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

Perancangan Komik Digital Menggunakan Aplikasi Line Webtoon Tentang Pola Makan Sesuai Golongan Darah Untuk Remaja

Komik digital ini dibuat untuk memberikan informasi kepada remaja SMP dan SMA tentang pentingnya menjaga kesehatan dengan mengatur pola makan sesuai golongan darah

Helminth communities of herons (Aves: Ardeidae) in southern Italy

The helminth communities of nine species of herons from southern Italy were studied and compared. Of 24 taxa found including seven digeneans, seven nematodes, six cestodes and four acanthocephalans, only five taxa were found in more than one heron species, and five of the 21 taxa that could be identified to species level were classified as 'heron specialists'. The total number of helminth species per heron species ranged from 1 in Botaurus stellaris to 9 in Ixobrychus minutus with infection levels generally low. A statistical comparison was carried out for herons with a sample size >. 5. At the infracommunity level, only I. minutus clearly differed from other heron species. Diversity parameters of heminth infracommunities did not significantly differ among heron species. Species richness ranged from just 0.3 to 2.3 helminth taxa per individual host, and the Brillouin index, from 0 to 0.3. Total helminth abundance did not exceed 40 worms per host except in a single case of Ardeola ralloides. Infracommunities clearly were dominated by single helminth species. The present study confirms a depauperate helminth community in herons from southern Italy. Comparison with data from Spain and the Czech Republic showed strong quantitative similarities with values obtained in the present study. Results also suggest that the composition of local helminth communities are strongly variable depending on geographical location as is demonstrated by comparison with data from other European areas. However, whether herons in Europe naturally host depauperate helminth communities or these communities are depauperate because of other factors is unknow

A Novel Device for the Measurement of the Mechanical and Magnetic Axes of Superconducting Magnet Assemblies for Accelerators

In the context of the LHC superconducting magnet production, especially for dipoles and quadrupoles due to their complexity, it is foreseen to perform acceptance tests, at an early production stage, to detect possible significant deviations from the design values. The knowledge of the magnetic field geometry is very important, especially for the main magnets. In order to get this information a new device has been conceived that measures the magnets at room temperature during different stages of construction. This device incorporates a sensitive measuring probe and an efficient data acquisition system because the coils are only powered at about 10-5 of the nominal D.C. current. It is dedicated to Quadrupole and Dipole (by using Quadrupole-Configured Dipole (QCD) transformation) magnets, but is also easily adaptable to higher order magnets (n = 3, 4 and 5) by specific orientation of the search coils. It is equipped with magnetic sensors (4 fixed tangential coils and AC excitation current for the magnet) and position sensors (3D-laser tracker and light reflector) that allow the simultaneous detection of the magnetic field axis and the cold bore axis. It is equipped as well with a set of 4 LEDs and associated with a CCD camera that allows both the measurement of the cold bore diameter and its position with respect to the mole. This paper describes the system and reports the first results measured on the pre-series magnets recently assembled

Mediterranean Sea response to climate change in an ensemble of twenty first century scenarios

The Mediterranean climate is expected to become warmer and drier during the twenty-first century. Mediterranean Sea response to climate change could be modulated by the choice of the socio-economic scenario as well as the choice of the boundary conditions mainly the Atlantic hydrography, the river runoff and the atmospheric fluxes. To assess and quantify the sensitivity of the Mediterranean Sea to the twenty-first century climate change, a set of numerical experiments was carried out with the regional ocean model NEMOMED8 set up for the Mediterranean Sea. The model is forced by air–sea fluxes derived from the regional climate model ARPEGE-Climate at a 50-km horizontal resolution. Historical simulations representing the climate of the period 1961–2000 were run to obtain a reference state. From this baseline, various sensitivity experiments were performed for the period 2001–2099, following different socio-economic scenarios based on the Special Report on Emissions Scenarios. For the A2 scenario, the main three boundary forcings (river runoff, near-Atlantic water hydrography and air–sea fluxes) were changed one by one to better identify the role of each forcing in the way the ocean responds to climate change. In two additional simulations (A1B, B1), the scenario is changed, allowing to quantify the socio-economic uncertainty. Our 6-member scenario simulations display a warming and saltening of the Mediterranean. For the 2070–2099 period compared to 1961–1990, the sea surface temperature anomalies range from +1.73 to +2.97 °C and the SSS anomalies spread from +0.48 to +0.89. In most of the cases, we found that the future Mediterranean thermohaline circulation (MTHC) tends to reach a situation similar to the eastern Mediterranean Transient. However, this response is varying depending on the chosen boundary conditions and socio-economic scenarios. Our numerical experiments suggest that the choice of the near-Atlantic surface water evolution, which is very uncertain in General Circulation Models, has the largest impact on the evolution of the Mediterranean water masses, followed by the choice of the socio-economic scenario. The choice of river runoff and atmospheric forcing both have a smaller impact. The state of the MTHC during the historical period is found to have a large influence on the transfer of surface anomalies toward depth. Besides, subsurface currents are substantially modified in the Ionian Sea and the Balearic region. Finally, the response of thermosteric sea level ranges from +34 to +49 cm (2070–2099 vs. 1961–1990), mainly depending on the Atlantic forcing

Revisión bibliográfica de implantología bucofacial del año 2009. 1ª parte

Debido al amplio número de publicaciones que existen sobre Implantología Bucofacial, resultadifícil para el odontólogo seleccionar y leer de forma crítica una cantidad suficiente de artículos que puedan aportarle una información útil para su praxis diaria. En este artículo se pretende sintetizar la información más relevante que se encuentra en las revistas indexadas de la especialidad publicadas durante el año 2009

Revisión bibliográfica de implantología bucofacial del año 2009. 2ª parte

Debido al amplio número de publicaciones que existen sobre Implantología Bucofacial, resulta difícil para el odontólogo seleccionar y leer de forma crítica una cantidad suficiente de artículos que puedan aportarle una información útil para su praxis diaria. En este artículo pretendemos sintetizar la información más relevante que se encuentra en las revistas indexadas de la especialidad publicadas el año 2009

Non-thermal emission processes in massive binaries

In this paper, I present a general discussion of several astrophysical processes likely to play a role in the production of non-thermal emission in massive stars, with emphasis on massive binaries. Even though the discussion will start in the radio domain where the non-thermal emission was first detected, the census of physical processes involved in the non-thermal emission from massive stars shows that many spectral domains are concerned, from the radio to the very high energies. First, the theoretical aspects of the non-thermal emission from early-type stars will be addressed. The main topics that will be discussed are respectively the physics of individual stellar winds and their interaction in binary systems, the acceleration of relativistic electrons, the magnetic field of massive stars, and finally the non-thermal emission processes relevant to the case of massive stars. Second, this general qualitative discussion will be followed by a more quantitative one, devoted to the most probable scenario where non-thermal radio emitters are massive binaries. I will show how several stellar, wind and orbital parameters can be combined in order to make some semi-quantitative predictions on the high-energy counterpart to the non-thermal emission detected in the radio domain. These theoretical considerations will be followed by a census of results obtained so far, and related to this topic... (see paper for full abstract)Comment: 47 pages, 5 postscript figures, accepted for publication in Astronomy and Astrophysics Review. Astronomy and Astrophysics Review, in pres