bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of the magnetic field on properties of hot electron emission from ablative plasma produced at laser irradiation of a disc-coil target
Authors: Pisarczyk T , Renner O , Dudzak R , Chodukowski T , Rusiniak Z , Domanski J , Badziak J , Dostal J , Krupka M , Singh S , Klir D , Ehret M , Gajdos P , Zaras-Szydłowska A , Rosinski M , Tchórz P , Szymanski M , Krasa J , Burian T , Pfeifer M , Cikhardt J , Jelinek S , Kocourkova G , Batani D , Batani K , Santos J , Vlachos C , Ospina-Bohórquez V , Volpe L , Borodziuk S , Krus M , Juha L
Published: September 2022

Optical generators of strong magnetic fields based on the laser-driven-coil target concept are considered to be useful tools for studies of magnetized plasmas in particular, for the study of implosion of magnetized fusion targets in inertial fusion research and astrophysical applications. This paper presents the results of the research directed at an investigation of the plasma properties in a laser-induced magnetic field. In the experiment carried out on the kilojoule PALS laser facility, a generator of the magnetic field was a disc-coil (DC) target composed of a Cu disk coupled to a single-turn coil irradiated by a 1ω laser beam with an energy of 500 J. The attention was focused on examining the influence of the magnetic field on properties of the hot electron (HE) flux emitted from the front surface of the irradiated target. The three-frame complex interferometry and four-frame x-ray camera combined with the measurements of the HE population and energy using a multi-channel magnetic electron spectrometer and 2D-resolved imaging of the induced Cu Kα line emission were applied to characterize the ablative plasma and the generated particles. Based on the measured angular distributions of the electron energy spectra, 3D simulations have been performed to visualize the effect of the magnetic field on the HE flux and to provide information on space-time distribution of the electron and current density both without and with the presence of an axial magnetic field. The obtained results confirmed the possibility of generating magnetic fields above 5 T using the proposed DC target design as well as the significant impact of these fields on properties of the ablative plasma and the HE emission.
Dispersion relation and instability for an anisotropic nonuniform flowing plasma
Authors: Lee Min Uk , Yun Gunsu S , Ji Jeong-Young
Published: September 2022

A generalized formula for wave instability is developed for an anisotropic nonuniform plasma with finite flows and temperatures. Six-moment fluid equations are solved to give the analytic expression for wave instability in arbitrarily nonuniform plasmas. The analytic formula explicitly states the dependence of wave instability on the nonuniformities of number density, flow velocity, and anisotropic or isotropic pressure. The accuracy of the formalism is verified by a numerical calculation of implicit dispersion relations in complex Fourier space. The analysis shows that nonuniformity plays a critical role in plasma instability, while the flow velocity and anisotropic pressures determine the growth rate of the instability. The instability diagram and associated instability criterion for anisotropy-driven instability are introduced as applications of the formalism.
Experimental investigation on streamer inception from artificial hydrometeors
Authors: Mirpour S , Nijdam S
Published: September 2022

In this study we use an experimental investigation to shed light on the lightning inception problem. From atmospheric observations, it is known that the electric fields in thunderclouds are significantly lower than required for electric breakdown in air. One theory to explain lightning inception is that hydrometeors, i.e. any liquid or solid water particles formed in the atmosphere, greatly enhance the local electric field and can thereby initiate an electron avalanche leading to a streamer discharge. In this study, we investigate streamer initiation in the presence of artificial particles with different shapes. A metal or dielectric (TiO2) particle is suspended between a high-voltage and a grounded planar electrode which are separated by 16 cm in 50 mbar air. The particles are shaped as ellipsoids with a length of 8, 4, 2, and 1 cm and with different aspect ratios. A negative high voltage pulse is applied with a rise time of 30 ns, a pulse width of 1–10 μs, a repetition rate of 1 Hz, and a maximum voltage between 1 and 50 kV. Results show that the required background electric field for breakdown in the presence of a dielectric particle is decreased to 0.4 times the air breakdown field. Moreover, we observed bipolar streamer development from the particles where negative streamers are thicker and slightly slower than positive streamers. Finally, we found that streamers from longer particles are thicker and faster.
Expansion of surface barrier discharge scrutinized
Authors: Lindner M , Pipa A V , Brandenburg R , Schreiner R
Published: September 2022

Developing the fundamentals for the electrical diagnostics of surface dielectric barrier discharges (SDBDs) is of enormous importance for several applications, for example flow control and gas cleaning. The main challenge is to account for the discharge expansion along the dielectric surface. Typically, a linear expansion with the amplitude of the applied voltage is observed. In this work, we report on a step-wise SDBD expansion along the Al2O3 dielectric surface. More specific, the discharge occupied a certain area after ignition, which remained constant until the voltage exceeded the critical amplitude V

L
. This absence of expansion is seen as a linear dependence of the discharge power on the applied voltage and it was additionally confirmed by photographs with long exposure times. This novel phenomenon is more pronounced for thicker dielectrics. It is suggested that the derivative of the charge–voltage characteristics can be used for the determination of all essential parameters of the simplest equivalent circuit of SDBDs. Moreover, it was shown that the derivative of the charge–voltage characteristics for the positive half-cycle of the discharge agrees numerically with the voltage dependence of the reactor capacitance derived from photographs. This agreement between both measurement methods indicate a similar step-wise expansion of the SDBD even if a voltage amplitude above V

