bluuebunny/crossref_metadata_2025 huggingface dataset:
New insights into the adaptive transcriptional response to nitrogen starvation in Escherichia coli
Authors: Switzer Amy , Brown Daniel R. , Wigneshweraraj Sivaramesh
Published: December 2018

Bacterial adaptive responses to biotic and abiotic stresses often involve large-scale reprogramming of the transcriptome. Since nitrogen is an essential component of the bacterial cell, the transcriptional basis of the adaptive response to nitrogen starvation has been well studied. The adaptive response to N starvation in Escherichia coli is primarily a ‘scavenging response’, which results in the transcription of genes required for the transport and catabolism of nitrogenous compounds. However, recent genome-scale studies have begun to uncover and expand some of the intricate regulatory complexities that underpin the adaptive transcriptional response to nitrogen starvation in E. coli. The purpose of this review is to highlight some of these new developments.
Multimodal medical image registration via common representations learning and differentiable geometric constraints
Authors: Liu Cong , Ma Longhua , Lu Zheming , Jin Xiance , Xu Jingyun
Published: December 2018

Multimodal medical image registration remains a challenging problem when strong appearance variations and imprecise alignment exist in images. Previous deep network approaches cannot handle such a high degree of variability and prohibit the use of strong geometric constraints. The authors introduce a novel deep architecture that not only produces image representations that are well‐suited for this challenging task, but also leverages knowledge of the geometry constraints for robust registration. By enforcing the representations of different modalities living in a common semantic space, they obtain convolutional features tending to respond to object parts consistently across modality. This yields a unique description for all object fragments and allows the end user to know the model's decision process, whereas most existing models remain unclear and difficult to explain. By using the differentiable spatial transformer to compensate transform, they integrate geometric consensus into the cost function to enable end‐to‐end model optimisation which has not yet been exploited before. The authors evaluate their method on a very challenging medical image dataset. Experiments demonstrate that the proposed method provides a plausible representation and outperforms state‐of‐the‐art approaches by a significant margin.
Low‐power, high‐speed output buffer with shared‐TIA for ultra‐large IRFPAs
Authors: Huang Zhaofeng , Niu Yuze , Lu Wengao , Zhu Yajun , Zhang Shengdong
Published: December 2018

In this Letter, a low‐power, high‐speed output buffer for ultra‐large infrared focal plane arrays (IRFPAs) is proposed. This buffer adopts a shared trans‐impedance amplifier structure, which reduces parasitic resistance and capacitance of column‐level bus. A 1280 × 1024 array readout integrated circuit with 20 MHz output frequency is designed for cooled infrared detector using this novel structure. The chip has been realised with 0.35 μm 1P4M CMOS process and power consumption of the proposed single output buffer is 3.83 mW. Though the presented circuit has been designed for this design, it shows great potential to be employed in most ultra‐large readout integrated circuits.
Bayesian approach to identify Hammerstein–Wiener non‐linear model in presence of noise and disturbance
Authors: Esmaeilani Leili , Ghaisari Jafar , Bagherzadeh Mohammad Ali
Published: December 2018

In this study, a recursive algorithm is presented for identification of both linear and non‐linear blocks of the Hammerstein–Wiener (H–W) models. An iterative sampling schema is used, along with non‐parametric describing of non‐linear functions by Gaussian processes, to consider the Gaussian distributed noise and disturbances. Different aspects of solving the H–W problem are discussed, covering the formulation of the non‐linear functions, uniqueness assumptions and the effect of stochastic disturbances on the solution. The proposed method is used to identify an H–W model for the systems encounter all possible disturbances consists of input and output measurement noise, disturbances in the linear block and the additive disturbances to the interconnecting signals of the linear and non‐linear blocks. Effectiveness and simplicity of the method are shown by an example. The results show that the accuracy of the proposed method is acceptable in presence of noise and disturbances.
Detector‐based approach for H filtering of Markov jump linear systems with partial mode information
Authors: Rodrigues Caio César Graciani , Todorov Marcos Garcia , Fragoso Marcelo Dutra
Published: December 2018

The goal of this study is to present new results for filtering for continuous‐time Markov jump linear systems with partial information on the jumping parameter. The central hypothesis considered here is the existence of a suitable detector, which provides measurements of the Markov chain. Besides the interest in its own right, this detector‐based approach allows us to treat, in a unified manner, the cases with complete observations, no information and cluster observations of the jumping process as particular scenarios. The main result comprises a method for designing a mean square stable linear filter by using the information given by the detector, in the limit case where the sensors respond at much faster rates than the system dynamics. The proposed filter design is given in terms of parameterised linear matrix inequalities (LMIs), which are tackled through an iterative LMI‐based algorithm. Furthermore, the result is applied to the state estimation of an unmanned aerial vehicle model.
Predictive cruise control of connected and autonomous vehicles via reinforcement learning
Authors: Gao Weinan , Odekunle Adedapo , Chen Yunfeng , Jiang Zhong‐Ping
Published: December 2018

