bluuebunny/crossref_metadata_2025 huggingface dataset:
The bifurcation of periodic orbits and equilibrium points in the linked restricted three-body problem with parameter ω
Authors: Liang Yuying , Shan Jinjun , Xu Ming , Lin Mingpei
Published: October 2019

This paper is devoted to the bifurcation of periodic orbits and libration points in the linked restricted three-body problem (LR3BP). Inherited from the classic circular restricted three-body problem (CR3BP), it retains most of the dynamical structure of CR3BP, while its dynamical flow is dominated by angular velocity ω and Jacobi energy C. Thus, for the first time, the influence of the angular velocity in the three-body problem is discussed in this paper based on ω-motivated and C-motivated bifurcation. The existence and collision of equilibrium points in the LR3BP are investigated analytically. The dynamic bifurcation of the LR3BP under angular velocity variation is obtained based on three typical kinds of periodic orbits, i.e., planar and vertical Lyapunov orbits and Halo orbits. More bifurcation points are supplemented to Doedel's results in the CR3BP for a global sketch of bifurcation families. For the first time, a new bifurcation phenomenon is discovered that as ω approaches to 1.4, two period-doubling bifurcation points along the Halo family merge together. It suggests that the number and the topological type of bifurcation points themselves can be altered when the system parameter varies in LR3BP. Thus, it is named as “bifurcation of bifurcation” or “secondary bifurcation” in this paper. At selected values of ω, the phase space structures of equilibrium points L2 and L3 are revealed by Lie series method numerically, presenting the center manifolds on the Poincaré section and detecting three patterns of evolution for center manifolds in LR3BP.
Influences of experimental parameters on characteristics of focusing through scattering media by wavefront shaping
Authors: Yang Yang , Tan Wenjiang , Si Jinhai , Li Jing , Tang Shiyun
Published: October 2019

The feedback-based wavefront shaping method can be used to focus light behind or inside strongly scattering media. In this study, we investigated several characteristics of the focus after optimization to evaluate the enhancement effect of the wavefront shaping method, including the spot size, the intensity, and two types of enhancement factor. In addition, we studied the influences of various experimental parameters on these characteristics, including the number of controlled segments N, diameter of the irradiated area at the front of the scattering medium D, and distance between the expected focusing spot and scattering medium Z. A larger N and smaller Z provided a smaller focus spot. For a brighter focus spot, a larger N and smaller D and Z were required, while for a high-resolution focus spot, larger N, D, and Z were required.
High resolution energy-time of flight spectrometer: Dehydrogenation of fluorene cation as case study
Authors: Vinitha M. V. , Kala A. , Kumar S. , Kadhane U. R.
Published: October 2019

Testing and performance validation of a new multipurpose time-of-flight mass spectrometer followed by an energy analyzer is presented. The instrument with high mass and energy resolution is primarily designed to study cations of polycyclic aromatic hydrocarbons (PAHs) and their dehydrogenation process. The energy correlated time-of-flight measurement is supplemented by Monte Carlo simulation to probe the dehydrogenation process in a relatively small PAH cation. The experiment is carried out on fluorene+ on a timescale of several microseconds. Fluorene cations with high internal energies were produced using UV multiphoton ionization. Specific n-photon processes leading to ionization as well as H-loss reaction were identified. The average value of dehydrogenation rate is estimated by fitting the measured data to the outcome of simulations. The quantification of H loss decay rate is in agreement with previously reported decay rate measurement. This corresponds to the internal energy available by inner valence electron emission caused by three photon process. The effectiveness of the instrument to access a range of decay rates (103–107 s−1) in a single measurement is demonstrated.
Importance of interfacial crystallinity to reduce open-circuit voltage loss in organic solar cells
Authors: Izawa Seiichiro , Shintaku Naoto , Kikuchi Mitsuru , Hiramoto Masahiro
Published: October 2019

Reducing the energy loss in output voltage is critically important for further enhancing the efficiency of organic solar cells (OSCs). Here, we report that OSCs with high mobility and highly crystalline donor (D) and acceptor (A) materials were able to reduce an open-circuit voltage (VOC) loss. The crystallinity of the acceptor layer could be altered by appropriate selection of the three molecules with different alkyl side chain lengths. The VOC was found to increase as the crystallinity of the acceptor layer increased. The origin of the high VOC was that the highly crystalline D/A interface reduced the energy loss in the output voltage by realizing ideal band-to-band recombination. Especially, the high crystallinity of the several molecular layers (less than 6 nm) in the vicinity of the D/A interface was important for realizing the high VOC. Our results demonstrate that the careful design of the D/A interface enables high power conversion efficiencies to be achieved in OSCs by reducing open-circuit voltage loss.
Toward CMOS like devices from two-dimensional channel materials
Authors: Wu Peng , Appenzeller Joerg
Published: October 2019

