bluuebunny/crossref_metadata_2025 huggingface dataset:
Precision measurements in the beta decay of 6He
Authors: Kanafani Mohamad , Fléchard Xavier , Naviliat-Cuncic Oscar , Chung Gyang Davou , Leblond Sylvain , Liénard Etienne , Mougeot Xavier , Quéméner Gilles , Simancas Di Filippo Adriana , Thomas Jean-Charles
Published: April 2023

We report here about the ongoing data analysis of an experiment performed at GANIL with a 25 keV 6He+ beam to determine the Fierz interference term from the β particles energy spectrum.
Status of the COMET experiment
Authors: Jansen Andreas
Published: April 2023

The COMET (COherent Muon to Electron Transition) experiment, currently being built in Tokai, Japan, will search for the coherent neutrinoless transition of muons to electrons in the coulomb field of atomic nuclei. The process is highly suppressed in the Standard Model and therefore provides a promising channel to probe new physics. The experiment will be carried out in a staged approach. Phase-I of COMET aims to search for the process with a single event sensitivity of 𝒪(10−15). Additionally, precise measurements of muon beam dynamics and detector prototyping for Phase-II will be conducted. Utilizing a much higher intensity proton beam, a more complex and longer muon/electron transport system, and gained experience from Phase-I, an improvement of at least four orders of magnitude over the current best branching ratio limit up to 𝒪(10−17) is envisioned for Phase-II. This article will give a status report for Phase-I of COMET.
Psychosoziale Betreuung früh verwaister Eltern – Eine
quantitative Querschnittsstudie an deutschen
Entbindungsstationen
Authors: Ingrisch Silke , Berth Hendrik , Schulze Wolfram
Published: April 2023

Einleitung Das Versterben des Säuglings kurz nach der Geburt
stellt eine massive psychische Belastung für die betroffenen Eltern dar.
Die Verfügbarkeit einer empathischen geburtshilflichen Betreuung ist
daher ein wichtiger Beitrag zur Prävention von Folgeerkrankungen.

Ziel Ziel der Studie ist es, die aktuellen Vorgehensweisen der
psychosozialen Betreuung von Eltern bei einem perinatalen Kindstod in deutschen
Kliniken zu erheben. Es werden die Zusammenhänge zwischen
Klinikgröße und Anzahl an Informationsangebote für die
Eltern und zwischen Unterstützungsangeboten für das
Klinikpersonal und Anzahl der Informations-angebote für trauernde Eltern
eruiert. In einer quantitativen Querschnittsstudie in Form einer Vollerhebung
wurden an 206 deutschen Kliniken mit Entbindungsstation Fachpersonen mittels
Fragenbogen befragt. Die Auswertung der Daten erfolgte mittels
Regressionsanalyse.

Ergebnisse 206 Klinken haben an der Befragung teilgenommen. Die Analysen
bestätigten: Die Größe der Klinik hat einen hoch
signifikant positiven Effekt auf die Anzahl der Angebote für trauernde
Eltern. Die Anzahl der Angebote für das Klinikpersonal wirkt sich hoch
signifikant positiv auf die Anzahl der Informationsangebote für
trauernde Eltern aus.

Schlussfolgerungen Handlungsempfehlungen aus dieser Studie sind: dem
Klinikpersonal spezielle Fortbildungen zum Thema perinatalen Kindstods anbieten,
die Ärzt*innen-Patient*in-Beziehung durch Balint- oder
Supervisionsgruppen stärken, die interne und externe
interdisziplinäre Zusammenarbeit fördern.
What isn’t public health?
Authors: Brookfield Samuel
Published: April 2023

By recognizing the structural causes of health and illness, public health has often been associated with values of compassion and solidarity, and a relational understanding of human agency. Rather than supporting the consistent integration and application of these insights, however, public health is now sometimes invoked more as a rhetorical move, used to construct issues as simple questions of neoliberal scientistic rationalism. Public health practitioners must reckon, therefore, with how the field can be discursively deployed in the public square, for multiple divergent political ends. If public health is always positioned as a value-neutral and detached scientific approach to addressing complex subjects, from drug use to pandemics, it not only fails to connect with the arguments of its critics, but further divorces what was once called the public health ‘movement’ from the strong and progressive political and theoretical positions it was founded upon and should advocate for today.
Commutators on Fock spaces
Authors: Alpay Daniel , Cerejeiras Paula , Kähler Uwe , Kling Trevor
Published: April 2023

Given a weighted ℓ2 space with weights associated with an entire function, we consider pairs of weighted shift operators, whose commutators are diagonal operators, when considered as operators over a general Fock space. We establish a calculus for the algebra of these commutators and apply it to the general case of Gelfond–Leontiev derivatives. This general class of operators includes many known examples, such as classic fractional derivatives and Dunkl operators. This allows us to establish a general framework, which goes beyond the classic Weyl–Heisenberg algebra. Concrete examples for its application are provided.
Novel non-Joule heating technique: Externally laser-heated diamond anvil cell
Authors: Okuda Yoshiyuki , Oka Kenta , Hikosaka Koutaro , Hirose Kei
Published: April 2023

