bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of high precision wavelength calibration method for plasmas rotation measurement based on Fabry–Pérot etalon on experimental advanced superconducting tokamak
Authors: Fu Shengyu , Yin Xianghui , Fu Jia , Li Yingying , Wang Fudi , Zhang Hongming , Bae Cheonho , Lyu Bo , Huang Qianhong , Shen Yongcai , Li Yichao , He Liang , Jin Yifei , Gong Xueyu
Published: April 2022

Analyzing the radiation spectra of impurity ions is a widely applied diagnostic scheme for plasma ion temperature and rotation measurements on tokamaks. High precision wavelength calibration is a prerequisite for the accurate measurement of plasma parameters, especially for plasma rotation. Furthermore, the sparseness or absence of the standard spectral lines brings calibration challenges due to the narrow wavelength range. A precise wavelength calibration method is demonstrated in which the comb-like spectra generated by the Fabry–Pérot etalon can lock a series of fixed peaks as reference points in a wide wavelength range. The equal frequency intervals of the comb-like spectra are further corrected using several characteristic neon lines of known wavelengths. The experimental results indicate that the wavelength accuracy obtained by this calibration method is less than 0.005 nm, which corresponds to a rotation speed of 2.3 km/s in the toroidal direction for the beam emission spectroscopy spectrometer installed on the experimental advanced superconducting tokamak. Taking the O V(650.024 nm, n = 4 → 3) line as an example, the maximum difference in the oxygen ion rotation velocity is 3.8 km/s for the absolute rotation of ∼25 km/s, when compared with the calibration results of a standard lamp.
Dispersion of particles in two-dimensional monopolar and dipolar vortices using a Lagrangian stochastic model
Authors: Ocampo Jaimes J. , Graef F. , Zavala Sansón L.
Published: April 2022

The dispersion of particles in two-dimensional vortices, two circular monopoles, and the Chaplygin–Lamb dipole is studied numerically with a Lagrangian stochastic model. The monopoles are the Rankine and the steady Oseen vortex, whose azimuthal velocity profile is irrotational at a long radial distance. The total velocity of each particle is divided into two parts: the deterministic field due to the vortex plus a stochastic velocity representing homogeneous turbulence. The experiments are carried out with thousands of particles to calculate the dispersion as a function of time. The dispersion in the monopoles grows rapidly and then increases at a lower rate as the particles transit toward the potential region. This transition occurs more quickly in the Rankine vortex, so the Oseen vortex has a wider time-lapse to generate a more significant dispersion. In the case of the Chaplygin–Lamb dipole, having an internal and external flow, the dispersion has different behavior depending on which region the particles depart. The dispersion curves describe the exchange of particles between the poles and the outer flow as the dipole drifts. We discuss the capacity of the dipole to transport particles through long distances.
Thermal transpiration flows induced by differences in accommodation coefficients
Authors: Sugimoto Shogo , Sugimoto Hiroshi
Published: April 2022

The behavior of a rarefied gas between two parallel plates, each having its uniform temperature but having a square wave-like distribution of the accommodation coefficients, is numerically analyzed using the Direct Simulation Monte Carlo method. The gas temperature near the plate becomes close to the plate temperature only if the accommodation coefficient of the wall is large enough. A lower accommodation coefficient leads to the difference between the gas temperature and the adjacent wall. This temperature distribution induces a gas flow similar to the well-known thermal transpiration flow along the plate. When only one plate has a wave-like distribution of the accommodation coefficients, an array of vortical flow is induced between the plates. The magnitude of the vortex is linear to the difference in the accommodation coefficients. When both plates have a wave-like distribution of the accommodation coefficients, a one-way flow through the channel between the plates is induced. This flow depends on the phase difference of the discontinuity point. The size of one-way flow is nonlinear to the difference in accommodation coefficients.
A novel square planar N42− ring with aromaticity in BeN4
Authors: Lin Jiani , Wang Fangxu , Rui Qi , Li Jianfu , Wang Qinglin , Wang Xiaoli
Published: April 2022

A structural search leads to the prediction of a novel alkaline earth nitride BeN4 containing a square planar N42− ring. This compound has a particular chemical bonding pattern giving it potential as a high-energy-density material. The P4/nmm phase of BeN4 may be stable under ambient conditions, with a bandgap of 3.72 eV. It is predicted to have high thermodynamic and kinetic stability due to transfer of the outer-shell s electrons of the Be atom to the N4 cluster, with the outer-shell 2p orbital accommodating the lone-pair electrons of N42−. The total of six π electrons is the most striking feature, indicating that the square planar N42− exhibits aromaticity. Under ambient conditions, BeN4 has a high energy density (3.924 kJ/g relative to Be3N2 and N2 gas), and its synthesis might be possible at pressures above 31.6 GPa.
Freezing point depression of salt aqueous solutions using the Madrid-2019 model
Authors: Lamas Cintia P. , Vega Carlos , Noya Eva G.
Published: April 2022

