Loop Type Research Articles

Classification and unified phenomenological modeling of complex uniaxial rate-independent hysteretic responses

The number and nature of hysteretic responses typically exhibited by mechanical systems and materials are so huge that their modeling and identification are usually carried out on an ad-hoc basis. Thus, with the aim of proposing a unified approach to the modeling of rate-independent hysteretic behavior, we first perform a detailed classification of complex generalized force–displacement hysteresis loops, ranging from the asymmetric, pinched, S-shaped, flag-shaped ones to those obtained by their arbitrary combination, since they typically span the vast majority of loops obtained experimentally. Subsequently, we formulate a novel rate-independent hysteretic model, having an exponential nature, that offers a series of advantages over other hysteretic models available in the literature. Indeed, it adopts closed form expressions for evaluating the output variable, with important benefits in terms of computational efficiency and implementation ease, and it allows for an uncoupled modeling of the generic loading and unloading phases by means of two different sets of eight parameters. In addition, it requires the use of a simple identification procedure thanks to the clear theoretical and/or experimental interpretation of the adopted parameters. The accuracy of the proposed model is experimentally and numerically validated and its computational efficiency is demonstrated. In particular, the experimental validation is carried out by reproducing four different types of complex experimental hysteresis loops retrieved from the literature, whereas the numerical validation is performed by running some nonlinear time history analyses on a single degree of freedom mechanical system and comparing the results with those obtained by using a modified version of the celebrated Graesser–Cozzarelli model.

The "Deep Subarcuate Fossa" sign and three types of anomalous subarcuate loops encountered during vestibular schwannoma removal.

An anomalous subarcuate loop (SL) of the anteroinferior cerebellar artery (AICA) is a rare anatomic variation, which increases the complexity and risk of vestibular schwannoma (VS) removal. However, preoperative diagnosis of this anomaly remains difficult. The aim of this study was to report three types of anomalous SLs encountered during VS removal and to describe the "Deep Subarcuate Fossa (SF)" sign and its significance in the diagnosis and treatment of an osseous-penetrating SL. We prospectively observed 963 patients with newly/recently diagnosed VS who underwent surgical treatment performed by the senior author (P.Z.) from 2012 to 2021 and identified 16 patients with an anomalous SL. The SF was retrospectively measured on preoperative thin-slice temporal bone computed tomography in 963 patients. Three types of anomalous SLs were encountered during VS removal: the apex of the SL was embedded in the dorsal tumor capsule (type I, 1 case), the dura (type II, 8 cases), or the dura and bone (type III, 7 cases) surrounding the SF. The depth of the SF in 7 patients with a type III anomalous SL ranged from 2.3 to 7.0mm (3.56 ± 1.56mm), which was significantly larger than that in 845 patients without an osseous-penetrating SL (1.23 ± 0.43mm) (p = 0.008). When the depth of the SF exceeded 2mm, the sensitivity and precision of the diagnosis of a type III anomalous SL were 100% (7/7) and 31.8% (7/22), respectively. Three types of anomalous SLs may be encountered during VS removal, and AICA displacement is recommended before tumor removal. The "Deep SF" sign may indicate the existence of a type III anomalous SL and it can predict the depth of the AICA in the bone and guide the drilling of the bone around the vessel loop.

Does Citizen Engagement With Government Social Media Accounts Differ During the Different Stages of Public Health Crises? An Empirical Examination of the COVID-19 Pandemic.

BackgroundThe COVID-19 pandemic has created one of the greatest challenges to humankind, developing long-lasting socio-economic impacts on our health and wellbeing, employment, and global economy. Citizen engagement with government social media accounts has proven crucial for the effective communication and management of public health crisis. Although much research has explored the societal impact of the pandemic, extant literature has failed to create a systematic and dynamic model that examines the formation mechanism of citizen engagement with government social media accounts at the different stages of the COVID-19 pandemic. This study fills this gap by employing the Heuristic-Systematic Model and investigating the effects of the heuristic clues including social media capital, information richness, language features, dialogic loop, and the systematic clue including content types, on citizen engagement with government social media across three different stages of the pandemic, employing the moderating role of emotional valence.MethodsThe proposed model is validated by scraping 16,710 posts from 22 provincial and municipal government micro-blog accounts in the Hubei province, China.ResultsResults show that the positive effects of social media capital on citizen engagement were observed at all stages. However, the effects of information richness, language features, dialogic loop, and content types, and the moderating effect of emotional valence, varied across the different pandemic development stages.ConclusionsThe findings provide suggestions for the further effective use of government social media, and better cope with crises. Government agencies should pay attention to the content and form of information shared, using technical means to analyze the information needs of citizens at different stages of public health emergencies, understanding the content most concerned by citizens, and formulating the content type of posts.

