Dynamical Arguments Research Articles

Discovery of a Brown Dwarf with Quasi-spherical Mass Loss

We report the serendipitous discovery of an elliptical shell of CO associated with the faint stellar object SSTc2d J163134.1-240060 as part of the “Ophiuchus Disk Survey Employing ALMA” (ODISEA), a project aiming to study the entire population of protoplanetary disks in the Ophiuchus Molecular Cloud from 230 GHz continuum emission and 12CO (J = 2–1), 13CO (J = 2–1) and C18CO (J = 2–1) lines readable in Band 6. Remarkably, we detect a bright 12CO elliptical shape emission of ∼3″ × 4″ toward SSTc2d J163134.1-240060 without a 230 GHz continuum detection. Based on the observed near-IR spectrum taken with the Very Large Telescope (KMOS), the brightness of the source, its three-dimensional motion, and Galactic dynamic arguments, we conclude that the source is not a giant star in the distant background (>5–10 kpc) and is most likely to be a young brown dwarf in the Ophiuchus cloud, at a distance of just ∼139 pc. This is the first report of quasi-spherical mass loss in a young brown dwarf. We suggest that the observed shell could be associated with a thermal pulse produced by the fusion of deuterium, which is not yet well understood, but for a substellar object is expected to occur during a short period of time at an age of a few Myr, in agreement with the ages of the objects in the region. Other more exotic scenarios, such as a merger with planetary companions, cannot be ruled out from the current observations.

New binaries from the SHINE survey

We present the multiple stellar systems observed within the SpHere INfrared survey for Exoplanet (SHINE). SHINE searched for sub-stellar companions to young stars using high contrast imaging. Although stars with known stellar companions within the SPHERE field of view (< 5.5 arcsec) were removed from the original target list, we detected additional stellar companions to 78 of the 463 SHINE targets observed so far. Twenty-seven per cent of the systems have three or more components. Given the heterogeneity of the sample in terms of observing conditions and strategy, tailored routines were used for data reduction and analysis, some of which were specifically designed for these datasets. We then combined SPHERE data with literature and archival data, TESS light curves, and Gaia parallaxes and proper motions for an accurate characterisation of the systems. Combining all data, we were able to constrain the orbits of 25 systems. We carefully assessed the completeness of our sample for separations between 50–500 mas (corresponding to periods of a few years to a few decades), taking into account the initial selection biases and recovering part of the systems excluded from the original list due to their multiplicity. This allowed us to compare the binary frequency for our sample with previous studies and highlight interesting trends in the mass ratio and period distribution. We also found that, when such an estimate was possible, the values of the masses derived from dynamical arguments were in good agreement with the model predictions. Stellar and orbital spins appear fairly well aligned for the 12 stars that have enough data, which favours a disk fragmentation origin. Our results highlight the importance of combining different techniques when tackling complex problems such as the formation of binaries and show how large samples can be useful for more than one purpose.

Enforcement Heuristics for Argumentation with Deep Reinforcement Learning

In this paper, we present a learning-based approach to the symbolic reasoning problem of dynamic argumentation, where the knowledge about attacks between arguments is incomplete or evolving. Specifically, we employ deep reinforcement learning to learn which attack relations between arguments should be added or deleted in order to enforce the acceptability of (a set of) arguments. We show that our Graph Neural Network (GNN) architecture EGNN can learn a near optimal enforcement heuristic for all common argument-fixed enforcement problems, including problems for which no other (symbolic) solvers exist. We demonstrate that EGNN outperforms other GNN baselines and on enforcement problems with high computational complexity performs better than state-of-the-art symbolic solvers with respect to efficiency. Thus, we show our neuro-symbolic approach is able to learn heuristics without the expert knowledge of a human designer and offers a valid alternative to symbolic solvers. We publish our code at https://github.com/DennisCraandijk/DL-Abstract-Argumentation.

