‐tagged salmonids, with minimum predation rates ranging from 2.5% for Willamette River spring Chinook salmon O. tshawytscha to 16.0% for Snake River steelhead O. mykiss. Estimated predation rates by terns, cormorants, gulls of two species (California gull Larus californicus and ring‐billed gull L. delawarensis), and American white pelicans Pelecanus erythrorhynchos nesting near the confluence of the Snake and Columbia rivers were also substantial; minimum predation rates ranged from 1.4% for Snake River fall Chinook salmon to 13.2% for upper Columbia River steelhead. Predation on ESA‐listed salmonids by gulls and American white pelicans were minor (<2.0% per ESA‐listed salmonid population) relative to predation by terns and cormorants. Cumulative impacts were greater for Snake River and upper Columbia River salmonids than for salmonids originating closer to the estuary because upriver salmonids must migrate past more bird colonies to reach the ocean. Predation rates adjusted for colony size (per capita rates) were significantly higher for terns and cormorants nesting at inland colonies (upstream of Bonneville Dam) than for those nesting in the estuary, suggesting that inland colonies have a greater reliance on salmonids as a food source. Management actions to increase salmonid survival by reducing avian predation in the estuary could be offset if birds that disperse from the estuary relocate to inland nesting sites on or near the Columbia River.
Counsellors' perceptions of client progression when working with clients who intentionally self‐harm and the impact such work has on the therapist
Authors: Fleet Doreen , Mintz Rita
Published: June 2012

Introduction: This paper describes a qualitative study focusing on counsellors' perceptions of client progression when working with clients who intentionally self‐harm and the impact this has on the therapist. Method: Semi‐structured interviews were employed and the constant comparative method utilised to analyse the data. Findings: Findings indicate that counsellors experience intense emotions in response to self‐harm including: shock; sadness; anxiety; anger; and frustration. Counsellors also struggled to manage the tension between multiple dualities, corresponding to professional opinions of a seemingly polar opposite nature. Although participants indicated a requirement to work in a client‐led way, they all had either an explicit or implicit agenda for change. These two conflicting states create a tension for a counsellor that is difficult to resolve. In addition there were various views of client progression, yet all participants agreed that progression was not simply about stopping self‐harm. Conclusion: There is a significant impact on the counsellor when working with clients who intentionally self‐harm and the complexity of the phenomenon appears to exacerbate their anxiety. Implications: Further research within the counselling field focusing on the ambiguous nature of the subject may increase understanding, which in turn may contribute to greater therapist efficacy when working with this client group.
Angle-resolved photoemission study of Fe3O4(0 0 1) films across Verwey transition
Authors: Ran Fan-Yong , Tsunemaru Yasushi , Hasegawa Takahide , Takeichi Yasuo , Harasawa Ayumi , Yaji Koichiro , Kim Sunghun , Kakizaki Akito
Published: June 2012

The valence band structure of well-ordered Fe3O4(0 0 1) films was investigated in situ by angle-resolved photoemission spectroscopy (ARPES) at room temperature (RT) and 90 K. A band gap of about 70 meV below the Fermi level (E
F) can be observed at 90 K, suggesting a ‘metal–insulator’ transition. With temperature reduced from RT to 90 K, O 2p-derived features shown in ARPES spectra change substantially. Meanwhile, the feature near E
F of the Fe3O4(0 0 1) film at 90 K becomes about 0.1 eV deeper than that at RT. The results are compared with recent theoretical studies.
Diameter-speed relation of sprite streamers
Authors: Kanmae T , Stenbaek-Nielsen H C , McHarg M G , Haaland R K
Published: June 2012

Propagation and splitting of sprite streamers has been observed at high temporal and spatial resolution using two intensified high-speed CMOS cameras recording at 10 000 and 16 000 frames per second. Concurrent video recordings from a remote site provided data for triangulation allowing us to determine accurate altitude scales for the sprites. Diameters and speeds of the sprite streamers were measured from the high-speed images, and the diameters were scaled to the reduced diameters based on the triangulated locations. The sprite streamers with larger reduced diameter move faster than those with smaller diameter; the relation between the reduced diameter and speed is roughly linear. The reduced diameters at ≈65–70 km altitude are larger than streamer diameters measured at ground pressure in laboratory discharges indicating a deviation from the similarity law possibly due to the effects of the photoionization and an expansion of the streamer head along its propagation over a long distance. The reduced diameter and speed of the sprite streamers agree well with the diameter–velocity relation proposed by Naidis (2009 Phys. Rev. E 79 057401), and the peak electric field of the sprite streamers is estimated to be approximately 3–5 times the breakdown threshold field.
Electric field measurement in a DBD in helium and helium–hydrogen mixture
Authors: Ivković S S , Obradović B M , Kuraica M M
Published: June 2012

