FOSTRAD : An advanced open source tool for re-entry analysis

This work responds to the need of modeling the atmospheric re-entry of space debris, satellites, and spacecraft quickly, efficiently and with a reasonable reliability. The Free Open Source Tool for Re-entry of Asteroids and Debris (FOSTRAD) is a simulation suite that allows for the estimation of aerodynamics and aerothermodynamics of an entry object in a continuum or rarefied hypersonic flow by employing the local panel formulation. In this paper, the work done to integrate the tool within a comprehensive framework allowing the simulation of complex geometries using a mesh handler module, a 3DOF trajectory propagator, and a surrogate model generation function, is presented. In addition, a synchronous coupling with a 1D thermal ablation code has been implemented and tested. The mesh module allows operations such as surface local radius computation, surface facets visibility identification, and objects geometrical evolution due to the burn-up during the re-entry. In the continuum regime, the simplified aerothermodynamics are computed using a local radius formulation, while the tool employs a flat-plate based approach in the free molecular regime. A generalized nose radius-based bridging model has been introduced for the rarefied transitional regime. The tests have demonstrated that applying a local radius formulation along with the radius-based bridging model greatly improves the accuracy of re-entry heat-flux estimations. The integrated framework has been tested on two different examples of atmospheric re-entries: the ESA Intermediate Experimental Vehicle (IXV) trajectory optimization and the Stardust sample return capsule Thermal Protection System (TPS) burn-up recession; and the coupling between FOSTRAD and the thermal ablation code allowed to study a step-by-step trajectory evolution of Stardust TPS. The obtained results show good agreement with the literature

Can Temptation Explain Housing Choices over the Life Cycle?

We use individual life-history data from twelve European countries, and duration analysis that controls for unobserved heterogeneity, to investigate whether observed patterns of investment in illiquid assets and housing are consistent with predictions based on \u201ctemptation preferences\u201d. A motivating model takes into account the standard motives for saving, but also recognizes that illiquid financial assets and housing may be used by individuals who find it hard to control the temptation linked to abundant cash on hand. Even controlling for many possible motives for purchasing housing, and for unobserved heterogeneity, a large fraction of individuals become significantly more likely to buy housing after investing in illiquid assets; this finding is consistent with the predictions of the model

University students' discourse about irreducible polynomials

The purpose of this paper is to analyse, following Sfard’s theoretical framework, the students’ discourse about irreducible polynomials in order to understand their difficulties. Through the students’ explanations, given during the interviews conducted after carrying out the questionnaire, it is possible to study which processes were triggered by them to solve the task. In particular, we focused on the concept of the irreducible polynomials and the link between the roots of the polynomial and its reducibility in university students

The Risks of Phosphate Enemas in Toddlers: A Life-Threatening Unawareness

Background: While oral laxatives represent the first-line treatment of fecal impaction, enemas are frequently used in clinical practice in pediatric emergency departments (PEDs) and by family pediatricians (FPs). Objectives: Phosphate-containing enemas (PcEs) are commonly employed, even causing the risk of rare but lethal toxicity. We investigated pediatricians' awareness of PcE risks. Methods: We conducted an online survey by sending a multiple-choice questionnaire to the referents of 51 PEDs and 101 FPs. We collected and compared the answers with recommendations reported by the Italian Drug Agency (AIFA) and the available literature about PcE administration. Results: Of the institutions and pediatricians receiving the questionnaire, 23 PEDs (45%) and 63 FP (62.3%) participated in the survey. Of PEDs, 95% and 33.0% of FPs treated fecal impaction with PcE. Moreover, 54% of PEDs and 86.0% of FPs did not provide treatment according to the AIFA recommendations for the daily dose. Conclusions: This study shows limited pediatricians' awareness of the potential risks related to PcE

Regeneration of articular cartilage: Scaffold used in orthopedic surgery. A short handbook of available products for regenerative joints surgery

Introduction: Restoring defects of load-bearing connective tissues such as articular cartilage resulting from traumas, degenerative or age-related diseases remains a significant clinical challenge for clinicians due to the limited inherent repair capacity of articular cartilage. Tissue engineering has emerged as a potential alternative to the traditional surgical techniques, as it can be effectively used to regenerate bone, cartilage and the bone-cartilage interface. Several scaffold strategies have been developed and evaluated for osteochondral defect repair. Materials and methods: The classes of polymers (scaffold-based proteins, scaffold-base polysaccharides and synthetic scaffolds) and Hydrogels have been reviewed trough literature and market search. The study focused on their respective properties and analyzed advantages and disadvantages of each of them. Discussion: Clinical studies demonstrated improved cartilage regeneration thanks to the implantation of biomaterials after bone marrow stimulation. New cartilage can be engineered in vivo by transplanting chondrocytes seeded into a three-dimensional scaffold and this novel scaffold has mechanical properties that can be comparable to native cartilage and could be used to repair large osteochondral joints defects. Anyway, there is still space for improvement regarding clinical outcome and tissue quality

