Perfect Simulation Research Articles

A hierarchical Bilayered scaffold for periodontal complex structure regeneration.

The periodontal tissue comprises alveolar bone, cementum, and periodontal ligament (PDL), forming a highly hierarchical architecture. Although current therapies could regenerate the hard tissue well, the simultaneous reconstruction of hard and soft tissue remains a great clinical challenge with the major difficulty in highly orientated PDL regeneration. Using the unidirectional freeze-casting method and biomimetic mineralization technique, we construct a hierarchical bilayer scaffold with the aligned chitosan scaffold with ZIF-8 resembling PDL, and intrafibrillarly mineralized collagen resembling alveolar bone. The hierarchical bilayer scaffold exhibits different geomorphic clues and chemical microenvironments to realize a perfect simulation of the natural periodontal hierarchical architecture. The aligned scaffold with ZIF-8 could induce the fibrogenic differentiation of bone mesenchymal stromal cells (BMSCs), and the mineralized scaffold could induce osteogenic differentiation of BMSCs. The hierarchical bilayer scaffold could simulate periodontal complex tissue, exhibiting great promise for synchronized multi-tissue regeneration of periodontal tissue.

Monte Carlo Tree Search in the Presence of Transition Uncertainty

Monte Carlo Tree Search (MCTS) is an immensely popular search-based framework used for decision making. It is traditionally applied to domains where a perfect simulation model of the environment is available. We study and improve MCTS in the context where the environment model is given but imperfect. We show that the discrepancy between the model and the actual environment can lead to significant performance degradation with standard MCTS. We therefore develop Uncertainty Adapted MCTS (UA-MCTS), a more robust algorithm within the MCTS framework. We estimate the transition uncertainty in the given model, and direct the search towards more certain transitions in the state space. We modify all four MCTS phases to improve the search behavior by considering these estimates. We prove, in the corrupted bandit case, that adding uncertainty information to adapt UCB leads to tighter regret bound than standard UCB. Empirically, we evaluate UA-MCTS and its individual components on the deterministic domains from the MinAtar test suite. Our results demonstrate that UA-MCTS strongly improves MCTS in the presence of model transition errors.

Perfect sampling of stochastic matching models with reneging

Abstract In this paper, we introduce a slight variation of the dominated-coupling-from-the-past (DCFTP) algorithm of Kendall, for bounded Markov chains. It is based on the control of a (typically non-monotonic) stochastic recursion by another (typically monotonic) one. We show that this algorithm is particularly suitable for stochastic matching models with bounded patience, a class of models for which the steady-state distribution of the system is in general unknown in closed form. We first show that the Markov chain of this model can easily be controlled by an infinite-server queue. We then investigate the particular case where patience times are deterministic, and this control argument may fail. In that case we resort to an ad-hoc technique that can also be seen as a control (this time, by the arrival sequence). We then compare this algorithm to the primitive coupling-from-the-past (CFTP) algorithm and to control by an infinite-server queue, and show how our perfect simulation results can be used to estimate and compare, for instance, the loss probabilities of various systems in equilibrium.

Effects of noise on information corruption in the quantum teleportation algorithm

In the quickly growing field of quantum computing, interference called “noise” causes discrepancies within the results of a quantum experiment. We aimed to observe the effects of noise on the quantum teleportation algorithm, which is used to transport the quantum state of one qubit to another qubit over distances. When the information in the teleportation algorithm is passed through noisy channels, the data can easily become corrupted. We conducted this study in order to observe the effects of noise on the information that travels through these channels. We aimed to understand the nature of the data corruption to help create improved and more faithful methods of data communication. Prior to conducting this study, we expected that the noise would have the most effect on the real and simulated backends and the least effect on the perfect backend. Through this study, we ran teleportation circuits on three different backends (a perfect simulation, a noisy simulation, and the real hardware) and compared the final results with our expected states. We observed that the predicted effects of noise on the information is accurate in some respects but that noise has the potential to drastically alter and corrupt the data. Moreover, the real hardware we used was far more susceptible to noise interference than the simulations. Our findings indicate that, to prevent the information from being compromised, other methods of noise reduction must be employed in conjunction with the quantum teleportation algorithm.

