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Estimating Calibrated Risks Using Focal Loss and Gradient-Boosted Trees for Clinical Risk Prediction
No full textProbability calibration and decision threshold selection are fundamental aspects of risk prediction and classification, respectively. A strictly proper loss function is used in clinical risk prediction applications to encourage a model to predict calibrated class-posterior probabilities or risks. Recent studies have shown that training with focal loss can improve the discriminatory power of gradient-boosted decision trees (GBDT) for classification tasks with an imbalanced or skewed class distribution. However, the focal loss function is not a strictly proper loss function. Therefore, the output of GBDT trained using focal loss is not an accurate estimate of the true class-posterior probability. This study aims to address the issue of poor calibration of GBDT trained using focal loss in the context of clinical risk prediction applications. The methodology utilizes a closed-form transformation of the confidence scores of GBDT trained with focal loss to estimate calibrated risks. The closed-form transformation relates the focal loss minimizer and the true-class posterior probability. Algorithms based on Bayesian hyperparameter optimization are provided to choose the focal loss parameter that optimizes discriminatory power and calibration, as measured by the Brier score metric. We assess how the calibration of the confidence scores affects the selection of a decision threshold to optimize the balanced accuracy, defined as the arithmetic mean of sensitivity and specificity. The effectiveness of the proposed strategy was evaluated using lung transplant data extracted from the Scientific Registry of Transplant Recipients (SRTR) for predicting post-transplant cancer. The proposed strategy was also evaluated using data from the Behavioral Risk Factor Surveillance System (BRFSS) for predicting diabetes status. Probability calibration plots, calibration slope and intercept, and the Brier score show that the approach improves calibration while maintaining the same discriminatory power according to the area under the receiver operating characteristics curve (AUROC) and the H-measure. The calibrated focal-aware XGBoost achieved an AUROC, Brier score, and calibration slope of 0.700, 0.128, and 0.968 for predicting the 10-year cancer risk, respectively. The miscalibrated focal-aware XGBoost achieved equal AUROC but a worse Brier score and calibration slope (0.140 and 1.579). The proposed method compared favorably to the standard XGBoost trained using cross-entropy loss (AUROC of 0.755 versus 0.736 in predicting the 1-year risk of cancer). Comparable performance was observed with other risk prediction models in the diabetes prediction task
Development of a Lightweight VOC Oxidation Catalyst for Spacecraft Trace Contaminant Control
No full textKevin Lee, Collins Aerospace (An RTX Business), United StatesICES302: Physico-Chemical Life Support- Air Revitalization
Systems -Technology and Process DevelopmentThe 54th International Conference on Environmental Systems was held in Prague, Czechia, on 13 July 2025 through 17 July 2025.Collins Aerospace has developed a novel lightweight
volatile organic compounds (VOC) oxidation catalyst that
addresses critical challenges in spacecraft trace
contaminant control systems. This innovative catalyst
demonstrates comparable catalytic performance over the
current flight catalyst used in the Atmospheric
Revitalization System (ARS), in addition to reduced mass,
volume, and cost, while maintaining high VOC conversion
efficiency. In addition to VOC conversion, the catalyst
shows strong potential for ozone (O3) degradation and
carbon monoxide (CO) oxidation, making it highly versatile
for both environmental control and life support systems
(ECLSS) aboard spacecraft applications. Efforts are ongoing
to adapt the catalyst to monolith structures to enable
higher space velocities and reduce pressure drop without
sacrificing performance. A key focus is on the development
of an optimized coating technique to ensure uniform
catalytic activity across the substrate, which is critical
for maximizing efficiency and reliability in operational
environments. The findings presented will provide a new and
original contribution to the state of the art in
environmental systems, showcasing advancements in catalyst
technology that can improve the sustainability and
effectiveness of life support systems
Interior Planning for The Habitation Module to be Installed Inside the Lunar Pit
No full textMasato Ohata, Takenaka Corporation, JapanJun Sato, The University of Tokyo, JapanSho Tanaka, Takenaka Corporation, JapanTatsuho Sato, Takenaka Corporation, JapanRyuya Matsuoka, Takenaka Corporation, JapanHideaki Tani, Takenaka Corporation, JapanSaneyuki Kawabata, The University of Tokyo, JapanTomohiro Yokozeki, The University of Tokyo, JapanKazuya Saito, Kyushu University, JapanNao Hoshinouchi, Osaka University, JapanMasato Sakurai, Japan Aerospace Exploration Agency (JAXA), JapanYasuhiro Awata, Japan Aerospace Exploration Agency (JAXA), JapanICES502: Space ArchitectureThe 54th International Conference on Environmental Systems was held in Prague, Czechia, on 13 July 2025 through 17 July 2025.Currently, numerous vertical holes leading to underground
cavities have been discovered on the lunar surface. These
vertical holes or underground cavities, such as lava tubes,
are likely less affected by radiation exposure and
meteorite impacts compared to the lunar surface. They also
potentially have less temperature fluctuation, making them
considered advantageous conditions for future lunar
habitation bases.
The authors have previously proposed a "minimal" structure
as a "base camp" to serve as an initial outpost when humans
begin to stay on the Moon. This base camp is designed to
support both "manned exploration" and "unmanned
construction" while also serving as a stepping stone
towards "lunar habitation." This paper reports on the
internal architectural planning and facility planning for
the "habitation module" at this base camp.