L
is applied
Splitting of ionization waves at the edge of a dielectric plate oriented at grazing angles between the helium plasma jet and the plate
Authors: Babaeva Natalia Yu , Naidis George V
Published: September 2022

In this paper, we discuss the results from the two-dimensional computational investigation of the effects of a helium plasma jet interacting with a dielectric plate at a floating potential. The plate is oriented at grazing angles formed between the plasma plume and the plate. We show that for angles α > 70° the jet plasma envelopes the plate and the splitting of an ionization wave (IW) at its edge is observed. As a result, one of the IWs propagates at some elevation over the upper surface of the plate. The other IW slides along the bottom surface as a surface discharge. This effect is partially attributed to the electric field direction and buoyancy forces which are especially important for the light helium channel surrounded by air. As such, the treatment of the top and bottom surfaces is not identical even for the horizontally oriented plate (α = 90°). We discuss the production and delivery to the plate surfaces the charged and neutral species important for applications. For the conditions considered, both sides of the plate are treated simultaneously. We also show that the buoyancy forces affect the reactive oxygen and nitrogen species distributions. For the helium jet which bends upward due to these forces, the best results for simultaneous treatment of thin plates can be achieved at grazing angles α = 80°–83°, but not at the angle of 90°. The choice of these particular incidence angles can provide better results. Locating the plate horizontally in parallel to the plasma jet axis can be dis-advantageous.
On the validity of the classical plasma conductivity in capacitive RF discharges
Authors: Wang Li , Vass Máté , Lafleur Trevor , Donkó Zoltán , Song Yuan-Hong , Schulze Julian
Published: September 2022

The plasma conductivity is an important input parameter for various plasma models. It is typically obtained from a simplified version of the electron momentum balance equation, where only a single inertia term and a simplified description of the collisional momentum transfer are included. The electric field is assumed to be a harmonic function of the driving frequency, higher harmonics of the current and spatial variations are neglected. Through particle-in-cell/Monte Carlo collision (PIC/MCC) simulations and analysis of the electric field generation based on velocity moments of the Boltzmann equation, the validity of this classical model is studied in capacitively coupled plasmas (CCPs). We find that these assumptions/simplifications result in significant inaccuracies of the conductivity in many cases. In single frequency CCPs, a deviation of more than an order of magnitude from the effective PIC-conductivity obtained from the simulations is found at low pressures in the discharge center and at the maximum sheath edge. In the center, this deviation is caused by neglecting the temperature gradient term in the momentum balance equation and adopting an approximation of the Ohmic term in the classical model, while at the maximum sheath edge it is induced by neglecting the density gradient term that accounts for the effect of the ambipolar electric field. The inaccuracy in the discharge center is reduced at higher pressures where the Ohmic term dominates and the approximations made in the classical model are more applicable. Better performance of the classical model is also found under conditions at which the inertia term included in the model plays an important role. Generally, neglecting higher harmonics of the current and spatial variations of plasma parameters is found to cause strong inaccuracies. Thus, the classical model can result in an inaccurate calculation of the power absorbed by electrons. Our results indicate that its applicability must be evaluated for a given set of conditions before using it to avoid introducing errors to plasma models.
Optimal design and experimental validation of 3D printed soft pneumatic actuators
Authors: Lu Yifu , Tong Liyong
Published: September 2022

This study develops a novel design of a unit cell-based bending-type soft pneumatic actuator, and formulates the design problem as compliant mechanisms under design-dependent pressure loadings. The proposed design is first optimized by using a topology optimization algorithm, in which the design-dependent loads and fluid-structure interface are tracked and formulated via finite element based approaches. Then, to validate the optimized design, it is modeled numerically using finite element analysis (FEA) and compared with the non-optimized traditional rectangular design. The optimal design can provide 19.5% improvements in bending angle. In addition, the proposed optimal design is prototyped using 3D printing. The prepared single actuator specimens are tested under pneumatic pressure, and the measured deformations are compared with those obtained from FEA. The results reveal that the optimized design can undergo large and compliant deformations under pneumatic pressure and generate a full (

360
∘

) bending. Furthermore, multiple actuator specimens of the proposed design are also assembled and integrated to prototype soft pneumatic grippers, with which several grasping tests are conducted. The adaptability and compatibility of the soft gripper are verified via gripping a wide range of irregular, soft, and fragile objects.
Energy exchange dependent transient ferromagnetic like state of ultrafast magnetization dynamics
Authors: Gao Shihan , Liu Donglin , Zheng Taotao , Ostler Thomas , Chantrell Roy , Xu Chudong
Published: September 2022

The study of laser-induced ultrafast magnetization dynamics is crucial for the development of information recording technology. Due to the complex mechanism, there is still a lack of comprehensive understanding for ultrafast magnetization dynamics. As an essential stage of laser-induced ultrafast magnetization switching process, the transient ferromagnetic like state (TFLS), has attracted much attention. Different from other studies on TFLS through the difference of magnetization dynamics between rare-earth and transition-metal, our study mainly focuses on the influence of energy injection and relaxation on TFLS in the process of ultrafast magnetization dynamics. The influence of various parameters on the formation of energy exchange dependent TFLS is studied. The results of simulation well support our view. Understanding the mechanism behind the TFLS is of great significance to promote the application of laser-induced ultrafast magnetization switching.
Design a new image encryption algorithm based on a 2D-ASCC map
Authors: Fei Xiaoyu , Zhang Jiujun , Qin Wenjie
Published: September 2022