This research update explains in detail the critical aspects of Schottky barrier (SB) field-effect transistors (FETs) for circuit implementations. In particular, it focuses on two-dimensional (2D) channel materials such as black phosphorus. After an initial tutorial about the operation of SB-FETs, this article discusses various scaling approaches and how proper unipolar device characteristics from 2D layered materials can be obtained. Various transistor layouts described in the literature are evaluated in terms of the achieved device performance specs, and the most advanced experimental approach is presented that combines proper scaling, source/drain work function engineering, and gating. This article closes by highlighting the performance of an inverter obtained from properly designed BP-based n-type and p-type transistors.
Spatio-temporal numerical modeling of reaction-diffusion measles epidemic system
Authors: Ahmed Nauman , Wei Zhouchao , Baleanu Dumitru , Rafiq M. , Rehman M. A.
Published: October 2019

In this work, we investigate the numerical solution of the susceptible exposed infected and recovered measles epidemic model. We also evaluate the numerical stability and the bifurcation value of the transmission parameter from susceptibility to a disease of the proposed epidemic model. The proposed method is a chaos free finite difference scheme, which also preserves the positivity of the solution of the given epidemic model.
Thermoelectric transport trends in group 4 half-Heusler alloys
Authors: Berland Kristian , Shulumba Nina , Hellman Olle , Persson Clas , Løvvik Ole Martin
Published: October 2019

The thermoelectric properties of 54 different group 4 half-Heusler (HH) alloys have been studied from first principles. Electronic transport was studied with density functional theory using hybrid functionals facilitated by the k⋅p method, while the temperature-dependent effective potential method was used for the phonon contributions to the figure of merit ZT. The phonon thermal conductivity was calculated including anharmonic phonon-phonon, isotope, alloy, and grain-boundary scattering. HH alloys have an XYZ composition, and those studied here are in the group 4-9-15 (Ti,Zr,Hf)(Co,Rh,Ir)(As,Sb,Bi) and group 4-10-14 (Ti,Zr,Hf)(Ni,Pd,Pt)(Ge,Sn,Pb). The electronic part of the thermal conductivity was found to significantly impact ZT and thus the optimal doping level. Furthermore, the choice of functional was found to significantly affect thermoelectric properties, particularly for structures exhibiting band alignment features. The intrinsic thermal conductivity was significantly reduced when alloy and grain-boundary scattering were accounted for, which also reduced the spread in thermal conductivity. It was found that sublattice disorder on the Z-site, i.e., the site occupied by group 14 or 15 elements, was more effective than X-site substitution, occupied by group 4 elements. The calculations confirmed that ZrNiSn, ZrCoSb, and ZrCoBi based alloys display promising thermoelectric properties. A few other n-type and p-type compounds were also predicted to be potentially excellent thermoelectric materials, given that sufficiently high charge carrier concentrations can be achieved. This study provides insight into the thermoelectric potential of HH alloys and casts light on strategies to optimize the thermoelectric performance of multicomponent alloys.
Steering a solute between coexisting solvation states: Revisiting nonequilibrium work relations and the calculation of free energy differences
Authors: Heidari Maziar , Cortes-Huerto Robinson , Potestio Raffaello , Kremer Kurt
Published: October 2019

By analogy with single-molecule pulling experiments, we present a computational framework to obtain free energy differences between complex solvation states. To illustrate our approach, we focus on the calculation of solvation free energies (SFEs). However, the method can be readily extended to cases involving more complex solutes and solvation conditions as well as to the calculation of binding free energies. The main idea is to drag the solute across the simulation box where atomistic and ideal gas representations of the solvent coexist at constant temperature and chemical potential. At finite pulling speeds, the resulting work allows one to extract SFEs via nonequilibrium relations, whereas at infinitely slow pulling speeds, this process becomes equivalent to the thermodynamic integration method. Results for small molecules well agree with literature data and pave the way to systematic studies of arbitrarily large and complex molecules.
Visible-light-mediated carrier type modulation at the LaAlO3/SrTiO3 interface
Authors: Su Siyu , Gao Haobin , Shen Yifan , Peng Wei , Zhu Xiaohong
Published: October 2019

A LaAlO3/SrTiO3 (LAO/STO) heterointerface with the sheet charge density of electrons on the order of magnitude of 1013 e/cm2 was obtained by depositing a 10 unit-cell LAO layer on the TiO2-teminated STO substrate. An obvious persistent photoconductivity effect was observed for the as-prepared LAO/STO heterointerface. By way of Hall-like coefficient and magnetoresistance measurements at different light power intensities, it is demonstrated that the mechanism of magnetoresistance changes with the increase in light power density on the sample; more importantly, when the light power intensity is increased to a specific value, 270 mW in this case, the carrier type of the interface is tailored from n-type to p-type, which is probably ascribed to the photoinduced p-type hole dopants and has never been reported at the LAO/STO interface before, thus providing important insights into a controllable heterointerface for oxide-based thin film electronics.
Continuous wave operation of InAs-based quantum cascade lasers at 20
μ
m
Authors: Loghmari Z. , Bahriz M. , Meguekam A. , Nguyen Van H. , Teissier R. , Baranov A. N.
Published: October 2019

