Miracle-dz/UniFAR-FTUs huggingface dataset:
Simulations of the Small-Scale Turbulent Dynamo

We report the results of an extensive numerical study of the small-scale turbulent dynamo. The primary focus is on the case of large magnetic Prandtl numbers Prm, which is relevant for hot low-density astrophysical plasmas. A Prm parameter scan is given for the model case of viscosity-dominated (low Reynolds number) turbulence. We concentrate on three topics: magnetic energy spectra and saturation levels, the structure of the magnetic field lines, and intermittency of the field strength distribution. The main results are as follows: (1) the folded structure of the field (direction reversals at the resistive scale, field lines curved at the scale of the flow) persists from the kinematic to the nonlinear regime; (2) the field distribution is self-similar and appears to be lognormal during the kinematic regime and exponential in the saturated state; and (3) the bulk of the magnetic energy is at the resistive scale in the kinematic regime and remains there after saturation, although the magnetic energy spectrum becomes much shallower. We propose an analytical model of saturation based on the idea of partial two-dimensionalization of the velocity gradients with respect to the local direction of the magnetic folds. The model-predicted saturated spectra are in excellent agreement with numerical results. Comparisons with large-Re, moderate-Prm runs are carried out to confirm the relevance of these results and to test heuristic scenarios of dynamo saturation. New features at large Re are elongation of the folds in the nonlinear regime from the viscous scale to the box scale and the presence of an intermediate nonlinear stage of slower than exponential magnetic energy growth accompanied by an increase of the resistive scale and partial suppression of the kinetic energy spectrum in the inertial range. Numerical results for the saturated state do not support scale-by-scale equipartition between magnetic and kinetic energies, with a definite excess of magnetic energy at small scales. A physical picture of the saturated state is proposed.
Comparison of Gravitational Waves from Central Engines of Gamma-Ray Bursts: Neutrino-dominated Accretion Flows, Blandford–Znajek Mechanisms, and Millisecond Magnetars

Neutrino-dominated accretion flow (NDAF) around a rotating stellar-mass black hole (BH) is one of the plausible candidates for the central engines of gamma-ray bursts (GRBs). Because the time-variant and anisotropic emission of neutrinos from NDAFs leads to GRB variability, NDAFs can be regarded as the sources of strong gravitational waves (GWs). We calculate the dependences of the GW strains on both the BH spin and the accretion rate. We demonstrate that, for typical GRBs with either a single pulse or multiple pulses, the GWs from NDAFs might be detected at a distance of ∼100 kpc/∼1 Mpc by the advanced LIGO/Einstein Telescope with a typical frequency of ∼ 10 – 100 Hz . Besides NDAFs, the other two competitive candidates for the GRB central engine are the Blandford–Znajek (BZ) mechanism and millisecond magnetars. We explore the GW signals from these two as well, and compare the corresponding results with NDAFs’. We find that for a certain GRB, the possible detected distance from NDAFs is about two orders of magnitude higher than that from the BZ mechanism, but at least two orders of magnitude lower than that from magnetars. The typical GW frequency for the BZ mechanism is the same as that of NDAFs, ∼ 10 – 100 Hz , while the typical frequency for magnetars is ∼2000 Hz. Therefore, the GWs released by the central engines of adjacent GRBs might be used to determine whether there is an NDAF, a BZ jet, or a magnetar in the GRB center.
The Dynamics of Truncated Black Hole Accretion Disks. II. Magnetohydrodynamic Case