The externally heated diamond anvil cell (EHDAC) conducts high pressure and temperature experiments with spatial uniformity and temporal stability. These are conventionally combined with various spectroscopies and x-ray diffraction measurements. EHDAC techniques perform Joule heating on a heater placed close to or directly in contact with diamond anvils. However, the electrical wiring and heater required for Joule heating complicate EHDAC setups, hindering easy access for the measurement of physical properties. This study proposes an EHDAC technique using laser- instead of Joule-heating. We successfully achieved temperatures reaching 900 K by applying heat to diamond anvils through laser-heating of the gaskets with thermally insulating anvil seats. To test this setup, we measured the melting temperature of H2O ice VII, which was consistent with previous studies. We also measured the high-pressure and temperature impedance of H2O VII and verified the capability of electrical resistivity measurements in this setup. This technique allows various physical property measurements owing to its simple setup required for externally laser-heated diamond anvil cell experiments. The unique characteristics of this heating technique are that (1) no heaters or wiring are required, (2) it exhibits the most efficient heating among EHDAC studies, (3) it maintains the DAC body at room temperature, and (4) diamond anvils do not detach from anvil seats after the EHDAC experiment. This method significantly simplifies the experimental setup, which allows much easier access to various physical property measurements using an EHDAC.
Temperature-insensitive optical fiber strain sensor fabricated by two parallel connection Fabry–Perot interferometers with air-bubbles
Authors: Zhang Han , Jiang Chao , Hu Jin , Song Jiao , Zhu Xiping , Wang Pei , Li Hong
Published: April 2023

A strain sensor formed by a parallel connection of two Fabry–Perot interferometers (FPI) is proposed. The femtosecond laser is used to process a micro groove on the end face of a single-mode fiber (SMF), and then, it is welded with another SMF to form a small air bubble at the fusion point, fabricating an FPI. When the axial strain acts on the air bubble, the transverse length of the air bubble will change, causing the air cavity of the FPI to be easily deformed, and FPI can obtain high strain sensitivity. Three FPIs were manufactured with the air bubble sizes of 63, 78, and 93 µm, respectively, and the strain sensitivities of the three FPIs are 2.9, 2.0, and 1.5 pm/µε, respectively. The experimental results show that the smaller the air bubble, the higher the strain sensitivity of FPI. Since the free spectral ranges of the three FPIs are relatively similar, we, respectively, paralleled them to form two Vernier effect strain sensors, and their sensitivities are −14.9 and −14.5 pm/µε, respectively. Their sensitivities are increased by 5.1 times and 7.3 times, respectively. In addition, because three FPIs are composed of air cavities, they have very low temperature sensitivities. When they are connected in parallel, their resonance peak wavelength moves in the same direction with an increase in temperature, forming a reduced Vernier effect, and the temperature sensitivity amplification is very small. Therefore, the temperature cross-sensitivity of the sensor is extremely low and can be ignored.
Experiment with nitrogen seeding at the Globus-M2 tokamak
Authors: Vekshina E. , Dolgova K. , Rozhansky V. , Kaveeva E. , Senichenkov I. , Molchanov P. , Timokhin V. , Khromov N. , Zhiltsov N. , Bakharev N. , Kiselev E. , Tuhmeneva E.
Published: April 2023

First experiment with nitrogen seeding has been performed at the compact spherical tokamak Globus-M2. Significant reduction of the electron temperature and the energy flux to the outer lower divertor target has been observed experimentally and reproduced in the modeling with the SOLPS-ITER code.
An application of Heun functions in the quantum mechanics of a constrained particle
Authors: Schmidt Alexandre G. M. , Pereira Matheus E.
Published: April 2023

Using the thin-layer quantization, we formulate the problem of a Schrödinger particle constrained to move along a coordinate surface of the bi-spherical coordinate system. In three-dimensional space, the free Schrödinger equation is not separable in this coordinate system. However, when we consider the equation for a particle constrained to a given surface, there are only two degrees of freedom. One has to introduce a geometrical potential to attach the particle to the surface. This well-known potential has two contributions: one from Gauss’ curvature and the other from the mean curvature. The Schrödinger equation leads to a general Heun equation. We solve it exactly and present the eigenfunctions and plots of the probability densities, and, as an application of this methodology, we study the problem of an electric charge propagating along these coordinate surfaces in the presence of a uniform magnetic field.
Mean-field model of synchronization for open-loop, swirl controlled thermoacoustic system
Authors: Singh Samarjeet , Kumar Dutta Ankit , Dhadphale Jayesh M. , Roy Amitesh , Sujith R. I. , Chaudhuri Swetaprovo
Published: April 2023

Open-loop control is known to be an effective strategy for controlling self-excited periodic oscillations, known as thermoacoustic instability, in turbulent combustors. Here, we present experimental observations and a synchronization model for the suppression of thermoacoustic instability achieved by rotating the otherwise static swirler in a lab-scale turbulent combustor. Starting with the state of thermoacoustic instability in the combustor, we find that a progressive increase in the swirler rotation rate leads to a transition from the state of limit cycle oscillations to the low-amplitude aperiodic oscillations through a state of intermittency. To model such a transition while also quantifying the underlying synchronization characteristics, we extend the model of Dutta et al. [Phys. Rev. E 99, 032215 (2019)] by introducing a feedback between the ensemble of phase oscillators and the acoustic. The coupling strength in the model is determined by considering the effect of the acoustic and swirl frequencies. The link between the model and experimental results is quantitatively established by implementing an optimization algorithm for model parameter estimation. We show that the model is capable of replicating the bifurcation characteristics, nonlinear features of time series, probability density function, and amplitude spectrum of acoustic pressure and heat release rate fluctuations at various dynamical states observed during the transition to the state of suppression. Most importantly, we discuss the flame dynamics and demonstrate that the model without any spatial inputs qualitatively captures the characteristics of the spatiotemporal synchronization between the local heat release rate fluctuations and the acoustic pressure that underpins a transition to the state of suppression. As a result, the model emerges as a powerful tool for explaining and controlling instabilities in thermoacoustic and other extended fluid dynamical systems, where spatiotemporal interactions lead to rich dynamical phenomena.
Ray-based cross-beam energy transfer modeling for broadband lasers
Authors: Follett R. K. , Colaïtis A. , Seaton A. G. , Wen H. , Turnbull D. , Froula D. H. , Palastro J. P.
Published: April 2023

