Reciprocal System Research Articles

Asymmetric Directional Control of Thermal Emission.

Control over the directionality of thermal emission plays a fundamental role in efficient heat transport. Although nanophotonic technologies have demonstrated the capability for angular-selective thermal emission, achieving asymmetric directional thermal emission in reciprocal systems with energy directed to a single output angle remains challenging due to symmetric band dispersion. In this work, wepresent a general strategy for achieving asymmetric directional thermal emission in reciprocal systems. With periodic perturbation and broken mirror symmetry, metasurfaces behave as resonant metagratings whose resonances can be diffracted to symmetric output angles with distinct efficiency, allowing for high emissivity towards a single direction. The asymmetric directional thermal emitter is experimentally demonstrated at mid-infrared wavelengths with high emissivity (ε = 0.61) at the observation angle of +30°, and low emissivity (ε<0.3) at other angles. This work highlights the potential for manipulating the directionality of thermal emission, which holds promise for developing ultrathin customized thermal sources and impacts on various thermal-engineering applications. This article is protected by copyright. All rights reserved.

Asymmetric elastic wave scattering in elastic plates

Reciprocity is a fundamental principle that can be used to understand a wide range of wave phenomena. In reciprocal systems, the exchange of source and receiver between two points yields the same displacement at the receiver if the applied force at the source is the same for both configurations. The reciprocity principle enforces restrictions on the scattering matrix in an acoustic or elastic system, but these relationships are not obvious when multiple modes are present, particularly when modes are coupled due to the presence of asymmetric scatterers. In this talk, we apply the reciprocity principle in a simplified two-dimensional waveguide case to prove symmetry of the scattering matrix in passive systems with and without loss and establish requirements for asymmetric scattering. The requirements enforced by reciprocity and energy conservation are then generalized to Lamb modes of arbitrary order. Applications to acoustic and elastic metamaterial design and ultrasonic nondestructive evaluation are discussed. [Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA-0003525.]

Time reversal acoustic focusing in a reverberant room: Elongating a focus, and the effect of head-scattering

Time reversal acoustics (TRA) has tremendous potential for focusing, or sound concentration, in reverberant architectural environments. While TRA provides an inherently simple means of achieving a high degree of spatiotemporal focusing, its appropriateness for listening applications in the built environment is challenged by the need to accommodate a person within a sufficiently large focal area. At its simplest, a reciprocal time reversal focusing system for audible range sound will produce a focus with a spatial spread corresponding to one-eighth of the wavelength, which is inconveniently small for speech frequencies. However, an elongated focus is introduced by deploying a directional impulse response, which can be created with a directional microphone, or synthesized by time-delay-mixing of multiple omnidirectional impulse responses. This paper reports on results of physical experiments conducted in a reverberant room, complemented by finite-different time-domain simulations in which the effect of introducing a head-sized scatterer was investigated.

Experimental study and thermochemical assessment of the reciprocal system Li+, K+//Cl−, CO32−

In this work a new thermodynamic dataset of the reciprocal system Li+, K+//Cl−, CO32− was generated by using Calphad method with FactSage. After collecting and analyzing the available thermodynamic data in the literature, experiments were designed to improve the comprehensiveness of the new database. Specifically, Differential Thermal Analysis (DTA) was used (1) to confirm the eutectic temperature of the K2CO3–KCl system, (2) to check the solid solubility in the K2CO3–Li2CO3 system and (3) to measure the phase equilibria of the diagonal sections (i.e. Li2CO3–(KCl)2 and K2CO3–(LiCl)2) in the reciprocal system. In addition, the heat capacity of the intermediate compound LiKCO3 was measured by three types of Differential Scanning Calorimetry (DSC) and its phase transformation was studied by High temperature X-ray Diffractometry (HTXRD). Based on the literature data and the present experimental results, the thermodynamic data on pure LiCl, all sub-binary systems and the reciprocal system were reassessed in the new database, which can be used to calculate and predict the thermodynamic properties of the salt mixtures in the reciprocal system Li+, K+//Cl−, CO32− more precisely and reliably.