Salt aqueous solutions are relevant in many fields, ranging from biological systems to seawater. Thus, the availability of a force-field that is able to reproduce the thermodynamic and dynamic behavior of salt aqueous solutions would be of great interest. Unfortunately, this has been proven challenging, and most of the existing force-fields fail to reproduce much of their behavior. In particular, the diffusion of water or the salt solubility are often not well reproduced by most of the existing force-fields. Recently, the Madrid-2019 model was proposed, and it was shown that this force-field, which uses the TIP4P/2005 model for water and non-integer charges for the ions, provides a good description of a large number of properties, including the solution densities, viscosities, and the diffusion of water. In this work, we assess the performance of this force-field on the evaluation of the freezing point depression. Although the freezing point depression is a colligative property that at low salt concentrations depends solely on properties of pure water, a good model for the electrolytes is needed to accurately predict the freezing point depression at moderate and high salt concentrations. The coexistence line between ice and several salt aqueous solutions (NaCl, KCl, LiCl, MgCl2, and Li2SO4) up to the eutectic point is estimated from direct coexistence molecular dynamics simulations. Our results show that this force-field reproduces fairly well the experimentally measured freezing point depression with respect to pure water freezing for all the salts and at all the compositions considered.
Structure of octonionic Hilbert spaces with applications in the Parseval equality and Cayley–Dickson algebras
Authors: Huo Qinghai , Ren Guangbin
Published: April 2022

Contrary to the simple structure of the tensor product of the quaternionic Hilbert space, the octonionic situation becomes more involved. It turns out that an octonionic Hilbert space can be decomposed as an orthogonal direct sum of two subspaces, each of them isomorphic to a tensor product of an irreducible octonionic Hilbert space with a real Hilbert space. As an application, we find that for a given orthogonal basis, the octonionic Parseval equality holds if and only if the basis is weak associative. Fortunately, there always exists a weak associative orthogonal basis in an octonionic Hilbert space. This completely removes the obstacles caused by the failure of the octonionic Parseval equality.
Widom insertion method in simulations with Ewald summation
Authors: Bakhshandeh Amin , Levin Yan
Published: April 2022

We discuss the application of the Widom insertion method for calculation of the chemical potential of individual ions in computer simulations with Ewald summation. Two approaches are considered. In the first approach, an individual ion is inserted into a periodically replicated overall charge neutral system representing an electrolyte solution. In the second approach, an inserted ion is also periodically replicated, leading to the violation of the overall charge neutrality. This requires the introduction of an additional neutralizing background. We find that the second approach leads to a much better agreement with the results of grand canonical Monte Carlo simulation for the total chemical potential of a neutral ionic cluster.
Contagion–diffusion processes with recurrent mobility patterns of distinguishable agents
Authors: Valgañón P. , Soriano-Paños D. , Arenas A. , Gómez-Gardeñes J.
Published: April 2022

The analysis of contagion–diffusion processes in metapopulations is a powerful theoretical tool to study how mobility influences the spread of communicable diseases. Nevertheless, many metapopulation approaches use indistinguishable agents to alleviate analytical difficulties. Here, we address the impact that recurrent mobility patterns, and the spatial distribution of distinguishable agents, have on the unfolding of epidemics in large urban areas. We incorporate the distinguishable nature of agents regarding both their residence and their usual destination. The proposed model allows both a fast computation of the spatiotemporal pattern of the epidemic trajectory and the analytical calculation of the epidemic threshold. This threshold is found as the spectral radius of a mixing matrix encapsulating the residential distribution and the specific commuting patterns of agents. We prove that the simplification of indistinguishable individuals overestimates the value of the epidemic threshold.
Recovery in the wake of in-line axial-flow rotors
Authors: Posa A. , Broglia R. , Balaras E.
Published: April 2022

The flow around the rotor of an axial turbine, operating in the wake of an upstream one, is resolved using large-eddy simulation on a cylindrical grid consisting of 3.8 billion points. Three distances from the upstream rotor are considered, ranging from 6 to 10 diameters. The inflow boundary conditions for the simulation of the downstream rotor were generated by a precursor simulation of the upstream one. The impact on the dynamics of the tip vortices and the statistics at their core is compared across cases. Results demonstrate the strong sensitivity of the tip vortices shed by the downstream rotor to the disturbance produced by the wake of the upstream one. The onset of their instability moves very close to the rotor plane and is almost independent of the distance between the upstream and downstream rotors, at least in the range of simulated distances. This makes the development of the wake of the downstream rotors, driven by the instability of the tip vortices, much faster and very similar across distances from the upstream one. The results explain the phenomena of performance stabilization of downstream turbines in linear arrays, recently reported in the literature.
Engineered near- and far-field optical response of dielectric nanostructures using focused cylindrical vector beams
Authors: Montagnac M. , Agez G. , Patoux A. , Arbouet A. , Paillard V.
Published: April 2022

