Full Theoretical Model Research Articles

Floquet Modification of the Bandgaps and Energy Spectrum in Flat-Band Pseudospin-1 Dirac Materials

In this paper, we investigate the so-called electronic dressed states, a unified quasiparticle resulting from the interaction between electrons in a two-dimensional material with an off-resonance optical dressing field. If the frequency of this field is much larger than all characteristic energies in the system, such as the Fermi energy or bandgap(s), the electronic band structure is affected by radiation so that some important properties of the electron dispersions could be modified in a way desirable for practical applications. For example, circularly polarized light can be used to vary the bandgap of Dirac materials: it opens a gap in graphene and other metallic and semimetallic lattices, or it modifies the magnitude of an existing gap. This will either enhance or reduce a gap, depending on its initial value as well as properties of a host material. Here, we consider gapped dice and Lieb lattices as samples, and we put forward a full theoretical model to reveal how these electronic states are deformed by elliptically-polarized irradiation with a focus on the generation and modification of a bandgap.

Stigmatizing ‘evildoers’: how beliefs about evil and public stigma explain criminal justice policy preferences

ABSTRACT Characterizations of offenders as ‘evil’ appear in popular entertainment, political rhetoric, and scholarship and may be rooted in widely endorsed cultural narratives. Integrating psychological and criminological literatures, we argue that endorsement of good-and-evil myths may be associated with criminal justice policy support via stigmatizing attitudes about those who engage in crime. We partially tested these hypotheses in a preliminary study using an online convenience sample (recruited using Amazon MTurk in 2015), then tested the full theoretical model using more comprehensive measures in a survey of American adults conducted via Qualtrics Panel in 2021 (N = 1,162). We found that both belief in evil (i.e. belief in evil forces) and belief in redemptive violence (i.e. belief in a clash between good and evil) were positively associated with punitive policy support, and stigmatizing attitudes partially mediated the effects of both. While belief in redemptive violence was negatively associated with rehabilitative policy support and stigmatizing attitudes mediated that relationship, belief in evil was not associated with support for rehabilitation. We consider the implications of our findings for mitigating the harms of public stigma and punitive criminal justice policy.

Tunable optical chirality of twisted light with graphene

Twisted light carrying orbital angular momentum is inherently chiral. To promote the application of such twisted light in chiral science, it is highly desirable to control its optical chirality in a flexible way. We report here an approach to control the chirality of twisted light by taking advantage of tunable optical properties of graphene. A full vector theoretical model is developed to investigate the chirality of twisted light with Laguerre-Gaussian mode reflected from a graphene-substrate interface. It is revealed that the chirality of twisted light upon reflection is very sensitive to the incident angle. The greater the incident angle, the greater the maximum value of the chirality density. Moreover, the chirality of twisted light can be flexibly tuned by modulating the Fermi energy of the graphene and the substrate refractive index. In addition, the chirality of twisted light can be tuned from positive to negative values by changing the sign of the topological charge. Such tunable optical chirality has potential applications in chiral molecular recognition, chiral structure detection, and chiral micromanipulation.

Stigma by Association: The Unintended Interpersonal Consequences of Associating Oneself with an Abusive Supervisor

Extant abusive supervision research has predominantly studied its prevalence and destructive effects through the lens of victims, potential victims, or third-party observers who witness such mistreatments. In the present research, we examine a neglected group of individuals—employees who are able to develop high-quality relationships and are closely associated with their abusive supervisors. Drawing insights from the stigma-by-association literature, we conceptualize abusive supervision as a unique form of moral stigma that might result in unintended spillover effects. Specifically, we found that observers tend to perceive employees who are closely associated with an abusive supervisor to be less moral and trustworthy for seemingly sharing a similar set of unethical values and beliefs, even though this might not necessarily be true in reality. As a downstream consequence, these employees are subject to unintended interpersonal backlashes (i.e., withdrawal from helping behaviors) imposed by their fellow coworkers. Furthermore, we investigate the moderating role of voluntary motive attribution, revealing that those who were attributed to voluntarily associate themselves with abusive supervisors received the highest levels of interpersonal backlashes. Results from one pilot study, one multiwave survey study (Study 2), and three preregistered experiments (Studies 1, 3, 4) supported our full theoretical model. Our research adds new insights to the abusive supervision literature by introducing a new unintended consequence on a previously overlooked group of employees who are presumed to be shielded from the negative impact of abusive supervision. Funding: This work was supported by the Singapore Ministry of Education [Grant R-317-000-164-115]. Supplemental Material: The e-companion is available at https://doi.org/10.1287/orsc.2023.1678 .