We report low threshold continuous wave (CW) operation of InAs/AlSb quantum cascade lasers emitting around 20 μm. The laser cavity was made of a plasmon-enhanced dielectric waveguide with cladding layers made of n-InAs. The devices exhibited a threshold current density of 1.38 kA/cm2 at the maximum temperature of CW operation of 240 K and an output power of 14 mW/facet at T = 80 K. In pulsed mode, the lasers operated up to 380 K with a threshold current density of 1.15 kA/cm2 at room temperature.
Silicon nanocrystals-based electroluminescent resistive switching device
Authors: Frieiro J. L. , López-Vidrier J. , Blázquez O. , Yazıcıoğlu D. , Gutsch S. , Valenta J. , Hernández S. , Zacharias M. , Garrido B.
Published: October 2019

In the last few years, the emergence of studies concerning the resistive switching (RS) phenomenon has resulted in the finding of a large amount of materials being capable of acting as an active layer in such devices, i.e., the layer where the change in resistance takes place. Whereas the normal operation consists of the electrical readout of the modified resistance state of the device after electrical writing, electro-photonic approaches seek the involvement of light in these devices, be it either for the active Set or Reset operations or the readout. We propose in this work silicon nanocrystal multilayers (Si NC MLs) as an active material for being used in RS devices, taking advantage of their outstanding optical properties. The resistance states of Si NC MLs were obtained by electrical excitation, whose readout is carried out by electrical and electro-optical means, thanks to a distinguishable electroluminescence emission under each state. To achieve this, we report on an adequate design that combines both the Si NC MLs with ZnO as a transparent conductive oxide, whose material properties ensure the device RS performance while allowing the electro-optical characterization. Overall, such an occurrence states the demonstration of a Si NCs-based electroluminescent RS device, which paves the way for their future integration into photonic integrated circuits.
Silicon photonic wavelength cross-connect with integrated MEMS switching
Authors: Seok Tae Joon , Luo Jianheng , Huang Zhilei , Kwon Kyungmok , Henriksson Johannes , Jacobs John , Ochikubo Lane , Muller Richard S. , Wu Ming C.
Published: October 2019

We report on monolithically integrated wavelength cross-connects (WXCs) on an enhanced silicon photonic platform with integrated micro-electro-mechanical-system (MEMS) actuators. An 8 × 8 WXC with 8 wavelength channels comprising 16 echelle gratings and 512 silicon photonic MEMS switches is integrated on a 9.7 mm × 6.7 mm silicon chip. The WXC inherits the fundamental advantages of silicon photonic MEMS space switches, including low loss, broad optical bandwidth, large fabrication tolerance, and simple digital control. The WXC exhibits a low crosstalk of −30 dB, a submicrosecond switching time of 0.7 µs, and on-chip optical insertion losses varying from 8.8 dB to 16.4 dB. To our knowledge, it is the largest channel capacity (64 channels = 8 ports × 8 wavelengths) integrated WXC ever reported.
Dynamical systems approach to study thermoacoustic transitions in a liquid rocket combustor
Authors: Kasthuri Praveen , Pavithran Induja , Pawar Samadhan A. , Sujith R. I. , Gejji Rohan , Anderson William
Published: October 2019

Liquid rockets are prone to large amplitude oscillations, commonly referred to as thermoacoustic instability. This phenomenon causes unavoidable developmental setbacks and poses a stern challenge to accomplish the mission objectives. Thermoacoustic instability arises due to the nonlinear interaction between the acoustic and the reactive flow subsystems in the combustion chamber. In this paper, we adopt tools from dynamical systems and complex systems theory to understand the dynamical transitions from a state of stable operation to thermoacoustic instability in a self-excited model multielement liquid rocket combustor based on an oxidizer rich staged combustion cycle. We observe that this transition to thermoacoustic instability occurs through a sequence of bursts of large amplitude periodic oscillations. Furthermore, we show that the acoustic pressure oscillations in the combustor pertain to different dynamical states. In contrast to a simple limit cycle oscillation, we show that the system dynamics switches between period-3 and period-4 oscillations during the state of thermoacoustic instability. We show several measures based on recurrence quantification analysis and multifractal theory, which can diagnose the dynamical transitions occurring in the system. We find that these measures are more robust than the existing measures in distinguishing the dynamical state of a rocket engine. Furthermore, these measures can be used to validate models and computational fluid dynamics simulations, aiming to characterize the performance and stability of rockets.
Brain-on-a-chip: A history of development and future perspective
Authors: Bang Seokyoung , Jeong Sohyeon , Choi Nakwon , Kim Hong Nam
Published: October 2019

Since the advent of organ-on-a-chip, many researchers have tried to mimic the physiology of human tissue on an engineered platform. In the case of brain tissue, structural connections and cell–cell interactions are important factors for brain function. The recent development of brain-on-a-chip is an effort to mimic those structural and functional aspects of brain tissue within a miniaturized engineered platform. From this perspective, we provide an overview of trace of brain-on-a-chip development, especially in terms of complexity and high-content/high-throughput screening capabilities, and future perspectives on more in vivo-like brain-on-a-chip development.
Robust and optimal sparse regression for nonlinear PDE models
Authors: Gurevich Daniel R. , Reinbold Patrick A. K. , Grigoriev Roman O.
Published: October 2019

