bluuebunny/crossref_metadata_2025 huggingface dataset:
Factors Associated with Pediatric In-Hospital Recurrent Cardiac Arrest
Authors: Brown Stephanie R. , Roberts Joan S. , Killien Elizabeth Y. , Brogan Thomas V. , Farris Reid , Di Gennaro Jane L. , Barreto Jessica , McMullan D. Michael , Weiss Noel S.
Published: January 2022

The objective of this article was to identify demographic and clinical factors associated with early recurrent arrest (RA; <48 hours) and late RA (≥48 hours) among pediatric inpatients following an initial in-hospital cardiac arrest. A retrospective cohort study of inpatients was performed in a free-standing academic quaternary care children's hospital. All inpatients were <18 years old with a cardiac arrest event requiring ≥1 minute of cardiopulmonary resuscitation with the return of spontaneous circulation sustained for ≥20 minutes at Seattle Children's Hospital from February 1, 2012, to September 18, 2019. Of the 237 included patients, 20 (8%) patients had an early RA and 30 (13%) had a late RA. Older age and severe prearrest acidosis were associated with a higher risk of early RA, odds ratios (OR) = 1.2 (95% confidence interval [CI]: 1.1–1.3) per additional year and 4.6 (95% CI: 1.2–18.1), respectively. Prearrest organ dysfunction was also associated with a higher risk of early RA with an OR of 3.3 (95% CI: 1.1–9.4) for respiratory dysfunction, OR = 1.4 (95% CI: 1.1–1.9) for each additional dysfunctional organ system, and OR = 1.1 (95% CI: 1–1.2) for every one-point increase in PELOD2 score. The neonatal illness category was associated with a lower risk of late RA, OR 0.3 (95% CI: 0.1–0.97), and severe postarrest acidosis was associated with a higher risk of late RA, OR = 4.2 (95% CI: 1.1–15). Several demographic and clinical factors offer some ability to identify children who sustain a recurrent cardiac arrest, offering a potential opportunity for intervention to prevent early recurrent arrest.
Silk materials at the convergence of science, sustainability, healthcare, and technology
Authors: Guidetti Giulia , d'Amone Luciana , Kim Taehoon , Matzeu Giusy , Mogas-Soldevila Laia , Napier Bradley , Ostrovsky-Snider Nicholas , Roshko Jeffery , Ruggeri Elisabetta , Omenetto Fiorenzo G.
Published: January 2022

Over the past few decades, Bombyx mori silk fibroin has become a ubiquitous material for applications ranging from biomedical devices to optics, electronics, and sensing, while also showing potential in the food supply chain and being re-engineered as a functional material for architecture and design-related applications. Its widespread use derives from its unique properties, including biocompatibility, edibility, optical transparency, stabilization of labile compounds, and the ability to controllably change conformation and degrade in a programmed way. This review discusses recent and pivotal silk-based devices in which the presence of silk brings added value in terms of functionality, as demonstrated in a broad variety of fields. First, it gives an overview of silk's natural structure and main properties in terms of cross-linking, biocompatibility, and biodegradability to provide the reader with the necessary toolbox to fully make use of silk's multifaceted properties. Then, multifunctional silk-based devices are discussed highlighting the advantage of using silk over more traditional materials. Representative devices from both established and emerging applications for silk are examined. Finally, a roadmap for the next generation of silk-based devices is laid out.
High absorption efficiency by high intensity laser irradiating carbon aerogel targets
Authors: Li Xiaoxiao , Yang Xiaohu , Zhang Guobo , Ma Yanyun , Jiao Jinlong , Shan Fei , Han Peng , Ma Long , Peng Meng , Feng Junzong
Published: January 2022

We have proposed a scheme to increase the ultra-intense femtosecond laser absorption efficiency by using carbon aerogel targets. Particle-in-cell simulations show that, compared to a homogeneous target of the same density, the carbon aerogel target can significantly enhance the laser absorption efficiency, and the maximum laser absorption efficiency can reach 88%. Such high absorption efficiency can be attributed to the porous structure and larger surface area of carbon aerogel than ordinary materials, which allows the laser to enter more of the target and interact more fully with the particles inside rather than being reflected off the surface. By studying the interaction between the laser and the carbon aerogel targets, we found that both the nanoparticle diameter and porosity have great effects on the laser absorption efficiency, which is enhanced significantly as the nanoparticle diameter and porosity increase. Such carbon aerogel targets should have significant applications in the fields of laser generation of x rays and high energy density physics.
Quaternary alloy ScAlGaN: A promising strategy to improve the quality of ScAlN
Authors: Wang Ping , Wang Ding , Bi Yutong , Wang Boyu , Schwartz Jonathan , Hovden Robert , Mi Zetian
Published: January 2022

ScAlN is an emerging ultrawide bandgap semiconductor for next-generation radio frequency electronic devices. Here, we show that the material quality of ScAlN grown by molecular beam epitaxy can be drastically improved by alloying with Ga. The resulting quaternary alloy ScAlGaN exhibits a single-phase wurtzite structure, atomically smooth surface, high crystal quality, sharp interface, and low impurity concentration. Most significantly, oxygen impurity incorporation in ScAlGaN is found to be three to four orders of magnitude lower compared to that for ScAlN grown on AlN templates utilizing a similar Sc source. We further demonstrate that ScAlGaN/GaN superlattices exhibit clear periodicity with sharp interfaces. Moreover, GaN high electron mobility transistors with high sheet electron density and high mobility have been realized using ScAlGaN as a barrier. This work provides a viable approach for achieving high-quality Sc-III-N semiconductors that were not previously possible and further offers additional dimensions for bandgap, polarization, interface, strain, and quantum engineering.
Level spacing statistics for the multi-dimensional quantum harmonic oscillator: Algebraic case
Authors: Haynes Alan , Roeder Roland
Published: January 2022