Synthesizing evidence from clinical trials with dynamic interactive argument trees

BackgroundEvidence-based medicine propagates that medical/clinical decisions are made by taking into account high-quality evidence, most notably in the form of randomized clinical trials. Evidence-based decision-making requires aggregating the evidence available in multiple trials to reach –by means of systematic reviews– a conclusive recommendation on which treatment is best suited for a given patient population. However, it is challenging to produce systematic reviews to keep up with the ever-growing number of published clinical trials. Therefore, new computational approaches are necessary to support the creation of systematic reviews that include the most up-to-date evidence.We propose a method to synthesize the evidence available in clinical trials in an ad-hoc and on-demand manner by automatically arranging such evidence in the form of a hierarchical argument that recommends a therapy as being superior to some other therapy along a number of key dimensions corresponding to the clinical endpoints of interest. The method has also been implemented as a web tool that allows users to explore the effects of excluding different points of evidence, and indicating relative preferences on the endpoints.ResultsThrough two use cases, our method was shown to be able to generate conclusions similar to the ones of published systematic reviews. To evaluate our method implemented as a web tool, we carried out a survey and usability analysis with medical professionals. The results show that the tool was perceived as being valuable, acknowledging its potential to inform clinical decision-making and to complement the information from existing medical guidelines.ConclusionsThe method presented is a simple but yet effective argumentation-based method that contributes to support the synthesis of clinical trial evidence. A current limitation of the method is that it relies on a manually populated knowledge base. This problem could be alleviated by deploying natural language processing methods to extract the relevant information from publications.

Insights into beliefs on 11 + testing in Trinidad and Tobago through an interpretation/use argument

In the Caribbean there is still strong public belief in and support for the value and potency of early high stakes examinations at the end of primary school. This belief system is based upon the perceived plausibility and credibility of policy claims and arguments. To decipher the belief system, an interpretation/use argument protocol was used. After extracting and explicating policy claims, Q-Methodology was employed to judge the perceived value of each policy claim for parents, teachers, and students. Q-analysis data were interpreted using a typology constructed from mass social movement theory. The 3 ideal types identified were True Believers, Reluctant Believers, and Non-Believers. Variants of each type were related to specific policy issues. True and Reluctant Believers constitute the majority of parents and teachers. The largest number of Non-Believers were for teachers. Dynamic and changing policy arguments appear to buttress the believability of early high-stakes testing in this context.

Argumentation Frameworks – A Brief Review

The main aim of this article is to provide a short review of the most important argumentation frameworks (AFs) systems being used. This paper presents the overall thought of unique argumentation, featuring the work way of these theoretical systems in the argumentation interaction and surveys the first Dung structures. It introduces how these systems give acceptable arguments by focused on the argumentation frameworks structures and how to deal with the arguments and the basic rules to give the result. Finally, it surveys the idea of theoretical rationalistic structures, quite possibly the broadest frameworks for dynamic argumentation, and gives a short description of several argumentation frameworks that are more famous.

Optimal Consumption and Life Insurance Under Shortfall Aversion and a Drawdown Constraint

This paper studies a life-cycle optimal portfolio-consumption problem when the consumption performance is measured by a shortfall aversion preference with an additional drawdown constraint on consumption rate. Meanwhile, the agent also dynamically chooses her life insurance premium to maximize the expected bequest at the death time. By using dynamic programming arguments and the dual transform, we solve the HJB variational inequality explicitly in a piecewise form across different regions and derive some thresholds of the wealth variable for the piecewise optimal feedback controls. Taking advantage of our analytical results, we are able to numerically illustrate some quantitative impacts on optimal consumption and life insurance by model parameters and discuss their financial implications.

عالمية الدعوة القرآنية للسلام وسبل تقريبها: قراءة في التفسير المنهاجي للإمام عبد السلام ياسين

The problem statement of this research is about Imam Yassine’s thought in his reading of Islamic past and present and Western intellectual trends, and about his long experience in the field of Da’wah, as Imam Yassine urged Muslims to be capable of handling the mission of the holy Quran. It becomes more complicated with Al-Tafsir al-Minhaji as an approach to interpret the holy Quran and ease it for Muslim youth understanding in Imam Yassine’s books about thought, education, Da’wah, mysticism and civilization. This research aims to explain how Al-Tafsir al-Minhaji concerns about the method of practicing Quranic interpretation in Da’wah for Muslim Ummah renaissance. The research also aims to highlight that achieving global peace is one of main Quranic objective that Muslim thinkers are paying a great attention to its role in dialogue between variant sectarianists and theologians. Researchers followed the descriptive and inductive methods to explore Yassine’s views about peace, civilization and argumentation. Some findings of this research: Imam Yassine confirms the necessity of coincidence between the Quranic objectives and political objectives; and calls for dialogue based on Quranic objectives and its component of wisdom and dynamic argumentation, which leads to peace. To understand the fluctuation of history in the light of Quranic exegesis, Imam Yassine scrutinized the Quranic objectives of peaceful coexistence and cultural exchange.