SURFACES OF CRYSTALLIZATION AND PHASE RELATIONS IN THE 6Ag2Se+Ag8SiTe66Ag2Te+Ag8SiSe6 RECIPROCAL SYSTEM

The paper presents the results of a study of phase equilibria in the 6Ag2Se+Ag8SiTe6 6Ag2Te+Ag8SiSe6 reciprocal system by DTA and XRD methods. The projection of the liquidus surface, isothermal sections at 300, 500, 1150 K, and some polythermal sections of the phase diagram are constructed. It is shown that the system is reversible-reciprocal. It is characterized by the formation of continuous high-temperature solid solutions along the Ag8SiSe6-Ag8SiTe6 () and Ag2Se-Ag2Te () boundary systems. It has been established that the liquidus surface of the reciprocal system consists of two fields of primary crystallization - and -phases. These surfaces are delimited by a eutectic curve with monovariant equilibrium L+. In the subsolidus part of the system, a complex interaction is observed associated with the polymorphism of the initial compounds and phases based on them

The Effect of Using Different Kinematics Single File Systems with Coronal Preflaring Instruments on Postoperative Pain with Symptomatic Irreversible Pulpitis: A Randomized Clinical Trial

IntroductionThe aim of this study was to investigate the effect of using coronal preflaring file (One Flare; OF) with rotational (One Curve; OC) and reciprocal (WaveOne Gold; WOG) single file systems on postoperative pain in mandibular premolar teeth with symptomatic irreversible pulpitis. MethodsEighty patients were included in this prospective, superiority, parallel, and randomized controlled clinical trial. The patients were randomly divided into four groups (n = 20) based on the use of coronal preflaring and the kinematics of the shaping instrument: WOG (without coronal preflaring), WOG with coronal preflaring (OF), OC (without coronal preflaring), and OC with coronal preflaring (OF). Patients recorded their postoperative pain intensity at 6, 24, 48, and 72 hours using a 10-cm visual analog scale. Friedman and Wilcoxon's tests were used for intragroup comparisons, and Kruskal–Wallis test was used for intergroup comparisons. The post hoc analysis was performed using Dunn's test. The Chi-square test was used to compare gender and tooth localization according to the groups, and Kruskal-Wallis test was used to compare age and preoperative pain (P < .05). ResultsAt 6 and 24 hours, WOG and OC with coronal preflaring groups showed statistically significantly lower pain scores than WOG and OC groups without coronal preflaring (P < .05). No significant difference was found between the groups in terms of analgesic medication intake. ConclusionsThe use of coronal preflaring with both rotational and reciprocal single file systems in root canal preparation resulted in less postoperative pain in mandibular premolar teeth diagnosed with symptomatic irreversible pulpitis.

Exploring the Efficacy of 6 Preparation Systems for Achieving Minimal Root Canal Transportation: A Micro-CT Investigation

IntroductionThis study aimed to assess the canal transportation with 6 preparation systems. MethodsSixty curved mesial roots of mandibular molars were scanned, and their root canals (n = 20 per group) were prepared with XP-endo Shaper, BioRace, ProTaper Next, Twisted File Adaptive, Reciproc, or Reciproc Blue systems. After preparation, a new scan was conducted, and transportation was determined by comparing the geometric center of the canal in 13,542 cross-sectional slices. The transport direction frequencies were recorded, and linear transport were compared using a Univariate GLM model and Tukey honestly significant difference tests (α = 5 %). ResultsTransportation was affected by the preparation system and root third (P < .05), with no significant effect observed for the root canal (P > .05). The Twisted File Adaptive had the highest transport (P < .05), and the lowest transports were observed with XP-endo Shaper, ProTaper Next, and BioRace (P < .05). Reciproc Blue and Reciproc showed intermediate results (P < .05). The apical and coronal third exhibited the lowest and highest transportation, respectively (P < .05). A significant interaction was observed between the preparation system and root third (P < .05). In the coronal third, transportation was mostly toward the disto-inside direction, whereas in the middle and apical thirds, transportation was predominantly toward the mesio-outside direction. ConclusionsXP-endo Shaper had the lowest mean linear transportation followed by the ProTaper Next, BioRace, Reciproc Blue, and Reciproc systems. The Twisted File Adaptive system had the worst performance. The direction of transportation was generally toward the inner aspect of the canal at the coronal third and toward the outer aspect of the curve at the middle and apical thirds.