Accurate Measurements of the Thermal Conductivity of n-Docosane, n-Tetracosane, 1,6-Hexanediol, and 1,8-Octanediol in the Solid and Liquid Phases

New measurements of the thermal conductivity of n-docosane, n-tetracosane, 1,6-hexanediol, and 1,8-octanediol, in the solid and liquid phase, are presented. The technique employed is the transient hot-wire technique, based on a full theoretical model. The technique is absolute and is characterized by an uncertainty of 1%. At the 95% confidence level, the standard deviations of the thermal conductivity measurements of n-docosane, are 0.40% for the solid phase (267 K to 308 K), and 0.60% for the liquid phase (330 K to 360 K); of n-tetracosane, 0.60% for the solid phase (265 K to 306 K), and 0.30% for the liquid phase (339 K to 363 K); of 1,6-hexanediol, 0.70% for the solid phase (263 K to 296 K), and 0.40% for the liquid phase (327 K to 351 K); and of 1,8-octanediol 1.1% for the solid phase (265 K to 312 K), and 0.50% for the liquid phase (344 K to 356 K), respectively.

A theoretical framework for acoustically produced luminescence: From thermometry to ultrasound pressure field mapping

Acoustically produced luminescence (APL) can be used for fast and easy mapping of ultrasound pressure fields, allowing quantitative investigation of these fields for a wide range of acoustic frequencies and pressures. APL offers a fast and inexpensive alternative for the conventional point-by-point hydrophone scanning. This can benefit industrial and medical ultrasound applications that experience stringent certification and safety requirements on pressure field characterization. APL was shown to originate from absorption-mediated heating by ultrasound irradiation of a membrane material, which consists of a polymer binder and a luminescent material (or phosphor). This heating induces local thermoluminescence emission, which is proportional to the ultrasound pressure. However, a precise framework describing the physics of the APL process, allowing the retrieval of acoustic field information from the measured light emission has been lacking. Here, we present a full theoretical model of the APL phenomenon, allowing the reconstruction of both the pressure and temperature fields from the measured luminescence. The developed theoretical model is verified using finite-element modeling and experimental validation. We then demonstrate how APL can be used to obtain a 3D reconstruction of an ultrasound pressure field, in a fast and easy way. Finally, the general model demonstrated here can also prove useful for other applications, e.g. in luminescence-based thermometry using persistent phosphors.

Susceptibility to peer influence in adolescents with mild-to-borderline intellectual disability: Investigating links with inhibition, Theory of Mind and negative interpretation bias

ABSTRACT Background This preregistered study compares adolescents with mild-to-borderline intellectual disability (MBID) and typically developing (TD) adolescents on their susceptibility to peer influence. To understand why adolescents with MBID are susceptible to peer influence, links with inhibition, Theory of Mind (ToM) and negative interpretation bias are investigated. Method We assessed 163 adolescents (111 MBID, 52 TD 14–19 years; 63% boys) using experimental tasks and self- and/or teacher-reports. Results Adolescents with MBID and TD adolescents did not differ in their susceptibility to peer influence, inhibition, and negative interpretations. On two ToM instruments, adolescents with MBID performed weaker than TD adolescents. In a structural equation model, tested in the MBID group, inhibition, ToM and negative interpretation bias were not related to susceptibility to peer influence. Conclusions This study revealed new insights by strong methods such as the multimethod approach, a full theoretical model testing relations between all constructs simultaneously, and the large sample.

Social-Psychology of Vaccine Intentions: The Mediating Role of Institutional Trust in the Fight Against Covid-19

This paper examines the social-psychological mechanisms behind how citizens deal with uncertainties stemming from the COVID-19 vaccine developments in societies with prominent social/political cleavages. We argue that existing social/political tensions influence individuals’ trust in institutions that are responsible for coping with crises through a motivated reasoning mechanism, which eventually shapes citizens’ COVID-19 vaccine intentions. Using a nationally representative face-to-face survey conducted in the pre-vaccination period in Turkey, we demonstrate that both self-identifying as a Kurd or feeling close to an opposition party are associated with lower trust in institutions actively dealing with the pandemic, which in turn, results in weaker intentions for getting vaccinated. Testing our full theoretical model reveals that while ethnic and partisan identities do not directly influence vaccine intentions, they exhibit an indirect negative effect via institutional trust impeding the fight against the pandemic. We show that it is difficult to tackle a sudden collective threat that requires public cooperation with health policies if the society is strongly polarized. Our findings offer key policy implications for the vaccination phase of the pandemic, and contribute to the domains of public health, conflict studies and individual judgment and decision-making about social risks.