Age-dating Red Giant Stars Associated with Galactic Disk and Halo Substructures

Abstract The vast majority of Milky Way stellar halo stars were likely accreted from a small number (≲3) of relatively large dwarf galaxy accretion events. However, the timing of these events is poorly constrained and predominantly relies on indirect dynamical mixing arguments or imprecise age measurements of stars associated with debris structures. Here, we aim to infer robust stellar ages for stars associated with galactic substructures to more directly constrain the merger history of the Galaxy. By combining kinematic, asteroseismic, and spectroscopic data where available, we infer stellar ages for a sample of 10 red giant stars that were kinematically selected to be within the stellar halo, a subset of which are associated with the Gaia–Enceladus–Sausage halo substructure, and compare their ages to 3 red giant stars in the Galactic disk. Despite systematic differences in both absolute and relative ages determined here, age rankings of stars in this sample are robust. Passing the same observable inputs to multiple stellar age determination packages, we measure a weighted average age for the Gaia–Enceladus–Sausage stars in our sample of 8 ± 3 (stat.) ± 1 (sys.) Gyr. We also determine hierarchical ages using isochrones for the populations of Gaia–Enceladus–Sausage, in situ halo and disk stars, finding a Gaia–Enceladus–Sausage population age of 8.0 − 2.3 + 3.2 Gyr. Although we cannot distinguish hierarchical population ages of halo or disk structures with our limited data and sample of stars, this framework should allow a distinct characterization of Galactic substructures using larger stellar samples and additional data available in the near future.

Incremental Computation in Dynamic Argumentation Frameworks

Dealing with controversial information is a challenging and important task for intelligent systems. Formal argumentation enables reasoning on arguments for and against a claim to decide on an outcome. An argumentation framework often models a dynamic situation where arguments as well as the way they interact frequently change over the time. As a consequence, the sets of accepted arguments (i.e., extensions under a given semantics) often need to be computed again after performing an update. In this article, we address the problem of efficiently recomputing extensions of dynamic argumentation frameworks. We present an incremental algorithmic solution whose main idea is that of using an initial extension and the update to identify a (potentially small) portion of the argumentation framework, which is sufficient to compute an extension of the whole updated framework.

Semi-empirical linear correlation between surface tension and thermodynamics properties of liquids and vapours

Abstract There are three interpretations of surface tension in the scientific literature based on phenomenological, thermodynamics and molecular dynamics arguments. The equivalence between phenomenological and thermodynamics interpretations is well known, but there is no explicit model to connect them with the principles of molecular dynamics. In molecular dynamics the concept of pressure is divided into two independent contributions referred as kinetic and cohesive. In this study a semi-empirical model of surface tension is proposed based on unbalanced intermolecular forces at the interphases. The model incorporates elements from the previous three interpretations and recognizes the existence of kinetic and cohesive contributions to pressure. Published experimental data of surface tension is used to determine the two model empirical parameters representing the thickness of interphases and average intermolecular forces. The results show that the proposed model correctly predicts a linear relationship between surface tension and thermodynamics properties of liquids and vapours in equilibrium.

Incremental Skeptical Preferred Acceptance in Dynamic Argumentation Frameworks

In this article, we tackle the problem of efficiently recomputing the skeptical acceptance of dynamic argumentation frameworks under the well-known preferred semantics. We discuss an incremental algorithmic solution whose main idea is that of exploiting the initial knowledge (including the update to perform) in order to identify a potentially small portion of the argumentation framework. Such a portion is sufficient to compute the skeptical preferred acceptance of a goal argument w.r.t. the whole updated framework. We also discuss on how similar ideas extend to more general argumentation frameworks.

