Transient Network Research Articles

Age of onset modulates resting-state brain network dynamics in Friedreich Ataxia.

This magnetoencephalography (MEG) study addresses (i) how Friedreich ataxia (FRDA) affects the sub‐second dynamics of resting‐state brain networks, (ii) the main determinants of their dynamic alterations, and (iii) how these alterations are linked with FRDA‐related changes in resting‐state functional brain connectivity (rsFC) over long timescales. For that purpose, 5 min of resting‐state MEG activity were recorded in 16 FRDA patients (mean age: 27 years, range: 12–51 years; 10 females) and matched healthy subjects. Transient brain network dynamics was assessed using hidden Markov modeling (HMM). Post hoc median‐split, nonparametric permutations and Spearman rank correlations were used for statistics. In FRDA patients, a positive correlation was found between the age of symptoms onset (ASO) and the temporal dynamics of two HMM states involving the posterior default mode network (DMN) and the temporo‐parietal junctions (TPJ). FRDA patients with an ASO <11 years presented altered temporal dynamics of those two HMM states compared with FRDA patients with an ASO > 11 years or healthy subjects. The temporal dynamics of the DMN state also correlated with minute‐long DMN rsFC. This study demonstrates that ASO is the main determinant of alterations in the sub‐second dynamics of posterior associative neocortices in FRDA patients and substantiates a direct link between sub‐second network activity and functional brain integration over long timescales.

The effect of fire location and the reverse stack on fire smoke transport in high-rise buildings

In this paper, smoke transport in high-rise buildings through elevator shafts and stairwells is investigated for various fire location and stack effect conditions. For this purpose, a transient network model, Fire-STORM, is upgraded and used. The results are benchmarked by using a computational fluid dynamics (CFD) model. Six scenarios are tested, which are 1st floor, mid-floor, and top-most floor fires under normal stack (cold environment) and reverse stack (hot environment) conditions. For each scenario, the time history of pressures, temperatures, and soot mass fractions in the fire floors, elevator shafts, and stairwells and the average soot mass fraction in all stories of the building are presented. Overall, Fire-STORM has reasonably good accuracy compared to CFD with significantly faster computation times (90 s on a single core vs. 4 days on 32 cores in parallel). One of the intended uses of this fast low-order model is a data generation engine for neural network modeling of high-rise building fires. As such, one of the unique features of this work is the development of a realistic random heat release rate (HRR) modeling approach created using a Gaussian process.

Liquid-Liquid Phase Separation of the Green Mussel Adhesive Protein Pvfp-5 is Regulated by the Post-Translated Dopa Amino Acid.

The underwater adhesive prowess of aquatic mussels has been largely attributed to the abundant post-translationally modified amino acid l-3,4-dihydroxyphenylalanine (Dopa) in mussel foot proteins (MFPs) that make up their adhesive threads. More recently, it has been suggested that during thread fabrication, MFPs form intermediate fluidic phases such as liquid crystals or coacervates regulated by a liquid-liquid phase separation (LLPS) process. Here, it is shown that Dopa plays another central role during mussel fiber formation, by enabling LLPS of Pvfp-5β, a main MFP of the green mussel Perna viridis. Using residue-specific substitution of Tyrosine (Tyr) for Dopa during recombinant expression, Dopa-substituted Pvfp-5β is shown to exhibit LLPS under seawater-like conditions, whereas the Tyr-only version forms insoluble aggregates. Combining quantum chemistry calculations and solution NMR, a transient H-bonding network requiring the two hydroxyl groups of Dopa is found to be critical to enable LLPS in Dopa-mutated Pvfp-5β. Overall, the study suggests that Dopa plays an important role in regulating LLPS of MFPs, which may be critical to concentrate the adhesive proteins at the plaque/substrate interface and therefore produce a more robust adhesive. The findings also provide molecular-level lessons to guide biomanufacturing of protein-based materials such as bioadhesives and load-bearing fibers.

