844.6 nm photometer calibration for ground-based thermospheric oxygen density measurement

Ground-based observations of spectral emission lines are commonly used to investigate conditions in the upper atmosphere, where in-situ measurements are generally infeasible. The atomic oxygen 844.6 nm emission line is a prominent feature in the midlatitude thermosphere. Energetic photoelectron flux, radiative recombination of O+ ions, and active radio-frequency heating are known to generate 844.6 nm emission. The 844.6 nm emission line has both well-understood photochemistry and line brightness sensitivity to oxygen density. These characteristics make it a favorable candidate for oxygen density measurement in the upper thermosphere. Previously, 844.6 nm observations have been made using high resolution spectrometry and tilting filter photomultiplier tubes. However, these efforts lacked spatial data as well as absolute intensity calibration required to derive oxygen density. This thesis presents the design, calibration, and first light observations of a novel imaging photometer. The photometer will be capable of on-sky brightness calibration during routine observations from a ground-based facility. Absolute calibration of emission line brightness will advance current understanding of O 844.6 nm emission excitation sources and allow for oxygen density measurement.Ope

CubeSat Active Thermal Control via Microvascular Carbon Fiber Channel Radiator

Small spacecraft rarely have space for any thermal control subsystems and often must perform operations in “burst” mode as a result. The few spacecraft who do have control rely on low-complexity thermal control systems which conduct heat to the bus structure and then radiate the heat away. These simplistic techniques are sufficient for low power missions in Low Earth Orbit (LEO) but are not capable of dumping the heat produced in new mission profiles that are in development. This is due to small spacecraft incorporating increasingly advanced subsystems which have difficult thermal control requirements such as propulsion systems or high-power antennas. The University of Illinois at Urbana-Champaign, in partnership with NASA Ames Research Center, is developing a thermal control system for small spacecraft. This control system uses a deployable radiator panel made from carbon fiber with micro-vascular circulatory system for coolant. This paper is a follow-up on the previous year’s SmallSat conference. A bench prototype of the thermal control subsystem was designed and built. The prototype underwent a range of thermal and vibration tests at NASA Ames. Test results and lessons learned are presented. Moving forward, test conclusions will require some design parameters to be changed and the subsystem will reach TRL 6 by the end of the two-year program

Greater Reduction in Mid-treatment FDG-PET Volume May Be Associated with Worse Survival in Non-Small Cell Lung Cancer

Background and purpose: This study tested the hypotheses that 1) changes in mid-treatment fluorodeoxyglucose (FDG)-positron emission tomography (PET) parameters are predictive of overall survival (OS) and 2) mid-treatment FDG-PET-adapted treatment has the potential to improve survival in patients with non-small cell lung cancer (NSCLC). Material and methods: Patients with stage I-III NSCLC requiring daily fractionated radiation were eligible. FDG-PET-CT scans were obtained prior to and mid-treatment with radiotherapy at 40-50 Gy. The normalized maximum standardized uptake value (NSUVmax), normalized mean SUV (NSUVmean), PET-metabolic tumor volume (MTV), total lesion glycolysis (TLG), and computed tomography-based gross tumor volume (CT-GTV) were consistently measured for all patients. The primary study endpoint was OS. Results: The study is comprised of 102 patients who received 3-dimensional conformal radiotherapy, among whom 30 patients who received mid-treatment PET-adapted dose escalation radiotherapy. All PET-CT parameters decreased significantly (P 0.1). Patients receiving conventional radiation (60-70 Gy) with MTV reductions greater than the mean had a median survival of 14 months, compared to those with MTV reductions less than the mean who had a median survival of 22 months. By contrast, patients receiving mid-treatment PET-adapted radiation with MTV reductions greater than the mean had a median survival of 33 months, compared to those with MTV reductions less than the mean who had a median survival of 19 months. Overall, PET-adapted treatment resulted in a 19% better 5-year survival than conventional radiation. Conclusion: Changes in mid-treatment PET-volumetric parameters were significantly associated with survival in NSCLC. A greater reduction in the mid-treatment MTV was associated with worse survival in patients treated with standard radiation, but with better survival in patients who received mid-treatment PET-adapted treatment

