Analog Model Research Articles

Was Welling, Ohio (33-Co-2), a Clovis Basecamp or Lithic Workshop? Employing Experimental Models to Interpret Old Collections

Archaeological collections are foundational to the discipline. Yet, researchers who study curated assemblages can face challenges. Here, we show how experimental archaeology can play a vital role in the interpretation of old archaeological collections. The Welling site, in Coshocton County, Ohio, is a multicomponent, stratified site with a substantial Clovis component in its lower levels. Using experimental flaked stone replication, we create an analog model of a “pure” Clovis bifacial debitage assemblage, as might be found at a lithic workshop. We predicted that if the Welling Clovis debitage assemblage was representative of a lithic workshop, then it would be similar to the experimental model. If the debitage assemblage was representative of a base camp, however, then it would be significantly different from the model because Clovis people would have been using, transporting, resharpening, rejuvenating, and recycling the debitage—all activities that would modify a “pure” Clovis bifacial debitage assemblage. Our statistical analyses supported the latter prediction. Overall, our study illustrates how productive the integration of experimental and archaeological data can be, and it emphasizes how important the curation and accessibility of both archaeological and experimental collections are to the discipline.

Classical and quantal aspects of Minkowski's four-momentum in analog gravity

The electrodynamic theory of continuous media is probably the most convenient platform when trying to construct analog gravity theories. Quite naturally, this topic has gained considerable interest. One peculiar but not so very known feature in this context is the unconventional behavior of radiation energy and momentum in cases where superluminal fluid velocities are encountered, what, as known, is a major ingredient in analog gravity theories. These peculiar features are intimately connected with the spacelike character of Minkowski's four-momentum in electrodynamics. Here, we first consider an artificial model in which a Kerr-induced superluminal region is created in the right-hand region ($z>0$) in a left-moving, originally subluminal, fluid. We analyze the behavior of energy density, Poynting vector, and momentum density, and calculate the force on the artificial black hole horizon. Also, we delve into quantal aspects, looking for eventual production of particles associated with the sudden creation of the horizon, finding, however, that no particles are predicted to occur. The present paper continues a previous investigation by the author on the same topic, in Phys. Rev. A {\bf 100}, 032109 (2019). The subject as such is closely related to the famous Abraham-Minkowski problem.

Quantification of principal horizontal stresses inside a tunnel: An application of Fracture induced Electromagnetic Radiation (FEMR) technique in the Darjeeling-Sikkim Himalayas

Characterization of recent stresses, delineation of the locations of active faults/landslide prone slip planes and forecasting earthquakes are some of the emerging applications of the Fracture Induced Electromagnetic Radiation (FEMR) technique. It is believed that such radiation is polarized along the direction of maximum compression and proportional to the maximum applied shear stress. In this paper, we have demonstrated the use of the FEMR technique to calculate the magnitude and directions of principal horizontal stresses inside a tunnel of ~240 m length over a hilly road between Jorethang and Mayong near the village of Miyong in Sikkim, India by taking 11 “cross-sectional” measurements using a portable FEMR recording device called ANGEL-M. Although a reverse stress regime is obvious and established over the Himalayas, the results show a normal stress regime prevailing over this shallow, near-surface region of the tunnel and the direction of maximum shear stress changes along the tunnel length. The results were explained with the aid of a simple clay analogue model where normal reactivation of a thrust plane with changing dips was simulated. With this communication, we hope to encourage scientists and engineers to deploy the FEMR technique which is lesser known but quicker, non-destructive, cheaper, and more accessible than conventional methods in evaluating tunnel safety by calculating shallow stresses locally modified inside a tunnel.

Analogical Model Development Methodology For Mathematical Modeling Of Energy Efficiency Control System

This article presents the methods and principles of developing an analogue model for mathematical modeling of energy efficiency management systems.

Lower self-efficacy and greater depressive symptoms predict greater failure to recover from a single lapse cigarette.