We study the statistical properties of the spacings between neighboring energy levels for the multi-dimensional quantum harmonic oscillator that occur in a window [E, E + ΔE) of fixed width ΔE as E tends to infinity. This regime provides a notable exception to the Berry–Tabor conjecture from quantum chaos, and, for that reason, it was studied extensively by Berry and Tabor in their seminal paper from 1977. We focus entirely on the case that the (ratios of) frequencies ω1, ω2, …, ωd together with 1 form a basis for an algebraic number field Φ of degree d + 1, allowing us to use tools from algebraic number theory. This special case was studied by Dyson, Bleher, Bleher–Homma–Ji–Roeder–Shen, and others. Under a suitable rescaling, we prove that the distribution of spacings behaves asymptotically quasiperiodically in log E. We also prove that the distribution of ratios of neighboring spacings behaves asymptotically quasiperiodically in log E. The same holds for the distribution of finite words in the finite alphabet of rescaled spacings. Mathematically, our work is a higher dimensional version of the Steinhaus conjecture (three gap theorem) involving the fractional parts of a linear form in more than one variable, and it is of independent interest from this perspective.
Posture adjustment and robust microinjection of zebrafish larval heart
Authors: Fan Qigao , Zhang Hai , Qu Juntian , Xie Linbo , Huang Wentao , Zhu Yixin , Bi Kaitao , Lu Wenzhou
Published: January 2022

Unlike cells or embryos, zebrafish have a complex physiological structure, which poses challenges to posture recognition and adjustment during microinjection. Furthermore, zebrafish surface pigments exhibit strong interference with visual servo-based injection control, thus, affecting the success of microinjection and the subsequent survival rate. To address these challenges, we developed an automated microinjection system for the zebrafish heart that has advantages of high accuracy and success rate and avoids biological sample contamination. A convolutional neural networks (CNN) deep learning model is employed to determine the body axis posture. To solve the problems of blocked needle and abnormal tip positioning induced by zebrafish surface pigment during the injection process, an adaptive robust Kalman filter is proposed to suppress the abnormal values of visual feedback. Experimental results show that the success rate of body axis recognition based on the employed deep learning model exceeds 95%, and the proposed adaptive Kalman filter effectively suppresses the visual outliers, satisfying the requirements of high-precision injection for the zebrafish heart.
Accelerated design for elastocaloric performance in NiTi-based alloys through machine learning
Authors: Tian Xiaohua , Zhao Qiu , Zhang Kun , Li Hongxing , Han Binglun , Shi Dingding , Zhou Liwen , Ma Tianyou , Wang Cheng , Wen Qinlong , Tan Changlong
Published: January 2022

NiTi-based shape memory alloys (SMAs) are regarded as one of the most promising materials for engineering applications of elastocaloric refrigeration. A critical mission is to efficiently explore the new NiTi-based SMAs with large adiabatic temperature change (ΔTad). We proposed a new material design method that combines highly correlated microscale physical information (volume change, ΔV) into machine learning to predict ΔTad of NiTi-based alloys. First, we tightly coupled machine learning with first-principles calculations to accelerate receiving lattice parameters before and after the phase transformation and predict the ΔV, which shows excellent performance with the coefficient of determination R2 > 0.99. Then, relevant features, including the ΔV, are considered to predict the ΔTad in NiTi-based SMAs. Moreover, due to the small dataset, the principal component analysis and the independent component analysis are added. We evaluate the performance of three machine learning models [Lasso regression, support vector regression, and decision tree regression (DTR)]. Finally, the DTR model exhibits a high accuracy for predicting ΔTad (R2 > 0.9). Introducing the feature of ΔV into the machine learning process can improve the accuracy and efficiency of model design. Further, this work paves the way to accelerate the discovery of new excellent materials for practical applications of elastocaloric refrigeration.
Piezo-phototronics in quantum well structures
Authors: Dai Xinhuan , Hua Qilin , Sha Wei , Wang Jiangwen , Hu Weiguo
Published: January 2022

Quantum well (QW) structures are formed in nanometer-thickness-scale semiconductors with different bandgaps in sandwiched configurations and can offer a wide variety of advantages as active layers for optoelectronic devices, e.g., laser diodes, light emit diodes, photodetectors, and solar cells. Due to the non-centrosymmetric crystal structure, the third-generation semiconductor, such as ZnO, AlN, GaN, and InN, can generate a piezopotential within the crystal by applying an external or internal strain and lead to an effective modulation of the optoelectronic device performance, which is also called piezo-phototronics. With reducing the feature size of materials into several tens of nanometers (e.g., forming QW structures), the multiway coupling effects of quantum physics and piezo-phototronics (coupling with piezoelectricity, photoexcitation, and semiconductor properties) make this research topic more attractive and open a new window for fabricating advanced intelligent optoelectronic devices. This Perspective reviews the recent advances of piezo-phototronics in QW structures, including the fundamental theories and device performance enhancements, and aims to offer a summary and outlook for future research directions and practical applications of piezo-phototronic QW devices.
Discharge characteristics of a microsecond pulse power supply driven air plasma jet and its anticancer cell effect
Authors: Peng Sansan , Qi Miao , Zhang Huaiyan , Zhang Jin , Liu Rong , Pang Bolun , Zhang Xinying , Liu Zhijie , Zhang Hao , Liu Dingxin , Xu Dehui
Published: January 2022

