Multi-messenger observations of a binary neutron star merger

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta

Development of meaning making:A dynamic systems approach

The development of meaning making can be seen as a central aspect of the development of self and identity in adolescence and adulthood. Current theories in this area offer descriptions of different developmental stages, but little is known about the factors and mechanisms involved in the developmental process. In this article a conceptual model is presented of these factors and mechanisms, Because descriptive models are too general to permit detailed descriptions of the process or the formulation of specific hypotheses for the validation of the model, the model has been translated into a quantitative dynamic systems model which allows the developmental process to be simulated. The developmental trajectories generated by the model can be compared with the theoretical ideas and empirical data concerning the development of meaning making. The simulated trajectories of the development of meaning making show a good fit with both the theory and the available data. This means that the assumptions about the factors and mechanisms in the developmental process on which the model has been based have at least some validity. In addition, the simulations generate new hypotheses about the process. It is concluded that quantitative dynamic systems models offer a useful way of exploring the validity of theoretical notions about developmental processes. (C) 2000 Elsevier Science Ltd. All rights reserved

Determinants and mechanisms in ego identity development:A review and synthesis

The literature concerning the determinants and mechanisms of ego identity development is scattered and diverse. This article offers a review of this literature from different fields in the social sciences. Following a review, an attempt is made to integrate the ideas offered in the literature into an encompassing model of the process of identity development. The model describes identity development as an iterative process of person-context transactions. Conflicts arising in the course of these transactions are considered to trigger off development. The developmental trajectory is determined by the way in which these conflicts are solved. Optimal development requires a good balance between assimilation and accommodation of a person's commitments. Important determinants in this process are factors that enhance openness to change, environmental support, and the developmental history. (C) 2001 Academic Press

Stability and change in emotion-organization

This investigation is based on the assumption that a person's emotion-organization is a stable, idiosyncratic property of great importance in determining that person's distinctive characteristics. The two main issues are whether a stable emotion-organization can be found in the turmoil of everyday life and whether life events affect this organization. A sequence of 323 daily assessments of an emotion list by a 26-year-old woman justifies the conclusion that stable, meaningful clusters of emotions can be distinguished. Highly emotional events have an enduring effect upon the organization of these clusters