Incomplete ionization in aluminum-doped 4H-silicon carbide

In this work, we investigate the degree of incomplete ionization of Al doped 4H-SiC. In particular, we perform analysis on a comprehensive list of published measurements of ionization energy, resistivity, and Hall mobility for varying Al concentration. These data are used to construct two separate models with which we calculate the fraction of mobile holes to dopant atoms p/NA. First, we create a physics-based theoretical model which includes the effects of doping-dependent ionization energy, quantum-mechanical spreading of the acceptor density of states, and density of states smearing due to disorder effects. Our second model is derived mainly from experimental Hall and resistivity data, and we use the results of this calculation to verify our results from the theoretical model. We find good agreement between the two approaches which gives confidence to our resulting p/NA calculations. At doping above 1020cm−3, we observe an increase in the p/NA ratio which is likely due to the onset of a parallel impurity conduction mechanism which does not require dopant ionization. We also provide an easily evaluated expression which predicts p/NA at higher temperatures based on our full theoretical model.

Tuneable hopping and nonlinear cross-Kerr interactions in a high-coherence superconducting circuit

Analog quantum simulations offer rich opportunities for exploring complex quantum systems and phenomena through the use of specially engineered, well-controlled quantum systems. A critical element, increasing the scope and flexibility of such experimental platforms, is the ability to access and tune in situ different interaction regimes. Here, we present a superconducting circuit building block of two highly coherent transmons featuring in situ tuneable photon hopping and nonlinear cross-Kerr couplings. The interactions are mediated via a nonlinear coupler, consisting of a large capacitor in parallel with a tuneable superconducting quantum interference device (SQUID). We demonstrate the working principle by experimentally characterising the system in the single-excitation and two-excitation manifolds, and derive a full theoretical model that accurately describes our measurements. Both qubits have high coherence properties, with typical relaxation times in the range of 15 to 40 μs at all bias points of the coupler. Our device could be used as a scalable building block in analog quantum simulators of extended Bose-Hubbard and Heisenberg XXZ models, and may also have applications in quantum computing such as realising fast two-qubit gates and perfect state transfer protocols.

BER in Slow-Light and Fast-Light Regimes of Silicon Photonic Crystal Waveguides: A Comparative Study

In this letter, we present an in-depth comparison between the bit-error ratio (BER) of optical systems containing silicon photonic crystal (Si-PhC) waveguides (Si-PhCWs) operating in the slow- and fast-light regimes. Our analysis of these optical interconnects employs the time domain Karhunen–Loève expansion method for the statistical analysis of the optical signal and relies on a full theoretical model and its linearized form to describe the propagation of noisy optical signals in Si-PhCWs. These models incorporate all key linear and nonlinear optical effects and the mutual interaction between free-carriers and the optical field, as well as the influence of slow-light effects on the optical field and carriers dynamics. Using these tools and employing a 512-b pseudorandom bit sequence, we have studied the dependence of BER on the key system parameters, including group-velocity, input power, and signal-to-noise ratio.

Unpackaging Manager Mistrust in Allowing Telework: Comparing and Integrating Theoretical Perspectives

We developed and tested an integrative model centering on the significance of trust as a basis for managers’ decisions about allowing versus prohibiting their employees to telework. We examined the importance of trust in relation to several other factors managers may consider in making telework decisions including coordination and communication, equity, and a desire to accommodate employees. Study 1 was a policy capturing investigation of 71 respondents intended to document the relative importance and interactions among trust and these other theoretically based factors. Study 2 was a test of the full theoretical model based on the responses of 85 managers who reported on these considerations for the 191 employees about whom they make telework decisions. Results from the two studies were largely consistent. Managers’ assessments of employees’ conscientiousness and trustworthiness were paramount in predicting telework allowance, with the other theoretically based considerations generally failing to attenuate the importance of those personal assessments. Organizations wishing to increase the use of telework (e.g., by implementing manager telework training) must directly address managers’ mistrust as a factor underlying this resistance. Job-related and technological changes may not dampen the effects of mistrust. To our knowledge, this is the most comprehensive and theoretically grounded assessment of the various considerations factoring into managers’ telework decisions.