In this paper, a new model of 2D absolute sine-cosine coupling (2D-ASCC) is proposed. In comparison with other 2D chaos map, the proposed system has higher complexity and better property of pseudo-random. It can effectively improve the security performance of encryption algorithm, if the proposed chaos map is applied in the design of image encryption algorithm based on chaos. Then, a new diffusion algorithm is designed based on the jumping diffusion. The plaintext is divided into two groups, and each group of plaintext is encrypted with a different formula. The pixel value of each ciphertext is composed of several non-adjacent pixels and the pseudo-random values generated by the proposed chaos map. In comparison with some existing encryption scheme, by using the design encryption scheme, the plaintext image can be completely encrypted in one iteration, it can significantly increase the security of algorithm and reduces the correlation between adjacent pixels. Finally, by using the numerical simulation and the security analysis, the effectiveness of the encryption algorithm is verified, and the comparison results show the higher security of the design encryption algorithm.
The SparSpec algorithm and the application to the detection of spatial periodicities in tokamaks: from a 1D to a 2D analysis
Authors: Testa D , Charrière J
Published: September 2022

A well-known, previously only 1D, algorithm using the Sparse Representation of Signals and an iterative Block Coordinate Descent method (the SparSpec-1D algorithm) has been further developed and tested in a 2D spatial domain to obtain the toroidal and poloidal periodicities of magnetic fluctuations in a tokamak. The tests are performed essentially using simulated data, because we know what the answer must be, and therefore it is straightforward to verify the accuracy of the algorithm. Two more examples using actual data from the JET and TCV tokamaks are considered to test the algorithm in real-life experiments; a further example using simulated data constructed from nominal test cases for the forthcoming ITER tokamak is also considered. The CPU run-time and the precision of the SparSpec-2D algorithm are studied as function of different analysis parameters. The stability of the algorithm is also tested via the introduction of random errors in the input signal. We find that the spatial-2D version of the baseline SparSpec-1D algorithm accurately finds the modes in the 2D toroidal and poloidal space, provided the set of magnetic sensors used for the analysis do not have a (quasi-)ignorable coordinate. The number of probes and their position are the key parameters that must be optimized for finding correct solutions. The main difficulty, as for the baseline SparSpec-1D algorithm, lies in dealing correctly with the intrinsic measurement uncertainties associated to the input magnetic fluctuation data, particularly the phase error, and this has been already separately reported in a companion work. However, the required CPU run-time for SparSpec-2D is significantly longer than that needed for 2 × SparSpec-1D, and thus SparSpec-2D is effectively suitable for use only when the 2 × 1D analyses cannot provide accurate results, which is the case when the set of measurements does not have an ignorable coordinate.
The influence of aluminum’s crystalline structure on the elastic, dielectric, and electrical properties of Ni ferrite
Authors: Arrasheed Enas A , Alibwaini Yamen A , Meaz T M , Ajlouni Abdul-Wali , Shalaby R M , Hemeda O M , Henaish A M A
Published: September 2022

The authors investigate the effect of Al on the structural, elastic, and electrical properties of a Ni nano ferrite. Six samples of NiAl

x

Fe
2−x
O
4 (where x = 0.00, 0.20, 0.40, 0.60, 0.80, and 1.00) were synthesized using flash auto combustion. As shown in XRD patterns, the lattice appears as a Fd-3m space group, a single-phase spinel structure with average crystallite size ranging from 22.4–24.7 nm for all samples. SEM and TEM images showed a uniform and spherical structural with a narrow size distribution. The results manifest significant changes in the elastic and electrical properties due to the presence of Al. As Al content increased, the bulk B, shear G, and Young E moduli decreased and remained in the same order of hundreds in the GPa range: however, the values of the Debye temperature θ

D
increased. The dielectric parameters ε′, ε″, and tan δ decreased as the frequency of the applied field and Al content increased: they also decreased as temperature increased. The relaxation times were

τ

ε

=

τ

tan

δ

=
0.1959

μ
s

for all samples. The electric moduli M′ and M″ increased as the frequency of the applied field and Al content increased, but they decreased as temperature increased. The relaxation times are dispersed depending on Al content, frequency, and temperature. The Cole-Cole curve showed two semicircles corresponding to the grain and grain boundary with the electrical relaxation of the non-Debye form. The electric impedance Z′ and Z″ increased as the frequency of the applied field and temperature increased, although they decreased as Al content increased. These results indicate that Ni-Al ferrite has respectable dielectric properties, which opens the door for many applications in control and safety monitoring tools, where dynamic process temperature sensors are of great importance and the temperature dependency of the material is significant.
PBH assisted search for QCD axion dark matter
Authors: Choi Gongjun , Schiappacasse Enrico D.
Published: September 2022