Patient experiences with patient-reported outcome measures in metastatic breast cancer trials: qualitative interviews

BackgroundPatient-reported outcome (PRO) measures are critical for assessing treatment benefit of anticancer treatments. Although PRO measures have been developed with the intention of capturing patient-centric concepts, a gap exists in understanding the patient experience with these tools. We characterized the experience of patients with metastatic breast cancer (mBC) with PRO measures in an oncology clinical trial setting to determine the importance, relevance, barriers, and facilitators for PRO completion.MethodsThe multicenter, qualitative design included semistructured interviews with 18 women with mBC who completed PRO measures in a clinical trial setting within 1 year of screening. Interviews began with concept elicitation to understand symptom characterization, decision to participate in a clinical trial, pre-trial expectations, and thoughts on study-related questionnaires. Cognitive debriefing was conducted to determine if items in a commonly used PRO instrument were relevant to the patient experience. Qualitative data were analyzed using a constant comparative approach.ResultsParticipants described the need for detailed explanation of PRO measures at study start, including information about how the PRO data will likely be used to support drug development. Respondents who felt connected to clinical trial research were more likely to feel as if the measures adequately captured their experiences. Items that were deemed irrelevant or out of date to the patient experience may cause a respondent to feel marginalized and adds to the overall burden of PRO measure completion. Mode of PRO measure administration (electronic/paper) was important to some, but placement of the instrument completion within a study visit appeared to influence respondent willingness to fully engage with the measures. A lack of any type of feedback loop to allow respondents to learn from the captured PRO data was noted as important but missing from the patient experience.ConclusionsPRO measures need to include content that is relevant to the patient experience over the course of the clinical trial period to be considered meaningful to respondents, and administration techniques also impact engagement. Robust communication strategies that socialize the intent, use, and results of PRO data may enrich the patient experience and support greater adherence to PRO completion in future studies.

Vascular loop in the cerebellopontine angle: Clinical-radiological correlation

BackgroundThe brainstem, situated in the posterior fossa, connects the brain to the spinal cord. Owing to its location, the nerves of the brainstem are closely related with vascular structures. ObjectivesTo correlate the finding of vascular loops in the cerebellopontine angle on imaging with symptoms indicative of vestibulocochlear involvement. Materials and methodsThis retrospective descriptive study included all patients evaluated between 2011 and 2017 with findings suggestive of vascular loops in the cerebellopontine angle for whom the clinical history and imaging studies were available. ResultsA total of 102 patients (63 women and 39 men) had vestibulocochlear involvement. The most common clinical indication was dizziness (41.18%). A unilateral vascular loop was found in 43 patients (right: 21.57%, left: 20.59%) and bilateral loops were found in 59 (57.84%) patients. The most common type of vascular loop was type II (right: 69.14%; left: 58.75%). The most common origin of vascular loops was the anterior inferior cerebellar artery (right: 66.67%, left: 65.00%). No associations were observed between vascular loops and sensorineural hearing, nystagmus, or vertigo. There was an association with tinnitus. Conclusions and significanceThe presence of vascular loops is not associated with most auditory symptoms. Nevertheless, all findings on imaging studies must be reported. The interpretation of the findings of imaging studies must be correlated with the clinical symptoms after other more common causes that can explain the symptoms have been ruled out.