Modeling and Simulation of Off-Road Vehicle Mobility with Driving Torque Distribution Control on Split Adhesion Conditions

This paper presents a theoretical model for simulation of driving torque distribution control to improve off-road vehicle mobility on split adhesion conditions. The model is constructed and then validated with experimental test rig results. A MATLAB simulink modeling of an electronically controlled device is used to modulate the applied force over multi-plate clutches located between the automotive driven axle shafts and the stationary hub. On driving over split adhesion roads, the control device brakes the spinning axle wheel running over ground low adhesion side and accordingly biases more torque to the other wheel with good adhesion side. This would improve the vehicle off-road mobility and save the power losses on low adhesion wheels. The proposed control model had been validated with experimental results obtained from an experimental tests conducted on a specially designed and built test rig. Consequently, the proposed control system has been embedded within a full car theoretical model to predict the vehicle performance on split adhesion drive conditions. The results showed that the constructed simulink model is suitable for simulating the proposed controlled device for torque distribution after matching the simulation results with experimental test rig results. Moreover, the proposed control model could be implemented to improve the transmitted traction power to the road from a conventional deferential.

Does money matter for infrastructure outcomes? The effects of public infrastructure finance on state infrastructure quality

Given the significant amount of public infrastructure spending and the widely expressed concern about the declining quality of the American public infrastructure system, research about the effectiveness of public infrastructure investment is especially timely and crucial. The study extends public service production theory and public choice theory to the public infrastructure field, and develops a realistic and full theoretical model of public highway production by taking state highway efficiency differences into account. The panel fixed-effects method is used to examine the effects of state highway finance on state highway infrastructure quality. This study finds that state highway maintenance spending plays a crucial role in improving state road and bridge quality. Moreover, highway efficiency elements matter for state highway infrastructure quality.

Behavior of circular thin-walled steel tube confined concrete stub columns

This paper presents a combined numerical and theoretical study on the composite action between steel and concrete of circular steel tube confined concrete (STCC) stub columns under axial compressive loading with a full theoretical elasto-plastic model and finite element (FE) model in comparison with experimental results. Based on continuum mechanics, the elasto-plastic model for STCC stub columns was established and the analysis was realized by a FORTRAN program and the three dimensional FE model was developed using ABAQUS. The steel ratio of the circular STCC columns were defined in range of 0.5% to 2% to analyze the composite action between steel tube and concrete, and make a further study on the advantages of the circular STCC columns. By comparing the results using the elasto-plastic methods with the parametric analysis result of FE model, the appropriate friction coefficient between the steel tube and core concrete was defined as 0.4 to 0.6. Based on ultimate balance theory, the formula of ultimate load capacity applying to the circular STCC stub columns was developed.

Efficient Common-Mode Noise Suppression for Fiber-Optic Interferometric Sensor Using Heterodyne Demodulation

Common-mode noises (CMNs) are frequently encountered in all types of fiber sensor systems. Through involving a reference interferometer, here we report the application of a differential delay heterodyne scheme to suppress CMNs in fiber-optic interferometric sensor systems. The contributions of CMNs are shared by both sensing and reference interferometers and are further suppressed by heterodyne demodulation. For the first time, we develop the full theoretical model describing this method, and experimental results are also presented to confirm the theory. Theoretical analysis shows that the CMN suppression effect (SE, defined as the ratio of the noise floor of the sensing interferometer after and before suppression) is sensitive to several key parameters, including the mean phase difference, the ratio of the visibility, and ac amplitude between the two interferometers. Experimental results show that the proposed method can suppress CMNs by ~24 dB within the frequency range of 20 Hz to 1 kHz. The measured CMN SE agrees well with the theory. The CMN suppression method and the theory reported here can also be extended to other interferometric systems.

Analysis of the electrothermal technique for thermal property characterization of thin fibers

The transient electrothermal technique has been developed to measure the thermal conductivity and thermal diffusivity of electrically conductive or non-conductive nano-to-microscale fibers. In this work, a full theoretical model is developed in detail including the effects of radiation heat loss and non-constant heating as a result of sample temperature rise during measurement, and is compared to the more commonly used reduced model, which neglects these effects. Non-dimensional parameters are derived representing radiation heat loss and non-constant heating to identify the true parameter dependences on these effects. A numerical model is used to perform parametric analyses on the experimental setup providing results that were fitted with the full and reduced models to find thermal conductivity and thermal diffusivity. Additionally, the numerical model was used to investigate nonlinear radiation heat losses and spatially non-uniform heating effects resulting from uneven coating of the conductive layer on electrically non-conductive samples. As a result, these influences are shown to require careful consideration in the application of this technique. A clear linear relationship was found between the non-dimensional parameters and measurement error, which provides a measure for the proper estimation of systematic error induced by these effects. Using the reduced model for data reduction results in measurement percentage error equal to ten times the radiation and non-constant heating dimensionless parameters under the assumption of linear radiation heat losses (small sample temperature rise compared to ambient temperature).

