bluuebunny/crossref_metadata_2025 huggingface dataset:
Quasiuniversal scaling in mouse-brain neuronal activity stems from edge-of-instability critical dynamics
Authors: Morales Guillermo B. , di Santo Serena , Muñoz Miguel A.
Published: February 2023

The brain is in a state of perpetual reverberant neural activity, even in the absence of specific tasks or stimuli. Shedding light on the origin and functional significance of such a dynamical state is essential to understanding how the brain transmits, processes, and stores information. An inspiring, albeit controversial, conjecture proposes that some statistical characteristics of empirically observed neuronal activity can be understood by assuming that brain networks operate in a dynamical regime with features, including the emergence of scale invariance, resembling those seen typically near phase transitions. Here, we present a data-driven analysis based on simultaneous high-throughput recordings of the activity of thousands of individual neurons in various regions of the mouse brain. To analyze these data, we construct a unified theoretical framework that synergistically combines a phenomenological renormalization group approach and techniques that infer the general dynamical state of a neural population, while designing complementary tools. This strategy allows us to uncover strong signatures of scale invariance that are “quasiuniversal” across brain regions and experiments, revealing that all the analyzed areas operate, to a greater or lesser extent, near the edge of instability.
Dynamical formation of two-fold fragmented many-body state induced by an impurity in a double-well
Authors: Chen Jie , Mistakidis Simeon I , Schmelcher Peter
Published: February 2023

We unravel the correlated quantum quench dynamics of a single impurity immersed in a bosonic environment confined in an one-dimensional double-well potential. A particular emphasis is placed on the structure of the time-evolved many-body (MB) wave function by relying on a Schmidt decomposition whose coefficients directly quantify the number of configurations that are macroscopically populated. For a non-interacting bosonic bath and weak postquench impurity-bath interactions, we observe the dynamical formation of a two-fold fragmented MB state which is related to intra-band excitation processes of the impurity and manifests as a two-body phase separation (clustering) between the two species for repulsive (attractive) interactions. Increasing the postquench impurity-bath coupling strength leads to the destruction of the two-fold fragmentation since the impurity undergoes additional inter-band excitation dynamics. By contrast, a weakly interacting bath suppresses excitations of the bath particles and consequently the system attains a weakly fragmented MB state. Our results explicate the interplay of intra- and inter-band impurity excitations for the dynamical generation of fragmented MB states in multi-well traps and for designing specific entangled impurity states.
Physics informed neural networks for electric field distribution characteristics analysis
Authors: Zeng Xin , Zhang Shuai , Ren Chenhua , Shao Tao
Published: February 2023

Electric field calculations based on the Poisson equation have been widely used in high voltage and plasma technology. However, in practical applications, the electric field distribution in space is relatively complex, and the simulation technology based on the traditional method is often a simplification of reality, which leads to a large error between the simulation and the actual measured value. In the actual application process, due to the limitation of measurement methods, it is necessary to infer the electric field data at other locations in space according to the measurement results. Physics informed neural networks (PINNs) are introduced into the electric field calculation. PINNs are considered partial differential equation solvers based on deep neural networks. In this paper, 2D and 3D electric field distributions are discussed and compared with the finite element method. A method of dividing the dielectric distribution based on the sigmoid function is proposed, which can be effectively used to construct the spatial electric field model of the homogeneous dielectric. The combination of the data and physical model based on PINNs establishes a method to solve the inverse problem of the relative permittivity in the electric field. The results show that PINNs can calculate the distribution of the electric field according to the physical equations and different types of constraints and parameters.
Redox phase transformations in magnetite nanoparticles: impact on their composition, structure and biomedical applications
Authors: Lavorato Gabriel C , de Almeida Adriele A , Vericat Carolina , Fonticelli Mariano H
Published: February 2023

Magnetite nanoparticles (NPs) are one of the most investigated nanomaterials so far and modern synthesis methods currently provide an exceptional control of their size, shape, crystallinity and surface functionalization. These advances have enabled their use in different fields ranging from environmental applications to biomedicine. However, several studies have shown that the precise composition and crystal structure of magnetite NPs depend on their redox phase transformations, which have a profound impact on their physicochemical properties and, ultimately, on their technological applications. Although the physical mechanisms behind such chemical transformations in bulk materials have been known for a long time, experiments on NPs with large surface-to-volume ratios have revealed intriguing results. This article is focused on reviewing the current status of the field. Following an introduction on the fundamental properties of magnetite and other related iron oxides (including maghemite and wüstite), some basic concepts on the chemical routes to prepare iron oxide nanomaterials are presented. The key experimental techniques available to study phase transformations in iron oxides, their advantages and drawbacks to the study of nanomaterials are then discussed. The major section of this work is devoted to the topotactic oxidation of magnetite NPs and, in this regard, the cation diffusion model that accounts for the experimental results on the kinetics of the process is critically examined. Since many synthesis routes rely on the formation of monodisperse magnetite NPs via oxidation of wüstite counterparts, the modulation of their physical properties by crystal defects arising from the oxidation process is also described. Finally, the importance of a precise control of the composition and structure of magnetite-based NPs is discussed and its role in their biomedical applications is highlighted.
Effects of stochastic forces on the nonlinear behaviour of a silicon nitride membrane nanoelectromechanical resonator
Authors: Venkatachalam Srisaran , Zhou Xin
Published: February 2023