Predictive cruise control concerns designing controllers for autonomous vehicles using the broadcasted information from the traffic lights such that the idle time around the intersection can be reduced. This study proposes a novel adaptive optimal control approach based on reinforcement learning to solve the predictive cruise control problem of a platoon of connected and autonomous vehicles. First, the reference velocity is determined for each autonomous vehicle in the platoon. Second, a data‐driven adaptive optimal control algorithm is developed to estimate the gains of the desired distributed optimal controllers without the exact knowledge of system dynamics. The obtained controller is able to regulate the headway, velocity, and acceleration of each vehicle in a suboptimal sense. The goal of trip time reduction is achieved without compromising vehicle safety and passenger comfort. Numerical simulations are presented to validate the efficacy of the proposed methodology.
Fast video‐based queue length detection approach for self‐organising traffic control
Authors: Jiang Tao , Cai Mingdai , Zhang Yulong , Jia Xiaojie
Published: December 2018

With the development of traffic control theory, self‐organising control has become one of the most promising techniques for traffic control. Among the various parameters of self‐organising control, the queue length (number of vehicles) is a key one. Compared to the approaches using other detectors, vision‐based approaches have a greater potential in queue length detection. However, the complicated traffic conditions (such as the changeable weather and the vehicle occlusion) and the large calculation of image processing have posed great challenges to the real‐time application. Here, a fast video‐based queue length detection approach is proposed. For each lane, according to the level of traffic congestion evaluated by the foreground area ratio, the corresponding vehicle counting method is adopted. When the traffic is determined congested, a fast area‐based method for estimating the number of vehicles is adopted. Otherwise, a fast vehicle detection and counting method combining background difference and Adaboost classifier is adopted. The experiment results demonstrate that the proposed approach can handle actual traffic environment and has great potential for real‐time application.
Frequency sensitivity analysis of dynamic demand response in wind farm integrated power system
Authors: Pradhan Chittaranjan , Bhende Chandrashekhar Narayan , Srivastava Anurag K.
Published: December 2018

Demand response (DR) has emerged as a very important part of the future smart grid to enhance the power system reliability and frequency stability. This study presents the benefits of DR control and battery energy storage (BES) on frequency regulation in wind farm integrated power system. In this study, a generalised load frequency control model of a hybrid hierarchical DR control mechanism is developed by incorporating the inherent system parameters such as frequency dead‐band, aggregated generations/devices and communication time delay and so on. The mathematical formulation for frequency stability and sensitivity analysis are carried out with respect to the frequency change coefficient for switching OFF the DR devices and frequency regulation service shared by conventional supplementary control, DR and BES. The extensive simulation results are presented for system frequency response (SFR) to support the theoretical analysis. It is found that DR has a significant effect to stabilise SFR. The observations drawn from analysis can be helpful for system operators/regional transmission organisation to investigate or plan for deciding the frequency threshold, minimum turn OFF time for individual DR devices, frequency coefficient factor and percentage share of frequency regulation services to restore the frequency quickly.
Improved secondary control for optimal total harmonic distortion compensation of parallel connected DGs in islanded microgrids
Authors: Andishgar Mohammad Hadi , Gholipour Eskandar , Hooshmand Rahmat‐Allah
Published: December 2018

This study proposes a two‐layer hierarchical control to actualize optimal total harmonic distortion (THD) compensation in different buses of parallel‐connected inverters in islanded microgrids which had not been studied so far. The proposed secondary layer is used to realize THD compensation of sensitive load bus (SLB) and make distributed generators (DGs) distribute the compensating efforts between them according to their rated capacity. It is noteworthy that improving THD at the SLB can lead to an increase in THD at local buses and/or DG terminals. Although the THD limitations of these buses are not as strict as the THD limitation of SLB, it is necessary to control them within their allowed range. This important problem is not well studied in the literature. A novel complementary part is designed and added to the secondary control to tune the compensation portion of each DG while the THD limitations in DG terminals and local buses are considered. The proposed method actualizes a multi‐level voltage quality control in multi‐bus islanded microgrids with parallel DGs through a simple yet effective solution. Furthermore, considering the DGs peak current limitation is added to the controller and a method for calculating this peak value is proposed.
Comprehensive review of IDMs in DG systems
Authors: Manikonda Santhosh K.G. , Gaonkar Dattatraya Narayan
Published: December 2018

Distributed generation (DG) offers solution to the ever increasing energy needs by generating energy at the consumer end, in most cases, by means of renewable energy sources. Islanding detection is an important aspect of interconnecting a DG to the utility. This study presents comprehensive review of various islanding detection techniques along with their relative advantages and disadvantages. A broad classification of islanding detection methods (IDMs) is laid out as classical methods, signal processing (SP)‐based methods, and computational intelligence‐based methods with a focus on SP‐based methods and computational intelligence‐based methods. The evolution of SP techniques used for islanding detection is presented along with the merits and shortcomings of each technique. Furthermore, the advent of computational intelligence methods based IDMs are discussed along with their merits and demerits. An insight into various islanding methods based on quantitative measures of performance indices such as detection time, detection accuracy, and efficiency are tabulated and presented. Finally, the prospective direction of research for IDMs is also presented.
Empirische Erfassung subjektiver Gesundheitsmerkmale am Beispiel der gesundheitsbezogenen Lebensqualität
Authors: Obbarius Alexander , Fischer Kathrin , Fischer Felix , Liegl Gregor , Obbarius Nina , Nolte Sandra , Rose Matthias
Published: December 2018

Gesundheitsbezogene Lebensqualität gewinnt als Zielparameter für verschiedene Akteure des Gesundheitswesens an Bedeutung, z. B. bei der Therapieevaluation von chronisch kranken
Patienten. In diesem Artikel beschreiben wir die unterschiedlichen Ebenen der „gesundheitsbezogenen Lebensqualität“, aktuelle Methoden zur Erfassung patientenberichteter
Gesundheitsmerkmale sowie moderne testtheoretische Ansätze und deren Anwendungsmöglichkeiten.
Ökonomische Betrachtung von Genexpressionstests beim Mammakarzinom am Beispiel des Oncotype DX®
Authors: Thiem Helena , Lux Michael , Rebscher Herbert , Potempa Christoph
Published: December 2018

