bluuebunny/crossref_metadata_2025 huggingface dataset:
Immunvermittelte Sinus- und Hirnvenenthrombosen: VITT und
prä-VITT als Modellerkrankung
Authors: Salih Farid , Schönborn Linda , Endres Matthias , Greinacher Andreas
Published: November 2022

In diesem Übersichtsartikel beschreiben wir die klinischen und
paraklinischen Charakteristika der Vakzin-induzierten immunthrombotischen
Thrombozytopenie (VITT) und fassen den gegenwärtigen Kenntnisstand zur
Pathogenese zusammen. Bei der VITT bilden sich 5–20 Tage nach einer
Impfung mit einem Adenovirus-vektorbasiertem SARS-CoV-2-Vakzin (AstraZeneca oder
Johnson & Johnson) lebensbedrohliche Thrombosen aus, vor allem in den
zerebralen Sinus und Hirnvenen. Laborchemisch zeigt sich eine typische
Thrombozytopenie mit erhöhten D-Dimeren. Der Pathogenese liegen
immunologische Prozesse zugrunde, die Ähnlichkeiten mit der
Heparin-induzierten Thrombozytopenie aufweisen: so geht die VITT mit
hochtitrigem Immunoglobulin G gegen das thrombozytäre Protein
Plättchenfaktor 4 (PF4) einher. Durch die Interaktion mit dem Impfstoff
wird PF4 so verändert, dass es von Antikörper-produzierenden
Zellen des Immunsystems erkannt wird. Die so produzierten
Anti-PF4-Antikörper führen über thrombozytäre
FcγIIa-Rezeptoren zu einer Plättchenaktivierung. Der Nachweis
plättchenaktivierender Anti-PF4-Antikörper bestätigt die
Diagnose einer VITT. Antikoagulanzien, die die Bildung von Thrombin oder
Thrombin selbst blockieren und hochdosiertes i. v.-Immunglobulin G, das
die Fcγ-Rezeptor-vermittelte Zellaktivierung inhibiert, stellen die
wirksame und kausale Behandlung der VITT dar. Bei Patienten mit katastrophalem
Verlauf kann ein Plasmaaustausch versucht werden. Bei einigen Patienten ist ein
prä-VITT Syndrom als Prodromalstadium zu beoachten, das sich
typischerweise mit Kopfschmerzen manifestieren kann und dessen frühe
Behandlung hilft, thrombotische Komplikationen zu vermeiden. Die spezifische
Dynamik der VITT-assozierten Immunreaktion entspricht einer transienten,
sekundären Immunantwort. Aktuelle Studien gehen der Frage nach, wie PF4
an unterschiedliche adenovirale Proteine bindet und beleuchten die Rolle von
anderen Impfstoff-Bestandteilen als potentielle Liganden für die
PF4-Bindung. Einige dieser Faktoren sind auch an der Etablierung eines
proinflammatorischen Milieus („danger signal“) beteiligt, das
unmittelbar nach der Impfung die 1. Phase der VITT-Pathogenese triggert. Sobald
in der 2. Phase der VITT-Pathogenese hohe Titer von Anti-PF4-Antikörper
gebildet sind, aktivieren diese neben Thrombozyten auch Granulozyten. In einem
als NETose (von „neutrophil extracellular traps“) bezeichneten
Prozess setzen aktivierte Granulozyten dabei DNA frei, mit der PF4 weitere
Komplexe bildet, an die Anti-PF4-Antikörper binden. Dies
verstärkt die Fcγ-Rezeptor-vermittelte Zellaktivierung weiter
mit der Folge einer ausgeprägten Thrombin-Bildung. Zum Ende des Artikels
geben wir einen Ausblick, welchen Einfluss die bisherigen Erkenntnisse zur VITT
auf weitere globale Impfkampagnen gegen SARS-CoV-2 haben und beleuchten, wie
Anti-PF4-Antikörper jenseits von VITT und HIT auch eine Rolle bei
seltenen Erkrankungen spielen, die mit rezidivierenden venösen und
arteriellen Thrombosen einhergehen.
Cement Beads at First Stage Improve Femoral Endosteal Recovery: A Comparative Study of Revision and Primary Taper Slip Femoral Components
Authors: Shelton James , Khaliq Mehnoor , Barrow Jonathan , McGran Sophie , Hamer Andrew
Published: November 2022

Debate continues about the merits of nonarticulating cement beads versus articulating cement spacers. This unit believes beads promote femoral endosteal bone regeneration producing an environment conducive to cementing at second stage. This article assesses the femoral cement mantle of matched primary and revision cemented taper slip stems (CTSSs). We performed a retrospective cohort study of all second stage CTSSs then selected a randomized group from primary joints from the arthroplasty database. The two revision hip fellows assessed the initial postop radiograph for femoral cement quality using the Barrack grading system. Results were analyzed using SPSS for interobserver reliability and quality of cementing. A total of 105 patients were identified as having received a CTSS at second stage and 105 primaries randomly selected. The average age was 81 years in the revision group and 79 years in the primary group. The revision group contained 54% female patients and the primary group contained 56%. In the primary group 73% on anteroposterior (AP) were grade A and 65% on lateral. In the revision group 77% on AP were grade A and 76% on the lateral. The interclass correlation coefficient showed good correlation between assessors. Only the lateral cementing demonstrated a significant difference between groups in favor of the revision group. This article suggests that the use of beads at first stage followed by a cemented femoral prosthesis at second stage will have equal to, or slightly better cementing than those receiving a primary hip replacement. We believe that cement can have additional benefits in second stage revisions such as further delivery of antibiotics into the effective joint space. As revision surgeons we aim to foster as many options as possible for the subsequent reconstruction. The major limitation of this study is the low number of articulating spacers used in this institution.
A Rare Biotinidase Deficiency in the Pediatrics Population: Genotype–Phenotype Analysis
Authors: Kannan Balachander , Navamani Hepzibah Kirubamani , Jayaseelan Vijayashree Priyadharsini , Arumugam Paramasivam
Published: November 2022