Social Protection Supports and Management of Non-Communicable Diseases in Ghana: A Qualitative Cross-Sectional Perspective of Health Stakeholders

Introduction: Africa faces a double burden of communicable and non-communicable diseases (NCDs). Already, health systems in Africa are overwhelmed with a high burden of communicable diseases with perennial outbreaks of highly infectious diseases. The rise in NCDs comprises an already fragile health system challenging its ability to provide comprehensive care to people living with these diseases. Without responsive social support systems, NCDs will draw more people into catastrophic health financing, worsening health outcomes, and poverty. This study explores how vulnerable people negotiate major disease burdens with the social protection supports available in Ghana. Methods: The study applied a cross-sectional design with a qualitative approach involving healthcare professionals and non-healthcare professionals in 4 regions in Ghana with a total of 32 qualitative interviews analyzed thematically. Results: The main social protection support for the health sector in Ghana is the National Health Insurance Scheme. Other social protection supports such as free maternal healthcare, Livelihood Empowerment Against Poverty, and conventional informal social protection mechanisms do not directly target people afflicted with NCDs. Even though national health insurance covers about 90% of diseases, the quality of care is questionable. Again, the exclusion of diagnostic investigations makes national health insurance a setback to NCD disease management. Also, NCD patients still do out-of-pocket expenses though they have valid national health insurance. Informal social protection supports which used to be effective sometime back are dwindling due to the rising cost of living, gradual breakdown of the African system of reciprocity, and infiltration of Western lifestyles. Conclusion: NCD patients have very limited social protection for the management of their condition. Health insurance which is the only option for many has limited applications. A multidisciplinary body is established by the government to outline more effective ways of offering social protection support for health services, especially chronic conditions such as NCDs which affect a greater proportion of the population.

6Ag2Se + Ag8GeTe6 ↔ 6Ag2Te + Ag8GeSe6 Reciprocal System

Here, we present the results of DTA and XRD studies of phase equilibria in the 6Ag2Se + Ag8GeTe6 ↔ 6Ag2Te + Ag8GeSe6 reciprocal system (system A). A Т–х diagram of the Ag8GeSe6–Ag8GeTe6 boundary system, several inner polythermal sections, isothermal sections at 300 and 1000 K, and the liquidus surface projection were plotted. The Ag8GeSe6–Ag8GeTe6 system is a partially quasi-binary system; it features continuous substitutional solid solutions between Ag8GeTe6 and the high-temperature cubic Ag8GeSe6 phase (the δ phase). Once solid solutions are formed, the polymorphic transition temperature in Ag8GeSe6 decreases, thereby stabilizing the ion-conducting cubic phase in the range of ≥40 mol % Ag8GeTe6 compositions at room temperature and below it. System A is shown to be a reversible reciprocal system; its liquidus surface is comprised of three fields, which relate to the primary crystallization of the solid solutions between the high-temperature Ag2Se and Ag2Te (α phase) phases, IT-Ag2Te-base solid solutions (β phase), and the δ phase. The subsolidus portion of system A features complex interactions related to polymorphism in the terminal compounds and in phases based on them

Construction of Reciprocal Macromodels in the Loewner Matrix Framework

Many of the passive interconnect systems that arise in applications for analysis of power and signal integrity (PI/SI) are reciprocal by nature, and the transfer matrices of such systems are characterized by symmetry constraints. Therefore, it is natural to think in using reciprocal macromodels for the representation of reciprocal systems. Reciprocal macromodels do not only represent in a more faithful way the systems in which they are based upon, but given a reciprocal stable macromodel, it is computationally cheaper to find its passivity violations. This work shows how to construct reciprocal descriptor systems macromodels from black box data using the Loewner matrix (LM) framework, and also, it shows that it is possible to enforce stability and passivity in reciprocal stable macromodels, keeping its size and structure. Various examples of printed circuit board-based high-speed links and power delivery networks described by scattering parameters are used to demonstrate the effectiveness of the proposed approach.