Near- and far-field optical properties of silicon nanostructures under linear polarization (Gaussian beam) and azimuthally or radially focused cylindrical vector beams are investigated by finite-difference time-domain method (FDTD) in Meep open-source software. A python toolkit allowing FDTD simulations in Meep for using those excitation sources is provided. In addition to the preferential excitation of specific electric or magnetic resonance modes as a function of the excitation beam polarization, it is shown in the case of spheroids that shape anisotropy affects the resonance wavelength and the dipole orientation of the magnetic or electric dipole mode. Depending on the spheroid symmetry axis with respect to the electric field orientation, the electric dipole resonance can be split into two peaks, giving quasi-unidirectional scattering, separated by an anapole mode. The optical properties in both far-field (scattering pattern) and near-field (electric and magnetic field hot spots) can be tuned by changing the excitation polarization at a fixed wavelength and selecting properly the spheroid shape and dimensions. These numerical simulations are extended to top-down fabrication-friendly nanostructures such as nanocylinders with circular or elliptic sections.
Droplet coalescence by molecular dynamics and phase-field modeling
Authors: Heinen Matthias , Hoffmann Marco , Diewald Felix , Seckler Steffen , Langenbach Kai , Vrabec Jadran
Published: April 2022

Coalescence of argon droplets with a radius of 25, 50, and 100 nm is studied with computational methods. Molecular dynamics (MD) simulations are carried out to generate reference data. Moreover, a phase-field model resting on a Helmholtz energy equation of state is devised and evaluated by computational fluid dynamics (CFD) simulations. Exactly the same scenarios in terms of geometry, fluid, and state are considered with these approaches. The MD and CFD simulation results show an excellent agreement over the entire coalescence process, including the decay of the inertia-induced oscillation of the merged droplet. Theoretical knowledge about the asymptotic behavior of coalescence process regimes is confirmed. All considered scenarios cross from the inertially limited viscous regime over to the inertial regime because of the low shear viscosity of argon. The particularly rapid dynamics during the initial stages of the coalescence process in the thermal regime is also captured by the phase-field model, where a closer look at the liquid density reveals that metastable states associated with negative pressure are attained in the emerging liquid bridge between the coalescing droplets. This demonstrates that this model is even capable of adequately handling the onset of coalescence. To speed up CFD simulations, the phase-field model is transferred to coarser grids through an interface widening approach that retains the thermodynamic properties including the surface tension.
Orbits of charged particles trapped in a dipole magnetic field
Authors: Liu Rong , Liu Siming , Zhu Fengrong , Chen Qihui , He Yu , Cai Chengmiao
Published: April 2022

Motion of a test charged particle in a dipole magnetic field can be reduced to a two degree-of-freedom Hamiltonian system due to the axisymmetry of the dipole field. We carried out a systematic study of orbits of low-energy trapped charged particles in the dipole field via calculation of their Lyapunov characteristic exponents (LCEs) with random initial conditions in the four-dimensional phase space. Since there is at most one positive LCE, these orbits are classified as chaotic ones with one positive LCE and quasi-periodic ones with vanishing LCEs. The dependence of the fraction of quasi-periodic orbits in the phase space on the particle energy is given, which reveals a discrete spectrum, confirming the results of earlier studies. It is also found that most quasi-periodic orbits are confined near the equatorial plane and away from the dipole except for some at very low energies, while chaotic ones are ergodic. The distribution of the maximum LCE (mLCE) appears to vary gradually in the phase space and chaotic orbits with very low values of the mLCE wander near quasi-periodic orbits for a significant amount of time before merging into the sea of chaos.
Effect of interfacial kinetics on the settling of a drop in a viscous medium
Authors: Jadhav Sayali N. , Ghosh Uddipta
Published: April 2022

Multiphase emulsions, such as drops in a continuous medium, tend to have surfactant-like impurities present at the interfaces, either naturally or introduced artificially for stability, which may influence the flow field and, hence, alter the motion of the drops through a host of different mechanisms. Here, we carry out a robust analysis to characterize multiple aspects of such interfacial phenomena by studying the settling of a drop in a quiescent viscous medium. The surface active agents are assumed to be bulk-insoluble and non-ideal, while the interface itself is assumed to have its own rheology, described by the Boussinesq–Scriven model. The diffusive fluxes of the surfactants are expressed in a thermodynamically consistent manner as proportional to the chemical potential gradient, which results in concentration dependent diffusivity. We subsequently derive semi-analytical solutions for approximately spherical drops without any other restrictions on the transport processes. Our results reveal that stresses originating from interfacial rheology tend to decrease the settling velocity and at the same time make the surfactant concentration uniform across the surface. Remarkably, this settling velocity is revealed to be independent of the choice of the free-energy isotherms and the extent of packing of the surfactants when a variable diffusivity is correctly accounted for. These insights will be helpful in better understanding of the underlying dynamics of surfactant-laden drops, having potential applications in microfluidic devices, food and pharmaceutical industries, and separation processes.
Study and characterization of GaN MOS capacitors: Planar vs trench topographies
Authors: Mukherjee K. , De Santi C. , You S. , Geens K. , Borga M. , Decoutere S. , Bakeroot B. , Diehle P. , Altmann F. , Meneghesso G. , Zanoni E. , Meneghini M.
Published: April 2022