Geometric Design of Planar Scissor Linkages with Hybrid Loop Assemblies

Due to their expansion capabilities and the simplicity of their design, scissor linkages have been used in both architecture and engineering for various applications, such as expandable roofs and shelters, movable bridges, furniture, and as parts of mechanisms. The two main design methods used for scissor linkages are the unit-based method and the loop-based method. While the unit-based method is based on serial multiplication of the scissor units, the loop-based method is based on aligning predefined loop types onto the desired curve. When the input parameter is the desired curvature for the finally deployed configuration of the linkage, the loop-based method is easier and more convenient for defining the scissor units to create the whole linkage geometry. Most of the existing studies on the loop-based method deal with identical or arbitrary loops. Hybrid loop assemblies have not yet been studied, although they may offer different geometric alternatives. This work aimed to fill this gap in the literature and present a geometric design approach for scissor linkages composed of hybrid loop assemblies using frieze patterns. First, the basic terminology, such as loop types, loop assemblies, and frieze patterns, is introduced. Then, we discuss scissor linkages using hybrid loops, generated using a predefined rectilinear geometry in which frieze groups are used to provide diverse variations. The kinematic definitions of the represented linkages are then explained. To reveal the potential applications of the scissor linkages composed of hybrid loops, a case study was conducted in which the proposed linkages were used as a canopy structure. After discussing the potential for using hybrid loops, and their deployment, we present the concluding remarks and make suggestions for future research.

Radiation-induced segregation on dislocation loops in austenitic Fe-Cr-Ni alloys

Radiation-induced segregation of alloying elements to crystallographic defects is commonly observed in irradiated austenitic stainless steels. The interaction between solutes and radiation-induced defects changes the physical distribution of solutes and thus affects the formation and growth of defects. The change of the microstructure consequently affects the mechanical properties of the material. A qualitative and quantitative understanding of the interaction between solutes and defects is desirable to better predict the service lifetime of nuclear materials. We used atom probe tomography to measure the distribution of solutes at dislocation loops in 304L stainless steel, irradiated with 2 MeV protons up to 1.5 displacements per atom at 373 and 633 K. No segregation at dislocation loops was found in samples irradiated at 373 K, whereas Ni and Si enrichment and Cr depletion were detected at dislocation loops irradiated at 633 K. The experimentally observed perfect and faulted dislocation loops in vacancy and interstitial types were reproduced by molecular dynamics (MD). A hybrid MD/Monte Carlo method was used to predict the redistribution of alloying atoms at all possible types of dislocation loops in face-centered cubic Fe-Cr-Ni alloys at the same irradiated temperatures (373 and 633 K). The simulations show that, at both temperatures, Cr clusters were formed and distributed randomly, and Ni atoms enriched or depleted at interstitial or vacancy dislocation loops, respectively. The change of solute concentration reaches the highest at the edge of the loop. Ni profiles exhibit characteristic behavior in terms of the stress field of the loops: tension inside of vacancy loops showing depletion of Ni atoms compared with compression inside of interstitial loops showing enrichment of Ni atoms. In addition, the stress field is reduced after solute redistribution. The absence of alloying segregation observed in experiments at a lower temperature (373 K) is explained by a rate theory model: Low-temperature irradiation requires significantly longer irradiation time to see the same amount of segregation as at high temperatures because of the extremely low diffusion of vacancies at low temperatures.

Autistic twisted loops

ABSTRACT The paper describes a deceptive kind of autistic encapsulation, charact-erised by pseudo-internal space and distortions in the normal development of psychophysical space. It introduces the metaphor of loops as spatial-temporal organisations that illuminate three aspects of autistic encapsulation, two of which were first described by Frances Tustin. Three types of loops – simple, twisted and double-twisted – are explored. The paper delineates the double-twisted loop as an additional and more complex manifestation, typical to post-autistic organisation. Here, symbolic thinking and communication function as a disguise, obscuring the child’s trajectory on an infinite continuum that folds around itself, thus denying the potential for separateness and preventing the accumulative realisation of mental space. Using two clinical vignettes, the author shows how such a presentation leaves the therapist in danger of being tempted by the child’s pseudo-internal world, while remaining dissociated from their developmental needs.

Relative population of 1/2 and interstitial loops in alpha-Fe under irradiation: Effects of C15 cluster stability and loop one-dimensional movement

The relative stability of 1/2<111> and <100> dislocation loops, originating from anisotropic elasticity of alpha-Fe, was extensively exploited to explain experimentally observed variation in the relative population of the two loop types under varying irradiation temperatures. In this study, using cluster dynamics simulations taking into account the coevolution of C15 Laves phase structure (cluster) and loop reaction caused by defect one-dimensional (1-d) movement, we reveal new mechanisms that may underpin the variations in loop population of different Burgers vectors. We identify that C15 clusters have twofold roles in mediating loop evolution: (1) acting as buffers of self-interstitial atoms, (2) initiating loop nuclei via their collapses. The latter plays a critical role in nucleation of <100> loops and subsequently affects loop evolution of both types. We show that the loop relative population undergoes further re-arrangement via a transfer reaction driven by loop long-range diffusion. Our findings essentially demonstrate that, apart from the loop stability, the relative population of two loop types is governed by at least two other factors: C15 cluster stability and loop 1-d movement.