This paper investigates how models of spatiotemporal dynamics in the form of nonlinear partial differential equations can be identified directly from noisy data using a combination of sparse regression and weak formulation. Using the 4th-order Kuramoto-Sivashinsky equation for illustration, we show how this approach can be optimized in the limits of low and high noise, achieving accuracy that is orders of magnitude better than what existing techniques allow. In particular, we derive the scaling relation between the accuracy of the model, the parameters of the weak formulation, and the properties of the data, such as its spatial and temporal resolution and the level of noise.
Investigation on the impact of hydrogen on the passivation of silicon surface states in clean and copper contaminated conditions
Authors: Song Lihui , Yang Deren , Yu Xuegong
Published: October 2019

Hydrogen is identified as a useful technique to passivate defects within crystalline silicon. However, the effect of hydrogen passivation for a silicon surface is normally characterized as a reduction in surface recombination velocity (SRV), which is not enough to reflect the detailed changes of electronic properties, such as defect density, defect energy levels, and capture cross section, of silicon surface states. In this paper, we utilized the transient capacitance measurement to characterize the detailed electronic properties of silicon surface states before and after hydrogenation. The differences, in terms of the effects of hydrogenation on silicon surface states, either in copper contaminated conditions or clean conditions, are presented and discussed.
Multiple selective absorption peaks of acoustic waves in a one-dimensional composite
Authors: Wang Zhenyu , Yang Hai , Zhao Degang , Wang Rongli , Jin Guojun
Published: October 2019

We investigate a one-dimensional composite with a very low loss coefficient and find that multiple selective absorption peaks reach close to 100% absorption of incident acoustic waves when the acoustic waves propagate through this system. Especially, the unidirectional absorption is demonstrated when the propagation direction of acoustic waves is reversed. These high absorptions stem from the excitations of the strong resonances, which depend on not only the low loss in this composite but also the huge impedance mismatch at the outgoing interface. To further investigate those selective absorption, we construct an equivalent structural model, and our calculations show that these absorption peaks have the extraordinary response to the imaginary part of the effective mass density and bulk modulus. The results exhibit that the imaginary part of the effective mass density and bulk modulus at the frequencies of the absorption peaks abruptly appear, in the meanwhile the real part of those become zero. Based on these theoretical results, an unidirectional absorption device with multiple selection of frequencies can be designed.
High performance nBn detectors based on InGaAsSb bulk materials for short wavelength infrared detection
Authors: Li Nong , Sun Ju , Jia Qingxuan , Song Yifeng , Jiang Dongwei , Wang Guowei , Xu Yingqiang , Niu Zhichuan
Published: October 2019

We report a low dark current, high quantum efficiency nBn photodetectors based on In0.28Ga0.72As0.25Sb0.75 bulk materials with a cut-off wavelength of 3μm at room temperature. Generation-Recombination current was suppressed using an nBn design to shift deplete region from In0.28Ga0.72As0.25Sb0.75 active region into a wide band gap AlGaSb barrier region. The Arrhenius plots of R0A-1/T show that there is no Generation-Recombination current detected in nBn device, whereas pin devices have a Generation-Recombination dominant dark current at temperatures ranging from 160K to 220K. Optical characterizations at 300K show the nBn device using InGaAsSb as an absorption material has a relative high quantum efficiency. The nBn device exhibits a peak specific detectivity of 4.8×1010 Jones under 200mV reverse bias voltage at 300K. The low dark current, high quantum efficiency and band gap tunability are expected to make InGaAsSb bulk material a competitive candidate for short wavelength infrared regime.
Exciton-optical phonon coupling in II-VI semiconductor nanocrystals
Authors: Kelley Anne Myers
Published: October 2019

This perspective reviews the topic of exciton-phonon coupling (EPC) in II-VI semiconductor nanocrystals. First, EPC is defined and its relevance is discussed, both as it influences the properties of the materials relevant to applications and as a probe of electronic structure. Different experimental and theoretical methods for probing EPC are outlined. Results for several different classes of II-VI nanocrystals are summarized. Finally, possible future directions are outlined.
Plasma generation using time reversal of microwaves
Authors: Mazières Valentin , Pascaud Romain , Liard Laurent , Dap Simon , Clergereaux Richard , Pascal Olivier
Published: October 2019

We report the experimental demonstration of plasma generation by time-reversal focusing. After a learning phase, the amplified time reversed signal built at a central frequency of 2.45 GHz injected in a low loss metallic cavity allows us to ignite and maintain a localized centimeter-sized plasma in argon at 133 Pa. The plasma spatial position is totally controlled by the signal waveform.
Balance-equation method for simulating terahertz quantum-cascade lasers using a wave-function basis with reduced dipole moments of tunnel-coupled states
Authors: Ushakov D.V. , Afonenko A.A. , Dubinov A.A. , Gavrilenko V.I. , Volkov O.Yu. , Shchavruk N.V. , Ponomarev D.S. , Khabibullin R.A.
Published: October 2019