We study a truncated accretion disk using a well-resolved, semi-global magnetohydrodynamic simulation that is evolved for many dynamical times (6096 inner disk orbits). The spectral properties of hard-state black hole binary systems and low-luminosity active galactic nuclei are regularly attributed to truncated accretion disks, but a detailed understanding of the flow dynamics is lacking. In these systems the truncation is expected to arise through thermal instability driven by sharp changes in the radiative efficiency. We emulate this behavior using a simple bistable cooling function with efficient and inefficient branches. The accretion flow takes on an arrangement where a “transition zone” exists in between hot gas in the innermost regions and a cold, Shakura & Sunyaev thin disk at larger radii. The thin disk is embedded in an atmosphere of hot gas that is fed by a gentle outflow originating from the transition zone. Despite the presence of hot gas in the inner disk, accretion is efficient. Our analysis focuses on the details of the angular momentum transport, energetics, and magnetic field properties. We find that the magnetic dynamo is suppressed in the hot, truncated inner region of the disk which lowers the effective α-parameter by 65%.
Searching for dark matter with future cosmic positron experiments

Dark matter particles annihilating in the Galactic halo can provide a flux of positrons potentially observable in upcoming experiments, such as PAMELA and AMS-02. We discuss the spectral features which may be associated with dark matter annihilation in the positron spectrum and assess the prospects for observing such features in future experiments. Although we focus on some specific dark matter candidates, neutralinos and Kaluza-Klein states, we carry out our study in a model independent fashion.
Identifying the presence of context and item-writing flaws in practice items: The case of Turkish mathematics textbooks

This study seeks to ascertain the degree to which context-based items are offered in Turkish mathematics textbooks as well as the quality of the items in terms of item writing guidelines, whether or not they are given as traditional or context-based. A qualitative research approach is used in this study. The eighth-grade mathematics textbook used in public schools and a textbook used in certain private school chains constitute its sample. The practice items (i.e, exercises without solutions given) included in the textbooks were analyzed by performing document analysis. The results revealed that both textbooks contain several flawed items in terms of item writing rules, as well as having mainly non-contextual items.
Extracting contact effects in organic field-effect transistors

— Contact resistances between organic semiconductors and metal electrodes have been shown to play a dominant role in electronic charge injection properties of organic field effect transistors. These effects are more prevalent in short channel length devices and therefore should not be ignored when examining intrinsic properties such as the mobility and its dependence on temperature or gate voltage. Here we outline a general procedure to extract contact current-voltage characteristics and the true channel mobility from the transport characteristics in bottom contact poly (3-hexylthiophene) field effect transistors, for both ohmic and nonlinear charge injection, over a broad range of temperatures and gate voltages. Distinguishing between the contact and channel contributions in bottom contact OFETs is an important step toward improved understanding and modeling of these devices.
DESCQA: An Automated Validation Framework for Synthetic Sky Catalogs

The use of high-quality simulated sky catalogs is essential for the success of cosmological surveys. The catalogs have diverse applications, such as investigating signatures of fundamental physics in cosmological observables, understanding the effect of systematic uncertainties on measured signals and testing mitigation strategies for reducing these uncertainties, aiding analysis pipeline development and testing, and survey strategy optimization. The list of applications is growing with improvements in the quality of the catalogs and the details that they can provide. Given the importance of simulated catalogs, it is critical to provide rigorous validation protocols that enable both catalog providers and users to assess the quality of the catalogs in a straightforward and comprehensive way. For this purpose, we have developed the DESCQA framework for the Large Synoptic Survey Telescope Dark Energy Science Collaboration as well as for the broader community. The goal of DESCQA is to enable the inspection, validation, and comparison of an inhomogeneous set of synthetic catalogs via the provision of a common interface within an automated framework. In this paper, we present the design concept and first implementation of DESCQA. In order to establish and demonstrate its full functionality we use a set of interim catalogs and validation tests. We highlight several important aspects, both technical and scientific, that require thoughtful consideration when designing a validation framework, including validation metrics and how these metrics impose requirements on the synthetic sky catalogs.
Contemporary Cultural Trade of Lion Body Parts

