54 research outputs found

    Calculations for Extended Thermodynamics of dense gases up to whatever order and with all the symmetries

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    The 14 moments model for dense gases, introduced in the last years by Arima, Taniguchi Ruggeri, Sugiyama, is here considered. They have found the closure of the balance equations up to second order with respect to equilibrium; here the closure is found up to whatever order with respect to equilibrium, but for a more constrained system where more symmetry conditions are imposed and this in agreement with the suggestion of the kinetic theory. The results, when restricted at second order with respect to equilibrium, are the same of the previously cited model but under the further restriction of full symmetries.Comment: arXiv admin note: substantial text overlap with arXiv:1410.405

    Snyder-de Sitter model from two-time physics

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    We show that the symplectic structure of the Snyder model on a de Sitter background can be derived from two-time physics in seven dimensions and propose a Hamiltonian for a free particle consistent with the symmetries of the model.Comment: 9 page

    Big Ideas of Cryptography in Primary School

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    We present a learning path on cryptography for primary school students (Grade 5), which we designed and tested. The project aims to raise initial awareness of the core ideas of modern cryptography, which are fundamental concepts for becoming informed and active citizens in modern digital society. For this reason, we designed a progression of unplugged activities (sometimes integrated with task-specific, block-based programming environments) to expose students to different cryptographic techniques, where each new activity is motivated by an analysis of the criticalities encountered previously. We used unplugged activities to show that Computer Science (CS) does not necessarily imply the use of digital devices and to allow students to focus on its general scientific principles. We describe the designed learning module, discuss the main hinges in the experiment, and reflect on the lessons learned. The final evaluation showed excellent learning outcomes and high satisfaction with the activities. As cryptography uses mathematical tools (e.g., modular arithmetic, statistics), some parts of which are within reach of primary school children but rarely taught to them, it was possible to dwell on these aspects, making them experience mathematical objects in a non-standard context, and also stimulating a greater awareness of the impact of mathematics and CS in everyday life

    An exact fluid model for relativistic electron beams: The many moments case

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    An interesting and satisfactory fluid model has been proposed in literature for the the description of relativistic electron beams. It was obtained with 14 independent variables by imposing the entropy principle and the relativity principle. Here the case is considered with an arbitrary number of independent variables, still satisfying the above mentioned two principles; these lead to conditions whose general solution is here found. We think that the results satisfy also a certain ordering with respect to a smallness parameter ϵ\epsilon measuring the dispersion of the velocity about the mean; this ordering generalizes that appearing in literature for the 14 moments case

    Extended Thermodynamics for Dense Gases up to Whatever Order and with Only Some Symmetries

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    Extended Thermodynamics of dense gases is characterized by two hierarchies of field equations, which allow one to overcome some restrictions on the generality of the previous models. This idea has been introduced by Arima, Taniguchi, Ruggeri and Sugiyama. In~the case of a 14-moment model, they have found the closure of the balance equations up to second order with respect to equilibrium. Here, the closure is obtained up to whatever order and imposing only the necessary symmetry conditions. It comes out that the first non-symmetric parts of the higher order fluxes appear only at third order with respect to equilibrium, even if Arima, Taniguchi, Ruggeri and Sugiyama found a non-symmetric part proportional to an arbitrary constant also at first order with respect to equilibrium. Consequently, this constant must be zero, as Arima, Taniguchi, Ruggeri and Sugiyama assumed in the applications and on an intuitive ground

    The general exact solution for the many moments macroscopic approach to extended thermodynamics of polyatomic gases

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    A new model for Polyatomic and for Dense Gases has been proposed in literature in the last five years in the framework of Extended Thermodynamics. The case with an arbitrary but fixed number of moments has been recently studied, both with the kinetic approach than with the macroscopic approach; this last one is more general and includes the results of the kinetic approach only as a particular case. \\ Scope of the "closure problem" is to find the expression of some arbitrary functions which appear in the balance equations. Up to now only a recurrence procedure has been published which outlines how to find the solution of this problem with the macroscopic approach; by using this procedure, a numberable set of solutions has been found and written explicitly, while we find here the most general exact solution. It is determined except for some arbirary terms and it is interesting that these terms appear also in the 24 moments model; so we find here that they are transmitted from the model with 24 moments to those with an arbitrary number of moments, without any further arbitrary term

    Platinated Nucleotides are Substrates for the Human Mitochondrial Deoxynucleotide Carrier (DNC) and DNA Polymerase g: Relevance for the Development of New Platinum-Based Drugs.

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    cis-[PtCl2(NH3)2] (cisplatin) is among the highest effective antitumor drugs used for the chemotherapeutic treatment of a broad range of malignancies. Recently, alongside with the classical direct bond to DNA, an alternative mechanism of action mediated by N7 platinated nucleotides has been suggested for cisplatin. Considering that mitochondria play an important role in cell death activation and in a significant portion of the clinical activity and pharmacological properties associated with cisplatin, aim of this research was to evaluate the possibility that platinated deoxynucleotides, as the model complex [Pt(dien)(N7-5’-dGTP)] (1), dien=diethylenetriamine, could be transported into mitochondria and then incorporated into mtDNA. The kinetic characterization has revealed that the mitochondrial deoxynucleotide carrier (DNC) transports complex 1 with high affinity. Finally, a highly efficient in organello DNA synthesis system, followed by ICP-AES, has demonstrated that [Pt(dien)(N7-5’-dGTP)] is incorporated in the mitochondrial DNA by DNA polymerase g. These results may have critical implications in the development of new generations of anticancer and/or antiviral nucleotide analogues with more specific cellular targets and fewer side effects

    A Minimal Snap Extension to Improve the Treatment of Integer Data: A Constructionist Approach

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    Block based programming environments are a fundamental resource in introducing students to coding, an activity that has been proven to be useful in the development of competences laying in the field of mathematics. Unfortunately, it has been recently shown that Scratch, the most famous and diffused among those languages, presents an important lack in the treatment of Integer data: it does not provide easy and intuitive instruments to face problems dealing with the division with remainder. This conflicts with Scratch’s aim and could also bring students to create misconceptions about the division operation. For this reason, a minimal Snap extension will be here proposed, which overcomes this problem by creating a block environment more pertinent from a mathematical perspective
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