An active nutation damper for spacecraft

An active nutation damping device, consisting of an angular accelerometer, a dc-motor-driven flywheel, and associated electronics, developed for spacecraft use is described. This damping system was used on the LAGEOS spacecraft to control nutation buildup during the long coast period (approximately 75 minutes) after the third stage separation. The damper package was evaluated and proven on a three-axis gas-bearing simulator that duplicated the LAGEOS spacecraft critical flight dynamics. In addition, a failure analysis of the damper assembly was performed. Performance of the damper during the LAGEOS flight has confirmed the preflight evaluation and analysis

MOS field-effect-transistor technology

Metal oxide semiconductor field effect transistor circuit development and laminated electronic packaging for computer storage device

An Earth Albedo Model: A Mathematical Model for the Radiant Energy Input to an Orbiting Spacecraft Due to the Diffuse Reflectance of Solar Radiation from the Earth Below

Past missions have shown that the earth's albedo can have a significant effect on the sun sensors used for spacecraft attitude control information. In response to this concern, an algorithm was developed to simulate this phenomenon, consisting of two parts, the physical model of albedo and its effect on the sun sensors. This paper contains the theoretical development of this model, practical operational notes, and its implementation in a FORTRAN subroutine

Testing of the on-board attitude determination and control algorithms for SAMPEX

Algorithms for on-board attitude determination and control of the Solar, Anomalous, and Magnetospheric Particle Explorer (SAMPEX) have been expanded to include a constant gain Kalman filter for the spacecraft angular momentum, pulse width modulation for the reaction wheel command, an algorithm to avoid pointing the Heavy Ion Large Telescope (HILT) instrument boresight along the spacecraft velocity vector, and the addition of digital sun sensor (DSS) failure detection logic. These improved algorithms were tested in a closed-loop environment for three orbit geometries, one with the sun perpendicular to the orbit plane, and two with the sun near the orbit plane - at Autumnal Equinox and at Winter Solstice. The closed-loop simulator was enhanced and used as a truth model for the control systems' performance evaluation and sensor/actuator contingency analysis. The simulations were performed on a VAX 8830 using a prototype version of the on-board software

A magnetic hysteresis model

The Passive Aerodynamically Stabilized Magnetically Damped Satellite (PAMS) will be deployed from the Space Shuttle and used as a target for a Shuttle-mounted laser. It will be a cylindrical satellite with several corner cube reflectors on the ends. The center of mass of the cylinder will be near one end, and aerodynamic torques will tend to align the axis of the cylinder with the spacecraft velocity vector. Magnetic hysteresis rods will be used to provide passive despin and oscillation-damping torques on the cylinder. The behavior of the hysteresis rods depends critically on the 'B/H' curves for the combination of materials and rod length-to-diameter ratio ('l-over-d'). These curves are qualitatively described in most Physics textbooks in terms of major and minor 'hysteresis loops'. Mathematical modeling of the functional relationship between B and H is very difficult. In this paper, the physics involved is not addressed, but an algorithm is developed which provides a close approximation to empirically determined data with a few simple equations suitable for use in computer simulations

MIDEX Advanced Modular and Distributed Spacecraft Avionics Architecture

MIDEX (Medium Class Explorer) is the newest line in NASA's Explorer spacecraft development program. As part of the MIDEX charter, the MIDEX spacecraft development team has developed a new modular, distributed, and scaleable spacecraft architecture that pioneers new spaceflight technologies and implementation approaches, all designed to reduce overall spacecraft cost while increasing overall functional capability. This resultant "plug and play" system dramatically decreases the complexity and duration of spacecraft integration and test, providing a basic framework that supports spacecraft modularity and scalability for missions of varying size and complexity. Together, these subsystems form a modular, flexible avionics suite that can be modified and expanded to support low-end and very high-end mission requirements with a minimum of redesign, as well as allowing a smooth, continuous infusion of new technologies as they are developed without redesigning the system. This overall approach has the net benefit of allowing a greater portion of the overall mission budget to be allocated to mission science instead of a spacecraft bus. The MIDEX scaleable architecture is currently being manufactured and tested for use on the Microwave Anisotropy Probe (MAP), an inhouse program at GSFC

A method to implement fine-grained access control for personal health records through standard relational database queries

