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"Barrett, Jim"
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Formation of the first three gravitational-wave observations through isolated binary evolution
During its first four months of taking data, Advanced LIGO has detected gravitational waves from two binary black hole mergers, GW150914 and GW151226, along with the statistically less significant binary black hole merger candidate LVT151012. Here we use the rapid binary population synthesis code COMPAS to show that all three events can be explained by a single evolutionary channel—classical isolated binary evolution via mass transfer including a common envelope phase. We show all three events could have formed in low-metallicity environments (
Z
=0.001) from progenitor binaries with typical total masses ≳160
M
⊙
, ≳60
M
⊙
and ≳90
M
⊙
, for GW150914, GW151226 and LVT151012, respectively.
Advanced LIGO has detected gravitational waves from two binary black hole mergers, plus a merger candidate. Here the authors use the COMPAS code to show that all three events can be explained by a single evolutionary channel via a common envelope phase, and characterize the progenitor metallicity and masses.
Journal Article
Rapid Stellar and Binary Population Synthesis with COMPAS
Compact Object Mergers: Population Astrophysics and Statistics (COMPAS; https://compas.science) is a public rapid binary population synthesis code. COMPAS generates populations of isolated stellar binaries under a set of parameterized assumptions in order to allow comparisons against observational data sets, such as those coming from gravitational-wave observations of merging compact remnants. It includes a number of tools for population processing in addition to the core binary evolution components. COMPAS is publicly available via the GitHub repository https://github.com/TeamCOMPAS/COMPAS/, and is designed to allow for flexible modifications as evolutionary models improve. This paper describes the methodology and implementation of COMPAS. It is a living document that will be updated as new features are added to COMPAS; the current document describes COMPAS v02.21.00.
Journal Article
Global safety monitoring of COVID-19 vaccines: how pharmacovigilance rose to the challenge
Pharmacovigilance (PV) came suddenly into the spotlight when several new vaccines, developed as a response to the COVID-19 pandemic, received emergency authorisation and were rolled out on a large scale in late 2020. The vaccines underwent stringent clinical trials and evaluation from regulatory authorities, but with the use of novel technology and an anticipated rapid and vast deployment of the vaccines, the importance of a well-functioning international post marketing safety surveillance system was stressed. International PV stakeholders were faced with several challenges due to the extent of the global vaccination campaign. The unprecedented volume of reports of suspected adverse events following immunization has led to the development and use of new tools. Furthermore, the collaboration between various PV stakeholders was encouraged and strengthened. PV rose to the challenges posed by the currently ongoing global COVID-19 vaccination campaign and successful adaptations were made in a short period of time. However, the pandemic has not ended yet, the vaccination campaign is far from being completed, and further challenges are anticipated. Advances made during the pandemic will be important to strengthen PV in future and ensure to advance medicines’ safety together.
Plain Language Summary
Global safety monitoring of the COVID-19 vaccines: challenges, preparations, and outlooks
Pharmacovigilance (PV) is the umbrella term for all sciences and activities relating to the detection, assessment, understanding, and prevention of adverse effects relating to medicines or vaccines. PV came into the spotlight when several new vaccines were authorised and rolled out as a response to the COVID-19 pandemic.
The anticipated extent of the global vaccine rollout stressed the importance of a well-functioning safety surveillance system and international collaborations between patients, health care workers, vaccine producers, regulatory authorities, and PV centres.
The identification and communication of potential safety concerns showed that adaptations to PV processes made in a short period of time as well as international collaborations were successful. However, it is important to learn from experiences made so far and to make sure the positive advances are maintained in the future to advance medicines’ safety together.
Journal Article
An Improved Method for Identifying Duplicates in Global Databases of Adverse Event Reports for Medicines and Vaccines
Methods: A set of 1907 pairs of reports in VigiBase were annotated as either duplicates or indeterminate/non-duplicates. They were divided into subsets for training, validation, and testing, with 60%, 30% and 10% of the pairs respectively. vigiMatch2024, which builds upon the earlier version of vigiMatch (3) in routine use for reports on drugs in VigiBase, hereafter called vigiMatch2017, introduces several improvements, including: • A joint representation of all drug and adverse event start and end dates, and dates identified from the narrative. • Consideration of country specific, instead of global, drug and adverse event reporting frequencies. • Support vector machine (SVM) models (4) to balance different types of evidence of duplication. Fixed length feature vectors representing these and other evidence for and against duplication for each pair were used to train two SVM models, one specializing in vaccine reports and the other in drug reports.Performance of the models was assessed using reference datasets of known duplicates provided by national centers (US FDA, Netherlands LAREB, Spain AEMPS) together with the test dataset described above. The precision of the models was tested by having them make predictions for random pairs until they had each classified 100 pairs as duplicates. These were then validated by a human annotator, and the number of true positives used to compute the precision. The number of random pairs required to reach 100 predicted duplicates differed between the models and the number of true positives found per classified pair can be used as a proxy for each model's relative recall. Results: vigiMatch2024 outperformed or equalled the performance of vigiMatch2017 for every metric. Detailed results are presented in the table below. Conclusion: vigiMatch2024 significantly improves performance for automatically detecting duplicates in databases of adverse event reports, including for vaccines.
Journal Article
Exploring the Parameter Space of Compact Binary Population Synthesis
As we enter the era of gravitational wave astronomy, we are beginning to collect observations which will enable us to explore aspects of astrophysics of massive stellar binaries which were previously beyond reach. In this paper we describe COMPAS (Compact Object Mergers: Population Astrophysics and Statistics), a new platform to allow us to deepen our understanding of isolated binary evolution and the formation of gravitational-wave sources. We describe the computational challenges associated with their exploration, and present preliminary results on overcoming them using Gaussian process regression as a simulation emulation technique.
Journal Article
The Complete Personality Assessment
The Complete Personality Assessment provides numerous tests and self-assessment exercises to reveal not only who we are right now, but what we can do and where we can go as individuals and in our working lives.
eBook
Education for Reform
[...]we find within the traditional training paradigm an increasing component of what has become known as \"professional military education. [...]military education reform is, as it must be, an Armenian-directed project, with Western encouragement and support.
Journal Article
Ultimate aptitude tests
Recruitment, selection and assessment procedures sometimes make use of aptitude tests, which are designed to measure one’s potential for achievement. The Ultimate Aptitude Book includes verbal, numerical, perceptual and practical tests as well as exercises testing specific aptitudes such as memory and dexterity. It also covers personality and motivational tests, which assess leadership, management and social awareness aptitudes. This book is valuable for anyone who wants to see how their own unique aptitudes might best be used in a wide range of careers. For those people already in a career, it can show them how to develop their existing role as well as guide them toward a possible change of direction.
eBook