In this work, we present the effects of stochastic force generated by white noise on the nonlinear dynamics of a circular silicon nitride membrane. By tuning the membrane to the Duffing nonlinear region, detected signals switching between low- and high-amplitudes have been observed. They are generated by noise-assisted random jumps between bistable states at room temperature and exhibit high sensitivity to the driving frequency. Through artificially heating different mechanical vibration modes by external input of white noise, the switching rate exhibits exponential dependence on the effective temperature and follows with Kramer‘s law. Furthermore, both the measured switching rate and activation energy exhibit sensitivity to the width of the hysteresis window in nonlinear response and the driving force, which is in qualitative agreement with the theoretical descriptions. Besides, white noise-induced hysteresis window squeezing and bifurcation point shifting have also been observed, which are attributed to the stochastic force modulation of the spring constant of the membrane. These studies are carried out in an all-electric operating scheme at room temperature, paving the way for the exploration of probability distribution-based functional elements that can be massively integrated on-chip.
Temperature-dependent photoluminescence properties of single defects in AlGaN micropillars
Authors: Xue Yingxian , Chen Feiliang , Li Qian , Ju Zhiping , Cao Yujing , Zhang Shiyu , Yuan Xinrui , Wu Botao , Wu E
Published: February 2023

Single-photon emitters (SPEs) are attractive as integrated platforms for quantum applications in technologically mature wide-bandgap semiconductors since their stable operation at room temperature or even at high temperatures. In this study, we systematically studied the temperature dependence of the SPE in AlGaN micropillar by experiment. The photoluminescence (PL) spectrum, PL intensity, radiative lifetime and second-order autocorrelation function measurements are investigated over the temperature range from 303 to 373 K. The point defects of AlGaN show strong zero phonon line in the wavelength range of 800–900 nm and highly antibunched photon emission even up to 373 K. Our study reveals a possible mechanism for linewidth broadening in AlGaN SPE at high temperatures. This indicates a possible key for on-chip integration applications based on this material operating at high temperatures.
Built-in wavelet-induced smoothness to reduce plan complexity in intensity modulated radiation therapy (IMRT)
Authors: Tefagh Mojtaba , Zarepisheh Masoud
Published: February 2023

Objective. Reducing plan complexity in intensity modulated radiation therapy (IMRT) to ensure dosimetric accuracy and delivery efficiency of the radiation treatment plans. We propose a novel approach by representing the beamlet intensities using an incomplete wavelet basis that explicitly excludes fluctuating intensity maps from the decision space (explicit hard constraint). This technique provides a built-in wavelet-induced smoothness that improves both dosimetric plan quality and delivery efficiency. Approach. The beamlet intensity maps need to be especially smooth in the leaf travel direction (referred to as the X-direction). We treat the intensity map of each beam as a 2D image and represent it using the wavelets corresponding to low-frequency changes in the X-direction (i.e. approximation and horizontal). The absence of wavelets corresponding to high-frequency changes (i.e. vertical and diagonal) induces built-in smoothness. We still utilize a regularization term in the objective function to promote smoothness in the Y-direction (perpendicular to the X-direction) and further possible smoothness in the X-direction. This technique has been tested on three patient cases of different disease sites (paraspinal, lung, prostate) and all final evaluations and comparisons have been performed on an FDA-approved commercial treatment planning system (Varian EclipseTM). Main results. Wavelet-induced smoothness reduced monitor units by about 10%, 45%, and 14% for paraspinal, lung, and prostate cases, respectively. It also improved organ at risk sparing, especially on the complex paraspinal case where it resulted in about 7%, 13%, and 14% less mean dose to esophagus, lung, and cord, respectively. Moreover, built-in wavelet-induced smoothness desensitizes the results to changing the weight associated to the regularization term, and thereby mitigates the weight fine-tuning difficulty. Significance. Fluence smoothness is often achieved by smoothing the beamlet intensity maps using a proper regularization term in the objective function aiming at disincentivizing fluctuation in the beamlet intensities (implicit soft constraint). This work reports a novel application of wavelets in imposing an explicit smoothness hard constraint in the search space using an incomplete wavelet basis. This idea has been successfully applied to exclude complex and clinically irrelevant radiation plans from the search space. The code and pertained models along with a sample dataset are released on our LowDimRT GitHub (https://github.com/PortPy-Project/LowDimRT).
Multifunctional soft stretchable strain sensor for complementary optical and electrical sensing of fatigue cracks
Authors: Liu Han , Kollosche Matthias , Laflamme Simon , Clarke David R
Published: February 2023