Simple Summary Cultural and traditional practices play a substantial but generally underestimated and poorly understood role in the use of wildlife. While the trade in traditional medicine or ‘muthi’ is a dynamic network of stakeholders, for this study we focused on commercial traders and traditional healers. We investigated various aspects of trade in lion parts through a semi-structured questionnaire, focusing on cultural applications, demand, trade dynamics, sources, and supply. In order to enhance our understanding of the challenges of product access and equitable use, we explored various motivations behind use (e.g., cultural and livelihood), perceptions of sustainability, and welcomed any participant-proposed initiatives to conserve lions. Our results indicated that lions were used symbolically for their power, strength, and nobility, and in rituals of healer training. Most participants believed lion populations to be declining and offered solutions to maintain lion product supplies. We highlight the importance of understanding cultural influence in the use of wildlife to ensure that all stakeholder voices are included in the development and implementation of conservation initiatives. Abstract Trade in lion parts associated with cultural and traditional use is poorly understood. Here we sought to better understand the role and use of lion body parts in the commercial traditional medicine (muthi) trade of South Africa. In 2019 we conducted a semi-structured questionnaire survey of muthi traders (n = 10) and traditional healers (n = 20) which explored the significance and symbolism of lions, traded parts and preferences, sources and supply of lion parts, and perceived sustainability of lion derivatives in the South African muthi trade. Our results suggest a cultural importance of lion associated with the umndawu ancestral spirit in particular, as well as in the training and practice of cultural–spiritual healers. Lion paws and parts thereof were most frequently reported as sold by traders and demanded by healers, correlating with recent trends in body-part removals from lion mortalities. Respondents indicated that lion parts were obtained from a variety of sources including wild lion populations in neighbouring countries and captive-breeding farms. Our findings are discussed relative to current concerns in lion conservation and highlight a need for further understanding of the traditional medicine complex, the influence that ancestral spirits have on lion body-part trade, and increased engagement with traditional medicine stakeholders.
Sensitivity Analysis in Parametrized Convex Vector Optimization

This paper provides some results concerning sensitivity analysis in parametrized convex vector optimization. We consider three types of perturbation maps (i.e., perturbation map, proper perturbation map, and weak perturbation map) according to three kinds of solution concepts (i.e., minimality, proper minimality, and weak minimality with respect to a fixed ordering cone) for a vector optimization problem. As for general vector optimization, authors have already established the behavior of the above three types of perturbation maps by using the concept of contingent derivatives for set-valued maps in finite dimensional Euclidean spaces. In this paper we concentrate on convex vector optimization and provide quantitative properties of the perturbation maps under some convexity assumptions. Namely, we investigate the relationships between the contingent derivatives of the perturbation maps and those of the feasible set map in the objective space.
Comparison of Machine Learning Techniques for Condition Assessment of Sewer Network

Assessment of sewer condition is one of the critical steps in asset management and support investment decisions; therefore, condition assessment models with high accuracy are important that can help utility managers and other authorities correctly assess the current condition of the sewage network and effectively initiate maintenance and rehabilitation strategies. The main objective of this research is to assess the potential application of machine learning (ML) algorithms for predicting the condition of sewer pipes with a case study in Ålesund city, Norway. Nine physical factors (i.e., age, diameter, depth, slope, length, pipe type, material, pipe form, and connection type) and ten environmental factors (i.e., rainfall, geology, landslide area, building area, population, land cover, groundwater, traffic volume, distance to road, and soil type) were used to assess the sewer conditions employing seventeen ML models. After processing the sewer inspections, 1159 of 1449 individual pipelines were used to train the sewer condition model. The performance of ML models was validated using the 290 remaining inspected sewer pipes. The area under the Receiver Operating Characteristic (AUC-ROC) curve and accuracy (ACC) showed that the Random Forest (AUC-ROC = 77.6% and ACC = 78.3%) is a sensitive model for predicting the condition of sewer pipes in the study area. Based on the Random Forest model, maps of predicted conditions of sewers were generated that may be useful for utilities and water managers to establish future sewer system maintenance strategies.
Crystalline phases in chiral ferromagnets : Destabilization of helical order