The entropy production prior to BBN era is one of ways to prevent QCD axion with the decay constant Fa
∈ [1012 GeV, 1016 GeV] from overclosing the universe when the misalignment angle is θ
i = 𝒪(1). As such, it is necessarily accompanied by an early matter-dominated era (EMD) provided the entropy production is achieved via the decay of a heavy particle. In this work, we consider the possibility of formation of primordial black holes during the EMD era with the assumption of the enhanced primordial scalar perturbation on small scales (k > 104 Mpc-1). In such a scenario, it is expected that PBHs with axion halo accretion develop to ultracompact minihalos (UCMHs). We study how UCMHs so obtained could be of great use in the experimental search for QCD axion dark matter with Fa
∈ [1012 GeV, 1016 GeV].
Constraints on the mass and self-coupling of ultra-light scalar field dark matter using observational limits on galactic central mass
Authors: Chakrabarti Sayan , Dave Bihag , Dutta Koushik , Goswami Gaurav
Published: September 2022

It is well known that Ultra-Light Dark Matter (ULDM), usually scalar fields of massm∼ 10-22eV, can solve some of the outstanding problems of the Cold Dark Matter (CDM) paradigm. Such a scalar field could have non-negligible self-couplingλ. In this work, using the known observational upper limit on the amount of centrally concentrated dark matter in a galaxy, we arrive at the observational constraints in theλ-m(self coupling-mass) parameter space. It is found that the observational limit on the mass m of the ULDM depends upon the sign and strength of the self-interactions. We demonstrate that, form∼ 10-22eV, self-coupling values of 𝒪(10-96) (corresponding to a scattering length ofas∼ 10-82m) can be probed using limits on the dark matter mass within 10 pc of the centre of M87 galaxy. Our analysis suggests that if Ultra Light Axion particles (ULAs) form all of dark matter, dark matter particle mass must be less than  ∼ 6 × 10-23eV.
Weak gravity conjecture from conformal field theory: a challenge from hyperscaling violating and Kerr-Newman-AdS black holes
Authors: Sadeghi Jafar , Shokri Mehdi , Alipour Mohammad Reza , Gashti Saeed Noori
Published: September 2022

We search for a possible relationship between weak gravity conjecture (WGC) and conformal field theory (CFT) in hyperscaling violating and Kerr-Newman-AdS black holes. We deal with the critical points of the black hole systems using the correlation function introduced in CFT and discuss WGC conditions using the imaginary part of the energy obtained from the critical points and their poles. Under the assumptions

,

, and

, we link WGC to hyperscaling violating black holes owing to the existence of

values larger and smaller than one. For the second black hole system, we study the conditions of WGC for Kerr-Newman-AdS black holes using rotation and radius parameters. Then, we show that the conditions of WGC are satisfied when the charged particle near the hyperscaling violating and Kerr-Newman black holes is

with a ratio

.
Isotope effects under the influence of global radial electric fields in a helical configuration
Authors: Moritaka T. , Sugama H. , Cole M.D.J. , Hager R. , Ku S. , Chang C.S. , Ishiguro S.
Published: September 2022

Isotope effects under the influence of a radial electric field are examined in a helical magnetic field configuration. We perform global gyrokinetic simulations with additional poloidal rotations to estimate quasi-linear heat flux due to ion temperature gradient mode under the mixing length model. In single-ion-species plasmas, the mass number dependency of heat flux agrees with gyro-Bohm scaling in the absence of a radial electric field. Favorable mass number dependencies violating gyro-Bohm scaling are observed in the presence of a global radial electric field or a heavy hydrogen component in multi-ion-species plasmas. The radial electric field and the heavy hydrogen component affect the heat flux through an increase of wavelength as well as mode stabilization. Poloidal Mach number characterizes the transition from unfavorable to favorable mass number dependency under radial electric fields. While the heat flux is independent of mass number for a given poloidal Mach number, the heat flux decreases for higher mass numbers in a given radial electric field. The heat flux is also independent of average mass number in multi-ion-species plasmas because the heavy hydrogen component effectively enhances the light hydrogen heat flux. The present results are potentially relevant to the violation of gyro-Bohm scaling observed in the recent deuterium experiments in the Large Helical Device.
Effect of Cu substitution on anion redox behaviour in P3-type sodium manganese oxides
Authors: Linnell Stephanie F , Manche Alexis G , Liao Yingling , Hirsbrunner Moritz , Imada Saki , Naden Aaron B , Irvine John T S , Duda Laurent C , Armstrong A Robert
Published: September 2022

Sodium layered oxides which display oxygen anion redox behaviour are considered promising positive electrodes for sodium-ion batteries because they offer increased specific capacities. However, they suffer from irreversible structural changes resulting in significant capacity loss and limited oxygen redox reversibility. Here the effect of Cu substitution on the electrochemical performance of P3-type sodium manganese oxide is examined by evaluating the structural and electronic structural evolution upon cycling, supported by density functional theory (DFT) calculations. Over the voltage range 1.8–3.8 V vs. Na/Na+, where the redox reactions of the transition metal ions contribute entirely towards the charge compensation mechanism, stable cycling performance is maintained, showing a capacity retention of 90% of the initial discharge capacity of 166 mA h g−1 after 40 cycles at 10 mA g−1. Over an extended voltage range of 1.8–4.3 V vs. Na/Na+, oxygen anion redox is invoked, with a voltage hysteresis of 110 mV and a greater initial discharge capacity of 195 mA h g−1 at 10 mA g−1 is reached. Ex-situ powder x-ray diffraction patterns reveal distortion of the P3 structure to P′3 after charge to 4.3 V, and then transformation to O′3 upon discharge to 1.8 V, which contributes towards the capacity fade observed between the voltage range 1.8–4.3 V. DFT with projected density of states calculations reveal a strong covalency between the copper and oxygen atoms which facilitate both the cationic and anionic redox reactions in P3-type Na0.67Mn0.9Cu0.1O2.
Prediction of malignant transformation in oral epithelial dysplasia using machine learning
Authors: Ingham James , Smith Caroline I , Ellis Barnaby G , Whitley Conor A , Triantafyllou Asterios , Gunning Philip J , Barrett Steve D , Gardener Peter , Shaw Richard J , Risk Janet M , Weightman Peter
Published: September 2022