Impact of small defects and dislocation loops on phonon scattering and thermal transport in [formula omitted

Radiation damage can significantly degrade the thermal conductivity of ThO2 due to enhanced phonon-defect scattering. To quantify the effect of radiation-induced defects on thermal transport, we employ non-equilibrium molecular dynamics simulations to estimate the thermal conductivity in the presence of various types of defects. For each defect species, the phonon-defect scattering cross-section is extracted based on analytical models. In addition, the impact from two types of experimentally-observed dislocation loops (perfect and faulted) on thermal transport is examined with respect to the loop size and orientation. Notably, simulation cell size effects are analytically and quantitatively addressed via a phonon-mean-free-path-resolved analysis. It can be concluded that, for a given total number of defect sites per unit volume, agglomerating defects into larger clusters improves thermal conductivity compared to isolated defects. Importantly, this work provides quantitative information towards the defect-specific thermal conductivity, and phonon-defect scattering cross-sections, which can serve as inputs to large-scale transport models to quantify the evolution of overall thermal conductivity of ThO2 under irradiation.

Dislocation loop evolution in Kr‐irradiated ThO2

AbstractThe early stage of microstructural evolution of ThO2, under krypton irradiation at 600, 800, and 1000°C, was investigated using in situ transmission electron microscopy (TEM). Dislocation loops grew faster, whereas their number density decreased with increasing irradiation temperature. Loop density was found to decrease with ion dose. Interstitial dislocation loops, including Frank loops with Burgers vector of a/3〈111〉 and perfect loops with Burgers vector of a/2〈110〉, were determined by traditional TEM and atomic resolution–scanning TEM techniques. Atomistic and mesoscale level modeling are performed to interpret experimental observations. The migration energy barriers of defects in ThO2 were calculated using density‐functional theory. The energetics of different dislocation loop types were studied using molecular dynamics simulations. Loop density and diameter were analyzed using a kinetic rate theory model that considers stoichiometric loop evolution. This analysis reveals that loop growth is governed by the mobility of cation interstitials, whereas loop nucleation is determined by the mobility of anion defects. Lastly, a rate theory model was used to extract the diffusion coefficients of thorium interstitials, oxygen interstitials, and vacancies.

A methodical survey of mathematical model-based control techniques based on open and closed loop control approach for diabetes management

Disturbance of blood sugar level is controlled through well-known biomechanical feedback loops: high levels of glucose in blood facilitate to release insulin from the pancreas which accelerates the absorption rate of cellular glucose. Low glucose levels encourage to release pancreatic glucagon which induces glycogen breakdown to glucose in the liver. These bio-control systems do not function properly in diabetic patients. Though the control of disease seems intuitively easy, in real life, due to many differences in structure by diet and fasting, exercise, medications, patient’s profile and other stressors, it is not that easy. The mathematical models of the glucose-insulin regulatory system follow the patient’s physiological conditions which make it difficult to identify and estimate all the model parameters. In this paper, we have given a systematic literature review on mathematical models of the diabetic patients, and various kinds of disease control techniques through the development of open and closed loop insulin deliver command system and optimization of exogenous insulin rate. It demonstrates the open and closed loop type model-based control strategies underlying the assumptions of the concerned models. The combination of mathematical model with control strategies such as genetic algorithm (GA), neural network (NN), sliding mode controller (SMC), model predictive controller (MPC), and fuzzy logic control (FLC) has been considered, which provides an overview of this area, highlighting the control profile over the diabetic model with promising clinical results, outlining key challenges, and identifying needs for the future research. Also, the significance of these control algorithms has been discussed in the presence of the noises, the controller’s robustness and various other disturbances. It provides substantial information on diabetes management through various control techniques.

