Cyclic Dependence Research Articles

Numerical Simulations of Carbon-Fibre Impregnation with a Polymer as an Anisotropic Permeability Medium.

The impregnation process of carbon fibres with polymers is challenging to model due to the system's complexity, particularly concerning the following aspects: the complex rheology of the polymeric matrices and the presence of solid, continuous fibres, both with anisotropic properties, and the interaction between solid and fluid, which can change the displacement of fibres into a cyclic dependence. In this work, an interesting approach was considered by setting the fibres as a porous medium whose properties were calculated with microscale/macroscale cycle modelling. In the microscale modelling stage, two main assumptions can be made: (i) a homogeneous distribution with a representative cell or (ii) a stochastic distribution of fibres. The solution to the abovementioned flow and fibre distribution problem can severely differ with only a slight change in a single parameter for a given set of processing parameters. Therefore, the influence of some of them during the fibre impregnation process was evaluated, allowing a shortcut for the polymer through a gap between fibres and the bottom wall of the extrusion die. The range of investigated values regarding the gap enables one to cover good impregnation conditions up to the occurrence of the shortcut and consequent poor impregnation quality. These studies were performed with numerical simulations with circa 126,000 degrees of freedom, considering the discretisation mesh elements and the unknowns (pressure and two velocity components).

SAT186 Young Patient With Primary Hyperparathyroidism And Mutation Of CDKN1B Gene MEN 4 Variant

Abstract Disclosure: J.J. Faria Briceno: None. S.S. Jande: None. T. Lairmore: None. R.R. Yatavelli: None. Background: Parathyroid adenomas are the most common cause of primary hyperparathyroidism (PHPT)accounting for 80-85% of the cases. PHPT most commonly manifests between 50-60 years of age and when it presents at younger age, it can be associated with inherited genetic conditions like multiple endocrine neoplasia or Hyperparathyroid Jaw tumor syndrome. Clinical Case: A 34-year-old male without significant past medical history was noted to have elevated serum calcium on routine lab work and was advised to promptly go to the emergency room for further evaluation. In the ED, the patient’s corrected calcium was 13.8 mg/dL (normal range 8.7 - 10.5 mg/dL), ionized calcium elevated at 1.77 mmol/L (normal range 0.90 - 1.20 mmol/L), PTH was 786.2 pg/mL (normal range 9 - 77 pg/mL). The patient denied any history of fractures, kidney stones or bone pain. Patient was treated medically with IV fluids and calcium lowering agents. Given the elevated PTH, ultrasonography of the neck was done which revealed an oval, hypoechoic lesion measuring 1.2 x 2.25 cm with increased vascular flow posterior to the right thyroid lobe consistent with parathyroid adenoma. Parathyroidectomy was performed with excision of right inferior parathyroid adenoma measuring 2.7 x 1.2 x 0.6 cm (1.25 grams). The preoperative PTH level was 997.7 pg/mL, which rapidly improved 20 minutes post tumor excision to 75.9 pg/mL, a 90% fall in PTH level suggestive of successful tumor excision. The patient’s post-operative period was uneventful. Considering the very young age of presentation; hyperparathyroidism genetic panel was obtained to rule out any inherited conditions like MEN1 or Hyperparathyroid Jaw tumor syndrome. Genetic testing revealed a germline missense mutation in CKDN1B (variant c.287C &gt, heterozygous) and classified as Variant of Uncertain significance). Mutations in the cyclic dependence kinase inhibitor 1B (CDKN1B) have been identified as the culprit for tumor growth seen in multiple endocrine neoplasia 4. MEN4 is a rare autosomal dominant endocrine tumor syndrome characterized by hyperparathyroidism and pituitary adenomas. The variant described in our patient has classically not been associated with other tumors and the available evidence is currently insufficient to determine the role of this variant in disease and hence classified as Variant of Uncertain Significance. Conclusion: Genetic testing should be considered in patients with primary hyperparathyroidism who present at very young age or have multiglandular disease. Our patient does not have any other classic features of MEN 4 and as the genetic mutation is classified as Variant of Uncertain Significance, patient would be monitored clinically, and caution exercised before using this result to inform clinical management decisions. Presentation: Saturday, June 17, 2023

