Miracle-dz/UniFAR-FTUs huggingface dataset:
The (unaccompanied) minor as mobility: the tactics of young African migrants in Italy to contest spatio-temporal control

ABSTRACT This paper critically explores how young migrants in Italy utilise their status as ‘minors’ to construct a ‘better future’ as they transition to adulthood. It draws upon data captured through ethnographic fieldwork with young African men who have made the perilous illegalised journey across the Mediterranean Sea to Italy. I use this data to evidence how these young men engage in unruly mobility within Italy to negotiate the migration regime and resist the immobility, temporal suspense and racialisation of their bodies. These findings contribute to debates in children’s geographies by theorising the multiple temporalities of youth and transnational mobility. More specifically, the paper reveals the inherent contradiction in how mobility represents and is narrated as a resource, and yet can become a trap for young migrants.
Group Polarization in Board Decisions about Strategic Change: Evidence from Chinese Publicly Listed Companies (2008–2018)

ABSTRACT Strategic management scholars have shown increasing interest in explaining strategic change from the perspective of cognitive bias. However, most studies focus on individual cognitive bias but pay little attention to group cognitive bias. This study introduces a typical group cognitive bias (group polarization) to explain strategic change decisions made by the board of directors. Following the theory of group polarization, we argue that, when the average prior strategic change experienced in performance decline by board directors is relatively high (or low), the focal strategic change in performance decline will become even higher (or lower). We further contend that the proportion of female directors and board versus CEO power as the contingencies can mitigate this group polarization effect. Our hypotheses were strongly supported by a longitudinal sample of Chinese publicly listed companies during 2008–2018. The study's framework and findings contribute to the contextualization of social psychology research on group polarization in the study of board's strategic decision-making.
Impact of the COVID-19 pandemic on the nursing students' education in a public university in Colombia

Abstract Objective. To explore the impacts of the COVID-19 pandemic on nursing student education in one public university in Medellin, Colombia. Methods. This descriptive qualitative study used content analysis to address the following questions: (1) How has the COVID-19 pandemic impacted nursing education at the University of Antioquia? (2) What were the most important challenges experienced by nursing students? (3) What was most supportive for the students during the pandemic? and (4) What were the potential opportunities and lessons learned related to nursing education? Data were collected virtually through individual online interviews with 14 undergraduate nursing students and analysed using qualitative content analysis with constant comparisons. Results. Four main categories of findings related to the experience of undergraduate nursing students during the COVID-19 pandemic were identified: (1) transitioning to online learning, (2) managing the digital world, (3) impacts on clinical training, and (4) work-related stressors. Key challenges included home environments that were not conducive to learning, reduced social interactions with peers and faculty, accessing technology required for online education and insufficient preparation for clinical practice. Family members and university-provided resources were important sources of student support. Whereas the pandemic limited opportunities for hands-on clinical training, the shift to online learning allowed for the development of skills related to informational technologies and telehealth. Conclusion. Undergraduate students at the University of Antioquia identified significant barriers to learning during the COVID-19 pandemic restrictions and transition to online learning, as well as new opportunities for the development of digital skills among both students and faculty.
XMM-Newton study of the Draco dwarf spheroidal galaxy

Aims. We present the results of the analysis of five XMM-Newton observations of the Draco dwarf spheroidal galaxy (dSph). The aim of the work is the study of the X-ray population in the field of the Draco dSph. Methods. We classified the sources on the basis of spectral analysis, hardness ratios, X-ray-to-optical flux ratio, X-ray variability, and cross-correlation with available catalogues in X-ray, optical, infrared, and radio wavelengths. Results. We detected 70 X-ray sources in the field of the Draco dSph in the energy range of 0.2−12 keV and classified 18 AGNs, 9 galaxies and galaxy candidates, 6 sources as foreground stars, 4 low-mass X-ray binary candidates, 1 symbiotic star, and 2 binary system candidates. We also identified 9 sources as hard X-ray sources in the field of the galaxy. We derived the X-ray luminosity function of X-ray sources in the Draco dSph in the 2−10 keV and 0.5−2 keV energy bands. Using the X-ray luminosity function in the energy range of 0.5−2 keV, we estimate that ∼10 X-ray sources are objects in the Draco dSph. We have also estimated the dark matter halo mass that would be needed to keep the low-mass X-ray binaries gravitationally bound to the galaxy.
On the Discrepancy of Recent European Ground-Motion Observations and Predictions from Empirical Models: Analysis of KiK-net Accelerometric Data and Point-Sources Stochastic Simulations