AbstractOnline personal health records (PHRs) enable patients to access, manage, and share certain of their own health information electronically. This capability creates the need for precise access-controls mechanisms that restrict the sharing of data to that intended by the patient. The authors describe the design and implementation of an access-control mechanism for PHR repositories that is modeled on the eXtensible Access Control Markup Language (XACML) standard, but intended to reduce the cognitive and computational complexity of XACML. The authors implemented the mechanism entirely in a relational database system using ANSI-standard SQL statements. Based on a set of access-control rules encoded as relational table rows, the mechanism determines via a single SQL query whether a user who accesses patient data from a specific application is authorized to perform a requested operation on a specified data object. Testing of this query on a moderately large database has demonstrated execution times consistently below 100ms. The authors include the details of the implementation, including algorithms, examples, and a test database as Supplementary materials

A Serpin shapes the extracellular environment to prevent influenza A virus maturation

Interferon-stimulated genes (ISGs) act in concert to provide a tight barrier against viruses. Recent studies have shed light on the contribution of individual ISG effectors to the antiviral state, but most have examined those acting on early, intracellular stages of the viral life cycle. Here, we applied an image-based screen to identify ISGs inhibiting late stages of influenza A virus (IAV) infection. We unraveled a directly antiviral function for the gene SERPINE1, encoding plasminogen activator inhibitor 1 (PAI-1). By targeting extracellular airway proteases, PAI-1 inhibits IAV glycoprotein cleavage, thereby reducing infectivity of progeny viruses. This was biologically relevant for IAV restriction in vivo. Further, partial PAI-1 deficiency, attributable to a polymorphism in human SERPINE1, conferred increased susceptibility to IAV in vitro. Together, our findings reveal that manipulating the extracellular environment to inhibit the last step in a virus life cycle is an important mechanism of the antiviral response

The need for early referral to palliative care especially for Black, Asian and minority ethnic groups in a COVID-19 pandemic:Findings from a service evaluation

Background: Palliative care services face challenges in adapting and responding to the COVID-19 pandemic. Understanding how palliative care needs and outcomes have changed during the pandemic compared to before the pandemic is crucial to inform service planning and research initiatives. Aim: To evaluate the impact of COVID-19 on symptoms, clinical characteristics, and outcomes for patients referred to a hospital-based palliative care service in a district general hospital in London, UK. Design: A retrospective service evaluation. Data were extracted from the electronic patient records. Setting/participants: The first 60 inpatients with confirmed COVID-19 infection, referred to the hospital palliative care service between 1 March 2020 and 23 April 2020, and another 60 inpatients, referred to the hospital palliative care service between 11 March 2019 and 23 April 2019, were included from a district general hospital in East London, UK. Results: Patients with COVID-19 have lower comorbidity scores, poorer performance status, and a shorter time from referral to death compared to patients without COVID-19. Breathlessness, drowsiness, agitation, and fever are the most prevalent symptoms during COVID-19 compared to pain and drowsiness pre-COVID-19. Time from admission to referral to palliative care is longer for Black, Asian and minority ethnic patients, especially during COVID-19. Conclusion: Early referral to palliative care is essential in COVID-19, especially for Black, Asian and minority ethnic groups. There is urgent need to research why Black, Asian and minority ethnic patients are referred late; how palliative care services have changed; and possible solutions to setting up responsive, flexible, and integrated services

Adult Social Work and High Risk Domestic Violence Cases

Summary This article focuses on adult social work’s response in England to high-risk domestic violence cases and the role of adult social workers in Multi-Agency Risk and Assessment Conferences. (MARACs). The research was undertaken between 2013-2014 and focused on one city in England and involved the research team attending MARACs, Interviews with 20 adult social workers, 24 MARAC attendees, 14 adult service users at time T1 (including follow up interviews after six months, T2), focus groups with IDVAs and Women’s Aid and an interview with a Women’s Aid service user. Findings The findings suggest that although adult social workers accept the need to be involved in domestic violence cases they are uncertain of what their role is and are confused with the need to operate a parallel domestic violence and adult safeguarding approach, which is further, complicated by issues of mental capacity. MARACS are identified as overburdened, under-represented meetings staffed by committed managers. However, they are in danger of becoming managerial processes neglecting the service users they are meant to protect. Applications The article argues for a re-engagement of adult social workers with domestic violence that has increasingly become over identified with child protection. It also raises the issue whether MARACS remain fit for purpose and whether they still represent the best possible response to multi-agency coordination and practice in domestic violence