Chain breaking in the statistical mechanical constitutive theory of polymer networks

Elastomers are used in a wide range of applications because of their large strain to failure, low density, and tailorable stiffness and toughness. The mechanical behavior of elastomers derives mainly from the entropic elasticity of the underlying network of polymer chains. Elastomers under large deformation experience bonds breaking within the backbone chains that constitute the polymer network. This breaking of chains damages the network, can lead to material failure, and can be utilized as an energy dissipation mechanism. In the case of reversible bonds, broken chains may reform and heal the damage in the network. If the reversible bonds are dynamic, chains constantly break and reform and create a transient network. A fundamental constitutive theory is developed to model the mechanics of these polymer networks. A statistical mechanical derivation is conducted to yield a framework that takes in an arbitrary single-chain model (a Hamiltonian) and outputs the following: the single-chain mechanical response, the breaking and reforming kinetics, the equilibrium distribution of chains in the network, and the partial differential equations governing the deformation-coupled network evolution. This statistical mechanical framework is then brought into the continuum scale by using macroscopic thermodynamic constitutive theory to obtain a constitutive relation for the Cauchy stress. The potential-supplemented freely jointed chain (uFJC) model is introduced, and a parametric study of its mechanical response and breaking kinetics is provided. This single-chain model is then implemented within the constitutive framework, which we specialize and apply in two exemplary cases: the mechanical response and irreversible breakdown of a multinetwork elastomer, and the mechanical response of a dual crosslink gel. After providing a parametric study of the general constitutive model, we apply it to a hydrogel with reversible metal-coordination crosslinks. In several cases, we find that the breakdown of the network causes secondary physical mechanisms to become important and inhibit the accuracy of our model. We then discuss these mechanisms and indicate how our existing framework can be adjusted to incorporate them in the future.

Large-scale empirical study on the momentum equation’s inertia term

A common approach to reduce the Euler equations’ complexity for the simulation and optimization of gas networks is to neglect small terms that contribute little to the overall equations. An example is the inertia term of the momentum equation, which is said to be of negligible size under real-world operating conditions. However, this justification has always only been based on experience or single sets of artificial data points. This study closes this gap by presenting a large-scale empirical evaluation of the absolute and relative size of the inertia term when operating a real-world gas network. Our data consists of three years of fine-granular state data of one of the largest gas networks in Europe, featuring over 6,000 pipes with a total length of over 10,000 km. We found that there are only 120 events in which a subnetwork consisting of multiple pipes has an inertia term of high significance for more than three minutes. On average, such an event occurs less often than once every ten days. Therefore, we conclude that the inertia term is indeed negligible for real-world transient gas network control problems.

Oligonucleotide Phosphorothioates Enter Cells by Thiol‐Mediated Uptake

AbstractOligonucleotide phosphorothioates (OPS) are DNA or RNA mimics where one phosphate oxygen is replaced by a sulfur atom. They have been shown to enter mammalian cells much more efficiently than non‐modified DNA. Thus, solving one of the key challenges with oligonucleotide technology, OPS became very useful in practice, with several FDA‐approved drugs on the market or in late clinical trials. However, the mechanism accounting for this facile cellular uptake is unknown. Here, we show that OPS enter cells by thiol‐mediated uptake. The transient adaptive network produced by dynamic covalent pseudo‐disulfide exchange is characterized in action. Inhibitors with nanomolar efficiency are provided, together with activators that reduce endosomal capture for efficient delivery of OPS into the cytosol, the site of action.

Oligonucleotide Phosphorothioates Enter Cells by Thiol-Mediated Uptake.

Oligonucleotide phosphorothioates (OPS) are DNA or RNA mimics where one phosphate oxygen is replaced by a sulfur atom. They have been shown to enter mammalian cells much more efficiently than non‐modified DNA. Thus, solving one of the key challenges with oligonucleotide technology, OPS became very useful in practice, with several FDA‐approved drugs on the market or in late clinical trials. However, the mechanism accounting for this facile cellular uptake is unknown. Here, we show that OPS enter cells by thiol‐mediated uptake. The transient adaptive network produced by dynamic covalent pseudo‐disulfide exchange is characterized in action. Inhibitors with nanomolar efficiency are provided, together with activators that reduce endosomal capture for efficient delivery of OPS into the cytosol, the site of action.