Developing high quality GaN/dielectric interfaces is a fundamental step for manufacturing GaN vertical power transistors. In this paper, we quantitatively investigate the effect of planar etching treatment and trench formation on the performance of GaN-based MOS (metal oxide semiconductor) stacks. The results demonstrate that (i) blanket etching the GaN surface does not degrade the robustness of the deposited dielectric layer; (ii) the addition of the trench etch, while improving reproducibility, results in a decrease in the breakdown performance compared to the planar structures. (iii) For trench structures, the voltage for a 10 year lifetime is still above 20 V, indicating a good robustness. (iv) To review the trapping performance across the metal-dielectric-GaN stack, forward-reverse capacitance–voltage measurements with and without stress and photo-assistance are performed. Overall, as-grown planar capacitors devoid of prior etching steps show the lowest trapping, while trench capacitors have higher interface trapping and bulk trapping comparable to the blanket etched capacitors. (v) The nanostructure of the GaN/dielectric interface was characterized by high resolution scanning transmission electron microscopy. An increased roughness of 2–3 monolayers at the GaN surface was observed after blanket etching, which was correlated with the higher density of interface traps. The results presented in this paper give fundamental insight on how the etch and trench processing affects the trapping and robustness of trench-gate GaN-metal-oxide-semiconductor field effect transistors and provide guidance for the optimization of device performance.
Connecting dynamic pore filling mechanisms with equilibrium and out of equilibrium configurations of fluids in nanopores
Authors: Kikkinides E. S. , Gkogkos G. , Monson P. A. , Valiullin R.
Published: April 2022

In the present study, using dynamic mean field theory complemented by grand canonical molecular dynamics simulations, we investigate the extent to which the density distributions encountered during the dynamics of capillary condensation are related to those distributions at equilibrium or metastable equilibrium in a system at fixed average density (canonical ensemble). We find that the states encountered can be categorized as out of equilibrium or quasi-equilibrium based on the magnitude of the driving force for mass transfer. More specifically, in open-ended slit pores, pore filling via double bridging is an out of equilibrium process, induced by the dynamics of the system, while pore filling by single bridge formation is connected to a series of configurations that are equilibrium configurations in the canonical ensemble and that cannot be observed experimentally by a standard adsorption process, corresponding to the grand canonical ensemble. Likewise, in closed cap slits, the formation of a liquid bridge near the pore opening and its subsequent growth while the initially detached meniscus from the capped end remains immobilized are out of equilibrium processes that occur at large driving forces. On the other hand, at small driving forces, there is a continuous acceleration of the detached meniscus from the capped end, which is associated with complete reversibility in the limit of an infinitesimally small driving force.
Enhancement of damping-like field and field-free switching in Co/Pt bilayer films through quantitative engineering of anisotropy gradient
Authors: Fan Haodong , Luo Yongming , Wu Birui , Xu Xiuyuan , Zhuang Yanshan , Feng Zhongshu , Li Wenjun , Zhou Tiejun
Published: April 2022

Spin–orbit torque (SOT) is an emerging candidate for electrically controlled magnetization switching in low-power and nonvolatile spintronic devices. However, SOT switching of perpendicular magnetization requires an auxiliary field or additional lateral symmetry breaking, which is difficult to achieve in practical applications. In particular, the mechanism of field-free switching through vertical symmetry breaking still lacks a quantitative description. In this work, a vertically asymmetric Co/Pt bilayer has been constructed through quantitative engineering of anisotropy gradient, while keeping the total magnetic thickness of the bilayer constant. Interestingly, the enhanced asymmetry with greater anisotropy gradient would induce higher SOT efficiencies and larger field-free switching ratios. Field-free switching can be attributed to the slight lateral asymmetry caused by the perpendicular anisotropy gradient. The SOT effective-field enhancement and field-free switching through quantitative engineering of the anisotropy gradient not only offer a deeper understanding of current-induced magnetization switching in perpendicularly asymmetric systems but also provide a potential avenue for practical applications of SOT devices at the wafer level.
Metamorphoses and explosively remote synchronization in dynamical networks
Authors: Long Yong-Shang , Zhai Zheng-Meng , Tang Ming , Lai Ying-Cheng
Published: April 2022

We uncover a phenomenon in coupled nonlinear networks with a symmetry: as a bifurcation parameter changes through a critical value, synchronization among a subset of nodes can deteriorate abruptly, and, simultaneously, perfect synchronization emerges suddenly among a different subset of nodes that are not directly connected. This is a synchronization metamorphosis leading to an explosive transition to remote synchronization. The finding demonstrates that an explosive onset of synchrony and remote synchronization, two phenomena that have been studied separately, can arise in the same system due to symmetry, providing another proof that the interplay between nonlinear dynamics and symmetry can lead to a surprising phenomenon in physical systems.
The effects of caudal fin's bending stiffness on a self-propelled carangiform swimmer
Authors: Wu Buchen , Shu Chang , Lee HsuChew , Wan Minping
Published: April 2022

