bluuebunny/crossref_metadata_2025 huggingface dataset:
Fast‐efficient algorithm of high‐profile intra prediction for H.264 encoding system
Authors: Hsia Shih‐Chang , Wong Wing‐Kwong , Shih Yen‐Hung
Published: October 2017

This study presents a fast intra‐prediction algorithm for a high‐profile H.264 encoder. First, a pre‐decision algorithm is proposed to reject the impossible block size based on image variance. Then a fast 4 × 4 block prediction algorithm is proposed to select four possible modes from nine predicted modes based on the edge‐filtering detection. With a hierarchical approach, the 8 × 8 block prediction is based on the result of the chosen 4 × 4 block mode. This approach selects only one to five modes of H.264 coding from nine prediction modes. Following the prediction of the 16 × 16 luminance block and 8 × 8 chrominance block is mapped by the result of the 8 × 8 luminance block by checking only one to two modes. The pre‐decision algorithm, the fast 4 × 4, 8 × 8 and 16 × 16 block prediction algorithms can be combined to improve the coding speed. Simulations demonstrate that the proposed algorithm can save about 70% coding time at most for intra‐frame coding in the H.264 system while increasing only about 1% bit‐rate with a negligible peak signal‐to‐noise ratio drop.
SOLAR-ISS: A new reference spectrum based on SOLAR/SOLSPEC observations
Authors: Meftah M. , Damé L. , Bolsée D. , Hauchecorne A. , Pereira N. , Sluse D. , Cessateur G. , Irbah A. , Bureau J. , Weber M. , Bramstedt K. , Hilbig T. , Thiéblemont R. , Marchand M. , Lefèvre F. , Sarkissian A. , Bekki S.
Published: October 2017

Context. Since April 5, 2008 and up to February 15, 2017, the SOLar SPECtrometer (SOLSPEC) instrument of the SOLAR payload on board the International Space Station (ISS) has performed accurate measurements of solar spectral irradiance (SSI) from the middle ultraviolet to the infrared (165 to 3088 nm). These measurements are of primary importance for a better understanding of solar physics and the impact of solar variability on climate. In particular, a new reference solar spectrum (SOLAR-ISS) is established in April 2008 during the solar minima of cycles 23–24 thanks to revised engineering corrections, improved calibrations, and advanced procedures to account for thermal and aging corrections of the SOLAR/SOLSPEC instrument.

Aims. The main objective of this article is to present a new high-resolution solar spectrum with a mean absolute uncertainty of 1.26% at 1σ from 165 to 3000 nm. This solar spectrum is based on solar observations of the SOLAR/SOLSPEC space-based instrument.

Methods. The SOLAR/SOLSPEC instrument consists of three separate double monochromators that use concave holographic gratings to cover the middle ultraviolet (UV), visible (VIS), and infrared (IR) domains. Our best ultraviolet, visible, and infrared spectra are merged into a single absolute solar spectrum covering the 165–3000 nm domain. The resulting solar spectrum has a spectral resolution varying between 0.6 and 9.5 nm in the 165–3000 nm wavelength range. We build a new solar reference spectrum (SOLAR-ISS) by constraining existing high-resolution spectra to SOLAR/SOLSPEC observed spectrum. For that purpose, we account for the difference of resolution between the two spectra using the SOLAR/SOLSPEC instrumental slit functions.

Results. Using SOLAR/SOLSPEC data, a new solar spectrum covering the 165–3000 nm wavelength range is built and is representative of the 2008 solar minimum. It has a resolution better than 0.1 nm below 1000 nm and 1 nm in the 1000–3000 nm wavelength range. The new solar spectrum (SOLAR-ISS) highlights significant differences with previous solar reference spectra and with solar spectra based on models. The integral of the SOLAR-ISS solar spectrum yields a total solar irradiance of 1372.3 ± 16.9 Wm−2 at 1σ, that is yet 11 Wm−2 over the value recommended by the International Astronomical Union in 2015.
Diffusive transport of energetic electrons in the solar corona: X-ray and radio diagnostics
Authors: Musset S. , Kontar E. P. , Vilmer N.
Published: October 2017

Context. Imaging spectroscopy in X-rays with RHESSI provides the possibility to investigate the spatial evolution of X-ray emitting electron distribution and therefore, to study transport effects on energetic electrons during solar flares.

Aims. We study the energy dependence of the scattering mean free path of energetic electrons in the solar corona.

Methods. We used imaging spectroscopy with RHESSI to study the evolution of energetic electrons distribution in various parts of the magnetic loop during the 2004 May 21 flare. We compared these observations with the radio observations of the gyrosynchrotron radiation of the same flare and with the predictions of a diffusive transport model.

Results. X-ray analysis shows a trapping of energetic electrons in the corona and a spectral hardening of the energetic electron distribution between the top of the loop and the footpoints. Coronal trapping of electrons is stronger for radio-emitting electrons than for X-ray-emitting electrons. These observations can be explained by a diffusive transport model.