Ethical and Moral Issues Raised by Replicating the Moral Model Personality and Creating the Perfect Simulator

Ethical and Moral Issues Raised by Replicating the Moral Model Personality and Creating the Perfect Simulator

Skillful multiyear to decadal predictions of sea level in the North Atlantic Ocean and U.S. East Coast

Long-term sea-level rise and multiyear to decadal sea level variations pose substantial risks for flooding and erosion in coastal communities. Here we use observations and climate model predictions to show that sea level variations along the U.S. East Coast are skillfully predictable 3 to 10 years in advance. The most predictable component of sea level is a basin scale upward trend, predictable a decade in advance and primarily a response to increasing greenhouse gases. Significant additional predictability comes from multidecadal variations of the Atlantic Meridional Overturning Circulation (AMOC). While perfect model simulations show AMOC-related sea level predictability of 5-7 years, model biases and initialization uncertainties reduce the realized predictive skill to 3-5 years, depending on location. Overall, greenhouse gas warming and predictable AMOC variations lead to multiyear to decadal prediction skill for sea level along the U.S. East Coast. Such skill could have significant societal benefit for planning and adaptation.

The minimal communication cost for simulating entangled qubits

We analyze the amount of classical communication required to reproduce the statistics of local projective measurements on a general pair of entangled qubits,|ΨAB⟩=p |00⟩+1−p |11⟩(with1/2≤p≤1). We construct a classical protocol that perfectly simulates local projective measurements on all entangled qubit pairs by communicating one classical trit. Additionally, when2p(1−p)2p−1log⁡(p1−p)+2(1−p)≤1, approximately0.835≤p≤1, we present a classical protocol that requires only a single bit of communication. The latter model even allows a perfect classical simulation with an average communication cost that approaches zero in the limit where the degree of entanglement approaches zero (p→1). This proves that the communication cost for simulating weakly entangled qubit pairs is strictly smaller than for the maximally entangled one.

An Interacting Neuronal Network with Inhibition: theoretical analysis and perfect simulation

An Interacting Neuronal Network with Inhibition: theoretical analysis and perfect simulation

Unveiling the Performance of Nickel-Titanium Endodontic Instruments through Multimethod Research: A Review

This article aims to explore the importance of multimethod research in assessing the performance of nickel-titanium (NiTi) endodontic instruments. The review highlights the limitations of relying solely on measurements obtained through a narrow set of mechanical tests and acknowledges the challenge of replicating real-world working conditions in controlled laboratory settings. While achieving a perfect simulation may be difficult, the focus should be on developing research strategies that provide a superior understanding of outcomes. The multimethod research, which combines qualitative and quantitative methodologies, offers a promising solution to address this challenge effectively. By integrating nonquantifiable data with quantitative measurements, researchers may overcome the limitations of individual methodologies and gain deeper and more comprehensive insights into instrument performance. This multimethod approach enables a more accurate interpretation of results, enhancing the validity of the methodology. Therefore, conducting a comprehensive analysis of various competencies displayed by NiTi systems is essential for a comprehensive understanding of their characteristics, including cyclic fatigue, torsional and bending resistance, cutting efficiency, microhardness, design analysis, element composition, phase transformation temperatures, shaping ability, and additional methodologies that can address specific inquiries. By combining qualitative and quantitative methodologies in a multimethod approach, researchers can enhance their ability to answer research questions and provide valuable insights for clinical practice.

Swarm Intelligence in Cooperative Environments: -Step Dynamic Tree Search Algorithm Overview

Reinforcement learning tree-based planning methods have been gaining popularity in the last few years due to their success in single-agent domains, where a perfect simulator model is available: for example, Go and chess strategic board games. This paper pretends to extend tree search algorithms to the multiagent setting in a decentralized structure, dealing with scalability issues and exponential growth of computational resources. The dynamic tree search combines forward planning and direct temporal-difference updates, outperforming markedly conventional tabular algorithms such as learning and state-action-reward-state-action (SARSA). Future state transitions and rewards are predicted with a model built and learned from real interactions between agents and the environment. This paper analyzes the developed algorithm in the hunter–pursuit cooperative game against stochastic and intelligent evaders. The dynamic tree search aims to adapt single-agent tree search learning methods to the multiagent boundaries and is demonstrated to be a remarkable advance as compared to conventional temporal-difference techniques.