Nonsteady fracture of transient networks: The case of vitrimer

We have discovered a peculiar form of fracture that occurs in polymer network formed by covalent adaptable bonds. Due to the dynamic feature of the bonds, fracture of this network is rate dependent, and the crack propagates in a highly nonsteady manner. These phenomena cannot be explained by the existing fracture theories, most of which are based on steady-state assumption. To explain these peculiar characteristics, we first revisit the fundamental difference between the transient network and the covalent network in which we highlighted the transient feature of the cracks. We extend the current fracture criterion for crack initiation to a time-evolution scheme that allows one to track the nonsteady propagation of a crack. Through a combined experimental modeling effort, we show that fracture in transient networks is governed by two parameters: the Weissenberg number [Formula: see text] that defines the history path of crack-driving force and an extension parameter Z that tells how far a crack can grow. We further use our understanding to explain the peculiar experimental observation. To further leverage on this understanding, we show that one can "program" a specimen's crack extension dynamics by tuning the loading history.

Temporally persistent networks of long-lived mixed wormlike micelles of zwitterionic and anionic surfactants

Rheometry, small-angle neutron scattering, and cryo-transmission electron microscopy were combined to investigate the structure and properties of mixed wormlike micelles (WLMs) of zwitterionic (oleylamidopropyl dimethyl betaine) and anionic (sodium dodecylsulfate) surfactants. This system demonstrates the formation of giant linear long-lived WLMs, which even at extremely low surfactant concentration reach a sufficient length to entangle with each other and form a three-dimensional temporally persistent network. Stability of these micelles can be due to electrostatic attraction between the headgroups of the anionic and zwitterionic surfactants and favorable volume/length hydrophobic ratio in the surfactant mixture. Heating of these systems leads to the transition of temporally persistent network with predominantly elastic properties into transient network exhibiting viscoelasticity, which is due to the shortening of long-lived WLMs. At increasing surfactant concentration, the long-lived linear micelles transform into fast-breaking branched micelles, which is due to the screening of electrostatic interactions by salt released from the dissociated surfactant molecules. The transition results in the drop of viscosity and approaches the system to the behavior of Maxwell fluid with a single relaxation time. The observed structural transitions strongly affecting the rheological properties can be exploited in various applications of zwitterionic surfactants.

Flexible Vertical Photogating Transistor Network with an Ultrashort Channel for In‐Sensor Visual Nociceptor

AbstractHumans can clearly perceive surroundings efficiently while consuming little energy because of human intelligence and powerful vision system. Thus, it has been a long‐sought dream for human beings to build such an energy‐efficient artificial intelligent vision system with emerging devices. Unfortunately, a wearable optoelectronic device for visual nociceptor systems, regarded as a key bionic function to protect the vision, remains to be developed so far. Herein, using the vertical coplanar‐multiterminal flexible transient photogating transistor network with a 3 nm ultrashort channel, a wearable artificial vision system with painful‐perceptual abilities is successfully demonstrated for flexible electronic‐skin (e‐skin) applications. The device not only has the ability of ultrafast transient physical disappearance of only 60 s for information security but also establishes a flexible optical in‐sensor visual nociceptor (ISVN) e‐skin. The optical transition from short‐time memory to long‐time memory of visual memory is educed by a strong photogating effect, and the higher‐level‐graded optical painful alarm‐sensing system is also demonstrated by this flexible artificial e‐skin. Moreover, the proposed devices will achieve painful light sensitization under different spatiotemporal color patterns to avoid external secondary injuries. It provides a good opportunity for future intelligent e‐skin taking advantage of its intriguing visual pain‐perceptual abilities.