Conclusions. We show that the combination of X-ray and radio diagnostics is a powerful tool to study electron transport in the solar corona in different energy domains. We show that the diffusive transport model can explain our observations, and in the range 25–500 keV, the scattering mean free path of electrons decreases with electron energy. We can estimate for the first time the scattering mean free path dependence on energy in the corona.
Palladium-Catalyzed Copper-Promoted Hiyama-Type Carbon–­Carbon Cross-Coupling Reactions of Dihetaryl Disulfides as ­Electrophiles
Authors: Quan Zheng-Jun , Wang Xi-Cun , Liu Ming-Xia , Gong Hai-Peng
Published: October 2017

Dihetaryl disulfides were used as electrophiles in a palladium-catalyzed carbon–carbon cross-coupling reaction with arylsilanes to ­realize a Hiyama-type reaction. This unique transformation shows high reactivity, excellent functional-group tolerance, and mild reaction conditions, making it an attractive alternative to conventional cross-coupling approaches for carbon−carbon bond construction.
Activation of a Carbon–Carbon Bond in Internal Alkynes: Vinylidene Rearrangement of Disubstituted Alkynes at an Ir Complex
Authors: Ishii Youichi , Kuwabara Takuya , Takamori Shuhei , Kishi Satoshi , Watanabe Takahiro , Ikeda Yousuke , Kodama Shintaro , Minami Yasunori , Hiyama Tamejiro
Published: October 2017

Reactions of [Cp*Ir(PPh3)Cl2] with various internal acyl­alkynes in the presence of NaBArF
4 resulted in the selective formation of iridacycles via vinylidene rearrangement. 13C-labeling experiments revealed that the acyl group selectively migrates to the other acetylenic carbon atom. This trend is the same as that in the vinylidene rearrangement of internal alkynes at a group 8 metal center.
Treatment of Ulnar Impaction Syndrome with and without Central TFC Lesion
Authors: Herold Alexandra , Unglaub Frank , Megerle Kai , Erne Holger , Löw Steffen
Published: October 2017

Background Arthroscopic debridement of the triangular fibrocartilage (TFC) is well accepted in patients with ulnar impaction syndrome with central TFC lesions. Treatment remains controversial, however, when there is no such lesion from radiocarpal view.

Purpose This study assessed the clinical outcome of arthroscopic central TFC resection and debridement and secondary ulnar shortening in patients with ulnar impaction with central TFC lesion compared with patients without TFC lesion.

Patients and Methods Thirty-two consecutive patients with ulnar impaction syndrome were arthroscopically treated, 16 of whom had a central lesion of the TFC that was debrided. In the 16 patients with no lesion from the radiocarpal view, the TFC was centrally resected and debrided to decompress the ulnocarpal joint. Persisting symptoms necessitated ulnar shortening in four patients in each group. Two patients underwent repeat arthroscopic TFC debridement. All patients were examined at 3, 6, and 12 months, and at final follow-up (mean: 1.7 years) following arthroscopy, respectively ulnar shortening or hardware removal.

Results In both groups, pain, Krimmer, and DASH scores significantly improved. Improvements of DASH scores were significantly higher in patients without lesion at 12 months and at final follow-up. For other parameters, no significant difference was found between the two groups.

Conclusion In both situations, with and without central TFC lesion, resection and debridement sufficiently reduced the ulnar-sided wrist pain and improved function in three out of four patients, and therefore qualified as the first-line treatment of ulnar impaction syndrome as arthroscopy is performed, anyway. Those patients who complained of persisting or recurrent ulnar-sided wrist pain finally benefitted from ulnar shortening osteotomy as the secondary procedure.

Level of Evidence Therapeutic III, case–control study.
Herausforderungen der magnetresonanztomografischen Diagnose der axialen Spondylarthritis
Authors: Bach A. , Hermann K.-G.
Published: October 2017

In der Bildgebung der axialen Spondylarthritiden einschliesslich der ankylosierenden Spondylitis steht das konventionelle Röntgenbild der Sakroiliakalgelenke (SIG) an erster Stelle. Da sich pathologische Veränderungen hier jedoch erst spät nachweisen lassen, verzögert sich die Diagnosestellung im Schnitt um 5–9 Jahre. Die fehlende Sensitivität des Röntgenbildes für frühe Krankheitsstadien lässt also eine diagnostische Lücke entstehen, welche auch den Therapiebeginn erheblich verzögern kann. Mit der Magnetresonanztomografie (MRT) der SIG steht uns eine moderne, sehr sensitive Modalität zur Erkennung der frühen Spondylarthritis (SpA) zur Verfügung, welche diese Lücke schließen kann. Die heute flächendeckende Verfügbarkeit geeigneter MRT-Geräte und die immer genauere Klassifikation der SIG-Veränderungen machen sie zu einer Untersuchungsmethode, welche nicht mehr den großen Krankenhäusern vorbehalten ist, sondern überall im klinischen Alltag eingesetzt werden kann und sollte. Essenziell für die Bildinterpretation ist die Kenntnis der in der MRT sichtbaren Pathologien, welche in aktive und strukturelle Veränderungen eingeteilt werden. Zu den aktiven Veränderungen zählen paraartikuläre Osteitiden, Synovitiden, Kapsulitiden und Enthesitiden; zu den chronischen Veränderungen Erosionen, subchondrale Sklerosierungen, transartikuläre Knochenbrücken und periartikuläre Verfettungen. Sie lassen sich durch ihr jeweils typisches Signalverhalten und ihre Lage gut charakterisieren. Zusätzlich ist das Wissen über mögliche anatomischen Varianten und Differenzialdiagnosen relevant – in unklaren Fällen kann eine ergänzende computertomoprafische Bildgebung hilfreich sein. Die aktuelle Diskussion neuer Konzepte (wie bspw. das „Backfill“ in den SIG) zeigt, dass die diagnostischen Möglichkeiten auch hier in Zukunft noch vielfältiger werden. Eine interdisziplinäre Zusammenarbeit von Rheumatologen und Radiologen mit optimaler Ausschöpfung dieser „frühen“ diagnostischen und therapeutischen Möglichkeiten trägt zu einer Verbesserung der Patientenversorgung bei.
Cesarean Delivery in a Case of Persistent Second Trimester Ovarian Hyperstimulation Syndrome
Authors: Torky Haitham
Published: October 2017

Background Ovarian hyperstimulation syndrome develops as an iatrogenic complication related to ovulation induction. It is usually self-limiting with complete resolution expected within 10–14 days.

