Search results for "general [Pulsars]"
showing 10 items of 19888 documents
Quasi-periodical kinetic instabilities in minimum-B confined plasma
2022
We present the results of an experimental investigation of quasi-periodical kinetic instabilities exhibited by magnetically confined electron cyclotron resonance heated plasmas. The instabilities were detected by measuring plasma microwave emission, electron losses, and wall bremsstrahlung. The instabilities were found to be grouped into fast sequences of periodic plasma losses, separated by ∼100 µs between the bursts, followed by 1–10 ms quiescent periods before the next event. Increasing the plasma energy content by adjusting the plasma heating parameters, in particular the magnetic field strength, makes the instabilities more chaotic in the time domain. Statistical analysis reveals that …
A novel approach to β-decay: PANDORA, a new experimental setup for future in-plasma measurements
2022
International audience; Theoretical predictions as well as experiments performed at storage rings have shown that the lifetimes of β-radionuclides can change significantly as a function of the ionization state. In this paper we describe an innovative approach, based on the use of a compact plasma trap to emulate selected stellar-like conditions. It has been proposed within the PANDORA project (Plasmas for Astrophysics, Nuclear Decay Observation and Radiation for Archaeometry) with the aim to measure, for the first time in plasma, nuclear β-decay rates of radionuclides involved in nuclear-astrophysics processes. To achieve this task, a compact magnetic plasma trap has been designed…
Plasma-wall interaction studies within the EUROfusion consortium: Progress on plasma-facing components development and qualification
2017
This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014-2018 under grant agreement No 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission.
Kohn-Sham Decomposition in Real-Time Time-Dependent Density-Functional Theory An Efficient Tool for Analyzing Plasmonic Excitations
2017
The real-time-propagation formulation of time-dependent density-functional theory (RT-TDDFT) is an efficient method for modeling the optical response of molecules and nanoparticles. Compared to the widely adopted linear-response TDDFT approaches based on, e.g., the Casida equations, RT-TDDFT appears, however, lacking efficient analysis methods. This applies in particular to a decomposition of the response in the basis of the underlying single-electron states. In this work, we overcome this limitation by developing an analysis method for obtaining the Kohn-Sham electron-hole decomposition in RT-TDDFT. We demonstrate the equivalence between the developed method and the Casida approach by a be…
High-resolution laser spectroscopy of long-lived plutonium isotopes
2017
Long-lived isotopes of plutonium were studied using two complementary techniques, high-resolution resonance ionisation spectroscopy (HR-RIS) and collinear laser spectroscopy (CLS). Isotope shifts have been measured on the $5f^67s^2\ ^7F_0 \rightarrow 5f^56d^27s\ (J=1)$ and $5f^67s^2\ ^7F_1 \rightarrow 5f^67s7p\ (J=2)$ atomic transitions using the HR-RIS method and the hyperfine factors have been extracted for the odd mass nuclei $^{239,241}$Pu. Collinear laser spectroscopy was performed on the $5f^67s\ ^8F_{1/2} \rightarrow J=1/2\; (27523.61\text{cm}^{-1})$ ionic transition with the hyperfine $A$ factors measured for $^{239}$Pu. Changes in mean-squared charge radii have been extracted and s…
À bas la sélection ! Misère de la critique
2019
International audience; La critique de la sélection à l'entrée de l'université repose sur une vision misérabiliste des étudiants de milieu populaire et ne remet pas en question les inégalités au sein du système d'éducation. Il existe sans doute mille bonnes raisons d'être hostile à Parcoursup et à la réforme du baccalauréat, comme il existe de solides raisons de protester contre les conditions de travail des professeurs, des enseignants-chercheurs et des étudiants… Le propos de ce texte n'est pas de participer aux débats sur le bien-fondé des réformes ; il n'est ni de les défendre ni de les contester, mais d'interroger les cadres de la critique de la sélection que ces réformes sont censées …
The effect of inbreeding rate on fitness, inbreeding depression and heterosis over a range of inbreeding coefficients
2014
Understanding the effects of inbreeding and genetic drift within populations and hybridization between genetically differentiated populations is important for many basic and applied questions in ecology and evolutionary biology. The magnitudes and even the directions of these effects can be influenced by various factors, especially by the current and historical population size (i.e. inbreeding rate). Using Drosophila littoralis as a model species, we studied the effect of inbreeding rate over a range of inbreeding levels on (i) mean fitness of a population (relative to that of an outbred control population), (ii) within‐population inbreeding depression (reduction in fitness of offspring fro…
External Developmental Assets and Positive Identity Among Emerging Adults in Norway, Romania, Slovenia, and Turkey
2021
The present study adopts The Developmental Assets and Positive Youth Development (PYD) perspectives which (in contrast to the deficit-based approaches which highlight risks and deficit in youth development) claim that young people have potencies to achieve optimal development if supported by their social environment. Extant research indicates that developmental assets are linked with a variety of thriving indicators. The present research aimed to contribute to the PYD research by examining the external developmental assets (support, empowerment, and boundaries and expectations) emerging adults (N= 2055; age range = 18–28) perceived in their social environment and the level of their positive…
Editorial: Positive Technology: Designing E-experiences for Positive Change
2019
While there is little doubt that our lives are becoming increasingly digital, whether this change is for the better or for the worse is far from being settled. Rather, over the past years concerns about the personal and social impacts of technologies have been growing, fueled by dystopian Orwellian scenarios that almost on daily basis are generously dispensed by major Western media outlets. According to a recent poll involving some 1,150 experts, 47% of respondents predict that individuals’ well-being will bemore helped than harmed by digital life in the next decade, while 32% say people’s well-being will bemore harmed than helped. Only 21% of those surveyed indicated that the impact of tec…
Positron Surface States on Clean and Oxidized Al and in Surface Vacancies
1983
This Letter reports on the first discrete-lattice calculation of positron surface states on the surfaces of Al. The authors reproduce the observed values and anisotropy of the binding energies on clean surfaces, and predict the surface-state lifetimes. The temperature-independent lateral diffusion constant is calculated. Monovacancies on surfaces are predicted not to trap positrons. The effect of ordered chemisorbed monolayers of oxygen is investigated: Oxidation makes the surface state unstable with respect to positronium emission. Peer reviewed