Fatigue-induced cracking in steel components and other brittle materials of civil structures is one of the primary mechanisms of degrading structural integrity and can lead to sudden failures. However, these cracks are often difficult to detect during visual inspections, and off-the-shelf sensing technologies can generally only be used to monitor already identified cracks because of their spatial localization. A solution is to leverage advances in large area electronics to cover large surfaces with skin-type sensors. Here, the authors propose an elastic and stretchable multifunctional skin sensor that combines optical and capacitive sensing properties. The multifunctional sensor consists of a soft stretchable structural color film sandwiched between transparent carbon nanotube electrodes to form a parallel plate capacitor. The resulting device exhibits a reversible and repeatable structural color change from light blue to deep blue with an angle-independent property, as well as a measurable change in capacitance, under external mechanical strain. The optical function is passive and engineered to visually assist in localizing fatigue cracks, and the electrical function is added to send timely warnings to infrastructure operators. The performance of the device is characterized in a free-standing configuration and further extended to a fatigue crack monitoring application. A correlation coefficient-based image processing method is developed to quantify the strain measured by the optical color response. Results show that the sensor performs well in detecting and quantifying fatigue cracks using both the color and capacitive signals. In particular, the color signal can be measured with inexpensive cameras, and the electrical signal yields good linearity, resolution, and accuracy. Tests conducted on two steel specimens demonstrate a minimum detectable crack length of 0.84 mm.
Polarization and phase control of electron injection and acceleration in the plasma by a self-steepening laser pulse
Authors: Kim Jihoon , Wang Tianhong , Khudik Vladimir , Shvets Gennady
Published: February 2023

We describe an interplay between two injection mechanism of background electrons into an evolving plasma bubble behind an intense laser pulse: one due to the overall bubble expansion, and another due to its periodic undulation. The two mechanisms occur simultaneously when an intense laser pulse propagating inside a plasma forms a shock-like steepened front. Periodic undulations of the plasma bubble along the laser propagation path can either inhibit or conspire with electron injection due to bubble expansion. We show that carrier-envelope-phase (CEP) controlled plasma bubble undulation induced by the self-steepening laser pulse produces a unique electron injector—expanding phase-controlled undulating bubble (EPUB). The longitudinal structure of the electron bunch injected by the EPUB can be controlled by laser polarization and power, resulting in high-charge (multiple nano-Coulombs) high-current (tens of kilo-amperes) electron beams with ultra-short (femtosecond-scale) temporal structure. Generation of high-energy betatron radiation with polarization- and CEP-controlled energy spectrum and angular distribution is analyzed as a promising application of EPUB-produced beams.
Visualization of fast ion phase-space flow in plasmas well-below, near and well-above Alfvén eigenmode stability threshold in tokamak
Authors: Du X.D. , Heidbrink W.W. , Van Zeeland M.A. , Gonzalez-Martin J. , Austin M.E. , Yan Z. , McKee G.R.
Published: February 2023

Transport of fast ions along certain local phase space paths, referred to as fast ion phase-space flow, has been systematically measured by an imaging neutral particle analyzer (INPA) in three plasma regimes, which are well-below, near, and well-above the Alfvén eigenmode stability threshold (Du et al 2021 Phys. Rev. Lett.
127 235002). (1) In plasmas well-below the Alfvén eignenmodes (AE) stability threshold, fast ions are well-confined on passing particle orbits without noticeable transport over the phase space. The observed INPA images agree well with the synthetic INPA images, using the fast ion distribution predicted by neoclassical theory. (2) In plasmas near the AE stability threshold, INPA images in the presence of AE activity moderately deviate from those without AE activity. The image difference can be well interpreted by AE-driven, phase-space fast ion flow. Paths of this flow over the velocity space (or streamlines) are reconstructed by the intersection lines of curved Eʹ and µ surfaces, referred to as Eʹ and µ line (where

E

′

≡
E
−
(
ω

/

n
)

P

ζ

; E, P

ζ
and µ are the energy, canonical toroidal momentum and magnetic moment of ions; ω and n are the angular frequency and toroidal mode number of AEs, respectively). Resonant fast ions move radially inward by gaining energy and move radially outward by losing energy and the trajectory well aligns with the Eʹ and µ lines that pass through the mode resonances near the injection energy of neutral beams. (3) In plasmas well-above the AE stability threshold, fast ion phase-space dynamics shows additional features. Fast ions are transported out of the birth positions so promptly along the streamlines that the slowing-down process from the injection energy is not observable, exhibiting strong critical gradient behavior at local phase space. As a result, the increase of electron temperature is very small, in spite of an increase of beam power by

∼

45
%

. It should be emphasized that the directions of phase-space transport, induced by AEs with different frequencies, structures and mode numbers, do not largely differ.
Argon–seeded detachment during ELM control by RMPs in KSTAR
Authors: Shin H. , Hwang J. , Han Y. , Shin G. , Lee H. , Chai K.-B. , Choe Wonho
Published: February 2023