Maternal depression and co‐occurring antisocial behaviour: testing maternal hostility and warmth as mediators of risk for offspring psychopathology

Disruption in the parent-child relationship is a commonly hypothesized risk factor through which maternal depression may increase risk for offspring psychopathology. However, maternal depression is commonly accompanied by other psychopathology, including antisocial behaviour. Few studies have examined the role of co-occurring psychopathology in depressed mothers. Using a longitudinal study of offspring of mothers with recurrent depression, we aimed to test whether maternal warmth/hostility mediated links between maternal depression severity and child outcomes, and how far direct and indirect pathways were robust to controls for co-occurring maternal antisocial behaviour. Mothers with a history of recurrent major depressive disorder and their adolescent offspring (9-17 years at baseline) were assessed three times between 2007 and 2010. Mothers completed questionnaires assessing their own depression severity and antisocial behaviour at Time 1 (T1). The parent-child relationship was assessed using parent-rated questionnaire and interviewer-rated 5-min speech sample at Time 2 (T2). Offspring symptoms of depression and disruptive behaviours were assessed using the Child and Adolescent Psychiatric Assessment at Time 3 (T3). Maternal hostility and warmth, respectively, mediated the association between maternal depression severity and risk for offspring psychopathology. However, the effects were attenuated when maternal antisocial behaviour was included in the analysis. In tests of the full theoretical model, maternal antisocial behaviour predicted both maternal hostility and low warmth, maternal hostility predicted offspring disruptive behaviour disorder symptoms, but not depression, and maternal warmth was not associated with either child outcome. Parenting interventions aimed at reducing hostility may be beneficial for preventing or reducing adolescent disruptive behaviours in offspring of depressed mothers, especially when depressed mothers report co-occurring antisocial behaviour.

Not All Ideologies are Created Equal: Epistemic, Existential, and Relational Needs Predict System-Justifying Attitudes

Whereas most social psychological perspectives assume that needs to manage uncertainty, existential anxiety, and social cohesion should motivate any form of ideological zeal, System Justification Theory predicts that these needs are positively associated with the endorsement of system-justifying beliefs, opinions, and values but negatively associated with the endorsement of system-challenging ideological outcomes. For the first time we test a full theoretical model in which system justification mediates the effects of individual differences in epistemic, existential, and relational needs on attitudes toward public policy issues and social movements. Specifically, we conducted a national survey of 182 Americans and found that, as hypothesized, lower need for cognition, greater death anxiety, and a stronger desire to share reality each contributed significantly and independently to economic system justification, which, in turn, contributed to support for the Tea Party (a movement aimed at restoring America's “traditional values”) and opposition to Occupy Wall Street (a movement seeking to reduce social and economic inequality and minimize corporate influence on government). Economic system justification also mediated the effects of these needs on the endorsement of status quo positions with respect to health care, immigration, global climate change, and the “Ground Zero mosque.” These findings suggest that epistemic, existential, and relational needs lead disproportionately to support for system-justifying, rather than system-challenging, policies and movements.

Membrane Diffusion of Tethered Dimer and Trimer Systems

We have used molecular dynamics simulations to investigate the diffusion of tethered dimer and trimer systems in lipid bilayers. Coarse-grained (CG) models of DPPC dimers were simulated in a DPPC bilayer with the MARTINI model, and single-lipid diffusion constants compared to those obtained for dimmers and trimers at various tether lengths. The ratio of diffusion constants matches well with theoretical predictions of a simple bead model. A full theoretical model of the translational and rotational diffusion of tethered dimers and trimers was developed at the Saffman-Delbruck level, and results were compared to the simple bead model. The ratios of diffusion constants from the theoretical and CG models were then compared to experimental diffusion constants of pleckstrin homology (PH) domains bound to lipids with a PIP3 (phosphatidylinositol (3,4,5)-trisphosphate) head group. Excellent agreement between all systems was found, indicating that the frictional contributions of multiple, coupled but well-separated lipids are additive, analogous to the free-draining limit for isotropic fluids.