APIS: Applications and Potentials of Intelligent Swarms for magnetospheric studies

Earth's magnetosphere is vital for today's technologically dependent society. The energy transferred from the solar wind to the magnetosphere triggers electromagnetic storms on Earth, knocking out power grids and infrastructure | e.g., communication and navigation systems. Despite occurring on our astrophysical doorstep, numerous physical processes connecting the solar wind and our magnetosphere remain poorly understood. To date, over a dozen science missions have own to study the magnetosphere, and many more design studies have been conducted. However, the majority of these solutions relied on large monolithic satellites, which limited the spatial resolution of these investigations, in addition to the technological limitations of the past. To counter these limitations, we propose the use of a satellite swarm, carrying numerous payloads for magnetospheric measurements. Our mission is named APIS | Applications and Potentials of Intelligent Swarms. The APIS mission aims to characterize fundamental plasma processes in the magnetosphere and measure the e ect of the solar wind on our magnetosphere. We propose a swarm of 40 CubeSats in two highly- elliptical orbits around the Earth, which perform radio tomography in the magnetotail at 8{12 Earth Radii (RE) downstream, and the subsolar magnetosphere at 8{12 RE upstream. These maps will be made at both low-resolutions (at 0.5 RE, 5 seconds cadence) and high-resolutions (at 0.025 RE, 2 seconds cadence). In addition, in-situ measurements of the magnetic and electric elds, and plasma density will be performed by on-board instruments. In this publication, we present a design study of the APIS mission, which includes the mission design, navigation, communication, processing, power systems, propulsion and other critical satellite subsystems. The science requirements of the APIS mission levy stringent system requirements, which are addressed using Commercial O -the-Shelf (COTS) technologies. We show the feasibility of the APIS mission using COTS technologies using preliminary link, power, and mass bud- gets. In addition to the technological study, we also investigated the legal considerations of the APIS mission. The APIS mission design study was part of the International Space University Space Studies Program in 2019 (ISU-SSP19) Next Generation Space Systems: Swarms Team Project. The authors o

Microvascular Composite Radiators for Small Spacecraft Thermal Management Systems

Small spacecraft have typically relied on thermal control systems in which waste heat is simply conducted though structural elements to the surface where it is radiated away. This simplistic approach is adequate for low-complexity missions to LEO, but increasingly complex mission profiles are being proposed including missions to deep space locations which present a harsher thermal environment as well as incorporating advanced capabilities which have challenging thermal control requirements such as cryogenically cooled sensors or propulsion systems. The University of Illinois at Urbana-Champaign, in partnership with NASA Ames Research Center, is developing a thermal control system for small spacecraft utilizing a deployable radiator made of a micro-vascular composite material, through which a coolant can be circulated. These microvascular composite radiators contain tiny channels, as small as 100 micrometer diameter, which can only be manufactured using a novel fabrication technique developed at the University of Illinois, the Vaporization of Sacrificial Components (VaSC). Early mission concepts were evaluated to determine the design guidelines for the cooling system definition. Moving forward, thermal vacuum testing of the prototype will raise the TRL to 6 by the end of the two year development program

APIS: Applications and Potentials of Intelligent Swarms for magnetospheric studies