Biotinidase (BTD) deficiency is a rare autosomal recessive metabolic disorder caused by insufficient biotin metabolism, where it cannot recycle the vitamin biotin. When this deficiency is not treated with supplements, it can lead to severe neurological conditions. Approximately 1 in 60,000 newborns are affected by BTD deficiency. The BTD deficiency causes late-onset biotin-responsive multiple carboxylase deficiency, which leads to acidosis or lactic acidosis, hypoglycemia, and abnormal catabolism. BTD deficiency is of two types based on the amount of BTD Enzyme present in the serum. A wide range of pathogenic mutations in the BTD gene are reported worldwide. Mutations in the BTD gene lead to profound and partial BTD deficiency. Profound BTD deficiency results in a severe pathogenic condition. A high frequency of newborns are affected with the partial deficiency worldwide. They are mostly asymptomatic, but symptoms may appear during stressful conditions such as fasting or viral infections. Several pathogenic mutations are significantly associated with neurological, ophthalmological, and skin problems along with several other clinical features. This review discusses the BTD gene mutation in multiple populations detected with phenotypic features. The molecular-based biomarker screening is necessary for the disease during pregnancy, as it could be helpful for the early identification of BTD deficiency, providing a better treatment strategy. Moreover, implementing newborn screening for the BTD deficiency helps patients prevent several diseases.
Anatomy and Physiology of Headache
Authors: Harriott Andrea M. , Orlova Yulia
Published: November 2022

Headache disorders can produce recurrent, incapacitating pain. Migraine and cluster headache are notable for their ability to produce significant disability. The anatomy and physiology of headache disorders is fundamental to evolving treatment approaches and research priorities. Key concepts in headache mechanisms include activation and sensitization of trigeminovascular, brainstem, thalamic, and hypothalamic neurons; modulation of cortical brain regions; and activation of descending pain circuits. This review will examine the relevant anatomy of the trigeminal, brainstem, subcortical, and cortical brain regions and concepts related to the pathophysiology of migraine and cluster headache disorders.
Migraine and Posttraumatic Headache: Similarities and Differences in Brain Network Connectivity
Authors: Chong Catherine D. , Nikolova Jennifer , Dumkrieger Gina M.
Published: November 2022

Posttraumatic headache (PTH) is the most common symptom following mild traumatic brain injury (mTBI) (also known as concussion). Migraine and PTH have similar phenotypes, and a migraine-like phenotype is common in PTH. The similarities between both headache types are intriguing and challenge a better understanding of the pathophysiological commonalities involved in migraine and PTH due to mTBI. Here, we review the PTH resting-state functional connectivity literature and compare it to migraine to assess overlap and differences in brain network function between both headache types. Migraine and PTH due to mTBI have overlapping and disease-specific widespread alterations of static and dynamic functional networks involved in pain processing as well as dysfunctional network connections between frontal regions and areas of pain modulation and pain inhibition. Although the PTH functional network literature is still limited, there is some evidence that dysregulation of the top-down pain control system underlies both migraine and PTH. However, disease-specific differences in the functional circuitry are observed as well, which may reflect unique differences in brain architecture and pathophysiology underlying both headache disorders.
Update Pädiatrie (1): Die Internationale Klassifikation der Funktionsfähigkeit, Behinderung und Gesundheit (ICF) in der Pädiatrie
Authors: Hofer Julia , Nallinger Andrea
Published: November 2022

Dieser und die nachfolgenden zwei Artikel geben einen Einblick in die aktuelle Physiotherapie mit Kindern. Der erste Beitrag dieses Pädiatrie-Updates stellt Ihnen die ICF vor, wie sie die Weltgesundheitsorganisation auf Kinder und Jugendliche angepasst hat. Mit dem zweiten Beitrag (► Seite 20) können Sie Ihr Wissen über die Infantile Zerebralparese aktualisieren. Der dritte Artikel bietet Ausschnitte aus dem physiotherapeutischen Prozess bei Kindern mit Infantiler Zerebralparese (► Seite 22).
Back of the class: Capturing vortices from those ahead helps fish swim more efficiently in schools
Authors: Liebendorfer Adam
Published: November 2022

Understanding how fish rely on wakes for increased speed and efficiency could provide insights into marine social structures and underwater drones.
Commutators of random matrices from the unitary and orthogonal groups
Authors: Palheta Pedro H. S. , Barbosa Marcelo R. , Novaes Marcel
Published: November 2022

