Planning and Design Considerations for Computer Supported Collaboration Spaces

Architects have long been aware of the need to design for the behaviors a space is meant to support. However, neither the seminal works on architectural programming or collaborative engineering address the linkages between physical environment design and collaborative work practice. This paper posits that the design of collaboration environments should stand as a third pillar of collaboration engineering, suggests four ways in which physical environment design and collaboration engineering might mutually inform the other, and specifies several dimensions of physical environment affordance collaboration engineers might consider when developing requirements for collaboration space

Atomic Resonance and Scattering

Contains reports on eight research projects.National Science Foundation (Grant PHY77-09155)Joint Services Electronics Program (Contract DAAG29-78-C-0020)U. S. Department of Energy (Grant EG-77-S-02-4370)National Science Foundation (Grant DMR 77-10084)National Aeronautics and Space Administration (Grant NSG-1551)U. S. Air Force - Office of Scientific Research (Grant AFOSR-76-2972)National Science Foundation (Grant CHE76-81750

Environmental Noise in Advanced LIGO Detectors

The sensitivity of the Advanced LIGO detectors to gravitational waves can be affected by environmental disturbances external to the detectors themselves. Since the transition from the former initial LIGO phase, many improvements have been made to the equipment and techniques used to investigate these environmental effects. These methods have aided in tracking down and mitigating noise sources throughout the first three observing runs of the advanced detector era, keeping the ambient contribution of environmental noise below the background noise levels of the detectors. In this paper we describe the methods used and how they have led to the mitigation of noise sources, the role that environmental monitoring has played in the validation of gravitational wave events, and plans for future observing runs

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

Planning and Design Considerations for Computer Supported Collaboration Spaces

Architects have long been aware of the need to design for the behaviors a space is meant to support. However, neither the seminal works on architectural programming or collaborative engineering address the linkages between physical environment design and collaborative work practice. This paper posits that the design of collaboration environments should stand as a third pillar of collaboration engineering, suggests four ways in which physical environment design and collaboration engineering might mutually inform the other, and specifies several dimensions of physical environment affordance collaboration engineers might consider when developing requirements for collaboration space

Spectroscopic Imaging using Terahertz Time-Domain Signals

Conference PaperImaging systems based on terahertz time-domain spectroscopy offer a range of unique modalities due to the broad bandwidth, sub-picosecond duration, and phase-sensitive detection of the terahertz pulses. Furthermore, an exciting possibility exists to combine spectroscopic characterization and/or identification with imaging because the radiation is broadband in nature. In order to achieve this, novel methods for real-time analysis of terahertz waveforms are required. Unfortunately, both the absorption and the phase delay of a transmitted terahertz pulse vary exponentially with the sample's thickness. We describe a robust algorithm for extracting both the thickness and the complex index of refraction of an unknown sample. In contrast, most spectroscopic transmission measurements require accurate knowledge of the sample's thickness to determine the optical parameters. We also investigate the limits of our method