Efficient asymmetrical transmission through a metagrating for underwater acoustic waves

Acoustic asymmetrical transmission is a theoretical and engineering challenge because of the reciprocity of the linear acoustic wave equation. It can be achieved by systems breaking reciprocity or by reciprocal systems relying solely on spatial symmetry breaking. Metagratings are planar structures relying on Bragg's diffraction to reroute wave energy toward a desired direction and are eventually able to achieve asymmetrical transmission when build from an asymmetrical pattern of multiple basic elements. The challenge for water-like media is to combine the geometrical complexity of the structure with good acoustic impedance contrast and practical feasibility. In this work, we build a reciprocal metagrating from brass cylinders arranged according to a numerically optimized pattern and obtain highly efficient asymmetrical transmission for underwater acoustic waves. Around 200 kHz, the structure transmits nearly all incident energy toward a 45° angle when insonified from one side, but act as a near perfect reflector when insonified from the other. The effect relies entirely on the simple phenomena of linear wave diffraction and interference. The generality and efficiency of this device could be of interest for applications in underwater acoustics or medical ultrasounds.

Dynamic indirect reciprocity: When is indirect reciprocity bounded by group membership?

Indirect reciprocity is a strong driver of reputation-based cooperation and previous studies have offered ample evidence as to when and how it guides cooperation towards others. However, the current empirical literature suffers from mixed evidence about the realm of indirect reciprocity; some studies showed that people assume that in-group members, but not out-group members, belong to the same system of indirect reciprocity and they, thus, display reputation-based cooperation only towards in-group members (i.e., bounded indirect reciprocity). Other studies found that people display reputation-based cooperation towards out-group members as well (i.e., unbounded indirect reciprocity). It thus remains unclear when indirect reciprocity is bounded by group membership. We argue that the realm of indirect reciprocity is conditional to the presence of cues of reputational consequences (i.e., consequences of immediate cooperation). We further propose a new perspective, the dynamic indirect reciprocity perspective, which integrates the bounded and unbounded indirect reciprocity perspectives. We conducted a preregistered study (N = 1800) and found partial evidence for the perspective. First, between-condition differences in cooperation were very small and were not in line with the perspective. However, exploratory analyses on psychological underpinnings of intergroup cooperation revealed that a reputation manipulation (i.e., group membership knowledge manipulation) increased cooperation via increased expected cooperation from an immediate partner regardless of their group membership when the cue of reputational consequences was present. Yet, when the immediate partner was an in-group member, this indirect effect was observed when the cue of reputational consequences was absent. Overall, our findings underscore a new general principle of indirect reciprocity: the cue of reputational consequences determines the perceived realm of indirect reciprocity and influences whether or not individuals condition their cooperation to the group membership of immediate interaction partners.

Grasses exploit geometry to achieve improved guard cell dynamics.