In this study, we demonstrate argon-seeded discharges that exhibited a detached divertor during the full suppression and mitigation of edge-localized modes (ELMs) by an International Thermonuclear Experimental Reactor-like, three-row resonant magnetic perturbation (RMP) configuration in KSTAR. During the ELM suppression phase, the peak heat flux on the divertor target was successfully reduced from 1.6 MW m−2–0.5 MW m−2 via argon seeding. Further, the ion saturation current densities corresponding to the particle fluxes on both targets were reduced by more than 50%. During the RMP grassy-ELM regime, a further reduction to 0.1 MW m−2 in the divertor heat load was successfully achieved. A highly localized radiation zone near the X-point was also observed during divertor detachment. The calculated degree of detachment based on the two-point model increased to levels of approximately 3 and 2.3 for the outer target and inner target cases, respectively. These results provide valuable information regarding the effect of mid-Z impurities on RMP-detachment-compatible discharges.
Theoretical evaluation of the tritium extraction from liquid metal flows through a free surface and through a permeable membrane
Authors: Urgorri F.R. , Garcinuño B. , Moreno C. , Rapisarda D.
Published: February 2023

Effective tritium extraction from PbLi flows is a requirement for the functioning of any PbLi based breeding blanket concept. For a continuous plant operation, the removal of the tritium dissolved in the PbLi has to be performed in line and sufficiently fast. Otherwise, tritium inventories in the liquid metal, start-up inventories and buffer inventories would be excessive from the safety point of view. Moreover, a slow response of the tritium extraction systems could also compromise the tritium self-sufficiency of the plant. A promising solution to this problem is to use highly permeable membranes in contact with the PbLi flow to promote the extraction via permeation. This technique is usually known as Permeation Against Vacuum (PAV). As an alternative, tritium could be extracted directly by permeation through a fluid free surface (FS) in contact with vacuum. In both configurations, the dynamics of tritium transport is ruled by a combination of convection, diffusion and surface recombination. In this paper, the tritium extraction processes in the FS and PAV configurations are studied in detail. For the first time, general analytical expressions for the extraction efficiency are derived for both techniques in a Cartesian geometry. These expressions are general in the sense that they do not impose any kind of assumption concerning the permeation regime of the membrane or the fluid boundary layer. The derived expressions have been used to analyze numerically the response of both configurations in a close loop system, such as the one of DEMO. The presented methodology allows comparing the FS and PAV configurations, assessing in which conditions one will be behave better than other.
Achievement of ion temperatures in excess of 100 million degrees Kelvin in the compact high-field spherical tokamak ST40
Authors: McNamara S.A.M. , Asunta O. , Bland J. , Buxton P.F. , Colgan C. , Dnestrovskii A. , Gemmell M. , Gryaznevich M. , Hoffman D. , Janky F. , Lister J.B. , Lowe H.F. , Mirfayzi R.S. , Naylor G. , Nemytov V. , Njau J. , Pyragius T. , Rengle A. , Romanelli M. , Romero C. , Sertoli M. , Shevchenko V. , Sinha J. , Sladkomedova A. , Sridhar S. , Takase Y. , Thomas P. , Varje J. , Vincent B. , Willett H.V. , Wood J. , Zakhar D. , Battaglia D.J. , Kaye S.M. , Delgado-Aparicio L.F. , Maingi R. , Mueller D. , Podesta M. , Delabie E. , Lomanowski B. , Marchuk O. ,   the ST40 Team
Published: February 2023

Ion temperatures of over 100 million degrees Kelvin (8.6 keV) have been produced in the ST40 compact high-field spherical tokamak (ST). Ion temperatures in excess of 5 keV have not previously been reached in any ST and have only been obtained in much larger devices with substantially more plasma heating power. The corresponding fusion triple product is calculated to be

n

i
0

T

i
0

τ
E

≈
6
±
2
×

10

18

m

−
3

keVs

. These results demonstrate for the first time that ion temperatures relevant for commercial magnetic confinement fusion can be obtained in a compact high-field ST and bode well for fusion power plants based on the high-field ST.
An Introduction to PT-Symmetric Quantum Mechanics-Time-Dependent Systems
Authors: Fring A
Published: February 2023

I will provide a pedagogical introduction to non-Hermitian quantum systems that are PT-symmetric, that is they are left invariant under a simultaneous parity transformation (P) and time-reversal (T). I will explain how generalised versions of this antilinear symmetry can be utilised to explain that these type of systems possess real eigenvalue spectra in parts of their parameter spaces and how to set up a consistent quantum mechanical framework for them that enables a unitary time-evolution. In the second part I will explain how to extend this framework to explicitly time-dependent Hamiltonian systems and report in particular on recent progress made in this context. I will explain how to construct the essential key quantity in this framework, the time-dependent Dyson map and metric and solutions to the time-dependent Schrödinger equation, in an algebraic fashion, using time-dependent Darboux transformations, utilising Lewis-Riesenfeld invariants, point transformations and some approximation methods. I comment on the ambiguities of this metric and demonstrate that this can even lead to infinite series of metric operators. I conclude with some applications to PT-symmetrically coupled oscillators, demonstrate the equivalence of the time-dependent double wells and unstable anharmonic oscillators and show how the unphysical PT-symmetrically broken regions in the parameter space for the time-independent theory becomes physical in the explicitly time-dependent systems. I discuss how this leads to a prolongation of the otherwise rapidly decaying von Neumann entropy. The so-called sudden death of the entropy is stopped at a finite value.1
Optomechanical Simulation of a Parametric Oscillator
Authors: Onah F E , Ventura-Velázquez C , Maldonado-Villamizar F H , Jaramillo-Ávila B R , Rodríguez-Lara B M
Published: February 2023