“Bridging the Gap” international ECLS training and simulation - evaluation of the 10th educational corner on EuroELSO congress 2022 in London, United Kingdom

Introduction: Simulation training offers an authentic team-based learning opportunity without risk to real patients. The Educational Corner at the annual congress of the European Branch of Extracorporeal Life Support Organisation (EuroELSO) provided an opportunity for multiple simulation training sessions facilitated by experts from all over the world.Aim: We aimed to review the educational impact of EuroELSO Educational Corner and whether it provides a quality ECLS training to a wide spectrum of multidisciplinary international attendees utilising high and low fidelity simulation, workshops and hands on sessions.Methods: During the congress, 43 sessions were conducted dedicated to ECLS education with identified educational objectives. The sessions focused on management of adults and children on V-V or V-A ECMO. Adult sessions covered emergencies on mechanical circulatory support with management of LVAD and Impella, managing refractory hypoxemia on V-V ECMO, emergencies on ECMO, renal replacement therapy on ECMO, V-V ECMO, ECPR cannulation and performing perfect simulation. Paediatric sessions covered ECPR neck and central cannulation, renal replacement on ECMO, troubleshooting, cannulation workshop, V-V recirculation, ECMO for single ventricle, PIMS-TS and CDH, ECMO transport and neurological injury.Results: The Educational Corner was attended by more than 400 participants over the two congress days. Majority of responders (88%) reported that training sessions met the set educational goals and objectives and that this would change their current practice. Almost all (94%) reported that they received useful information and 95% would recommend the session to their colleagues.Conclusion: The Educational Corner, as an integral component of the annual EuroELSO congress, achieved the set educational goals and provided quality education based on the recipient survey. Structured multidisciplinary ECLS education with standardised curriculum and feedback is an important key step in delivering quality training to an international audience. Standardisation of European ECLS education remains an important focus of the EuroELSO.

Simulation study on the interaction between the battery module and busbar under typical driving conditions of electric vehicles

Accurate simulation of the battery thermoelectric coupling characteristics is the key to the thermal design and thermal management. As the electrically connected component between the battery electrodes, the heat production and heat transfer of the busbars have a significant impact on the battery thermoelectric behavior. A small number of battery thermal management studies have begun to model busbars recently, but the thickness, length, and material of the busbars are diverse. There is a lack of perfect simulation analysis and optimization methods. There is an urgent need to conduct in-depth research on the influence of characteristic parameters of the busbars on the battery thermoelectric behavior. Based on the MSMD-NTGK model, this paper investigates the influence of the thickness, length, and material of the busbars on the battery thermoelectric behavior without considering the economic cost and differences in the battery structure design. In this paper, a simulation analysis method and an ideal improvement solution for the design of the busbars are proposed. This paper compares the changes in the battery thermal behavior before and after the improvement of the busbars under the constant-rate discharge process, FTP75 condition, NEDC condition and WLTC condition respectively. This study can improve the realism of the battery thermal behavior simulation, provide a reliable simulation analysis method and reference basis for the industrial design and optimization of the busbars, and further improve the reliability of the subsequent battery thermal management simulation.

Classical Cost of Transmitting a Qubit.

We consider general prepare-and-measure scenarios in which Alice can transmit qubit states to Bob, who can perform general measurements in the form of positive operator-valued measures (POVMs). We show that the statistics obtained in any such quantum protocol can be simulated by the purely classical means of shared randomness and two bits of communication. Furthermore, we prove that two bits of communication is the minimal cost of a perfect classical simulation. In addition, we apply our methods to Bell scenarios, which extends the well-known Toner and Bacon protocol. In particular, two bits of communication are enough to simulate all quantum correlations associated to arbitrary local POVMs applied to any entangled two-qubit state.