Bidirectional Solid-State Circuit Breaker Using Super Cascode for MV SST and Energy Storage Systems

Solid-state transformers (SSTs) are developing as highly efficient interfaces in renewable energy, transport, and energy storage systems (ESSs). However, performance limitations, such as overvoltage sensitivity and fault handling capabilities, have slowed widespread adoption. Although SSTs are developing added capabilities for fault management, the required response speed and overdesign introduces added costs, particularly in protection of ultralow inductance systems, such as those sourced by ESSs. With increased use of power electronics, the power distribution systems are speeding up having shorter fault propagation delays and higher fault currents. This creates a need for alternative approaches to MV system protection. This article describes a bidirectional solid-state circuit breaker (BSSCB) based on a new SiC SuperCascode power switch, and a multilayered transient absorption network. This article studies transient heat transfer in the switch and provides a redefinition of the fuse curve as applied to the BSSCB suitable for digital control. This article identifies critical fault issues, discusses the impact on critical design points of the SuperCascode for a BSSCB, and provides design calculations for a complete 10-kV/300-A/3 X breaker, including the SuperCascode module. A scaled 6-kV/10-A/7 X SuperCascode is fabricated and tested to demonstrate switch response of <60 ns with fault isolation in 200 ns.

Transient neural network dynamics in cognitive ageing

It is important to maintain cognitive function in old age, yet the neural substrates that support successful cognitive ageing remain unclear. One factor that might be crucial, but has been overlooked due to limitations of previous data and methods, is the ability of brain networks to flexibly reorganize and coordinate over a millisecond time-scale. Magnetoencephalography (MEG) provides such temporal resolution, and can be combined with Hidden Markov Models (HMMs) to characterise transient neural states. We applied HMMs to resting-state MEG data from a large cohort (N=595) of population-based adults (aged 18-88), who also completed a range of cognitive tasks. Using multivariate analysis of neural and cognitive profiles, we found that decreased occurrence of “lower-order” brain networks, coupled with increased occurrence of “higher-order” networks, was associated with both increasing age and decreased fluid intelligence. These results favour theories of age-related reductions in neural efficiency over current theories of age-related functional compensation, and suggest that this shift might reflect a stable property of the ageing brain.

Phishing Webpage Detection using Hybrid Features and Deep Learning Techniques

Phishing is a sort of online assault that endeavors to cheat delicate data of organization clients. Current phishing website page discovery strategies primarily utilize manual component assortment, and there are issues that include extraction is muddled and the conceivable connection between's highlights can't be stayed away from. To tackle the issues, another phishing site page location model is proposed, among which the primary segments are programmed taking in portrayals from multi-perspectives highlights through portrayal learning and extricating highlights by mixture profound learning organization. Initially, the model treats URL, HTML page substance, and document object model design of pages as character arrangements individually, also, utilizes portrayal learning innovation to consequently get familiar with the portrayal of the pages; at that point, sends different portrayals to a half breed profound learning network made out of a convolutional neural network also, a bidirectional long and transient memory network through various channels to separate neighborhood and worldwide highlights, and utilize the consideration component to fortify the influence of significant highlights; finally, the yield of various channels is combined to acknowledge classification expectation. Through four arrangements of trials to check the recognition impact of the model, the outcomes show that the general classification impact of the model is superior to the current exemplary phishing site page discovery strategies, the exactness arrives at 98.05%, and the bogus positive rate is just 0.25%. It is demonstrated that the techniques of extricating website page highlights from all angles through portrayal learning and cross breed profound learning organization can successfully improve the discovery impact of phishing site pages..

FCNR: Fast and Consistent Network Reconfiguration with low latency for SDN

Software-defined network (SDN) is one of the important technologies to achieve the customization of network services. The key to realize a highly adaptive SDN, which can respond to the changing demands or recover after network failure in a short period of time, is to update the configuration effectively. However, the inconsistent configuration update may lead to transient and incorrect network behaviors and long reconfiguration time between current configuration and target configuration may degrade undesired network performance. Most of the existing works to reduce the network reconfiguration time focus on the consistent update between current configuration and target configuration, and ignore the impact of different target configurations on network reconfiguration time. Therefore, reducing the network reconfiguration time needs to consider not only the consistent update between current configuration and target configuration, but also the impact of different target configurations. In this paper, we first analyze the impact of different target configuration of the control plane on the update operation in the forwarding rules of the data plane. Then, we formulate the shortest configuration path (SCP) problem to get the path with the shortest configuration time and propose the shortest deployment time path selection (SPS) algorithm to obtain the target configuration in the light of different rules deployment time. Subsequently, we propose the consistent scheduling update (CSU) algorithm to solve the consistency conversion from the current configuration to the target configuration. Finally, experimental results demonstrate that our algorithms can reduce the network reconfiguration time up to 39% compared with previous SDN consistent update methods while keeping the similar consistency.