Ground-motion amplitudes from recent European earthquakes of moderate magnitudes have been observed to be systematically smaller than the values expected from a number of popular empirical ground-motion prediction equations used for seismic hazard analysis. It has been suggested that these discrepancies are caused by regional variations in seismotectonic character and as a consequence that seismic hazard estimates using these ground-motion models would be too high. In the present article, we explore the hypothesis that the discrepancy can simply be explained by the fact that these models adopt magnitude-independent functional forms (letting Y designate the response spectral acceleration M designate the magnitude, then d log Y / dM is assumed independent of both magnitude and distance). The data collected by the KiK-net array (see the [Data and Resources][1] section) provides a unique opportunity to test this hypothesis and to analyze some of the pitfalls of deriving magnitude-independent functional form models and applying them for predictions of ground motion from smaller events (and vice versa). Borehole rock KiK-net ground-motion data (337 events, 3894 records) have been used to derive empirical ground-motion models with magnitude-independent functional forms for various magnitude ranges. By using these new ground-motion models and stochastic simulations, we discuss the ground-motion distance decays and magnitude effects for ground-motion models obtained with different magnitude range datasets. This analysis clearly indicates that response spectral amplitudes of ground motions from large earthquakes decay slower with distance than those from small earthquakes and confirms that the magnitude scaling of ground motion decreases as earthquake magnitude increases. Using stochastic simulations, we demonstrate that the observed decay in scaling could be a mixture of geometrical decay from extended sources and the fact that response spectral values instead of Fourier spectral values are considered. New ground-motion models (with functional forms including coefficients to model the observed magnitude-dependent scaling and decay rate) have finally been calculated for both surface and borehole site conditions of the analyzed dataset. These models show similar decays for intermediate period or moderate magnitude earthquakes. Our site classifications remove most of the statistical trend of the site effect and suggest that source and path effects could dominate the aleatory variability. [1]: #sec-16
Numerical Study of Internal Flow Structures in a Sweeping Jet Actuator

This study focuses on the generation and interaction of internal flow structures, jet oscillation process, and pressure drop mechanism of a Sweeping Jet Actuator. Timedependent numerical analysis was performed over a range of inlet mass flow rates. The effect of varying inlet mass flow rate on the sweeping jet oscillation frequency was calculated and a strong agreement was found with the experimental measurements. The velocity, temperature and pressure fields are provided. The complex flow field inside the Sweeping Jet Actuator for half an oscillation cycle are presented by velocity magnitude and total pressure contours. Formation of vortices from sharp corners in the actuator core surfaces were observed, and their role in jet oscillation is shown.
Osteogenic Potential of Autologous Dentin Graft Compared with Bovine Xenograft Mixed with Autologous Bone in the Esthetic Zone: Radiographic, Histologic and Immunohistochemical Evaluation

