Functional Switch Research Articles

An Attention Mechanism‐Based Adaptive Feedback Computing Component by Neuromorphic Ion Gated MoS2 Transistors

AbstractNeuromorphic computing is expected to bridge cognitive behaviors with computing systems in an efficient, expandable, and biologically inspired way. A pivotal cognitive behavior is the attention mechanism, which is highly important in filtering and regulating spatio‐temporal information. Emerging neuromorphic devices hold prospect in utilizing their internal physical mechanisms for dynamic computing resources. Here, a basic top–down attention computing component consisting of a synaptic transistor and a neuron is proposed, where efficient information processing is realized by combining the inherent device dynamics and the feedback loop. A theoretical model is established in simulation to demonstrate the capabilities of such a computing system in information filtering and control. Notably, new dynamic circuit behaviors, such as conductance oscillation and activate function switching, are discovered from appropriate time parameters. The attention computing component contains rich dynamic behaviors, providing a power and area‐saving method to construct high‐complexity neuromorphic systems for spatio‐temporal signal preprocessing and control.

ПЕРСПЕКТИВНАЯ АРХИТЕКТУРА ЦИФРОВОЙ ФОТОННОЙ ВЫЧИСЛИТЕЛЬНОЙ МАШИНЫ

Modern computationally intensive tasks of mathematical physics require continuous increasingof the performance of computer equipment used for their highly efficient solution. However,at present, the development of their electronic components is slowing down due to limitationsof technological production and operational processes. One of the ways to overcome the computerproductivity growth crisis is the development of digital photonic computers (DPC). In the paperwe suggest a promising DPC architecture, which consists of a functional subsystem, data streamsynchronization and switching subsystems, and photonic-electronic interfaces of data exchangewith external devices. We describe the principles of each subsystem. The functional subsystem is aset of DPC devices that provide 64-bit floating point arithmetic logic operations (according to theIEEE754 standard), implemented as linear pipelines with processing of least significant bits forward.The synchronization subsystem provides a single rate of data flow among various functionaldevices of the DPC, combined into a computing structure. According to the topology of the computingstructure, the switching subsystem controls the data streams at the stage of DPC programmingor during processing according to conditional transitions. For data exchange between theDPC and external devices, we suggest the technology of serialization of low-frequency parallelchannels and deserialization of high-frequency serial channels. We give a theoretical evaluation of the performance of the computing structures implemented on the DPC, which is similar to thestructures of mathematical physics problems concerning processing of special matrices. We showthat DPCs, due to their clock frequency, can provide the performance that exceeds the performanceof microelectronic devices by two and more orders of magnitude.

Stabilization of Asymmetric Underactuated Ships With Full-State Constraints: From Underactuated to Nonholonomic Configuration

Dear Editor, This letter addresses the stabilization control of an asymmetric underactuated surface ship with full-state constraints. To simplify the design of controller, the original ship model is transformed into a nonlinear cascade system with a minimum phase. Then, the stabilization of the cascade system is further processed into an equivalent stabilization of a reduced-order nonholonomic-like system. A discontinuous stabilization control method is proposed through a combination of state-scaling and state-dependent function transformations, nonlin-ear filters, and switching technologies. Stability analysis demon-strates that under the newly designed stabilization controller, the closed-loop system states are bounded and the desired state constraints are not violated.

Switchable terahertz absorber from single broadband to triple-narrowband

We proposed a switchable multifunctional terahertz (THz) absorber based on graphene and vanadium dioxide (VO 2 ), and investigated the absorption properties and the tuning of the absorber by using Computer Simulation Technology (CST) microwave studio. It was found that, when VO 2 is in dielectric phase, the structure shows a single broadband absorption from 0.8 to 2.4 THz range. The amplitude of the absorption can be tuned from 95 % to 20 % by changing the Fermi energy level of the graphene. And the absorption is found to be insensitive to the polarization angle and the incident angle. When VO 2 is in metallic phase, the absorber shows triple narrowband absorption. Utilizing impedance matching theory and transmission line theory, the physical mechanism of the absorber is investigated. • The designed structure is simple and easy to make in practice. • The proposed absorber has high efficient absorptivity. • The absorber enables functional switching between broadband and triple narrowband. • The absorber can achieve dynamic tuning of the single broadband absorptance.

