The 12CO/13CO ratio in AGB stars of different chemical type-Connection to the 12C/13C ratio and the evolution along the AGB

The aim of this paper is to investigate the evolution of the 12C/13C ratio along the AGB through the circumstellar 12CO/13CO ratio. This is the first time a sample including a significant number of M- and S-type stars is analysed together with a carbon-star sample of equal size, making it possible to investigate trends among the different types and establish evolutionary effects. The circumstellar 12CO/13CO abundance ratios are estimated through a detailed radiative transfer analysis of single-dish radio line emission observations. First, the 12CO radiative transfer is solved, assuming an abundance (dependent on the chemical type of the star), to give the physical parameters of the gas, i.e. mass-loss rate, gas expansion velocity, and gas temperature distribution. Then, the 13CO radiative transfer is solved using the results of the 12CO model giving the 13CO abundance. Finally, the 12CO/13CO abundance ratio is calculated. The circumstellar 12CO/13CO abundance ratio differs between the three spectral types. This is consistent with what is expected from stellar evolutionary models assuming that the spectral types constitute an evolutionary sequence; however, this is the first time this has been shown observationally for a relatively large sample covering all three spectral types. The median value of the 13CO abundance in the inner circumstellar envelope is 1.6x10^-5, 2.3x10^-5, and 3.0x10^-5 for the M-type, S-type, and carbon stars of the sample, respectively, corresponding to 12CO/13CO abundance ratios of 13, 26, and 34, respectively. Interestingly, the abundance ratio spread of the carbon stars is much larger than for the M- and S-type stars, even when excluding J-type carbon stars, in line with what could be expected from evolution on the AGB. We find no correlation between the isotopologue ratio and the mass-loss rate, as would be expected if both increase as the star evolves.Comment: 11 pages, 5 figures, accepted for publication in A&

The physics and chemistry of circumstellar envelopes of S-stars on the AGB

The S-stars have been suggested to be a brief transitional phase as stars evolve from oxygen-rich M-type stars into carbon stars, through the dredge up of carbon from He-shell burning. As possible transition objects, S-stars might help achieve a deeper understanding of the chemical evolution as a star ascends the AGB, as well as shed more light on the mass-loss mechanism. We have initiated a large survey of 40 S-stars to observe line emission in common molecules such as CO, SiO, HCN, CS and SiS. Detailed radiative transfer modelling of multi-transition CO radio line observations towards a sample of 40 S-stars shows that the mass-loss rate distribution of S-stars is consistent with those found for M-type AGB stars and carbon stars. Initial results from modelling of the circumstellar SiO emission are also presented.Comment: 2 pages, 1 figure, to appear in Proceedings from 'Why Galaxies Care About AGB stars

The mass-loss rates and molecular abundances of S-type AGB stars

The S-type stars are believed to have a C/O-ratio close to unity (within a few percent). They are considered to represent an intermediate evolutionary stage as AGB stars evolve from oxygen-rich M-type stars into carbon stars. As possible transition objects the S-type stars could give important clues to the mass-loss mechanism(s) and to the chemical evolution along the AGB. Using observations of circumstellar radio line emission in combination with a detailed radiative transfer analysis, we have estimated mass-loss rates and abundances of chemically important molecules (SiO, HCN) for a sample of 40 S-type AGB stars. The results will be compared to previous results for M-type and carbon stars.Comment: To appear in the proceedings of Why Galaxies Care About AGB stars I

Esotericism throughout the centuries

Review of Wouter J. Hanegraaff's Esotericism and the Academy: Rejected Knowledge in Western Culture (Cambridge University, 2012)

Investigating the prerequisites of a service guarantee for soil damages

Timber harvesting is a disturbance which can alter the natural order of the ecosystem, causing potentially harmful consequences, especially on water quality. These damages are commonly present where forestry machines have ruptured or compacted the organic layer of the forest floor. Therefore, protection of forest soil during forestry operations has become an increasing concern, and many forestry companies are actively working towards implementing soil protection strategies. SCA Skog AB proposed the possibility of implementing a service guarantee as a strategy to meet this goal. Therefore, this project was undertaken to investigate the prerequisites of creating a service guarantee for soil damages. In this study, the aim was to assess the possibilities to create a predictive model and to use the model result as an input to calculate the cost of implementing the service guarantee. A binomial logistic regression analysis method was used, and purposeful selection was chosen as the method of selecting variables for the predictive model. Data were provided by SCA Skog AB. The result of this investigation shows that the current dataset is not suitable for creating predictive models. Although it was possible to detect correlation between the independent variables, and rutting and severe rutting, it was not strong enough to be used in a prediction model. As it was not possible to predict the risk of rutting and revere Rutting, an average was calculated to provide the expected number of soil damages detected each year. Thus, the second aim, to calculate cost estimate intervals for a guarantee was possible to fulfill. Depending on the chosen Soil Damage Recovery Scenario, Assessment Sample Size, Employee option and Forest Owner Compensation, it was concluded that the implementation cost of the service guarantee should range between 347 028 and 2 012 254 SEK/year in total costs for the studied area, which would be equivalent to 0.41 - 2.25 SEK/m3sub (cubic meters, solid volume under bark)