Case The current case is a report of an unusually prolonged course of ovarian hyperstimulation syndrome persisting until 22 weeks of gestation, accidentally discovered and managed by cesarean section due to an obstetric indication.

Conclusion Clinicians should be aware of this possibility when managing cases of IVF pregnancy.
Verhindert eine höhere Raumtemperatur im Erstversorgungsraum die Auskühlung von Frühgeborenen unter 1500 g?
Authors: Johannsen Janaina , Vochem Matthias , Neuberger Patrick
Published: October 2017

Ziel Die Prävention der Hypothermie ist eine der wichtigsten Maßnahmen bei der Erstversorgung kleiner Frühgeborener. Es existiert eine umfassende Datenlage zu diversen Präventionsmaßnahmen (z. B. Anwärmen der Atemluft, sterile Folien, Wärmestrahler, Gelmatratzen etc.), jedoch gibt es bislang keine Empfehlungen bzw. Vergleichsstudien zu dem Teilaspekt der optimalen Raumtemperatur im Erstversorgungsraum.

Methoden Vergleich der rektalen Aufnahmetemperaturen von Frühgeborenen unter 1500 g nach postnataler Versorgung in zwei unterschiedlich warmen Erstversorgungsräumen (28°C vs. 34°C) als retrospektive Kohortenstudie.

Ergebnisse Es zeigte sich, dass eine höhere Temperatur im Erstversorgungsraum signifikant weniger hypotherme Frühgeborene (Aufnahmetemperatur <36,5°C), jedoch auch mehr Frühgeborene mit Körpertemperatur >37,5°C zur Folge hatte.

Fazit Die Auskühlung von Frühgeborenen könnte durch eine höhere Temperatur im Erstversorgungsraum mit verhindert werden. Weitere Studien sollten diesen Teilaspekt untermauern, wodurch eventuell eine Aussage zur optimalen Temperatur im Erstversorgungsraum gegeben werden könnte.
Nuklearmedizin in Diagnostik und Therapie rheumatischer Erkrankungen: Skelettszintigrafie, Hybridbildgebung mit SPECT/CT und PET/CT sowie Radiosynoviorthese
Authors: Hautzel Hubertus , Schneider Matthias , Richter Jutta
Published: October 2017

Ziel der modernen nuklearmedizinischen Diagnostik sind neben der im Fokus stehenden Früherkennung der Erkrankungen auch die Kontrolle und das Monitoring der Therapie und damit des Krankheitsverlaufes. Die Hybridmethoden nehmen inzwischen einen hohen Stellenwert in der Forschung ein, in der klinischen Routine und v. a. im Follow-up sollten ihre Indikation und Anwendung neben Kosten/Nutzenabwägungen unter Strahlenexpositionsgründen kritisch geprüft werden. Die Arbeit gibt einen Überblick über die aktuell in Diagnostik und Therapie eingesetzten Verfahren.
Influence of Paclitaxel and Heparin on Vitality, Proliferation and Cytokine Production of Endometrial Cancer Cells
Authors: Dinkic Christine , Kruse Anja , Zygmunt Marek , Schuetz Florian , Brucker Janina , Rom Joachim , Sohn Christof , Fluhr Herbert
Published: October 2017

Background Cancer patients have a higher risk for thromboembolic events compared to healthy individuals and are often treated with heparins. A beneficial effect of heparins on tumor patients above and beyond the classic anticoagulation effect has been reported, leading to an increased focus on the use of heparins in anticancer treatment. In recent years, it has become apparent that microenvironments greatly affect tumor development and can be a major source of tumor-promoting factors. Cytokines play an important role in tumor microenvironments, inducing carcinogenesis and influencing tumor progression by promoting angiogenesis, metastatic potential and immunosuppression. The possible interaction of heparins and cytokines could also have an effect on cancer cells.

Methods This study investigated the effect of paclitaxel (PTX) combined with heparins on the vitality of endometrial cancer cells using viability and cytotoxicity assays. The study also examined whether treatment with paclitaxel and heparin influences cytokine secretion or expression.

Results Heparin treatment did not influence cell viability, and no influence of heparins in combination with paclitaxel was seen for the evaluated cancer cell lines HEC-1-A, KLE, RL 95-2 and AN3-CA compared to untreated cells. Secretion of the cytokines CCL5, CCL2 and IL-6 increased after paclitaxel treatment in several endometrial cancer cell lines, but no general effect on cytokine secretion was detected after heparin treatment. A significant decrease in CCL5 expression was only detected in KLE cells following treatment with heparin and paclitaxel, and an increase in the expression of CCL5 in RL 95-2 cells.

