Smoothed Particle Hydrodynamics simulations of the core-degenerate scenario for Type Ia supernovae

The core-degenerate (CD) scenario for type Ia supernovae (SN Ia) involves the merger of the hot core of an asymptotic giant branch (AGB) star and a white dwarf, and might contribute a non-negligible fraction of all thermonuclear supernovae. Despite its potential interest, very few studies, and based on only crude simplifications, have been devoted to investigate this possible scenario, compared with the large efforts invested to study some other scenarios. Here we perform the first three-dimensional simulations of the merger phase, and find that this process can lead to the formation of a massive white dwarf, as required by this scenario. We consider two situations, according to the mass of the circumbinary disk formed around the system during the final stages of the common envelope phase. If the disk is massive enough, the stars merge on a highly eccentric orbit. Otherwise, the merger occurs after the circumbinary disk has been ejected and gravitational wave radiation has brought the stars close to the Roche lobe radius on a nearly circular orbit. Not surprisingly, the overall characteristics of the merger remnants are similar to those found for the double-degenerate (DD) scenario, independently of the very different core temperature and of the orbits of the merging stars. They consist of a central massive white dwarf, surrounded by a hot, rapidly rotating corona and a thick debris region.Comment: 17 pages, 10 figures. Accepted for publication in MNRA

A white dwarf merger as progenitor of the anomalous X-ray pulsar 4U 0142+61?

It has been recently proposed that massive fast-rotating highly-magnetized white dwarfs could describe the observational properties of some of Soft Gamma-Ray Repeaters (SGRs) and Anomalous X-Ray Pulsars (AXPs). Moreover, it has also been shown that high-field magnetic (HFMWDs) can be the outcome of white dwarf binary mergers. The products of these mergers consist of a hot central white dwarf surrounded by a rapidly rotating disk. Here we show that the merger of a double degenerate system can explain the characteristics of the peculiar AXP 4U 0142+61. This scenario accounts for the observed infrared excess. We also show that the observed properties of 4U 0142+6 are consistent with an approximately 1.2 M_{\sun} white dwarf, remnant of the coalescence of an original system made of two white dwarfs of masses 0.6\, M_{\sun} and 1.0\, M_{\sun}. Finally, we infer a post-merging age $\tau_{\rm WD}\approx 64$ kyr, and a magnetic field $B\approx 2\times 10^8$ G. Evidence for such a magnetic field may come from the possible detection of the electron cyclotron absorption feature observed between the $B$ and $V$ bands at $\approx 10^{15}$ Hz in the spectrum of 4U 0142+61.Comment: to appear in ApJ Letter

Decellularization of tumours: A new frontier in tissue engineering

Cancer is one of the leading causes of death worldwide. The tumour extracellular matrix (ECM) has unique features in terms of composition and mechanical properties, resulting in a structurally and chemically different ECM to that of native, healthy tissues. This paper reviews to date the efforts into decellularization of tumours, which in the authors’ view represents a new frontier in the ever evolving field of tumour tissue engineering. An overview of the ECM and its importance in cancer is given, ending with examples of research using decellularized tumours, which has already indicated potential therapeutic targets, unravelled malignancy mechanisms or response to chemotherapy agents. The review highlights that more research is needed in this area, which can answer important questions related to tumour formation and progression to ultimately identify new and effective therapeutic targets. Within the near-future of personalized medicine, this research can create patient-specific tumour models and therapeutic regimes

White dwarf dynamical interactions and fast optical transients

This is the author accepted manuscript. The final version is available from OUP via the DOI in this record.Recent advances in time-domain astronomy have uncovered a new class of optical transients with timescales shorter than typical supernovae and a wide range of peak luminosities. Several subtypes have been identi ed within this broad class, including Ca-rich transients, .Ia supernovae, and fast/bright transients. We examine the predic- tions from a state-of-the-art grid of three-dimensional simulations of dynamical white dwarf interactions in the context of these fast optical transients. We nd that for colli- sions involving carbon-oxygen or oxygen-neon white dwarfs the peak luminosities and durations of the light curves in our models are in good agreement with the properties of fast/bright transients. When one of the colliding white dwarfs is made of helium the properties of the light curves are similar to those of Ca-rich gap transients. The model lightcurves from our white dwarf collisions are too slow to reproduce those of .Ia SNe, and too fast to match any normal or peculiar Type Ia supernova.This work was partially funded by the MINECO grant AYA2014-59084-P and by the AGAUR (EG-B). CB acknowledges support from grants NASA ADAP NNX15AM03G S01 and NSF/AST-1412980. We acknowl- edge the useful comments of our referee, which helped in improving the original version of the paper

Perancangan Buku Bergambar Dengan Daya Tarik Pop-up Tentang Manajemen Emosi Untuk Anak-anak Usia 4-6 Tahun

Buku bergambar ini memperkenalkan sekaligus mengajarkan kepada anak-anak usia 4 – 6tahun mengenai emosi yang mereka miliki terutama emosi marah. Buku ini memperkenalkan anakanaktersebut melalui cerita fantasi dan daya tarik pop-up yang disuguhkan menarik bagi mereka.Selain memperkenalkan buku ini juga mengajarkan cara-cara mengendalikan amarah yang dapatdilakukan dengan sederhana oleh anak-anak. Sehingga anak-anak dapat belajar sejak dini untukmengenali dan mengendalikan kemarahan mereka agar tidak berlebihan atau dilampiaskan secaranegati

Students have their say: factors involved in students' perception on their engineering degree

This is an Accepted Manuscript of an article published by Taylor & Francis in European Journal of Engineering Education on 02-11-2021, available online: http://www.tandfonline.com/10.1080/03043797.2021.1977244[EN] Higher Education institutions strive to continuously improve to meet students' expectations. Thus, it is vital to understand the factors involved in students' perceptions on their degree and on the quality of the teaching received. Engineering degrees require specific conditions due to their complex practical lessons and the need for high applicability, and our aim is to identify what affects the quality of the teaching delivered to our engineering students. Previous research on Higher Education focused on students' perception has been based on closed response questionnaires, which do not provide enough information. Hence, we asked students to freely make remarks, positive and/or negative on an open response questionnaire, and the qualitative analysis of their answers led to the description of a four-category figure (Teacher, Subject, Student, and Degree) revealing students' perceptions. Open response questionnaires offer administrators valuable information, as a complement to the quantitative analysis based on closed response questionnaires.Aznar-Mas, LE.; Atarés Huerta, LM.; Marin-Garcia, JA. (2021). Students have their say: factors involved in students' perception on their engineering degree. European Journal of Engineering Education. 46(6):1007-1025. https://doi.org/10.1080/03043797.2021.19772441007102546