System dynamics tool for entropy-based risk control on sleeve grouting in prefabricated buildings

PurposeThe production of sleeve grouting in prefabricated construction is routinely plagued by a variety of factors, and lack of mass data and complex environmental conditions over time make problems inevitable. Thus, a dynamic risk control system is a valuable support for the successful completion of the sleeve grouting process. This study aims to develop an entropy-based sleeve grouting risk dynamic control system.Design/methodology/approachFirst, static risk assessment was conducted through the structured interview survey using the entropy weight method, followed by a dynamic risk control technique, where indicators were simulated through system dynamics containing causal loop diagrams and stock-and-flow diagrams.FindingsFinally, three types of risk control models, namely, “tortuous type”, “stable type” and “peak loop type”, were developed in the entropy-based sleeve grouting risk dynamic control system and simulated using system dynamics in a real case.Originality/valueCompared to traditional sleeve grouting risk management, the developed system enabled dynamic control over time.

REKONFIGURASI PENYULANG KINTAMANI UNTUK MENURUNKAN.RUGI-RUGI.DAYA.DAN JATUH TEGANGAN PADA WILAYAH KERJA ULP BANGLI

The Kintamani supplay is uone of the feedersl in the PT PLN (Persero) UP3 East Bali Work Areawhich is the responsibility of ULP Bangli. This feeder uses a loop type configuration that servesconsumers in the Penelokan, Songan, Kintamani, Writing, Catur and Sukawana areas. This feederhas a channel length of 237,886 kms with a total distribution substation of 183 transformer units andthe peak load of this feeder reaches 3,160 kW. This condition causes a voltage drop of 7.68% andpower losses of 7.5%. The reconfiguration of this feeder is done by cutting the network which istransferred to Nandini's feeder. Reconfiguration by cutting the network shows an improvement in thevoltage of the Kintamani feeder which initially dropped from 7.68% to 3.27% and decreased powerlosses from 7.5% to 4.81%. Improvements in voltage and power losses that occur in this feederchange the value of the voltage drop and power losses on the Nandini feeder, which has an increasein the percentage of voltage drop from (-)1.44% to 1.27% and losses the initial power of 0.5% to2.10%. With this the Kintamani feeder is right for reconfiguration with the Nandini feeder. Thus, for theKintamani feeder and the Nandini feeder, it is in accordance with the 2017-2022 Distribution SystemMaster Plan Manual, where the maximum allowable voltage drop is a maximum of 19kV and amaximum power loss of 5%.

Korelacje pomiędzy wzorami listewek skórnych na opuszkach palców rąk

Attention was focused on correlations between four basic types of dermatoglyphic patterns on finger bulbs of 3,100 men. The dominating associations were found in homologous and neighboring fingers. The most strongly correlated group of patterns proved to be whirls (W) which moreover constituted the only group to reveal no positive relations with the other types of patterns, namely arches (A), ulnar loops (Lu), and radial loops (Lj.).

Switching Diagram of Core-Shell FePt/Fe Nanocomposites for Bit Patterned Media.

In the current work, a core-shell type exchange coupled composite structure was constructed by micromagnetic simulation with a phase FePt core and an iron shell. Four types of switching loops with magnetic domain structure evolution were demonstrated. Based on the simulation results, a switching type diagram was constructed, which displays various hysteresis loops as a function of core radius and shell thickness. Furthermore, the effects of switching type and composite structure on the coercivity and remanent magnetization were predicted and discussed. This finding indicates that core-shell type FePt/Fe composite structure film has a large advantage in designing exchange-coupled bit patterned media to realize high-density storage devices at the nanoscale.

Zingerone Modulates Neuronal Voltage-Gated Na+ and L-Type Ca2+ Currents.