Conclusion Further in-depth studies are needed to investigate the functions of cytokines CCL2, CCL5 and IL-6 in endometrial cancer cells treated with paclitaxel. Although no general effect on cytokine secretion was detected following heparin treatment, a selective modulatory impact could exist.
Assessing the Clinical Benefit of Systemic Adjuvant Therapies for Early Breast Cancer
Authors: Möbus Volker , Hell Susanne , Schmidt Marcus
Published: October 2017

Oncologic therapy is currently undergoing significant changes. A number of innovative targeted medications currently in clinical development have raised high expectations. With that in mind, discussions about terms such as “clinical benefit” and “clinical relevance” are highly topical. This also applies to further developments in the field of adjuvant systemic therapies for early-stage breast cancer. As the treatment aim is curative, assessment of the clinical benefit of adjuvant therapies must be largely based on efficacy outcomes. The focus must be on improving disease-free survival rates and lowering the risk of recurrence. Because of the current low mortality rates, statements about overall survival rates are only possible after very long observation periods. Consequently, new drugs in adjuvant therapies should be considered as offering a clinical benefit, if they reduce the risk of recurrence below current low levels of risk. The evidence for established adjuvant therapy standards in early-stage breast cancer can be used as objective criteria for comparison. This review article considers the requirements for clinical benefit of new adjuvant therapies for early breast cancer, based on examples from adjuvant endocrine therapy, adjuvant polychemotherapy and adjuvant anti-HER2 therapy.
Coupling of SWITG and SWTEM in the presence of impurities in tokamak plasmas
Authors: Zhong Siyao , Huang Qianhong , Gong X. Y. , Zhang Neng , Dong J. Q. , Su JiaHao
Published: October 2017

The coupling of the short wavelength ion temperature gradient mode (SWITG) and trapped electron mode (SWTEM) in the presence of impurity ions is numerically studied in tokamak plasmas. It is found that the coupling of SWITG and SWTEM modes is divided into hybrid and coexistent cases. The impurity ions always have stabilizing effects on the hybrid mode (namely, SWTE-ITG) with small ηi (ηi < 0.5), which is different from the conventional TE-ITG mode. In the lager ηi (ηi > 0.5) regime, the impurity ions with the density profiles peaked inwardly (outwardly) stabilize (destabilize) the SWTE-ITG mode. Another new finding in this paper is that the impurity ions stabilize the SWTEM mode independent of whether their density profile is peaked inwardly or outwardly. The result for the SWITG mode is similar to the SWTE-ITG mode in the lager ηi regime, except that the excitation of the SWTEM mode requires ηi higher than a certain threshold. In addition, the kθρs spectra, eigenmode structures, and the effects of different impurity ion species on the modes are discussed.
High-temperature crystallized thin-film PZT on thin polyimide substrates
Authors: Liu Tianning , Wallace Margeaux , Trolier-McKinstry Susan , Jackson Thomas N.
Published: October 2017

Flexible piezoelectric thin films on polymeric substrates provide advantages in sensing, actuating, and energy harvesting applications. However, direct deposition of many inorganic piezoelectric materials such as Pb(Zrx,Ti1-x)O3 (PZT) on polymers is challenging due to the high temperature required for crystallization. This paper describes a transfer process for PZT thin films. The PZT films are first grown on a high-temperature capable substrate such as platinum-coated silicon. After crystallization, a polymeric layer is added, and the polymer-PZT combination is removed from the high-temperature substrate by etching away a release layer, with the polymer layer then becoming the substrate. The released PZT on polyimide exhibits enhanced dielectric response due to reduction in substrate clamping after removal from the rigid substrate. For Pb(Zr0.52,Ti0.48)0.98Nb0.02O3 films, release from Si increased the remanent polarization from 17.5 μC/cm2 to 26 μC/cm2. In addition, poling led to increased ferroelastic/ferroelectric realignment in the released films. At 1 kHz, the average permittivity was measured to be around 1160 after release from Si with a loss tangent below 3%. Rayleigh measurements further confirmed the correlation between diminished substrate constraint and increased domain wall mobility in the released PZT films on polymers.
Self-biased magnetoelectric charge coupling in transducer of SmFe2, Pb(Zr,Ti)O3 stack, and stepped horn substrate with multi-frequency effect
Authors: Tang Chengpei , Lu Caijiang , Gao Hongli , Fu Guoqiang
Published: October 2017

This paper presents a broadband, self-biased magnetoelectric (ME) charge coupling in a transducer comprising of a negative magnetostrictive SmFe2 plate, a piezoelectric Pb(Zr,Ti)O3 (PZT) stack, and a stepped horn substrate. By using the SmFe2 plate with a large anisotropic field, an outstanding self-biased piezomagnetic effect is realized. The horn serves as a waveguide with multiple resonances and converges vibrating energy excited by the SmFe2 plate from the wide side to the narrow side, which results in a higher vibrating magnification at the position of the PZT-stack. Then, a strong mechanical-electric coupling is realized by the use of the PZT-stack with high capacitance. Consequently, several large peaks of ME charge response with magnitudes of 1.02–18.99 nC/Oe in the 0.1–50 kHz range are observed at zero-biased magnetic field. This demonstrates that the proposed broadband self-biased structure may be useful for multifunctional devices such as low frequency AC magnetic field sensors or multi-frequency energy harvesters.
A characterization of the inertial range in forced-damped Hasegawa-Mima turbulence
Authors: Tran Thanh Tinh , Jhang Hogun , Kim Juhyung , Kim S. S.
Published: October 2017