Long-term stability and generalization of observationally-constrained stochastic data-driven models for geophysical turbulence

Abstract Recent years have seen a surge in interest in building deep learning-based fully data-driven models for weather prediction. Such deep learning models, if trained on observations can mitigate certain biases in current state-of-the-art weather models, some of which stem from inaccurate representation of subgrid-scale processes. However, these data-driven models, being over-parameterized, require a lot of training data which may not be available from reanalysis (observational data) products. Moreover, an accurate, noise-free, initial condition to start forecasting with a data-driven weather model is not available in realistic scenarios. Finally, deterministic data-driven forecasting models suffer from issues with long-term stability and unphysical climate drift, which makes these data-driven models unsuitable for computing climate statistics. Given these challenges, previous studies have tried to pre-train deep learning-based weather forecasting models on a large amount of imperfect long-term climate model simulations and then re-train them on available observational data. In this article, we propose a convolutional variational autoencoder (VAE)-based stochastic data-driven model that is pre-trained on an imperfect climate model simulation from a two-layer quasi-geostrophic flow and re-trained, using transfer learning, on a small number of noisy observations from a perfect simulation. This re-trained model then performs stochastic forecasting with a noisy initial condition sampled from the perfect simulation. We show that our ensemble-based stochastic data-driven model outperforms a baseline deterministic encoder–decoder-based convolutional model in terms of short-term skills, while remaining stable for long-term climate simulations yielding accurate climatology.

Estimation of the last passage percolation constant in a charged complete directed acyclic graph via perfect simulation

Our object of study is the asymptotic growth of heaviest paths in a charged (weighted with signed weights) complete directed acyclic graph. Edge charges are i.i.d. random variables with common distribution $F$ supported on $[−\infty, 1$] with essential supremum equal to 1 (a charge of $−\infty$ is understood as the absence of an edge). The asymptotic growth rate is a constant that we denote by $C(F)$. Even in the simplest case where $F = p\delta_1 + (1 − p)\delta_{-\infty}$, corresponding to the longest path in the Barak-Erdős random graph, there is no closed-form expression for this function, but good bounds do exist. In this paper we construct a Markovian particle system that we call Max Growth System (MGS), and show how it is related to the charged random graph. The MGS is a generalization of the Infinite Bin Model that has been the object of study of a number of papers. We then identify a random functional of the process that admits a stationary version and whose expectation equals the unknown constant $C(F)$. Furthermore, we construct an effective perfect simulation algorithm for this functional which produces samples from the random functional.

Reality+: Virtual Worlds and the Problems of Philosophy by David J. Chalmers

Reviewed by: Reality+: Virtual Worlds and the Problems of Philosophy by David J. Chalmers Anand Jayprakash Vaidya (bio) Reality+: Virtual Worlds and the Problems of Philosophy. By David J. Chalmers. New York, NY: W.W Norton & Company, 2022. Pp. xi + 520. Hardcover $22.49, isbn 978-0-393635-80-5. It isn't uncommon to think that virtual worlds, the worlds we engage with in video games, for example, are not real or at least less real than the ordinary world. After all, they are worlds that are created by us, and thus are less real than the world we didn't create, mind-independent reality. However, in Reality+, David Chalmers argues for the thesis that virtual reality is genuine reality. Reality+ is the twenty-first century equivalent of Bertrand Russell's twentieth century The Problems of Philosophy, published 110 years prior. Like Russell, Chalmers' goal is to explain the basic problems of philosophy to a wide audience. The book's twenty-four chapters are organized into seven different parts: virtual worlds, knowledge, reality, real virtual reality, mind, value, and foundations. Each section has about three to four chapters. Having taught the book in an upper-division philosophy of mind course, I would say that the first nine chapters should be read together to get a good sense of the whole project, because they give shape and structure to Chalmers' basic arguments and positions. The following fifteen self-explanatory, self-contained, chapters, are independently engaging, and can be taught separately, as standalone works of philosophy. Chalmers engages in what he terms technophilosophy, which is the combination of (1) asking philosophical questions about technology and (2) using technology to help answer traditional questions of philosophy. He claims that he draws inspiration for the project from Patricia Churchland's 1986 Neurophilosophy, where she does the equivalent of (1) and (2) with neuroscience. Reality+ delivers clear arguments, referencing historical and contemporary philosophical work, while frequently drawing from science fiction, including several outstanding Rick and Morty -style illustrations. The use of science fiction helps to connect students to abstract ideas, while the robustly constructed arguments serve to instruct students on how to go about critically examining the ideas. My students found the book accessible and engaging. I imagine the book [End Page 1] will become even more relevant to successive classes, as the issues Chalmers discusses grow more dominant in the future. Chapter 1, "Is this the real life?", begins by discussing Indian and Chinese philosophy in relation to Greek philosophy with respect to theme of illusion/dreams vs. reality. In all three traditions, one finds discussion of the nature of reality and whether we can know it. Chalmers thinks that each of these traditions helps to formulate the basic questions of his book: the knowledge question, the reality question, and the value question. The knowledge question: can we know whether or not we are living in a virtual world? In part 2, Chalmers argues that we cannot know that we are not living in a virtual world. He does so by defending his own version of Nick Bostrom's simulation argument (2003), which very roughly goes as follows: (1) If there is nothing (technological or otherwise) that would serve to block the creation of a perfect simulation of a humanlike being into existence (what he calls a sim blocker), then most humanlike beings are simulations. (2) if most humanlike beings are simulations, we are probably simulations. So, (3) if there are no sim blockers, we are probably sims. The reality question: are virtual worlds real? He argues that virtual worlds are genuinely real by examining a variety of definitions of what makes something real in chapter 6. I will examine this argument in more detail in the following section. The value question: can you lead a good life in a virtual world? He argues that one can, in parts 5 and 6. He says: "In principle, life in virtual reality can have the same sort of value as life in nonvirtual reality. To be sure, life in virtual reality can be good or bad" (p. 311). As successful as Reality+ is, philosophical counterpoints arose in my mind. In the next section, I present...