Utility Maximization with Proportional Transaction Costs Under Model Uncertainty

We consider a discrete time financial market with proportional transaction costs under model uncertainty and study a numéraire-based semistatic utility maximization problem with an exponential utility preference. The randomization techniques recently developed in Bouchard, Deng, and Tan [Bouchard B, Deng S, Tan X (2019) Super-replication with proportional transaction cost under model uncertainty. Math. Finance 29(3):837–860.], allow us to transform the original problem into a frictionless counterpart on an enlarged space. By suggesting a different dynamic programming argument than in Bartl [Bartl D (2019) Exponential utility maximization under model uncertainty for unbounded endowments. Ann. Appl. Probab. 29(1):577–612.], we are able to prove the existence of the optimal strategy and the convex duality theorem in our context with transaction costs. In the frictionless framework, this alternative dynamic programming argument also allows us to generalize the main results in Bartl [Bartl D (2019) Exponential utility maximization under model uncertainty for unbounded endowments. Ann. Appl. Probab. 29(1):577–612.] to a weaker market condition. Moreover, as an application of the duality representation, some basic features of utility indifference prices are investigated in our robust setting with transaction costs.

Concentration estimates in a multi-host epidemiological model structured by phenotypic traits

In this work we consider a nonlocal system modelling the evolutionary adaptation of a pathogen within a multi-host population of plants. Here we focus our analysis on the study of the stationary states. We first discuss the existence of nontrivial equilibria using dynamical system arguments. Then we introduce a small parameter 0<ε≪1 that characterises the width of the mutation kernel, and we describe the asymptotic shape of steady states with respect to ε. In particular, for ε→0 we show that the distribution of the pathogen approaches a singular measure concentrated on the maxima of fitness in each plant population. This asymptotic description allows us to show the local stability of each of the positive steady states for ε≪1, from which we deduce a uniqueness result for the nontrivial stationary states by means of a topological degree argument. These analyses rely on a careful investigation of the spectral properties of some nonlocal operators.

Optimal management of pumped hydroelectric production with state constrained optimal control

We present a novel technique to solve the problem of managing optimally a pumped hydroelectric storage system. This technique relies on representing the system as a stochastic optimal control problem with state constraints, these latter corresponding to the finite volume of the reservoirs. Following the recent level-set approach presented in O. Bokanowski, A. Picarelli, H. Zidani, State-constrained stochastic optimal control problems via reachability approach, SIAM J. Control and Optim. 54 (5) (2016), we transform the original constrained problem in an auxiliary unconstrained one in augmented state and control spaces, obtained by introducing an exact penalization of the original state constraints. The latter problem is fully treatable by classical dynamic programming arguments.

Dynamic Kibble-Zurek scaling framework for open dissipative many-body systems crossing quantum transitions

We study the quantum dynamics of many-body systems, in the presence of dissipation due to the interaction with the environment, under Kibble-Zurek (KZ) protocols in which one Hamiltonian parameter is slowly, and linearly in time, driven across the critical value of a zero-temperature quantum transition. In particular we address whether, and under which conditions, open quantum systems can develop a universal dynamic scaling regime similar to that emerging in closed systems. We focus on a class of dissipative mechanisms whose dynamics can be reliably described through a Lindblad master equation governing the time evolution of the system's density matrix. We argue that a dynamic scaling limit exists even in the presence of dissipation, whose main features are controlled by the universality class of the quantum transition. This requires a particular tuning of the dissipative interactions, whose decay rate $u$ should scale as $u\sim t_s^{-\kappa}$ with increasing the time scale $t_s$ of the KZ protocol, where the exponent $\kappa = z/(y_\mu+z)$ depends on the dynamic exponent $z$ and the renormalization-group dimension $y_\mu$ of the driving Hamiltonian parameter. Our dynamic scaling arguments are supported by numerical results for KZ protocols applied to a one-dimensional fermionic wire undergoing a quantum transition in the same universality class of the quantum Ising chain, in the presence of dissipative mechanisms which include local pumping, decay, and dephasing.