Zielsetzung Das Ziel der Übersichtsarbeit ist, die ökonomischen Auswirkungen von Genexpressionstests in der Therapie des frühen, Hormonrezeptor-positiven, Her2-negativen Mammakarzinoms zur Unterstützung der adjuvanten Therapieentscheidung am Beispiel des Oncotype DX® (ODX) zu erläutern. Im Fokus steht dabei, inwiefern dieser Genexpressionstest zu Kosteneinsparungen führt und ob er als kosteneffektiv bewertet werden kann.

Methodik In gängigen Literaturdatenbanken wurde eine Literaturrecherche zu gesundheitsökonomischen Analysen des ODX durchgeführt. Die Ergebnisse der eingeschlossenen Publikationen wurden ausgewertet und in einem narrativen Review zusammengefasst. Zusätzlich erfolgte eine separate Betrachtung im Kontext des deutschen Gesundheitssystems.

Ergebnisse Es konnten insgesamt 28 Arbeiten identifiziert werden, die sich mit der Wirtschaftlichkeit des ODX auseinandersetzen. Darunter waren 18 Kosten-Effektivitäts-Analysen, 5 Budget-Impact-Analysen sowie 5 Reviews. Die eingeschlossenen Kosten-Effektivitätsanalysen bewerteten den Test insgesamt als kosteneffektiv gegenüber der Regelversorgung, begründet durch ein verbessertes Outcome, eine geringere Anzahl an durchgeführten Chemotherapien, eine geringere Rezidivrate sowie eine höhere Lebenserwartung der Patientinnen. In Abhängigkeit vom jeweiligen Gesundheitssystem wird dem ODX in den Budget-Impact-Analysen ein Einsparpotenzial zugesprochen, teilweise kann es jedoch zu (kurzfristigen) Kostensteigerungen aufgrund der Kosten für die Testung kommen. Die Publikationen zur Wirtschaftlichkeit des ODX im deutschen Versorgungskontext berichten ebenfalls ein Einsparpotenzial.

Schlussfolgerung Die Ergebnisse lassen sich aufgrund unterschiedlicher monetärer Bewertungen zwar nur eingeschränkt auf das deutsche Gesundheitssystem übertragen, es kann dennoch davon ausgegangen werden, dass der Einsatz des ODX auch hier im Längsschnitt zu Kosteneinsparungen führen wird. Eine Erstattung von Genexpressionstests beim frühen Mammakarzinom im Rahmen der Regelversorgung ist demnach unter ökonomischen Gesichtspunkten sinnvoll.
Synthesis and Optoelectronic Properties of Iptycene–Naphthazarin Dyes
Authors: Swager Timothy , Dengiz Cagatay , Wu You-Chi
Published: December 2018

We report the synthesis and characterization of iptycene–naphthazarin dyes by using a sequential Diels–Alder approach. The tautomerization of naphthazarin was used as the key step in the synthesis, with structures confirmed by single-crystal X-ray and NMR analysis. The systematic trends in electronic properties were investigated by UV/Vis spectroscopy. BF2 complexes of the dyes were prepared by reaction with BF3·OEt2 in CH2Cl2.
Synthesis of Substituted Cyclopentenol Derivatives via Intramolecular Addition Reaction of Vinylcopper Species
Authors: Tanino Keiji , Yamaga Hideomi
Published: December 2018

A new method for the synthesis of substituted cyclopentenes is developed, based on an intramolecular 1,2-addition reaction of vinylcopper species generated from 1,1-dibromoalkene derivatives. The substrates are prepared from ketones through the aldol reaction with 3,3-dibromoacrolein followed by silylation of the hydroxyl group. Treatment of the substrate with excess Me2CuLi results in the formation of 3-methyl-2-cyclopenten-1-ol derivatives with good yields.
Deep Plane Facelift: An Evaluation of the High-SMAS versus Standard Incision Points
Authors: Amodeo Chiara , Nabili Vishad , Keller Gregory , Sand Jordan
Published: December 2018

In surgery of the aging face, operative adjustments of the superficial musculoaponeurotic system (SMAS) enhance facial contours. The senior author has observed that the standard deep plane face lift entry points on the SMAS do not provide as much tissue movement in a vertical direction as high-SMAS deep plane face lift entry points. In this study, tissue movement was measured comparing the conventional SMAS entry point with a high-SMAS entry point for deep plane face lifts. Institutional review board approval was obtained. Fourteen facelift patients were enrolled, 10 female and 4 male. Average age was 63.4 (50–81) years. Tissue movement at three points along the jaw line was measured intraoperatively. Standard SMAS entry point suspension resulted in average vertical movements of 6.4, 10.3, and 13.8 mm and average horizontal movements of 3.5, 5.7, and 6.5 mm. High-SMAS entry point resulted in average vertical movements of 11.8, 17.9, and 24.1 mm and average horizontal movements of 5.8, 9.8, and 9.9 mm. This resulted in a 77.3% increase (p = 0.03) in vertical movement and a 61.4% increase (p = 0.02) in horizontal movement with a high-SMAS entry compared with standard SMAS entry. The high-SMAS entry point for a deep plane facelift resulted in a significant increase in lift for both the horizontal and vertical vector on the facial skin flap when compared with the conventional entry.
Thermoelectric properties of Ni0.05Mo3Sb5.4Te1.6 composites with NiSb nanocoating
Authors: Nandihalli Nagaraj , Liang Robert , Wijethunge Dimuthu , Zhou Norman , Kleinke Holger
Published: December 2018