Shifts in soil prokaryotic and microeukaryotic communities following a translocation of wet meadows to derelict land

AbstractHuman exploitation of natural resources dictates the need for the sustainable use of lands already in use. To combine the conservation of meadows with land recycling, 13,000 m2 of turf were translocated from a built‐up area to an abandoned quarry. Three Molinion meadows were monitored for three seasons—before the translocation and for two years afterwards. The composition of the main groups of microorganisms—bacteria, archaea, fungi, microfauna, and unicellular algae—was examined to check the stability of soil ecosystem. After observing changes in the ratio of ammonia to nitrate in the translocated turf, the bacterial and archaeal ammonia monooxygenase gene (amoA) copy numbers were quantified. Following the translocation, the α‐diversity of prokaryotes and eukaryotes remained usually similar. The structure of the microbial communities has changed: relative abundance of Acidobacteria (Acidobacteriota) and Mortierellomycota increased, along with fungal saprotrophs, while several other phyla decreased. The number of bacterial amoA gene copies has risen 7‐fold in two years. The slight acidification of the soil had an influence; however, the presumed turf aeration and moisture drop initially impacted the soil communities. In conclusion, turf block translocation preserves diversity. However, cutting turf for transportation followed by dryer conditions at the receptor location lead to a functional switch in microbial communities. Increased activities of ammonia oxidisers and saprotrophs proceeded to nitrification and humus degradation, which may indicate degradation of soil. When translocating wet meadows, it is crucial to ensure the hydrological regime at receptor sites to support long‐term success.

Thermally switchable, bifunctional, scalable, mid-infrared metasurfaces with VO2 grids capable of versatile polarization manipulation and asymmetric transmission

We conceptualized three-array scalable bifunctional metasurfaces comprising only three thin strip grids and numerically determined their characteristics in the mid-infrared spectral regime for switchable operation scenarios involving polarization manipulation and related diodelike asymmetric transmission (AT) as one of two functionalities. A few or all of the grids were taken to be made of VO2, a bifunctionality-enabling phase-change material; there are no layers and/or meta-atoms comprising simultaneously both metal and VO2. For each proposed metasurface, two effective structures and, therefore, two different functionalities exist, corresponding to the metallic and insulating phases of VO2. The achieved scenarios of functionality switching significantly depend on the way in which VO2 is incorporated into the metasurface. Switchable bands of polarization manipulation are up to 40 THz wide. The AT band can be modulated when Fabry–Perot (anti-) resonances come into play. Besides, transmission regimes with the cross-polarized component insensitive to VO2 phase change are possible, as well as the ones with all co- and cross-polarized components having the same magnitude for both linear polarizations of the incident wave.

Design of a new foot structure based on the mast-type octahedral tensegrity structure

• A foot structure was developed basing on mast-type octahedral tensegrity structure. • To obtain the ability of rigid-flexible switching by adding ratchet structure. • Better self-adaptability, self-stability, self-recovery and stable support capacity. • The foot structure can satisfy the human ankle joint reachable workspace . • The foot structure can enhance adaptability in walking. Foot performance plays an important role in the walking-style robot walking in complex ground. This paper proposes a new foot structure based on the mast-type octahedral tensegrity structure with the flexibility, self-stability and self-adaptability. First, the mast-type octahedral tensegrity structure is evolved, and the feasibility of the motion is verified by dynamic analysis, and the degrees of freedom of the structure are limited by adding cross-axis. Next, by adding a locking structure based on a ratchet structure, and it avoided the structural instability caused by excessive deformation of the tensegrity foot structure. Finally, the design of the new foot structure was completed and a physical prototype was fabricated to verify the function of the new foot structure through relevant experiments. The high symmetry of the mast-type octahedral tensegrity structure simplifies the stiffness matching of the elastic members of the tension foot mechanism. The locking structure based on the ratchet structure is used to realize the switching of the flexible adaptation function and the rigid support function of the tensegrity foot structure, thus avoiding the structural instability caused by excessive deformation of the tensegrity foot structure.