In plasma cancer therapy, atmospheric pressure plasma jets have attracted increasing attention in recent years. In this study, from the point of view of economic costs and portability, we have employed atmospheric air as the working gas in order to investigate the effects of the rate of flow, applied voltage, frequency, and pulse width on the characteristics of discharge. The concentrations of reactive oxygen and nitrogen species (RONS) in a plasma-activated medium (PAM) were characterized in order to explore their chemical activity. In addition, the inactivating effect of tumor cells induced by an air plasma jet was investigated and the corresponding inactivation mechanism is also discussed. The results showed that the discharge intensity was positively correlated with frequency and voltage, and negatively correlated with pulse width. Regarding the gas flow rate, when the air flow rate was 1 standard liter per minute (SLM), the discharge intensity was strongest according to the length of the plume. By summarizing the discharge characteristics and emission spectra under different experimental parameters, the stable treatment conditions producing rich active substances were as follows: a frequency of 6 kHz, a voltage of 14 kV, a gas flow rate of 1 SLM, and a pulse width of 1 μs. Furthermore, under these stabilized conditions, the air plasma jet produced rich aqueous RONS in a PAM effectively, which killed cells in significant numbers and reduced the cell survival rate. Therefore, this study demonstrates the potential application of an atmospheric PAM for the treatment of tumor cells and promotes a deeper understanding of plasma liquid chemistry.
Surface passivation of halide perovskite nanocrystals for stable and high purity color conversion
Authors: Wang Xianghua , Li Wenbin , Zhao Xudong , Fu Jing , Zhang Guobing , Ma Wei , Zhang Wen-Hua , Choi Hoi Wai
Published: January 2022

Surface passivation using aminopropyl-functionalized siloxane is proposed via a post-synthesis ligand exchange reaction. The near-unity photoluminescence quantum yield (PLQY) is explained by more efficient surface passivation, which is confirmed by transient PL measurements. Alternatively, the siloxane can be introduced during the hot-injection synthesis, and a thicker SiO2 shell structure is formed on the surface of nanocrystals (NCs), which leads to agglomeration and degrades optical properties. The low-temperature ligand exchange reaction lends precision process control; thereby, an optimized PLQY of 99% is achieved. Moreover, the emission wavelength of the siloxane passivated CsPbBr3 can be modulated via halide exchange for highly saturated and stable green emissions. The stability of these NCs is first ascribed to the siloxane moiety. Siloxane passivated CsPbI3 NCs were also prepared with bright red emission. A wide color gamut of 134.9% National Television System Committee or 100.7% Rec. 2020 is realized using blue light-emitting diodes together with green and red perovskite NCs. We stress the effect of Cs vacancy repair via the ligand exchange and the essentially monolayer thickness of the ligand shell to ascribe the high performance of these NCs.
Spin transport in fully ferromagnetic p–n junctions
Authors: Thanh Tu Nguyen , Otsuka Tomohiro , Arakawa Yuto , Anh Le Duc , Tanaka Masaaki , Hai Pham Nam
Published: January 2022

We systematically investigate the spin-dependent transport properties of fully ferromagnetic (Ga,Fe)Sb/GaSb/(In,Fe)Sb and (Ga,Fe)Sb/(In,Fe)As p–n junctions grown by low-temperature molecular beam epitaxy. The (Ga,Fe)Sb/GaSb/(In,Fe)Sb p–n junctions show high Curie temperature (170–310 K) and rectifying characteristics. The polarity and magnitude of magnetoresistance of the (Ga,Fe)Sb/GaSb/(In,Fe)Sb junctions strongly depend on the GaSb spacer thickness (t). Large positive magnetoresistance (MR, 58%) and negative MR (−1.6%) were observed at 3.7 K for the samples with t = 2 and 4 nm, respectively. When the n-type (In,Fe)Sb layer was replaced by the n-type (In,Fe)As, giant MR over 500% was observed, which can be explained by spin-valve and spin-splitting effects. Our results shed light on rich spin-transport physics observed in fully ferromagnetic p–n junctions.
Axial compressive stress for depolarization suppression and source level enhancement of underwater projectors made of [011]-poled PZN-PT single crystals
Authors: Zhang Shuangjie , Song Piqi , Zhao Shuxiang , Chu Zhaoqiang , Mao Zhineng , Gao Junqi , Lim Leong-Chew
Published: January 2022

Lead-based relaxor-PT single crystals of rhombohedral phase, such as Pb(Zn1/3Nb2/3)O3-PbTiO3 and Pb(Mg1/3Nb2/3)O3-PbTiO3, exhibit excellent piezoelectric properties and are candidate active materials for high-performance underwater projectors. However, their low coercive field would cause depolarization under high ac drive field, making them unsuitable for high power applications. The present work investigates the effect of axial compressive stress on the depolarization and phase transition behaviors of [011]-poled 32-mode PZN-5.5%PT single crystals. Our results show that with appropriate compressive stress in the [100]-crystal direction, the magnitude of depolarization field of the crystal can be increased to close to the R-O phase transformation field, enabling the application of higher ac drive field. The result further shows that with optimal axial compressive stress, >5 dB increase in the figure-of-merit (FOM) can be achieved without dc bias. The effect of axial compressive stress on material properties of [011]-poled 32-mode PZN-5.5%PT single crystals are also presented, which are useful for underwater projector design purposes.
Axial force transmission in flexible bowtie dielectric elastomer actuators
Authors: Lau Gih-Keong , Chen Fa-Yi , Ren Zhe-Xian
Published: January 2022