In chiral ferromagnets, weak spin-orbit interactions twist the ferromagnetic order into spirals, leading to helical order. We investigate an extended Ginzburg-Landau theory of such systems where the helical order is destabilized in favor of crystalline phases. These crystalline phases are based on periodic arrangements of double-twist cylinders and are strongly reminiscent of blue phases in liquid crystals. We discuss the relevance of such blue phases for the phase diagram of the chiral ferromagnet MnSi.
Australia’s fiscal surplus: Child of a credit and real estate boom

For several years leading up to the 2008 financial crisis, Australia registered a public surplus, and this was generally interpreted as the result of responsible fiscal policy. However, since the outbreak of that crisis, no such fiscal balance has again been attained, giving rise to a range of explanations from the political incapacity of governments to the weak economic behaviour characterising the post-crisis era. Noteworthy in any case is that analysts have failed to cite the importance of a factor that was key to reaching pre-crisis surpluses: the vertiginous growth of private debt. This work argues that it was precisely the intense granting of bank loans and consequent increased demand from the private sector that boosted economic activity and led to the generation of public income sufficient to feed the fiscal surpluses of that period. Indeed, according to the proposals of Wynne Godley, this would have been the only way to register a public surplus in a context of current account deficits, typical of the Australian economy. This paper considers whether Australian private debt played a significant role in achieving fiscal surplus by way of a review of the Australian real estate boom and public accounts from the 1990s onward, also estimating an econometric model of autoregressive vectors to explore the link between these two variables. The results obtained appear to corroborate the hypothesis: severe private borrowing contributed to Australia’s fiscal surpluses. This finding has significant implications for budgetary policy. JEL Codes: E51, E62, H62
Validation approaches for satellite-based PM2.5 estimation: Assessment and a new approach

Satellite-derived aerosol optical depth (AOD) has been increasingly employed for the estimation of ground-level PM2.5, which is often achieved by modeling the relationship between AOD and PM2.5. To evaluate the accuracy of PM2.5 estimation, the cross-validation (CV) technique has been widely used. There have been several CV-based validation approaches applied for the AOD-PM2.5 models. However, the applicable conditions of these validation approaches still remain unclear. Additionally, is there space to develop better validation approaches for the AOD-PM2.5 models? The contributions of this study can be summarized as two aspects. Firstly, we comprehensively analyze and assess the existing validation approaches, and give the suggestions for applicable conditions of them. Then, the existing validation approaches do not take the distance to monitoring station into consideration. A new validation approach considering the distance to monitoring station is proposed in this study. Among the existing validation approaches, the sample-based CV is used to reflect the overall prediction ability; the site-based CV and the region-based CV have the potentials to evaluate spatial prediction performance; the time-based CV and the historical validation are capable of evaluating temporal prediction accuracy. In addition, the validation results indicate that the proposed validation approach has shown great potentials to better evaluate the accuracy of PM2.5 estimation. This study provides application implications and new perspectives for the validation of AOD-PM2.5 models.
PSYCHOMETRIC PROPERTIES OF THE STATE-TRAIT ANXIETY INVENTORY-TRAIT (STAI-T) IN ARGENTINIAN ADOLESCENTS

The aim of the present study was to analyze the psychometric properties of the State-Trait Anxiety Inventory- Trait dimension (STAI-T), Form X. A total of 798 Argentinian adolescents aged between 12 and 18 years (M = 14; SD = 1.31) participated in this study. The psychometric properties of the instrument were analyzed from the contributions of the Rasch model, which allowed us to assess the measurement model fit, response threshold order, item and person fit, local dependence, differential item functioning (DIF), reliability, targeting, and unidimensionality. The results showed that the STAI-T, anxiety-absent items, and anxiety-present items presented values close to the expected ones for item and person fit, ordered response categories, appropriate reliability levels, and adequate targeting. Only in anxiety-absent items, it was possible to verify compliance with unidimensionality, whereas in anxiety-present items there were items with local dependence or showing DIF. The present study provides empirical evidence based on a rigorous measurement model that allows corroborating the validity of the scale to assess anxiety in Argentinian adolescents.
An Interacting Galaxy Pair at the Origin of a Light Echo