This prospective, randomized, controlled clinical trial reports clinical, radiographic, histologic and immunohistochemical results of autologous dentin graft (ADG) and its comparison with a mixture of bovine xenograft with autologous bone (BX+AB). After tooth extraction in the esthetic zone of maxilla, the alveolar ridge of 20 patients in the test group was augmented with ADG, while 17 patients in the control group received the combination of BX+AB. Cone beam computed tomography (CBCT) was performed before tooth extraction and after 4 months when a total of 22 bone biopsies were harvested and subjected to histological and immunohistochemical analysis. Radiological analysis showed comparable results of bone dimension loss in both groups. Quantitative histologic analysis showed comparable results with no statistically significant differences between the groups. Immunohistochemical staining with TNF-α and BMP-4 antibodies revealed immunopositivity in both groups. A statistically significant difference between the groups was found in the intensity of TNF-α in the area of newly formed bone (p = 0.0003) and around remaining biomaterial particles (p = 0.0027), and in the intensity of BMP-4 in the area around biomaterial particles (p = 0.0001). Overall, ADG showed biocompatibility and achieved successful bone regeneration in the esthetic zone of the maxilla similar to BX+AB.
Theoretical analysis of ultra-lean premixed flames in porous inert media

The structure of stationary adiabatic premixed flames within porous inert media under intense interphase heat transfer is investigated using the asymptotic expansion method. For the pore sizes of interest for combustion in porous inert media, this condition is reached for extremely lean mixtures where lower flame velocities are found. The flame structure is analysed in three distinct regions. In the outer region (the solid-phase diffusion length scale), both phases are in local thermal equilibrium and the problem formulation is reduced to the one-equation model for the energy conservation. In the first inner region (the gas-phase diffusion length scale), there is local thermal non-equilibrium and two equations for the energy conservation are required. In this region, the gas-phase temperature at the flame is limited by the interphase heat transfer. In the second inner region (the reaction length scale), the chemical reaction occurs in a very thin zone where the highest gas-phase temperature is found. The results showed that superadiabatic effects are reduced for leaner mixtures, smaller pore sizes and smaller fuel Lewis numbers. The results also show that there is a minimum superadiabatic temperature for the flame propagation to be possible, which corresponds to the lean flammability limit for the premixed combustion in porous inert media. A parameter that universalizes the leading-order flame properties is identified and discussed.
Fluorescence Lifetime Imaging of Human Sub-RPE Calcification In Vitro Following Chlortetracycline Infusion

We have shown that all sub-retinal pigment epithelial (sub-RPE) deposits examined contain calcium phosphate minerals: hydroxyapatite (HAP), whitlockite (Wht), or both. These typically take the form of ca. 1 μm diameter spherules or >10 μm nodules and appear to be involved in the development and progression of age-related macular degeneration (AMD). Thus, these minerals may serve as useful biomarkers the for early detection and monitoring of sub-RPE changes in AMD. We demonstrated that HAP deposits could be imaged in vitro by fluorescence lifetime imaging microscopy (FLIM) in flat-mounted retinas using legacy tetracycline antibiotics as selective sensors for HAP. As the contrast on a FLIM image is based on the difference in fluorescence lifetime and not intensity of the tetracycline-stained HAP, distinguishing tissue autofluorescence from the background is significantly improved. The focus of the present pilot study was to assess whether vascular perfusion of the well tolerated and characterized chlortetracycline (widely used as an orally bioavailable antibiotic) can fluorescently label retinal HAP using human cadavers. We found that the tetracycline delivered through the peripheral circulation can indeed selectively label sub-RPE deposits opening the possibility for its use for ophthalmic monitoring of a range of diseases in which deposit formation is reported, such as AMD and Alzheimer disease (AD).
The Generalized-α Scheme as a Linear Multistep Integrator: Toward a General Mechatronic Simulator

This paper presents a consistent formulation of the generalized-a time integration scheme for mechanical and mechatronic systems. The algorithm can deal with a nonconstant mass matrix, controller dynamics, and kinematic constraints. The theoretical background relies on the analogy with linear multistep formulas, which leads to elegant results related to consistency, order conditions for constant and variable step-size methods, as well as global convergence. Those results are illustrated for a controlled spring-mass system, and the method is also applied for the simulation of a vehicle semi-active suspension.
Extratropical fronts in the lower troposphere–global perspectives obtained from two automated methods

