bluuebunny/crossref_metadata_2025 huggingface dataset:
The challenge of safe driving among elderly drivers
Authors: Albert Gila , Lotan Tsippy , Weiss Penina , Shiftan Yoram
Published: August 2017

The challenge of ageing has two key aspects with regard to driving: mobility and safety. It is necessary for elderly adults to preserve independent mobility and activity; however, physical frailty and cognitive limitations have negative effects on their safety. Therefore, the issue of driving, and more specifically, the fostering of safe driving of old people, is crucial, especially due the increasing number of elderly people holding a driving license. The purpose of this Letter is to point out the complexity of elderly driving and to suggest countermeasures by acknowledging that obtaining the correct balance between safety and mobility of older drivers is a complicated and sensitive task. To address this issue, the authors suggest accommodating their driving behaviour and patterns, in light of the deteriorating driving skills, by integrating social and policy procedures and use of emerging technologies. Policy steps to support elderly drivers and their loved ones by gradually controlling driving of elderly population when this becomes risky to them may serve as a desired countermeasure according to a proved tool such as technology. Utilisation of advanced technologies can help to monitor travel and driver behaviour and ability to make the necessary alterations, based on elderly driving skills.
Multimodal connectivity based eloquence score computation and visualisation for computer‐aided neurosurgical path planning
Authors: Bakhshmand Saeed M. , Eagleson Roy , de Ribaupierre Sandrine
Published: August 2017

Non‐invasive assessment of cognitive importance has been a major challenge for planning of neurosurgical procedures. In the past decade, in vivo brain imaging modalities have been considered for estimating the ‘eloquence’ of brain areas. In order to estimate the impact of damage caused by an access path towards a target region inside of the skull, multi‐modal metrics are introduced in this paper. Accordingly, this estimated damage is obtained by combining multi‐modal metrics. In other words, this damage is an aggregate of intervened grey matter volume and axonal fibre numbers, weighted by their importance within the assigned anatomical and functional networks. To validate these metrics, an exhaustive search algorithm is implemented for characterising the solution space and visually representing connectional cost associated with a path initiated from underlying points. In this presentation, brain networks are built from resting state functional magnetic resonance imaging (fMRI) and deterministic tractography. their results demonstrate that the proposed approach is capable of refining traditional heuristics, such as choosing the minimal distance from the lesion, by supplementing connectional importance of the resected tissue. This provides complementary information to help the surgeon in avoiding important functional hubs and their anatomical linkages; which are derived from neuroimaging modalities and incorporated to the related anatomical landmarks.
Distributed fault estimation observer design for multi‐agent systems with switching topologies
Authors: Zhang Ke , Jiang Bin , Cocquempot Vincent
Published: August 2017

A distributed fault estimation observer (DFEO) design is studied for multi‐agent systems with switching topologies. Firstly, a local fault estimation observer is presented for each agent system based on the relative output estimation error. Then by introducing global variables, a global fault estimation observer is proposed by utilising the average dwell‐time technique. Furthermore, a dissipativity‐based distributed observer is presented to handle external disturbances. Finally, simulation results are presented to illustrate the feasibility and effectiveness of the proposed DFEO strategy.
MHz zero‐voltage‐switched isolated resonant converter for wide‐output‐voltage application
Authors: Gu Ling , Jin Ke
Published: August 2017

This study proposes a MHz isolated resonant converter, which achieves buck–boost DC/DC conversion, zero‐voltage switching and the resonant components absorb the parasitic parameters. The DC analysis method and MATLAB computational algorithm are proposed for acquiring the specific circuit characteristics, including the voltage conversion ratio, the rms value of switch current and peak voltage of the semiconductors. The active power and apparent power are also analysed to provide design basis of optimising efficiency. The proposed converter shows greater advantages on voltage stress, current stress and efficiency over traditional isolated Sepic multi‐resonant converter. A wide‐output‐voltage prototype based on the proposed converter was built in the lab and the experimental results verify the theoretical analysis well.
Wireless electric current sensing via integrating a magnetic–piezoelectric cantilever with a microstrip antenna
Authors: Cao Xi , Tian Xiao‐Jian , Wang Dong F.
Published: August 2017

This work for the first time presents a wireless electric current sensor via integrating a magnetic–piezoelectric cantilever and a trapezoidal‐structured microstrip antenna. The wireless current sensor system, consisting of both the magnetic–piezoelectric cantilever for measuring electric currents and the trapezoidal‐structured microstrip antenna for transmitting output voltages, are designed and integrated for demonstration, at an operating frequency of 3 GHz with the lowest return loss. Although output errors of 2–7% are observed for output voltage range of 88–116 mV, the signal transmission measurement demonstrates that the proposed integration is experimentally feasible and effective. Owing to the ultra‐wideband (2–11 GHz) and low‐power consumption of the integrated microstrip antenna, the proposed integration is expected to be applicable to various kinds of wireless sensor nodes of different frequencies or multi‐sensors monitoring systems.
Copper-Mediated Synthesis of Monofluoro Aryl Acetates via
Decarboxylative Cross-Coupling
Authors: Fahandej-Sadi Anis , Lundgren Rylan
Published: August 2017