We study an optomechanical device supporting at least three optical modes in the infrared telecommunication band and three mechanical vibration modes. We model the coherent driving of each optical mode, independently of each other, to obtain an effective Hamiltonian showing the different types of parametric processes allowed in the device. We propose a bichromatic driving scheme, in the lossy optical cavity regime, under a mean field approximation, that provides the quantum simulation of a parametric oscillator with optical control of its parameters.
Parameter Estimation via Indefinite Causal Structures
Authors: Procopio L M
Published: February 2023

Quantum Fisher information is the principal tool used to give the ultimate precision bound on the estimation of parameters for quantum channels. In this work, we present analytical expressions for the quantum Fisher information with three noisy channels for the case where the channels are in superposition of causal orders. We found that the quantum Fisher information increases as the number of causal orders increases for certain combinations. We also show that certain combinations of causal orders attain higher precision on bounds than others for the same number of causal orders. Based on our results, we chose the best combinations of causal orders with three channels for probing schemes using indefinite causal structures.
Symmetry Analysis of the Square Well Potential
Authors: Suárez E , Santiago-Acosta R D , Lemus R
Published: February 2023

Symmetry considerations are taken into account when a particle in a square well potential is studied. This system may display natural degeneracy, accidental degeneracy or systematic accidental degeneracy depending on the depth of the potential. In order to obtain the solutions associated with an arbitrary potential an algebraic discrete variable representation approach based on Pöschl-Teller functions is proposed. It is proved that the geometrical group C
4v
is the symmetry group of the system for the case of a finite potential barrier. A similar analysis is carried out for the rectangular square well potential with commensurate sides. In both cases the symmetry projection is crucial to simplify the calculations.
Dynamics of the Quantum Rabi Model in the Adiabatic Regime
Authors: Castanos-Cervantes L O
Published: February 2023

The quantum Rabi model in the adiabatic and ultrastrong and deep strong coupling regimes is considered. Some of the differences with the Jaynes-Cummings model are illustrated by considering the evolution of states and the expected values and root-mean-square deviations of several physical quantities of the qubit-oscillator system.
Modified Poisson-Gauss Single-Function to Describe the GRIN of the Human Lens
Authors: Jaimes-Nájera A
Published: February 2023

The human lens plays a crucial role in the vision process, since it is responsible for the accommodation mechanism and for the reduction of optical aberrations. Its modeling is important for the comprehension of the relationship between its physiological and optical properties, and ultimately for ophthalmic purposes. In this work we propose a modified version of the Poisson-Gauss function to construct a lens model that permits the fine-tuning of optical properties of the corresponding schematic eye. Particularly, we analyze how the refractive power of a schematic eye varies as the modification of the Poisson-Gauss function is induced. This can be useful in the modeling of personalized eyes with ophthalmic relevance.
Temperature Dependence of Entanglement and Coherence in Fenna-Matthews-Olson Complex
Authors: González-Soria B , Delgado F
Published: February 2023

The high efficiency in excitation energy transfer observed in the Fenna-Matthews-Olson light-harvesting complex in green sulfur bacteria is due to its arrange of photo-pigments, called bacteriochlorophylls. They are central for the photosynthetic process of those bacteria being controversially associated to long-lived coherence. The study of this protein complex and its energy dynamics continues, trying to understand the environmental factors affecting it. This work explores the temperature effects in the behaviour of entanglement and coherence among bacteriochlorophyll excitation energy transfer within the Fenna-Matthews-Olson complex, considering the latest pigment-protein monomer arrangement of 8 bacteriochlorophylls. An analysis for the system evolution using the Hierarchical Equations of Motion method, a non-Markovian approach, is performed to get the global and semi-local entanglement, as well as the coherence in the system.
Quantum Authentication Using Double Teleportation
Authors: Cardoso-Isidoro C , Delgado F
Published: February 2023

A process involving quantum teleportation to teleport a state to two parties in superposition is presented. Then, the process is applied to cryptography. Concretely in this work, we present the process of cryptography authentication using an undefined qubit state and the double quantum teleportation presented previously. Since quantum cryptography protocols are susceptible of eavesdropping, then such a process is considered through an eavesdropper trying to steal the information to supplant the user of authentication in order to quantify certain limits of applicability.
Groundwater shapes North American river floods
Authors: Berghuijs Wouter R , Slater Louise J
Published: February 2023