Reexamining the role of intercrystalline links in the II-I phase transition of Poly(1-butene)

Despite being studied extensively, the role of intercrystalline links has not been elucidated completely. To clarify its role, two kinds of different lengths of poly (1-butene) chains were blended with different proportions, among which only the long chain was able to form intercrystalline links. Phase transitions of these blends were monitored with time-resolved FTIR. Surprisingly, when the content of long chains reached 30% or 40%, phase transition rates were even slower than they existed alone, indicating phase transition was suppressed greatly by long chains. Adding a minority of short chains actually would also slow down the phase transition, though the effect was not as obvious as long chains. Estimation indicates that the change of enthalpy cannot compensate for the loss in conformational entropy in II-I phase transition. To ensure continuous proceeding of II-I phase transition, the role of amorphous chains is indispensable in the quiescent phase transition. Nevertheless, the role of intercrystalline links should not be undue stressed either. Analysis indicates that a transient amorphous network exists in the blends, consisting of different sizes of amorphous coils. Long chains can form larger coils because of intercrystalline links, while small coils are most likely from individual short chains. Entanglements exist between these amorphous coils, stabilizing the transient network, which would also affect phase transition significantly. When a minority of short chains are added, stress on one side of some big coils reduces. The big coils deviate from previous mass centers, slowing down its internal stress on form II crystal and thus its phase transition rate. Conversely, when a minority of long chains are added, big coils not only would lead small coils deviating from their previous mass centers, but also slow down contraction of the small coils through the entanglement, leading to a larger decrease in form I nuclei. The roles of intercrystalline links and entanglement should be considered simultaneously.

Effect of conductive carbon black on electrical conductivity and performance of tire tread compounds filled with carbon black/silica hybrid filler

AbstractFor green tires, carbon black (CB) is partially replaced by silica (SiO2) in the tread formula in order to improve wet grip (WG) and fuel saving efficiency (FSE). However, such replacement inversely affects electrical conductivity of a tire resulting a greater potential for static shock or electrostatic ignition. This work aimed to improve electrical conductivity of the tread compound by partially replacing either CB or SiO2 by 0–12 phr of conductive carbon black (CCB) (with replacing ratio of 2:1) and investigating the effect of such replacement on the tire performance. Although the partial replacement of CB or SiO2 by CCB increased the magnitude of transient filler network resulting in the negative effects on heat build‐up, WG and FSE of the tread vulcanizates, it significantly improved electrical conductivity. Surface resistivity decreased sharply when CB or SiO2 was replaced by 3 phr of CCB, revealing the point of percolation threshold. In addition, the partial replacement of CB or SiO2 by CCB did not cause significantly change of both hardness and tensile properties. At any given CCB loading, the SiO2 replacement provided greater surface conductivity and higher abrasion resistance with lower WG and FSE than the CB replacement.

Thermal network modeling of tunnel cable considering circumferential heat transfer and tunnel curvature

Taking wind direction and flow separation into account, the circumferential temperature difference of cable laid in forced-ventilation tunnel is investigated. Combining the heat conduction, the convection and the radiation, the formula calculating the thermal resistance is derived, followed by cable thermal network model in tunnel. The circumferential heat transfer and temperature profile for tunnel cable is analyzed. The results indicate that the temperature of cable is not only transmitted radially, but also circumferentially. The temperature on the leeward side is higher than that on the windward side. As the load increases, the circumferential temperature difference rises. The larger the wind direction angle, the smaller the temperature difference. When the angle is greater than 40°, continue to increase the angle does not have a great impact on the heat dissipation and temperature difference. It suggests that the temperature calculated by IEC-60287 is conservative as it does not take account of multi-factor interactions. The transient thermal network is also established.