We report the Cu-promoted oxidative cross-coupling of α-fluoromalonate half-esters and aryl boron reagents to deliver mono­fluoro α-aryl acetates under mild conditions (in air at room temperature). The reaction uses a simple, readily available monofluorinated building block to generate arylated compounds with functional groups that are not easily tolerated by existing methods, such as aryl bromides, iodides, pyridines, and pyrimidines.
Synthesis of the Verapamil Intermediate through the Quaternary Carbon-Constructing Allylic Substitution
Authors: Kobayashi Yuichi , Saeki Ryohei , Nanba Yutaro , Suganuma Yuta , Morita Masao , Nishimura Keita
Published: August 2017

In the present study, the key secondary allylic picolinate was synthesized via Pd(PPh3)4-catalyzed coupling of the TBS ether of (R,Z)-4-iodo-5-methylhex-3-en-2-ol with allyl-MgBr. Allylic substitution of the picolinate with the copper reagent derived from 3,4-(MeO)2C6H3MgBr and Cu(acac)2 in a 2:1 ratio afforded the anti SN2′ product with complete chirality transfer and 91% regioselectivity. Synthetic manipulation of the olefin moiety led to the nitrile group, generating the intermediate for the synthesis of (S)-verapamil.
Efficient Access to Chromeno[4,3-b]quinolines Related to Dependensin
Authors: Kumar Naresh , Dobrowolski Jeremy , Fraser Benjamin , Bhadbhade Mohan , Black David
Published: August 2017

We report a robust synthesis of novel chromeno[4,3-b]quinoline derivatives structurally similar to the natural product dependensin. The target compounds are accessed through the acid-catalysed condensation of 2-aminoacetophenones or 2-aminochalcones with substituted flavanones, which are in turn obtained from 2-hydroxyacetophenones and benzaldehydes.
Fusion Rates of Intervertebral Polyetheretherketone and Titanium Cages without Bone Grafting in Posterior Interbody Lumbar Fusion Surgery for Degenerative Lumbar Instability
Authors: Wrangel Christof , Karakoyun Ali , Buchholz Kaye-Marie , Süss Olaf , Kombos Theodoros , Woitzik Johannes , Vajkoczy Peter , Czabanka Marcus
Published: August 2017

Background Posterior lumbar interbody fusion (PLIF) surgery is a commonly used procedure for degenerative lumbar instability. Locally harvested bone is usually inserted into intervertebral cages to increase fusion rate. The fusion rate without bone application remains unknown. Our aim was to analyze retrospectively the fusion rates of intervertebral polyetheretherketone (PEEK) and titanium cages in PLIF surgery that were implanted without bone grafting using three-dimensional computed tomography (CT) scanning.

Material and Methods Forty patients (age 43–83 years) with mono- or bisegmental degenerative instability were included. PEEK cages were used in 28 segments (25 patients), and titanium cages were used in 17 segments (15 patients) undergoing PLIF surgery plus pedicle screws. The primary outcome parameter was radiologic fusion rate measured by CT at follow-up. Secondary parameters included rate of implant failure and adjacent segment disease.

Results No difference in mean age between groups was identified (PEEK: 69 ± 10 years; titanium: 62 ± 13 years). Mean follow-up was 39 ± 13 months in PEEK and 24 ± 12 months in the titanium group. Radiologic fusion rate was 32% of operated segments in PEEK and 53% in the titanium group. Screw loosening/adjacent-level disease was observed in 8% and 8% in the PEEK group and in 0% and 7% in the titanium group, respectively.

Conclusion Radiologic fusion rates of PEEK and titanium cages without bone grafting is low in PLIF surgery, and therefore bone grafting should be performed if possible. Rate of implant failure and adjacent-level disease remains low despite reduced osseous fusion in the operated segments.
Application of an Iliac Osteocutaneous and Fabricated Chimeric Iliac Osteocutaneous Flap for Foot and Ankle Reconstruction
Authors: Pan Zhao , Jiang Ping , Xue Shan , Wang Jian
Published: August 2017

Background As understanding of the blood supply by superficial circumflex iliac artery (SCIA) to the skin and iliac bone has improved and the use of a perforator flap has become accepted, most previous drawbacks of SICA iliac osteocutaneous flaps, such as bulky flap, small diameter, and inadequate blood supply to bone, can now be overcome. Here, the authors present their experience of using such flaps for the reconstruction of complex defects in the foot and ankle with a focus on feasibility and safety.

Methods A retrospective review of patients who underwent foot and ankle reconstruction using an SCIA iliac osteocutaneous flap between 2010 and 2015 was performed to assess outcomes.

Results Four patients who underwent treatment with SCIA iliac osteocutaneous flaps and eight patients treated with fabricated chimeric iliac osteocutaneous flaps were identified. The iliac segment size ranged from 1 × 3 × 0.7 to 3 × 6 × 1 cm and the skin paddle size ranged from 1 × 4 to 8 × 16 cm. All flaps survived uneventfully except for marginal necrosis in one anterolateral thigh (ALT) flap and one iliac osteocutaneous flap. The median time to bone union was 4 months. All patients were able to walk in normal footwear and none developed significant complications at the donor site.