Resistive switching of two-dimensional NiAl-layered double hydroxides and memory logical functions

Two-dimensional NiAl layered double hydroxides (LDHs) were synthesized by urea hydrolysis method. Considering its unique layered structure and high-speed carrier transfer channel, NiAl-LDHs were applied to the active layer of memristor through spin coating process. It is found that the Al/NiAl-LDHs/Al memristor exhibits unipolar resistance switching characteristics, which resistive switching mechanism is attributed to formation and fusing of conductive filaments controlled by oxygen vacancies. Based on this Al/NiAl-LDHs/Al memristor, a D-type latch was constructed. A memtransistor with Si/SiO2/graphene oxide (GO)/Al/NiAl-LDHs/Al structure was built by connecting Al/NiAl-LDHs/Al memristor in series on the drain electrode of GO transistor. The memtransistor exhibits excellent gate controllability and resistive switching characteristics. Combined with its characteristics, we used the memtransistor to build a D-trigger and verify its memory logical function. The result shows the great potential of layered bimetallic hydroxide materials in the field of resistance switching memory and memory computing.

Switchable multifunctional knob elastic metasurface for arbitrary modulation of flexural waves

Manipulating elastic waves propagating in the desired manner has attracted substantial attention, and the metasurfaces offer the important ideas to achieve this goal. In particular, it will be more advantageous if wave function switching can be achieved without changing the microstructure of the metasurface. In the paper, a knob elastic metasurface is designed to realize the regulation of flexural wave covering the 0–2π range of phase shift by rotating the angle of the knob. When the metasurface is in the turn-on state, the angles of the knob at different positions can be adjusted reasonably though the generalized Snell's law to achieve several phenomena of anomalous refraction, beam focus, and non-paraxial self-acceleration of flexural wave in a wide frequency. And when the metasurface is placed in the turn-off state, the total reflection of the flexural wave can be realized, and then bidirectional vibration isolation can be achieved.

Integral input-to-state stability of switched delayed systems with delay-dependent impulses under generalized impulsive and switching scheme

This paper studies integral input-to-state stability (iISS) of a class of hybrid delayed systems with impulse and switching behavior, in which the delay-dependent impulse and switching behavior are allowed for asynchronous occurrence. Relative to admissible edge-dependent average dwell time (AED-ADT) concept of the switching signal, a fresh concept of admissible edge-dependent average impulsive interval (AED-AII) is proposed for the impulse signal. Several sufficient criteria for iISS are achieved by using multiple Lyapunov–Krasovskii functional (MLKF) tool, AED-ADT switching, and AED-AII schemes. An improved inequality that describing the relation among Lyapunov function continuous switching signal and discrete impulse is constructed, where the jump amplitude at discrete switching points and impulsive moments including delay-dependent part and delay-independent part are involved. Compared with existing results, our conclusions have the following novelties: (1) the influence of time delay existing in continuous dynamics and discrete impulse on the function part of L-K functional is dug out, which is less conservative; (2) the AED-AII scheme proposed in this paper is combined with the AED-ADT switching method, which contains a larger set of the impulsive and switching signal. Moreover, the stability criterion is suitable for the arbitrary time delay in situation that all the subsystems are destabilizing. Finally, an example is given to verify the validity of the results.

The Newborn's Reaction to Light as the Determinant of the Brain's Activation at Human Birth.