An Ultrasoft Self-Fused Supramolecular Polymer Hydrogel for Completely Preventing Postoperative Tissue Adhesion.

The intermolecular H-bonding density heavily influences the gelation and rheological behavior of hydrogen-bonded supramolecular polymer hydrogels, thus offering a delicate pathway to tailor their physicochemical properties for meeting a specific biomedical application. Herein, one methylene spacer between two amides in the side chain of N-acryloyl glycinamide (NAGA) is introduced to generate a variant monomer, N-acryloyl alaninamide (NAAA). Polymerization of NAAA in aqueous solution affords an unprecedented ultrasoft and highly swollen supramolecular polymer hydrogel due to weakened H-bonds caused by an extra methylene spacer, which is verified by variable-temperature Fourier transform infrared (FTIR) spectroscopy and simulation calculation. Intriguingly, poly(N-acryloyl alaninamide) (PNAAA) hydrogel can be tuned to form a transient network with a self-fused and excellent antifouling capability that results from the weakened dual amide H-bonding interactions and enhanced water-amide H-bonding interactions. This self-fused PNAAA hydrogel can completely inhibit postoperative abdominal adhesion and recurrent adhesion after adhesiolysis in vivo. This transient hydrogel network allows for its disintegration and excretion from the body. The molecular mechanism studies reveal the signal pathway of PNAAA hydrogel in inhibiting inflammatory response and regulating fibrinolytic system balance. This self-fused, antifouling ultrasoft supramolecular hydrogel is promising as a barrier biomaterial for completely preventing postoperative tissue adhesion.

Sex differences in functional network dynamics observed using coactivation pattern analysis

ABSTRACT Sex differences in the organization of large-scale resting-state brain networks have been identified using traditional static measures, which average functional connectivity over extended time periods. In contrast, emerging dynamic measures have the potential to define sex differences in network changes over time, providing additional understanding of neurobiological sex differences. To meet this goal, we used a Coactivation Pattern Analysis (CAP) using resting-state functional magnetic resonance imaging data from 181 males and 181 females from the Human Connectome Project. Significant main effects of sex were observed across two independent imaging sessions. Relative to males, females spent more total time in two transient network states (TNSs) spatially overlapping with the dorsal attention network and occipital/sensory-motor network. Greater time spent in these TNSs was related to females making more frequent transitions into these TNSs compared to males. In contrast, males spent more total time in TNSs spatially overlapping with the salience network, which was related to males staying for longer periods once entering these TNSs compared to females. State-to-state transitions also significantly differed between sexes: females transitioned more frequently from default mode network (DMN) states to the dorsal attention network state, whereas males transitioned more frequently from DMN states to salience network states. Results show that males and females spend differing amounts of time at rest in two distinct attention-related networks and show sex-specific transition patterns from DMN states into these attention-related networks. This work lays the groundwork for future investigations into the cognitive and behavioral implications of these sex-specific network dynamics.

Reliability optimization design of deformation of CNC lathe spindle considering thermal effect

Angular contact ball bearings are widely used in the field of rotating machinery due to their obvious advantages such as relatively good positioning accuracy, high speed rotating performance and low cost, which have already become the most important transmission components. The heterogeneous thermal deformation caused by the high speed effect of bearing parts will lead to excessive noise and even gluing, which can further significantly reduce the machining accuracy of machine tool. Therefore, it is vital to improve the deformation resisting capability and operational reliability of the whole system. For this purpose, this paper presents a reliability model for computerized numerical control (CNC) lathe spindle by considering thermal effect. A five-degree-of-freedom quasi-static model considering thermal deformation is firstly proposed to calculate contact load and contact angle. Then the transient thermal network method is used to solve the temperature value of multi-node spindle-bearing system, and the validity of the proposed model is verified by experiments at different speeds. Next the modified first-order and second-moment method (FOSM) is used to calculate the reliability and reliability sensitivity of CNC lathe spindle deformation model considering thermal effect. Finally, the constrained nonlinear optimization method for the reliability model is proposed and applied to CNC lathe spindle. The results show that the reliability of the optimized model is significantly improved and the reliability robustness is enhanced.