A compact instrument for gamma-ray burst detection on a CubeSat platform II: Detailed design, assembly and validation.

The Gamma-ray Module, GMOD, is a miniaturised novel gamma-ray detector which will be the primary scientific payload on the Educational Irish Research Satellite (EIRSAT-1) 2U CubeSat mission. GMOD comprises a compact (25 mm × 25 mm × 40 mm) cerium bromide scintillator coupled to a tiled array of 4 × 4 silicon photomultipliers, with front-end readout provided by the IDE3380 SIPHRA. This paper presents the detailed GMOD design and the accommodation of the instrument within the restrictive CubeSat form factor. The electronic and mechanical interfaces are compatible with many off-the-shelf CubeSat systems and structures. The energy response of the GMOD engineering qualification model has been determined using radioactive sources, and an energy resolution of 5.4% at 662 keV has been measured. EIRSAT-1 will perform on-board processing of GMOD data. Trigger results, including light-curves and spectra, will be incorporated into the spacecraft beacon and transmitted continuously. Inexpensive hardware can be used to decode the beacon signal, making the data accessible to a wide community. GMOD will have scientific capability for the detection of gamma-ray bursts, in addition to the educational and technology demonstration goals of the EIRSAT-1 mission. The detailed design and measurements to date demonstrate the capability of GMOD in low Earth orbit, the scalability of the design for larger CubeSats and as an element of future large gamma-ray missions.

Sleep quality in patients with chronic illness.

AIMS AND OBJECTIVES: To explore sleep quality in patients with chronic illness in primary care. BACKGROUND: Many people suffer from chronic illness with the numbers increasing. One common issue arises from problems that people have with their quality of sleep: a largely under-researched topic. This study exploring poor quality sleep allowed patients to describe their daily struggles with poor sleep in their own lives. This allowed the development of a deeper understanding of what it means to sleep poorly and find out how participants cope with not sleeping well. DESIGN: A qualitative approach enabling a deep exploration of patient's experiences of sleep quality was used. Interviews were conducted with a purposive sample of nine participants from a primary care clinic. Analysis utilised an interpretative approach. RESULTS: Data analysed produced four recurrent themes that were grouped into two categories. First, themes that identified the recognition by participants that 'something was wrong' were abrupt beginning and impact on their life. Second, themes that identified that the participants considered there was 'nothing wrong' were I am fine and I just carry on. CONCLUSION: Data revealed that poor quality sleep can have a profound effect on quality of life. Participants lived without good quality sleep for years. They had come to accept two seemingly irreconcilable ideas that not being able to sleep is an enduring problem with a distinct starting point, and paradoxically, this is not a problem that deserves much professional attention. RELEVANCE TO CLINICAL PRACTICE: Important original data were generated on the impact of poor quality sleep indicating that chronically disturbed sleep can increase the disease burden on patients with chronic illness. The results of this study suggest healthcare professionals need to understand how sleep quality issues impact on patient's experience of chronic illness. Data from this study will help nurses and other health professionals to deepen their understanding of the profound impact of poor quality sleep on patients with chronic illness. A programme of education highlighting the important role of sleep quality in chronic illness is suggested by the issues raised in this study. Nurses are ideally placed to assess sleep quality in patients and tailor intervention to positively affect the quality of life for this group.

LightForce photon-pressure collision avoidance: Efficiency analysis in the current debris environment and long-term simulation perspective.

This work provides an efficiency analysis of the LightForce space debris collision avoidance scheme in the current debris environment and describes a simulation approach to assess its impact on the long-term evolution of the space debris environment. LightForce aims to provide just-in-time collision avoidance by utilizing photon pressure from ground-based industrial lasers. These ground stations impart minimal accelerations to increase the miss distance for a predicted conjunction between two objects. In the first part of this paper we will present research that investigates the short-term effect of a few systems consisting of 20 kW class lasers directed by 1.5 m diameter telescopes using adaptive optics. The results found such a network of ground stations to mitigate more than 85 percent of conjunctions and could lower the expected number of collisions in Low Earth Orbit (LEO) by an order of magnitude. While these are impressive numbers that indicate LightForce's utility in the short-term, the remaining 15 % of possible collisions contain (among others) conjunctions between two massive objects that would add large amount of debris if they collide. Still, conjunctions between massive objects and smaller objects can be mitigated. Hence, we choose to expand the capabilities of the simulation software to investigate the overall effect of a network of LightForce stations on the long-term debris evolution. In the second part of this paper, we will present the planned simulation approach for that effort. For the efficiency analysis of collision avoidance in the current debris environment, we utilize a simulation approach that uses the entire Two Line Element (TLE) catalog in LEO for a given day as initial input. These objects are propagated for one year and an all-on-all conjunction analysis is performed. For conjunctions that fall below a range threshold, we calculate the probability of collision and record those values. To assess efficiency, we compare a baseline (without collision avoidance) conjunction analysis with an analysis where LightForce is active. Using that approach, we take into account that collision avoidance maneuvers could have effects on third objects. Performing all-on-all conjunction analyses for extended period of time requires significant computer resources; hence we implemented this simulation utilizing a highly parallel approach on the NASA Pleiades supercomputer.