From the nonlinear simulations of the two-dimensional forced-damped Hasegawa–Mima equation, we show that a Reynolds number-like parameter, Rew, can represent a power law exponent of the energy spectrum in Hasegawa–Mima turbulence. Rew is defined as the ratio of nonlinear convection to dissipation. For a same value of Rew, the power law exponent in the inertial range is shown to be uniquely determined regardless of the forcing and dissipation conditions. At high Rew, the power law exponent asymptotically converges to −7.2, consistent with a recent theoretical prediction based on the shell model [Gürcan et al., Plasma Phys. Controlled Fusion 52, 045002 (2010)].
Orientational order and dynamics of interfacial water near a hexagonal boron-nitride sheet: An ab initio molecular dynamics study
Authors: Kayal Abhijit , Chandra Amalendu
Published: October 2017

Structural and dynamical properties of interfacial water molecules near a hexagonal boron nitride sheet (h-BN) are investigated by means of Born-Oppenheimer molecular dynamics simulations. Orientational profiles in the interfacial regions reveal two distinct types of water molecules near the BN surface. Depending on the positions of the water molecules, on top of either N or B atoms, one type contains water molecules that are oriented with one OH bond pointing toward the N atoms and the other type contains water molecules that remain parallel to the BN sheet. Distinct hydrogen bonding and stabilization energies of these two types of water molecules are found from our calculations. In order to see the effects of dispersion interactions, simulations are performed with the BLYP (Becke-Lee-Yang-Parr) functional and also BLYP with Grimme’s D3 corrections (BLYP-D3). An enhancement of water ordering near the surface is observed with the inclusion of dispersion corrections. Further analysis of the diffusion coefficients, rotational time correlation functions, and hydrogen bond dynamics shows that water molecules near the h-BN sheet move faster compared to bulk water molecules both translationally and rotationally. The water molecules in the first layer are found to show substantial lateral diffusion. The escape dynamics of water from the solvation layer at the BN surface is also looked at in the current study. We have also investigated some of the electronic properties of interfacial water such as the charge density and dipole moment. It is found that the water molecules at the surface of the BN sheet have a lower dipole moment than bulk molecules.
Electronic structure of BN-aromatics: Choice of reliable computational tools
Authors: Mazière Audrey , Chrostowska Anna , Darrigan Clovis , Dargelos Alain , Graciaa Alain , Chermette Henry
Published: October 2017

The importance of having reliable calculation tools to interpret and predict the electronic properties of BN-aromatics is directly linked to the growing interest for these very promising new systems in the field of materials science, biomedical research, or energy sustainability. Ionization energy (IE) is one of the most important parameters to approach the electronic structure of molecules. It can be theoretically estimated, but in order to evaluate their persistence and propose the most reliable tools for the evaluation of different electronic properties of existent or only imagined BN-containing compounds, we took as reference experimental values of ionization energies provided by ultra-violet photoelectron spectroscopy (UV-PES) in gas phase—the only technique giving access to the energy levels of filled molecular orbitals. Thus, a set of 21 aromatic molecules containing B–N bonds and B–N–B patterns has been merged for a comparison between experimental IEs obtained by UV-PES and various theoretical approaches for their estimation. Time-Dependent Density Functional Theory (TD-DFT) methods using B3LYP and long-range corrected CAM-B3LYP functionals are used, combined with the ΔSCF approach, and compared with electron propagator theory such as outer valence Green’s function (OVGF, P3) and symmetry adapted cluster-configuration interaction ab initio methods. Direct Kohn-Sham estimation and “corrected” Kohn-Sham estimation are also given. The deviation between experimental and theoretical values is computed for each molecule, and a statistical study is performed over the average and the root mean square for the whole set and sub-sets of molecules. It is shown that (i) ΔSCF+TDDFT(CAM-B3LYP), OVGF, and P3 are the most efficient way for a good agreement with UV-PES values, (ii) a CAM-B3LYP range-separated hybrid functional is significantly better than B3LYP for the purpose, especially for extended conjugated systems, and (iii) the “corrected” Kohn-Sham result is a fast and simple way to predict IEs.
Magnetostrictive and magnetic effects in Fe-27%Co laminations
Authors: Savary Maxime , Hubert Olivier , Helbert Anne-Laure , Baudin Thierry , Waeckerlé Thierry
Published: October 2017

The present paper deals with the characterization of the magnetostriction of the Fe-27%Co alloy. When this alloy is annealed in the ferritic domain (between 700°C and 940°C) and submitted to a slow cooling, it exhibits a low and isotropic magnetostriction over a wide induction range (±1.5T). One reason that can explain this phenomenon is a high temperature selection of magnetic bi-domains preferentially oriented in the rolling plane. As soon as this material is annealed in the austenitic domain or quenched from the ferritic domain, the low and isotropic magnetostriction disappears giving way to a classical quadratic magnetostrictive behavior.
Piezoelectric response and electrical properties of Pb(Zr1-xTix)O3 thin films: The role of imprint and composition
Authors: Cornelius T. W. , Mocuta C. , Escoubas S. , Merabet A. , Texier M. , Lima E. C. , Araujo E. B. , Kholkin A. L. , Thomas O.
Published: October 2017