The importance of soil moisture in triggering river floods is increasingly recognized. However, soil moisture represents only a fraction of the water stored in the unsaturated zone. In contrast, groundwater from the deeper, saturated zone, may contribute a significant proportion of river flow, but its effects on flooding are poorly understood. Here we analyze hydroclimatic records of thousands of North American watersheds spanning 1981–2018 to show that baseflow (i.e. groundwater-sustained river flows) affects the magnitude of annual flooding at time scales from days to decades. Annual floods almost always arise through the co-occurrence of high precipitation (rainfall + snowmelt) and baseflow. Flood magnitudes are often more strongly related to variations in antecedent baseflow than antecedent soil moisture and short-term (⩽3-day) extreme precipitation. In addition, multi-decadal trends in flood magnitude and decadal flood variations tend to better align with groundwater storage and baseflow trends than with changing precipitation extremes and soil moisture. This reveals the importance of groundwater in shaping North American river floods and often decouples the spatial patterns of flood trends from those of shifting precipitation extremes and soil moisture.
Viscous flow through macroscopic spherical cavities in an arbitrary configuration in a granular material
Authors: Sano Osamu
Published: February 2023

Viscous flow through macroscopic spherical cavities in a granular material is theoretically investigated. Number, size and configuration of the cavities are arbitrary, except that cavities are sufficiently distant to allow asymptotic analysis on their interaction, which is taken into account up to

O
(
a

/

l

)
3

, where a and l are the characteristic radius and inter-cavity distance, respectively. Dependence of the flow field, flux into respective cavities and stress field etc on the cavity size, separation distance and orientation are analyzed. As further examples, 1D-, 2D-, and 3D-array of equal size cavities are examined, by which onset of the collapse of cavity and development of the collapsed region are elucidated. The latter may predict landslides and other flow-induced catastrophic changes in the material with quasi-equilibrium solid structure, as well as microscale waterway formation in human tissue known as angiogenesis.
On interfacial stress transmission of carbon nanotubes/alumina composites
Authors: Yang Yang , Xin Zhou , Gao-Feng Wei
Published: February 2023

The interface of carbon nanotube (CNTs)/alumina ceramic composites has a very important effect on their mechanical properties. In this study, an appropriate theoretical cell model was established to study the interfacial stress transmission in CNT/alumina composites. The stress transfer equation is derived as follows: The tensile stress of the CNTs and interfacial shear stress were simulated under an axial tension load, and the relationship between the stress transmission and the effective length of the CNTs was analyzed. The theoretical results were compared with the finite element method (FEM) results, and the results were found to be in good agreement. This study can provide a theoretical basis for adjusting the appropriate length of CNTs and interfacial interactions under different tension loads.
Citric acid concentration tune of structural and magnetic properties in hematite (α−Fe2O3) nanoparticles synthesized by sol−gel method
Authors: Utari  , Maulidina Hikmah , Arilasita Retna , Widiyandari Hendri , Suharno  , Purnama Budi
Published: February 2023

This study synthesized hematite nanoparticles using the sol-gel method. The physical properties are modified by the citric acid concentration used as fuel. The resulting sample’s rhombohedral (hexagonal) structure and space group R3c were revealed by the XRD data. The Scherer formula revealed that the crystallite size at the most substantial peak was 32.14 nm, 24.58 nm, and 23.21 nm with an increase in the citric acid concentration of 0.3 M, 0.4 M, and 0.5 M, respectively. The FTIR spectrum’s absorption band reveals the properties of hematite nanoparticles. Finally, the magnetic properties confirmed from the VSM data revealed a significant decrease in the coercive field at 935 Oe, 610 Oe, and 548 Oe as the effect of citric acid concentration increased.
Tunable band-structures of MSe2/C3N (M = Mo and W) van der Waals Heterojunctions
Authors: Liu Zixiang , Yang Yaxiao , Yang Xiaoyu , Yin Guangqiang , Wang Zhiguo
Published: February 2023

Van der Waals (vdW) heterojunctions constructed using two-dimensional (2D) materials have shown excellent properties for applications in various fields. In this study, the structural and electronic properties of 2D MoSe2/C3N and WSe2/C3N vdW heterojunctions have been investigated using first-principles calculations. The results show that the MoSe2/C3N heterojunction is an indirect bandgap semiconductor with a small bandgap 0.05 eV and the WSe2/C3N heterojunction is a type II heterojunction with an indirect bandgap of 0.26 eV. Strains and external electric fields can effectively modulate the electronic structure of these heterojunctions. The WSe2/C3N heterojunction can become a type III heterojunction under compressive strains, which also becomes a direct bandgap heterojunction with type I band alignment under a negative electric field. Our results may be useful for the design of electronic nanodevices.
Invited Commentary: Modern Epidemiology Confronts COVID-19—Reflections From Psychiatric Epidemiology
Authors: Martínez-Alés Gonzalo , Keyes Katherine
Published: February 2023