Broadband lasers have the potential to mitigate cross-beam energy transfer (CBET) in direct-drive inertial confinement fusion (ICF) experiments. A quantitative assessment of the bandwidth required for CBET mitigation necessitates the development of broadband ray-based CBET models that can be implemented in the radiation-hydrodynamic codes that are used to design ICF experiments. Two different approaches to broadband ray-based CBET modeling (discrete and fixed spectrum) are developed and compared to wave-based calculations. Both approaches give good agreement with wave-based calculations in ICF-relevant configurations. Full-scale 3D calculations show that the bandwidth required for adequate CBET mitigation increases with increasing scale and drive intensity.
A Kr*–Rb cold collision apparatus based on atom trap
Authors: Liu Si-Yu , Wang Yu-Chan , Wu Rui-Fan , Yang Guo-Min , Jiang Wei
Published: April 2023

A cold collision between atoms and molecules (<1 K) is one of the hot research fields in atomic and molecular physics. At low temperatures, the number of partial waves participating in the collision process decreases dramatically, and quantum phenomena start to emerge. The reaction is often dominated by quantum tunneling, and pronounced resonances can exist on collision cross sections. Here, we report on an apparatus designed for studying cold collisions between metastable noble gas atoms and alkali atoms. Our apparatus features a combined Magneto-Optical-Trap (MOT) and velocity map imaging (VMI) system. The center of a Rb MOT is overlapped with the VMI system. Cold Kr* atoms are launched toward the Rb atoms to induce Kr* + Rb reactions. The collision energy between the two species can be varied from 100 mK to 20 K. With this setup, we are planning to explore the quantum phenomena in Kr* + Rb cold collisions, including the shape resonance and stereodynamics in the reaction.
Addressable microfluidics technology for non-sacrificial analysis of biomaterial implants in vivo
Authors: Nguyen Minh , Tong Anh , Volosov Mark , Madhavarapu Shreya , Freeman Joseph , Voronov Roman
Published: April 2023

Tissue regeneration-promoting and drug-eluting biomaterials are commonly implanted into animals as a part of late-stage testing before committing to human trials required by the government. Because the trials are very expensive (e.g., they can cost over a billion U.S. dollars), it is critical for companies to have the best possible characterization of the materials' safety and efficacy before it goes into a human. However, the conventional approaches to biomaterial evaluation necessitate sacrificial analysis (i.e., euthanizing a different animal for measuring each time point and retrieving the implant for histological analysis), due to the inability to monitor how the host tissues respond to the presence of the material in situ. This is expensive, inaccurate, discontinuous, and unethical. In contrast, our manuscript presents a novel microfluidic platform potentially capable of performing non-disruptive fluid manipulations within the spatial constraints of an 8 mm diameter critical calvarial defect—a “gold standard” model for testing engineered bone tissue scaffolds in living animals. In particular, here, addressable microfluidic plumbing is specifically adapted for the in vivo implantation into a simulated rat's skull, and is integrated with a combinatorial multiplexer for a better scaling of many time points and/or biological signal measurements. The collected samples (modeled as food dyes for proof of concept) are then transported, stored, and analyzed ex vivo, which adds previously-unavailable ease and flexibility. Furthermore, care is taken to maintain a fluid equilibrium in the simulated animal's head during the sampling to avoid damage to the host and to the implant. Ultimately, future implantation protocols and technology improvements are envisioned toward the end of the manuscript. Although the bone tissue engineering application was chosen as a proof of concept, with further work, the technology is potentially versatile enough for other in vivo sampling applications. Hence, the successful outcomes of its advancement should benefit companies developing, testing, and producing vaccines and drugs by accelerating the translation of advanced cell culturing tech to the clinical market. Moreover, the nondestructive monitoring of the in vivo environment can lower animal experiment costs and provide data-gathering continuity superior to the conventional destructive analysis. Lastly, the reduction of sacrifices stemming from the use of this technology would make future animal experiments more ethical.
Electromechanical resonances and field-emission-induced self-oscillations of single crystal diamond needles
Authors: Kleshch Victor I. , Ismagilov Rinat R. , Mukhin Vsevolod V. , Orekhov Anton S. , Poncharal Philippe , Purcell Stephen T. , Obraztsov Alexander N.
Published: April 2023