A machine learning algorithm (MLA) has been applied to a Fourier transform infrared spectroscopy (FTIR) dataset previously analysed with a principal component analysis (PCA) linear discriminant analysis (LDA) model. This comparison has confirmed the robustness of FTIR as a prognostic tool for oral epithelial dysplasia (OED). The MLA is able to predict malignancy with a sensitivity of 84 ± 3% and a specificity of 79 ± 3%. It provides key wavenumbers that will be important for the development of devices that can be used for improved prognosis of OED.
Countably compact groups having minimal infinite powers
Authors: Dikranjan Dikran , Uspenskij Vladimir
Published: September 2022

We answer the question, raised more than thirty years ago by Dikranjan and Shakhmatov [Comp. Rend. Acad. Sci. Bulg., 41 (1990), pp. 13-15] and Dikranjan and Shakhmatov [Trans. Amer. Math. Soc. 335 (1993), pp. 775-790], on whether the power

G
ω

G^\omega

of a countably compact minimal Abelian group

G
G

is minimal, by showing that the negative answer is equivalent to the existence of measurable cardinals. The proof is carried out in the larger class of sequentially complete groups. We characterize the sequentially complete minimal Abelian groups

G
G

such that

G
ω

G^\omega

is minimal – these are exactly those

G
G

that contain the connected component of their completion. This naturally leads to the next step, namely, a better understanding of the structure of the sequentially complete minimal Abelian groups, and in particular, their connected components which turns out to depend on the existence of Ulam measurable cardinals. More specifically, all connected sequentially complete minimal Abelian groups are compact if Ulam measurable cardinals do not exist. On the other hand, for every Ulam measurable cardinal

σ
\sigma

we build a non-compact torsion-free connected minimal

ω
\omega

-bounded Abelian group of weight

σ
\sigma

, thereby showing that the Ulam measurable cardinals are precisely the weights of non-compact sequentially complete connected minimal Abelian groups.
Norm attaining Lipschitz maps toward vectors
Authors: Choi Geunsu
Published: September 2022

We characterize the norm attainment toward vectors for vector-valued Lipschitz maps defined on a general metric space. The main theorem of the present paper states that on a large class of metric spaces including infinite subsets of finite-dimensional spaces, every Lipschitz map attains its norm toward a vector if and only if the range space is finite-dimensional. Furthermore, motivated by the first negative example given by G. Godefroy, some denseness results for norm attaining Lipschitz maps toward vectors are also presented.
Metabolic rate shapes differences in foraging efficiency among honeybee foragers
Authors: Cassano Julian , Naug Dhruba
Published: September 2022

Metabolic rate is the rate at which organisms process energy and is often considered as the fundamental driver of life history processes. The link between metabolic rate and life history is critically mediated via foraging, which shapes the energy acquisition patterns of an individual. This predicts that individuals with different metabolic rates likely vary in their foraging strategies, although such a link has rarely been empirically investigated in the context of optimal foraging theory—a powerful framework for understanding how animals maximize their foraging returns. Many central place foragers such as honeybees maximize their energetic efficiency rather than the rate of energetic gain, given the critical role of energetic costs in foraging decisions. We therefore tested if individuals with low and high metabolic rates differ in efficiency maximization, using genetic lines of honeybees with different metabolic rates. Our results show that low metabolic rate foragers visit more flowers during a foraging trip and have a higher energetic efficiency than high metabolic rate foragers in both low and high resource conditions. We discuss the significance of these results in the context of division of labor and the adaptive role of phenotypic diversity in metabolic rate in a social insect colony.
HiHi fMRI: a data-reordering method for measuring the hemodynamic response of the brain with high temporal resolution and high SNR
Authors: Nagy Zoltan , Hutton Chloe , David Gergely , Hinterholzer Natalie , Deichmann Ralf , Weiskopf Nikolaus , Vannesjo S Johanna
Published: September 2022

There is emerging evidence that sampling the blood-oxygen-level-dependent (BOLD) response with high temporal resolution opens up new avenues to study the in vivo functioning of the human brain with functional magnetic resonance imaging. Because the speed of sampling and the signal level are intrinsically connected in magnetic resonance imaging via the T1 relaxation time, optimization efforts usually must make a trade-off to increase the temporal sampling rate at the cost of the signal level. We present a method, which combines a sparse event-related stimulus paradigm with subsequent data reshuffling to achieve high temporal resolution while maintaining high signal levels (HiHi). The proof-of-principle is presented by separately measuring the single-voxel time course of the BOLD response in both the primary visual and primary motor cortices with 100-ms temporal resolution.
Altered synaptic protein expression, aberrant spine morphology, and impaired spatial memory inDlgap2mutant mice, a genetic model of autism spectrum disorder
Authors: Hsieh Ming-Yen , Tuan Li-Heng , Chang Ho-Ching , Wang Yu-Chun , Chen Chia-Hsiang , Shy Horng-Tzer , Lee Li-Jen , Gau Susan Shur-Fen
Published: September 2022