Dimitris et al. (Am J Epidemiol. 2022;191(6):980–986) outline how the coronavirus disease 2019 (COVID-19) pandemic has, with mixed results, put epidemiology under the spotlight. While epidemiologic theory and methods have been critical in many successes, the ongoing global death toll from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the sometimes chaotic public messaging underscore that epidemiology as a field has room for improvement. Here, we use examples from psychiatric epidemiologic studies conducted during the COVID-19 era to reflect on errors driven by overlooking specific major methodological advances of modern epidemiology. We focus on: 1) use of nonrepresentative sampling in online surveys, which limits the potential knowledge to be gained from descriptive studies and amplifies collider stratification bias in causal studies; and 2) failure to acknowledge multiple versions of exposures (e.g., lockdown, school closure) and differences in prevalence of effect measure modifiers across contexts, which causes violations of the consistency assumption and lack of effect transportability. We finish by highlighting: 1) the heterogeneity of psychiatric epidemiologic results during the pandemic across place and sociodemographic groups and over time; 2) the importance of following the foundational advancements of modern epidemiology even in emergency settings; and 3) the need to limit the role of political agendas in cherry-picking and reporting epidemiologic evidence.
Heterogeneity of emotion regulation strategies in patients with alcohol use disorder during the first year of abstinence: a clustering analysis
Authors: Nandrino Jean-Louis , Gandolphe Marie-Charlotte , Claisse Caroline , Wawrziczny Emilie , Grynberg Delphine
Published: February 2023

Aims

Studies examining the use of specific emotion regulation (ER) strategies in patients with severe alcohol use disorder (AUD) are mainly focused on intergroup comparisons to the detriment of intragroup variability. Yet, these patients are in fact characterized by emotional deficits of varying severity, and we seek to identify different patterns of ER strategies in people with AUD during their first year of abstinence.

Methods

Based on the ER strategies used by a large sample of patients with AUD, we applied cluster analysis to identify the existence of subgroups using distinct patterns of adaptive and nonadaptive strategies. To characterize these groups, we compared their clinical characteristics and then their emotional regulation strategies to those of control consumers.

Results

A first cluster, representing 61% of the sample, is constituted by individuals with high adaptive strategy scores and high nonadaptive strategy scores; a second cluster, representing 39% of the sample, corresponds to individuals with low adaptive strategy scores and high nonadaptive strategy scores. The individuals in these two clusters differed in terms of anxiety level and abstinence time. Compared with control consumers, the use of nonadaptive ER strategies remained lower for the two clusters, while the use of adaptative strategies differed.

Conclusions

Our results support the idea of considering the heterogeneity of emotional capacities in individuals with AUD during the first year of abstinence. The identification of these profiles suggests either the existence of different adaptive ER capacities at baseline or a specific recovery of adaptive strategies over this period.
SARS-CoV-2 ORF8 dimerization and binding mode analysis with class I MHC: computational approaches to identify COVID-19 inhibitors
Authors: Selvaraj Chandrabose , Dinesh Dhurvas Chandrasekaran , Pedone Emilia Maria , Alothaim Abdulaziz S , Vijayakumar Rajendran , Rudhra Ondippili , Singh Sanjeev Kumar
Published: February 2023

SARS-CoV-2 encodes eight accessory proteins, one of which, ORF8, has a poorly conserved sequence with SARS-CoV and its role in viral pathogenicity has recently been identified. ORF8 in SARS-CoV-2 has a unique functional feature that allows it to form a dimer structure linked by a disulfide bridge between Cys20 and Cys20 (S-S). This study provides structural characterization of natural mutant variants as well as the identification of potential drug candidates capable of binding directly to the interchain disulfide bridge. The lead compounds reported in this work have a tendency to settle in the dimeric interfaces by direct interaction with the disulfide bridge. These molecules may disturb the dimer formation and may have an inhibition impact on its potential functional role in host immune evasion and virulence pathogenicity. This work provides detailed insights on the sequence and structural variability through computational mutational studies, as well as potent drug candidates with the ability to interrupt the intermolecular disulfide bridge formed between Cys20 and Cys20. Furthermore, the interactions of ORF8 peptides complexed with MHC-1 is studied, and the binding mode reveals that certain ORF8 peptides bind to MHC-1 in a manner similar to other viral peptides. Overall, this study is a narrative of various computational approaches used to provide detailed structural insights into SARS-CoV-2 ORF8 interchain disulfide bond disruptors.
Regularized adversarial learning for normalization of multi-batch untargeted metabolomics data
Authors: Dmitrenko Andrei , Reid Michelle , Zamboni Nicola
Published: February 2023

Motivation

Untargeted metabolomics by mass spectrometry is the method of choice for unbiased analysis of molecules in complex samples of biological, clinical or environmental relevance. The exceptional versatility and sensitivity of modern high-resolution instruments allows profiling of thousands of known and unknown molecules in parallel. Inter-batch differences constitute a common and unresolved problem in untargeted metabolomics, and hinder the analysis of multi-batch studies or the intercomparison of experiments.