Due to its outstanding mechanical characteristics, diamond is an ideal material for use in micro- and nano-electromechanical systems. In this paper, we report on the investigation of vibrational properties of singly clamped needlelike diamond microcrystallites with nanoscale tips. The single-crystal diamond needles were produced by selective oxidation of polycrystalline films grown using chemical vapor deposition. The study of resonant oscillations driven by the AC voltage indicated that the elastic modulus of such diamond needles is close to that of bulk single crystal diamond. A self-oscillation regime induced by the DC voltage during field emission from the apex of a diamond needle is also demonstrated. It is shown that this regime can be used for efficient DC–AC conversion in microdevices. The high structural quality of diamond needles, their remarkable mechanical properties, and the relative ease of their mass fabrication make them promising candidates for application in various electromechanical systems, field-emission devices, and scanning probe techniques.
Evaluation of space charge distribution under a divergent electric field by combining experiment and simulation
Authors: He Penglong , Liu Yuxin , Zhang Bo , He Jinliang
Published: April 2023

Under divergent electric fields, space charge is locally accumulated and controls the initiation and evolution of insulation degradation phenomena, such as electrical trees and partial discharge. The space charge profiles provide crucial information for evaluating the insulation performance. However, the existing space charge measurement methods are not directly applicable under divergent electric fields. In this paper, a method combining experiment and simulation is proposed to evaluate the space charge distribution around a needle electrode. An experimental system is established, and the acoustic waves are measured with a hydrophone placed on the symmetric axis. In order to obtain the space charge distribution, the space charge injection process is simulated using the bipolar charge transport model to reduce the freedom of the distribution. Then, calculations are made for the acoustic waves produced by the simulated space charge distributions. Using the signals without the contribution of internal charge, a correspondence between the experiment and simulation is established. For each experimental signal, the matched calculated signal is obtained using the zero-crossing time as a reference. A perfect match between them is presented after the amplitude compensation, which indicates that the space charge distribution in the experiment is identical to that in the simulation model.
Propagating wave merging in a precipitation reaction
Authors: Ahmed Boshir , Mersing David , Tinsley Mark R. , Showalter Kenneth
Published: April 2023

Propagating precipitation waves are a remarkable form of spatiotemporal behavior that arise through the coupling of reaction, diffusion, and precipitation. We study a system with a sodium hydroxide outer electrolyte and an aluminum hydroxide inner electrolyte. In a redissolution Liesegang system, a single propagating precipitation band moves down through the gel, with precipitate formed at the band front and precipitate dissolved at the band back. Complex spatiotemporal waves occur within the propagating precipitation band, including counter-rotating spiral waves, target patterns, and annihilation of waves on collision. We have also carried out experiments in thin slices of gel, which have revealed propagating waves of a diagonal precipitation feature within the primary precipitation band. These waves display a wave merging phenomenon in which two horizontally propagating waves merge into a single wave. Computational modeling permits the development of a detailed understanding of the complex dynamical behavior.
Lyapunov exponents of multi-state cellular automata
Authors: Vispoel M. , Daly A. J. , Baetens J. M.
Published: April 2023

In order to describe the sensitivity of a cellular automaton (CA) to a small change in its initial configuration, one can attempt to extend the notion of Lyapunov exponents as defined for continuous dynamical systems to a CA. So far, such attempts have been limited to a CA with two states. This poses a significant limitation on their applicability, as many CA-based models rely on three or more states. In this paper, we generalize the existing approach to an arbitrary N-dimensional k-state CA with either a deterministic or probabilistic update rule. Our proposed extension establishes a distinction between different kinds of defects that can propagate, as well as the direction in which they propagate. Furthermore, in order to arrive at a comprehensive insight into CA’s stability, we introduce additional concepts, such as the average Lyapunov exponent and the correlation coefficient of the difference pattern growth. We illustrate our approach for some interesting three-state and four-state rules, as well as a CA-based forest-fire model. In addition to making the existing methods generally applicable, our extension makes it possible to identify some behavioral features that allow us to distinguish a Class IV CA from a Class III CA (according to Wolfram’s classification), which has been proven to be difficult.
Effect of electromagnetic wave reflection from conducting surfaces on blob dynamics in the tokamak scrape-off layer
Authors: Stepanenko A. A.
Published: April 2023

Electromagnetic dynamics of blobs in hot scrape-off-layer plasmas of the tokamak are affected by excitation of the Alfvén waves and their subsequent propagation to the machine first wall along open magnetic field lines. In this study, the interaction of electromagnetic perturbations with the conducting tokamak wall and the resulting impact of these perturbations on the motion of filaments at the tokamak edge are analyzed. The model describing blob dynamics is presented. To describe the reflection of the Alfvén waves from the tokamak wall, the new form of sheath boundary conditions for the parallel current and electrostatic potential at the plasma–sheath interface is proposed. It is demonstrated that depending on the wall resistivity, the waves can be either absorbed or reflected by the wall, influencing the excitation of electromagnetic fluctuations inside the filament plasma. The theoretical conclusions of the study are supported with the BOUT++ numerical modeling of blob dynamics at the edge of the DIII-D and NSTX tokamaks. It is shown that taking the reflective boundary conditions into account leads to the excitation of the standing Alfvén waves in the filament, periodically canceling the electrostatic currents inside the blob.
Classical nucleation of vapor between hydrophobic plates
Authors: Tinti Antonio , Giacomello Alberto , Meloni Simone , Casciola Carlo Massimo
Published: April 2023