Impact of Assimilating Radar Data with 3D Thermodynamic Fields in an Ensemble Kalman Filter: Proof of Concept and Feasibility

Abstract This study examined the impact of assimilating 3D temperature and water vapor information in addition to radar observations in a multiscale weather system. A frontal system with extremely heavy rainfall over northern Taiwan was selected. Using the WRF–LETKF Radar Assimilation System, we performed three sets of observing system simulation experiments to assimilate radar observations with or without thermodynamic variables obtained using different methods. First, assimilating the radar data for 2 h showed better structure and short-term forecast than 1 h. Second, we assimilated radar data and thermodynamic variables from a perfect model simulation. The results of the analysis revealed that when a precipitation position error occurred in the background field, assimilating thermodynamic information with the radar data could correct the dynamic structure and shorten the spinup assimilation period, resulting in substantial improvements to the quantitative precipitation forecast. Third, we applied a thermodynamics retrieval algorithm for a feasibility study. With a warm and wet bias of the retrieved fields, assimilating the temperature data had significant impact on the midlevel of stratiform areas and the forecast of the heavy rainfall was consequently improved. Assimilating the water vapor information helped reconstruct the range and intensity of the cold pool, but the improvement of rainfall forecast was limited. The optimal results of analysis and short-term forecast were achieved when both retrieved temperature and water vapor fields were assimilated. In conclusion, assimilating thermodynamic variables in the precipitation system is feasible for shortening the spinup period of data assimilation and improving the analysis and short-term forecast.

Race, But Not Gender, Is Associated With Admissions Into Orthopaedic Residency Programs.