We investigate the statistical properties of C = uvu−1v−1, when u and v are independent random matrices, uniformly distributed with respect to the Haar measure of the groups U(N) and O(N). An exact formula is derived for the average value of power sum symmetric functions of C, and also for products of the matrix elements of C, similar to Weingarten functions. The density of eigenvalues of C is shown to become constant in the large-N limit, and the first N−1 correction is found.
Estimation of decay rates to large-solutions of 3D compressible magnetohydrodynamic system
Authors: Wang Shuai , Chen Fei , Zhao Yongye , Wang Chuanbao
Published: November 2022

The aim of this paper is to get an estimation of decay rates to first-order and second-order derivatives of space for large-solutions to 3D compressible magnetohydrodynamic system. While the condition (σ0 − 1, u0, Q0) ∈ L1 ∩ H2 is satisfied via a classical energy method and Fourier splitting method, first-order and second-order derivatives of space for large-solutions tending to 0 by L2-rate (1+t)−54 are shown. It is a necessary supplement to the result of Gao, Wei, and Yao [Appl. Math. Lett. 102, 106100 (2020)] in which they only obtained an estimation of decay rates to magnetic fields. Meanwhile, compared with the work of Gao, Wei, and Yao [Physica D 406, 132506 (2020)], we find that the appearance of magnetic fields does not have any bad effect on the estimation of decay rates to both the velocity field and density.
Investigating the effect of the mean path length on reluctance actuator output force characterization
Authors: Pumphrey Michael , Al Saaideh Mohammad , Kuchinkaa Kaitlyn , Alatawneh Natheer , Al Janaideh Mohammad
Published: November 2022

This paper investigates the effect of the flux’s mean path length (MPL) on the reluctance actuator’s analytical model. It determines the circumstances where the model neglecting the MPL is valid. The analysis is carried out for both C-Core and E-Core reluctance actuators; the analytical results are calculated by using MATrix LABoratory and then validated against a finite element model simulation by using COMputer SOLution Multiphysics. In addition, the experimental results of the magnetic force of C-Core and E-Core reluctance actuators are presented and compared with the analytical model. The comparison is obtained under different input currents and air gaps for two different ferromagnetic materials. It can be concluded that the analytical model is valid only for air gaps with a relatively high air gap displacement and for small air gaps, considering the MPL is necessary for accurate results. This means that whenever the reluctance actuator is proposed for high-precision motion system applications, it is essential that the analysis takes into account the effect of the MPL.
Toward the fabrication of a 5-μm-resolution Wolter microscope for the National Ignition Facility (invited)
Authors: Champey Patrick R. , Kolodziejczak Jeffery , Kozioziemski Bernard , Davis Jacqueline , Griffith Charles , Kester Tom , Kilaru Kiranmayee , Meekham Amy , Menapace Joe , Ramsey Brian , Roberts Oliver J. , Sanchez Javier , Singam Panini , Smith W. Scott , Speegle Chet , Stahl Mark , Suratwala Tayyab , Thomas Nick , Young Mark , Vogel Julia K.
Published: November 2022

Advancements in computer-controlled polishing, metrology, and replication have led to an x-ray mirror fabrication process that is capable of producing high-resolution Wolter microscopes. We present the fabrication and test of a nickel–cobalt replicated full-shell x-ray mirror that was electroformed from a finely figured and polished mandrel. This mandrel was designed for an 8-m source-to-detector-distance microscope, with 10× magnification, and was optimized to reduce shell distortions that occur within 20 mm of the shell ends. This, in combination with an improved replication tooling design and refined bath parameters informed by a detailed COMSOL Multiphysics® model, has led to reductions in replication errors in the mirrors. Mandrel surface fabrication was improved by implementing a computer-controlled polishing process that corrected the low-frequency mandrel figure error and achieved <2.0 nm RMS convergence error. X-ray tests performed on a pair of mirror shells replicated from the mandrel have demonstrated <10 μm full-width at half-maximum (FWHM) spatial resolution. Here, we discuss the development process, highlight results from metrology and x-ray testing, and define a path for achieving a program goal of 5 μm FWHM resolution.
Cupolets in a chaotic neuron model
Authors: Parker John E. , Short Kevin M.
Published: November 2022

This paper reports the first finding of cupolets in a chaotic Hindmarsh–Rose neural model. Cupolets (chaotic, unstable, periodic, orbit-lets) are unstable periodic orbits that have been stabilized through a particular control scheme by applying a binary control sequence. We demonstrate different neural dynamics (periodic or chaotic) of the Hindmarsh–Rose model through a bifurcation diagram where the external input current, I, is the bifurcation parameter. We select a region in the chaotic parameter space and provide the results of numerical simulations. In this chosen parameter space, a control scheme is applied when the trajectory intersects with either of the two control planes. The type of the control is determined by a bit in a binary control sequence. The control is either a small microcontrol (0) or a large macrocontrol (1) that adjusts the future dynamics of the trajectory by a perturbation determined by the coding function rN(x). We report the discovery of many cupolets with corresponding control sequences and comment on the differences with previously reported cupolets in the double scroll system. We provide some examples of the generated cupolets and conclude by discussing potential implications for biological neurons.
A theoretical examination of localized nanoscale induction by single domain magnetic particles
Authors: Christiansen Michael G. , Mirkhani Nima , Hornslien William , Schuerle Simone
Published: November 2022