Electrical cycling of Cu-PMNZT multilayer co-fired ceramic actuators

The electric cycling characteristics of Cu/0.2(PbMg1/3Nb2/3O3)-0.8(PbZr0.475Ti0.525O3) (PMNZT) multilayer ceramic actuators were investigated. Cu/PMNZT co-fired multilayer actuators were fabricated by conventional tape casting, lamination, and sintering at 950 °C in air with subsequent annealing at 225 °C or 400 °C under a hydrogen atmosphere. In such processes, annealing of the multilayer samples under a reducing atmosphere is an important factor in controlling the piezoelectric performance. Unipolar and bipolar electric fields were applied to the actuators to investigate the fatigue behavior of the multilayer ceramic actuators. The sample annealed at 400 °C showed significant degradation in the effective electromechanical coupling coefficient (keff) and dynamic piezoelectric constant (d33*) after 1 × 108 electrical cycles, while the sample annealed at 225 °C showed less degradation. X-ray diffraction and X-ray photoelectron spectroscopy analyses were performed to evaluate the difference in crystalline structures as a function of annealing temperature. The keff, d33*, polarization, and strain were measured and evaluated as a function of the number of cycles. The cyclic dependence of strain was fitted to a linear logarithmic stretched exponential law. The significant degradation of the sample annealed at 400 °C is attributed to the reorientation of oxygen vacancies formed upon annealing, which gives a rise to internal field in the ceramic layer. The degraded performance of cycled sample was refreshed by a heating at 500 °C in air.

Modeling for cyclic plasticity and rate dependence of metal materials with a new non-unified viscoplasticity model

The classic unified viscoplasticity model has achieved great success in areas such as cyclic plasticity, time-dependent behavior, and creep–fatigue interaction. However, the unified viscoplasticity model may be inadequate to describe inelastic strain rate with static recovery term. Our previous study [Chen, Kitamura, Feng (Int J Fatigue 112:70–77, 2018)] of 316L stainless steel has shown that adding a static recovery term predicts an accelerating creep strain rate in the creep–relaxation interaction tests, which is inconsistent with the experimental test results. In this study, a modified non-unified viscoplasticity (NUV) model is proposed based on the mechanism of viscous glide. The parameter determination process and the role of different parts of the model are illustrated using experimental data drawn from Al 5083; then, the proposed model is verified by simulating the test of 316L stainless steel. The modeling results show that the proposed NUV model accurately predicts the strain rate evolution during the creep–relaxation interaction tests and other behaviors, i.e., cyclic plasticity and loading rate sensitivity. As with fewer parameters and more concise equations, the proposed NUV model is a good choice for engineering applications.

Examination of the crystallization process at the liquid-crystal interface during nanowire growth

Using Monte Carlo simulation and analytical description we studied the variation of catalyst drop composition during III–V nanowire formation via the vapor-liquid-solid growth mechanism. During a layer-by-layer growth mode, a cyclic dependence of arsenic concentration on the growth time in a metal drop was observed. The time shifts between the nucleation of a new layer at the liquid-solid interface and the arsenic concentration maximum in CAs(t) and the time shifts between the complete monolayer formation and the arsenic concentration minimum were demonstrated. The reason of these time shifts is the nonmonotonic time dependence of the growing 2D island perimeter.

Ratcheting assessment of low yield point steel BLY160: Experimental analysis and constitutive modelling

In this study, the ratcheting behaviour of low-yield-point steel BLY160 is evaluated via experimental investigation and constitutive modelling. A set of uniaxial asymmetrical cyclic loading tests in the strain- and stress-controlled modes is conducted to analyse the ratcheting response and stress relaxation, respectively. The effect of cyclic hardening and dependence on loading path are discussed to characterize the ratcheting behaviour. BLY160 steel is observed to exhibit a multi-stage evolution of ratcheting response with a significant cyclic hardening effect. However, the traditional Chaboche model calibrated according to the symmetric cyclic straining tests is observed to overestimate the cyclic hardening when predicting ratcheting, and might lead to an elastic shakedown under asymmetric cyclic stressing simulation. To overcome this disadvantage, a modified model based on the combined hardening rule is proposed; which introduces a new internal variable to distinguish the strain hardening under different loading paths. Hence, the interaction between the cyclic hardening and ratcheting behaviour can be accurately described. The accuracy of the modified model is validated by the close agreement between the simulation results and the experimental responses. The results verify that the proposed model is capable of simulating cyclical hardening, ratcheting, and stress relaxation behaviours for the test cases.