The compositional dependence of the piezoelectric properties of self-polarized PbZr1-xTixO3 (PZT) thin films deposited on Pt/TiO2/SiO2/Si substrates (x = 0.47, 0.49 and 0.50) was investigated by in situ synchrotron X-ray diffraction and electrical measurements. The latter evidenced an imprint effect in the studied PZT films, which is pronounced for films with the composition of x = 0.50 and tends to disappear for x = 0.47. These findings were confirmed by in situ X-ray diffraction along the crystalline [100] and [110] directions of the films with different compositions revealing asymmetric butterfly loops of the piezoelectric strain as a function of the electric field; the asymmetry is more pronounced for the PZT film with a composition of x = 0.50, thus indicating a higher built-in electric field. The enhancement of the dielectric permittivity and the effective piezoelectric coefficient at compositions around the morphotropic phase boundary were interpreted in terms of the polarization rotation mechanism and the monoclinic phase in the studied PZT thin films.
The characters of ion acoustic rogue waves in nonextensive plasma
Authors: Du Hai-su , Lin Mai-mai , Gong Xue , Duan Wen-shan
Published: October 2017

Several well-known nonlinear waves in the rational solutions of the nonlinear Schrödinger equation are studied in two-component plasmas consisting of ions fluid and nonextensive electrons, such as Kuznetsov–Ma breather (K-M), bright soliton, rogue wave (RW), Akhmediev breather (AB) and dark soliton, and so on. In this paper, we have investigated the characteristics of K-M, AB, and RW's propagation in plasma with nonextensive electron distribution, and the dependence of amplitude and width for ion acoustic rogue waves in this system. It is found that K-M' triplet is appearance-disappearance-appearance-disappearance. AB solitons only appear once and RW is a single wave that appears from nowhere and then disappears. It is also noted that the wave number and nonextensive parameter of electrons have a significant influence on the maximum envelope amplitude, but, the influence of the width was not significant. At the same time, the effects of the small parameter, which represent the nonlinear strength, on the amplitude and width of ion acoustic rogue waves are also being highlighted.
Modeling quantum yield, emittance, and surface roughness effects from metallic photocathodes
Authors: Dimitrov D. A. , Bell G. I. , Smedley J. , Ben-Zvi I. , Feng J. , Karkare S. , Padmore H. A.
Published: October 2017

Detailed measurements of momentum distributions of emitted electrons have allowed the investigation of the thermal limit of the transverse emittance from metal photocathodes. Furthermore, recent developments in material design and growth have resulted in photocathodes that can deliver high quantum efficiency and are sufficiently robust to use in high electric field gradient photoinjectors and free electron lasers. The growth process usually produces photoemissive material layers with rough surface profiles that lead to transverse accelerating fields and possible work function variations, resulting in emittance growth. To better understand the effects of temperature, density of states, and surface roughness on the properties of emitted electrons, we have developed realistic three-dimensional models for photocathode materials with grated surface structures. They include general modeling of electron excitation due to photon absorption, charge transport, and emission from flat and rough metallic surfaces. The models also include image charge and field enhancement effects. We report results from simulations with flat and rough surfaces to investigate how electron scattering, controlled roughness, work function variation, and field enhancement affect emission properties. Comparison of simulation results with measurements of the quantum yield and transverse emittance from flat Sb emission surfaces shows the importance of including efficient modeling of photon absorption, temperature effects, and the material density of states to achieve agreement with the experimental data.
GaSb/AlAsSb resonant tunneling diodes with GaAsSb emitter prewells
Authors: Pfenning Andreas , Knebl Georg , Hartmann Fabian , Weih Robert , Meyer Manuel , Bader Andreas , Emmerling Monika , Worschech Lukas , Höfling Sven
Published: October 2017

We investigate the electronic transport properties of GaSb/AlAsSb double barrier resonant tunneling diodes with pseudomorphically grown ternary GaAsxSb1-x emitter prewells over a broad temperature range. At room temperature, resonant tunneling is observed and the peak-to-valley current ratio (PVCR) is enhanced with the increasing As mole fraction from 1.88 (GaAs0.07Sb0.93 prewell), to 2.08 (GaAs0.09Sb0.91 prewell) up to 2.36 (GaAs0.11Sb0.89 prewell). The rise in PVCR is attributed to an enhanced carrier density at the Γ-valley within the emitter prewell. On the contrary at cryogenic temperatures, increasing the As mole fractions reduces the PVCR. At a temperature of T=4.2 K, reference samples without incorporation of an emitter prewell containing As show PVCRs up to 20.4. We attribute the reduced PVCR to a degraded crystal quality of the resonant tunneling structure caused by As incorporation and subsequently an enhanced defect scattering at the interfaces.
An effective toy model in Mn(C) for selective measurements in quantum mechanics
Authors: Vecsernyés Péter
Published: October 2017

The non-selective and selective measurements of a self-adjoint observable A in quantum mechanics are interpreted as “jumps” of the state of the measured system into a decohered or pure state, respectively, characterized by the spectral projections of A. However, one may try to describe the measurement results as asymptotic states of a dynamical process, where the non-unitarity of time evolution arises as an effective description of the interaction of the measured system with the measuring device. The dynamics we present is a two-step dynamics: the first step is the non-selective measurement or decoherence, which is known to be described by the linear, deterministic Lindblad equation. The second step is a process from the resulted decohered state to a pure state, which is described by an effective non-linear “randomly chosen” toy model dynamics: the pure states arise as asymptotic fixed points, and their emergent probabilities are the relative volumes of their attractor regions.
Temperature and frequency dependence of the coercive field of 0.71PbMb1/3Nb2/3O3–0.29PbTiO3 relaxor-based ferroelectric single crystal
Authors: Zhang Yang , Chen Zhaojiang , Cao Wenwu , Zhang Zhongwu
Published: October 2017