Conclusion The use of free SCIA iliac osteocutaneous and fabricated chimeric iliac osteocutaneous flaps provides an alternative for treating small- and medium-sized bone defects (smaller than 8 cm) along with soft tissue defects in the foot and ankle region.
Tale of Two Patent Ductus Arteriosus Severity Scores: Similarities and Differences
Authors: Fink Daniel , El-Khuffash Afif , McNamara Patrick , Nitzan Itamar , Hammerman Cathy
Published: August 2017

Introduction Several echocardiographic scoring systems have been developed to assess the severity of patent ductus arteriosus (PDA) shunting in preterm infants.

Objective The objective of this study was to compare the ability of two different scoring systems to evaluate the hemodynamic significance of the PDA and to predict long-term PDA-associated morbidities.

Subjects El-Khuffash cohort (previously described) was derived from a multicenter, prospective, observational study conducted in tertiary neonatal intensive care units in Ireland, Canada, and Australia.

Results A total of 141 infants with a mean gestational age of 26 ± 1.4 weeks and a mean birth weight of 952 ± 235 g were evaluated on day 2 of life. The two scores were well correlated with each other and both scores positively predicted chronic lung disease/death in this population.

Conclusion There appears to be an overall stepwise progression in the incidence of poor outcome parameters from “closed” to “borderline” to “hemodynamically significant” PDA. Both the El-Khuffash and Shaare Zedek scores are predictive of PDA-associated morbidities.
Gesellschaft für Phytotherapie e.V. startete Fortbildungsreihe 2017 / 2018 für Ärzte und Apotheker
Authors: Nieber Karen
Published: August 2017

Nachdem 2015 / 2016 die ersten 4 Module der Fortbildungsreihe „Phytopharmaka und Phytotherapie“ erfolgreich durchgeführt wurden und 11 Teilnehmer ihr Zertifikat „Phytotherapeut“ (siehe Zeitschrift für Phytotherapie 2 / 2017) erhielten, fand das 1. Modul der neuen Serie vom 31.3.–2.4.2017 wiederum im Lindner Sport & Aktiv Hotel Kranichhöhe, Much / Bergisches Land statt, an dem 13 Teilnehmer begrüßt werden konnten.
Perspective: Surface freezing in water: A nexus of experiments and simulations
Authors: Haji-Akbari Amir , Debenedetti Pablo G.
Published: August 2017

Surface freezing is a phenomenon in which crystallization is enhanced at a vapor-liquid interface. In some systems, such as n-alkanes, this enhancement is dramatic and results in the formation of a crystalline layer at the free interface even at temperatures slightly above the equilibrium bulk freezing temperature. There are, however, systems in which the enhancement is purely kinetic and only involves faster nucleation at or near the interface. The first, thermodynamic, type of surface freezing is easier to confirm in experiments, requiring only the verification of the existence of crystalline order at the interface. The second, kinetic, type of surface freezing is far more difficult to prove experimentally. One material that is suspected of undergoing the second type of surface freezing is liquid water. Despite strong indications that the freezing of liquid water is kinetically enhanced at vapor-liquid interfaces, the findings are far from conclusive, and the topic remains controversial. In this perspective, we present a simple thermodynamic framework to understand conceptually and distinguish these two types of surface freezing. We then briefly survey fifteen years of experimental and computational work aimed at elucidating the surface freezing conundrum in water.
A comparison of non-local electron transport models for laser-plasmas relevant to inertial confinement fusion
Authors: Sherlock M. , Brodrick J. P. , Ridgers C. P.
Published: August 2017

We compare the reduced non-local electron transport model developed by Schurtz et al. [Phys. Plasmas 7, 4238 (2000)] to Vlasov-Fokker-Planck simulations. Two new test cases are considered: the propagation of a heat wave through a high density region into a lower density gas, and a one-dimensional hohlraum ablation problem. We find that the reduced model reproduces the peak heat flux well in the ablation region but significantly over-predicts the coronal preheat. The suitability of the reduced model for computing non-local transport effects other than thermal conductivity is considered by comparing the computed distribution function to the Vlasov-Fokker-Planck distribution function. It is shown that even when the reduced model reproduces the correct heat flux, the distribution function is significantly different to the Vlasov-Fokker-Planck prediction. Two simple modifications are considered which improve agreement between models in the coronal region.
Nonlinear gyrokinetic simulation of ion temperature gradient turbulence based on a numerical Lie-transform perturbation method
Authors: Xu Yingfeng , Ye Lei , Dai Zongliang , Xiao Xiaotao , Wang Shaojie
Published: August 2017

The electrostatic gyrokinetic nonlinear turbulence code NLT, which is based on a numerical Lie-transform perturbation method, is developed. For improving the computational efficiency and avoiding the numerical instabilities, field-aligned coordinates and a Fourier filter are adopted in the NLT code. Nonlinear tests of the ion temperature gradient driven turbulence with adiabatic electrons are performed for verifying the NLT code by comparing with other gyrokinetic codes. The time evolution of the ion heat diffusivity and the relation between the ion heat diffusivity and the ion temperature gradient are compared in the nonlinear tests. Good agreements are achieved from the nonlinear benchmarks between the NLT code and other codes. The mode structures of the perturbed electric potential representing different phases have been simulated.
Experiment study and FEM simulation on erythrocytes under linear stretching of optical micromanipulation
Authors: Liu Ying , Song Huadong , Zhu Panpan , Lu Hao , Tang Qi
Published: August 2017