Time–space-resolved optical emission spectroscopy was used for the investigation of a diffuse dielectric barrier discharge (DBD) in helium and in 95%He + 5%H2 gas mixture. The DBD in helium was diffuse in the whole range of the applied voltage, while in the gas mixture the discharge operated in diffuse mode only in the regime with more than three current peaks. In the helium discharge, the excitation of hydrogen H
β
is delayed compared with the excitation of the helium atomic line, while in the gas mixture both lines are excited simultaneously. Using the Stark polarization spectroscopy technique based on the He I 492.19 nm line and its forbidden counterpart, the electric field distribution (EFD) was measured in the cathode region of the DBD in helium and in the helium–hydrogen mixture. Electric field space distributions in both gas discharges, obtained at 20 kPa pressure, showed linear decreasing in the cathode region, which is a typical characteristic of the glow discharge. Linear fits of the EFDs showed that the length of the cathode fall region is smaller in the gas mixture than in pure helium. In the multiple current peak mode of the DBD, EFD was measured during each of the three current peaks and no noticeable difference between them is observed.
ITO electrode/photoactive layer interface engineering for efficient inverted polymer solar cells based on P3HT and PCBM using a solution-processed titanium chelate
Authors: Zhang Wenqing , Tan Zhan'ao , Qian Deping , Li Liangjie , Xu Qi , Li Shusheng , Zheng Hua , Li Yongfang
Published: June 2012

We report efficient inverted polymer solar cells (PSCs) based on poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) using alcohol-soluble titanium (diisopropoxide) bis (2,4-pentanedionate) (TIPD) as an electron selective layer between the indium tin oxide (ITO) electrode and the photoactive layer. The thermally annealed TIPD layer is highly transparent in the visible range and shows effective electron collection ability. By optimizing the electron-collecting layer, the photoactive layer and the hole-collecting layer, the power conversion efficiency (PCE) of the inverted device with the structure ITO/TIPD/P3HT : PCBM/MoO3/Ag reaches 4.10% under the illumination of AM1.5G, 100 mW cm−2, which is among the highest values for inverted PSCs based on P3HT : PCBM. The PCE of the inverted device is improved in comparison with the conventional device (3.77%) under the same experimental conditions.
Surface effect on the buckling of piezoelectric nanofilms
Authors: Zhang Jin , Wang Chengyuan , Adhikari Sondipon
Published: June 2012

A sandwich-plate model is developed to account for the effect of surface layers on the buckling of piezoelectric nanofilms (PNFs) due to an electrical voltage. The physical mechanisms of the surface effects are investigated and the contributions to the resultant effect are evaluated for surface piezoelectricity, surface stress and surface elasticity. It is found that the surface effect originates primarily from the residual surface stresses and enhanced piezoelectric coefficient due to the surface piezoelectricity. Its influence on the critical buckling voltage of a PNF depends sensitively on the thickness, the length-to-thickness ratio and the nature of residual surface stress. In addition, the intrinsic buckling may occur for a thin PNF where the relatively strong residual surface compression is achieved.
Enhanced formation of Ge nanocrystals in Ge : SiO2 layers by swift heavy ions
Authors: Antonova I V , Skuratov V A , Volodin V A , Smagulova S A , Marin D M , Janse van Vuuren A , Neethling J , Jedrzejewski J , Balberg I
Published: June 2012

In this paper we report the ability of swift heavy Xe ions with an energy of 480 MeV and a fluence of 1012 cm−2 to enhance the formation of Ge nanocrystals within SiO2 layers with variable Ge contents. These Ge-SiO2 films were fabricated by the co-sputtering of Ge and quartz sources which followed various annealing procedures. In particular, we found that the irradiation of the Ge : SiO2 films with subsequent annealing at 500 °C leads to the formation of a high concentration of nanocrystals (NCs) with a size of 2–5 nm, whereas without irradiation only amorphous inclusions were observed. This effect, as evidenced by Raman spectra, is enhanced by pre-irradiation at 550 °C and post-irradiation annealing at 600 °C, which also leads to the observation of room temperature visible photoluminescence.
Acoustic cloak/anti-cloak device with realizable passive/active metamaterials
Authors: Shen Huijie , Païdoussis Michael P. , Wen Jihong , Yu Dianlong , Cai Li , Wen Xisen
Published: June 2012