Single domain magnetic nanoparticles are increasingly investigated as actuators of biological and chemical processes that respond to externally applied magnetic fields. Although their localized effects have often been attributed to nanoscale heating, recent experimental evidence suggests the need to consider alternative hypotheses. Here, using the stochastic Landau–Lifshitz–Gilbert equation and finite element modeling, we investigate and critically examine an alternative hypothesis that localized effects may instead involve the induced electric fields arising from the dynamical behavior of individual single domain magnetic particles. We model the magnetization dynamics and resulting induced electric fields for two relevant and distinct cases of magnetic nanoparticles in alternating magnetic fields: (1) magnetogenetic stimulation of channel proteins associated with ferritin and (2) catalytic enhancement of electrochemical hydrolysis. For the first case, while the local electric fields that ferritin generates are shown to be insufficient to perturb the transmembrane potential, fields on the surface of its mineral core on the order of 102–103 V/m may play a more plausible role in mass transport of iron ions that indirectly lead to stimulation. For the second case, our model indicates that the highest interfacial electric field strengths, on the order of 102 V/m, are expected during reversal events. Thus, nanoparticles well suited for hysteresis heating can also act as intermittent sources of localized induced electric fields in response to an alternating applied field. Finally, we compare the magnitude and timescale of these electric fields to technologically relevant phenomena, showing that they are generally weaker and faster.
Two-dimensional Lifshitz-like AdS black holes in F(R) gravity
Authors: Eslam Panah B.
Published: November 2022

Two-dimensional (2D) Lifshitz-like black holes in special F(R) gravity cases are extracted. We indicate an essential singularity at r = 0, covered by an event horizon. Then, conserved and thermodynamic quantities, such as temperature, mass, entropy, and the heat capacity of 2D Lifshitz-like black holes in F(R) gravity, are evaluated. Our analysis shows that 2D Lifshitz-like black hole solutions can be physical solutions, provided that the cosmological constant is negative (Λ < 0). Indeed, there is a phase transition between stable and unstable cases by increasing the radius of AdS black holes. In other words, the 2D Lifshitz-like AdS black holes with large radii are physical and enjoy thermal stability. The obtained 2D Lifshitz-like AdS-black holes in F(R) gravity turn into the well-known 2D Schwarzschild AdS-black holes when the Lifshitz-like parameter is zero (s = 0). Moreover, correspondence between these black hole solutions and the 2D rotating black hole solutions is found by adjusting the Lifshitz-like parameter.
Harmonic and anharmonic oscillators on the Heisenberg group
Authors: Rottensteiner David , Ruzhansky Michael
Published: November 2022

In this article, we present a notion of the harmonic oscillator on the Heisenberg group Hn, which, under a few reasonable assumptions, forms the natural analog of a harmonic oscillator on Rn: a negative sum of squares of operators on Hn, which is essentially self-adjoint on L2(Hn) with purely discrete spectrum and whose eigenvectors are Schwartz functions forming an orthonormal basis of L2(Hn). The differential operator in question is determined by the Dynin–Folland group—a stratified nilpotent Lie group—and its generic unitary irreducible representations, which naturally act on L2(Hn). As in the Euclidean case, our notion of harmonic oscillator on Hn extends to a whole class of so-called anharmonic oscillators, which involve left-invariant derivatives and polynomial potentials of order greater or equal 2. These operators, which enjoy similar properties as the harmonic oscillator, are in one-to-one correspondence with positive Rockland operators on the Dynin–Folland group. The latter part of this article is concerned with spectral multipliers. We obtain useful Lp-Lq-estimates for a large class of spectral multipliers of the sub-Laplacian LHn,2 and, in fact, of generic Rockland operators on graded groups. As a by-product, we obtain explicit hypoelliptic heat semigroup estimates and recover the continuous Sobolev embeddings on graded groups, provided 1 < p ≤ 2 ≤ q < ∞.
Trap-assisted tunneling as possible carrier escape mechanism in InGaN/GaN light-emitting diodes
Authors: Lu Boyang , Hao Zhibiao , Luo Yi , Sun Changzheng , Han Yanjun , Xiong Bing , Wang Jian , Li Hongtao , Wang Lai
Published: November 2022

Carrier escape has been widely observed in light-emitting diodes (LEDs) and it is crucial to the performance of quantum-well photovoltaic and photodetector devices. However, the mechanisms proposed thus far, including thermionic emission and direct tunneling, fail to explain the experimental results. In this work, a simplified trap-assisted tunneling model that considers the energy distribution on trap states is established through which experiment results can be explained reasonably. The nonuniform distribution of diffused p-type dopants is proposed as the reason for the abnormal voltage-dependent and excitation-energy-dependent photocurrent experimental results through energy band diagram simulation.
Global well-posedness to the Cauchy problem of 2D nonhomogeneous Bénard system with large initial data and vacuum
Authors: Li Huanyuan
Published: November 2022

This paper establishes the global well-posedness of strong solutions to the nonhomogeneous Bénard system with positive density at infinity in the whole space R2. We obtain the global existence and uniqueness of strong solutions for general large initial data. Our method relies on the dedicate energy estimates and a logarithmic interpolation inequality.
Electronic and magnetic properties of pure and Cu doped non-polar ZnO (101¯0) surfaces
Authors: Irandegani Esmat , Maezono Ryo , Abbasnejad Mohaddeseh
Published: November 2022

