A walk through the different spectral states of low-mass X-ray binaries

Lage-massa röntgendubbelstersystemen zijn systemen waarin een compact object, een neutronenster of een zwart gat, materie accreteert van een gewone ster die slechts een massa heeft kleiner dan of vergelijkbaar met die van onze zon. De materie-overdracht vindt plaats via een zogeheten accretieschijf waarin het materiaal naar het compacte object spiraliseert, en soms tot slechts een paar kilometer het compacte object nadert. Door interne wrijving wordt de accretieschijf zo heet dat het voornamelijk röntgenstraling uitzendt. Rondom de accretieschijf en het compacte object bevindt zich een heet plasma, de zogenoemde corona, dat röntgen- en gammastraling uitzendt. De geometrie en oorsprong van de corona zijn niet volledig bekend, maar waarnemingen en theoriën bevestigen de aanwezigheid ervan. Gebruik makend van röntgensatellieten bestuderen we de straling afkomstig van deze accretieschijf en corona welk bijdraagt aan het onderzoek aan compacte objecten en hun nabije omgeving. In dit proefschrift bestudeer ik specifieke eigenschappen van de accretieprocessen in röntgendubbelstersystemen. Deze processen manifesteren zich op verschillende manieren en zijn veranderlijk met tijd, leidend tot de verschillende zogeheten spectrale fases. De geometrie en de temperatuur van de accretieschijf en corona zijn karakteristiek in elk van deze fases. Dit proefschrift loopt door de verschillende spectrale fases heen waarbij vanuit een observationeel standpunt verscheidene bijzonderheden van elk van deze fases worden uitgelicht. Dit levert een belangrijke bijdrage aan de algemene kennis op het gebied van accretieprocessen in lage-massa röntgendubbelstersystemen

Iron-line and continuum variations in the XMM-Newton and Suzaku spectra of the neutron-star low-mass X-ray binary 4U 1636-53

We used six simultaneous XMM-Newton and Rossi X-ray Timing Explorer plus five Suzaku observations to study the continuum spectrum and the iron emission line in the neutron-star low-mass X-ray binary 4U 1636-53. We modelled the spectra with two thermal components (representing the accretion disc and boundary layer), a Comptonised component (representing a hot corona), and either a Gaussian or a relativistic line component to model an iron emission line at about 6.5 keV. For the relativistic line component we used either the diskline, laor or kyrline model, the latter for three different values of the spin parameter. The fitting results for the continuum are consistent with the standard truncated disc scenario. We also find that the flux and equivalent width of the iron line first increase and then decrease as the flux of the Comptonised component increases. This could be explained either by changes in the ionisation state of the accretion disc where the line is produced by reflection, or by light bending of the emission from the Comptonised component if the height at which this component is produced changes with mass accretion rate.Comment: Accepted for publication in MNRAS, 16 pages, 10 figures, 5 table

Broad iron emission line and kilohertz quasi-periodic oscillations in the neutron star system 4U 1636-53

Both the broad iron (Fe) line and the frequency of the kilohertz quasi-periodic oscillations (kHz QPOs) in neutron star low-mass X-ray binaries (LMXBs) can potentially provide independent measures of the inner radius of the accretion disc. We use XMM-Newton and simultaneous Rossi X-ray Timing Explorer observations of the LMXB 4U 1636-53 to test this hypothesis. We study the properties of the Fe-K emission line as a function of the spectral state of the source and the frequency of the kHz QPOs. We find that the inner radius of the accretion disc deduced from the frequency of the upper kHz QPO varies as a function of the position of the source in the colour-colour diagram, in accordance with previous work and with the standard scenario of accretion disc geometry. On the contrary, the inner disc radius deduced from the profile of the Fe line is not correlated with the spectral state of the source. The values of the inner radius inferred from kHz QPOs and Fe lines, in four observations, do not lead to a consistent value of the neutron star mass, regardless of the model used to fit the Fe line. Our results suggest that either the kHz QPO or the standard relativistic Fe line interpretation does not apply for this system. Furthermore, the simultaneous detection of kHz QPOs and broad Fe lines is difficult to reconcile with models in which the broadening of the Fe line is due to the reprocessing of photons in an outflowing wind.Comment: 12 pages, 6 figures, Accepted for publication in MNRA

The Ethical Treatment of Research Assistants: Are We Forsaking Safety for Science?