Results

We present a new method, Regularized Adversarial Learning Preserving Similarity (RALPS), for the normalization of multi-batch untargeted metabolomics data. RALPS builds on deep adversarial learning with a three-term loss function that mitigates batch effects while preserving biological identity, spectral properties and coefficients of variation. Using two large metabolomics datasets, we showcase the superior performance of RALPS as compared with six state-of-the-art methods for batch correction. Further, we demonstrate that RALPS scales well, is robust, deals with missing values and can handle different experimental designs.

Availability and implementation

https://github.com/zamboni-lab/RALPS.

Supplementary information

Supplementary data are available at Bioinformatics online.
MeganServer: facilitating interactive access to metagenomic data on a server
Authors: Gautam Anupam , Zeng Wenhuan , Huson Daniel H
Published: February 2023

Motivation

Metagenomic projects often involve large numbers of large sequencing datasets (totaling hundreds of gigabytes of data). Thus, computational preprocessing and analysis are usually performed on a server. The results of such analyses are then usually explored interactively. One approach is to use MEGAN, an interactive program that allows analysis and comparison of metagenomic datasets. Previous releases have required that the user first download the computed data from the server, an increasingly time-consuming process. Here, we present MeganServer, a stand-alone program that serves MEGAN files to the web, using a RESTful API, facilitating interactive analysis in MEGAN, without requiring prior download of the data. We describe a number of different application scenarios.

Availability and implementation

MeganServer is provided as a stand-alone program tools/megan-server in the MEGAN software suite, available at https://software-ab.cs.uni-tuebingen.de/download/megan6. Source is available at: https://github.com/husonlab/megan-ce/tree/master/src/megan/ms.

Supplementary information

Supplementary data are available at Bioinformatics online.
‘You Say One Thing Wrong, and Your Children Are Gone’: Exploring Trauma-Informed Practices in Foster and Kinship Care
Authors: Cooper Kimberlea , Sadowski Christina , Townsend Rob
Published: February 2023

Trauma-informed care is a growing practice approach in child and family social work. Current policy directions in out-of-home care (OOHC) in Victoria, Australia show an interest in further implementation of trauma-informed care, particularly through training for foster and kinship carers. Drawing upon findings from grounded theory research with sixteen foster and kinship carers, this article considers the application of trauma-informed practices in home-based care in the Central Highlands region of Victoria, Australia. The research reveals that whilst carers utilise principles of trauma-informed care to support children and young people, they do not always experience trauma-informed support from the wider OOHC system. This discrepancy suggests that the implementation of trauma-informed care has the potential to increase pressure on home-based carers if it is only encouraged at the interpersonal level between carers and children, without incorporating associated systems-level change. These findings propose that whilst micro-level support and training for carers are necessary and useful, it is crucial for OOHC systems to move beyond such initiatives to plan and enact macro-level reforms.
Cell therapies for spinal cord injury: a review of the clinical trials and cell-type therapeutic potential
Authors: Ribeiro Beatriz F , da Cruz Bruna C , de Sousa Bárbara M , Correia Patrícia D , David Nuno , Rocha Camila , Almeida Ramiro D , Ribeiro da Cunha Maria , Marques Baptista António A , Vieira Sandra I
Published: February 2023

Spinal cord injury (SCI) is an as yet untreatable neuropathology that causes severe dysfunction and disability. Cell-based therapies hold neuroregenerative and neuroprotective potential, but, although being studied in SCI patients for more than two decades, long-term efficacy and safety remain unproven, and which cell types result in higher neurological and functional recovery remains under debate.

In a comprehensive scoping review of 142 reports and registries of SCI cell-based clinical trials, we addressed the current therapeutical trends and critically analysed the strengths and limitations of the studies. Schwann cells, olfactory ensheathing cells (OECs), macrophages and various types of stem cells have been tested, as well as combinations of these and other cells. A comparative analysis between the reported outcomes of each cell type was performed, according to gold-standard efficacy outcome measures like the ASIA impairment scale, motor and sensory scores.

Most of the trials were in the early phases of clinical development (phase I/II), involved patients with complete chronic injuries of traumatic aetiology and did not display a randomized comparative control arm. Bone marrow stem cells and OECs were the most commonly tested cells, while open surgery and injection were the main methods of delivering cells into the spinal cord or submeningeal spaces. Transplantation of support cells, such as OECs and Schwann cells, resulted in the highest ASIA Impairment Scale (AIS) grade conversion rates (improvements in ∼40% of transplanted patients), which surpassed the spontaneous improvement rate expected for complete chronic SCI patients within 1 year post-injury (5–20%). Some stem cells, such as peripheral blood-isolated and neural stem cells, offer potential for improving patient recovery. Complementary treatments, particularly post-transplantation rehabilitation regimes, may contribute highly to neurological and functional recovery.

However, unbiased comparisons between the tested therapies are difficult to draw, given the great heterogeneity of the design and outcome measures used in the SCI cell-based clinical trials and how these are reported. It is therefore crucial to standardize these trials when aiming for higher value clinical evidence-based conclusions.