The elasticity of erythrocytes is an important criterion to evaluate the quality of blood. This paper presents a novel research on erythrocytes’ elasticity with the application of optical tweezers and the finite element method (FEM) during blood storage. In this work, the erythrocytes with different in vitro times were linearly stretched by trapping force using optical tweezers and the time dependent elasticity of erythrocytes was investigated. The experimental results indicate that the membrane shear moduli of erythrocytes increased with the increasing in vitro time, namely the elasticity was decreasing. Simultaneously, an erythrocyte shell model with two parameters (membrane thickness h and membrane shear modulus H) was built to simulate the linear stretching states of erythrocytes by the FEM, and the simulations conform to the results obtained in the experiment. The evolution process was found that the erythrocytes membrane thicknesses were decreasing. The analysis assumes that the partial proteins and lipid bilayer of erythrocyte membrane were decomposed during the in vitro preservation of blood, which results in thin thickness, weak bending resistance, and losing elasticity of erythrocyte membrane. This study implies that the FEM can be employed to investigate the inward mechanical property changes of erythrocyte in different environments, which also can be a guideline for studying the erythrocyte mechanical state suffered from different diseases.
High temperature electrons exhausted from rf plasma sources along a magnetic nozzle
Authors: Takahashi Kazunori , Akahoshi Hikaru , Charles Christine , Boswell Rod W. , Ando Akira
Published: August 2017

Two dimensional profiles of electron temperature are measured inside and downstream of a radiofrequency plasma thruster source having a magnetic nozzle and being immersed in vacuum. The temperature is estimated from the slope of the fully swept I-V characteristics of a Langmuir probe acquired at each spatial position and with the assumption of a Maxwellian distribution. The results show that the peripheral high temperature electrons in the magnetic nozzle originate from the upstream antenna location and are transported along the “connecting” magnetic field lines. Two-dimensional measurements of electron energy probability functions are also carried out in a second simplified laboratory device consisting of the source contiguously connected to the diffusion chamber: again the high temperature electrons are detected along the magnetic field lines intersecting the wall at the antenna location, even when the antenna location is shifted along the main axis. These results demonstrate that the peripheral energetic electrons in the magnetic nozzle mirror those created in the source tube.
Exposing high-energy surfaces by rapid-anneal solid phase epitaxy
Authors: Wang Y. , Song Y. , Peng R. , Herklotz A. , Chisholm M. F. , Wu Z. L. , Ward T. Z. , Weitering H. H. , Snijders P. C.
Published: August 2017

The functional design of transition metal oxide heterostructures depends critically on the growth of atomically flat epitaxial thin films. Often, improved functionality is expected for heterostructures and surfaces with orientations that do not have the lowest surface free energy. For example, crystal faces with a high surface free energy, such as rutile (001) planes, frequently exhibit higher catalytic activities but are correspondingly harder to synthesize due to faceting transitions. Here we propose a broadly applicable rapid-anneal solid phase epitaxial synthesis approach for the creation of nanometer thin, high surface free energy oxide heterostructures that are atomically flat. We demonstrate its efficacy by synthesizing atomically flat epitaxial RuO2(001) and TiO2(001) model systems. The former have a superior oxygen evolution activity, quantified by their lower onset potential and higher current density, relative to that of more common RuO2(110) films.
Counterevidence to the ion hammering scenario as a driving force for the shape elongation of embedded nanoparticles
Authors: Amekura H. , Okubo N. , Tsuya D. , Ishikawa N.
Published: August 2017

Counterevidence is provided in the ion-hammering scenario as a driving force for the shape elongation of embedded nanoparticles (NPs) under swift heavy ion irradiation (SHII). Ion-induced compaction and the hammering, which are both induced in silica under SHII, dominate at low and high fluences, respectively, causing a crossover between them around a fluence of ∼4 × 1012 ions/cm2. Nevertheless, the shape elongation of NPs detected by the optical dichroism exhibits nearly linear dependence in a wide fluence range between ∼1 × 1011 and 2 × 1013 ions/cm2, indicating that the hammering does not play an important role.
Dynamical transition in molecular glasses and proteins observed by spin relaxation of nitroxide spin probes and labels
Authors: Golysheva Elena A. , Shevelev Georgiy Yu. , Dzuba Sergei A.
Published: August 2017