NiSb nanoparticles by 0.034, 0.074 and 0.16 volume fractions were successfully coated on bulk polycrystalline Ni0.05Mo3Sb5.4Te1.6 thermoelectric (TE) particles through a solvothermal route without deteriorating the bulk Ni0.05Mo3Sb5.4Te1.6 material. The samples were consolidated through hot pressing and their thermoelectric (TE) properties were characterized. At 400 K, 500 K, and 600 K, 0.074 NiSb sample exhibited 22%, 16% and 11.3% increases in the power factor (P.F.) compared to bulk material. The main contributing factor to this enhanced power factor is the elevated electrical conductivity. For the same sample, the reciprocal relationship between Seebeck coefficient and electrical conductivity is decoupled. Sample 0.16 NiSb exhibited the highest electrical conductivity among the three samples. The thermal conductivity of the 0.16 sample was less temperature sensitive compared to other samples. HRTEM and SEM tools were applied to comprehend microstructural features and their relationship to TE transport properties. Pore effect on the thermal and electrical conductivity was elucidated. This study shows that grain-boundary manipulation via this wet chemistry technique is indeed an economically viable method to fabricate and optimize the transport properties of bulk TE materials.
Control of magnetic anisotropy in epitaxial Co2MnAl thin films through piezo-voltage-induced strain
Authors: Zhang Bao , Wang Hai-Long , Cao Jin , Li Yu-Cai , Yang Mei-Yin , Xia Ke , Zhao Jian-Hua , Wang Kai-You
Published: December 2018

The voltage-controlled magnetic anisotropy of various magnetic materials is an effective method to realize the electronic devices with low power consumption. Here, we investigated the magnetic properties in Co2MnAl/GaAs heterostructures controlled by piezo voltages-induced strain using the magneto-optical Kerr effect microscopy. The coexistence of the in-plane cubic and uniaxial magnetic anisotropies was observed in the initial state of Co2MnAl thin films. The magnetic anisotropy was manipulated effectively by the piezo voltages. The two-step magnetic hysteresis loop measured along the [1−10] direction was changed into a square loop when the piezo voltage was −30 V (compressed state). On the contrary, the loop of the [110] direction was changed into a two-step loop. The loops of [100] and [010] axes represented the hard axes and were almost unchanged with the piezo voltages. We found that the transformations of loops in [110] and [1−10] axes were manipulated by the piezo voltage induced additional uniaxial anisotropy. Finally, we demonstrated that the planar Hall resistance (RH) in the Hall device can be effectively controlled by the piezo voltages. Our study identified that the voltage controlled room temperature magnetic devices through strain engineering could have great potential for spintronic applications.
Spin Seebeck effect in ɛ-Fe2O3 thin films with high coercive field
Authors: Knížek K. , Pashchenko M. , Levinský P. , Kaman O. , Houdková J. , Jiříček P. , Hejtmánek J. , Soroka M. , Buršík J.
Published: December 2018

We present the experimental observation of the spin Seebeck effect in ε-Fe2−xAlxO3 (x=0 and 0.3) thin films with Pt detection layer. The films with 40–70 nm thicknesses were deposited by a spin-coating method on Y:ZrO2(100) substrates. The prepared films are highly oriented with the easy magnetic a-axis parallel to the film surface. The magnetic hysteresis loops measured for x=0 at room temperature with the magnetic field parallel to the surface exhibit coercive fields up to 11.6 kOe, which is so far the highest value of ε-Fe2O3 thin films. The spin Seebeck signal for x=0 increases proportionally to the film's thickness, which means that the critical thickness corresponding to the magnon propagation length is greater than 70 nm. Al substitution enhances the spin Seebeck signal, while it reduces the coercive field. The shape and coercive field of the spin Seebeck hysteresis loops closely resemble magnetization loops for single phase samples. A difference is encountered in the case of films with a small amount (1–2 vol. %) of secondary soft ferrimagnetic phase, where their presence is revealed in the magnetization loops by a constricted shape, in contrast to the spin Seebeck loops, where no constriction is observed. The large coercive field makes doped ε-Fe2O3 a suitable material for applications of the spin Seebeck effect without an external magnetic field.
Dzyaloshinskii-Moriya interaction at disordered interfaces from ab initio theory: Robustness against intermixing and tunability through dusting
Authors: Zimmermann Bernd , Legrand William , Maccariello Davide , Reyren Nicolas , Cros Vincent , Blügel Stefan , Fert Albert
Published: December 2018

The Dzyaloshinskii-Moriya interaction (DMI), which is essential for the stabilization of topologically non-trivial chiral magnetic textures such as skyrmions, is particularly strong in heterostructures of ultra-thin magnetic materials and heavy elements. We explore by density-functional theory calculations the possibility to modify the magnetic properties at Co/Pt interfaces with chemical disorder. In these systems, we find a particular robustness of the DMI against intermixing. Upon dusting the interface with a third element (all 4d transition metals and B, Cu, Au, and Bi), a strong reduction of the DMI is predicted. This opens up possibilities to tune the DMI through the degrees of intermixing and dusting.
3 μm InAs quantum well lasers at room temperature on InP
Authors: Ji W. Y. , Gu Y. , Zhang J. , Ma Y. J. , Chen X. Y. , Gong Q. , Huang W. G. , Shi Y. H. , He G. X. , Huang H. , Zhang Y. G.
Published: December 2018