Smoking reexposure after a quit attempt (i.e., lapse) increases relapse risk, but lapse recovery is possible. Using a 6-day analogue model of smoking cessation and lapse, this study tested the effect of a single lapse cigarette on the risk of subsequent smoking. Abstinence self-efficacy (ASE) and depressive symptoms (using the Center for Epidemiological Studies Depression Scale, CES-D) were also examined as hypothesized moderators of lapse recovery. After receiving cessation counseling and achieving 2 days of incentivized abstinence, 54 daily smokers (mean age: 41 years, 61% African American, 63% male) were randomly assigned to smoke 1 cigarette or to a no-lapse control condition. Participants were then offered monetary incentives to abstain for 3 more days and smoking was monitored. Compared to the control condition, participants who experienced a lapse had a 2.5 times greater risk of smoking in the first 24 hours Furthermore, a lapse resulted in much greater risk of subsequent smoking compared to the control condition among individuals with lower postquit ASE scores (p = .044) and greater CES-D scores (p = .040). These findings provide preliminary evidence that a single lapse cigarette after quitting plays a causal role in subsequent smoking and suggest that individuals with lower postquit ASE and greater depressive symptoms are less likely to recover from a lapse. Future research should investigate factors associated with lapse recovery and failure so that effective lapse-responsive strategies can be developed. Laboratory models provide an efficient and controlled method to examine such processes. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

A model of technological enhancement of consumer behavior analysis using the push pull mooring approach in dual-channel apparel retailer

The concept of dual channel supply chain (DCSC) allows retailers to sell their products broadly. Channel collaboration, offline and online, helps companies to survive amid the competition through increasing profits. Nonetheless a review of previous studies in DCSC provided no explicit model addressing consumer behavior to shift channel preference in two directions, offline to online as well as online to offline. This study proposes an analog model to elicit the factors that influence consumer preferences for switching channels from offline to online and from online to offline by using push pull mooring (PPM) approach. Such approach may identify the variables involved in consumer channel switching-intention. The selected object is apparel retailer under dual-channel structure. Furthermore the data is collected by means of questionnaires. Structural equation modelling (SEM) used to identify variables that have a significant effect on consumer switching intention. The results of this study may be used as reference for researchers and apparel retailer managers under DCSC structure to create their operational plans in conducting their business.

Modelling tectonic deformation along the North-Anatolian Fault in the Sea of Marmara

Using analogue techniques, we attempted to model the complex tectonic deformation pattern observed along the North-Anatolian Fault in the Sea of Marmara from morpho-bathymetry and seismic reflection images. In particular this paper focuses on the so-called Cinarcik segment of the fault connecting the eastern Izmit segment, which entirely ruptured during the Mw 7.4, 1999 earthquake, to the western segment of the Central High. The Çınarcık segment, potentially loaded after the Izmit earthquake, is expected to rupture during an earthquake occurring in the near future, possibly the next decades, with a high potential to affect the Istanbul metropolitan area. Our analysis suggests that the development of the observed structures accommodating strike-slip, transtensional and transpressional deformations, could be explained by changes in the geometry of fault segments within a right-lateral strike-slip tectonic regime. Tectonic deformations were reproduced in the analogue model by imposing a small (about 10°) and sharp difference in the relative orientations of the strike-slip segments at the edges of a major releasing bend. In the model slower strain accumulation occurs along the analogue of the Çınarcık segment than along the analogue of the Izmit segment of the fault. This would predict a delay for earthquakes triggered by stress transfer between the Izmit and Çınarcık segments. The model further predicts that most of the deformation in the Çınarcık basin is controlled by the sharp changes in the geometry of the fault itself.

Chiral perturbation theory for GR

We describe a new perturbation theory for General Relativity, with the chiral first-order Einstein-Cartan action as the starting point. Our main result is a new gauge-fixing procedure that eliminates the connection-to-connection propagator. All other known first-order formalisms have this propagator non-zero, which significantly increases the combinatorial complexity of any perturbative calculation. In contrast, in the absence of the connection-to-connection propagator, our formalism leads to an effective description in which only the metric (or tetrad) propagates, there are only cubic and quartic vertices, but some vertex legs are special in that they cannot be connected by the propagator. The new formalism is the gravity analog of the well-known and powerful chiral description of Yang-Mills theory.

Formation Dynamics of Black- and White-Hole Horizons in an Analogue Gravity Model

We investigate the formation dynamics of sonic horizons in a Bose gas confined in a (quasi) one-dimensional trap. This system is one of the most promising realizations of the analogue gravity paradigm and has already been successfully studied experimentally. Taking advantage of the exact solution of the one-dimensional, hard-core, Bose model (Tonks–Girardeau gas), we show that by switching on a step potential, either a sonic, black-hole-like horizon or a black/white hole pair may form, according to the initial velocity of the fluid. Our simulations never suggest the formation of an isolated white-hole horizon, although a stable stationary solution of the dynamical equations with those properties is analytically found. Moreover, we show that the semiclassical dynamics, based on the Gross–Pitaevskii equation, conforms to the exact solution only in the case of fully subsonic flows while a stationary solution exhibiting a supersonic transition is never reached dynamically.

