Vsini-s for late-type stars from spectral synthesis in K-band region

We analyse medium-resolution spectra (R\sim 18000) of 19 late type dwarfs in order to determine vsini-s using synthetic rather than observational template spectra. For this purpose observational data around 2.2 $\mu$m of stars with spectral classes from G8V to M9.5V were modelled. We find that the Na I (2.2062 and 2.2090 $\mu$m) and $^{12}$CO 2-0 band features are modelled well enough to use for vsini determination without the need for a suitable observational template spectra. Within the limit of the resolution of our spectra, we use synthetic spectra templates to derive vsini values consistent with those derived in the optical regime using observed templates. We quantify the errors in our vsini determination due to incorrect choice of model parameters \Teff, log $g$, $v_{\rm micro}$, [Fe/H] or FWHM and show that they are typically less than 10 per cent. We note that the spectral resolution of our data(\sim 16 km/s) limited this study to relatively fast rotators and that resolutions of 60000 will required to access most late-type dwarfs.Comment: 8 pages, 4 figures, 3 tables, accepted to the MNRA

Binary frequency of planet-host stars at wide separations: A new brown dwarf companion to a planet-host star

The aim of the project is to improve our knowledge on the multiplicity of planet-host stars at wide physical separations. We cross-matched approximately 6200 square degree area of the Southern sky imaged by the Visible Infrared Survey Telescope for Astronomy (VISTA) Hemisphere Survey (VHS) with the Two Micron All Sky Survey (2MASS) to look for wide common proper motion companions to known planet-host stars. We complemented our astrometric search with photometric criteria. We confirmed spectroscopically the co-moving nature of seven sources out of 16 companion candidates and discarded eight, while the remaining one stays as a candidate. Among these new wide companions to planet-host stars, we discovered a T4.5 dwarf companion at 6.3 arcmin (~9000 au) from HIP70849, a K7V star which hosts a 9 Jupiter mass planet with an eccentric orbit. We also report two new stellar M dwarf companions to one G and one metal-rich K star. We infer stellar and substellar binary frequencies for our complete sample of 37 targets of 5.4+/-3.8% and 2.7+/-2.7% (1 sigma confidence level), respectively, for projected physical separations larger than ~60-160 au assuming the range of distances of planet-host stars (24-75 pc). These values are comparable to the frequencies of non planet-host stars. We find that the period-eccentricity trend holds with a lack of multiple systems with planets at large eccentricities (e > 0.2) for periods less than 40 days. However, the lack of planets more massive than 2.5 Jupiter masses and short periods (<40 days) orbiting single stars is not so obvious due to recent discoveries by ground-based transit surveys and space missions.Comment: Accepted for publication in A&A, 13 pages, 5 figures, 3 tables, optical spectra will be available at CDS Strasbour

Transitioning from a Conventional to a ‘Mega’ Journal: A Bibliometric Case Study of the Journal Medicine

Open-Access Mega-Journals (OAMJs) are a relatively new and increasingly important publishing phenomenon. The journal Medicine is in the unique position of having transitioned in 2014 from being a ‘traditional’ highly-selective journal to the OAMJ model. This study compares the bibliometric profile of the journal Medicine before and after its transition to the OAMJ model. Three standard modes of bibliometric analysis are employed, based on data from Web of Science: journal output volume, author characteristics, and citation analysis. The journal’s article output is seen to have grown hugely since its conversion to an OAMJ, a rise driven in large part by authors from China. Articles published since 2015 have fewer citations, and are cited by lower impact journals than articles published before the OAMJ transition. The adoption of the OAMJ model has completely changed the bibliometric profile of the journal, raising questions about the impact of OAMJ peer-review practices. In many respects, the post-2014 version of Medicine is best viewed as a new journal rather than a continuation of the original title

Open-access mega-journals

Purpose: Open-access mega-journals (OAMJs) represent an increasingly important part of the scholarly communication landscape. OAMJs, such as PLOS ONE, are large scale, broad scope journals that operate an open access business model (normally based on article-processing charges), and which employ a novel form of peer review, focusing on scientific ‘soundness’ and eschewing judgment of novelty or importance. This paper examines the discourses relating to OAMJs, and their place within scholarly publishing, and considers attitudes towards mega-journals within the academic community. Design/methodology/approach: This paper presents a review of the literature of OAMJs structured around four defining characteristics: scale, disciplinary scope, peer review policy and economic model. The existing scholarly literature was augmented by searches of more informal outputs, such as blogs and email discussion lists, to capture the debate in its entirety. Findings: While the academic literature relating specifically to OAMJs is relatively sparse, discussion in other fora is detailed and animated, with debates ranging from the sustainability and ethics of the mega-journal model, to the impact of soundness-only peer review on article quality and discoverability, and the potential for OAMJs to represent a paradigm-shifting development in scholarly publishing. Originality/value: This article represents the first comprehensive review of the mega-journal phenomenon, drawing not only on the published academic literature, but also grey, professional and informal sources. The paper advances a number of ways in which the role of OAMJs in the scholarly communication environment can be conceptualised

Open access megajournals: The publisher perspective (Part 2: Operational realities)

This paper is the second of two Learned Publishing articles in which we report the results of a series of interviews, with senior publishers and editors exploring open access megajournals (OAMJs). Megajournals (of which PLoS One is the best known example) represent a relatively new approach to scholarly communication and can be characterized as large, broad-scope, open access journals, which take an innovative approach to peer review, basing acceptance decisions solely on the technical or scientific soundness of the article. Based on interviews with 31 publishers and editors, this paper reports the perceived cultural, operational, and technical challenges associated with launching, growing, and maintaining a megajournal. We find that overcoming these challenges while delivering the societal benefits associated with OAMJs is seen to require significant investment in people and systems, as well as an ongoing commitment to the model