In the present work, the electronic and magnetic properties of pure and Cu doped ZnO thin films in the non-polar [101¯0] direction have been investigated in the framework of density functional theory. The bandgap of pure surface was slightly lower than that of the bulk. By doping Cu impurity in the surface, the bandgap decreased relative to that of the pure surface, which is in the visible light region. Furthermore, the spin up and down behaved differently, presenting half-metallic behavior with a net magnetization as large as 1 μB/cell. These results imply that Cu doped ZnO surface can be applicable in spintronic and optical applications. By including O vacancy in Cu doped surface configurations, the bandgap was decreased leading to the metallic behavior. Furthermore, different magnetization was obtained for each configuration. It states that the presence of O vacancy in Cu doped ZnO surface may affect the induced magnetization in ZnO thin films.
Monte-Carlo simulations based hub height optimization using FLORIS for two interacting onshore wind farms
Authors: Kütükçü Gökay , Uzol Oğuz
Published: November 2022

This study focuses on finding the optimum hub height (i.e., tower height) distributions for two interacting on-shore wind farms that are located on relatively complex terrain. Different optimization scenarios are studied, which take into account both the wind farm power output and the relevant cost variations due to changing hub heights. Simulations are performed using the Flow Redirection and Induction in Steady State (FLORIS) framework, which is modified to represent significant variations in hub height levels due to elevation differences, hence partial wake interactions that are occurring as a consequence, are more realistically represented. Optimization is based on a systematic procedure that includes introducing definitions of overall evaluation criterion parameters for objective setting and generation of design of experiments tables and related data via FLORIS simulations to properly cover the design space. A Pareto analysis of generated data to find the most influential parameters is then performed, and response surfaces are generated to represent these variations, which are, in turn, used for Monte Carlo based simulations to determine the optimized hub height distributions. Overall, the optimized results show a reasonable increase can be achieved in wind farm power output levels, while total tower height levels (hence related cost levels) are either not changing or in some cases even getting reduced for the wind farms in consideration.
Radiative thermal conductance between nanostructures
Authors: Pérez-Madrid A. , Santamaría-Holek I.
Published: November 2022

Using a properly rescaled Planck's law, the emission spectrum from nanostructures having one or two dimensions in the nanometric length scale is studied. We account for size and shape effects on the radiative heat exchange between nanostructures. This rescaling involves a size-dependent hypothetical temperature obtained from Wien's displacement law. We derive analytical expressions for the absorption cross section and heat conductance in terms of both the length characterizing the shape-anisotropy and the control temperature. Comparison with the experimental data shows a remarkable agreement.
Computational study on the uptake of soft nanoparticles and nanoparticle cluster by cells
Authors: Xu Wu , Liu Xiaohu
Published: November 2022

Nanoparticles (NPs) and exosomes used to transport therapeutic drug molecules to cells have attracted considerable attention in biopharmaceuticals. However, soft NPs entering cells with different angles are hard to be simulated by traditional theoretical endocytic models, let alone clustering of NPs with varied shapes. Here, the endocytic model based on the co-rotational grid method is implemented. The endocytosis of a single soft NP and a nanoparticle cluster (NPC) are investigated. Both the actin force and the dynamic assembly of the clathrin coat have been considered. The results show that NP size is the main factor affecting the internalization efficiency, followed by the aspect ratio, and finally the entry angle. The increase in NP size, aspect ratio, and entry angle will lead to a decrease in internalization efficiency. However, the final configuration of the endocytic vesicle and the internalization efficiency are both independent of the entry angle for NPs with an equivalent radius greater than 15 nm. Besides, a large entry angle can assist a large soft NP in successfully entering cells. The increase in NP stiffness also reduces the internalization efficiency considering the actin force required during endocytosis. The transformation of the NP from the inclined configuration to the vertical configuration is mainly due to NP deformation. Compared with a single NP, NPC has a lower internalization efficiency. The results provide new mechanistic insights into the endocytosis of soft NPs and NPCs.
An attack–defense game model in infrastructure networks under link hiding
Authors: Qi Gaoxin , Li Jichao , Xu Xueming , Chen Gang , Yang Kewei
Published: November 2022

Our increasing dependence on infrastructure networks leads to growing concerns over the protection of these networks. Many methods have been proposed to select protective strategies by combining complex network theory and game theory. However, the misleading effect of hidden links is not considered in previous methods. This work creates an information gap between attackers and defenders by partly hiding network links to mislead the attacker in the game. We first introduce the rule of link hiding that depends on the nodes’ property, where the number of hidden links has a maximum value. Additionally, based on the Stackelberg game model, we establish an attack–defense game model with link hiding strategies considering node property and cost constraints. Finally, we conduct experiments in a scale-free network and an existing power grid. The experimental results show that the defender tends to combine first-mover advantage and link hiding to get a better payoff under more different costs of the nodes. Hiding half of the links in the existing power grid can effectively reduce network damage by about 22.8% on average, with the two sides investing the same resources. The effect of link hiding could be more obvious when the attacker owns more resources than the defender. When an attacker employs the high-degree attacking strategy, the proposed link hiding method can help the defender reduce the damage to the network by 12.2% compared to the link reconnecting method.
Permutation group entropy: A new route to complexity for real-valued processes
Authors: Amigó José M. , Dale Roberto , Tempesta Piergiulio
Published: November 2022