A microdeletion of approximately 2.4 Mb at the 8p23 terminal region has been identified in a Taiwanese autistic boy. Among the products transcribed/translated from genes mapped in this region, the reduction of DLGAP2, a postsynaptic scaffold protein, might be involved in the pathogenesis of autism spectrum disorder (ASD). DLGAP2 protein was detected in the hippocampus yet abolished in homozygous Dlgap2 knockout (Dlgap2 KO) mice. In this study, we characterized the hippocampal phenotypes in Dlgap2 mutant mice. Dlgap2 KO mice exhibited impaired spatial memory, indicating poor hippocampal function in the absence of DLGAP2. Aberrant expressions of postsynaptic proteins, including PSD95, SHANK3, HOMER1, GluN2A, GluR2, mGluR1, mGluR5, βCAMKII, ERK1/2, ARC, BDNF, were noticed in Dlgap2 mutant mice. Further, the spine density was increased in Dlgap2 KO mice, while the ratio of mushroom-type spines was decreased. We also observed a thinner postsynaptic density thickness in Dlgap2 KO mice at the ultrastructural level. These structural changes found in the hippocampus of Dlgap2 KO mice might be linked to impaired hippocampus-related cognitive functions such as spatial memory. Mice with Dlgap2 deficiency, showing signs of intellectual disability, a common co-occurring condition in patients with ASD, could be a promising animal model which may advance our understanding of ASD.
Differences and commonalities in the genetic architecture of protein quantitative trait loci in European and Arab populations
Authors: Thareja Gaurav , Belkadi Aziz , Arnold Matthias , Albagha Omar M E , Graumann Johannes , Schmidt Frank , Grallert Harald , Peters Annette , Gieger Christian , Consortium The Qatar Genome Program Research , Suhre Karsten
Published: September 2022

Polygenic scores (PGS) can identify individuals at risk of adverse health events and guide genetics-based personalized medicine. However, it is not clear how well PGS translate between different populations, limiting their application to well-studied ethnicities. Proteins are intermediate traits linking genetic predisposition and environmental factors to disease, with numerous blood circulating protein levels representing functional readouts of disease-related processes. We hypothesized that studying the genetic architecture of a comprehensive set of blood-circulating proteins between a European and an Arab population could shed fresh light on the translatability of PGS to understudied populations. We therefore conducted a genome-wide association study with whole-genome sequencing data using 1301 proteins measured on the SOMAscan aptamer-based affinity proteomics platform in 2935 samples of Qatar Biobank and evaluated the replication of protein quantitative traits (pQTLs) from European studies in an Arab population. Then, we investigated the colocalization of shared pQTL signals between the two populations. Finally, we compared the performance of protein PGS derived from a Caucasian population in a European and an Arab cohort. We found that the majority of shared pQTL signals (81.8%) colocalized between both populations. About one-third of the genetic protein heritability was explained by protein PGS derived from a European cohort, with protein PGS performing ~20% better in Europeans when compared to Arabs. Our results are relevant for the translation of PGS to non-Caucasian populations, as well as for future efforts to extend genetic research to understudied populations.
Augmenting mitral valve repair evaluation with intraoperative left ventricle pressure measurements
Authors: Issa Hugo , Deng Mimi , Rahmouni Kenza , Chan Vincent
Published: September 2022

Surgical mitral valve repair remains the gold standard treatment of mitral regurgitation due to degenerative disease. Surgery is performed on the quiescent heart; therefore, assessments of valve repair success can only be made following separation from cardiopulmonary bypass. Intra-ventricular pressure measurements are often made in percutaneous valve procedures but has yet been described at the time of surgical repair. As an example, the saline test, whereby normal saline is injected across the mitral valve from the left atrium into the left ventricle, on the arrested heart remains an integral component of surgical repair. However, the haemodynamics of the saline test have never been evaluated. We present a simple and novel technique to quantify the saline test by passing a 22-G catheter across the mitral leaflets during saline testing under maximal ventricle distension. The saline test may be less informative among patients in whom the maximum generated left ventricle diastolic pressure is low. These data may be of help to a surgeon interpreting intraoperative saline tests with the hope of a competent mitral valve. As well, it may provide support for intraventricular pressure monitoring at the time of mitral valve surgery.
Gradient Estimate for the Heat Kernel on Some Fractal-Like Cable Systems and Quasi-Riesz Transforms
Authors: Devyver Baptiste , Russ Emmanuel , Yang Meng
Published: September 2022

We give pointwise upper estimate for the gradient of the heat kernel on some fractal-like cable systems including the Vicsek and the Sierpiński cable systems. Applications to $L^{p}$-boundedness of quasi-Riesz transforms are derived.
CFD analysis of phase-change material-based heat storage with dimple-shaped fins: evaluation of fin configuration and distribution pattern
Authors: Khedher Nidhal Ben , Mahdi Jasim M , Majdi Hasan S , Khosravi Koorosh , Al-Azzawi Waleed Khalid , Al-Qrimli Fadhil Abbas , Dhahbi Sami , Talebizadehsardari Pouyan
Published: September 2022