In glassy substances and biological media, dynamical transitions are observed in neutron scattering that manifests itself as deviations of the translational mean-squared displacement, 〈x2〉, of hydrogen atoms from harmonic dynamics. In biological media, the deviation occurs at two temperature intervals, at ∼100–150 K and at ∼170–230 K, and it is attributed to the motion of methyl groups in the former case and to the transition from harmonic to anharmonic or diffusive motions in the latter case. In this work, electron spin echo (ESE) spectroscopy—a pulsed version of electron paramagnetic resonance—is applied to study the spin relaxation of nitroxide spin probes and labels introduced in molecular glass former o-terphenyl and in protein lysozyme. The anisotropic contribution to the rate of the two-pulse ESE decay, ΔW, is induced by spin relaxation appearing because of restricted orientational stochastic molecular motion; it is proportional to 〈α2〉τc, where 〈α2〉 is the mean-squared angle of reorientation of the nitroxide molecule around the equilibrium position and τc is the correlation time of reorientation. The ESE time window allows us to study motions with τc < 10−7 s. For glassy o-terphenyl, the 〈α2〉τc temperature dependence shows a transition near 240 K, which is in agreement with the literature data on 〈x2〉. For spin probes of essentially different size, the obtained data were found to be close, which evidences that motion is cooperative, involving a nanocluster of several neighboring molecules. For the dry lysozyme, the 〈α2〉τc values below 260 K were found to linearly depend on the temperature in the same way as it was observed in neutron scattering for 〈x2〉. As spin relaxation is influenced only by stochastic motion, the harmonic motions seen in ESE must be overdamped. In the hydrated lysozyme, ESE data show transitions near 130 K for all nitroxides, near 160 K for the probe located in the hydration layer, and near 180 K for the label in the protein interior. For this system, the two latter transitions are not observed in neutron scattering. The ESE-detected transitions are suggested to be related with water dynamics in the nearest hydration shell: with water glass transition near 130 K and with the onset of overall water molecular reorientations near 180 K; the disagreement with neutron scattering is ascribed to the larger time window for ESE-detected motions.
Investigation of the interaction dynamics of a pair of laser-induced bubbles generated at the same time through double-exposure strobe method and numerical simulations
Authors: Han Bing , Liu Liu , Ni Xiao-Wu
Published: August 2017

In order to understand the interaction dynamics of a pair of laser-induced bubbles, a double-exposure strobe photography experimental setup is build up to study the temporal evolution of the bubble pairs and to measure the transient bubble-interface moving speed. The interaction mechanisms of the bubble pairs are discussed together with the numerical results obtained through OpenFOAM. It is shown that the direction and the velocity of the jetting could be controlled by the relative size and the relative initiation distance of the bubble pair, when the bubbles are generated at the same time, i.e., in-phase. The liquid jet is considered to be a penetrating jet. The jet is originated from the smaller bubble and clearly protruding outside of the bigger bubble. The parameter space of the relative size and the initiation distance of the bubble pair allowing the formation of the penetrating jet are very narrow. It is concluded that the liquid jet induced by the bubble interactions resulted from the collapse and the rebound of the smaller bubble nearby the bigger bubble. This is defined as the “catapult effect.” Such a directional liquid transportation is a promising tool as a micro-injector or a micro-pump. The investigation results could be also supplementary to the understandings of the bubble dynamics.
Effects of orthogonal rotating electric fields on electrospinning process
Authors: Lauricella M. , Cipolletta F. , Pontrelli G. , Pisignano D. , Succi S.
Published: August 2017

Electrospinning is a nanotechnology process whereby an external electric field is used to accelerate and stretch a charged polymer jet, so as to produce fibers with nanoscale diameters. In quest of a further reduction in the cross section of electrified jets hence of a better control on the morphology of the resulting electrospun fibers, we explore the effects of an external rotating electric field orthogonal to the jet direction. Through intensive particle simulations, it is shown that by a proper tuning of the electric field amplitude and frequency, a reduction of up to a 30% in the aforementioned radius can be obtained, thereby opening new perspectives in the design of future ultra-thin electrospun fibers. Applications can be envisaged in the fields of nanophotonic components as well as for designing new and improved filtration materials.
Unsteady aerodynamic force mechanisms of a hoverfly hovering with a short stroke-amplitude
Authors: Zhu Hao Jie , Sun Mao
Published: August 2017

Hovering insects require a rather large lift coefficient. Many insects hover with a large stroke amplitude (120°-170°), and it has been found that the high lift is mainly produced by the delayed-stall mechanism. However, some insects hover with a small stroke amplitude (e.g., 65°). The delayed-stall mechanism might not work for these insects because the wings travel only a very short distance in a stroke, and other aerodynamic mechanisms must be operating. Here we explore the aerodynamic mechanisms of a hoverfly hovering with an inclined stroke plane and a small stroke amplitude (65.6°). The Navier-Stokes equations are numerically solved to give the flows and forces and the theory of vorticity dynamics used to reveal the aerodynamic mechanisms. The majority of the weight-supporting vertical force is produced in the mid portion of the downstroke, a short period (about 26% of the stroke cycle) in which the vertical force coefficient is larger than 4. The force is produced using a new mechanism, the “paddling mechanism.” During the short period, the wing moves rapidly downward and forward at a large angle of attack (about 48°), and strong counter clockwise vorticity is produced continuously at the trailing edge and clockwise vorticity at the leading edge, resulting in a large time rate of change in the first moment of vorticity, hence the large aerodynamic force. It is interesting to note that with the well known delayed stall mechanism, the force is produced by the relative motion of two vortices of opposite sign, while in the “paddling mechanism,” it is produced by generating new vortices of opposite sign at different locations.
Identification of coherent structures in the flow past a NACA0012 airfoil via proper orthogonal decomposition
Authors: Ribeiro Jean Hélder Marques , Wolf William Roberto
Published: August 2017