This is a review of group entropy and its application to permutation complexity. Specifically, we revisit a new approach to the notion of complexity in the time series analysis based on both permutation entropy and group entropy. As a result, the permutation entropy rate can be extended from deterministic dynamics to random processes. More generally, our approach provides a unified framework to discuss chaotic and random behaviors.
TM2B3 monolayers: Intrinsic anti-ferromagnetism and Dirac nodal line semimetal
Authors: Sun Yi , Wang Licheng , Li Xiaoyan , Yao Xiaojing , Xu Xiaokang , Guo Tianxia , He Ailei , Wang Bing , Liu Yongjun , Zhang Xiuyun
Published: November 2022

Searching for two-dimensional materials combining both magnetic order and topological order is of great significance for quantum devices and spintronic devices. Here, a class of two-dimensional transition metal borides, TM2B3 (TM = Ti–Ni), with high stability and stable antiferromagnetic (AFM) orders was predicted by using the first-principles method. The result shows that they possess large magnetic anisotropy energy and high critical temperature. Interestingly, Mn2B3 monolayer is confirmed to be AFM Dirac node line semimetal with several Dirac points near the Fermi level. Detailed analysis of the irreducible representations shows that the nodal lines are protected by the horizontal mirror symmetry Mz. Our findings provide an excellent platform for exploring topological and magnetic materials ready for the next generation of spintronic devices.
Effects of the normal load on the excited phonons in atomic friction
Authors: Wei Zhiyong , Xiang Li , Kan Yajing , Zhang Yan , Chen Yunfei
Published: November 2022

Although the quantitative relationship between the normal load and the induced friction force has been established from the phenomenological laws of friction, it does not answer the question of how mechanical energy is dissipated into heat by exciting phonons. In this study, the effects of normal load on the friction force of a relatively sliding graphene film are investigated by molecular dynamics simulations. The results show that the excited phonon modes couple with the resonant frequency of the entire frictional system, and the enhancement of the normal load is equivalent to the increase of the resonant frequency of the frictional system. It is also found that the relative intensity of the resonant peaks in the vibrational density of states is a key factor affecting the friction force, which can explain the variation of friction force with the normal load. Moreover, under a certain normal load, the friction force can reach its maximum value when the washboard frequency equals the resonant frequency of the frictional system. Our work establishes the relationship between the normal load and the frictional force from the phonon level, which provides a method for regulating atomic friction and energy dissipation by considering both washboard frequency and contact resonant frequency.
Thermoelectric figure-of-merit from Peltier cooling
Authors: Bhattacharya S. , Behlow H. , Rancu I. , Rao A. M. , Goldsmid H. J.
Published: November 2022

We use Peltier cooling to experimentally determine the thermoelectric figure-of-merit of a material, where the maximum temperature depression, ΔTmax, is simply related to Z of a thermocouple. However, for thermocouples comprising good thermoelectric materials with ZT≥1, ΔTmax can be large (≥100 K), making it difficult to assign the measurement to a particular temperature. This is less of a problem if the thermocouple consists of a semiconductor and a metal since ZT and ΔTmax are then much smaller. We developed a procedure for measuring the dimensionless figure-of-merit of a semiconductor using semiconductor-metal thermocouples in which the form factor (i.e., the ratio of areas to lengths of the two branches) is optimized. We also show valuable aspects in the ΔTmax measurement when the material dimensions are varied. Our experiments on couples consisting of a bismuth telluride alloy and constantan, and the corresponding theoretical analysis, show that the radiation losses are significant at ordinary temperatures. A good estimate of thermal conductivity and zT of the sample can be obtained when radiation losses are minimized.
Learning unseen coexisting attractors
Authors: Gauthier Daniel J. , Fischer Ingo , Röhm André
Published: November 2022

Reservoir computing is a machine learning approach that can generate a surrogate model of a dynamical system. It can learn the underlying dynamical system using fewer trainable parameters and, hence, smaller training data sets than competing approaches. Recently, a simpler formulation, known as next-generation reservoir computing, removed many algorithm metaparameters and identified a well-performing traditional reservoir computer, thus simplifying training even further. Here, we study a particularly challenging problem of learning a dynamical system that has both disparate time scales and multiple co-existing dynamical states (attractors). We compare the next-generation and traditional reservoir computer using metrics quantifying the geometry of the ground-truth and forecasted attractors. For the studied four-dimensional system, the next-generation reservoir computing approach uses ∼1.7× less training data, requires 103× shorter “warmup” time, has fewer metaparameters, and has an ∼100× higher accuracy in predicting the co-existing attractor characteristics in comparison to a traditional reservoir computer. Furthermore, we demonstrate that it predicts the basin of attraction with high accuracy. This work lends further support to the superior learning ability of this new machine learning algorithm for dynamical systems.
Some geometric inequalities on Riemannian manifolds associated with the generalized modified Ricci curvature
Authors: Huang Guangyue , Zhu Mingfang
Published: November 2022