Orthopaedic surgery is one of the most competitive but least diverse surgical specialties, with ever-increasing academic achievements (such as test scores) shown by applicants. Prior research shows that white applicants had higher United States Medical Licensing Exam (USMLE) Step 1 and Step 2 Clinical Knowledge scores as well as higher odds of Alpha Omega Alpha status compared with Black, Hispanic, and other applicant groups. Yet, it still remains unknown whether differences in application metrics by race/ethnicity sufficiently explain the underrepresentation of certain racial or ethnic minority groups in orthopaedic residency programs. In this study, we sought to determine (1) the relative weight of academic variables for admission into orthopaedic residency, and (2) whether race and gender are independently associated with admission into an orthopedic residency. The Electronic Residency Application System (ERAS) data from the Association of American Medical Colleges (AAMC) and the National Board of Medical Examiners (NBME) of first-time MD applicants (n = 8966) for orthopaedic surgery residency positions in the United States and of admitted orthopaedic residents (n = 6218) from 2005 to 2014 were reviewed. This dataset is the first and most comprehensive of its kind to date in orthopaedic surgery. Academic metrics, such as USMLE Step 1 and Step 2 Clinical Knowledge scores, number of publications, Alpha Omega Alpha status, volunteer experiences, work experience, as well as race and gender, were analyzed using hierarchical logistic regression models. The first model analyzed the association of academic metrics with admission into orthopaedic residency. In the second model, we added race and gender and controlled for metrics of academic performance. To determine how well the models simulated the actual admissions data, we computed the receiver operating characteristics (ROC) including the area under curve (AUC), which measures the model's ability to simulate which applicants were admitted or not admitted, with an AUC = 1.0 representing a perfect simulation. The odds ratio and confidence interval of each variable were computed. When only academic variables were analyzed in the first model, Alpha Omega Alpha status (odds ratio 2.12 [95% CI 1.80 to 2.50]; p < 0.001), the USMLE Step 1 score (OR 1.04 [95% CI 1.03 to 1.04]; p < 0.001), the USMLE Step 2 Clinical Knowledge score (OR 1.01 [95% CI 1.01 to 1.02]; p < 0.001), publication count (OR 1.04 [95% CI 1.03 to 1.05]; p < 0.001), and volunteer experience (OR 1.03 [95% CI 1.01 to 1.04]; p < 0.001) were associated with admissions into orthopaedics while work and research experience were not. This model yielded a good prediction of the results with an AUC of 0.755. The second model, in which the variables of race and gender were added to the academic variables, also had a good prediction of the results with an AUC of 0.759. This model indicates that applicant race, but not gender, is associated with admissions into orthopaedic residency. Applicants from Asian (OR 0.78 [95% CI 0.67 to 0.92]), Black (OR 0.63 [95% CI 0.51 to 0.77], Hispanic (OR 0.48 [95% CI 0.36 to 0.65]), or other race groups (OR 0.65 [95% CI 0.55 to 0.77]) had lower odds of admission into residency compared with white applicants. Minority applicants, but not women, have lower odds of admission into orthopaedic surgery residency, even when accounting for academic performance metrics. Changes in the residency selection processes are needed to eliminate the lower admission probability of qualified minority applicants in orthopaedic residency and to improve the diversity and inclusion of orthopaedic surgery. Changes including increasing the diversity of the selection committee, bias training, blinding applications before review, removal of metrics with history of racial disparities from an interviewer's candidate profile before an interview, and use of holistic application review (where an applicants' experiences, attributes, and academic metrics are all considered) can improve the diversity landscape in training. In addition, cultivating an environment of inclusion will be necessary to address these long-standing trends in orthopaedic surgery. Race, but not gender, is associated with the odds of acceptance into orthopaedic surgery residency despite equivalent academic metrics. Changes in residency selection processes are suggested to eliminate the lower admission probability of qualified minority applicants into orthopaedic residency and to improve the diversity and inclusion of orthopaedic surgery.

Influences of Parameter Deviation on the Vibration Isolation System of an End Effector

The vibration problem influences the precision of the equipment. However, some vibration isolation systems (VISs) with the perfect theoretical and simulation results are still unable to suppress the vibration well, resulting in the damage during the operation, such as the phenomenon of fragments for the end effector of a glass substrate handling robot. Therefore, this paper focuses on the glass substrate handling robot in actual production and simplifies the VIS into a 2D (2 degree) system. From the analysis of the deviation of material parameters and installation deviations between vibration isolators, this paper concludes that, as long as there is a deviation, the vibration isolation performance of the system will be reduced. Through the mutually verified theory, simulation, and experimental structure, this paper also presents that the resonance frequency increase factor of the vibration isolation system is approximately the deviation. As for the end effector, the distance of the two vibration isolations is 579.4 mm. The change of the load does not change the isolation frequency of the same system, but the resonance amplitude will increase. The results of this study can supervise the installation and selection of vibration isolators in VISs. At the same time, the reasons for the weak vibration isolation performance of some systems are explained.

Shock/expansion fan interaction with real gas effects for Earth and Mars atmospheric conditions

AbstractNumerical simulations are performed to investigate the real gas effects on shock/expansion fan interaction. Initial perfect gas simulations at low enthalpy capture the flow structures efficiently and outcomes are found to have excellent agreement with the analytical calculations. Furthermore, the simulations with the real gas solver for different enthalpies showed that the variation in enthalpy significantly changes the flow structures. It is observed that an increase in enthalpy leads to a decrease and increase in the postshock and postexpansion fan Mach numbers, respectively. Another important observation is the decrement in the peak pressure ratio with an increment in the enthalpy. These effects are noted to be more pronounced for Mars's environment due to the higher dependency of specific heat on temperature.