Proper orthogonal decomposition, POD, is employed to identify coherent structures in the turbulent flow past a NACA0012 airfoil. An analysis of different POD techniques is presented including the standard snapshot method, the spectral POD (SPOD) method, and a Fourier-POD implementation combined with the SPOD. The latter technique is viable once the present turbulent flow has a homogeneous direction along the airfoil span. An assessment of different vector norms and filter functions employed in the POD reconstruction is presented. The evaluation of the several POD techniques allows the investigation of the physics of the current turbulent flow including the observation of coherent structures and their relation to the airfoil noise generation mechanisms. The SPOD technique is applied assuming periodic and non-periodic temporal signals in the construction of the covariance matrix. Although it slightly alters the spectrum of the POD singular values, the periodic SPOD considerably reduces the noise observed in the singular vectors. The application of the Gaussian filtering allows an enhanced control in the response of the SPOD when compared with a square-box filter. The present POD reconstructions employ norms based on kinetic energy and pressure. For both norms, two-dimensional coherent structures are observed along the turbulent boundary layer and wake regions for the first pair of modes. These structures have a spectral content at the same frequency of the tonal noise radiation by the airfoil. The POD analysis also allows the identification of further coherent structures in the present flow. The kinetic energy norm is able to reconstruct low-frequency structures in the flow field for higher POD modes, while the pressure norm reconstructs high-frequency structures. This behavior is related to the physics captured by each POD norm in the present turbulent flow.
Near-infrared linewidth narrowing in plasmonic Fano-resonant metamaterials via tuning of multipole contributions
Authors: Lim Wen Xiang , Han Song , Gupta Manoj , MacDonald Kevin F. , Singh Ranjan
Published: August 2017

We report on an experimental and computational (multipole decomposition) study of Fano resonance modes in complementary near-IR plasmonic metamaterials. Resonance wavelengths and linewidths can be controlled by changing the symmetry of the unit cell so as to manipulate the balance among multipole contributions. In the present case, geometrically inverting one half of a four-slot (paired asymmetric double bar) unit cell design changes the relative magnitude of magnetic quadrupole and toroidal dipole contributions leading to the enhanced quality factor, figure of merit, and spectral tuning of the plasmonic Fano resonance.
Simulation of photo-excited adenine in water with a hierarchy of equations of motion approach
Authors: Dijkstra Arend G. , Prokhorenko Valentyn I.
Published: August 2017

We present a theoretical method to simulate the electronic dynamics and two-dimensional ultraviolet spectra of the nucleobase adenine in water. The method is an extension of the hierarchy of equations of motion approach to treat a model with one or more conical intersections. The application to adenine shows that a two-level model with a direct conical intersection between the optically bright state and the ground state, generating a hot ground state, is not consistent with experimental observations. This supports a three-level model for the decay of electronically excited adenine in water as was previously proposed in the work of V. I. Prokhorenko et al. [J. Phys. Chem. Lett. 7, 4445 (2016)].
Anomalous critical slowdown at a first order phase transition in single polymer chains
Authors: Zhang Shuangshuang , Qi Shuanhu , Klushin Leonid I. , Skvortsov Alexander M. , Yan Dadong , Schmid Friederike
Published: August 2017

Using Brownian dynamics, we study the dynamical behavior of a polymer grafted onto an adhesive surface close to the mechanically induced adsorption-stretching transition. Even though the transition is first order (in the infinite chain length limit, the stretching degree of the chain jumps discontinuously), the characteristic relaxation time is found to grow according to a power law as the transition point is approached. We present a dynamic effective interface model which reproduces these observations and provides an excellent quantitative description of the simulation data. The generic nature of the theoretical model suggests that the unconventional mixing of features that are characteristic for first-order transitions (a jump in an order parameter) and features that are characteristic of critical points (an anomalous slowdown) may be a common phenomenon in force-driven phase transitions of macromolecules.
A 5-μm pitch charge-coupled device optimized for resonant inelastic soft X-ray scattering
Authors: Andresen N. C. , Denes P. , Goldschmidt A. , Joseph J. , Karcher A. , Tindall C. S.
Published: August 2017

We have developed a charge-coupled device (CCD) with 5 μm × 45 μm pixels on high-resistivity silicon. The fully depleted 200 μm-thick silicon detector is back-illuminated through a 10 nm-thick in situ doped polysilicon window and is thus highly efficient for soft through >8 keV hard X-rays. The device described here is a 1.5 megapixel CCD with 2496 × 620 pixels. The pixel and camera geometry was optimized for Resonant Inelastic X-ray Scattering (RIXS) and is particularly advantageous for spectrometers with limited arm lengths. In this article, we describe the device architecture, construction and operation, and its performance during tests at the Advance Light Source (ALS) 8.0.1 RIXS beamline. The improved spectroscopic performance, when compared with a current standard commercial camera, is demonstrated with a ∼280 eV (CK) X-ray beam on a graphite sample. Readout noise is typically 3-6 electrons and the point spread function for soft CK X-rays in the 5 μm direction is 4.0 μm ± 0.2 μm. The measured quantum efficiency of the CCD is greater than 75% in the range from 200 eV to 1 keV.
Magnetic field tunable vortex diode made of YBa2Cu3O7−δ Josephson junction asymmetrical arrays
Authors: Chesca Boris , John Daniel , Pollett Richard , Gaifullin Marat , Cox Jonathan , Mellor Christopher J. , Savel'ev Sergey
Published: August 2017

