Efficient SmallSat Operation Using SciBox

Planning and commanding a space operation is inherently a very complex task requiring highly skilled operators from various disciplines coordinating in a timely manner to ensure both smooth and successful operation. This process can be performed manually, however, resolving conflicts quickly becomes an intensive iterative process that underuses a space system’s resources and renders it less responsive to sudden schedule changes. Increasingly complex space missions combined with the desire to maximize efficiency require a different approach. Responding to these challenges is SciBox, an autonomous planning and commanding system and a technology enabler for space operations, developed by the Johns Hopkins University Applied Physics Laboratory (APL). Since its development in 2001, SciBox has automated the processes of translating user requests into a series of satellite operations, searching for observation and data collection opportunities, scheduling required resources and contact with ground stations, generating command sequences to drive payloads and spacecraft, and validating the generated command sequences against operational health and safety constraints. Continual improvements to SciBox and to the SciBox development process through its application on a number of APL small sat missions will be discussed in this paper. The initial use of SciBox for small sat operations was on the ORS Tech 1 and ORS Tech 2 Multi-mission Bus Demonstration (MBD) program. This program required an easy-to-use, operational management system for use by a non-APL operations team. This instantiation of the SciBox was named S2Ops. With a user-friendly, graphics interface built, this version of SciBox was an ideal solution for the government operations team. For the CubeSat Signal Preprocessor Assessment and Test (CAT) mission, APL operates two 3U satellites, each hosting an industry-provided RF instrument, in low Earth orbit (LEO). APL operates the satellites using SciBox, which provides key features to autonomously manage satellite constellations. Given the limited operational resources and the desire to maximize the number of experiments performed, SciBox is an ideal solution for the CAT mission. SciBox reduces the lead time for operations planning by shortening the time-consuming coordination process, reduces cost by automating the labor-intensive processes of human-in-the-loop adjudication of operational priorities, reduces operations risk by systematically checking mission constraints, and maximizes data return by fully evaluating the trade space of experimental opportunities versus spacecraft recorder, downlink, scheduling, and orbital-geometry constraints. SciBox is also used on CAT to generate a command schedule that executes the following operations: South Atlantic Anomaly (SAA) constraints, experiment configuration schedule, ground station contacts, delta-differential drag maneuvers, and flight safety constraints. Finally, the latest application of SciBox is to the Electrojet Zeeman Imaging Explorer (EZIE) mission, which studies the electric currents that play a crucial role in the interactions between Earth and the surrounding magnetosphere. EZIE consists of three 6U CubeSats flying in a pearls-on-a-string orbit configuration, each carrying a Microwave Electrojet Magnetogram (MEM) instrument. This mission will utilize the SciBox capabilities demonstrated on CAT, but also include enhanced features such as early spacecraft recovery by using the observed carrier frequency (or Doppler shift), and support the systems integration phase prior to launch

Validation of the World Health Organization Tool for Situational Analysis to Assess Emergency and Essential Surgical Care at District Hospitals in Ghana

The World Health Organization (WHO) Tool for Situational Analysis to Assess Emergency and Essential Surgical Care (hereafter called the WHO Tool) has been used in more than 25 countries and is the largest effort to assess surgical care in the world. However, it has not yet been independently validated. Test–retest reliability is one way to validate the degree to which tests instruments are free from random error. The aim of the present field study was to determine the test–retest reliability of the WHO Tool. The WHO Tool was mailed to 10 district hospitals in Ghana. Written instructions were provided along with a letter from the Ghana Health Services requesting the hospital administrator to complete the survey tool. After ensuring delivery and completion of the forms, the study team readministered the WHO Tool at the time of an on-site visit less than 1 month later. The results of the two tests were compared to calculate kappa statistics for each of the 152 questions in the WHO Tool. The kappa statistic is a statistical measure of the degree of agreement above what would be expected based on chance alone. Ten hospitals were surveyed twice over a short interval (i.e., less than 1 month). Weighted and unweighted kappa statistics were calculated for 152 questions. The median unweighted kappa for the entire survey was 0.43 (interquartile range 0–0.84). The infrastructure section (24 questions) had a median kappa of 0.81; the human resources section (13 questions) had a median kappa of 0.77; the surgical procedures section (67 questions) had a median kappa of 0.00; and the emergency surgical equipment section (48 questions) had a median kappa of 0.81. Hospital capacity survey questions related to infrastructure characteristics had high reliability. However, questions related to process of care had poor reliability and may benefit from supplemental data gathered by direct observation. Limitations to the study include the small sample size: 10 district hospitals in a single country. Consistent and high correlations calculated from the field testing within the present analysis suggest that the WHO Tool for Situational Analysis is a reliable tool where it measures structure and setting, but it should be revised for measuring process of care

ATRX Partners with Cohesin and MeCP2 and Contributes to Developmental Silencing of Imprinted Genes in the Brain

Human developmental disorders caused by chromatin dysfunction often display overlapping clinical manifestations, such as cognitive deficits, but the underlying molecular links are poorly defined. Here, we show that ATRX, MeCP2, and cohesin, chromatin regulators implicated in ATR-X, RTT, and CdLS syndromes, respectively, interact in the brain and colocalize at the H19 imprinting control region (ICR) with preferential binding on the maternal allele. Importantly, we show that ATRX loss of function alters enrichment of cohesin, CTCF, and histone modifications at the H19 ICR, without affecting DNA methylation on the paternal allele. ATRX also affects cohesin, CTCF, and MeCP2 occupancy within the Gtl2/Dlk1 imprinted domain. Finally, we show that loss of ATRX interferes with the postnatal silencing of the maternal H19 gene along with a larger network of imprinted genes. We propose that ATRX, cohesin, and MeCP2 cooperate to silence a subset of imprinted genes in the postnatal mouse brain