The hysteresis loop of ferroelectric materials becomes narrower with the increase in temperature due to energy barrier reduction, while the coercive field level increases with frequency due to the inertia of polarization reversal. These two competing effects determine the limiting operation field of medical imaging transducers at high frequencies. We have measured the coercive field of the 0.71PbMb1/3Nb2/3O3–0.29PbTiO3 single crystal as functions of both temperature and frequency. It was found that the coercive field linearly decreases with temperature at all frequencies. Related theoretical analysis was also performed to understand the physics behind the observed phenomena.
Excited states using semistochastic heat-bath configuration interaction
Authors: Holmes Adam A. , Umrigar C. J. , Sharma Sandeep
Published: October 2017

We extend our recently developed heat-bath configuration interaction (HCI) algorithm, and our semistochastic algorithm for performing multireference perturbation theory, to calculate excited-state wavefunctions and energies. We employ time-reversal symmetry, which reduces the memory requirements by more than a factor of two. An extrapolation technique is introduced to reliably extrapolate HCI energies to the full CI limit. The resulting algorithm is used to compute fourteen low-lying potential energy surfaces of the carbon dimer using the cc-pV5Z basis set, with an estimated error in energy of 30-50 μHa compared to full CI. The excitation energies obtained using our algorithm have a mean absolute deviation of 0.02 eV compared to experimental values.
A statistical model of false negative and false positive detection of phase singularities
Authors: Jacquemet Vincent
Published: October 2017

The complexity of cardiac fibrillation dynamics can be assessed by analyzing the distribution of phase singularities (PSs) observed using mapping systems. Interelectrode distance, however, limits the accuracy of PS detection. To investigate in a theoretical framework the PS false negative and false positive rates in relation to the characteristics of the mapping system and fibrillation dynamics, we propose a statistical model of phase maps with controllable number and locations of PSs. In this model, phase maps are generated from randomly distributed PSs with physiologically-plausible directions of rotation. Noise and distortion of the phase are added. PSs are detected using topological charge contour integrals on regular grids of varying resolutions. Over 100 × 106 realizations of the random field process are used to estimate average false negative and false positive rates using a Monte-Carlo approach. The false detection rates are shown to depend on the average distance between neighboring PSs expressed in units of interelectrode distance, following approximately a power law with exponents in the range of 1.14 to 2 for false negatives and around 2.8 for false positives. In the presence of noise or distortion of phase, false detection rates at high resolution tend to a non-zero noise-dependent lower bound. This model provides an easy-to-implement tool for benchmarking PS detection algorithms over a broad range of configurations with multiple PSs.
On static triplet structures in fluids with quantum behavior
Authors: Sesé Luis M.
Published: October 2017

The problem of the equilibrium triplet structures in fluids with quantum behavior is discussed. Theoretical questions of interest to the real space structures are addressed by studying the three types of structures that can be determined via path integrals (instantaneous, centroid, and total thermalized-continuous linear response). The cases of liquid para-H2 and liquid neon on their crystallization lines are examined with path-integral Monte Carlo simulations, the focus being on the instantaneous and the centroid triplet functions (equilateral and isosceles configurations). To analyze the results further, two standard closures, Kirkwood superposition and Jackson-Feenberg convolution, are utilized. In addition, some pilot calculations with path integrals and closures of the instantaneous triplet structure factor of liquid para-H2 are also carried out for the equilateral components. Triplet structural regularities connected to the pair radial structures are identified, a remarkable usefulness of the closures employed is observed (e.g., triplet spatial functions for medium-long distances, triplet structure factors for medium k wave numbers), and physical insight into the role of pair correlations near quantum crystallization is gained.
Epitaxial growth of GaSb on V-grooved Si (001) substrates with an ultrathin GaAs stress relaxing layer
Authors: Li Qiang , Lai Billy , Lau Kei May
Published: October 2017

We report epitaxial growth of GaSb nano-ridge structures and planar thin films on V-groove patterned Si (001) substrates by leveraging the aspect ratio trapping technique. GaSb was deposited on {111} Si facets of the V-shaped trenches using metal-organic chemical vapor deposition with a 7 nm GaAs growth initiation layer. Transmission electron microscopy analysis reveals the critical role of the GaAs layer in providing a U-shaped surface for subsequent GaSb epitaxy. A network of misfit dislocations was uncovered at the GaSb/GaAs hetero-interface. We studied the evolution of the lattice relaxation as the growth progresses from closely pitched GaSb ridges to coalesced thin films using x-ray diffraction. The omega rocking curve full-width-at-half-maximum of the resultant GaSb thin film is among the lowest values reported by molecular beam epitaxy, substantiating the effectiveness of the defect necking mechanism. These results thus present promising opportunities for the heterogeneous integration of devices based on 6.1 Å family compound semiconductors.
Exploiting bistable oscillator subharmonics for magnified broadband vibration energy harvesting
Authors: Huguet Thomas , Badel Adrien , Lallart Mickaël
Published: October 2017