In this study two commonly used automated methods to detect atmospheric fronts in the lower troposphere are compared in various synoptic situations. The first method is a thermal approach, relying on the gradient of equivalent potential temperature (TH), while the second method is based on temporal changes in the 10 m wind (WND). For a comprehensive objective comparison of the outputs of these methods of frontal identification, both schemes are firstly applied to an idealised strong baroclinic wave simulation in the absence of topography. Then, two case‐studies (one in the Northern Hemisphere (NH) and one in the Southern Hemisphere (SH)) were conducted to contrast fronts detected by the methods. Finally, we obtain global winter and summer frontal occurrence climatologies (derived from ERA‐Interim for 1979–2012) and compare the structure of these. TH is able to identify cold and warm fronts in strong baroclinic cases that are in good agreement with manual analyses. WND is particularly suited for the detection of strongly elongated, meridionally oriented moving fronts, but has very limited ability to identify zonally oriented warm fronts. We note that the areas of the main TH frontal activity are shifted equatorwards compared to the WND patterns and are located upstream of regions of main WND front activity. The number of WND fronts in the NH shows more interseasonal variations than TH fronts, decreasing by more than 50% from winter to summer. In the SH there is a weaker seasonal variation of the number of observed WND fronts, however TH front activity reduces from summer (DJF) to winter (JJA). The main motivation is to give an overview of the performance of these methods, such that researchers can choose the appropriate one for their particular interest.
The evolution of highly compact binary stellar systems

A new theoretical treatment of the evolution of highly compact binary systems is presented. The evolution is calculated until almost the entire mass of the secondary has been transferred to the primary or lost from the system. It is assumed that gravitational radiation from the system is the cause of mass transfer. It is found that the structure of the mass-losing star can be approximated by an n = 3/2 polytrope, and as a result a relatively large number of different cases can be explored and some general conclusions drawn. An explanation is found for the existence of a cutoff in the orbital period distribution among the cataclysmic variables and light is shed upon the possible generic relationships among cataclysmic variables, the low-mass X-ray binaries, and the spectrally soft transient X-ray sources.
An Efficient XFEM Approximation of Darcy Flows in Arbitrarily Fractured Porous Media

Subsurface flows are influenced by the presence of faults and large fractures which act as preferential paths or barriers for the flow. In literature models were proposed to handle fractures in a porous medium as objects of codimension 1. In this work we consider the case of a network of intersecting fractures, with the aim of deriving physically consistent and effective interface conditions to impose at the intersection between fractures. This new model accounts for the angle between fractures at the intersections and allows for jumps of pressure across the intersection. This latter property permits to describe more accurately the flow when fractures are characterised by different properties, than other models that impose pressure continuity. The main mathematical properties of the model, derived in the two-dimensional setting, are analysed. As concerns the numerical discretization we allow the grids of the fractures to be independent, thus in general non-matching at the intersection, by means of the Extended Finite Element Method (XFEM), to increase the flexibility of the method in the case of complex geometries characterized by a high number of fractures.
Cattle manure solarization with transparent plastic to pathogens control

The objective of this work was to evaluate the effect of plastic cover without albedo for solarizing cattle manure in order to eliminate pathogens and to obtain a safe organic fertilizer. The treatments consisted of piles of manure with single and double cover and a control without cover. The experimental design was a randomized blocks with factorial arrangement and three replications and separation of means by Tukey test (P=0.05) analyzed with SAS statistical software. During 20 days the temperatures were registered hourly in each pile at depths of 30 and 60 cm. Five microbiological analyzes were realized in order to detect Escherichia coli and Salmonella spp in each treatment. The results showed a greater homogeneity of temperature in the piles with double covered in the vertical plane, registering 62 oC at 30 cm and 60 oC at 90 cm of depth; the temperature with single cover was of 61.5 oC at 30 cm and 58 oC at 90 cm of depth; the control showed temperature of 58 oC at 30 cm and 47 °C at 90 cm. The microbiological results before the solarization showed the presence of Escherichia coli and Salmonella spp. , but after solarization process these pathogens were detected only in the control, with a minimum effective time of solarization of 21 days. The solarization of cattle manure in piles with single and double cover is an alternative to produce an organic and innocuous compost to use it in agriculture.
Thermophysical and mechanical properties of LaB6 and CeB6 synthesized through spark plasma sintering