Open access megajournals: The publisher perspective (Part 1: Motivations)

This paper is the first of two Learned Publishing articles in which we report the results of a series of interviews with senior publishers and editors exploring open access megajournals (OAMJs). Megajournals (of which PLoS One is the best known example) represent a relatively new approach to scholarly communication and can be characterized as large, broad-scope, open access journals that take an innovative approach to peer review, basing acceptance decisions solely on the technical or scientific soundness of the article. This model is often said to support the broader goals of the open science movement. Based on in-depth interviews with 31 publishers and editors representing 16 different organizations (10 of which publish a megajournal), this paper reports how the term ‘megajournal’ is understood and publishers’ rationale and motivations for launching (or not launching) an OAMJ. We find that while there is general agreement on the common characteristics of megajournals, there is not yet a consensus on their relative importance. We also find seven motivating factors that were said to drive the launch of an OAMJ and link each of these factors to potential societal and business benefits. These results suggest that the often polarized debate surrounding OAMJs is a consequence of the extent to which observers perceive publishers to be motivated by these societal or business benefits

“Let the community decide”? The vision and reality of soundness-only peer review in open-access mega-journals

Purpose: The aim of this research is to better understand the theory and practice of peer review in open-access mega-journals (OAMJs). Mega-journals typically operate a “soundness only” review policy aiming to evaluate only the rigour of an article, not the novelty or significance of the research or its relevance to a particular community, with these elements being left for “the community to decide” post-publication. Design/methodology/approach: The paper reports the results of interviews with 31 senior publishers and editors representing 16 different organisations, including 10 that publish an OAMJ. Thematic Analysis was carried out on the data and an analytical model developed to explicate their significance. Findings: Findings suggest that in reality criteria beyond technical or scientific soundness can and do influence editorial decisions. Deviations from the original OAMJ model are both publisher-supported (in the form of requirements for an article to be ‘worthy’ of publication) and practice-driven (in the form of some reviewers and editors applying traditional peer review criteria to mega-journal submissions). Also publishers believe post-publication evaluation of novelty, significance, and relevance remains problematic. Originality/value: The study is based on unprecedented access to senior publishers and editors, allowing insight into their strategic and operational priorities. The paper is the first to report in-depth qualitative data relating specifically to soundness-only peer review for OAMJs, shedding new light on the mega-journal phenomenon, and helping inform discussion on its future role in scholarly communication. The paper proposes a new model for understanding the mega-journal approach to quality assurance, and how it is different from traditional peer review

Towards the digitalisation of porous energy materials: evolution of digital approaches for microstructural design

Porous energy materials are essential components of many energy devices and systems, the development of which have been long plagued by two main challenges. The first is the ‘curse of dimensionality’, i.e. the complex structure–property relationships of energy materials are largely determined by a high-dimensional parameter space. The second challenge is the low efficiency of optimisation/discovery techniques for new energy materials. Digitalisation of porous energy materials is currently being considered as one of the most promising solutions to tackle these issues by transforming all material information into the digital space using reconstruction and imaging data and fusing this with various computational methods. With the help of material digitalisation, the rapid characterisation, the prediction of properties, and the autonomous optimisation of new energy materials can be achieved by using advanced mathematical algorithms. In this paper, we review the evolution of these computational and digital approaches and their typical applications in studying various porous energy materials and devices. Particularly, we address the recent progress of artificial intelligence (AI) in porous energy materials and highlight the successful application of several deep learning methods in microstructural reconstruction and generation, property prediction, and the performance optimisation of energy materials in service. We also provide a perspective on the potential of deep learning methods in achieving autonomous optimisation and discovery of new porous energy materials based on advanced computational modelling and AI techniques

The metal rich abundance pattern - spectroscopic properties and abundances for 107 main-sequence stars

This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society, ©: 2017 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.We report results from the high resolution spectral analysis of the 107 metal rich (mostly [Fe/H]$\ge$7.67 dex) target stars from the Calan-Hertfordshire Extrasolar Planet Search program observed with HARPS. Using our procedure of finding the best fit to the absorption line profiles in the observed spectra, we measure the abundances of Na, Mg, Al, Si, Ca, Ti, Cr, Mn, Fe, Ni, Cu, and Zn, and we then compare them with known results from different authors. Most of our abundances agree with these works at the level of $\pm$0.05 dex or better for the stars we have in common. However, we do find systematic differences that make direct inferences difficult. Our analysis suggests that the selection of line lists and atomic line data along with the adopted continuum level influence these differences the most. At the same time, we confirm the positive trends of abundances versus metallicity for Na, Mn, Ni, and to a lesser degree, Al. A slight negative trend is observed for Ca, whereas Si and Cr tend to follow iron. Our analysis allows us to determine the positively skewed normal distribution of projected rotational velocities with a maximum peaking at 3 km s$^{-1}$. Finally, we obtained a Gaussian distribution of microturbulent velocities that has a maximum at 1.2 km s$^{-1}$ and a full width at half maximum $\Delta v_{1/2}=$0.35 km s$^{-1}$, indicating that metal rich dwarfs and subgiants in our sample have a very restricted range in microturbulent velocity.Peer reviewedFinal Published versio