A model based on a system of balance equations for localised and continuum states is developed to calculate the current − voltage (I − V) and power characteristics of quantum-cascade lasers (QCLs) operating in the terahertz (THz) range. A method for modifying the eigenbasis of the Schrödinger equation by reducing the dipole moments of tunnel-coupled states is proposed to take into account the effect of dephasing on the carrier transport. The calculated and experimental data on the current − voltage characteristics and the dependence of the integrated radiation intensity on current for the THz QCLs lasing at 2.3 THz are compared. The calculated and measured values of the threshold current, lasing current range, and maximum operating temperature T
max are found to be in good agreement. It is shown that T
max can be increased by 25 % by reducing the thickness of the top contact layer n
+-GaAs of the laser structure under study from 800 to 100 nm.
Superluminescent diodes based on asymmetric double-quantum-well heterostructures
Authors: Andreeva E.V. , Il’chenko S.N. , Ladugin M.A. , Marmalyuk A.A. , Pankratov K.M. , Shidlovskii V.R. , Yakubovich S.D.
Published: October 2019

The power and spectral characteristics of near-IR superluminescent diodes (SLDs) based on asymmetric double-quantum-well GaAs/InGaAs heterostructures are studied experimentally. It is shown that, varying the active layer composition and the spatial-single-mode active channel length of these SLDs, it is possible to widely change the achievable output optical power and the spectral width of the symmetric bell-shaped spectrum. The studied SLDs have a lower coherence function pedestal, a weaker dependence of the spectral width on the injection current, and a higher polarisation degree than the widely spread SLDs based on single-quantum-well heterostructures with the same spectral widths.
Linking scaling laws across eukaryotes
Authors: Hatton Ian A. , Dobson Andy P. , Storch David , Galbraith Eric D. , Loreau Michel
Published: October 2019

Significance

Metabolic scaling theory has had a profound influence on ecology, but the core links between species characteristics have not been formally tested across the full domain to which the theory claims to apply. We compiled datasets spanning all eukaryotes for the foremost body mass scaling laws: metabolism, abundance, growth, and mortality. We show that metabolism and abundance scaling only follow the canonical ±3/4 slopes within some taxonomic groups, but across eukaryotes reveal reciprocal near ±1 slopes, broadly supporting the “energetic equivalence rule.” In contrast to metabolism, growth follows consistent ∼3/4 scaling within many groups and across all eukaryotes. Our findings are incompatible with a metabolic basis for growth scaling and instead point to growth dynamics as foundational to biological scaling.
Climate-driven regime shifts in a mangrove–salt marsh ecotone over the past 250 years
Authors: Cavanaugh Kyle C. , Dangremond Emily M. , Doughty Cheryl L. , Williams A. Park , Parker John D. , Hayes Matthew A. , Rodriguez Wilfrid , Feller Ilka C.
Published: October 2019

Significance

In recent years, tropical species have expanded poleward into temperate regions. For example, along the east coast of North America, mangroves have expanded into salt marshes in response to decreases in the frequency of extreme freezes. But questions remain about how mangrove abundance has changed over longer timescales and the role of anthropogenic climate change. We used a mixed methods approach to document a series of climate-driven shifts in mangrove abundance over the past 250 y. However, climate model projections suggest warming may push this fluctuating system toward a persistent state of mangrove dominance. This historical approach can be applied to a variety of ecosystems to place the effects of climate change in the context of long-term natural climate variability.
Divergent roles of astrocytic versus neuronal EAAT2 deficiency on cognition and overlap with aging and Alzheimer’s molecular signatures
Authors: Sharma Abhijeet , Kazim Syed Faraz , Larson Chloe S. , Ramakrishnan Aarthi , Gray Jason D. , McEwen Bruce S. , Rosenberg Paul A. , Shen Li , Pereira Ana C.
Published: October 2019

Significance

The excitatory amino acid transporter 2 (EAAT2) is the predominant glutamate transporter in the mammalian brain, and its expression is reduced in aging and sporadic Alzheimer’s disease (AD) brains. The mechanisms through which reduced EAAT2 expression contributes to cognitive decline and AD-related neurodegeneration and the differential functional roles of its astrocytic and neuronal components remain largely unknown. This study uses behavioral analysis to show that astrocytic and neuronal EAAT2 deficiency in mice causes age-dependent cognitive dysfunction. Furthermore, we show that gene expression from human AD and aging datasets have a robust overlap with astrocytic EAAT2 deficiency. This study highlights the distinct signaling mechanisms mediated by neuronal and astrocytic EAAT2 and EAAT2 as a potential therapeutic target in aging and AD.
DNA methyltransferase inhibitors induce a BRCAness phenotype that sensitizes NSCLC to PARP inhibitor and ionizing radiation
Authors: Abbotts Rachel , Topper Michael J. , Biondi Christopher , Fontaine Daniel , Goswami Reena , Stojanovic Lora , Choi Eun Yong , McLaughlin Lena , Kogan Aksinija A. , Xia Limin , Lapidus Rena , Mahmood Javed , Baylin Stephen B. , Rassool Feyruz V.
Published: October 2019