The hydrodynamic performance of a self-propelled carangiform swimmer with a flexible caudal fin in the absence of a free stream is numerically investigated, where the fin's dimensionless bending stiffness varies from 10−3 to 150. It reveals that large flexibility of the caudal fin has a negative impact on the propulsion and moderate rigidity is found to increase the hydrodynamic performance. Two different vortex configurations are observed at low and high bending stiffnesses: (i) reverse Bénard–von Kármán (rBvK) vortex configuration and (ii) deflected reverse Bénard–von Kármán wake with the secondary vortex street, respectively. With the increase in bending stiffness, the thrust-producing part switches from the swimmer body to the caudal fin corresponding to the switch of the vortex configuration. Furthermore, the thrust and drag productions are examined. As the bending stiffness increases, the “active portion” of the caudal fin provides more kinetic energy to the wake flow. It is found that the deflected rBvK is induced by the vortical strength imbalance of two adjacent vortices, and the secondary vortex street is formed by the large strain between the primary vortex and the secondary vortex street. Meanwhile, the dynamic mode decomposition analysis indicates that the dominant mode of the dynamic flow field is the excited frequency resonant mode and the inherent frequency of the secondary vortex street is the same as the undulatory frequency. These results shed new light onto the role of the flexible caudal fin in self-propelled biological systems and may provide some inspirations to autonomous underwater vehicle design.
Research progress on photoacoustic SF6 decomposition gas sensor in gas-insulated switchgear
Authors: Yin Xukun , Su Yongliang , Xi Teli , Chen Baisong , Zhang Le , Zhang Xueshi , Liu Lixian , Shao Xiaopeng
Published: April 2022

In the power industry, sulfur hexafluoride (SF6) as an insulating gas is widely used in gas-insulated switchgears (GISs). Owing to the latent inner insulation defects of GIS, various SF6 gas decompositions are generated in the process of partial superheating and partial discharge (PD). The decomposition components and concentrations are different under different PD types. A number of gas sensors were reported for the detection of these decompositions. Photoacoustic spectroscopy (PAS) gas sensors have been developed for many applications owing to their high sensitivity and selectivity, such as gas pollutant detection, industrial process control, and non-invasive medical diagnosis. Due to the SF6 physical constants being different from that of nitrogen (N2) or air, the sensor structure should be redesigned. A detailed review of four different types of PAS-based gas sensors is discussed and compared.
Review of Scientific Instruments New Products
Authors: Mandelis Andreas
Published: April 2022

In order to supplement manufacturers’ information, this department will welcome the submission by our readers of brief communications reporting measurements on the physical properties of materials, which supersede earlier data or suggest new research applications.
Voyage of Whale and Calf
Authors: Pirotta Vanessa , Metcalfe Samantha
Published: April 2022

Calf is a newborn humpback whale, venturing into an exciting marine world while being nurtured and cared for by his mother. Join them as they travel along the east coast of Australia, meeting marine creatures. See the challenges Calf and Whale face as they head down into the icy waters of Antarctica, and marvel at these amazing ocean giants.

The Voyage of Whale and Calf explores humpback whale migration – plunge below the surface to learn more about the lives of these magnificent marine mammals!

Reading level varies from child to child, but we recommend this book for ages 6 to 9.
Physical constraints on thermoregulation and flight drive morphological evolution in bats
Authors: Rubalcaba Juan G. , Gouveia Sidney F. , Villalobos Fabricio , Cruz-Neto Ariovaldo P. , Castro Mario G. , Amado Talita F. , Martinez Pablo A. , Navas Carlos A. , Dobrovolski Ricardo , Diniz-Filho José Alexandre Felizola , Olalla-Tárraga Miguel Á.
Published: April 2022

Significance

Energetic constraints of flight and thermoregulation have long been thought to explain why most bat species are small and live predominantly in warm latitudes. We use physical models to investigate how body size, wing shape, and climate modulate these energetic constraints. Our model predicts that thermoregulatory and flight costs, respectively, impose upper and lower bounds on the wing surface-to-mass ratio, giving rise to an optimum shape, and that variations around this optimum are more constrained in cold regions. A comparative analysis across bat species supports the model’s predictions, suggesting that body shape evolves toward an optimum with stronger selective pressures in cold regions. The model and data together suggest that thermoregulatory and locomotory constraints modulate the evolution of bats’ morphology.
Long-term monitoring reveals widespread and severe declines of understory birds in a protected Neotropical forest
Authors: Pollock Henry S. , Toms Judith D. , Tarwater Corey E. , Benson Thomas J. , Karr James R. , Brawn Jeffrey D.
Published: April 2022

Significance

We leveraged a 44-y population study of Neotropical understory birds from a protected forest reserve in central Panama to document widespread and severe declines in bird abundance. Our findings provide evidence that tropical bird populations may be undergoing systematic declines, even in relatively intact forests. The implications of these findings are that biodiversity baselines may be shifting over time, and large tracts of tropical forest may not be sufficient for maintaining stable bird populations. Our study highlights the importance of long-term monitoring for detecting cryptic losses in biodiversity and motivates the need for future work drilling down to the underlying mechanisms to understand and mitigate future declines.
Single cell enhancer activity distinguishes GABAergic and cholinergic lineages in embryonic mouse basal ganglia
Authors: Su-Feher Linda , Rubin Anna N. , Silberberg Shanni N. , Catta-Preta Rinaldo , Lim Kenneth J. , Ypsilanti Athena R. , Zdilar Iva , McGinnis Christopher S. , McKinsey Gabriel L. , Rubino Thomas E. , Hawrylycz Michael J. , Thompson Carol , Gartner Zev J. , Puelles Luis , Zeng Hongkui , Rubenstein John L. R. , Nord Alex S.
Published: April 2022