Several Josephson ratchets designed as asymmetrically structured parallel-series arrays of Josephson junctions made of YBa2Cu3O7−δ have been fabricated. From the current-voltage characteristics measured for various values of applied magnetic field, B, in the temperature range of 10–89 K, we demonstrate that the devices work as magnetic field-tunable highly reversible vortex diodes. Thus, at 89 K, the ratchet efficiency η could be reversed from +60% to −60% with a change in B as small as 3 μT. By decreasing the operation temperature, η improves up to −95% at 10 K while the dynamics in the B-tunability degrades. The ratchet designs we propose here can be used to control unidirectional vortex flow vortices in superconducting devices as well as building integrated nano-magnetic sensors. Numerical simulations qualitatively confirm our experimental findings and also provide insight into the related and more general problem of the control of the transport of nano/quantum objects in thin films.
Implementation of dynamic dual input multiple output logic gate via resonance in globally coupled Duffing oscillators
Authors: Venkatesh P. R. , Venkatesan A. , Lakshmanan M.
Published: August 2017

We have used a system of globally coupled double-well Duffing oscillators under an enhanced resonance condition to design and implement Dual Input Multiple Output (DIMO) logic gates. In order to enhance the resonance, the first oscillator in the globally coupled system alone is excited by two forces out of which one acts as a driving force and the other will be either sub-harmonic or super-harmonic in nature. We report that for an appropriate coupling strength, the second force coherently drives and enhances not only the amplitude of the weak first force to all the coupled systems but also drives and propagates the digital signals if any given to the first system. We then numerically confirm the propagation of any digital signal or square wave without any attenuation under an enhanced resonance condition for an amplitude greater than a threshold value. Further, we extend this idea for computing various logical operations and succeed in designing theoretically DIMO logic gates such as AND/NAND, OR/NOR gates with globally coupled systems.
Transition characteristics of low-pressure discharges in a hollow cathode
Authors: Fu Yangyang , Verboncoeur John P. , Christlieb Andrew J. , Wang Xinxin
Published: August 2017

Based on a two-dimensional (2-D) fluid model, the transition processes of discharges in a hollow cathode at low pressure are observed by changing three parameters, i.e., applied voltage U0, gas pressure p, and external circuit ballast resistance Rb. The voltage-current characteristic curves, electron density distributions, and electric potential distributions of different discharge operating points in a hollow cathode are obtained. The transition processes are characterized by the voltage-current characteristic curves, the electron density distributions, and the electrical potential distributions. The transition modes observed from the voltage-current characteristics include the low-current abnormal mode, normal mode, and high-current abnormal mode. Increasing the applied voltage U0 can have a similar effect on the discharge transition processes to decreasing the ballast resistance. By increasing U0 from 200 V to 500 V and decreasing Rb from 5000 kΩ to 100 kΩ independently, it is observed that the discharge transfers from the outside to the inside of the hollow cavity, thus forming the virtual anode potential. By increasing the gas pressure p from 50 Pa to 5 kPa, the discharge also moves into the hollow cavity from the outside; however, a further increase in the gas pressure leads to the discharge escaping from the hollow cavity. Simulation results and characterizations for different parameters are presented for the transition properties of low-pressure discharges in a hollow cathode. It is verified that the hollow cathode discharge only exists under certain ranges of the above parameters.
Mode conversion enables optical pulling force in photonic crystal waveguides
Authors: Zhu Tongtong , Novitsky Andrey , Cao Yongyin , Mahdy M. R. C. , Wang Lin , Sun Fangkui , Jiang Zehui , Ding Weiqiang
Published: August 2017

We propose a robust scheme to achieve optical pulling force using the guiding modes supported in a hollow core double-mode photonic crystal waveguide instead of the structured optical beams in free space investigated earlier. The waveguide under consideration supports both the 0th order mode with a larger forward momentum and the 1st order mode with a smaller forward momentum. When the 1st order mode is launched, the scattering by the object inside the waveguide results in the conversion from the 1st order mode to the 0th order mode, thus creating the optical pulling force according to the conservation of linear momentum. We present the quantitative agreement between the results derived from the mode conversion analysis and those from rigorous simulation using the finite-difference in the time-domain numerical method. Importantly, the optical pulling scheme presented here is robust and broadband with naturally occurred lateral equilibriums and has a long manipulation range. Flexibilities of the current configuration make it valuable for the optical force tailoring and optical manipulation operation, especially in microfluidic channel systems.
Differential ghost imaging in time domain
Authors: O-oka Yoshiki , Fukatsu Susumu
Published: August 2017

Differential ghost imaging is attempted in time domain, i.e., temporal differential ghost imaging (TDGI), using pseudo-randomized light pulses and a temporal object consisting of no-return-to-zero bit patterns of varying duty. Evaluation of the signal-to-noise characteristics by taking into account errors due to false cross-correlation between the reference and the bucket detector readings indicates that the TDGI outperforms its non-differential counterpart, i.e., time-domain GI, in terms of consistently high and even duty-independent signal-to-noise ratios that are achieved.
Are Queensland brush-tailed phascogales different?
Authors: Edwards M. C.
Published: August 2017

Little is known about the basic biology of brush-tailed phascogales, Phascogale tapoatafa, in southern Queensland. Wild-caught phascogales, and museum and veterinary records were examined. Queensland phascogales are smaller than Victorian phascogales, but larger than Western Australian animals of the same subspecies.
Star-Shaped Copolymers Based on Poly(N-vinylcaprolactam) and their Use as Nanocarriers of Methotrexate
Authors: Cortez-Lemus Norma A. , Licea-Claverie Angel
Published: August 2017