Significance

We introduce a key role for low doses of DNA methyltransferase inhibitors (DNMTis) in reprogramming the DNA repair transcriptome and creating a homologous recombination defect (HRD), sensitizing to poly (ADP-ribose) polymerase (PARP) inhibitors (PARPis) in breast cancer gene (BRCA)-proficient nonsmall cell lung cancer (NSCLC), which are not clinically responsive to PARPis. The nonhomologous end-joining pathway is also downregulated by DNMTis, generating sensitivity to radiation therapy (RT). The significant increases in antitumor effects with DNMTi and PARPis in combination with RT suggest a potentially potent therapeutic strategy for patients with BRCA-proficient NSCLC, for whom limited therapy is available.
The rhizobial type III effector ErnA confers the ability to form nodules in legumes
Authors: Teulet Albin , Busset Nicolas , Fardoux Joël , Gully Djamel , Chaintreuil Clémence , Cartieaux Fabienne , Jauneau Alain , Comorge Virginie , Okazaki Shin , Kaneko Takakazu , Gressent Frédéric , Nouwen Nico , Arrighi Jean-François , Koebnik Ralf , Mergaert Peter , Deslandes Laurent , Giraud Eric
Published: October 2019

Significance

Legumes have a tremendous ecological and agronomic importance due to their ability to interact symbiotically with nitrogen-fixing rhizobia. In most of the rhizobial–legume symbioses, the establishment of the interaction requires the plant perception of the bacterial lipochitooligosaccharide Nod factor signal. However, some bradyrhizobia can activate the symbiosis differently, thanks to their type III secretion system, which delivers effector proteins into the host cell. Here, we demonstrate that this symbiotic process relies on a small set of effectors playing distinct and complementary roles. Most remarkably, a nuclear-targeted effector named ErnA conferred the ability to form nodules. The understanding of this alternative pathway toward nitrogen-fixing symbiosis could pave the way for designing new strategies to transfer nodulation into cereals.
Recurrence is required to capture the representational dynamics of the human visual system
Authors: Kietzmann Tim C. , Spoerer Courtney J. , Sörensen Lynn K. A. , Cichy Radoslaw M. , Hauk Olaf , Kriegeskorte Nikolaus
Published: October 2019

Significance

Understanding the computational principles that underlie human vision is a key challenge for neuroscience and could help improve machine vision. Feedforward neural network models process their input through a deep cascade of computations. These models can recognize objects in images and explain aspects of human rapid recognition. However, the human brain contains recurrent connections within and between stages of the cascade, which are missing from the models that dominate both engineering and neuroscience. Here, we measure and model the dynamics of human brain activity during visual perception. We compare feedforward and recurrent neural network models and find that only recurrent models can account for the dynamic transformations of representations among multiple regions of visual cortex.
A structure-based rationale for sialic acid independent host-cell entry of Sosuga virus
Authors: Stelfox Alice J. , Bowden Thomas A.
Published: October 2019

The bat-borne paramyxovirus, Sosuga virus (SosV), is one of many paramyxoviruses recently identified and classified within the newly established genus
Pararubulavirus
, family
Paramyxoviridae
. The envelope surface of SosV presents a receptor-binding protein (RBP), SosV-RBP, which facilitates host-cell attachment and entry. Unlike closely related hemagglutinin neuraminidase RBPs from other genera of the
Paramyxoviridae
, SosV-RBP and other pararubulavirus RBPs lack many of the stringently conserved residues required for sialic acid recognition and hydrolysis. We determined the crystal structure of the globular head region of SosV-RBP, revealing that while the glycoprotein presents a classical paramyxoviral six-bladed β-propeller fold and structurally classifies in close proximity to paramyxoviral RBPs with hemagglutinin-neuraminidase (HN) functionality, it presents a receptor-binding face incongruent with sialic acid recognition. Hemadsorption and neuraminidase activity analysis confirms the limited capacity of SosV-RBP to interact with sialic acid in vitro and indicates that SosV-RBP undergoes a nonclassical route of host-cell entry. The close overall structural conservation of SosV-RBP with other classical HN RBPs supports a model by which pararubulaviruses only recently diverged from sialic acid binding functionality.
Immune effector monocyte–neutrophil cooperation induced by the primary tumor prevents metastatic progression of breast cancer
Authors: Hagerling Catharina , Gonzalez Hugo , Salari Kiarash , Wang Chih-Yang , Lin Charlene , Robles Isabella , van Gogh Merel , Dejmek Annika , Jirström Karin , Werb Zena
Published: October 2019

Metastatic behavior varies significantly among breast cancers. Mechanisms explaining why the majority of breast cancer patients never develop metastatic outgrowth are largely lacking but could underlie the development of novel immunotherapeutic target molecules. Here we show interplay between nonmetastatic primary breast cancer and innate immune response, acting together to control metastatic progression. The primary tumor systemically recruits IFNγ-producing immune effector monocytes to the lung. IFNγ up-regulatesTmem173/STINGin neutrophils and enhances their killing capacity. The immune effector monocytes and tumoricidal neutrophils target disseminated tumor cells in the lungs, preventing metastatic outgrowth. Importantly, our findings could underlie the development of immunotherapeutic target molecules that augment the function of immune effector monocytes and neutrophils.
Early hominins evolved within non-analog ecosystems
Authors: Faith J. Tyler , Rowan John , Du Andrew
Published: October 2019