Zingerone (ZO), a nontoxic methoxyphenol, has been demonstrated to exert various important biological effects. However, its action on varying types of ionic currents and how they concert in neuronal cells remain incompletely understood. With the aid of patch clamp technology, we investigated the effects of ZO on the amplitude, gating, and hysteresis of plasmalemmal ionic currents from both pituitary tumor (GH3) cells and hippocampal (mHippoE-14) neurons. The exposure of the GH3 cells to ZO differentially diminished the peak and late components of the INa. Using a double ramp pulse, the amplitude of the INa(P) was measured, and the appearance of a hysteresis loop was observed. Moreover, ZO reversed the tefluthrin-mediated augmentation of the hysteretic strength of the INa(P) and led to a reduction in the ICa,L. As a double ramp pulse was applied, two types of voltage-dependent hysteresis loops were identified in the ICa,L, and the replacement with BaCl2-attenuated hysteresis of the ICa,L enhanced the ICa,L amplitude along with the current amplitude (i.e., the IBa). The hysteretic magnitude of the ICa,L activated by the double pulse was attenuated by ZO. The peak and late INa in the hippocampal mHippoE-14 neurons was also differentially inhibited by ZO. In addition to acting on the production of reactive oxygen species, ZO produced effects on multiple ionic currents demonstrated herein that, considered together, may significantly impact the functional activities of neuronal cells.

Radiological evaluation of maxillary artery and descending palatine artery in the pterygopalatine fossa by 3D rotational angiography.

The aim of this study is to evaluate the branching patterns and topographical features of the third part of the maxillary artery (t-MA) and descending palatine artery (DPA) by 3-Dimensional Rotational Angiography (3DRA) images and to define the radiological classification of their variations, based upon the previous cadaveric studies and a review of the literature. This study was conducted from May 2020 through June 2021. All consecutive adult patients who were examined with 3D-RA were enrolled in the study. The morphological evaluations and measurements of t-MA, DPA and their branches were made on maximum intensity projection images with 10-20mm slice thickness. Eighty-five hemifaces, including 58 females and 45 right sides, were evaluated. The diameter of the t-MA was measured as 1.73 ± 0.30mm. The most common pattern of the t-MA according to its course was loop type (63/85, 74.1%) and according to branching pattern was Type Ib (29/85, 34.1%). The mean diameter of DPA was 1.19 ± 0.20mm. The DPA presented as a single trunk in 11/85 cases. Type II, which was defined as one lesser palatine artery originating from distal-DPA, was the most common morphological variation (51.8%). 3DRA imaging provides valuable information for vascular anatomical studies. The most common morphological variation related to t-MA, DPA is the distal branching pattern.

Association of Dermatoglyphic Patterns with DMFT Score, Salivary pH and Plaque Index Score: An In-Vivo Study

Background: Dental caries, although of infectious origin along with its multiple predisposing factors, may have a genetic predisposition. This study was executed to evaluate the association of dermatoglyphics as a genetic predictor of the susceptibility of participants to acquire dental caries considering environmental factors such as salivary pH, Decayed, Missing and Filled Permanent (DMFT) Score and Plaque Index Score. Methods: 531 student volunteers of a dental college were included in the study. Thumbprint patterns of the thumbs of their respective dominant hands were analyzed. DMFT Index, Plaque Index Score and Salivary pH for each subject was recorded. Statistical analysis was executed using nonparametric chi-square tests, correlation coefficients and measures of central tendencies. Results: The predominant thumbprint pattern seen was loop type followed by whorl and arch type with 52%, 31% and 17% of occurrence and a salivary pH of 7, 5 and 6 respectively. The Chi-Square tests concluded that whorl type of thumbprints show association with increased DMFT score. Mean and median plaque index score was considerably higher in the individuals with a whorl type of thumbprint. Conclusion: There was distinct association between pattern of thumbprints and prevalence of dental caries. Whorl type thumbprint could prove itself as a genetic predictor towards increased caries incidence.

Making a difference in the real world. User-centred impact evaluation of an eight-country, community-based early childhood programme

This paper presents a unique approach to the Impact Evaluation of a project that focused on low-threshold intergenerational play-based interactions in order to support young children from marginalised communities in eight European countries. The approach builds upon the work of Fetterman’s Empowerment Evaluation and Patton’s Utilization Focused Evaluation and brings them together to form an adapted model of evaluation. We outline in this paper how these two well developed methods of evaluation have been applied to a real world context, that is, the impact evaluation of a complex international project. Our approach highlights the complexities of differing contexts and allows for surprising and unintended consequences to emerge. It results, through double loop learning, a type of feedback loop with the internal stakeholders and implementers that is useful to the project coordination team, with a view to further upscaling of the initiative. Recommendations for policy at local, national and European Union levels were provided to the project and potential external users. However, the predominant feedback was provided at two crucial points along the way; during a stakeholder mapping exercise and during the further development of monitoring data tools.