In a low-density region of the Shapley supercluster we identified an interacting galaxy pair at redshift z = 0.04865 in which the Seyfert 2 nucleus of the main galaxy (ShaSS 073) is exciting an extended emission line region (EELR, ∼170 kpc2) in the disk of the less massive companion (ShaSS 622). New integral-field spectroscopy and the multiband data set, spanning from far-ultraviolet to far-infrared and radio wavelengths, allowed us to obtain a detailed description of the ShaSS 622–073 system. The gas kinematics shows hints of interaction, although the overall velocity field shows a quite regular rotation in both galaxies, thus suggesting that we are observing their first encounter as confirmed by the estimated distance of 21 kpc between the two galaxy centers. The detected active galactic nucleus (AGN) outflow and the geometry of the EELR in ShaSS 622 support the presence of a hollow bicone structure. The status and sources of the ionization across the whole system have been analyzed through photoionization models and a Bayesian approach that prove a clear connection between the AGN and the EELR. The luminosity of the AGN ( erg s−1) is a factor of 20 lower than the power needed to excite the gas in the EELR (4.6 × 1045 erg s−1), indicating a dramatic fading of the AGN in the past 3 × 104 yr. ShaSS 073–622 provides all the ingredients listed in the recipe of a light echo where a highly-ionized region maintains memory of a preceding more energetic phase of a now-faded AGN. This is the first case of a light echo observed between two galaxies.
Realizing Thermoelectric and Thermistor Bi-functionalities via Triggering Electron Correlations with Lattice-dipole

Establishing strong electron-correlations not only shed lights on overcoming the trade-off limitations for optimizing thermoelectric materials, but can also introduce new functionalities that extend the vision of conventional thermoelectric applications. Here, we demonstrate that the high thermoelectric and thermistor functionalities coexist in lattice distorted SrNbxTi1-xO3 films with electron correlations between carriers and ordering aligned lattice dipoles. As-grown SrNbxTi1-xO3/SrTiO3 with effectively preserved interfacial strains exhibits cross-plane charge ordering and orbital anisotropy, as indicated by the polarization dependent near edge X-ray absorption fine structures. The resultant coulomb-correlations regulate the carrier transport and enhance the Seebeck coefficient more independently via enlarging the system vibration entropy. As-achieved maximum thermoelectric power factor exceeds 100 uWcm-1K-2 measured in the bulk performance of SrNb0.2Ti0. 8O3 (2.2 um)/SrTiO3 (100 um), which is comparable to the best thermoelectric materials for low temperature applications. In addition, the strong temperature dependence of the carrier scattering aroused by the lattice dipoles introduces a positive temperature dependent thermistor transportation behavior with large temperature coefficient of resistance ranging from 30 to 300 K, which is rarely seen in conventional thermistors. Combining both functionalities largely extend the horizon in exploring new Joule sensors for detection of temperature and thermal perturbations across a broad temperature range.
Chandra/HETGS Observations of the Capella System: The Primary as a Dominating X-Ray Source

Using the Chandra/High Energy Transmission Grating Spectrometer (HETGS), we have detected the Doppler motion of Capella's X-ray emission lines in the 6-25 Å wave band. The observed motion follows the expected orbital motion of Capella's primary. This finding implies that the primary G8 III star, not the secondary G1 III star in the Hertzsprung gap, has been the dominant source of hot 106.8-107 K plasma at least in the last 6 years. In addition, the results demonstrate the long-term stability of the HETGS, and they demonstrate small uncertainties of 25 and 33 km s-1 in the velocity determination with the High and Medium Energy Gratings (HEG and MEG), respectively.