An InP-based metamorphic InAs quantum well laser has been demonstrated on an In0.8Al0.2As template with electrically pumped lasing up to 3 μm at room temperature. The dual-layer upper cladding structure, consisting of In0.8Al0.2As first cladding and Al0.35Ga0.65As second cladding layers, is applied to enhance the electronic and optical confinements. Despite the lattice-mismatched approach, X-ray diffraction and photoluminescence measurements show a moderate material quality of the active region. By using 15-nm-thick type-I quantum wells, the lasing wavelength has been achieved to be 3.06 μm in the pulsed mode at 300 K and 2.93 μm in the continuous-wave mode at 220 K.
Molecular adsorption and strain-induced ferromagnetic semiconductor-metal transition in half-hydrogenated germanene
Authors: Wang X. , Liu G. , Liu R. F. , Luo W. W. , Sun B. Z. , Lei X. L. , Ouyang C. Y. , Xu B.
Published: December 2018

Very recently, half-hydrogenated germanene has been achieved in an experiment. In this paper, we investigate the effects of tetracyanoquinodimethane (TCNQ) molecular adsorption and strain on the electronic properties of half-hydrogenated germanene through first-principles. As an electron-acceptor molecule, TCNQ is exploited to non-covalently functionalize the half-hydrogenated germanene. However, this physical adsorption induces a ferromagnetic semiconductor–metal transition in half-hydrogenated germanene due to charge transfer from the substrate to the TCNQ molecule. More importantly, the superstructure of half-hydrogenated germanene/TCNQ is extremely sensitive to biaxial tensile strain. Under the biaxial tensile strain of 0.25%, the ferromagnetic semiconductor–metal transition induced by molecular adsorption can surprisingly be overturned. Meanwhile, a strong p-type doping is exhibited. Remarkably, it would return from a ferromagnetic semiconductor to a metal again when the biaxial tensile strain increases to 1.5%. Our analysis based on the structural and electronic properties of half-hydrogenated germanene/TCNQ indicates that such metal–semiconductor–metal transition in half-hydrogenated germanene/TCNQ under biaxial tensile strain may originate from the strong local deformation, resulting in the energy of the valence band maximum decreasing below or increasing above the Fermi level.
Investigation of the performance of strain-engineered silicon nanowire field effect transistors (ɛ-Si-NWFET) on IOS substrates
Authors: Chatterjee Sulagna , Sikdar Subhrajit , Nag Chowdhury Basudev , Chattopadhyay Sanatan
Published: December 2018

In the current work, a design space for developing the performance enhanced strain-engineered Si nanowire field-effect-transistors has been provided. The fraction of insertion of the nanowire channel into the Insulator-on-Silicon substrate with judicious selection of high-k gate insulators is used as the key design parameter. The combined effect of fractional insertion and gate insulators results in inducing stress into the nanowire channel and, depending on their selection, it changes from tensile to compressive. Such induced-stress alters the existing inherent phononic-stress, leading to the modification of the carrier transport in the device channel. The carrier transport behavior in such partially embedded nanowire FETs has been modeled by incorporating the relevant stress-related effects into the indigenously developed self-consistent quantum-electrostatic framework. These equations are solved by employing the non-equilibrium Green's function formalism. The study shows the phonon scattering under tensile strain to occur at the expense of electron energy; however, the electrons can also gain energy during such scattering in compressive stress. Thus, the device current has been observed to increase with tensile stress and it achieves relatively smaller values when the inherent tensile phononic stress is balanced by the induced compressive stress. However, the current is finally observed to increase once the compressive stress overcomes the inherent tensile phononic stress. In general, the present devices exhibit promising Ion/Ioff ratio for all of the fractional insertions and gate dielectrics with a maximum Ioff of <10 nA/μm, threshold voltage of sub-0.3 V, gm of ∼104 µS/µm, sub-threshold swing of ∼100 mV/dec, and drain-induced-barrier-lowering of ∼100 mV/V.
Stochastic unfolding of nanoconfined DNA: Experiments, model and Bayesian analysis
Authors: Krog Jens , Alizadehheidari Mohammadreza , Werner Erik , Bikkarolla Santosh Kumar , Tegenfeldt Jonas O. , Mehlig Bernhard , Lomholt Michael A. , Westerlund Fredrik , Ambjörnsson Tobias
Published: December 2018

Nanochannels provide a means for detailed experiments on the effect of confinement on biomacromolecules, such as DNA. Here we introduce a model for the complete unfolding of DNA from the circular to linear configuration. Two main ingredients are the entropic unfolding force and the friction coefficient for the unfolding process, and we describe the associated dynamics by a non-linear Langevin equation. By analyzing experimental data where DNA molecules are photo-cut and unfolded inside a nanochannel, our model allows us to extract values for the unfolding force as well as the friction coefficient for the first time. In order to extract numerical values for these physical quantities, we employ a recently introduced Bayesian inference framework. We find that the determined unfolding force is in agreement with estimates from a simple Flory-type argument. The estimated friction coefficient is in agreement with theoretical estimates for motion of a cylinder in a channel. We further validate the estimated friction constant by extracting this parameter from DNA’s center-of-mass motion before and after unfolding, yielding decent agreement. We provide publically available software for performing the required image and Bayesian analysis.
High performance InGaN double channel high electron mobility transistors with strong coupling effect between the channels
Authors: Zhang Yachao , Wang ZhiZhe , Guo Rui , Liu Ge , Xu Shengrui , Bao Weimin , Zhang Jincheng , Hao Yue
Published: December 2018