Developmental neuroscience research has not yet fully unveiled the dynamics involved in human birth. The trigger of the first breath, often assumed to be the marker of human life, has not been characterized nor has the process entailing brain modification and activation at birth been clarified yet. To date, few researchers only have investigated the impact of the extrauterine environment, with its strong stimuli, on birth. This ‘hypothesis and theory' article assumes the role of a specific stimulus activating the central nervous system (CNS) at human birth. This stimulus must have specific features though, such as novelty, efficacy, ubiquity, and immediacy. We propose light as a robust candidate for the CNS activation via the retina. Available data on fetal and neonatal neurodevelopment, in particular with reference to retinal light-responsive pathways, will be examined together with the GABA functional switch, and the subplate disappearance, which, at an experimental level, differentiate the neonatal brain from the fetal brain. In this study, we assume how a very rapid activation of retinal photoreceptors at birth initiates a sudden brain shift from the prenatal pattern of functions to the neonatal setup. Our assumption implies the presence of a photoreceptor capable of capturing and transducing light/photon stimulus, transforming it into an effective signal for the activation of new brain functions at birth. Opsin photoreception or, more specifically, melanopsin-dependent photoreception, which is provided by intrinsically photosensitive retinal ganglion cells (ipRGCs), is considered as a valid candidate. Although what is assumed herein cannot be verified in humans based on knowledge available so far, proposing an important and novel function can trigger a broad range of diversified research in different domains, from neurophysiology to neurology and psychiatry.

Switchable ultra-broadband absorption and polarization conversion metastructure controlled by light.

This article proposed a metastructure device that can realize polarization conversion (PC) and absorption function switching in the terahertz (THz) range based on the photoconductivity effect. The photoconductance is formed by exposing silicon to different intensities of light, then the PC and absorption function can be switched. At the same time, the absorption bandwidth is expanded by inserting air resonant cavities into the dielectric substrate, changing the thickness of the dielectric locally, and cutting rectangular slots at the metal bottom plate. When the device works as a polarization converter, linear-to-linear PC with a polarization conversion rate of over 90% at 0.96-1.47 THz can be achieved, and its relative bandwidth is 42%. And when the silicon conductivity is fixed at 3500 S/m through illuminating, the device switches to an ultra-broadband absorber with over 90% absorption at 0.75-1.73 THz and a relative bandwidth of 79%. The designed device can be applied efficiently in many fields, such as electromagnetic cloaking and communication.

Organic-inorganic hybrid phyllosilicate with switchable wettability induced by ultrasonication treatment

Materials with switchable wettability have attracted much attention because of its potential use in various applications. In this report, a novel switchable hydrophilic/hydrophobic organic-inorganic hybrid phyllosilicate was prepared by the self-assembly of vinyltriethoxysilane and calcium chloride. The structure of the hybrid phyllosilicate was a framework consisted of a calcium‑oxygen octahedral sheet sandwiched between two vinyl-silica tetrahedron sheets. The water contact angle (CA) at hydrophobic and hydrophilic states of hybrid phyllosilicate was 140.4° and 49.2°, respectively. The absorbed oil by hybrid phyllosilicate can be reversibly released in water after ultrasonication treatment for 30 min. On the surface of hybrid phyllosilicate, hydrophobic state of nanoflower (100–300 nm) morphology was switched to hydrophilic state of nanosheets (5–20 μm) after ultrasonication treatment. This novel structure of hybrid phyllosilicate expands the architecture concept for materials with controllable wettability, which can be applied in the construction of functional films, microfluidic switching, and ultrasonic responsive devices.

Realization of Multifunctional Metamaterial Structure Based on the Combination of Vanadium Dioxide and Graphene.