Phase-change materials (PCMs) have a remarkable potential for use as efficient energy storage means. However, their poor response rates during energy storage and retrieval modes require the use of heat transfer enhancers to combat these limitations. This research marks the first attempt to explore the potential of dimple-shaped fins for the enhancement of PCM thermal response in a shell-and-tube casing. Fin arrays with different dimensions and diverse distribution patterns were designed and studied to assess the effect of modifying the fin geometric parameters and distribution patterns in various spatial zones of the physical domain. The results indicate that increasing the number of dimple fins in the range of 8–32 results in faster heat storage rates by up to 8.7% faster than they would be without the dimple fins. Further improvements of approximately 1.4, 1.2, 1.1, and 1.0% can be obtained by optimizing the position of the first fin section, the spacing between other fin sections, the fin spacing based on the aromatic algorithm, and the use of the staggered fin distribution. The heat storage rate is improved by almost 12% for the best case compared with that of the no-fin case.
Do people learn about politics on social media? A meta-analysis of 76 studies
Authors: Amsalem Eran , Zoizner Alon
Published: September 2022

Citizens turn increasingly to social media to get their political information. However, it is currently unclear whether using these platforms actually makes them more politically knowledgeable. While some researchers claim that social media play a critical role in the learning of political information within the modern media environment, others posit that the great potential for learning about politics on social media is rarely fulfilled. The current study tests which of these conflicting theoretical claims is supported by the existing empirical literature. A preregistered meta-analysis of 76 studies (N = 442,136) reveals no evidence of any political learning on social media in observational studies, and statistically significant but substantively small increases in knowledge in experiments. These small-to-nonexistent knowledge gains are observed across social media platforms, types of knowledge, countries, and periods. Our findings suggest that the contribution of social media toward a more politically informed citizenry is minimal.
Organelles and phytohormones: a network of interactions in plant stress responses
Authors: Bittner Andras , Cieśla Agata , Gruden Kristina , Lukan Tjaša , Mahmud Sakil , Teige Markus , Vothknecht Ute C , Wurzinger Bernhard
Published: September 2022

Phytohormones are major signaling components that contribute to nearly all aspects of plant life. They constitute an interconnected communication network to fine-tune growth and development in response to the ever-changing environment. To this end, they have to coordinate with other signaling components, such as reactive oxygen species and calcium signals. On the one hand, the two endosymbiotic organelles, plastids and mitochondria, control various aspects of phytohormone signaling and harbor important steps of hormone precursor biosynthesis. On the other hand, phytohormones have feedback actions on organellar functions. In addition, organelles and phytohormones often act in parallel in a coordinated matter to regulate cellular functions. Therefore, linking organelle functions with increasing knowledge of phytohormone biosynthesis, perception, and signaling will reveal new aspects of plant stress tolerance. In this review, we highlight recent work on organelle–phytohormone interactions focusing on the major stress-related hormones abscisic acid, jasmonates, salicylic acid, and ethylene.
Plant transcripts with long or structured upstream open reading frames in theNDL25ʹ UTR can escape nonsense-mediated mRNA decay in a reinitiation-independent manner
Authors: Cymerman Miryam A , Saul Helen , Farhi Ronit , Vexler Karina , Gottlieb Dror , Berezin Irina , Shaul Orit
Published: September 2022

Many eukaryotic transcripts contain upstream open reading frames (uORFs). Translated uORFs can inhibit the translation of main ORFs by imposing the need for reinitiation of translation. Translated uORFs can also lead to transcript degradation by the nonsense-mediated mRNA decay (NMD) pathway. In mammalian cells, translated uORFs were shown to target their transcripts to NMD if the uORFs were long (>23–32 amino acids), structured, or inhibit reinitiation. Reinitiation was shown to rescue uORF-containing mammalian transcripts from NMD. Much less is known about the significance of the length, structure, and reinitiation efficiency of translated uORFs for NMD targeting in plants. Although high-throughput studies suggested that uORFs do not globally reduce plant transcript abundance, it was not clear whether this was due to NMD-escape-permitting parameters of uORF recognition, length, structure, or reinitiation efficiency. We expressed in Arabidopsis reporter genes that included NDL2 5ʹ untranslated region and various uORFs with modulation of the above parameters. We found that transcripts can escape NMD in plants even when they include efficiently translated uORFs up to 70 amino acids long, or structured uORFs, in the absence of reinitiation. These data highlight an apparent difference between the rules that govern the exposure of uORF-containing transcripts to NMD in mammalian and plant cells.
Dynamics of Rubisco regulation by sugar phosphate derivatives and their phosphatases
Authors: Orr Douglas J , Robijns Alice K J , Baker Christopher R , Niyogi Krishna K , Carmo-Silva Elizabete
Published: September 2022