Science inevitably involves ethical discussions about how research should be implemented. However such discussions often neglect the potential unethical treatment of a third party: the research assistant. Extensive anecdotal evidence suggests that research assistants can experience unique physical, psychological, and social risks when implementing their typical responsibilities. Moreover, these research assistants, who perhaps engage in research experience to bolster their curricula vitae, may feel coerced to continue to work in unsafe environments out of fear of losing rapport with the research supervisor or letters of recommendation for their future endeavors. In the present article, we address two important issues regarding the ethical treatment of research assistants. First, we present evidence suggesting that research assistants may experience substantive risk when implementing their assigned responsibilities. Second, we propose a document, the "Research Assistant's Bill of Rights," as a possible ethics code for people supervising research assistants. This document is independent from typical institutional review board processes, and it has the potential to maximize benefits to research supervisors and research assistants

AIS: A nonlinear activation function for industrial safety engineering

In the task of Chinese named entity recognition based on deep learning, activation function plays an irreplaceable role, it introduces nonlinear characteristics into neural network, so that the fitted model can be applied to various tasks. However, the information density of industrial safety analysis text is relatively high, and the correlation and similarity between the information are large, which is easy to cause the problem of high deviation and high standard deviation of the model, no specific activation function has been designed in previous studies, and the traditional activation function has the problems of gradient vanishing and negative region, which also lead to the recognition accuracy of the model can not be further improved. To solve these problems, a novel activation function AIS is proposed in this paper. AIS is an activation function applied in industrial safety engineering, which is composed of two piecewise nonlinear functions. In the positive region, the structure combining exponential function and quadratic function is used to alleviate the problem of deviation and standard deviation, and the linear function is added to modify it, which makes the whole activation function smoother and overcomes the problem of gradient vanishing. In the negative region, the cubic function structure is used to solve the negative region problem and accelerate the convergence of the model. Based on the deep learning model of BERT-BiLSTM-CRF, the performance of AIS is evaluated. The results show that, compared with other activation functions, AIS overcomes the problems of gradient vanishing and negative region, reduces the deviation of the model, speeds up the model fitting, and improves the extraction ability of the model for industrial entities

The Analysis of Gravity on Tourism Resource of Shijiazhuang with Anion, Hebei

AbstractThis paper analyzes the decisive factor of The Shijiazhuang coastal economic zone's tourist resource from the perspective of the actual data by adopting Gravity model; meanwhile, presents an overall aspect of Shijiazhuang city, its current development of the tourism industry, and the advantages and characteristics as well. Further proposal is also produced to contribute to the tourist development based on the analysis of the model data

The large grey area between ‘bona fide’ and ‘rogue’ stem cell interventions — ethical acceptability and the need to include local variability

This article aims to put into perspective the binary opposition between ‘scientific’ clinical research trials and ‘rogue’ experimental stem cell therapies, and to show why the ethics criteria used by the dominant science community are not suitable for distinguishing between adequate and inadequate treatments. By focusing on the grey area between clinical stem cell trials and stem cell experimentation, the experimental space where patients, medical professionals and life scientists negotiate for diverging reasons and aims, I show why idealised notions of ethics are not feasible for many stem cell scientists in low- and middle-income countries. Drawing on fieldwork in China from 2012 to 2013, the article asks why ‘the unethical’ according to some is acceptable to Chinese life scientists. The case study of stem cell service provider Beike Biotech illustrates how stem cell interventions take place in a large grey area, where narrow notions of ethics are blurred with and supplanted by broader notions of ethics, co-determined by estimations of socio-economic, political and cultural understandings of risk, opportunity and benefit. I borrow the term ‘bionetworking’, understood as the entrepreneurial aspects of scientific networks that engage in creating biomedical products, to analyse various forms of medical experimentation. I speak of the ‘externalisation’ and ‘internalisation’ of local factors to elucidate how features of patient populations and their environments are subsumed in clinical research applications. Compared to polarised views of stem cell therapy, this approach increases the transparency of clinical interventions and broadens our understanding of why ‘stem cell tourism’ to some is ‘stem cell therapy’ to others

Lufttäthet hos Veidekke - En undersökning av nuvarande lufttäthetsarbete samt förslag till förbättringar.

