Identifying magnetic reconnection in 2D Hybrid Vlasov Maxwell simulations with Convolutional Neural Networks

Magnetic reconnection is a fundamental process that quickly releases magnetic energy stored in a plasma.Identifying, from simulation outputs, where reconnection is taking place is non-trivial and, in general, has to be performed by human experts. Hence, it would be valuable if such an identification process could be automated. Here, we demonstrate that a machine learning algorithm can help to identify reconnection in 2D simulations of collisionless plasma turbulence. Using a Hybrid Vlasov Maxwell (HVM) model, a data set containing over 2000 potential reconnection events was generated and subsequently labeled by human experts. We test and compare two machine learning approaches with different configurations on this data set. The best results are obtained with a convolutional neural network (CNN) combined with an 'image cropping' step that zooms in on potential reconnection sites. With this method, more than 70% of reconnection events can be identified correctly. The importance of different physical variables is evaluated by studying how they affect the accuracy of predictions. Finally, we also discuss various possible causes for wrong predictions from the proposed model.Comment: 16 pages, 9 figures and 5 tabel

Dielectric study of the glass transition: correlation with calorimetric data

The glass transition in amorphous poly(ethylene terephthalate) is studied by thermally stimulated depolarization currents (TSDC) and differential scanning calorimetry (DSC). The ability of TSDC to decompose a distributed relaxation, as the glass transition, into its elementary components is demonstrated. Two polarization techniques, windows polarization (WP) and non-isothermal windows polarization (NIW), are employed to assess the influence of thermal history in the results. The Tool-Narayanaswami-Moynihan (TNM) model has been used to fit the TSDC spectra. The most important contributions to the relaxation comes from modes with non-linearity (x) around 0.7. Activation energies yield by this model are located around 1eV for polarization temperature (Tp) below 50C and they raise up to values higher than 8eV as Tp increases (up to 80C). There are few differences between results obtained with WP and NIW but, nonetheless, these are discussed. The obtained kinetic parameters are tested against DSC results in several conditions. Calculated DSC curves at several cooling and heating rates can reproduce qualitatively experimental DSC results. These results also demonstrate that modelization of the non-equilibrium kinetics involved in TSDC spectroscopy is a useful experimental tool for glass transition studies in polar polymers.Comment: 13 pages, 2 tables, 10 figures; minor change

Mycotic aneurysm of the right iliac artery: imaging diagnosis and correlation with pathological findings

We report the case of a 55-year-old woman who presented at the emergency department with hypogastric pain, fever, clinical signs of sepsis and a critical inflammation syndrome in her blood test values. CT-scan of the abdomen demonstrated an infected aneurysm of the right iliac artery. The patient underwent surgery with a favorable outcome. Histological examination of resected artery was performed and compared to the CT features. The authors review the literature and stress the importance of early diagnosis and treatement

Transitions/relaxations in polyester adhesive/PET system

The correlations between the transitions and the dielectric relaxation processes of the oriented poly(ethylene terephthalate) (PET) pre-impregnated of the polyester thermoplastic adhesive have been investigated by differential scanning calorimetry (DSC) and dynamic dielectric spectroscopy (DDS). The thermoplastic polyester adhesive and the oriented PET films have been studied as reference samples. This study evidences that the adhesive chain segments is responsible for the physical structure evolution in the PET-oriented film. The transitions and dielectric relaxation modes’ evolutions in the glass transition region appear characteristic of the interphase between adhesive and PET film, which is discussed in terms of molecular mobility. The storage at room temperature of the adhesive tape involves the heterogeneity of the physical structure, characterized by glass transition dissociation. Thus, the correlation between the transitions and the dielectric relaxation processes evidences a segregation of the amorphous phases. Therefore, the physical structure and the properties of the material have been linked to the chemical characteristics

Demasculinization of male guppies increases resistance to a common and harmful ectoparasite

Parasites are detrimental to host fitness and therefore should strongly select for host defence mechanisms. Yet, hosts vary considerably in their observed parasite loads. One notable source of inter-individual variation in parasitism is host sex. Such variation could be caused by the immunomodulatory effects of gonadal steroids. Here we assess the influence of gonadal steroids on the ability of guppies (Poecilia reticulata) to defend themselves against a common and deleterious parasite (Gyrodactylus turnbulli). Adult male guppies underwent 31 days of artificial demasculinization with the androgen receptor-antagonist flutamide, or feminization with a combination of flutamide and the synthetic oestrogen 17 β-estradiol, and their parasite loads were compared over time to untreated males and females. Both demasculinized and feminized male guppies had lower G. turnbulli loads than the untreated males and females, but this effect appeared to be mainly the result of demasculinization, with feminization having no additional measurable effect. Furthermore, demasculinized males, feminized males and untreated females all suffered lower Gyrodactylus-induced mortality than untreated males. Together, these results suggest that androgens reduce the ability of guppies to control parasite loads, and modulate resistance to and survival from infection. We discuss the relevance of these findings for understanding constraints on the evolution of resistance in guppies and other vertebrates

Using Evidence in a Highly Fragmented Legislature: The Case of Colombia's Health System Reform

This chapter examines how evidence is used in major policy health policy initiatives in a highly contested political context. Through a case study of legislation proposed in the context of Colombia’s ongoing health systems reformed process, it explores how such use is affected by the specific role played by the legislature within a highly fragmented polity. It draws on an analysis of evidence cited in the drafting of relevant laws in the process of health systems reform. Reflecting the role of the legislature in Colombia’s contested political system, evidence cited in legislative debates was unable to forge consensus amongst relevant policy actors over health system reforms. While scientific research was available and at the disposal of legislators, it was unable to provide the common ground on which to overcome embedded policy positions and form the basis of compromise over the direction of health systems reforms

Evidence Use and the Institutions of the State: The Role of Parliament and the Judiciary

This chapter explores the role of parliaments and the judiciary in shaping evidence use in health policy making. Most analyses of the role of scientific evidence focus on the executive, i.e. national governments and ministries of health, as the key state actors in health policy and health system governance. This chapter shifts attention to the other two powers within the state, the legislative and the judiciary. Using the examples analysed in this book the chapter examines how parliaments can use evidence to inform legislative processes and to hold governments to account, although there are substantial differences between countries and political systems. However, there was little suggestion that such approaches were undertaken systematically. In cases in which policies are brought to court, judges may have to deal with scientific evidence within a country’s legal and constitutional framework, again with significant differences between national legal practices