ABSTRACT Following the Fukushima Daiichi nuclear power plant accident in 2011, the development of accident tolerant fuels (ATFs) has become an integral part of the promotion of nuclear safety. Of the many design criteria, a high thermal conductivity reduces a fuel pellet’s peak temperature and radial temperature gradient. Although various uranium borides such as UB2 and UB4 are promising ATFs that have high-temperature stability, high uranium density, and good thermal conductivity, little is known about UB6, as it has yet to be fabricated under normal conditions. As a metal hexaboride, UB6 may have excellent electrical conductivity, likely giving it a much higher thermal conductivity than that of UO2. In this work, we investigate the thermophysical and mechanical properties of non-radioactive LaB6 and CeB6 to estimate the potential properties of UB6, as it has yet to be successfully fabricated. The thermophysical properties of UB6 are compared with those of UO2, UB2, and UB4 to help clarify whether future attempts at fabricating UB6 under high pressure or with other dopants are worthwhile for the development of ATFs. Graphical abstract
The Role of the Axiomatic Method

Ever since its importance to the development of mathematical theory has been realized, much has been written on the axiomatic method. However, except for the work of a few pioneers of the early part of the present century, such as Skolem and Tarski, most of this writing has been done during the past 20 years, roughly speaking. It took the mathematical world a long time to realize the potentialities of the method-and, we should add, to recognize its limitations -and it is undoubtedly true that even today some eminent mathematicians deplore its widespread use. The point of view taken by both Poincare [10] and H. Weyl still survives. Although recognizing the accomplishrnents of the method, Weyl felt that its fertility was "approaching exhaustion" [15]. He made a firm plea for a return to problems of "mathematical substance" wAThich, he maintained, form the basis for the concepts subsequently cast in axiomatic form. Both Poincare and Weyl were intuitionists of sorts; they believed that mathematics can not be reduced to axiomatic form without sacrificing something of its true nature. They did not deny that axiomatics is a legitimate tool, but only as a device for giving precision to already created mathematical entities-a kind of classifying or cataloging function, much as the present-day intuitionist considers it to be. It therefore seems timely to reappraise the role of the method, particularly in view of recent developments in mathematical logic; and to gain proper perspective for the task, it appears that we should begin with a short review of its evolution. In studying the evolution of mathematical concepts, I have found it convenient to distinguish between those cultural stresses which influence the development of concepts, according to their "hereditary" and their environmental aspects. For example, the inception of most early mathematics, such as arithmetic, and geometry in its primitive forms, was due to environmental forces; but the axiomatic mnethod occupies a unique position in that it appears to have owed its inception chiefly or even entirely to hereditary stresses. In other words, the factors which forced its creation were based on internal rather than external needs. Of course, because of the dearth of knowledge concerning early Greek developments, one cannot be absolutely positive about this. However, most historians seem to agree that crises, attendant upon the attempts to cope with paradoxes such as those of Zeno, compelled the formulation of a basic set of principles upon which to erect the geometrical edifice. The introduction of the method carried with it a tacit acceptance of certain types of logical reasoning; thus logical deduction was applied to mathematics for the first time. Accordingly, it seems reasonable to regard as the chief role played by the axiomatic method in Greek mathematics, that of providing a consistent foundation. In considering this role, we should note two aspects of the method: (1) The manner in which logic was brought into mathematics; indeed, both the motive (namely, to achieve a consistent system) and the methodological aspect (logical