In this paper, by establishing a Reilly-type formula with respect to the ϕ-Laplacian associated with the generalized modified Ricci curvature, we first obtain sharp lower bound estimates for the first eigenvalue of the ϕ-Laplacian. On the other hand, some new Brascamp–Lieb-type and Colesanti-type inequalities under some suitable boundary conditions are achieved. As applications, we also obtain some relationships between the weighted mean curvature of a boundary submanifold and the mean curvature of submanifold x : ∂M → RN(K) into space form RN(K).
PbS QDs/Al2O3/In0.53Ga0.47As infrared photodetector with fast response and high sensitivity
Authors: Chen Hu , Chen Jun
Published: November 2022

Due to the size effect, multi-exciton effect, confinement effect, and tunable bandgap, quantum dots (QDs) have gradually been used in near-infrared photodetectors. In this paper, PbS QDs were integrated with In0.53Ga0.47As materials, and a PbS QDs/In0.53Ga0.47As hybrid photodetector with Al2O3 was investigated. Passivation of PbS QDs by ligand replacement and insertion of Al2O3 reduced the dark current density from 9.24 × 10−6 to 4.67 × 10−6 A·cm−2, which enabled the detector to obtain a high responsivity of 0.97 A·W−1 under −1 V bias, and the detectivity reached 2.21 × 1010 Jones. In addition, we found that the PbS QDs/In0.53Ga0.47As near-infrared photodetector with Al2O3 obtained a fast rise and fall time, which could respond to high-frequency signals. The findings will have application in the PbS QDs/In0.53Ga0.47As hybrid near-infrared photodetectors.
Giant oscillations of diffusion in ac-driven periodic systems
Authors: Marchenko I. G. , Zhiglo A. , Aksenova V. , Tkachenko V. , Marchenko I. I. , Łuczka J. , Spiechowicz J.
Published: November 2022

We revisit the problem of diffusion in a driven system consisting of an inertial Brownian particle moving in a symmetric periodic potential and subjected to a symmetric time-periodic force. We reveal parameter domains in which diffusion is normal in the long time limit and exhibits intriguing giant damped quasiperiodic oscillations as a function of the external driving amplitude. As the mechanism behind this effect, we identify the corresponding oscillations of difference in the number of locked and running trajectories that carry the leading contribution to the diffusion coefficient. Our findings can be verified experimentally in a multitude of physical systems, including colloidal particles, Josephson junction, or cold atoms dwelling in optical lattices, to name only a few.
Spreading and retraction of the concentric impact of a drop with a sessile drop of the same liquid: Effect of surface wettability
Authors: Abouelsoud Mostafa , Thale Vinod A. , Shmroukh Ahmed N. , Bai Bofeng
Published: November 2022

The concentric impact on a sessile drop is relevant in many applications, including spray coating and icing phenomena. Herein, the spreading and retraction phases yielded during the impact of a coaxial drop with a sessile drop on a solid substrate were empirically and analytically examined. We analyzed the effects of surface wettability on the impact outcomes utilizing five distinctive surfaces (i.e., smooth glass, aluminum, copper, Teflon, and coated glass). The results showed that the merged drop takes longer to attain its maximum spreading diameter at a relatively higher contact angle of the sessile drop with the solid surface. Furthermore, based on energy balance, a model for predicting the maximum spreading diameter of the drop with varying surface wettability was presented. This model considers the assumption of viscous energy loss during the merging of falling and sessile drops and at the maximum spreading diameter. Additionally, the maximum retraction height during the impact on the coated glass surface was investigated. Our model results matched well with the experimental data.
Invariant tori in dissipative hyperchaos
Authors: Parker Jeremy P. , Schneider Tobias M.
Published: November 2022

One approach to understand the chaotic dynamics of nonlinear dissipative systems is the study of non-chaotic yet dynamically unstable invariant solutions embedded in the system’s chaotic attractor. The significance of zero-dimensional unstable fixed points and one-dimensional unstable periodic orbits capturing time-periodic dynamics is widely accepted for high-dimensional chaotic systems, including fluid turbulence, while higher-dimensional invariant tori representing quasiperiodic dynamics have rarely been considered. We demonstrate that unstable 2-tori are generically embedded in the hyperchaotic attractor of a dissipative system of ordinary differential equations; tori can be numerically identified via bifurcations of unstable periodic orbits and their parameteric continuation and characterization of stability properties are feasible. As higher-dimensional tori are expected to be structurally unstable, 2-tori together with periodic orbits and equilibria form a complete set of relevant invariant solutions on which to base a dynamical description of chaos.
Airfoil trailing-edge noise and drag reduction at a moderate Reynolds number using wavy geometries
Authors: Smith T. A. , Klettner C. A.
Published: November 2022

This study utilizes a hybrid aeroacoustic model to investigate how airfoils with spanwise wavy geometries can be used to reduce trailing-edge noise alongside improving the aerodynamic performance. A smooth airfoil is compared to four variants, which have spanwise surface waves of different wavelengths, at a Reynolds number of Re = 64 000 and an angle-of-attack of 1°. The first three variants have a geometry modified by a single wavelength, whereas the fourth has a surface composed of two wavelengths, which creates a more irregular surface variation. The results show that modest noise reductions of around 4 dB are achieved for the first three variants, but a much larger reduction of 17.7 dB is achieved for the fourth variant. The mechanisms behind the noise reduction are explored, and it is shown that the geometry reduces the spanwise correlation of the pressure fluctuations and also modifies the boundary layer dynamics, which contributes to the large reduction. It is further shown that a wavy geometry can reduce the drag force by reducing the shear stress over parts of the airfoil surface and by limiting the flow separation on the suction side. The fourth variant is also assessed across a wider range of angles (0°≤α≤4°) and is shown to produce less noise than the smooth wing across the entire range as well as a drag reduction for α≥1°.
Shear-imposed falling thin Newtonian film over a porous slippery surface
Authors: Hossain Md. Mouzakkir , Behera Harekrushna
Published: November 2022