Analysis of the human Y-chromosome haplogroup Q characterizes ancient population movements in Eurasia and the Americas

Background: Recent genome studies of modern and ancient samples have proposed that Native Americans derive from a subset of the Eurasian gene pool carried to America by an ancestral Beringian population, from which two well-differentiated components originated and subsequently mixed in different proportion during their spread in the Americas. To assess the timing, places of origin and extent of admixture between these components, we performed an analysis of the Y-chromosome haplogroup Q, which is the only Pan-American haplogroup and accounts for virtually all Native American Y chromosomes in Mesoamerica and South America. Results: Our analyses of 1.5 Mb of 152 Y chromosomes, 34 re-sequenced in this work, support a "coastal and inland routes scenario" for the first entrance of modern humans in North America. We show a major phase of male population growth in the Americas after 15 thousand years ago (kya), followed by a period of constant population size from 8 to 3 kya, after which a secondary sign of growth was registered. The estimated dates of the first expansion in Mesoamerica and the Isthmo-Colombian Area, mainly revealed by haplogroup Q-Z780, suggest an entrance in South America prior to 15 kya. During the global constant population size phase, local South American hints of growth were registered by different Q-M848 sub-clades. These expansion events, which started during the Holocene with the improvement of climatic conditions, can be ascribed to multiple cultural changes rather than a steady population growth and a single cohesive culture diffusion as it occurred in Europe. Conclusions: We established and dated a detailed haplogroup Q phylogeny that provides new insights into the geographic distribution of its Eurasian and American branches in modern and ancient samples

Bootstrapping an Italian VerbNet: data-driven analysis of verb alternations

The goal of this paper is to propose a classification of the syntactic alternations admitted by the most frequent Italian verbs. The data-driven two-steps procedure exploited and the structure of the identified classes of alternations are presented in depth and discussed. Even if this classification has been developed with a practical application in mind, namely the semi-automatic building of a VerbNet-like lexicon for Italian verbs, partly following the methodology proposed in the context of the VerbNet project, its availability may have a positive impact on several related research topics and Natural Language Processing tasks

A case study for spacegate point-to-point transportation: Evaluation of a reference end-to-end mission operations and assessment of the associated safety aspects

The ALTEC-conducted Spacegate feasibility study addresses the opportunities offered by the sub-orbital flight with special emphasis to future generation transportation. Pursuing the same systemic methodology of the initial Spacegate definition activities, this paper focuses on some specific aspects of suborbital operations and outlines a top level end-to-end operating cycle for a reference suborbital mission spanning from pre-flight, to flight, re-entry and post landing operations and associated Ground Segment. Special focus is given to identification of suitable locations in Italy for suborbital operations, and to liftoff and re-entry phases; the results of specific simulations are also reported, showing some lift off options and the feasibility of the spiral shaped descent maneuver that improves the pilot controllability of the vehicle during the re-entry phase. Further, this paper outlines within the selected reference mission, the main safety aspects considered as driving factors in planning and implementing future generation transportation; areas such as launch/landing range and relevant risk management/mitigation policies, as well as selection of safety driving criteria in the definition of trajectories and space transition corridors, and capabilities to monitor the vehicle ascent and re-entry will be assessed. Safety regulations will also be evaluated to protect launch range, drive spaceport site selection and consequently the ability of the spaceport to accommodate large numbers of passengers and participants, as well as a number of simultaneous operations such as training, vehicle integration tasks, and passenger preparation for flight. For human flight in general, and in particular for commercial point to point activities at this early stage, it is vital to minimize risk since a fatal accident at the very beginning of flights will put the entire business in jeopardy. The regulatory challenges with regards to safety will also be outlined in this paper, related to executing Spacegate activities in Europe and collaborations with the involved Agencies in the USA and Europe (FAA, ENAC, ENAV, SESAR, EASA) will be explored; in particular, some initiatives have already been started, that include active ALTEC participation to the IAASS Space Safety Technical Committee (SSTC) that was created to contribute to the advancement of the Safety in the area of the "Commercial Suborbital Flight"

Development of an inducible mouse model of iRFP713 to track recombinase activity and tumour development in vivo

While the use of bioluminescent proteins for molecular imaging is a powerful technology to further our understanding of complex processes, fluorescent labeling with visible light fluorescent proteins such as GFP and RFP suffers from poor tissue penetration and high background autofluorescence. To overcome these limitations, we generated an inducible knock-in mouse model of iRFP713. This model was used to assess Cre activity in a Rosa Cre-ER background and quantify Cre activity upon different tamoxifen treatments in several organs. We also show that iRFP can be readily detected in 3D organoid cultures, FACS analysis and in vivo tumour models. Taken together we demonstrate that iRFP713 is a progressive step in in vivo imaging and analysis that widens the optical imaging window to the near-infrared spectrum, thereby allowing deeper tissue penetration, quicker image acquisition without the need to inject substrates and a better signal to background ratio in genetically engineered mouse models (GEMMs)