Significance

Testing ecological hypotheses of human evolution requires an understanding of the ancient plant and animal communities within which our ancestors lived. Though present-day ecosystems provide the baseline for reconstructing the ecological context of human evolution, the extent to which modern ecosystems are representative of past ones is unknown. Through analyses of a fossil dataset spanning the last 7 Myr, we show that eastern African communities of large-bodied mammalian herbivores differed markedly from those today until ∼700,000 y ago. Because large herbivores are ecosystem engineers and shape biotic communities in ways that impact a wide variety of species, this implies that the vast majority of early human evolution transpired in the context of ecosystems that functioned unlike any known today.
Molecular profiling predicts meningioma recurrence and reveals loss of DREAM complex repression in aggressive tumors
Authors: Patel Akash J. , Wan Ying-Wooi , Al-Ouran Rami , Revelli Jean-Pierre , Cardenas Maria F. , Oneissi Mazen , Xi Liu , Jalali Ali , Magnotti John F. , Muzny Donna M. , Doddapaneni HarshaVardhan , Sebastian Sherly , Heck Kent A. , Goodman J. Clay , Gopinath Shankar P. , Liu Zhandong , Rao Ganesh , Plon Sharon E. , Yoshor Daniel , Wheeler David A. , Zoghbi Huda Y. , Klisch Tiemo J.
Published: October 2019

Meningiomas account for one-third of all primary brain tumors. Although typically benign, about 20% of meningiomas are aggressive, and despite the rigor of the current histopathological classification system there remains considerable uncertainty in predicting tumor behavior. Here, we analyzed 160 tumors from all 3 World Health Organization (WHO) grades (I through III) using clinical, gene expression, and sequencing data. Unsupervised clustering analysis identified 3 molecular types (A, B, and C) that reliably predicted recurrence. These groups did not directly correlate with the WHO grading system, which classifies more than half of the tumors in the most aggressive molecular type as benign. Transcriptional and biochemical analyses revealed that aggressive meningiomas involve loss of the repressor function of the DREAM complex, which results in cell-cycle activation; only tumors in this category tend to recur after full resection. These findings should improve our ability to predict recurrence and develop targeted treatments for these clinically challenging tumors.
Mother-to-embryo vitellogenin transport in a viviparous teleost
Xenotoca eiseni
Authors: Iida Atsuo , Arai Hiroyuki N. , Someya Yumiko , Inokuchi Mayu , Onuma Takeshi A. , Yokoi Hayato , Suzuki Tohru , Hondo Eiichi , Sano Kaori
Published: October 2019

Significance

Viviparity is a type of reproductive system in which the embryo utilizes a maternal nutrient supply until birth. Viviparous species occur in many taxa including bony fish. The mother fish raises her offspring in the ovarian lumen or oviduct during gestation. Embryos of the viviparous bony fish
Xenotoca eiseni
(family Goodeidae) utilize nutrients secreted into the ovarian lumen. However, the source of the maternal nutrients and their mother-to-embryo transport have not been experimentally demonstrated. In this study, we focus on the yolk nutrient protein vitellogenin (Vtg) as a matrotrophic factor. Our results are of fundamental importance to the investigation of viviparous systems in teleosts and in other vertebrates and invertebrates.
Path integral molecular dynamics for bosons
Authors: Hirshberg Barak , Rizzi Valerio , Parrinello Michele
Published: October 2019

Trapped bosons exhibit fundamental physical phenomena and are at the core of emerging quantum technologies. We present a method for simulating bosons using path integral molecular dynamics. The main difficulty in performing such simulations is enumerating all ring-polymer configurations, which arise due to permutations of identical particles. We show that the potential and forces at each time step can be evaluated by using a recurrence relation which avoids enumerating all permutations, while providing the correct thermal expectation values. The resulting algorithm scales cubically with system size. The method is tested and applied to bosons in a 2-dimensional (2D) trap and agrees with analytical results and numerical diagonalization of the many-body Hamiltonian. An analysis of the role of exchange effects at different temperatures, through the relative probability of different ring-polymer configurations, is also presented.
Unraveling the structure and dynamics of the human DNAJB6b chaperone by NMR reveals insights into Hsp40-mediated proteostasis
Authors: Karamanos Theodoros K. , Tugarinov Vitali , Clore G. Marius
Published: October 2019

J-domain chaperones are involved in the efficient handover of misfolded/partially folded proteins to Hsp70 but also function independently to protect against cell death. Due to their high flexibility, the mechanism by which they regulate the Hsp70 cycle and how specific substrate recognition is performed remains unknown. Here we focus on DNAJB6b, which has been implicated in various human diseases and represents a key player in protection against neurodegeneration and protein aggregation. Using a variant that exists mainly in a monomeric form, we report the solution structure of an Hsp40 containing not only the J and C-terminal substrate binding (CTD) domains but also the functionally important linkers. The structure reveals a highly dynamic protein in which part of the linker region masks the Hsp70 binding site. Transient interdomain interactions via regions crucial for Hsp70 binding create a closed, autoinhibited state and help retain the monomeric form of the protein. Detailed NMR analysis shows that the CTD (but not the J domain) self-associates to form an oligomer comprising ∼35 monomeric units, revealing an intricate balance between intramolecular and intermolecular interactions. The results shed light on the mechanism of autoregulation of the Hsp70 cycle via conserved parts of the linker region and reveal the mechanism of DNAJB6b oligomerization and potentially antiaggregation.
Technology-mediated task-based interaction
Authors: Ziegler Nicole , Phung Huy
Published: October 2019