Cyclic plasticity and thermomechanical alleviation in titanium alloys

Cyclic behaviour of titanium alloy IMI834 has been investigated with a new thermo-mechanically coupled discrete dislocation plasticity formulation, integrated with experimental observation. The mechanistic basis of the cyclic loading dependence is shown to be the establishment of dislocation pileups and back stress development such that on partial unloading, reversed strain occurs by thermally-activated dislocation escape and reverse glide during a secondary stress hold. Anomalous cyclic strain accumulation in both isothermal and anisothermal stress-loaded alloy IMI834 is explained by the reversed straining and dislocation structure re-arrangement mechanisms. The mechanisms also provide the underpinning explanation for the beneficial effect of elevated temperature excursions in diminishing cyclic creep accumulation and hence reducing dwell fatigue sensitivity in titanium alloys by thermal alleviation.

Tumour initiation, store-operated calcium entry (SOCE) and apoptosis: cyclic nucleotide dependence.

Chemical instigators and modulators of tumourigenesis influence cell signal transduction pathways. Cyclic nucleotides and steroid hormones may contribute to the process of carcinogenesis or provide protection via apoptotic mechanisms. Although several pharmacologic classes of compounds influence cyclic nucleotide levels markedly, less is known about the class effects of promoters and blockers of tumourigenesis and apoptosis. This molecular modeling study uses cyclic nucleotide templates to investigate relative molecular similarity within compounds modulating tumourigenesis and apoptosis. Findings, in respect of superimposition and molecular fit of the investigated compounds, are related to their individual effects on cyclic nucleotide pharmacology. Modulators of tumourigenesis and estrogen receptor sub-type ligands relate to cyclic nucleotide structure. Estradiol and GPER ligands provide a similar pattern of fit to adenine nucleotide. Chemically diverse modulators of apoptosis, including K+ channel ligands, fit to different components of cyclic nucleotide structure. Compounds modulating Ca2+ entry and IP3 receptors relate structurally to the nucleotide dioxaphosphinin moiety. Relative molecular similarity within the structures of apoptosis and tumourigenesis modulators identifies a unifying property within chemically disparate compounds. The ubiquitous generation of oxidative stress and ROS in cells by apoptosis modulating compounds may relate to the disruption of cyclic nucleotide regulated homeostasis mechanisms.

Synchronized Progress in Interconnection Networks (SPIN): A New Theory for Deadlock Freedom

Routing deadlocks, i.e., a cyclic dependence between buffered packets, are a fundamental network design challenge. Existing solutions require resource over provisioning. We propose a new theory for deadlock freedom, Synchronized Progress in Interconnection Networks (SPIN) that solves the problem through coordinated movement of deadlocked packets.

Cyclic Supercooling of Liquid Bismuth Drops during Solidification

The laws of changing the presolidification supercooling of bismuth drops during continuous thermal cycling were studied by thermal analysis in the temperature–time coordinates. A sawtooth cyclic dependence of the supercooling on the sequence of heating and cooling cycles, which is described by a Fourier function, is detected. An expression is derived for the energy of coagulation of nuclei, and it is used to find a relation between the experimental and calculated supercoolings. The obtained results are interpreted in terms of a cluster-coagulation solidification model and the anomalous properties of bismuth in melting and solidification.

Modelling the photosynthetic electron transport chain in Nannochloropsis gaditana via exploitation of absorbance data

The development of mathematical models describing the photosynthetic apparatus of microalgae is paramount to gain deeper knowledge of the involved biological process and enable optimisation of cultivation conditions. This paper presents a dynamic model of the entire photosynthetic apparatus including the photosystems I (PSI) and II (PSII), the electron carriers between the two photosystems (plastoquinone, cytochrome b6f and cytochrome c6) and the final electron acceptor complex, the ferredoxin. In vivo measurements of PSI oxidation dynamics at different light intensities for the microalga Nannochloropsis gaditana have been exploited to develop and calibrate the model. The model has been experimentally identified and proved to be capable of accurate predictions of both linear and cyclic electron flows dependence on light intensity.

Cyclic dependence, vertical integration, and innovation: The case of Japanese electronics sector in the 1990s

The architecture of a firm's network of transactions in its surrounding business ecosystem may affect its innovation performance. Here we proximate a business ecosystem as a transaction network among firms. Specifically, we analyze how the innovation performances of the firms are associated with their network positions and vertical structures in the transaction network, using the data for the Japanese electronics sector in the early 1990s. The results show that, a firm's participation in inter-firm transaction cycles, instead of sequential transactional relationships, is positively and significantly associated with its innovation performance for vertically integrated firms. Within cycles, vertically integrated firms have better innovation performances than vertically specialized firms. Vertically integrated firms that participate in cycles have the best innovation performances in the Japanese electronics sector. These findings provide strategic implications and guidance for firms to design and manage their vertical structure and transaction network position.