A long strip of a pre-stretched dielectric elastomer actuator (DEA) is necessary for strain accumulation, but it relaxes laterally and thickens non-uniformly. As compared to a short strip under the same voltage activation, the long relaxed strip is subjected to a less electric field and, thus, undergoes less active strain. Here, we developed a flexible ladder frame to reinforce and divide the long DEA in a bowtie series. When being pulled, the ladder frame unbuckled; it, in turn, helped to pre-stretch tautly the DEA membrane. Interestingly, its flanges enhance force transmissions, acting like tensioning cables for a suspension bridge. Hence, the maximum isometric stress of this bowtie series was 24% higher than the short pure-shear one and 6.5 times the long uniaxial one. With 2.2 times enhanced dielectric strength across a taut DEA membrane, the bowtie series generated an isotonic strain 3.2 times that a long non-reinforced and relaxed DEA did. Hence, the reinforced DEAs can provide a more forceful drive for bio-inspired robots.
A statistical analysis of velocity and acceleration fluctuations of inertial particles in particle-laden turbulent Couette flow
Authors: Ghosh S. , Goswami P. S.
Published: January 2022

Dynamics of the particle phase in a particle-laden turbulent flow is strongly influenced by the fluctuating velocity and vorticity field of the fluid phase. The present work mainly focuses on exploring the statistics of velocity and acceleration of the particle phase in a particle-laden turbulent Couette flow. Direct numerical simulations have been performed for particle-laden turbulent Couette flow with two different Reynolds numbers, Reδ=750 and 1300, in the presence of sub-Kolmogorov sized inertial particles for multiple Stokes numbers (Stokes number ≫1). The inter-particle and wall-particle interactions have also been considered to be elastic. We report the distribution functions for the linear and rotational velocities and accelerations in the presence of particle roughness. From the particle equation of rotational motion, we arrive at the expression where the fluctuating angular acceleration αi′ of the particle is expressed as the ratio of a linear combination of fluctuating rotational velocities of particle (ωi′) and fluid angular velocity (Ωi′) to the particle rotational relaxation time τr. The analysis is done using probability density function plots and Jensen–Shannon divergence-based method to assess the similarity between the particle net rotational acceleration distributions f(αi′), with (i) the distributions of particle acceleration component arises from fluctuating fluid angular velocity computed in the particle-Lagrangian frame f((Ω′i/τr)pl), (ii) fluctuating particle angular velocity f(ω′i/τr), and (iii) the fluid angular velocity f((Ω′i/τr)e) computed in the fluid Eulerian grids. The analysis leads to the conclusion that for a wide range of Reynolds and Stokes numbers, f(αi′) can be represented with a Gaussian white noise with a pre-estimated strength that can be calculated from the temporal decorrelation correlation of fluid-phase angular velocity fluctuations at Eulerian grid (Ω′i/τr)e.
Retrograde condensation in natural porous media: An in situ experimental investigation
Authors: Igwe Uche , Khishvand Mahdi , Piri Mohammad
Published: January 2022

Complex in situ behavior of fluids during a retrograde condensation process is experimentally investigated in a miniature sandstone core sample. Two depletion experiments were conducted with various pressure decline rates using a three-component synthetic gas mixture with a dew point of 3610 psi. A state-of-the-art miniature core-flooding system integrated with a high-resolution micro-computed tomography scanner was employed to acquire pore-scale evidence of condensate nucleation, growth, accumulation, and mobilization in a natural porous medium under different depletion conditions. Analysis of pore-scale fluid occupancy maps demonstrates the formation of discrete nuclei of the condensate in pore throats and crevices as the pressure drops slightly below the dew point. The in situ fluid configurations show that a greater pressure drawdown rate significantly increases the condensate growth and accumulation. The results also illustrate the occurrence of condensate-to-gas imbibition displacements, i.e., snap-off and piston-like events, and the consequent trapping of the gas phase in the pore space. As the pore pressure is reduced, the condensate droplets are found to connect to each other through wetting layers, whereas the large gas clusters are continuously fragmented into smaller globules with reduced hydraulic connectivities. This effect was more pronounced in the case of the high depletion rate experiment. Furthermore, the condensate banking was not completely eliminated (through evaporation) by re-injecting the gas phase. This implies that in the development of a gas condensate reservoir, condensate dropout and banking should be minimized in the first place by, for instance, producing at lower pressure drawdown rates.
Ferroelectric-HfO2/oxide interfaces, oxygen distribution effects, and implications for device performance
Authors: Zhao Shihui , Li Bowen , Guo Yuzheng , Li Huanglong
Published: January 2022