Dynamic organization model of automated negotiation for 3PL providers selection

To keep their competitive edge and improve customer satisfaction, it is popular for many companies to outsource their logistics to proper Third-Party Logistics (3PL) providers. The evaluation and selection of 3PL providers in their business processes are expected to be solved dynamically. In this paper, based on the theory of automated negotiation, a Dynamic Organization Model (DOM) was designed for an online E-commerce Platform (EP) from the perspective of companies outsourcing logistics. During the negotiation, the involved 3PL provider agents may autonomously make decisions upon both the negotiation context and the dynamic market arguments in an iterative manner, and both the basic attributes of 3PL providers and the historical cooperation data with them are considered. Through comprehensive evaluation and negotiation, the most suitable 3PL provider may be determined as the contractual partner. Finally, the effectiveness of DOM is testified by a case study instantiated with a coal company and several 3PL providers.

Ultra-light Dark Matter Is Incompatible with the Milky Way’s Dwarf Satellites

Abstract The density profiles of dwarf galaxies are a highly varied set. If the dark matter is an ultra-light particle such as axions, then simulations predict a distinctive and unique profile. If the axion mass is large enough to fit the ultra-faint dwarf (UFD) satellites ( eV), then the models do not fit the density profile of Fornax and Sculptor and are ruled out by more than confidence. If the axion mass is in the mass range that can fit mass profiles of Fornax and Sculptor dwarf spheroidals, then its extended profile implies enormous masses ( ) for the UFDs. These large masses for the UFDS are ruled out by more than confidence by dynamical friction arguments. The tension would increase further considering star formation histories and stellar masses of the UFDs. Unless future ultra-light dark matter (ULDM) simulations with baryonic feedback show a significant change in the density structure of the halos, the current data is incompatible with the ULDM scenario. Relaxing the slope constraint from classical dwarf galaxies would lead to excluding ULDM with mass less than .

Brittle yielding of amorphous solids at finite shear rates

Amorphous solids display a ductile to brittle transition as the kinetic stability of the quiescent glass is increased, which leads to a material failure controlled by the sudden emergence of a macroscopic shear band in quasi-static protocols. We numerically study how finite deformation rates influence ductile and brittle yielding behaviors using model glasses in two and three spatial dimensions. We find that a finite shear rate systematically enhances the stress overshoot of poorly-annealed systems, without necessarily producing shear bands. For well-annealed systems, the non-equilibrium discontinuous yielding transition is smeared out by finite shear rates and it is accompanied by the emergence of multiple shear bands that have been also reported in metallic glass experiments. We show that the typical size of the bands and the distance between them increases algebraically with the inverse shear rate. We provide a dynamic scaling argument for the corresponding lengthscale, based on the competition between the deformation rate and the propagation time of the shear bands.

Ages and kinematics of chemically selected, accreted Milky Way halo stars

ABSTRACT We exploit the [Mg/Mn]-[Al/Fe] chemical abundance plane to help identify nearby halo stars in the 14th data release from the APOGEE survey that have been accreted on to the Milky Way. Applying a Gaussian Mixture Model, we find a ‘blob’ of 856 likely accreted stars, with a low disc contamination rate of ∼7 per cent. Cross-matching the sample with the second data release from Gaia gives us access to parallaxes and apparent magnitudes, which place constraints on distances and intrinsic luminosities. Using a Bayesian isochrone pipeline, this enables us to estimate new ages for the accreted stars, with typical uncertainties of ∼20 per cent. This does not account for systematic uncertainties. Our new catalogue is further supplemented with estimates of orbital parameters. The blob stars span [Fe/H] between −2.5 to −0.5, and [Mg/Fe] between −0.1 to 0.5. They constitute ∼30 per cent of the metal-poor ([Fe/H] &amp;lt; −0.8) halo at [Fe/H] ∼ −1.4. Our new ages mainly range between 8 to 13 Gyr, with the oldest stars the metal-poorest, and with the highest [Mg/Fe] abundance. If the blob stars are assumed to belong to a single progenitor, the ages imply that star formation lasted 5 Gyr after which the system merged with our Milky Way around 8 Gyr ago. Dynamical arguments suggest that such a single progenitor would have had a total mass of $\sim 10^{11}\, \mathrm{M}_{\odot }$, similar to that found by other authors using chemical evolution models and simulations.