Significance

During brain development, neurons are generated by spatially and temporally distinct processes that remain to be fully characterized. The ganglionic eminences (GEs) in the embryonic subpallium give rise to GABAergic and cholinergic neuron lineages that form the basal ganglia or migrate to the cerebral cortex. Beyond a limited set of canonical RNA markers, the transcriptional states of GE progenitors and immature neurons cells remain poorly defined. We combine enhancer labeling, single-cell transcriptomics using transcription factor-anchored clustering, and integration with in situ hybridization data to distinguish emerging neuronal populations in embryonic mouse basal ganglia. Our results demonstrate the specificity of enhancer-based labeling at single-cell resolution and reveal developmental origins and specification processes of critical neuronal lineages.
Computational mechanisms for context-based behavioral interventions: A large-scale analysis
Authors: Zhao Wenjia Joyce , Coady Aoife , Bhatia Sudeep
Published: April 2022

Significance

A large body of research in the social and behavioral sciences studies the impact of behavioral interventions (or “nudges”) on decisions. Although this work has been extremely influential, we currently lack an overarching theoretical framework for behavioral interventions that provides a systematic account of their behavioral consequences, cognitive and neurobiological mechanisms, and statistical interpretations. In this paper, we propose such a theoretical framework using the diffusion decision model, a quantitative theory of decision-making whose parameters offer a theoretically compelling characterization of choice underpinnings. Our results not only reveal insights about how context-based interventions alter behavior but also offer practitioners a model-based method for choosing between behavioral interventions based on different goals.
Helical self-assembly of a mucin segment suggests an evolutionary origin for von Willebrand factor tubules
Authors: Javitt Gabriel , Fass Deborah
Published: April 2022

Significance

Extracellular proteins with mechanical functions often require specialized assembly processes to form covalent oligomers. Progress in tissue bioengineering and repair will benefit from an understanding of how to harness and manipulate these processes. Here, we show that a particular supramolecular assembly mode was pre-encoded in the ancient domain organization common to gel-forming mucins and von Willebrand factor, glycoproteins that are deceptively different due to their divergence for distinct mechanical tasks. This finding highlights symmetry principles and building blocks retooled in nature to construct polymers with wide-ranging properties. These building blocks and knowledge of their self-assembly can be used to design new polymeric structures.
Social experiences switch states of memory engrams through regulating hippocampal Rac1 activity
Authors: Lei Bo , Lv Li , Hu Shiqiang , Tang Yikai , Zhong Yi
Published: April 2022

Significance

It is well known that silent memory engrams in pathological or artificial conditions can be artificially switched into the latent state for retrieval by natural recall cues. Thus, physiological strategies that depend on the underlying molecular mechanisms for switching between silent state and latent state are a subject for investigation. Here, we show that social experiences stimulated switching between latent and silent engrams to achieve flexible memory accessibility and also reveal the basic molecular mechanism of: 1) social reward turning silent engram to latent via suppression of Rac1 activity in CA1 neurons of the hippocampus; and 2) social stress switching latent memory engram into silent through activating Rac1. Together, this work demonstrates emotion-driven bidirectional switching between latent and silent engrams.
Infrastructure inequality is a characteristic of urbanization
Authors: Pandey Bhartendu , Brelsford Christa , Seto Karen C.
Published: April 2022

Significance

We find that urban infrastructure inequalities are a characteristic feature of urbanization, with multiscale patterns that highlight greater inequalities at regional than at local intracity scales. Results show that the level of urban infrastructure inequality has a significant bearing on urbanization characteristics. Owing to infrastructure inequalities, urbanization as a pathway to sustainable development faces fundamental constraints. Our study raises intriguing questions about the urban infrastructure inequality implications of future urbanization and the spatial scales at which we ought to understand and address these inequalities.
Wolbachia
depletion blocks transmission of lymphatic filariasis by preventing chitinase-dependent parasite exsheathment
Authors: Quek Shannon , Cook Darren A. N. , Wu Yang , Marriott Amy E. , Steven Andrew , Johnston Kelly L. , Ford Louise , Archer John , Hemingway Janet , Ward Stephen A. , Wagstaff Simon C. , Turner Joseph D. , Taylor Mark J.
Published: April 2022

Significance

Lymphatic filariasis caused by
Wuchereria bancrofti
,
Brugia malayi
, and
Brugia timori
affects 51 million people, leading to severe physical and mental disabilities. A mutualistic symbiosis between these filarial nematodes and
Wolbachia
bacteria has been exploited as a new curative treatment. Epidemiological modeling of anti-
Wolbachia
treatment assumes that transmission persists due to the lag phase before microfilariae (mf) become removed from circulation. Here, we show that
Wolbachia
-depleted mf cannot develop within the mosquito vector—a phenotype associated with down-regulation of
B. malayi
mf-specific chitinase, an enzyme essential for exsheathment. Our findings add to the broad range of host biological processes dependent on
Wolbachia
and suggest that anti-
Wolbachia
treatment mediates a more accelerated impact on elimination of lymphatic filariasis than currently predicted.
GPCR large-amplitude dynamics by
19
F-NMR of aprepitant bound to the neurokinin 1 receptor
Authors: Pan Benxun , Liu Dongsheng , Yang Lingyun , Wüthrich Kurt
Published: April 2022