Atomic-scale understanding of HfO2 ferroelectricity is important to help address many challenges in developing reliable and high-performance ferroelectric HfO2 (fe-HfO2) based devices. Though investigated from different angles, a factor that is real device-relevant and clearly deserves more attention has largely been overlooked by previous research, namely, the fe-HfO2/dielectric interface. Here, we investigate the electronic structures of several typical interfaces formed between ultrathin fe-HfO2 and oxide dielectrics in the sub-3-nm region. We find that interface formation introduces strong depolarizing fields in fe-HfO2, which is detrimental for ferroelectric polarization but can be a merit if tamed for tunneling devices, as recently demonstrated. Asymmetric oxygen distribution-induced polarity, intertwined with ferroelectric polarization or not, is also investigated as a relevant interfacial effect in the real device. Though considered detrimental from certain aspects, such as inducing build-in field (independent of ferroelectric polarization) and exacerbating depolarization (intertwined with ferroelectric polarization), it can be partly balanced out by other effects, such as annealing (extrinsic) and polarity-induced defect formation (intrinsic). This work provides insights into ferroelectric-HfO2/dielectric interfaces and some useful implications for the development of devices.
Adiabatic projection: Bridging ab initio, density functional, semiempirical, and embedding approximations
Authors: Janesko Benjamin G.
Published: January 2022

Modern electronic structure approximations routinely employ reference systems described by approximate Hamiltonians. This work introduces the adiabatic projection formalism for building formally exact corrections to such reference systems. Starting from the real Hamiltonian of a many-electron system, one constructs a reference system Hamiltonian by projecting the kinetic and electron–electron interaction operators onto “interesting” states. The reference system is corrected by density functionals for the difference between the projected and unprojected kinetic and electron–electron energies. These density functionals are constructed from adiabatic connections between the reference and real systems. The Hohenberg–Kohn theorems imply the existence of exact functionals, which can ensure that the reference system’s ground-state energy and density match the real system. Adiabatic projection further generalizes Kohn–Sham density functional theory (DFT) and the generalized adiabatic connection [W. Yang, J. Chem. Phys. 109, 10107 (1998)] and recovers these methods for certain choices of projection operators. Other choices of projection operators offer new opportunities, including formally exact and systematically improvable analogues to wavefunction-in-DFT embedding, DFT+U, and semiempirical theories. Numerical results are presented for two representative choices: a projected exchange–correlation correction to small-basis-set coupled cluster theory and a projected kinetic energy density functional correcting basis set errors in DFT. The latter offers performance for dimerization energies approaching the Boys–Bernardi counterpoise correction while also correcting intramolecular basis set superposition errors.
Using silicon disk resonators to measure mechanical losses caused by an electric field
Authors: Klochkov Y. Yu. , Prokhorov L. G. , Matiushechkina M. S. , Adhikari R. X. , Mitrofanov V. P.
Published: January 2022

Several projects of the next generation gravitational-wave detectors use the high purity monocrystalline silicon test masses. The electric field of the actuator that is applied to correct the position of the silicon test mass causes additional mechanical losses and associated noise. Disk mechanical resonators are widely used to study mechanical losses in multilayer optical coatings that are deposited on the test masses of gravitational-wave detectors. We use silicon disk resonators to study losses caused by an electric field. In particular, the dependence of mechanical losses on the resistivity of silicon is investigated. The resonator is a thin commercial silicon wafer in which a low frequency nodal diameter mode is excited. A DC voltage is applied between the wafer and a nearby electrode. We use two measurement configurations. In the first configuration, the dependence of losses on the resistance in the voltage supply circuit is investigated. The dependence of losses on the resistivity of silicon is investigated in the second configuration. We propose a model that relates the electric field induced mechanical loss in disk resonators to the resistivity of the material. Measurements are carried out for low and high resistivity silicon wafers. The measurement results are compared with calculations. Based on these studies, it is possible to estimate the loss and noise of the test masses of gravitational-wave detectors associated with electrostatic actuators.
Amplification of pulsed light with arbitrary frequency chirps on nanosecond timescales
Authors: Clarke B. S. , Gould P. L.
Published: January 2022

We have developed a system for producing amplified pulses of frequency-chirped light at 780 nm on nanosecond timescales. The system starts with tunable cw laser light and employs a pair of fiber-based phase modulators, a semiconductor optical amplifier, and a tapered amplifier to achieve chirp rates exceeding 3 GHz/10 ns and peak powers greater than 1 W. Driving the modulators with an arbitrary waveform generator enables arbitrary chirp shapes, such as two-frequency linear chirps. We overcome the optical power limitations of the modulators by duty cycling and avoid unseeded operation of the tapered amplifier by multiplexing the chirped pulses with “dummy” light from a separate diode laser.
Acoustic ring resonator: Experiments and simulations
Authors: Robertson William M. , Vazquez Carina , LaVerde Alexander , Wassenberg Austin , Olson Colleen , Lopez Jennifer
Published: January 2022

The application of acoustic ring resonator structures for the manipulation of audio frequency acoustic waves is demonstrated experimentally and via numerical simulation. Three ring resonator systems are demonstrated: a simple single ring structure that acts as a comb/notch filter, a single ring between two parallel waveguides that acts as an add-drop filter, and a sequential array of equally spaced rings that creates acoustic bandgaps. The experiments are conducted in linear waveguides using an impulse response method. The ring resonators were created via 3D printing. Finite element numerical simulations were conducted using COMSOL.
Global well-posedness and decay estimates to the 3D Cauchy problem of nonhomogeneous magneto-micropolar fluid equations with vacuum
Authors: Yang Xinying , Zhong Xin
Published: January 2022