Utilizing the coordinate transformation method, together with exchange of variables between Maxwell's equations and the acoustic equations with axial-invariance in cylindrical coordinates, the acoustic parameters (anisotropic density and scalar bulk modulus) for an ideal cloak and an ideal anti-cloak are obtained. An anti-cloak allows the inside object to ‘see’ outside, but to be invisible from outside; whereas a cloak is invisible from outside, but ‘blind’ from inside. Utilizing a scattering algorithm developed in this paper, the pressure field calculation of the cloak/anti-cloak is performed and the concepts and characteristics of the acoustic cloak/anti-cloak are revisited. To be more easily achievable experimentally, a multilayered cloak/anti-cloak model with homogeneous isotropic materials is introduced, and its corresponding pressure distributions are calculated. Also, the total scattering cross-section curves for the multilayered cloak and anti-cloak over a certain frequency range are presented and compared. Finally, an active acoustic metamaterial made up of piezo-diaphragm cavity arrays is designed for the cloak/anti-cloak. Taking into account the coupling between adjacent cavity cells, a multi-control strategy for piezo-diaphragm cavity arrays is exploited, rendering possible wide ranges of effective densities and effective bulk moduli (or acoustic speeds), or even double-negative transformation medium (i.e. both density and bulk modulus parameters are negative). With such sets of active acoustic metamaterials, the cloak and anti-cloak may become both theoretically and experimentally realizable.
Cocycles on tropical varieties via piecewise polynomials
Authors: Francois Georges
Published: June 2012

We use piecewise polynomials to define tropical cocycles generalising the well-known notion of tropical Cartier divisors to higher codimensions. Groups of cocycles are tropical analogues of Chow cohomology groups. We also introduce an intersection product of cocycles with tropical cycles (the counterpart of the classical cap product) and prove that this gives rise to a Poincaré duality in some cases.
Curvature estimates for surfaces with bounded mean curvature
Authors: Bourni Theodora , Tinaglia Giuseppe
Published: June 2012

Estimates for the norm of the second fundamental form,

|

A

|

|A|

, play a crucial role in studying the geometry of surfaces in

R

3

\mathbb {R}^3

. In fact, when

|

A

|

|A|

is bounded the surface cannot bend too sharply. In this paper we prove that for an embedded geodesic disk with bounded

L
2

L^2

norm of

|

A

|

|A|

,

|

A

|

|A|

is bounded at interior points, provided that the

W

1
,
p

W^{1,p}

norm of its mean curvature is sufficiently small,

p
>
2

p>2

. In doing this we generalize some renowned estimates on

|

A

|

|A|

for minimal surfaces.
Cohomology algebra of plane curves, weak combinatorial type, and formality
Authors: Cogolludo Agustín J. , Matei D.
Published: June 2012

We determine an explicit presentation by generators and relations of the cohomology algebra

H
∗

(

P

2

∖

C

,

C

)

H^*(\mathbb {P}^2\setminus \mathcal {C},\mathbb {C})

of the complement to an algebraic curve

C

\mathcal {C}

in the complex projective plane

P

2

\mathbb {P}^2

via the study of log-resolution logarithmic forms on

P

2

\mathbb {P}^2

. As a first consequence, we derive that

H
∗

(

P

2

∖

C

,

C

)

H^*(\mathbb {P}^2\setminus \mathcal {C},\mathbb {C})

depends only on the following finite pieces of data: the number of irreducible components of

C

\mathcal {C}

together with their degrees and genera, the number of local branches of each component at each singular point, and the intersection numbers of every two distinct local branches at each singular point of

C

\mathcal {C}

. This finite set of data is referred to as the weak combinatorial type of

C

\mathcal {C}

. A further corollary is that the twisted cohomology jumping loci of

H
∗

(

P

2

∖

C

,

C

)

H^*(\mathbb {P}^2\setminus \mathcal {C},\mathbb {C})

containing the trivial character also depend on the weak combinatorial type of

C

\mathcal {C}

. Finally, the explicit construction of the generators and relations allows us to prove that complements of plane projective curves are formal spaces in the sense of Sullivan.