In this work, an extended classical nucleation theory (CNT), including line tension, is used to disentangle classical and non-classical effects in the nucleation of vapor from a liquid confined between two hydrophobic plates at a nanometer distance. The proposed approach allowed us to gauge, from the available simulation work, the importance of elusive nanoscale effects, such as line tension and non-classical modifications of the nucleation mechanism. Surprisingly, the purely macroscopic theory is found to be in quantitative accord with the microscopic data, even for plate distances as small as 2 nm, whereas in extreme confinement (<1.5 nm), the CNT approximations proved to be unsatisfactory. These results suggest how classical nucleation theory still offers a computationally inexpensive and predictive tool useful in all domains where nanoconfined evaporation occurs—including nanotechnology, surface science, and biology.
Tuning the conductance topology in solids
Authors: Lopez-Richard Victor , Wengenroth Silva Rafael Schio , Lipan Ovidiu , Hartmann Fabian
Published: April 2023

The inertia of trapping and detrapping of nonequilibrium charge carriers affects the electrochemical and transport properties of both bulk and nanoscopic structures in a very peculiar way. An emerging memory response with hysteresis in the current–voltage response and its eventual multiple crossing, produced by this universally available ingredient, are signatures of this process. Here, we deliver a microscopic and analytical solution for these behaviors, understood as the modulation of the topology of the current–voltage loops. Memory emergence thus becomes a characterization tool for intrinsic features that affect the electronic transport of solids such as the nature and number of trapping sites, intrinsic symmetry constraints, and natural relaxation time scales. This method is also able to reduce the seeming complexity of frequency-dependent electrochemical impedance and cyclic voltammetry observable for a variety of systems to a combination of simple microscopic ingredients.
A rabbit shaped bidirectional linear ultrasonic motor driven by single-phase signal
Authors: Zhang Bing , Li Chaodong
Published: April 2023

A rabbit shaped block, single-phase, linear, ultrasonic motor is proposed. The motor is 17.7 × 9.1 × 6 mm3 in size, and the overall mass is 2.3 g. The motor is designed by referring to the rabbit running mode and the principle of a Langevin vibrator concentrator. It can realize bidirectional driving without changing the constraint position. First, the basic structure of the motor is introduced, and the working principle of the motor is discussed. Then, the motion trajectory and driving force of the motor driving foot are theoretically deduced and simulated, and the simulation results are verified by the modal impedance characteristic test. Finally, the mechanical characteristics of the motor prototype are tested. The results show that under the excitation voltage of 5 N preload and 200 Vpp, the motor is driven to the right in B1 mode, the no-load speed is 42.3 mm/s, the maximum driving force is 0.28 N, and the stall torque is 0.27 Nm. Correspondingly, the motor is driven in reverse in B2 mode, the no-load speed is 118 mm/s, the maximum driving force is 1.48 N, and the stall torque is 1.41 Nm.
Dusty plasmas above the sunlit surface of Mercury
Authors: Popel S. I. , Golub' A. P. , Zelenyi L. M.
Published: April 2023

Above the sunlit surface of Mercury, the properties and formation of dusty plasmas are investigated. It is demonstrated that the dusty plasmas are formed for subsolar angles exceeding approximately 76° due to photoelectric and electrostatic processes. As a result, the dusty plasmas are present in the polar regions of Mercury, characterized by latitudes of about 70° and above. The formation of dusty plasmas is also possible for lower latitudes, but only where the surface profile allows it. Plasmas above the sunlit surface of Mercury consist, in particular, of photoelectrons, electrons, and ions of the solar wind, and also charged dust particles. The distribution functions of photoelectrons near the surface of Mercury, as well as the altitude dependences of the number densities of dust particles, their charges and sizes, as well as electric fields, are obtained. The calculations are carried out which correspond to the position of Mercury at aphelion and perihelion of its orbit for the situations of dusty plasma location in the vicinity of magnetic poles of Mercury and in other regions. It is shown that there are qualitative differences between the dusty plasma systems of Mercury and the Moon related to the fact that Mercury has a magnetosphere and Mercury's orbit is one of the most eccentric of all planetary orbits in the Solar System. The effects of magnetic fields can slightly influence the dust particle transport and, correspondingly, the expansion of the region of the existence of dusty plasmas above the surface of Mercury due to the effect of dust particle transport is not so significant as at the Moon. Furthermore, due to the presence of Mercury's magnetosphere, the solar wind is important for the formation of dusty plasmas at Mercury only in the vicinity of the regions of the magnetic poles. In other regions of Mercury, in contrast to the situation at the Moon, the solar wind does not influence significantly the dusty plasma properties. The dusty plasma parameters are different in the cases of aphelion and perihelion of the orbit of Mercury.
Structure formation of rod-like fillers in a contraction flow
Authors: Gruhn Thomas , Ortiz Monsalve Camilo , Salehi Sahar
Published: April 2023

Rod-like fillers in a flow field of a viscous fluid may form complex structures after passing a sudden contraction. The rods start with a dilute distribution with random positions and orientations. Behind the contraction, a large amount of rods tumble in a spatially correlated way, such that orientations perpendicular to the flow field occur at regular distances along the channel. The correlated tumbling results from an interplay of several effects, the tumbling inferred by the space dependent shear flow, the accumulation of rods at a certain distance from the wall, and the rod alignment at the contraction. The system is studied numerically for rod-like fillers in a shear-thinning viscous fluid.
Dynamical commensuration effect in a two-dimensional Yukawa solid modulated by periodic substrates
Authors: Zhu Wenqi , Reichhardt C. , Reichhardt C. J. O. , Feng Yan
Published: April 2023