Combining tunable properties and various functionalities into a single metamaterial structure has become a novel research hotspot and can be used to tackle great challenges. The multifunctional metamaterial structure that combines absorption, linear-to-circular (LTC) polarization conversion, filtering and switching functions into a single metamaterial device was designed and investigated in this study. The switching of different functions can be achieved based on the phase transition of vanadium dioxide (VO2) and change of graphene chemical potential. When VO2 is in a metal state, the multi-frequency absorption and LTC polarization conversion can be achieved with different chemical potentials. When VO2 is in the insulator state and the polarization angle of incident wave is 45°, the device can be used to select or isolate the incident waves with different polarization states in the frequency region of 1.2–1.8 THz. Furthermore, when the chemical potentials are 0.05 eV and 1.2 eV, the corresponding transmissions of the TE-polarized wave demonstrate the opposite results, realizing the switching functions in the frequency region of 0.88–1.34 THz. In the frequency region above 2 THz, the multi-frequency rejection filter can be achieved. The designed switchable multifunctional metamaterial device can be widely implemented in radar monitoring and communication systems.

Dehydrogenative Esterification and Dehydrative Etherification by Coupling of Primary Alcohols Based on Catalytic Function Switching of an Iridium Complex

AbstractEsters and ethers are widely used in modern organic synthesis. In recent years, the synthesis of esters by the dehydrogenative coupling of primary alcohols has been reported to be an environmentally benign process. In this situations, if a single catalyst can be used for the synthesis of either esters or ethers by making slight alterations to the reaction conditions, the value of the synthetic methodology would increase. In this study, we successfully developed a new catalytic function switching system: not only dehydrogenative esterification but also dehydrative etherification under environmentally friendly conditions were accomplished by the employment of a single iridium catalyst based on catalytic function switching. Using benzyl alcohol as a starting material, the esterification product, benzyl benzoate, and the etherification product, dibenzyl ether, were obtained in 92 % and 89 % yields, respectively, by employing same iridium catalyst precursor bearing a dihydroxybipyridine ligand, under optimized conditions.

Threonine phosphorylation regulates the molecular assembly and signaling of EGFR in cooperation with membrane lipids.

The cytoplasmic domain of receptor tyrosine kinases (RTKs) plays roles as a kinase and a protein scaffold; however, the allocation of these two functions is not fully understood. Here, we analyzed the assembly of the transmembrane (TM)-juxtamembrane (JM) region of EGFR, one of the best studied members of RTKs, by combining single-pair fluorescence resonance energy transfer (FRET) imaging and a nanodisc technique. The JM domain of EGFR contains a threonine residue (T654) that is phosphorylated after ligand association. We observed that the TM-JM peptides of EGFR form anionic lipid-induced dimers and cholesterol-induced oligomers. The two forms involve distinct molecular interactions, with a bias toward oligomer formation upon threonine phosphorylation. We further analyzed the functions and oligomerization of whole EGFR molecules, with or without a substitution of T654 to alanine, in living cells. The results suggested an autoregulatory mechanism in which T654 phosphorylation causes a switch of the major function of EGFR from kinase-activating dimers to scaffolding oligomers.

Transcriptomic and histochemical analysis reveal the complex regulatory networks in equine chorioallantois during spontaneous term labor†.

The equine chorioallantois (CA) undergoes complex physical and biochemical changes during labor. However, the molecular mechanisms controlling these changes are still unclear. Therefore, the current study aimed to characterize the transcriptome of equine CA during spontaneous labor and compare it with that of normal preterm CA. Placental samples were collected postpartum from mares with normal term labor (TL group, n = 4) and from preterm not in labor mares (330days GA; PTNL group, n = 4). Our study identified 4137 differentially expressed genes (1820 upregulated and 2317 downregulated) in CA during TL as compared with PTNL. TL was associated with the upregulation of several proinflammatory mediators (MHC-I, MHC-II, NLRP3, CXCL8, and MIF). Also, TL was associated with the upregulation of matrix metalloproteinase (MMP1, MMP2, MMP3, and MMP9) with subsequent extracellular matrix degradation and apoptosis, as reflected by upregulation of several apoptosis-related genes (ATF3, ATF4, FAS, FOS, and BIRC3). In addition, TL was associated with downregulation of 21 transcripts coding for collagens. The upregulation of proteases, along with the downregulation of collagens, is believed to be implicated in separation and rupture of the CA during TL. Additionally, TL was associated with downregulation of transcripts coding for proteins essential for progestin synthesis (SRD5A1 and AKR1C1) and angiogenesis (VEGFA and RTL1), as well as upregulation of prostaglandin synthesis-related genes (PTGS2 and PTGES), which could reflect the physiological switch in placental endocrinology and function during TL. In conclusion, our findings revealed the equine CA gene expression signature in spontaneous labor at term, which improves our understanding of the molecular mechanisms triggering labor.