Regulating the central CO2-fixing enzyme Rubisco is as complex as its ancient reaction mechanism and involves interaction with a series of cofactors and auxiliary proteins that activate catalytic sites and maintain activity. A key component among the regulatory mechanisms is the binding of sugar phosphate derivatives that inhibit activity. Removal of inhibitors via the action of Rubisco activase is required to restore catalytic competency. In addition, specific phosphatases dephosphorylate newly released inhibitors, rendering them incapable of binding to Rubisco catalytic sites. The best studied inhibitor is 2-carboxy-d-arabinitol 1-phosphate (CA1P), a naturally occurring nocturnal inhibitor that accumulates in most species during darkness and low light, progressively binding to Rubisco. As light increases, Rubisco activase removes CA1P from Rubisco, and the specific phosphatase CA1Pase dephosphorylates CA1P to CA, which cannot bind Rubisco. Misfire products of Rubisco’s complex reaction chemistry can also act as inhibitors. One example is xylulose-1,5-bisphosphate (XuBP), which is dephosphorylated by XuBPase. Here we revisit key findings related to sugar phosphate derivatives and their specific phosphatases, highlighting outstanding questions and how further consideration of these inhibitors and their role is important for better understanding the regulation of carbon assimilation.
The jet formation mechanism of gamma-ray narrow-line Seyfert 1 galaxies
Authors: Chen (陈永云) Yongyun , Gu (顾秋生) Qiusheng , Fan (樊军辉) Junhui , Yu (俞效龄) Xiaoling , Ding (丁楠) Nan , Guo (郭晓通) Xiaotong , Xiong (熊定荣) Dingrong
Published: September 2022

Under a coronal magnetic field, we estimate the maximal jet power of the Blandford–Znajek (BZ) mechanism, Blandford–Payne (BP) mechanism, and hybrid model. The jet power of the BZ and hybrid model mechanisms depends on the spin of the black hole, while the jet power of the BP mechanism does not depend on the spin of the black hole. At high black hole spin, the jet power of the hybrid model is greater than that of the BZ and BP mechanisms. We find that the jet power of almost all gamma-ray narrow-line Seyfert 1 galaxies (γNLS1s) can be explained by the hybrid model. However, one source with jet power ∼0.1–1 Eddington luminosity cannot be explained by the hybrid model. We suggest that a magnetic field dragged inward by the accretion disc with magnetization-driven outflows may accelerate the jets in this γNLS1.
Lack of influence of the environment in the earliest stages of massive galaxy formation
Authors: Annunziatella Marianna , Pérez-González Pablo G , García Argumánez Ángela , Barro Guillermo , Alcalde Pampliega Belén , Costantin Luca , Koekemoer Anton M , Mérida Rosa M
Published: September 2022

We investigate how the environment affects the assembly history of massive galaxies. For that purpose, we make use of Survey for High-z Absorption Red and Dead Sources (SHARDS) and HST spectrophotometric data, whose depth, spectral resolution, and wavelength coverage allow to perform a detailed analysis of the stellar emission as well as obtaining unprecedentedly accurate photometric redshifts. This expedites a sufficiently accurate estimate of the local environment and a robust derivation of the star formation histories of a complete sample of 332 massive galaxies (>1010M⊙) at redshift 1 ≤ z ≤ 1.5 in the GOODS-N field. We find that massive galaxies in this redshift range avoid the lowest density environments. Moreover, we observed that the oldest galaxies in our sample with mass-weighted formation redshift $\mathrm{\overline{z}_{M-w} \ge 2.5}$, avoid the highest density regions, preferring intermediate environments. Younger galaxies, including those with active star formation, tend to live in denser environments ($\Sigma = \mathrm{5.0_{1.1}^{24.8}\times 10^{10}\, M_{\odot }\, Mpc^{-2}}$). This behaviour could be expected if those massive galaxies starting their formation first would merge with neighbours and sweep their environment earlier. On the other hand, galaxies formed more recently ($\overline{z}_{M-w} \lt 2.5$) are accreted into large-scale structures at later times and we are observing them before sweeping their environment or, alternatively, they are less likely to affect their environment. However, given that both number and mass surface densities of neighbour galaxies is relatively low for the oldest galaxies, our results reveal a very weak correlation between environment and the first formation stages of the earliest massive galaxies.
X-ray spectral and timing analysis of the Compton Thick Seyfert 2 galaxy NGC 1068
Authors: Pal Indrani , Stalin C S , Parker M L , Agrawal Vivek K , Marchesi S
Published: September 2022

We present the timing and spectral analysis of the Compton Thick Seyfert 2 active galactic nuclei NGC 1068 observed using NuSTAR and XMM–Newton. In this work for the first time we calculated the coronal temperature ($\rm {kT_{e}}$) of the source and checked for its variation between the epochs if any. The data analysed in this work comprised of (a) eight epochs of observations with NuSTAR carried out during the period 2012 December to 2017 November, and, (b) six epochs of observations with XMM–fNewton carried out during 2000 July to 2015 February. From timing analysis of the NuSTAR observations, we found tfhe source not to show any variations in the soft band. However, on examination of the flux at energies beyond 20 keV, during 2014 August and 2017 August the source was brighter by about 20 and 30 per cent, respectively, compared to the mean flux of the three 2012 NuSTAR observations as in agreement with earlier results in literature. From an analysis of XMM–Newton data we found no variation in the hard band (2–4 keV) between epochs as well as within epochs. In the soft band (0.2–2 keV), while the source was found to be not variable within epochs, it was found to be brighter in epoch B relative to epoch A. By fitting physical models we determined $\rm {kT_{e}}$ to range between 8.46$^{+0.39}_{-0.66}$ and 9.13$^{+0.63}_{-0.98}$ keV. From our analysis, we conclude that we found no variation of $\rm {kT_{e}}$ in the source.