Transverse depinning dynamics of a periodic-square-substrate modulated two-dimensional dusty plasma solid driven by a constant force in the longitudinal direction are investigated using Langevin dynamical simulations. When the commensuration ratio (the number ratio of particles to substrate potential wells) is increased, there is a nonmonotonic variation of the critical transverse depinning force, and the local maxima and minima of the critical transverse depinning force precisely correspond to the dynamical commensurate and incommensurate conditions, respectively. The dynamical commensuration effect is also clearly visible in the stable one-dimensional channel particle trajectories and the highly ordered structure, while both the particle trajectories and the structure are more disordered under the incommensurate conditions. The nonmonotonic variation of the critical transverse depinning force is attributed to the stability of the lattice structure at specific commensuration ratios.
An exact solution for directional cell movement over Jeffrey slime layer with surface roughness effects
Authors: Asghar Zeeshan , Elmoasry Ahmed , Shatanawi Wasfi , Gondal Muhammad Asif
Published: April 2023

The role of marine microbes in the aquatic ecosystem is dynamic. The current work explores the fluid mechanics of gliding organisms near a porous boundary. Surface roughness effects are utilized on the lower substrate. The ooze layer between the two-dimensional sheet (micro-swimmers) and the rough substrate is considered a non-Newtonian Jeffrey fluid. The laminar flow of incompressible slime is generated by organism movement. Darcy's law is applied to capture the porous effects. This law is compatible with our study since the laminar flow of slime is driven via bacterial movement. The lubrication assumption is utilized on Navier–Stokes equations. The closed-form solution of a reduced differential equation is calculated. The unknowns present in the boundary conditions are refined by the root-finding algorithm. Finally, the organism speed, flow rate, energy losses, and streamlines are visually represented. These obtained results are elaborated, and key points are mentioned at the end.
Detecting ultrafast turbulent oscillations in near-nozzle discharged liquid jet using x-ray phase-contrast imaging with MHz frequency
Authors: Atac Omer Faruk
Published: April 2023

Characteristics of a discharged liquid jet in near-nozzle are determined by the in-flow turbulences generated by the evolution of inflow vortices and cavitation. High-fidelity simulations have indicated that such physical processes can generate ultrafast turbulent fluctuations (in the range of MHz) originating from the nature of turbulence by the interaction between the large and small-scale turbulence in the flow. Detecting ultrafast turbulent oscillations while resolving small-scale turbulences in the optically dense near-nozzle liquid jet has not been observed through experimental methods so far. In this study, therefore, ultrafast x-ray phase-contrast imaging, which can provide a clear image in the near-field using a high-energy x-ray source, was applied to observe the fluctuation of flow velocity in the near-field to obtain the ultrafast turbulent oscillations at the discharged jet. To capture the ultrafast variance of flow velocity originating from the nature of turbulence, the high imaging frequency was applied up to 1.2 MHz. With the implemented methodology, turbulence intensity distributions of discharged liquid jets were measured for various injection pressures and nozzle geometries. Such turbulence intensity results were also correlated with the initial dispersion angle of the spray. In addition, the turbulence length scales, which can be detected through the current methodology, were estimated and discussed considering standard-length scales. The results showed that the current experimental method introduced in this study can provide important insights into the turbulence characteristics of spray by resolving Taylor scale turbulences and can provide valuable validation data and boundary conditions for reliable spray simulations.
Transferability of vibrational spectroscopic map from TIP4P to TIP4P-like water models
Authors: Takayama Tetsuyuki , Otosu Takuhiro , Yamaguchi Shoichi
Published: April 2023

We computed the IR, Raman, and sum frequency generation spectra of water in the OH-stretch region by employing the quantum/classical mixed approach that consists of a vibrational spectroscopic map and molecular dynamics (MD) simulation. We carried out the MD simulation with the TIP4P, TIP4P/2005, and TIP4P/Ice models and applied the map designed for TIP4P by Skinner et al. to each MD trajectory. Although the map is not tuned for TIP4P-like models, TIP4P/2005 and TIP4P/Ice provide the best reproduction of the experimental vibrational spectra of liquid water and crystalline ice, respectively. This result demonstrates the transferability of the map from TIP4P to TIP4P/2005 and TIP4P/Ice, meaning that one can choose an appropriate TIP4P-like model to calculate the vibrational spectra of an aqueous system without rebuilding the map.
Development of an energy spread analyzer for secondary ion mass spectrometry ion source
Authors: Zhou Y. , Zhai Y. J. , Jin Q. Y. , Liu Y. G. , Li L. B. , Zhang P. , Zhang S. , Zhao H. W. , Sun L. T.
Published: April 2023