We investigate a model of nonhomogeneous magneto-micropolar fluids in the whole three-dimensional space R3. Under the assumption that the initial energy is suitably small, we prove the global existence and decay estimates of strong solutions. Moreover, there is no need to impose some compatibility condition on the initial data via time weighted techniques although the system under consideration degenerates near vacuum. Our analysis is based on delicate energy estimates and the structural characteristics of the model.
Overload performance study and fabrication of the capacitive pressure-sensitive chip with linkage film
Authors: Chuai Rongyan , Yang Yuxin , Zhang Bing , Jiang Guimin , Zhang He
Published: January 2022

In order to satisfy the demands of pressure measurement under high overload conditions, the overload characteristics of the capacitive pressure-sensitive chip with linkage film are studied. Through the simulation and analysis for the stress distribution of this sensitive structure and in light of the dimension effect of the tensile strength of monocrystalline silicon, the influence of sizes of the sensitive structure on the overload pressure is expounded. The simulated results illustrate that the maximum overload pressure can exceed 200 times the full-scale (FS) when appropriately adjusting the sizes of the sensitive structure. The proposed chip is fabricated using SOI wafers combined with bonding technology. Our experimental results show that the sample chip has a linear response in the pressure range of 25–100 kPa, and its overload pressure is 4.5 MPa, reaching 45 times the full-scale.
Electrical transport properties of atomically thin WSe2 using perpendicular magnetic anisotropy metal contacts
Authors: Gupta S. , Ohshima R. , Ando Y. , Endo T. , Miyata Y. , Shiraishi M.
Published: January 2022

Tungsten diselenide, WSe2, shows excellent properties and becomes a very promising material among two-dimensional semiconductors. Wide bandgap and large spin–orbit coupling along with naturally lacking inversion symmetry in the monolayer WSe2 make it an efficient material for spintronics, optoelectronics, and valleytronics applications. In this work, we report electrical transport properties of a monolayer WSe2 based field effect transistor with most needed multilayer Co/Pt ferromagnetic electrodes exhibiting perpendicular magnetic anisotropy. We studied contact behavior by performing I-V curve measurements and estimating Schottky barrier heights (SBHs). SBHs estimated from experimental data are found to be comparatively small without using any tunnel barrier. This work expands the current understanding of WSe2 based devices and gives insight into the electrical behavior of Co/Pt metal contacts, which can open great possibilities for spintronic/valleytronic applications.
Dynamical phenomena connected with stability loss of equilibria and periodic trajectories
Authors: Neishtadt A. I. , Treschev D. V.
Published: January 2022

This is a study of a dynamical system depending on a parameter

. Under the assumption that the system has a family of equilibrium positions or periodic trajectories smoothly depending on

, the focus is on details of stability loss through various bifurcations (Poincaré–Andronov– Hopf, period-doubling, and so on). Two basic formulations of the problem are considered. In the first,

is constant and the subject of the analysis is the phenomenon of a soft or hard loss of stability. In the second,

varies slowly with time (the case of a dynamic bifurcation). In the simplest situation

, where

is a small parameter. More generally,

may be a solution of a slow differential equation. In the case of a dynamic bifurcation the analysis is mainly focused around the phenomenon of stability loss delay.

Bibliography: 88 titles.
One-dimensional dynamical systems
Authors: Efremova L. S. , Makhrova E. N.
Published: January 2022

The survey is devoted to the topological dynamics of maps defined on one-dimensional continua such as a closed interval, a circle, finite graphs (for instance, finite trees), or dendrites (locally connected continua without subsets homeomorphic to a circle). Connections between the periodic behaviour of trajectories, the existence of a horseshoe and homoclinic trajectories, and the positivity of topological entropy are investigated. Necessary and sufficient conditions for entropy chaos in continuous maps of an interval, a circle, or a finite graph, and sufficient conditions for entropy chaos in continuous maps of dendrites are presented. Reasons for similarities and differences between the properties of maps defined on the continua under consideration are analyzed. Extensions of Sharkovsky’s theorem to certain discontinuous maps of a line or an interval and continuous maps on a plane are considered.

Bibliography: 207 titles.
Unlocking adults’ implicit statistical learning by cognitive depletion
Authors: Smalle Eleonore H. M. , Daikoku Tatsuya , Szmalec Arnaud , Duyck Wouter , Möttönen Riikka
Published: January 2022

Significance

Statistical learning mechanisms enable extraction of patterns in the environment from infancy to adulthood. For example, they enable segmentation of continuous speech streams into novel words. Adults typically become aware of the hidden words even when passively listening to speech streams. It remains poorly understood how cognitive development and brain maturation affect implicit statistical learning (i.e., infant-like learning without awareness). Here, we show that the depletion of the cognitive control system by noninvasive brain stimulation or by demanding cognitive tasks boosts adults’ implicit but not explicit word-segmentation abilities. These findings suggest that the adult cognitive architecture constrains statistical learning mechanisms that are likely to contribute to early language acquisition and opens avenues to enhance language-learning abilities in adults.
WUSCHEL-related homeobox
family genes in rice control lateral root primordium size
Authors: Kawai Tsubasa , Shibata Kyosuke , Akahoshi Ryosuke , Nishiuchi Shunsaku , Takahashi Hirokazu , Nakazono Mikio , Kojima Takaaki , Nosaka-Takahashi Misuzu , Sato Yutaka , Toyoda Atsushi , Lucob-Agustin Nonawin , Kano-Nakata Mana , Suralta Roel R. , Niones Jonathan M. , Chen Yinglong , Siddique Kadambot H. M. , Yamauchi Akira , Inukai Yoshiaki
Published: January 2022