In this paper, high performance InGaN double channel (DC) high electron mobility transistors (HEMTs) are proposed and systematically investigated. Due to the coordination of double InGaN channels, a large maximum drain current density and a distinct double-hump feature of the transconductance and frequency performance are achieved. More importantly, it is revealed that the coupling effect between the two InGaN channels is much stronger than that of the conventional GaN DC HEMTs. This characteristic leads to a remarkable enhancement in the gate voltage swing, indicating the excellent linearity of the InGaN DC HEMTs at both dc and rf conditions. Benefiting from the enhanced electron confinement in InGaN channels, the fabricated HEMTs show a low off state drain leakage current of 0.26 μA/mm and a high on/off current ratio (Ion/Ioff) of 5.1 × 106. In addition, the desirable current collapse and breakdown characteristics are also obtained. This work convincingly demonstrates the great potential and practicality of the InGaN DC HEMTs for high power and high bandwidth applications.
Depth sensitive imaging of graphene with an atomic resolution microscope
Authors: Morishita Shigeyuki , Senga Ryosuke , Lin Yung-Chang , Kato Ryuichi , Sawada Hidetaka , Suenaga Kazutomo
Published: December 2018

The three-dimensional information of atomic positions is required to determine the atomic structure of materials. However, images obtained using high-resolution transmission electron microscopes are generally two-dimensional projections of three-dimensional structures. The depth resolution of general microscopes is still on the order of nanometers, and a smaller depth of field is required to realize atomic depth-resolution imaging. Here, we propose highly depth-sensitive imaging using a low-voltage atomic-resolution transmission electron microscope equipped with a higher order geometrical aberration corrector and a monochromator. A long wavelength of low energy electrons and a large acceptance angle of the microscope allow for a shallow depth of field and atomic-level depth sensitivity. We demonstrate that the depth resolution and depth precision can allow for ångström and sub-ångström levels, respectively. Applying this highly depth-sensitive microscope, the depth deviation of monolayer graphene with dislocations is detected as the difference of defocus. The buckling structures of dislocation dipole and tripole are directly observed using a single image. Combining the proposed depth-sensitive microscope with through-focal imaging will allow for the analysis of various low-dimensional materials in three dimensions with atomic depth resolution.
The effects of curvature on the thermal conduction of bent silicon nanowire
Authors: Liu Xiangjun , Zhou Hangbo , Zhang Gang , Zhang Yong-Wei
Published: December 2018

Curvature induced by mechanical deformation in nanostructures has been found to significantly affect their stability and reliability during applications. In this work, we investigated the effects of curvature induced by mechanical bending on the thermal properties of silicon nanowire (SiNW) by using molecular dynamics simulations. By examining the relationship between the curved geometry and local temperature/heat flux distribution, we found that there is no temperature gradient/heat flux along the radial direction of the bent SiNW, and the local heat current density along the circumferential direction varies with the radius of curvature. Interestingly, a ∼10% reduction in the thermal conductivity is found in the bent SiNW due to the depression of long-wavelength phonons caused by its inhomogeneous deformation. The present work demonstrates that the curvature induced by mechanical bending can be used to modulate the thermal conductivity of SiNWs.
Electrical tuning of metal-insulator-metal metasurface with electro-optic polymer
Authors: Zhang Jiaqi , Kosugi Yuji , Otomo Akira , Ho Ya-Lun , Delaunay Jean-Jacques , Nakano Yoshiaki , Tanemura Takuo
Published: December 2018

Electrically tunable active metasurfaces are attracting great interest as a possible means to realize two-dimensional pixelated surface-normal modulators for wide applications, such as high-speed imaging, optical interconnects, and photonic switching. In this work, we fabricate a metallic metasurface embedded with an electro-optic (EO) polymer and experimentally demonstrate the electrical tuning of its reflectance property. Unlike the previously demonstrated surface-normal modulators based on the EO polymer, we utilize the Fabry-Perot resonance of a metal-insulator-metal mode to trap the incident light inside a thin EO polymer layer to enhance the modulation efficiency. By applying voltage between the top and bottom layers of Au, we observe a clear spectral shift in the plasmonic resonance as well as a 5-MHz dynamic modulation at 1630-nm wavelength.
Distinctive features of the high-current glow discharge with the hollow cathode at low gas pressures
Authors: Metel A. , Melnik Yu.
Published: December 2018