Politics of Taxonomy in Postcolonial Indonesia: Ethnic Traditions between Religionisation and Secularisation

The article discusses the politics of taxonomy that drive the entangled dynamics of religionisation and secularisation of ethnic traditions in postcolonial Indonesia, and the associated sociopolitical context. Defined in accordance with both emic notions of agamasasi (religionisation) and the concept of religion-making originally advanced by Arvind-Pal S. Mandair and Markus Dressler in 2011, “religionisation” relates to three interrelated processes that have had distinct ramifications in the different periods of postcolonial Indonesian history: (1) the way in which the Indonesian state has reified and institutionalised ‘religion’ as a monotheistic, revealed, and scriptural world religion; (2) the state-sanctioned positioning of ‘religion’ as distinct from local forms of spiritual belief, resulting in the desacralisation and secularisation of the latter; and (3) the way in which adherents of ethnic spiritualities have reframed and transformed their respective traditions in order to reflect the state-defined notion of ‘religion,’ and, in doing so, also accepted and strengthened the state discourse of development and modernity. The article also supports Nils Bubandt’s observation that the boundaries between the secular and the spiritual have always remained porous in Indonesian society as even so-called secular Indonesian politicians have tended to fall back on locally flavoured mystical or magical beliefs and practices in order to secure their political power

Real-Time Reinforcement Learning

Les processus de décision markovien (MDP), le cadre mathématiques sous-jacent à la plupart des algorithmes de l'apprentissage par renforcement (RL) est souvent utilisé d'une manière qui suppose, à tort, que l'état de l'environnement d'un agent ne change pas pendant la sélection des actions. Puisque les systèmes RL basés sur les MDP classiques commencent à être appliqués dans les situations critiques pour la sécurité du monde réel, ce décalage entre les hypothèses sous-jacentes aux MDP classiques et la réalité du calcul en temps réel peut entraîner des résultats indésirables. Dans cette thèse, nous introduirons un nouveau cadre dans lequel les états et les actions évoluent simultanément, nous montrerons comment il est lié à la formulation MDP classique. Nous analyserons des algorithmes existants selon la nouvelle formulation en temps réel et montrerons pourquoi ils sont inférieurs, lorsqu'ils sont utilisés en temps réel. Par la suite, nous utiliserons ces perspectives pour créer un nouveau algorithme Real-Time Actor Critic qui est supérieur au Soft Actor Critic contrôle continu de l'état de l'art actuel, aussi bien en temps réel qu'en temps non réel.Markov Decision Processes (MDPs), the mathematical framework underlying most algorithms in Reinforcement Learning (RL), are often used in a way that wrongfully assumes that the state of an agent's environment does not change during action selection. As RL systems based on MDPs begin to find application in real-world safety critical situations, this mismatch between the assumptions underlying classical MDPs and the reality of real-time computation may lead to undesirable outcomes. In this thesis, we introduce a new framework, in which states and actions evolve simultaneously, we show how it is related to the classical MDP formulation. We analyze existing algorithms under the new real-time formulation and show why they are suboptimal when used in real-time. We then use those insights to create a new algorithm, Real-Time Actor Critic (RTAC) that outperforms the existing state-of-the-art continuous control algorithm Soft Actor Critic both in real-time and non-real-time settings

Making sense of personal and global problems: an analysis of the writings and lectures of Rauni-Leena Luukanen-Kilde

Rauni-Leena Luukanen-Kilde (b. 1939) is a well-known figure in the Finnish alternative spiritual milieu. She is an author and lecturer on parapsychology and ufology and has been a guest on several talk shows in the Nordic countries. The topics discussed by Luukanen-Kilde range from the psychic abilities of mankind to visitations from extraterrestrial beings. Since the mid-1980s Luukanen-Kilde has developed conspiracy theories about an elite group governing the world in secret. Luukanen-Kilde is a bestselling author and draws audiences of several hundreds to her talks. Her conspiracy theory view of the world offers explanations for all kinds of personal, national, as well as global problems and disasters. Personal health problems, tragic incidents such as school shootings, economic crises and unemployment, earthquakes and floods can, according to her belief system, all be attributed to a single cause; namely to the actions of a clandestine, malevolent group. The popularity of Luukanen-Kilde’s books and lectures can be seen as an example of how people in late modernity are seeking alternative interpretations of themselves and of world events.