The energy spread (ΔE) of an ion source is an important parameter in the production of a finely focused primary ion beam applied in secondary ion mass spectrometry (SIMS). A variable-focusing retarding field energy analyzer (RFEA) has been developed and tested with an Ar+ beam and an oxygen ion beam extracted from a 2.45 GHz microwave ion source, which is developed as a candidate ion source for SIMS applications. The simulation results show that the relative resolution ΔE/E of the designed RFEA reaches 7 × 10−5. The experimental results indicate that a focusing electrode can improve the ΔE measurement results, which is consistent with the simulation results. The ion energy distributions of the Ar+ beam and oxygen ion beam are of Gaussian distribution with the value of ΔE of 3.3 and 2.9 eV, respectively. These results indicate that the designed RFEA is reliable for measuring the ion beam energy spread. The developed RFEA is also used to study the plasma behavior in different settings, which reveals that plasma stability is critical to making a low energy spread ion beam. This paper will present the simulation, design, and test of the variable-focusing RFEA. Preliminary ion beam quality studies with this instrument will also be discussed.
Preface to Special Topic: Plasma Physics from the Magnetospheric Multiscale Mission
Authors: Stawarz Julia E. , Genestreti Kevin J.
Published: April 2023

NASA's Magnetospheric Multiscale (MMS) mission is a four-spacecraft formation of Earth orbiting satellites that have been providing unparalleled measurements of the local kinetic-scale plasma dynamics in near-Earth space for the past 8 years. The spacecraft carry a full complement of space plasma instrumentation capable of measuring the 3D electromagnetic fields and particle distribution functions at cadences up to 100 times faster than previous missions and with interspacecraft separations as small as ∼ 5 km, approaching the characteristic electron scales in many of the plasmas that MMS samples. In this Special Topic, we bring together 26 papers covering a broad range of topics—from magnetic reconnection, shocks, and turbulence to some of the basic nuances of collisionless dynamics—highlighting the many ways in which MMS is helping us to better understand both the dynamics of Earth's magnetosphere and the fundamental physics of plasmas.
Surface patches induce nonspecific binding and phase separation of antibodies
Authors: Ausserwöger Hannes , Krainer Georg , Welsh Timothy J. , Thorsteinson Nels , de Csilléry Ella , Sneideris Tomas , Schneider Matthias M. , Egebjerg Thomas , Invernizzi Gaetano , Herling Therese W. , Lorenzen Nikolai , Knowles Tuomas P. J.
Published: April 2023

Nonspecific interactions are a key challenge in the successful development of therapeutic antibodies. The tendency for nonspecific binding of antibodies is often difficult to reduce by rational design, and instead, it is necessary to rely on comprehensive screening campaigns. To address this issue, we performed a systematic analysis of the impact of surface patch properties on antibody nonspecificity using a designer antibody library as a model system and single-stranded DNA as a nonspecificity ligand. Using an in-solution microfluidic approach, we find that the antibodies tested bind to single-stranded DNA with affinities as high as
K
D
= 1 µM. We show that DNA binding is driven primarily by a hydrophobic patch in the complementarity-determining regions. By quantifying the surface patches across the library, the nonspecific binding affinity is shown to correlate with a trade-off between the hydrophobic and total charged patch areas. Moreover, we show that a change in formulation conditions at low ionic strengths leads to DNA-induced antibody phase separation as a manifestation of nonspecific binding at low micromolar antibody concentrations. We highlight that phase separation is driven by a cooperative electrostatic network assembly mechanism of antibodies with DNA, which correlates with a balance between positive and negative charged patches. Importantly, our study demonstrates that both nonspecific binding and phase separation are controlled by the size of the surface patches. Taken together, these findings highlight the importance of surface patches and their role in conferring antibody nonspecificity and its macroscopic manifestation in phase separation.
Structural basis of calmodulin modulation of the rod cyclic nucleotide-gated channel
Authors: Barret Diane C. A. , Schuster Dina , Rodrigues Matthew J. , Leitner Alexander , Picotti Paola , Schertler Gebhard F. X. , Kaupp U. Benjamin , Korkhov Volodymyr M. , Marino Jacopo
Published: April 2023

Calmodulin (CaM) regulates many ion channels to control calcium entry into cells, and mutations that alter this interaction are linked to fatal diseases. The structural basis of CaM regulation remains largely unexplored. In retinal photoreceptors, CaM binds to the CNGB subunit of cyclic nucleotide-gated (CNG) channels and, thereby, adjusts the channel’s Cyclic guanosine monophosphate (cGMP) sensitivity in response to changes in ambient light conditions. Here, we provide the structural characterization for CaM regulation of a CNG channel by using a combination of single-particle cryo-electron microscopy and structural proteomics. CaM connects the CNGA and CNGB subunits, resulting in structural changes both in the cytosolic and transmembrane regions of the channel. Cross-linking and limited proteolysis-coupled mass spectrometry mapped the conformational changes induced by CaM in vitro and in the native membrane. We propose that CaM is a constitutive subunit of the rod channel to ensure high sensitivity in dim light. Our mass spectrometry-based approach is generally relevant for studying the effect of CaM on ion channels in tissues of medical interest, where only minute quantities are available.
Giant Tunneling Magnetoresistance in Spin-Filter Magnetic Tunnel Junctions Based on van der Waals A-Type Antiferromagnet CrSBr
Authors: Lan Guibin , Xu Hongjun , Zhang Yu , Cheng Chen , He Bin , Li Jiahui , He Congli , Wan Caihua , Feng Jiafeng , Wei Hongxiang , Zhang Jia , Han Xiufeng , Yu Guoqiang
Published: April 2023