Significance

In recent years, phenotypic plasticity has received attention for improving plant adaptability to variable environments. For more than half a century, it has been known that rice and cereal plants develop different types of lateral roots (LRs), unlike the dicot model plant
Arabidopsis
. Despite the importance of plastic LR development under variable water conditions, the molecular mechanisms regulating LR types are unknown. Here, we report the regulatory mechanism of LR primordium size in rice, an important determinant of LR type. We identified two
WUSCHEL
-related homeobox (WOX) transcription factors that opposingly regulate LR primordium size. Our findings form the basis for improving root phenotypic plasticity for sustainable crop production under variable environments.
A neural surveyor to map touch on the body
Authors: Miller Luke E. , Fabio Cécile , Azaroual Malika , Muret Dollyane , van Beers Robert J. , Farnè Alessandro , Medendorp W. Pieter
Published: January 2022

Significance

Perhaps the most recognizable “sensory map” in neuroscience is the somatosensory homunculus. Although the homunculus suggests a direct link between cortical territory and body part, the relationship is actually ambiguous without a decoder that knows this mapping. How the somatosensory system derives a spatial code from an activation in the homunculus is a longstanding mystery we aimed to solve. We propose that touch location is disambiguated using multilateration, a computation used by surveying and global positioning systems to localize objects. We develop a Bayesian formulation of multilateration, which we implement in a neural network to identify its computational signature. We then detect this signature in psychophysical experiments. Our results suggest that multilateration provides the homunculus-to-body mapping necessary for localizing touch.
Sector search strategies for odor trail tracking
Authors: Reddy Gautam , Shraiman Boris I. , Vergassola Massimo
Published: January 2022

Significance

Surface-bound odor trail tracking is critical for the survival of terrestrial animals dependent on olfaction. Little is known about how animals track trails at the algorithmic level. In the present study, we propose that a tracking animal maintains a noisy estimate of where the trail is headed based on its past contacts with the trail. We show that virtual agents trained to exploit this strategy reproduce the tracking patterns of ants and rodents. The observed patterns emerge simply as a consequence of common geometric constraints, which also impose fundamental limits on how quickly an animal can track trails. A series of experiments is proposed to quantify how past experience and trail statistics shape tracking behavior.
Trawl impacts on the relative status of biotic communities of seabed sedimentary habitats in 24 regions worldwide
Authors: Pitcher C. Roland , Hiddink Jan G. , Jennings Simon , Collie Jeremy , Parma Ana M. , Amoroso Ricardo , Mazor Tessa , Sciberras Marija , McConnaughey Robert A. , Rijnsdorp Adriaan D. , Kaiser Michel J. , Suuronen Petri , Hilborn Ray
Published: January 2022

Significance

We estimated the biological state of seabed sedimentary habitats, with specified uncertainty, in 24 trawled regions worldwide. Seabed status differed greatly among regions (from 0.25 to 0.999, relative to an untrawled state of 1); 15 regions had average status > 0.9. Two-thirds of all assessed seabed area was untrawled with status = 1, 93% had status > 0.8, but 1.5% had status = 0. The total area swept by trawling was a strong driver of regional status, providing a relationship to predict status from the regional estimated total amount of trawling. Seabed status is high in regions where fisheries are exploited sustainably—emphasizing that good fishery management contributes to better ecosystem outcomes—and, conversely, low status highlights regions needing improved management.
Structural basis for effector recognition by an antibacterial type IV secretion system
Authors: Oka Gabriel U. , Souza Diorge P. , Cenens William , Matsuyama Bruno Y. , Cardoso Marcus V. C. , Oliveira Luciana C. , da Silva Lima Filipe , Cuccovia Iolanda M. , Guzzo Cristiane R. , Salinas Roberto K. , Farah Chuck S.
Published: January 2022

Significance

Type IV secretion systems (T4SSs) have been studied for more than 70 y because of their roles in mediating horizontal DNA transfer, responsible for the spread of antibiotic resistance, and the injection of virulence factors into animal and plant hosts. Another important function is the contact-dependent injection of toxic effectors into competing bacteria of different species during bacterial warfare. The present study reveals how T4SSs use a specific domain of the VirD4 coupling protein to recruit antibacterial toxins for secretion by recognizing conserved carboxyl-terminal secretion signal domains. The molecular structure of the secretion signal domain described in this work will serve as a model for thousands of homologs encountered in several hundred distinct bacterial species.
Proteomics of isolated sieve tubes fromNicotiana tabacum: sieve element–specific proteins reveal differentiation of the endomembrane system
Authors: Liu Yan , Vasina Viktoriya V. , Kraner Max E. , Peters Winfried S. , Sonnewald Uwe , Knoblauch Michael
Published: January 2022

Significance

Sieve elements are crucially important plant cells that distribute photoassimilates and communicate developmental and defensive signals throughout the plant body. They remain the least understood cell type in plants nonetheless, defying standard research methods as they are exceedingly sensitive and possess neither nucleus (no DNA) nor protein synthesis. We developed a protocol to isolate sieve elements for proteome analysis and discovered unfamiliar sieve element–specific proteins that define an internal differation of the endoplasmic reticulum—which demonstrates the power of this approach to the elusive sieve element.
Submicron drops from flapping bursting bubbles
Authors: Jiang Xinghua , Rotily Lucas , Villermaux Emmanuel , Wang Xiaofei
Published: January 2022