Stomata are controllable micropores formed between two adjacent guard cells (GCs) that regulate gas flow across the plant surface.1 Grasses, among the most successful organisms on the planet and the main food crops for humanity, have GCs flanked by specialized lateral subsidiary cells (SCs).2,3,4 SCs improve performance by acting as a local pool of ions and metabolites to drive changes in turgor pressure within the GCs that open/close the stomatal pore.4,5,6,7,8 The 4-celled complex also involves distinctive changes in geometry, having dumbbell-shaped GCs compared with typical kidney-shaped stomata.2,4,9 However, the degree to which this distinctive geometry contributes to improved stomatal performance, and the underlying mechanism, remains unclear. To address this question, we created a finite element method (FEM) model of a grass stomatal complex that successfully captures experimentally observed pore opening/closure. Exploration of the model, including in silico and experimental mutant analyses, supports the importance of a reciprocal pressure system between GCs and SCs for effective stomatal function, with SCs functioning as springs to restrain lateral GC movement. Our results show that SCs are not essential but lead to a more responsive system. In addition, we show that GC wall anisotropy is not required for grass stomatal function (in contrast to kidney-shaped GCs10) but that a relatively thick GC rod region is needed to enhance pore opening. Our results demonstrate that a specific cellular geometry and associated mechanical properties are required for the effective functioning of grass stomata.

Phase Assemblage of the Li+,Na+,K+||F–,Cl–,Br– Five-Component Reciprocal System and Its LiF–KCl–KBr–NaBr–NaCl Stable Pentatope

The phase assemblage of the Li+,Na+,K+||F–,Cl–,Br– five-component reciprocal system was studied for the first time. The phase tree obtained by partition of the phase assemblage into stable elements is linear. It consists of the following stable elements: the LiF–NaF–KF–KBr–KCl pentatope, LiF–NaBr–NaCl–KCl–KBr–NaF hexatope, and NaCl–KCl–KBr–LiBr–LiCl–LiF–NaBr heptatope, linked by the LiF–NaF–KCl–KBr stable tetrahedron and the LiF–KBr–NaBr–NaCl–KCl square pyramid (pentatope). Phase equilibria in the LiF–KCl–KBr–NaBr–NaCl stable pentatope were studied by differential thermal analysis (DTA). Monovariant phase equilibrium L ⇄ LiF + NaClxBr1 – x + KClyBr1 – y occurs in the pentatope, where NaClxBr1 – x and KClyBr1 – y are continuous solid solutions (css) between NaCl and NaBr, KCl and KBr salt pairs, respectively. The composition of the mixture at point Min◻ 591 and the lowest monovariant equilibrium temperature were determined. A 3D computer model was designed as a projection of the phase assemblage on the LiF–KCl–KBr–NaBr–NaCl pentatope in KOMPAS-3D software. The volumes of crystallizing equilibrium phases were outlined.

Wealth inequality in the prehispanic northern US Southwest: from Malthus to Tyche.

Persistent differences in wealth and power among prehispanic Pueblo societies are visible from the late AD 800s through the late 1200s, after which large portions of the northern US Southwest were depopulated. In this paper we measure these differences in wealth using Gini coefficients based on house size, and show that high Ginis (large wealth differences) are positively related to persistence in settlements and inversely related to an annual measure of the size of the unoccupied dry-farming niche. We argue that wealth inequality in this record is due first to processes inherent in village life which have internally different distributions of the most productive maize fields, exacerbated by the dynamics of systems of balanced reciprocity; and second to decreasing ability to escape village life owing to shrinking availability of unoccupied places within the maize dry-farming niche as villages get enmeshed in regional systems of tribute or taxation. We embed this analytical reconstruction in the model of an 'Abrupt imposition of Malthusian equilibrium in a natural-fertility, agrarian society' proposed by Puleston et al. (Puleston C, Tuljapurkar S, Winterhalder B. 2014 PLoS ONE 9, e87541 (doi:10.1371/journal.pone.0087541)), but show that the transition to Malthusian dynamics in this area is not abrupt but extends over centuries This article is part of the theme issue 'Evolutionary ecology of inequality'.

A New Reciprocal System of Burr Type X Densities with Applications in Engineering, Reliability, Economy, and Medicine

Depending on Yousof et al. (2017a), a new one parameter G family of distributions called the reciprocal Burr X-G family is defined and studied. Special member based on the well-known Burr type XII model called the reciprocal Burr X-Burr XII distribution is studied and analyzed. Relevant properties of the new family including ordinary moments, moment of the residual life, moment of the reversed residual life and incomplete moments are derived and some of them are numerically analyzed. Four different applications to real-life data sets are presented to illustrate the applicability and importance of the new family. The new family has proven to be highly capable and flexible in practical applications and statistical modeling of real data.