Mechanism for the inhibition of the cAMP dependence of HCN ion channels by the auxiliary subunit TRIP8b

TRIP8b, an accessory subunit of hyperpolarization-activated cyclic nucleotide-gated (HCN) ion channels, alters both the cell surface expression and cyclic nucleotide dependence of these channels. However, the mechanism by which TRIP8b exerts these dual effects is still poorly understood. In addition to binding to the carboxyl-terminal tripeptide of HCN channels, TRIP8b also binds directly to the cyclic nucleotide-binding domain (CNBD). That interaction, which requires a small central portion of TRIP8b termed TRIP8bcore, is both necessary and sufficient for reducing the cAMP-dependent regulation of HCN channels. Here, using fluorescence anisotropy, we report that TRIP8b binding to the CNBD of HCN2 channels decreases the apparent affinity of cAMP for the CNBD. We explored two possible mechanisms for this inhibition. A noncompetitive mechanism in which TRIP8b inhibits the conformational change of the CNBD associated with cAMP regulation and a competitive mechanism in which TRIP8b and cAMP compete for the same binding site. To test these two mechanisms, we used a combination of fluorescence anisotropy, biolayer interferometry, and double electron-electron resonance spectroscopy. Fitting these models to our fluorescence anisotropy binding data revealed that, surprisingly, the TRIP8b-dependent reduction of cAMP binding to the CNBD can largely be explained by partial competition between TRIP8b and cAMP. On the basis of these findings, we propose that TRIP8b competes with a portion of the cAMP-binding site or distorts the binding site by making interactions with the binding pocket, thus acting predominantly as a competitive antagonist that inhibits the cyclic-nucleotide dependence of HCN channels.

Scheduling real-time systems with cyclic dependence using data criticality

The increase of interdependent components in avionic and automotive software rises new challenges for real-time system integration. For instance, most scheduling and mapping techniques proposed in the literature rely on the availability of the system’s DAG representation. However, at the initial stage of system design, a dataflow graph (DFG) is generally used to represent the dependence between software components. Due to limited software knowledge, legacy components might not have fully-specified dependencies, leading to cycles in the DFG and making it difficult to determine the overall scheduling of the system as well as restrict access to DAG-based techniques. In this paper, we propose an approach that breaks cycles based on the assignment of a degree of importance and that with no inherent knowledge of the functional or temporal behaviour of the components. We define a “criticality” metric that quantifies the effect of removing edges on the system by tracking the propagation of error in the graph. The approach was reported to produce systems $$(56 \pm 14)\%$$ less critical than other methods. It was also validated on two case studies; a data modem and an industrial full-mission simulator, while ensuring the correctness of the system is maintained.

Name analysis for modern languages: a general solution

SummaryClassical strategies for matching identifier uses with declarations cannot handle the complexities of modern languages: arbitrarily qualified superclass names, cyclic dependence among lookup operations, and contextual access constraints. We have developed a language‐independent algorithm and supporting data structure that overcome these problems. A well‐defined interface allows introduction of arbitrary code to enforce language‐specific constraints within the basic lookup operations. This paper explains the limitations of the classical strategies, presents the concepts on which our approach is based, and showcases an implementation based on attribute grammars. We explore the major issues through a series of examples and show how one can deal with those issues in a general framework. Many of the issues are specific to a particular language, and in those cases, we explain the solutions that our general interface supports. Although attribute grammars simplify the task of incorporating the model into a compiler, the model itself is completely independent of attribute grammars. We validated our model by using an implementation to process programs in several representative languages. In particular, we mechanically compared the results produced by that implementation with those produced by the Java SE 8 compiler on complete Java programs that are in general use. Performance data obtained during this processing show that our implementation is efficient. Copyright © 2017 John Wiley & Sons, Ltd.