A pulsed hollow cathode glow discharge with current up to 200 A, with the pulse width amounting to a few milliseconds, is studied in a wide range of the gas pressure p from 0.01 to 10 Pa. The high current discharge is established due to the application of a high-voltage pulse with amplitude Uo up to 5 kV between the anode and the hollow cathode of a continuous discharge with a current of Io = 0.5 A. The establishing time τ ranges from 10 to 300 μs, diminishes with the pulse amplitude growth, increases in the gas pressure, and decreases in the output orifice area of the hollow cathode. At Uo > 2.5 kV, an abnormal mode of the discharge establishing process is observed with intensive oscillations of the discharge current and voltage in the frequency range from 1 to 10 MHz. In the abnormal mode, the high current establishing time τ can be reduced by hundred times down to τ ∼ 1 μs. At a low gas pressure p < 0.1 Pa, the high current can be reached only in the abnormal mode. Without oscillations at the pulse front, only low-current high-voltage discharge is established.
Miniaturized high-frequency sine wave gating InGaAs/InP single-photon detector
Authors: Jiang Wen-Hao , Gao Xin-Jiang , Fang Yu-Qiang , Liu Jian-Hong , Zhou Yong , Jiang Li-Qun , Chen Wei , Jin Ge , Zhang Jun , Pan Jian-Wei
Published: December 2018

High-frequency gating InGaAs/InP single-photon detectors (SPDs) are widely used for applications requiring single-photon detection in the near-infrared region such as quantum key distribution. Reducing SPD size is highly desired for practical use, which is favorable to the implementation of further system integration. Here we present, to the best of our knowledge, the most compact high-frequency sine wave gating (SWG) InGaAs/InP SPD. We design and fabricate an InGaAs/InP single-photon avalanche diode (SPAD) with optimized semiconductor structure and then encapsulate the SPAD chip and a mini-thermoelectric cooler inside a butterfly package with a size of 12.5 mm × 22 mm × 10 mm. Moreover, we implement a monolithic readout circuit for the SWG SPD in order to replace the quenching electronics that is previously designed with board-level integration. Finally, the components of SPAD, the monolithic readout circuit, and the affiliated circuits are integrated into a single module with a size of 13 cm × 8 cm × 4 cm. Compared with the 1.25 GHz SWG InGaAs/InP SPD module (25 cm × 10 cm × 33 cm) designed in 2012, the volume of our miniaturized SPD is reduced by 95%. After the characterization, the SPD exhibits excellent performance with a photon detection efficiency of 30%, a dark count rate of 2.0 kcps, and an afterpulse probability of 8.8% under the conditions of 1.25 GHz gating rate, 100 ns hold-off time, and 243 K. Also, we perform the stability test over one week, and the results show the high reliability of the miniaturized SPD module.
Modeling the effects of aluminum and ammonium perchlorate addition on the detonation of the high explosives C4H8O8N8 (HMX) and C3H6O6N6 (RDX)
Authors: Baek Donghyeon , Kim Bohoon , Yoh Jack J.
Published: December 2018

Metalized high explosives effectively tailor the explosion impulse at lowered detonation pressures of common high performance explosives such as C3H6O6N6 (RDX) and C4H8O8N8 (HMX). The presence of aluminum (Al) with and without ammonium perchlorate (AP) allows the subsequent burning for longer and sustained reactions of enhanced blast explosives. The modeling of reaction rate laws for three explosives with varied amounts of Al, AP, RDX, and HMX is reported. The model validation included the rate stick test for understanding the explosive reaction of the three samples and the large-scale gap test for determining their ignition sensitivity. The experimental results confirmed the accuracy of the model in simulating the shock sensitivity and the size effects before detonation failure. The effect of enhanced blast of these explosives in the presence of Al and AP is also reported.
Prediction of two-dimensional organic topological insulator in metal-DCB lattices
Authors: Hsu Chia-Hsiu , Huang Zhi-Quan , Macam Gennevieve M. , Chuang Feng-Chuan , Huang Li
Published: December 2018

Based on first-principles calculations, we systematically investigated a two-dimensional (2D) organometallic framework consisting of metal atoms (elements from groups IIIA, IVA, VA, VIA, IB, and Pt) and dicyanobenzenes (DCBs). Our stability analysis showed that the system prefers the buckled structure in metals with p-orbital valence electrons, whereas in metals with d-orbitals, the planar phase is preferable. Topological invariants (Z2) of these systems were calculated, and they are identified as 2D intrinsic organic topological insulators. Au- and Bi-DCB are exemplar materials with the largest bandgaps within IB and VA groups. Moreover, Au-DCB exhibits robustness of its topological phase against strain. Furthermore, the topologically protected edge states in Au-DCB are identified to further verify the Z2 invariant. Interestingly, utilizing hole doping in Bi-DCB leads to a nearly flat Chern band and results in the quantum anomalous Hall phase. Our results suggest that these organometallic frameworks are promising for potential applications in quantum spintronics with the merits of low cost and ease of synthesis.
Solution of the time dependent Schrödinger equation leading to Fowler-Nordheim field emission
Authors: Costin Ovidiu , Costin Rodica , Jauslin Ian , Lebowitz Joel L.
Published: December 2018

We solve the time-dependent Schrödinger equation describing the emission of electrons from a metal surface by an external electric field E, turned on at t=0. Starting with a wave function ψ(x,0), representing a generalized eigenfunction when E=0, we find ψ(x,t) and show that it approaches, as t→∞, the Fowler-Nordheim tunneling wavefunction ψE. The deviation of ψ from ψE decays asymptotically as a power law t−32. The time scales involved for typical metals and fields of several V/nm are of the order of femtoseconds. We plot the short-time evolution of the current and density.
Regulation of steroidogenic function of luteal cells by thrombospondin and insulin in water buffalo (Bubalus bubalis)
Authors: Paul Avishek , Punetha Meeti , Kumar Sai , Sonwane Arvind , Chouhan Vikrant S. , Singh Gyanendra , Maurya V. P. , Sarkar M.
Published: December 2018