Two-dimensional van der Waals magnetic materials have demonstrated great potential for new-generation high-performance and versatile spintronic devices. Among them, magnetic tunnel junctions (MTJs) based on A-type antiferromagnets, such as CrI3, possess record-high tunneling magnetoresistance (TMR) because of the spin filter effect of each insulating unit ferromagnetic layer. However, the relatively low working temperature and the instability of the chromium halides hinder applications of this system. Using a different technical scheme, we fabricated the MTJs based on an air-stable A-type antiferromagnet, CrSBr, and observed a giant TMR of up to 47000% at 5 K. Meanwhile, because of a relatively high Néel temperature of CrSBr, a sizable TMR of about 50% was observed at 130 K, which makes a big step towards spintronic devices at room temperature. Our results reveal the potential of realizing magnetic information storage in CrSBr-based spin-filter MTJs.
Nonadiabatic tunneling ionization of atoms in few-cycle elliptically polarized laser pulses
Authors: Liu Yupeng , Xie Wenhai , Li Min , Cao Chuanpeng , Zhou Yueming , Lu Peixiang
Published: April 2023

We theoretically investigate nonadiabatic effects in tunneling ionization of a hydrogen atom induced by a few-cycle elliptically polarized laser pulse. We find a deflection angle between the maximum of the photoelectron momentum distribution and the direction of the negative vector potential corresponding to the electric-field peak. This deflection angle mainly originates from the fact that the instant of the maximal ionization rate does not exactly correspond to the instant of the electric-field peak in the few-cycle elliptically polarized laser pulse, revealing an ionization time shift between those two instants. The ionization time shift is a result of the nonadiabatic effect induced by the envelope of the few-cycle elliptically polarized laser pulse, which disappears in a long-pulsed laser. Our study is useful for understanding attoclock experiments using few-cycle elliptically polarized laser pulses.
Experimental comparison of relative stopping power evaluation between proton CT and x-ray CT for pre-clinical proton irradiation studies of small animals
Authors: Terakawa Atsuki , Hosokawa Hibiki , Nogami Mitsuhiro , Hitomi Keitaro , Ishii Keizo
Published: April 2023

Objective. Proton therapy experiments in small animals are useful not only for pre-clinical and translational studies, but also for the development of advanced technologies for high-precision proton therapy. While treatment planning for proton therapy is currently based on the stopping power of protons relative to water (i.e. the relative stopping power (RSP)), estimated by converting the CT number into RSP (Hounsfield unit (HU)-RSP conversion) in reconstructed x-ray computed tomography (XCT) images, the HU-RSP conversion causes uncertainties in RSP, which affect the accuracy of dose simulation in patients. Proton computed tomography (pCT) has attracted a great deal of attention due to its potential to reduce RSP uncertainties in clinical treatment planning. However, as the proton energies for irradiating small animals are much lower than those used clinically, the energy dependence of RSP may negatively affect pCT-based RSP evaluation. Here, we explored whether the low-energy pCT approach provided more accurate RSPs when planning proton therapy treatment for small animals. Approach. We evaluated the RSPs of 10 water- and tissue-equivalent materials with known constituent elements based on pCT measurements conducted at 73.6 MeV, then compared them with XCT-based and calculated RSPs to investigate energy dependence and achieve more accurate RSPs for treatment planning in small animals. Main results. Despite the low proton energy, the pCT approach for RSP evaluation yields a smaller root mean square deviation (1.9%) of RSP from the theoretical prediction, compared to conventional HU-RSP conversion with XCT (6.1%). Significance. Low-energy pCT is expected to improve the accuracy of proton therapy treatment planning in pre-clinical studies of small animals if the RSP variation that can be attributed to energy dependence is identical to the variation in the clinical proton energy region.
A novel inchworm piezoelectric actuator using two-stage amplification mechanism with high speed: design, modeling, and experimental evaluation
Authors: Yu Simiao , Liang JiaYu , Yang Fan , Wang Haitao , Liu Xianglong , Xu Chao , Wang Zhen , Xu Dongmei
Published: April 2023

The inchworm piezoelectric actuator has a wide application prospect in the field of precision instruments. However, in view of the complex structure of the existing inchworm piezoelectric actuator and the far distance between the driving feet of the actuator, it is difficult to realize alternate driving and the high output speed of the driving feet, etc. In this paper, an inchworm piezoelectric linear actuator based on two-stage amplification mechanism is designed, which amplifies the output displacement of the driving feet by two-stage amplification mechanism, and improves the driving efficiency of the actuator stator by the way of alternating driving. We present an inchworm piezoelectric actuator with three piezoelectric stacks and a two-stage amplification mechanism, which is simple in structure design, compact in actuator structure and easy to realize alternate driving. The kinematics and dynamics models of the inchworm piezoelectric actuator are established by analyzing the flexible hinge and its structure with the pseudo-rigid body method. The length of the lever structure and the angle of the triangular structure of the piezoelectric actuator are solved by kinematics, and the natural frequency of the whole structure is calculated by dynamics. Through finite element analysis, the simulation magnification ratio of the piezoelectric actuator is obtained, so as to evaluate and verify the theoretical calculation and further optimize the structure. The experimental results show that the inchworm piezoelectric linear actuator using two-stage amplification mechanism has a high driving speed of 5.53 mm s−1 under voltage of 135 V and frequency of 70 Hz.