This exploratory study examines the extent to which mode differentially impacts the quantity and quality of
interactional features in second language (L2) task-based interaction. Following a within-subject, repeated measures design,
intermediate adult learners (n = 20) completed four (counter-balanced) tasks with a confederate interlocutor in
the following conditions: audio-chat, video-chat, text-chat, and multimodal chat (in which participants could interact using more
than one form of communication). Quantitative analyses examined the quality of learners’ interactions, including negotiation,
recasts, and LREs. Data regarding learners’ perceptions of type of technology were also collected to provide a more holistic
perspective. The results demonstrate differences in terms of interactional features and learners’ preference based on mode of
technology.
The value of introspective measures in aptitude-treatment interaction research
Authors: Sachs Rebecca , Akiyama Yuka , Nakatsukasa Kimi
Published: October 2019

To explore the value of introspective measures in aptitude-treatment interaction (ATI) research, this study
analyzed the cognitive profiles and concurrent think-alouds of six university learners of Japanese who were highly successful,
moderately successful, or unsuccessful under two computer-mediated feedback conditions in a larger (N = 80)
quantitative ATI investigation (Sachs, 2011). That study had made indirect inferences
regarding relationships among individual differences (IDs), cognitive processes, and learning on the basis of correlational
results. Using Leow’s (2015) depth-of-processing (DoP) framework as a lens, what we
found in the qualitative verbalization data highlighted that learners in the same condition with similar strengths in the IDs that
are statistically associated with performance at the group level may nonetheless engage in different cognitive processes and
achieve different learning outcomes, and vice versa. The findings also pointed toward more complex ID-DoP and ID-ID interactions
that future research could explore, such as the possibility that a weakness in memory might limit the benefits of metalinguistic
knowledge and analytic processing in a condition where group-level correlations suggest analysis is relevant to success, or that
analytic processing might enhance the value of memory in a condition where memory is relevant to success. In our conclusions, we
argue for the value of mixed-methods research in this area.
III–V ternary nanowires on Si substrates: growth, characterization and device applications
Authors: Boras Giorgos , Yu Xuezhe , Liu Huiyun
Published: October 2019

Over the past decades, the progress in the growth of materials which can be applied to cutting-edge technologies in the field of electronics, optoelectronics and energy harvesting has been remarkable. Among the various materials, group III–V semiconductors are of particular interest and have been widely investigated due to their excellent optical properties and high carrier mobility. However, the integration of III–V structures as light sources and numerous other optical components on Si, which is the foundation for most optoelectronic and electronic integrated circuits, has been hindered by the large lattice mismatch between these compounds. This mismatch results in substantial amounts of strain and degradation of the performance of the devices. Nanowires (NWs) are unique nanostructures that induce elastic strain relaxation, allowing for the monolithic integration of III–V semiconductors on the cheap and mature Si platform. A technique that ensures flexibility and freedom in the design of NW structures is the growth of ternary III–V NWs, which offer a tuneable frame of optical characteristics, merely by adjusting their nominal composition. In this review, we will focus on the recent progress in the growth of ternary III–V NWs on Si substrates. After analysing the growth mechanisms that are being employed and describing the effect of strain in the NW growth, we will thoroughly inspect the available literature and present the growth methods, characterization and optical measurements of each of the III–V ternary alloys that have been demonstrated. The different properties and special treatments required for each of these material platforms are also discussed. Moreover, we will present the results from the works on device fabrication, including lasers, solar cells, water splitting devices, photodetectors and FETs, where ternary III–V NWs were used as building blocks. Through the current paper, we exhibit the up-to-date state in this field of research and summarize the important accomplishments of the past few years.
Simulation of structural design with high coupling efficiency in external cavity semiconductor laser
Authors: Zhang Yangjie , Guo Wentao , Xiong Di , Guo Xiaofeng , Liao Wenyuan , Liu Haifeng , Liu Weihua , Tan Manqing
Published: October 2019

For external cavity semiconductor lasers (ECSLs), high coupling efficiency is critical to reducing the linewidth. In this paper, the coupling efficiency between the laser diode and the waveguide grating has been improved, with proposals for its improvement presented, including adding spot-size conversion (SSC) and using a silicon-on-insulator (SOI) waveguide. The results indicate an increase of coupling efficiency from 41.5% to 93.1%, which exhibits an improvement of approximately 51.6% over conventional schemes. The relationship between coupling efficiency and SOI waveguide structures is mainly concerned in this article. These findings provide a new way for the future research of the narrow linewidth of ECSL.