Earth's magnetosphere is vital for today's technologically dependent society. The energy transferred from the solar wind to the magnetosphere triggers electromagnetic storms on Earth, knocking out power grids and infrastructure - e.g., communication and navigation systems. Despite occurring on our astrophysical doorstep, numerous physical processes connecting the solar wind and our magnetosphere remain poorly understood. To date, over a dozen science missions have flown to study the magnetosphere, and many more design studies have been conducted. However, the majority of these solutions relied on large monolithic satellites, which limited the spatial resolution of these investigations, in addition to the technological limitations of the past. To counter these limitations, we propose the use of a satellite swarm, carrying numerous payloads for magnetospheric measurements. Our mission is named APIS - Applications and Potentials of Intelligent Swarms. The APIS mission aims to characterize fundamental plasma processes in the magnetosphere and measure the effect of the solar wind on our magnetosphere. We propose a swarm of 40 CubeSats in two highly-elliptical orbits around the Earth, which perform radio tomography in the magnetotail at 8-12 Earth Radii (R E) downstream, and the subsolar magnetosphere at 8-12 R E upstream. These maps will be made at both low-resolutions (at 0.5 R E, 5 seconds cadence) and high-resolutions (at 0.025 R E, 2 seconds cadence). In addition, in-situ measurements of the magnetic and electric fields, and plasma density will be performed by on-board instruments. In this publication, we present a design study of the APIS mission, which includes the mission design, navigation, communication, processing, power systems, propulsion and other critical satellite subsystems. The science requirements of the APIS mission levy stringent system requirements, which are addressed using Commercial Off-the-Shelf (COTS) technologies. We show the feasibility of the APIS mission using COTS technologies using preliminary link, power, and mass budgets. In addition to the technological study, we also investigated the legal considerations of the APIS mission. The APIS mission design study was part of the International Space University Space Studies Program in 2019 (ISU-SSP19) Next Generation Space Systems: Swarms Team Project. The authors of this publication are the participants of this 9-week project, in addition to the Chairs and Support staff. Electronic

Unraveling biophysical interactions of radiation pneumonitis in non-small-cell lung cancer via Bayesian network analysis

In non-small-cell lung cancer radiotherapy, radiation pneumonitis≥grade 2 (RP2) depends on patients’ dosimetric, clinical, biological and genomic characteristics. We developed a Bayesian network (BN) approach to explore its potential for interpreting biophysical signaling pathways influencing RP2 from a heterogeneous dataset including single nucleotide polymorphisms, micro RNAs, cytokines, clinical data, and radiation treatment plans before and during the course of radiotherapy. Model building utilized 79 patients (21 with RP2) with complete data, and model testing used 50 additional patients with incomplete data. A developed large-scale Markov blanket approach selected relevant predictors. Resampling by k-fold cross-validation determined the optimal BN structure. Area under the receiver-operating characteristics curve (AUC) measured performance. Pre- and during-treatment BNs identified biophysical signaling pathways from the patients’ relevant variables to RP2 risk. Internal cross-validation for the pre-BN yielded an AUC=0.82 which improved to 0.87 by incorporating during treatment changes. In the testing dataset, the pre- and during AUCs were 0.78 and 0.82, respectively. Our developed BN approach successfully handled a high number of heterogeneous variables in a small dataset, demonstrating potential for unraveling relevant biophysical features that could enhance prediction of RP2, although the current observations would require further independent validation

Priority-driven plan optimization in locally advanced lung patients based on perfusion SPECT imaging

Purpose: Limits on mean lung dose (MLD) allow for individualization of radiation doses at safe levels for patients with lung tumors. However, MLD does not account for individual differences in the extent or spatial distribution of pulmonary dysfunction among patients, which leads to toxicity variability at the same MLD. We investigated dose rearrangement to minimize the radiation dose to the functional lung as assessed by perfusion single photon emission computed tomography (SPECT) and maximize the target coverage to maintain conventional normal tissue limits. Methods and materials: Retrospective plans were optimized for 15 patients with locally advanced non-small cell lung cancer who were enrolled in a prospective imaging trial. A staged, priority-based optimization system was used. The baseline priorities were to meet physical MLD and other dose constraints for organs at risk, and to maximize the target generalized equivalent uniform dose (gEUD). To determine the benefit of dose rearrangement with perfusion SPECT, plans were reoptimized to minimize the generalized equivalent uniform functional dose (gEUfD) to the lung as the subsequent priority. Results: When only physical MLD is minimized, lung gEUfD was 12.6 ± 4.9 Gy (6.3-21.7 Gy). When the dose is rearranged to minimize gEUfD directly in the optimization objective function, 10 of 15 cases showed a decrease in lung gEUfD of >20% (lung gEUfD mean 9.9 ± 4.3 Gy, range 2.1-16.2 Gy) while maintaining equivalent planning target volume coverage. Although all dose-limiting constraints remained unviolated, the dose rearrangement resulted in slight gEUD increases to the cord (5.4 ± 3.9 Gy), esophagus (3.0 ± 3.7 Gy), and heart (2.3 ± 2.6 Gy). Conclusions: Priority-driven optimization in conjunction with perfusion SPECT permits image guided spatial dose redistribution within the lung and allows for a reduced dose to the functional lung without compromising target coverage or exceeding conventional limits for organs at risk