The present study examined the effect of exogenous thrombospondin 1 (TSP1) on the steroidogenic function of luteal cells cultured invitro. Furthermore, the transcriptional interaction of insulin with TSP1 and its receptor, cluster of differentiation 36 (CD36) were also investigated. At the highest dose (500ngmL−1) TSP1 significantly downregulated the expression of the angiogenic marker von Willebrand factor (vWF) and progesterone production in cultured luteal cells. Moreover, the simultaneous upregulation in the expression of caspase 3 by exogenous TSP1 was consistent with a reduction in the number of viable luteal cells as determined by 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltertrazolium bromide (MTT) assay after 72h of culture. However, the expression of critical enzymes in the progesterone synthetic pathway was not significantly modulated by treatment with TSP1 in cultured luteal cells. Knocking out of endogenous TSP1 with the clustered regularly interspaced short palindromic repeats (CRISPR)/ CRISPRassociated protein9 (Cas9) system improved the viability of luteal cells as well as increasing progesterone production and decreasing caspase 3 activation. Insulin treatment suppressed the expression of TSP1 and CD36 in cultured luteal cells in a dose- and time-dependent manner. To conclude, TSP1 acts as a negative endogenous regulator of angiogenesis that attenuates progesterone production, possibly by reducing the number of luteal cells via apoptosis during luteal regression, whereas insulin as a luteinising signal may have inhibited the thrombospondin system for the efficient development of luteal function.
Variations in pest bird density in Argentinean agroecosystems in relation to land use and/or cover, vegetation productivity and climate
Authors: Calamari Noelia C. , Canavelli Sonia B. , Cerezo Alexis , Dardanelli Sebastián , Bernardos Jaime N. , Zaccagnini María E.
Published: December 2018

Context Changes in environmental conditions may influence bird populations, including pest bird species, and their distribution. In Argentina, particularly in the Pampas region, agricultural expansion has resulted in important changes in agroecosystems, with impacts on bird species. Aims This study analysed the relationship between pest bird densities and the environmental variables associated with land use and/or cover, vegetation productivity and climate. The study focused on the most important pest bird species to grain crops in Argentina and Uruguay: the eared dove (Zenaida auriculata) and the monk parakeet (Myiopsitta monachus). Methods An area in Central Argentina was divided into three agro-productive regions, one predominantly agricultural and two with mixed production activities: agricultural rangeland and agricultural forested rangeland. Bird populations were sampled on a yearly basis between 2003 and 2011 in point-transects located along secondary roads (47 routes in total). Linear mixed models and a multi-model inference approach were used to compare the effects of individual predictive variables on bird densities. Key results Mean estimated density for the eared dove was 0.39 individuals per ha (±0.02), almost three times the density of the monk parakeet (0.10 individuals per ha±0.02). The spatial distribution of changes in density of the eared dove and monk parakeet showed irregular patterns across the study area. Density of eared dove was directly related to cover of native and exotic woodlots and inversely related to cover of fallow and weedy fields, and to temperature and rainfall. Monk parakeet density, in turn, was directly related to cover of woodlots. Conclusions The density of eared doves and monk parakeets changed mostly in relation to land use and/or cover and, to a lesser extent, to climatic conditions. Information of pest bird populations in a long-term period allowed us to understand spatial patterns in bird population distribution and to identify the main environmental factors explaining them. Implications The consideration of land use and/or cover, vegetation productivity and climate variables at regional scale, measured during a long-term period, would be critical for anticipating population increases and, possibly, increases in crop damage.
GABA release selectively regulates synapse development at distinct inputs on direction-selective retinal ganglion cells
Authors: Bleckert Adam , Zhang Chi , Turner Maxwell H. , Koren David , Berson David M. , Park Silvia J. H. , Demb Jonathan B. , Rieke Fred , Wei Wei , Wong Rachel O.
Published: December 2018

Significance

Output characteristics of a neuron are shaped by synaptic inhibition onto its soma and dendrites. These subcellular compartments of direction-selective retinal ganglion cells (DSGCs) receive input from different types of inhibitory neurons, and only dendritic inhibition generates the DSGC’s direction selectivity. Perturbing γ-aminobutyric acid (GABA) release either at all or at selected GABAergic inputs uncovered differential roles for GABAergic transmission on synaptic development at the DSGC’s soma and dendrites. Although dendritic GABA
A
receptor clustering is largely invariant to transmission loss, somatic receptor clusters can increase in number and size. These findings advance our understanding of the roles of activity-dependent and -independent mechanisms in the development of inhibitory inputs that play separate roles in controlling the output of an individual neuron.
Predicting plant conservation priorities on a global scale
Authors: Pelletier Tara A. , Carstens Bryan C. , Tank David C. , Sullivan Jack , Espíndola Anahí
Published: December 2018

The conservation status of most plant species is currently unknown, despite the fundamental role of plants in ecosystem health. To facilitate the costly process of conservation assessment, we developed a predictive protocol using a machine-learning approach to predict conservation status of over 150,000 land plant species. Our study uses open-source geographic, environmental, and morphological trait data, making this the largest assessment of conservation risk to date and the only global assessment for plants. Our results indicate that a large number of unassessed species are likely at risk and identify several geographic regions with the highest need of conservation efforts, many of which are not currently recognized as regions of global concern. By providing conservation-relevant predictions at multiple spatial and taxonomic scales, predictive frameworks such as the one developed here fill a pressing need for biodiversity science.