Heterotropic roles of divalent cations in the establishment of allostery and affinity maturation of integrin αXβ2.

SUMMARYAllosteric activation and silencing of leukocyte β2-integrins transpire through cation-dependent structural changes, which mediate integrin biosynthesis and recycling, and are essential to designing leukocyte-specific drugs. Stepwise addition of Mg2+ reveals two mutually coupled events for the αXβ2 ligand-binding domain—the αX I-domain—corresponding to allostery establishment and affinity maturation. Electrostatic alterations in the Mg2+-binding site establish long-range couplings, leading to both pH− and Mg2+-occupancy-dependent biphasic stability change in the αX I-domain fold. The ligand-binding sensorgrams show composite affinity events for the αX I-domain accounting for the multiplicity of the αX I-domain conformational states existing in the solution. On cell surfaces, increasing Mg2+ concentration enhanced adhesiveness of αXβ2. This work highlights how intrinsically flexible pH− and cation-sensitive architecture endows a unique dynamic continuum to the αI-domain structure on the intact integrin, thereby revealing the importance of allostery establishment and affinity maturation in both extracellular and intracellular integrin events.

LGP2 is essential for zebrafish survival through dual regulation of IFN antiviral response

SummaryIn mammals, LGP2 is the enigmatic RLR family member, being initially believed as an inhibitor of RLR-triggered IFN response but subsequently as an activator of MDA5 signaling and an inhibitor of RIG-I signaling. The contradiction happens to fish LGP2. Here, we generate a lgp2 loss-of-function (lgp2lof/lof) zebrafish mutant, which is highly susceptible to SVCV infection, displaying an initially decreased activation of IFN response and a following increased one. Mechanistically, zebrafish LGP2 functions as the essential activator of IFN response dependent on MDA5 at the early stage of viral infection but as a negative regulator by impairing mRNA levels of tbk1 and ikki at the late stage of viral infection. The function switch of LGP2 is related to cellular IFN production during viral infection. Our data demonstrate that zebrafish LGP2 is a key homeostatic regulator of IFN response and thus essential for zebrafish survival against SVCV infection.

Design of Innovation and Entrepreneurship Education Ecosystem in Universities Based on User Experience

The conventional college innovation and entrepreneurship education ecosystem is not considered to be designed for low energy consumption, and there is confusion in function switching, which leads to a large value of packet loss rate in system transmission. In this paper, we analyze the construction of college innovation and entrepreneurship education ecosystem and construct the scientific ecosystem of college innovation and entrepreneurship education based on user experience so as to realize college. At the same time, it takes into account the principle of green and low energy consumption of system hardware and software design, in which the hardware part selects S3C6410 RISC microcontroller as the core component to build the structure of educational ecological controller, connects a 16 bit buffer in parallel outside the controller, uses the buffer as the actual conversion port, specifies the function switching bearing interface, uses a protocol conversion chip, and designs the data acquisition circuit structure. The software part builds a model of user experience elements, sets to get an ecological interaction interface under the interoperability between the model and information data, and uses JAVA programming to realize functional modules according to the deviation of educational information shown by users. The experimental results show that the educational ecosystem designed in this paper has high data throughput, high fault tolerance, and low packet loss rate and system energy consumption, which verifies the effectiveness of the system.