Recent research on primary battery alternatives for supplying autonomous wireless devices has recently highlighted the advantages of nonlinear oscillators' dynamics and more particularly bistable oscillators' behavior for ambient vibration harvesting. The key property of bistable oscillators compared to linear ones is their enhanced operational frequency bandwidth under harmonic excitation, potentially leading to a better adaptation to the environment. However, the classical frequency response characterization of such devices does not reveal all the possible dynamic behaviors offered by bistable oscillators. Thus, subharmonic motions are experimentally investigated in this letter, and their energy harvesting potential as well as their ability to enhance the bistable generator bandwidth is evaluated. The results obtained with a generator integrating buckled beams for the bistability feature show that, in addition to the commonly considered harmonic behavior, subharmonics allow widening of the useful operating frequency band of the bistable microgenerator by 180% compared to the sole exploitation of the first harmonic motion.
Capillary assisted deposition of carbon nanotube film for strain sensing
Authors: Li Zida , Xue Xufeng , Lin Feng , Wang Yize , Ward Kevin , Fu Jianping
Published: October 2017

Advances in stretchable electronics offer the possibility of developing skin-like motion sensors. Carbon nanotubes (CNTs), owing to their superior electrical properties, have great potential for applications in such sensors. In this paper, we report a method for deposition and patterning of CNTs on soft, elastic polydimethylsiloxane (PDMS) substrates using capillary action. Micropillar arrays were generated on PDMS surfaces before treatment with plasma to render them hydrophilic. Capillary force enabled by the micropillar array spreads CNT solution evenly on PDMS surfaces. Solvent evaporation leaves a uniform deposition and patterning of CNTs on PDMS surfaces. We studied the effect of the CNT concentration and micropillar gap size on CNT coating uniformity, film conductivity, and piezoresistivity. Leveraging the piezoresistivity of deposited CNT films, we further designed and characterized a device for the contraction force measurement. Our capillary assisted deposition method of CNT films showed great application potential in fabrication of flexible CNT thin films for strain sensing.
Is repulsion good for the health of chimeras?
Authors: Jalan Sarika , Ghosh Saptarshi , Patra Bibhabasu
Published: October 2017

Yes! Very much so. A chimera state refers to the coexistence of a coherent-incoherent dynamical evolution of identically coupled oscillators. We investigate the impact of multiplexing of a layer having repulsively coupled oscillators on the occurrence of chimeras in the layer having attractively coupled identical oscillators. We report that there exists an enhancement in the appearance of the chimera state in one layer of the multiplex network in the presence of repulsive coupling in the other layer. Furthermore, we show that a small amount of inhibition or repulsive coupling in one layer is sufficient to yield the chimera state in another layer by destroying its synchronized behavior. These results can be used to obtain insight into dynamical behaviors of those systems where both attractive and repulsive couplings exist among their constituents.
Time-delayed feedback control of coherence resonance chimeras
Authors: Zakharova Anna , Semenova Nadezhda , Anishchenko Vadim , Schöll Eckehard
Published: October 2017

Using the model of a FitzHugh-Nagumo system in the excitable regime, we investigate the influence of time-delayed feedback on noise-induced chimera states in a network with nonlocal coupling, i.e., coherence resonance chimeras. It is shown that time-delayed feedback allows for the control of the range of parameter values where these chimera states occur. Moreover, for the feedback delay close to the intrinsic period of the system, we find a novel regime which we call period-two coherence resonance chimera.
A thorough numerical model of cathode spots challenges conventional wisdom
Authors: Kim Mark H.
Published: October 2017

A new model of cathode spots in vacuum arcs shows that interactions of vacuum arc plasma with the cathode surface do not necessarily lead to explosions.
Thermochromic VO2 thin films on ITO-coated glass substrates for broadband high absorption at infra-red frequencies
Authors: Rajeswaran Bharathi , Pradhan Jitendra K. , Anantha Ramakrishna S. , Umarji Arun M.
Published: October 2017

Thin films of vanadium dioxide (VO2) are deposited on indium tin oxide (ITO), stainless steel (SS), and glass substrates using chemical vapour deposition. X-ray diffraction and Raman spectroscopy measurements confirmed the single phase nature of the VO2, which showed a phase transition from a low conducting state at low temperature(<68 °C) to a high conducting state at high temperature (>68 °C). This was confirmed by electrical conductance and infra-red reflectance measurements. X-ray photoelectron spectroscopy was used to measure the charge states of vanadium species. The optical constants of VO2 were determined using visible and near-infra red(NIR) reflectivity and show that the VO2 film on ITO has a lowered plasma frequency compared with VO2 on glass substrates. The thin films of VO2 enable a broadband of ultra-high absorption at mid-wave infra-red frequencies due to a Fabry-Pérot (F-P) like resonance due to the dielectric properties of ITO, SS, or glass. The tunability of this absorption band via VO2 thickness and the switchability by temperature makes the system attractive for absorptive coatings with controllable emissivity.
On the refinement of the rotation rate based Smagorinsky model using velocity field gradients
Authors: Ghorbaniasl Ghader , Ricks Nathan , Siozos-Rousoulis Leonidas , Degrez Gérard , Contino Francesco
Published: October 2017

In this paper, a gradient-based refinement of the rotation rate-based Smagorinsky (RoSM) subgrid scale (SGS) model is presented. The refined model satisfies the Galilean invariance condition generally, without any assumptions. The suggested model retains the advantages offered by the original RoSM, thus being simple and efficient. It provides a Smagorinsky model constant that is always positive, with low fluctuations in space and time, without the need for any numerical stability control algorithms. The validity of the proposed SGS model is shown through three test cases, namely, a turbulent channel flow, subcritical flow past a stationary cylinder, and a spatially developing free round jet. The refined RoSM provides comparable results with the dynamic Smagorinsky, while matching well to reference data. The refined RoSM is shown to be computationally efficient, being 20% faster than the dynamic Smagorinsky model.