Significance

Bubble bursting aerosols play a critical role in forming clouds, scattering sunlight, and transporting pathogens from water to the air. Most of them are produced from the fragmentation of bubble cap film. They usually have a diameter below 1 μm. However, their physical production mechanism has remained unknown. In this work, we discovered that these drops are probably generated from flapping bubble cap film (like a flapping flag). It explains the mysterious relation between bubble size and number of drops produced per bubble, providing a fundamental framework for understanding the production flux of bubble bursting aerosols, such as sea spray aerosol, and substance transfer through the air–water interface during drop ejection.
Evidence that Pacific tuna mercury levels are driven by marine methylmercury production and anthropogenic inputs
Authors: Médieu Anaïs , Point David , Itai Takaaki , Angot Hélène , Buchanan Pearse J. , Allain Valérie , Fuller Leanne , Griffiths Shane , Gillikin David P. , Sonke Jeroen E. , Heimbürger-Boavida Lars-Eric , Desgranges Marie-Maëlle , Menkes Christophe E. , Madigan Daniel J. , Brosset Pablo , Gauthier Olivier , Tagliabue Alessandro , Bopp Laurent , Verheyden Anouk , Lorrain Anne
Published: January 2022

Significance

Humans are exposed to toxic methylmercury mainly by consuming marine fish. New environmental policies under the Minamata Convention rely on a yet-poorly-known understanding of how mercury emissions translate into fish methylmercury levels. Here, we provide the first detailed map of mercury concentrations from skipjack tuna across the Pacific. Our study shows that the natural functioning of the global ocean has an important influence on tuna mercury concentrations, specifically in relation to the depth at which methylmercury concentrations peak in the water column. However, mercury inputs originating from anthropogenic sources are also detectable, leading to enhanced tuna mercury levels in the northwestern Pacific Ocean that cannot be explained solely by oceanic processes.
Machine learning–driven multiscale modeling reveals lipid-dependent dynamics of RAS signaling proteins
Authors: Ingólfsson Helgi I. , Neale Chris , Carpenter Timothy S. , Shrestha Rebika , López Cesar A. , Tran Timothy H. , Oppelstrup Tomas , Bhatia Harsh , Stanton Liam G. , Zhang Xiaohua , Sundram Shiv , Di Natale Francesco , Agarwal Animesh , Dharuman Gautham , Kokkila Schumacher Sara I. L. , Turbyville Thomas , Gulten Gulcin , Van Que N. , Goswami Debanjan , Jean-Francois Frantz , Agamasu Constance , Chen De , Hettige Jeevapani J. , Travers Timothy , Sarkar Sumantra , Surh Michael P. , Yang Yue , Moody Adam , Liu Shusen , Van Essen Brian C. , Voter Arthur F. , Ramanathan Arvind , Hengartner Nicolas W. , Simanshu Dhirendra K. , Stephen Andrew G. , Bremer Peer-Timo , Gnanakaran S. , Glosli James N. , Lightstone Felice C. , McCormick Frank , Nissley Dwight V. , Streitz Frederick H.
Published: January 2022

Significance

Here we present an unprecedented multiscale simulation platform that enables modeling, hypothesis generation, and discovery across biologically relevant length and time scales to predict mechanisms that can be tested experimentally. We demonstrate that our predictive simulation-experimental validation loop generates accurate insights into RAS-membrane biology. Evaluating over 100,000 correlated simulations, we show that RAS–lipid interactions are dynamic and evolving, resulting in: 1) a reordering and selection of lipid domains in realistic eight-lipid bilayers, 2) clustering of RAS into multimers correlating with specific lipid fingerprints, 3) changes in the orientation of the RAS G-domain impacting its ability to interact with effectors, and 4) demonstration that RAS–RAS G-domain interfaces are nonspecific in these putative signaling domains.
North American tree migration paced by climate in the West, lagging in the East
Authors: Sharma Shubhi , Andrus Robert , Bergeron Yves , Bogdziewicz Michal , Bragg Don C. , Brockway Dale , Cleavitt Natalie L. , Courbaud Benoit , Das Adrian J. , Dietze Michael , Fahey Timothy J. , Franklin Jerry F. , Gilbert Gregory S. , Greenberg Cathryn H. , Guo Qinfeng , Hille Ris Lambers Janneke , Ibanez Ines , Johnstone Jill F. , Kilner Christopher L. , Knops Johannes M. H. , Koenig Walter D. , Kunstler Georges , LaMontagne Jalene M. , Macias Diana , Moran Emily , Myers Jonathan A. , Parmenter Robert , Pearse Ian S. , Poulton-Kamakura Renata , Redmond Miranda D. , Reid Chantal D. , Rodman Kyle C. , Scher C. Lane , Schlesinger William H. , Steele Michael A. , Stephenson Nathan L. , Swenson Jennifer J. , Swift Margaret , Veblen Thomas T. , Whipple Amy V. , Whitham Thomas G. , Wion Andreas P. , Woodall Christopher W. , Zlotin Roman , Clark James S.
Published: January 2022

Significance

Suitable habitats for forest trees may be shifting fast with recent climate change. Studies tracking the shift in suitable habitat for forests have been inconclusive, in part because responses in tree fecundity and seedling establishment can diverge. Analysis of both components at a continental scale reveals a poleward migration of northern species that is in progress now. Recruitment and fecundity both contribute to poleward spread in the West, while fecundity limits spread in the East, despite a fecundity hotspot in the Southeast. Fecundity limitation on population spread can confront conservation and management efforts with persistent disequilibrium between forest diversity and rapid climate change.