Analytical description of quantum emission in optical analogs to gravity

We consider a moving refractive index perturbation in an optical medium as an optical analogue to waves under the influence of gravity. We describe the dielectric medium by the Lagrangian of the Hopfield model. We supplement the field theory in curved spacetime for this model to solve the scattering problem for all modes and frequencies analytically. Because of dispersion, the kinematic scenario of the field modes may contain optical event horizons for some frequencies. We calculate the spectra of spontaneous emission in the frame co-moving with the perturbation and in the laboratory frame. We also calculate the spectrally-resolved photon number correlations in either frame. The emitted multimode field comes in different types depending on the presence of horizons. We show that these types are robust against changes in the system parameters and thus are genuine features of optical and non-optical analogues. These methods and findings pave the way to new observations of analogue gravity in dispersive systems.

Enabling Pulse-Level Programming, Compilation, and Execution in XACC

Noisy gate-model quantum processing units (QPUs) are currently available from vendors over the cloud, and digital quantum programming approaches exist to run low-depth circuits on physical hardware. These digital representations are ultimately lowered to pulse-level instructions by vendor quantum control systems to affect unitary evolution representative of the submitted digital circuit. Vendors are beginning to open this pulse-level control system to the public via specified interfaces. Robust programming methodologies, software frameworks, and backend simulation technologies for this analog model of quantum computation will prove critical to advancing pulse-level control research and development. Prototypical use cases for this include error mitigation, optimal pulse control, and physics-inspired pulse construction. Here we present an extension to the XACC quantum-classical software framework that enables pulse-level programming for superconducting, gate-model quantum computers, and a novel, general, and extensible pulse-level simulation backend for XACC that scales on classical compute clusters via MPI. Our work enables custom backend Hamiltonian definitions and gate-level compilation to available pulses with a focus on performance and scalability. We end with a demonstration of this capability, and show how to use XACC for pertinent pulse-level programming tasks.

Patient-Specific Blood Flow Analysis for Cerebral Arteriovenous Malformation Based on Digital Subtraction Angiography Images.

Real-time digital subtraction angiography (DSA) is capable of revealing the cerebral vascular morphology and blood flow perfusion patterns of arterial venous malformations (AVMs). In this study, we analyze the DSA images of a subject-specific left posterior AVM case and customize a generic electric analog model for cerebral circulation accordingly. The generic model consists of electronic components representing 49 major cerebral arteries and veins, and yields their blood pressure and flow rate profiles. The model was adapted by incorporating the supplying and draining patterns of the AVM to simulate some typical AVM features such as the blood “steal” syndrome, where the flow rate in the left posterior artery increases by almost three times (∼300 ml/min vs 100 ml/min) compared with the healthy case. Meanwhile, the flow rate to the right posterior artery is reduced to ∼30 ml/min from 100 ml/min despite the presence of an autoregulation mechanism in the model. In addition, the blood pressure in the draining veins is increased from 9 to 22 mmHg, and the blood pressure in the feeding arteries is reduced from 85 to 30 mmHg due to the fistula effects of the AVM. In summary, a first DSA-based AVM model has been developed. More subject-specific AVM cases are required to apply the presented in silico model, and in vivo data are used to validate the simulation results.

Optical analogue gravity physics: resonant radiation.

The photonic crystal fibre (PCF) is a unique medium giving us the opportunity to perform experiments in carefully chosen regimes with precision and control. Using PCFs, we can perform analogue gravity experiments to study the physics of Hawking radiation and related processes such as resonant radiation. We discuss the similarities and differences between these processes and experimentally investigate the limits of effects of this type, dis- covering a new regime of record efficiency. We measure a 60% energy conversion efficiency from a pump to a visible femtosecond pulse by the process of resonant radiation, and demonstrate its extraordinary tunability in wavelength and bandwidth. Beyond analogue gravity, these femtosecond visible pulses provide a desirable laser source useful across a variety of modern scientific fields. This article is part of a discussion meeting issue 'The next generation of analogue gravity experiments'.

Analogue gravity on a superconducting chip.