The stability of a Newtonian thin film flow over a porous slippery wall approximated by Darcy's law is investigated. The modified Orr–Sommerfeld system is derived for the frequency-dependent linear stability analysis and energy-budget analysis. Moreover, in the longwave regime, both linear and weakly nonlinear stability analyses are conducted for small aspect ratios. In addition, the multiple scale approach is performed directly in the nonlinear deformation equation of the free surface to predict the extraordinary behavior of the amplitude and speed of the nonlinear disturbance in the subcritical and supercritical regimes. The study finds that the larger slip-velocity and externally imposed shear on the thin film increase the total kinetic energy of the infinitesimal perturbations. In a longwave regime, the critical conditions of the primary instability are described as a function of imposed shear stress that destabilizes the film flow for low critical Reynolds number. Furthermore, in the supercritical stable zone, both the nonlinear wave amplitude and phase speed increase with an increase in induced shear in the flow direction and velocity slip, and a reverse trend is observed in applying the imposed shear in the opposite flow direction. On the other hand, the nonlinear wave amplitude in the subcritical unstable zone increases and decreases, corresponding to the larger values of imposed shear and slip parameters, respectively.
Correspondence between the number of no-slip critical points and nature of rear stagnation point of a symmetric object
Authors: Mishra Shravan Kumar , Yadav Pavan Kumar , Sarkar Himalaya , Sen Subhankar
Published: November 2022

For flow around an isolated object, the points of zero vorticity/shear stress located at fluid–solid interface, i.e., the separation, reattachment points inclusive of forward and rear stagnation points are refered to as no-slip critical points. The total number, n (≥2), of such points is an even number. For flow past a diamond-section object, it is shown here that a change of the value of n by 2 alters the nature of its rear stagnation point. The rear stagnation point acts as a separation point for n = 2, 6, 10, etc. and as an attachment point for n = 4, 8, 12, etc. A pair of hypothetical mean wakes is proposed and their viability discussed with reference to results available in literature. Concerning flow past two in-line diamond cylinders, the formation of an “anti-wake” at the leading edge of the downstream cylinder renders its forward stagnation point to act as a separation point, which, otherwise for an isolated object, invariably serves as an attachment point. The forebody and afterbody of a symmetric object act as independent entities in influencing the nature of no-slip stagnation points.
Flow characteristics in non-conventional combustion chamber configurations
Authors: Amer Moustafa M. , Shouman Mahmoud A. , Megalaa Khairy F. , Salem Mohamed S.
Published: November 2022

Flow characteristics in combustion chambers of several non-circular cross-sectional configurations were numerically investigated. Different cross-sectional configurations, including annular and multi-sector annulus configurations with different fillets, were proposed, examined, and compared to the conventional circular arrangement. A numerical model was established and validated against other findings. The model was then used to study the effects of different design parameters, including convex and fillet radii, as well as some operational parameters, such as the angular velocity on the total pressure drop and the secondary flow characteristics like the swirl number, secondary vortex intensity, and helicity. The results revealed the optimum number of annulus sectors to be six, at which the highest hydraulic diameter was achieved for the same cross-sectional area. Optimum values of the inner and outer corner fillets were also obtained. Several valve arrangements were also investigated to achieve the highest possible valve area ratio for the proposed configurations. One of the proposed configurations, which incorporates six annular chambers with filleted corners with a hydraulic diameter ratio of 0.991 compared to the conventional circular design, denoted AFC4, achieved a more compact design while maintaining very comparable flow characteristics to those of the circular design. Although it needs more thorough investigations, it could present a viable alternative design option for the combustion chambers.
Stimulated emission in 24–31
μ
m range and «Reststrahlen» waveguide in HgCdTe structures grown on GaAs
Authors: Rumyantsev V. V. , Dubinov A. A. , Utochkin V. V. , Fadeev M. A. , Aleshkin V. Ya. , Razova A. A. , Mikhailov N. N. , Dvoretsky S. A. , Gavrilenko V. I. , Morozov S. V.
Published: November 2022

Long-wavelength stimulated emission (SE) is studied in optically pumped HgCdTe quantum well heterostructures with dielectric waveguides. Continuous temperature tuning of the wavelength from 27 to 18 μm is achieved in structures with optimized waveguides. Above 27 μm, SE clamps at 31 μm wavelength, where mode leaking is reduced due to the Reststrahlen effect in the GaAs substrate. The operating temperature is mainly limited by the activation of Auger recombination in quasi-equilibrium conditions, while at low temperatures, we expect that lowering initial carrier heating would enhance the gain considerably. We conclude that exploiting the Reststrahlen effect should allow one to achieve continuous wavelength tuning around 30 μm and operating wavelengths up to 40 μm with technologically attainable epistructure thickness.