Significance

G protein-coupled receptor (GPCR) structures determined by X-ray crystallography or cryo-electron microscopy include 28 receptors for which complexes with agonists and antagonists can be compared. In all these comparisons, an interatomic distance representing the size of the orthosteric ligand binding groove differs by less than 2.9 Å. In this report,
19
F-NMR observations of the NK1R-bound drug molecule aprepitant show that the orthosteric binding groove undergoes transient fluctuations with amplitudes 6 to 8 Å. We propose that this large-amplitude plasticity enables a multistep selection of functional ligands with variable efficacies. These insights into structural dynamics also provide a rationale for the observation that diffracting crystals are obtained for GPCR complexes with only few of the ligands that bind to the receptors.
Chinmo
is the larval member of the molecular trinity that directs
Drosophila
metamorphosis
Authors: Truman James W. , Riddiford Lynn M.
Published: April 2022

Significance

The genome of insects with complete metamorphosis contains the instructions for making three distinct body forms, that of the larva, of the pupa, and of the adult. However, the molecular mechanisms by which each gene set is called forth and stably expressed are poorly understood. A half century ago, it was proposed that there was a set of three master genes that inhibited each other’s expression and enabled the expression of genes for each respective stage. We show that the transcription factor
chinmo
is essential for maintaining the larval stage in
Drosophila
, and with two other regulatory genes,
broad
and
E93
, makes up the trinity of mutually repressive master genes that underlie insect metamorphosis.
A touch-based multimodal and cryptographic bio-human–machine interface
Authors: Lin Shuyu , Zhu Jialun , Yu Wenzhuo , Wang Bo , Sabet Kiarash A. , Zhao Yichao , Cheng Xuanbing , Hojaiji Hannaneh , Lin Haisong , Tan Jiawei , Milla Carlos , Davis Ronald W. , Emaminejad Sam
Published: April 2022

Significance

The awareness of the individuals’ biological status is critical for creating interactive environments. Accordingly, we devised a multimodal cryptographic bio-human–machine interface (CB-HMI), which seamlessly translates touch-based entries into encrypted biochemical, biophysical, and biometric indices (i.e., circulating biomarkers levels, heart rate, oxygen saturation level, and fingerprint pattern). As its central component, the CB-HMI features thin hydrogel-coated chemical sensors and a signal interpretation framework to access/interpret biochemical indices, bypassing the challenge of circulating analyte accessibility and the confounding effect of pressing force variability. Upgrading the surrounding objects with CB-HMI, we demonstrated new interactive solutions for driving safety and medication use, where the integrated CB-HMI uniquely enabled one-touch bioauthentication (based on the user’s biological state/identity), prior to rendering the intended services.
Towards a sociology of consuming translated fiction
Authors: Tekgül-Akın Duygu
Published: April 2022

This article aims to explore British readers’ aesthetic responses to fiction in translation, based on ethnographic data from reading groups around the UK. Examining excerpts from book club meetings on Haruki Murakami’sAfter Dark(trans. Jay Rubin), Ivan Turgenev’sFathers and Sons(trans. Richard Freeborn) and José Eduardo Agualusa’sRainy Season(trans. Daniel Hahn), the study investigates judgements regarding the visibility of translation in particular. A case is made for “consuming” translated literature. With an analytical perspective derived from the sociology of art, the paper focuses on the various dimensions of reading such as pleasure, status and textual-linguistic (in)tolerance. The analysis of excerpts reveals that readers derive pleasure from texts that have undergone interlingual transfer as long as they recognize the artistry involved in the translation profession, where such recognition is culture-bound.
Estimating one’s own environmental impact: others, acceptability and offsetting (Estimando el propio impacto ambiental: los demás, lo aceptable y lo compensable)
Authors: Pasca Laura
Published: April 2022

Despite people’s concern for the environment, there are psychological barriers that make it difficult to adopt a pro-environmental lifestyle, including difficulties in estimating the environmental impact of behaviours. In a first study ( n = 374), we see that, when estimating the environmental impact of our own behaviours, we believe that pro-environmental actions can offset the environmental impact of those that are harmful to the environment. In addition, we believe that others have a greater impact. A second study ( n = 497) finds that people who believe they have a lower impact on the environment than others and less than should be deemed acceptable display less intent to behave pro-environmentally. These findings highlight the difficulty people face in knowing the environmental consequences of their own behaviour, as well as the importance of perceptions regarding others’ behaviours in explaining the intent to behave pro-environmentally.
Filament organization of the bacterial actin MreB is dependent on the nucleotide state
Authors: Pande Vani , Mitra Nivedita , Bagde Saket Rahul , Srinivasan Ramanujam , Gayathri Pananghat
Published: April 2022