Star-shaped poly(N-vinylcaprolactam)-block-poly(ethylhexylacrylate)-block-polyethylene glycol (PNVCL-b-PEHA-b-PEG) triblock copolymers and star-shaped poly(N-vinylcaprolactam)-block-polyethylene glycol (PNVCL-b-PEG) diblock copolymers were synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization. The resulting star block copolymers were characterized using 1H NMR and UV-vis spectroscopy, gel permeation chromatography, and dynamic light scattering. The star-shaped PNVCL-b-PEG and PNVCL-b-PEHA-b-PEG block copolymers self-assemble spontaneously into aggregates in water. The aggregates formed ranged from ~17 to 135 nm in diameter and were used to encapsulate methotrexate (MTX). It was observed that the aggregates from PNVCL-b-PEHA-b-PEG copolymers exhibited a higher drug loading and a lower release of MTX (19 wt-% and 54 %) as compared with star copolymers without PEHA (5 wt-% and 81 %) after 24 h at a temperature below their lower critical solution temperature values.
Croton blanchetianus modulates its morphophysiological responses to tolerate drought in a tropical dry forest
Authors: Mendes Keila R. , Granja João A. A. , Ometto Jean P. , Antonino Antônio C. D. , Menezes Rômulo S. C. , Pereira Eugênia C. , Pompelli Marcelo F.
Published: August 2017

An understanding of variations in morphophysiological leaf traits of plant models in dry tropical forests is essential for quantifying C fluxes from forest ecosystems in response to climate changes. The present study evaluated the influences of seasonal rainfall and different light conditions on the gas exchange, nutrients, organic compounds and morphological traits in Croton blanchetianus Baill. trees within a fragment of Caatinga forest. Stomatal conductance (gs) and net photosynthesis (PN) demonstrated variations within the diurnal cycle, with maximum values at approximately midday and minimum values at predawn. The PN and the diurnal integrated CO2 assimilation were lower during the dry season than in the rainy season. Water use efficiency was positively correlated with PN (r = 0.73) during the dry season only. However, the correlation between PN and gs was observed during the rainy season only (r = 0.60). Thus we demonstrated that C. blanchetianus has a remarkable ability to adapt to global climatic changes and could be considered a model in studies exploring water relationships in woody plants; consequently, this species may be important in future reforestation studies.
Development of fresh and vitrified agouti ovarian tissue after xenografting to ovariectomised severe combined immunodeficiency (SCID) mice
Authors: Praxedes Érica C. G. , Lima Gabriela L. , Bezerra Luana G. P. , Santos Fernanda A. , Bezerra Marcelo B. , Guerreiro Denise D. , Rodrigues Ana P. R. , Domingues Sheyla F. S. , Silva Alexandre R.
Published: August 2017

The aim of the present study was to evaluate the development of fresh and vitrified agouti ovarian tissue after xenografting to C57Bl/6 severe combined immunodeficiency (SCID) female mice. Ovaries were obtained from five female agoutis and divided into 16 fragments. Five fragments were transplanted immediately to ovariectomised SCID mice and the others were vitrified, stored for 2 weeks and transplanted only after rewarming. Tissue fragments were transplanted under the kidney capsule in recipients. The return of ovarian activity in recipients was monitored by the observation of external signs of oestrus and vaginal cytology over a period of 40 days after transplantation, after which the grafts were removed and evaluated for morphology, cell proliferation and the occurrence of DNA fragmentation. Ovarian activity returned in four of five mice that received fresh ovarian tissue from agoutis and in one of six mice that had received vitrified tissue a mean (± s.e.m.) 20.6 ± 8.6 days after xenotransplantation. After graft removal, a predominance of primordial and primary follicles was observed in all grafts. Vitrification reduced cell proliferation and increased the occurrence of DNA fragmentation in grafted agouti ovarian tissue. In conclusion, the present study demonstrates that xenografted agouti ovarian tissue, fresh or vitrified, is able to promote the return of ovarian activity in ovariectomised SCID C57B1/6 mice. However, improvements to vitrification protocols for agouti ovarian tissue are necessary.
An experimental study on thermal radiation of fire whirl
Authors: Wang Pengfei , Liu Naian , Bai Yueling , Zhang Linhe , Satoh Kohyu , Liu Xuanya
Published: August 2017

Fire whirl is frequently observed in wildland fires, and may cause serious difficulty in firefighting owing to its significant turbulent flow. In this paper, the radiation of fire whirl is investigated through experiments using a fire whirl facility made up of an air curtain apparatus, with five different sizes of n-heptane pools (25, 30, 35, 40 and 45 cm). The flame contour was extracted by image processing. By using infrared methods, the flame emissivity of fire whirl at different heights for different pool diameters was measured, and thereby a correlation was developed between the flame emissivity and the flame diameter. The soot volume fraction in the luminous flame is estimated to range within 2.5 × 10−6 to 4.0 × 10−6, much higher than that of general heptane pool fires, which provides an explanation of the higher flame emissivity of fire whirl. The emissive power profile v. normalised height is deduced from flame emissivity and flame temperature data. A multizone flame model (in which each zone is assumed as a grey body) is used, based on the measured data of flame emissivity, to predict the radiation of fire whirl. Comparison between the predicted and measured data of radiative flux shows good agreement.