Applications and Potentials of Intelligent Swarms for magnetospheric studies

Earth's magnetosphere is vital for today's technologically dependent society. To date, numerous design studies have been conducted and over a dozen science missions have flown to study the magnetosphere. However, a majority of these solutions relied on large monolithic satellites, which limited the spatial resolution of these investigations, as did the technological limitations of the past. To counter these limitations, we propose the use of a satellite swarm carrying numerous and distributed payloads for magnetospheric measurements. Our mission is named APIS — Applications and Potentials of Intelligent Swarms. The APIS mission aims to characterize fundamental plasma processes in the Earth's magnetosphere and measure the effect of the solar wind on our magnetosphere. We propose a swarm of 40 CubeSats in two highly-elliptical orbits around the Earth, which perform radio tomography in the magnetotail at 8–12 Earth Radii (RE) downstream, and the subsolar magnetosphere at 8–12 RE upstream. These maps will be made at both low-resolutions (at 0.5 RE, 5 s cadence) and high-resolutions (at 0.025 RE, 2 s cadence). In addition, in-situ measurements of the magnetic and electric fields, plasma density will be performed by on-board instruments. In this article, we present an outline of previous missions and designs for magnetospheric studies, along with the science drivers and motivation for the APIS mission. Furthermore, preliminary design results are included to show the feasibility of such a mission. The science requirements drive the APIS mission design, the mission operation and the system requirements. In addition to the various science payloads, critical subsystems of the satellites are investigated e.g., navigation, communication, processing and power systems. Our preliminary investigation on the mass, power and link budgets indicate that the mission could be realized using Commercial Off-the-Shelf (COTS) technologies and with homogeneous CubeSats, each with a 12U form factor. We summarize our findings, along with the potential next steps to strengthen our design study.</p

APIS : Applications and potentials of intelligent swarms for magnetospheric studies

Earth's magnetosphere is vital for today's technologically dependent society. The energy transferred from the solar wind to the magnetosphere triggers electromagnetic storms on Earth, knocking out power grids and infrastructure - e.g., communication and navigation systems. Despite occurring on our astrophysical doorstep, numerous physical processes connecting the solar wind and our magnetosphere remain poorly understood. To date, over a dozen science missions have flown to study the magnetosphere, and many more design studies have been conducted. However, the majority of these solutions relied on large monolithic satellites, which limited the spatial resolution of these investigations, in addition to the technological limitations of the past. To counter these limitations, we propose the use of a satellite swarm, carrying numerous payloads for magnetospheric measurements. Our mission is named APIS - Applications and Potentials of Intelligent Swarms. The APIS mission aims to characterize fundamental plasma processes in the magnetosphere and measure the effect of the solar wind on our magnetosphere. We propose a swarm of 40 CubeSats in two highly-elliptical orbits around the Earth, which perform radio tomography in the magnetotail at 8-12 Earth Radii (RE) downstream, and the subsolar magnetosphere at 8-12 RE upstream. These maps will be made at both low-resolutions (at 0.5 RE, 5 seconds cadence) and high-resolutions (at 0.025 RE, 2 seconds cadence). In addition, in-situ measurements of the magnetic and electric fields, and plasma density will be performed by on-board instruments. In this publication, we present a design study of the APIS mission, which includes the mission design, navigation, communication, processing, power systems, propulsion and other critical satellite subsystems. The science requirements of the APIS mission levy stringent system requirements, which are addressed using Commercial Off-the-Shelf (COTS) technologies. We show the feasibility of the APIS mission using COTS technologies using preliminary link, power, and mass budgets. In addition to the technological study, we also investigated the legal considerations of the APIS mission. The APIS mission design study was part of the International Space University Space Studies Program in 2019 (ISU-SSP19) Next Generation Space Systems: Swarms Team Project. The authors of this publication are the participants of this 9-week project, in addition to the Chairs and Support staff.</p