Wireless Service Provider Selection and Bandwidth Resource Allocation in Multi-Tier HCNs

In this paper, we study the inter-linked problems of wireless service provider (WSP) selection of users and bandwidth allocation of WSPs in multi-tier heterogeneous cellular networks employing the approach combining stochastic geometry and game theory. In particular, the expected average user achievable rate is calculated by modeling the distributions of users and base stations (BSs) as independent homogeneous Poisson point processes. Moreover, a hierarchical game framework is presented to model the complicated interactions among users and WSPs. Wherein, the evolutionary game, non-cooperative game, and multi-leader multi-follower Stackelberg game models are, respectively, adopted to formulate the competition among users, competition among WSPs, and cyclic dependence between users and WSPs. According to backward induction, the formulated Stackelberg game would be solved after the formulated evolutionary game and non-cooperative game are sequentially studied. For the evolutionary game, both the closed-form expression and the asymptotically stability of its evolutionary equilibrium (EE) were analyzed. Then, conditioned on the obtained EE, the existence of Nash equilibrium (NE) for the non-cooperative bandwidth allocation game is established; furthermore, a sufficient condition for the uniqueness of the NE is derived. Finally, extensive simulation results verify both the validity of our analysis and the effectiveness of the proposed scheme.

Cyclic temperature dependence of electrical conductivity in polyanilines as a function of the dopant and synthesis method

Most of the studies dealing with polyanilines (PANIs) are focused on electrochemical polymerization; however, chemical polymerization is more suitable for large–scale production. In order to develop commercially viable, clean, effective materials for thermal sensor devices, temperature dependent electrical response has been studied in PANIs obtained by simple, low-cost synthesis conditions, transferable to industrial processing. PANIs doped with HCl, dodecylbenzene sulfonic acid (DBSA) and sodio-5-sulfoisophtalic acid (NaSIPA) were prepared by chemical oxidative polymerization, through direct and indirect routes of synthesis. TEM images disclosed formation of nanorods and microfibrils. Microstructural analysis confirmed differences in doping level and crystallinity which were related with the PANI conductivity.Two PANI-DBSA synthesized by direct and indirect methods, exhibit the best conductivity retention up to 150°C. In cyclic tests, they show excellent performance after 4 heating-cooling cycles up to 70°C. The amplitude of electrical response for PANI-DBSA obtained by direct synthesis is twice the value of PANI-DBSA prepared by indirect route. Conversely, the latter displays slightly better repeatability due to its lower moisture content. This study suggests that both PANI-DBSA are suitable for use in electronic applications, under ambient conditions below 150°C, and are promising materials for temperature sensor applications.

Cyclic Dependence, Vertical Integration, and Innovation

The architecture of a firm’s network of transactions in its surrounding business ecosystem may affect its innovation performance. Here we proximate a business ecosystem as a transaction network among firms. Specifically, we analyze how the innovation performances of the firms are associated with their network positions and vertical structures in the transaction network, using the data for the Japanese electronics sector in the early 1990s. The results show that, a firm’s participation in inter-firm transaction cycles, instead of sequential transactional relationships, is positively and significantly associated with its innovation performance for vertically integrated firms. Within cycles, vertically integrated firms have better innovation performances than vertically specialized firms. Vertically integrated firms that participate in cycles have the best innovation performances in the Japanese electronics sector. These findings provide strategic implications and guidance for firms to design and manage their vertical structure and transaction network position.

複合型誘電性エラストマーアクチュエータの開発及び特性評価

Dielectric elastomers, as a type of electroactive polymers, have shown great potential for applications. In this study, electromechanical properties of nylon fibers and styrene bars reinforced dielectric elastomer actuators (DEA) are evaluated. As a result the curvature of the styrene bars reinforced DEA is larger than that of the nylon fiber reinforced DEA at a given voltage. Moreover, the time dependence and cyclic dependence of the styrene bars reinforced DEA are investigated and discussed.

Structural Mechanism for the Regulation of HCN Ion Channels by the Accessory Protein TRIP8b

Hyperpolarization-activated cyclic nucleotide-gated (HCN) ion channels underlie the cationic Ih current present in many neurons. The direct binding of cyclic AMP to HCN channels increases the rate and extent of channel opening and results in a depolarizing shift in the voltage dependence of activation. TRIP8b is an accessory protein that regulates the cell surface expression and dendritic localization of HCN channels and reduces the cyclic nucleotide dependence of these channels. Here, we use electron paramagnetic resonance (EPR) to show that TRIP8b binds to the apo state of the cyclic nucleotide binding domain (CNBD) of HCN2 channels without changing the overall domain structure. With EPR and nuclear magnetic resonance, we locate TRIP8b relative to the HCN channel and identify the binding interface on the CNBD. These data provide a structural framework for understanding how TRIP8b regulates the cyclic nucleotide dependence of HCN channels.