Abstract To build airtight buildings is something that is becoming increasingly important for operators in the construction industry. As stricter demands on airtightness and lower energy consumption are required This airtight project addresses two aspects of the construction for the success of air sealing. Partly which methods to use to get a building airtight but also what utilities have been developed to facilitate this work. The second part of this report is about how an organization can work to secure its airtightness. The work is performed in collaboration with Veidekke Construction region South Helsingborg and Division of building physics at Lund University. Conclusions to be drawn from the project: · Today they have a functioning organization that produces airtight buildings according to customer requirements. The airtight work is somewhat resource inefficient. · An existing manual, ByggaL is available today in order to facilitate the work of air tightness but it is to diffuse to be used straight off. · If you have a functioning process for its air tightness work is achieved more easily a good result. The most important thing is to have a clear division of responsibilities and demands on the various components of the construction process as design and production. · It is mainly the performance of the airtight layer that determines how airtight the building becomes. There are tools to help establish the membrane, but these do not constitute a guarantee for achieving good results. · To detect and correct any deficiencies in the early stage of construction, every project should perform an early leak. · To achieve good airtightness required competent constructors. A good constructor should be able to avoid difficult solutions while also but accurately describe how to solve a detail in order to maintain good airtightness. At the end of this report recommendations are made on topics for further work. Keywords: Airtightness, air sealing, joints, penetrations, energy, moisture, air forces, climate-peel, early leak detection, pressure testing, quality assurance air tightnes

Bridging Modeling and Certification to Evaluate Low-ILUC-Risk Practices for Biobased Materials with a User-Friendly Tool

Biobased materials may help to achieve a renewable, circular economy, but their impact could be similar to those of non-renewable materials. In the case of biofuels, the indirect land use change (ILUC) effects determine whether they can provide sustainability benefits compared to fossil fuels. ILUC modeling estimates have large uncertainties, making them difficult to include in a policy aiming at reducing environmental impacts. The Renewable Energy Directive (RED) II reduced ILUC estimate uncertainties by shifting the focus from ILUC environmental impacts to ILUC risk. Nevertheless, this does not take into account either certifiable additionality practices to reduce the ILUC risk for the production of biobased materials, or biobased materials other than biofuels. Here we propose a simple, user-friendly tool to bridge the gap between ILUC modeling and policy, by estimating the ILUC risk of biobased material production and to assess by how much different additionality practices can reduce that risk at different levels of the value chain. This was done by explicitly including the additionality practices in an ILUC model, simplifying the model to a spreadsheet tool that relates automatically the input provided by the user, which may be a producer or a policy maker, with a certain ILUC risk. We demonstrate the functioning of the tool on two examples: maize production in Iowa and in Romania. In Iowa, maize production is already very intensive, so the additionality practices proposed have little effect on its ILUC risk category, and the low-ILUC-risk-produced maize would amount to 0.03 t ha−1 year−1. In Romania there is ample margin for implementation of additionality practices, and thus a large potential to reduce the ILUC risk category of maize production, with low-ILUC-risk-produced maize amounting to 0.19 t ha−1 year −1

What We Regret Most Are Lost Opportunities: A Theory of Regret Intensity

A recent theory (Roese & Summerville, 2005) has suggested that regret is intensified by perceptions of future opportunity. In this work, however, it is proposed that feelings of regret are more likely elicited by perceptions of lost opportunity: People regret outcomes that could have been changed in the past but can no longer be changed and for which people experience low psychological closure. Consistent with the lost opportunity principle, Study 1 revealed that regretted experiences in the most commonly regretted life domains are perceived as offering the least opportunity for improvement in the future, Study 2 indicated that people experience the most regret for outcomes that are not repeatable, and Study 3 revealed that perceptions of higher past than future opportunities and low psychological closure predict regret intensity. Discussion focuses on the hope inducing yet ephemeral nature of perceived future opportunity and on the relationship between dissonance reduction and closure