We describe how analogues of a Hawking evaporating black hole as well as the Unruh effect for an oscillatory, accelerating photodetector in vacuum may be realized using superconducting, microwave circuits that are fashioned out of Josephson tunnel junction and film bulk acoustic resonator elements. This article is part of a discussion meeting issue 'The next generation of analogue gravity experiments'.

The next generation of analogue gravity experiments.

This article is an introduction for a theme issue following a Scientific Discussion Meeting on \emph{The next generation of analogue gravity experiments} held at the Royal Society in December 2019. This theme issue comprises a collection of recent advances of the research programme, as well as their philosophical implications, that were presented at the meeting.

Estimate of the superradiance spectrum in dispersive media.

In 2016, the Nottingham group detected the rotational superradiance effect. While this experiment demonstrated the robustness of the superradiance process, it still lacks a complete theoretical description due to the many effects at stage in the experiment. In this paper, we shine new light on this experiment by deriving an estimate of the reflection coefficient in the dispersive regime by means of a Wentzel-Kramers-Brillouin analysis. This estimate is used to evaluate the reflection coefficient spectrum of counter-rotating modes in the Nottingham experiment. Our finding suggests that the vortex flow in the superradiance experiment was not purely absorbing, contrary to the event horizon of a rotating black hole. While this result increases the gap between this experimental vortex flow and a rotating black hole, it is argued that it is in fact this gap that is the source of novel ideas. This article is part of a discussion meeting issue 'The next generation of analogue gravity experiments'.

Dynamics landscape for acoustic superradiance.

We analyse the behaviour of acoustic vortex beams interacting with rotating, fluid-saturated porous materials. Regions of the parameter space that exhibit distinct dynamical features are identified, with a focus on features that are relevant to the characterization of rotational superradiance. We discuss the similarities and differences between two recent proposals to observe acoustic superradiance with rotating, air-saturated sound absorbers. Finally, theoretical predictions for macroscopic acoustic scattering, obtained by averaging over interactions between the fluid and the porous material at the microscopic level, are compared with predictions of the first-Born approximation. This article is part of a discussion meeting issue 'The next generation of analogue gravity experiments'.

Optical analogues of black-hole horizons.

Hawking radiation is unlikely to be measured from a real black hole, but can be tested in laboratory analogues. It was predicted as a consequence of quantum mechanics and general relativity, but turned out to be more universal. A refractive index perturbation produces an optical analogue of the black-hole horizon and Hawking radiation that is made of light. We discuss the central and recent experiments of the optical analogue, using hands-on physics. We stress the roles of classical fields, negative frequencies, 'regular optics' and dispersion. Opportunities and challenges ahead are briefly mentioned. This article is part of a discussion meeting issue 'The next generation of analogue gravity experiments'.

On the limits of experimental knowledge.

To demarcate the limits of experimental knowledge, we probe the limits of what might be called an experiment. By appeal to examples of scientific practice from astrophysics and analogue gravity, we demonstrate that the reliability of knowledge regarding certain phenomena gained from an experiment is not circumscribed by the manipulability or accessibility of the target phenomena. Rather, the limits of experimental knowledge are set by the extent to which strategies for what we call 'inductive triangulation' are available: that is, the validation of the mode of inductive reasoning involved in the source-target inference via appeal to one or more distinct and independent modes of inductive reasoning. When such strategies are able to partially mitigate reasonable doubt, we can take a theory regarding the phenomena to be well supported by experiment. When such strategies are able to fully mitigate reasonable doubt, we can take a theory regarding the phenomena to be established by experiment. There are good reasons to expect the next generation of analogue experiments to provide genuine knowledge of unmanipulable and inaccessible phenomena such that the relevant theories can be understood as well supported. This article is part of a discussion meeting issue 'The next generation of analogue gravity experiments'.

The case for a Casimir cosmology.

The cosmological constant, also known as dark energy, was believed to be caused by vacuum fluctuations, but naive calculations give results in stark disagreement with fact. In the Casimir effect, vacuum fluctuations cause forces in dielectric media, which is very well described by Lifshitz theory. Recently, using the analogy between geometries and media, a cosmological constant of the correct order of magnitude was calculated with Lifshitz theory (Leonhardt 2019 Ann. Phys. (New York) 411, 167973. (doi:10.1016/j.aop.2019.167973)). This paper discusses the empirical evidence and the ideas behind the Lifshitz theory of the cosmological constant without requiring prior knowledge of cosmology and quantum field theory.This article is part of a discussion meeting issue ‘The next generation of analogue gravity experiments’.