A Forest of Energy: Settler Colonialism, Knowledge Production, and Sugar Maple Kinship in the Menominee Community

The Menominee have long tapped into and cocreated energy flows within ecosystems, particularly with maple trees. The United States, however, seized nearly all Menominee land, transforming ecosystems into industrial systems, including for maple sugar. Moreover, thermodynamic ideas of energy rendered more-than-human beings into "the ability to do work." Many Menominees, however, have understood "energy" in the more-than-human world from a grounded, relational perspective, guided by an ethical system of reciprocity and an intellectual tradition of interconnectedness. Energy studies has critically examined how societies and cultures are entangled with energy systems, particularly fossil fuels. More research, however, on settler colonialism's impacts on ecological energies from perspectives beyond thermodynamics would greatly strengthen the field. We therefore make three major arguments. First, American settler colonialism is an act of environmental injustice that violently appropriated vast stores of energy, or wealth, embodied in the Menominee's ancestral lands. Second, the Menominee consistently adapted to and resisted colonization by utilizing their ancestral knowledge systems and interspecies ethical frameworks while appropriating dominant science and technology to further their goals. Finally, sugar maple trees provide a material example from which to incorporate an Indigenous energy theory into the study of settler colonialism.

Empowering reciprocal recommender system using contextual bandits and argumentation based explanations

Empowering reciprocal recommender system using contextual bandits and argumentation based explanations

Topological Isomorphism of Liquid–Vapor, Fusibility, and Solubility Diagrams: Analogues of Gibbs–Konovalov and Gibbs–Roozeboom Laws for Solubility Diagrams

The comprehensive topological isomorphism of liquid–vapor, fusibility, and solubility diagrams in the proper sets of variables is proven with the aid of van der Waals equations of the shift in phase equilibrium. Analogues of Gibbs–Konovalov and Gibbs–Roozeboom laws are demonstrated in solubility diagrams of ternary and quaternary systems under crystallization of different types of solid solutions. For the demonstration, the quaternary reciprocal system K+,NH4+||Cl−,Br−−H2O and its ternary subsystems with modeling of the liquid phase within the framework of the classical Pitzer formalism are mainly used. An algorithm for calculating solubility equilibria in these systems is given.

Shaping ability of WaveOne Gold and OneReci by using two apical sizes: a micro-computed tomographic assessment.

OneReci (MicroMega, Besançon, France) is a recently introduced single-file reciprocating system with scarce information revealed on its shaping ability. This study aimed to compare the shaping abilities of OneReci and a well-documented single-file reciprocating system WaveOne Gold (WOG; Dentsply Maillefer, Ballaigues, Switzerland) and evaluate the effect of increased apical enlargement on the preparation quality, using micro-computed tomography (micro-CT). After an initial micro-CT scanning, twenty mesial root canals of mandibular molars were anatomically matched. The canals were assigned to two experimental groups (n=10), using OneReci or WOG in different canals of the same root. The glide paths were created, and root canals were prepared twice, using size 25 and 35 instruments of the systems, respectively. The specimens were scanned with micro-CT after each preparation. The increase in canal volume, amount of dentin removal, unprepared root canal surface, canal transportation, centering ratio and preparation times were assessed. The data were analysed with independent sample t-tests, variance analyses, Friedman and Mann-Whitney U tests. The significance level was set at 5%. Each preparation increased the canal volume and dentin removal while decreasing the unprepared root surface. The difference between the systems became significant after preparation with size 35 instruments (p<0.05). Regarding canal transportation and centering ratio, the difference was insignificant (p>0.05). The first preparation step (glide path + size 25 instrument) was significantly faster in the OneReci group (p<0.05). Preparation with size 25 instruments of the systems appeared to be safe with similar shaping performances. Larger apical preparation promoted significantly higher dentin removal, volume increase, and prepared surface area in WOG.