MreB, the bacterial ancestor of eukaryotic actin, is responsible for shape in most rod-shaped bacteria. Despite belonging to the actin family, the relevance of nucleotide-driven polymerization dynamics for MreB function is unclear. Here, we provide insights into the effect of nucleotide state on membrane binding of Spiroplasma citri MreB5 (ScMreB5). Filaments of ScMreB5WT and an ATPase-deficient mutant, ScMreB5E134A, assemble independently of the nucleotide state. However, capture of the filament dynamics revealed that efficient filament formation and organization through lateral interactions are affected in ScMreB5E134A. Hence, the catalytic glutamate functions as a switch, (a) by sensing the ATP-bound state for filament assembly and (b) by assisting hydrolysis, thereby potentially triggering disassembly, as observed in other actins. Glu134 mutation and the bound nucleotide exhibit an allosteric effect on membrane binding, as observed from the differential liposome binding. We suggest that the conserved ATP-dependent polymerization and disassembly upon ATP hydrolysis among actins has been repurposed in MreBs for modulating filament organization on the membrane.
Applications of the close-limit approximation: horizonless compact objects and scalar fields
Authors: Annulli Lorenzo , Cardoso Vitor , Gualtieri Leonardo
Published: April 2022

The ability to model the evolution of compact binaries from the inspiral to coalescence is central to gravitational wave astronomy. Current waveform catalogues are built from vacuum binary black hole models, by evolving Einstein equations numerically and complementing them with knowledge from slow-motion expansions. Much less is known about the coalescence process in the presence of matter, or in theories other than general relativity. Here, we explore the close limit approximation as a powerful tool to understand the coalescence process in general setups. In particular, we study the head-on collision of two equal-mass, compact but horizonless objects. Our results show the appearance of ‘echoes’ and indicate that a significant fraction of the merger energy goes into these late-time repetitions. We also apply the close limit approximation to investigate the effect of colliding black holes on surrounding scalar fields. Notably, our results indicate that observables obtained through perturbation theory may be extended to a significant segment of the merger phase, where in principle only a numerical approach is appropriate.
Enhancing laser-nanoparticle interactions by diffused laser beams: efficient size-reduction of nanoparticles
Authors: Zheng Xinyue , Ando Kota , Wang Xiaolong , Sakka Tetsuo , Nakajima Takashi
Published: April 2022

Generally speaking, a laser beam with a good spatial profile such as flat-top or Gaussian (TEM00 mode) shape is considered to be a prerequisite to maximize laser-matter interactions. On the contrary, we show that if the process of interest has a threshold in terms of laser fluence or intensity, a diffused laser beam can do a good job of inducing the process. As an example, we demonstrate the efficient size-reduction of colloidal nanoparticles by a diffused laser beam and identify that the physical origin of this counterintuitive results is a redistribution of laser energy, i.e. formation of speckles through a diffuser where the local laser fluence exceeds the size-reduction threshold. We report the systematic results for silver and gold nanoparticles.
First-principles study of direct band gap semiconductors XS2 (X = Zr and Hf) with orthorhombic symmetry
Authors: Zhang Ruotong , Fang Yimei , Wu Fulun , Cao Xinrui , Zhou Yinghui , Zhu Zi-Zhong , Wu Shunqing
Published: April 2022

Transition metal dichalcogenides have attracted intense interest due to their potential applications as electronic and optical devices. Here, we propose two XS2 (X = Zr and Hf) compounds within the orthorhombic Pnma phase, denoted as Pnma-ZrS2 and Pnma-HfS2, as promising candidates for thin-film solar cells and nanoelectronics. Both Pnma-ZrS2 and Pnma-HfS2 are found to be semiconductors with desired direct band gaps of 1.07 and 1.24 eV, respectively, which lead to large visible-light absorption. The absorption coefficients of the first absorption peak for the Pnma-XS2 are about two times larger than the corresponding one for the P

3
ˉ

m1 phase with a 1T-CdI2-like structure. Such Pnma-XS2 polymorphs are predicted to be mechanically, dynamically, and thermodynamically stable up to 500 K, and they are highly realizable in experiments since a phase transition from the P

3
ˉ

m1 phases to the Pnma phases could occur under moderate temperatures, based on our calculations.
Wireless transmission of voltage transients from a chronically implanted neural stimulation device
Authors: Frederick Rebecca A , Troyk Philip R , Cogan Stuart F
Published: April 2022

Objective. Consistent transmission of data from wireless neural devices is critical for monitoring the condition and performance of stimulation electrodes. To date, no wireless neural interface has demonstrated the ability to monitor the integrity of chronically implanted electrodes through wireless data transmission. Approach. In this work, we present a method for wirelessly recording the voltage transient (VT) response to constant-current, cathodic-first asymmetric pulsing from a microelectrode array. We implanted six wireless devices in rat sciatic nerve and wirelessly recorded VT measurements throughout a 38 week implantation period. Main results. Electrode maximum cathodic potential excursion (Emc), access voltage, and driving voltage (extracted from each VT) remained stable throughout the 38 week study period. Average Emc (from an applied +0.6 V interpulse bias) in response to 4.7 µA, 200.2 µs pulses was 267 ± 107 mV at week 1 post-implantation and 282 ± 52 mV at week 38 post-implantation. Access voltage for the same 4.7 µA pulsing amplitude was 239 ± 65 mV at week 1 post-implantation and 268 ± 139 mV at week 38 post-implantation. Significance. The VT response recorded via reverse telemetry from the wireless microelectrode array did not significantly change over a 38 week implantation period and was similar to previously reported VTs from wired microelectrodes with the same geometry. Additionally, the VT response recorded wirelessly in phosphate buffered saline before and after device implantation appeared as expected, showing significantly less electrode polarization and smaller access voltage than the VT response in vivo.