The "habitation module" proposed in this development is
designed for four people staying six months, with the
expanded main body size being 11m wide × 18m long. The
module body is made of 2mm thick aluminum in a pillow-like
shape and is an inflatable type, expanding with internal
air pressure. The room floor is set 200mm below the
module's center height. Here, life support systems, thermal
circulation equipment, communication devices, and various
living supplies are arranged, along with a laboratory and
daily living areas. At the rear hatch end, there are four
independent sleeping spaces.
The area under the floor is mainly used as a plant
cultivation area, with planting tank units, air
conditioning units, and wastewater tanks. In this study,
the shapes of each equipment were simplified, and a model
was created to confirm whether the necessary functional
equipment could fit within the limited volume without
compromising inhabitant living conditions. Additionally,
the paper also outlines the plan for the "plant cultivation
area" located under the floor
Integrated Metrics Driven Human-in-the-Loop Simulation for the Development of Human Machine Teams in Advanced Environmental System Applications
No full textTristan Endsley, Draper, United StatesSherrie Holder, Draper, United StatesKenneth Stroud, Draper, United StatesICES405: Human/Robotics/Artificial Intelligence System
IntegrationThe 54th International Conference on Environmental Systems was held in Prague, Czechia, on 13 July 2025 through 17 July 2025.Long duration space flight missions will require higher
levels of mission reliance on autonomous and artificial
intelligent systems to enable successful outcomes. Missions
to the moon and Mars will require advancement in
intelligent systems support to manage and facilitate
mission outcomes, and crew autonomy and survival. However,
critical environmental and life support systems may
leverage these technologies in many ways in order to
facilitate higher levels of crew autonomy onboard.
Technology with greater autonomy capabilities does not
necessarily lead to better mission outcomes. Instead, the
ability to have humans and intelligent machine systems
(autonomous, artificial intelligence (AI), and robotic
systems) working collaboratively, and even as part of a
team will be a critical enabler for supporting complex
mission operations within the space domain. These future
Human Machine teaming technologies and systems will require
significant investment in human centered development to
ensure that any intelligent system incorporated into
mission and life critical systems is effectively
integrated. Human-in-the-loop (HITL), ground-based
simulations for engineering development, verification and
test can be leveraged to support the development and
integration of advanced technical systems such as
autonomy/AI.
In this paper, the authors describe how a HITL simulation
developed to provide integrated metrics and measurement
collection can provide critical design feedback early in
the development process for future intelligent
environmental systems applications such as smart habitats,
as well as autonomous support systems for In-situ Resource
Utilization (ISRU) and orbital operations and spacecraft.
Building upon the human machine teaming taxonomy described
in Endsley and Appleby, 20241 this paper describes how
human readiness levels (HRLs) should be established for
future human machine teams in the space flight environment.
It describes how HITL, ground-based simulations for
engineering development, and test can be used to support
the development and integration of advanced technical
systems such as autonomy/AI in space flight applications
Spacecraft Water Impurity Monitor (SWIM), a System for Water Quality Analysis on Exploration Missions Beyond LEO
No full textEvan Neidholdt, KBR, United StatesStuart Pensinger, National Aeronautics and Space Administration (NASA), United StatesMichael Callahan, National Aeronautics and Space Administration (NASA), United StatesEmily Rabel, National Aeronautics and Space Administration (NASA), United StatesAaron Noell, NASA Jet Propulsion Laboratory (JPL), United StatesDragan Nikolic, NASA Jet Propulsion Laboratory (JPL), United StatesCharles Malone, NASA Jet Propulsion Laboratory (JPL), United StatesPeter Willis, NASA Jet Propulsion Laboratory (JPL), United StatesStojan Madzunkov, NASA Jet Propulsion Laboratory (JPL), United StatesICES406: Spacecraft Water/Air Quality: Maintenance and
MonitoringThe 54th International Conference on Environmental Systems was held in Prague, Czechia, on 13 July 2025 through 17 July 2025.Exploration missions beyond low-earth-orbit (LEO) will
require advanced instrumentation to monitor water quality.
Traveling beyond LEO means the transfer of water samples to
an Earth-based laboratory for detailed analysis is not
possible. Detailed analysis of water composition during
exploration is still necessary, because having the
capability to determine the specific organic chemical
causing a change in total organic carbon (TOC) or the
specific metal or ionic species causing a change in
conductivity has the potential to steer the crew health and
system management decisions differently. On a new vehicle
such as a lunar or Mars surface habitat or a Mars transit
vehicle, the occasion of finding “new” impurities not seen
on ISS should be expected. The key is to identify the
impurity so the correct action can be taken. On ISS we can
measure TOC, conductivity, and other physical properties
but do not have the capability for detailed analysis using
vehicle instrumentation. This is acceptable because ISS can
send samples down to Earth for further analysis in a timely
manner. For exploration, the inability to send samples to
Earth is why SWIM is a necessary new technology suite. SWIM
is the answer to detailed water quality analysis when
sample down mass is not available. SWIM is a system
comprising organic and inorganic modules. For organic
chemicals, a gas chromatograph mass spectrometer (GCMS)
detects and identifies organic impurities. For inorganic
species, a capillary electrophoresis capacitively coupled
contactless conductivity detection (CE-C4D) system as well
as ion specific electrodes detect and identify metal ions
and other inorganic salts / acids. The SWIM technology
demonstration project is currently working to define
requirements for an ISS technology demonstration of the
organic and inorganic subsystems, while continuing to
conduct technology feasibility and technology maturation
efforts prior to beginning detailed system design for the
flight instrument
Houston...We Have a Cost Problem: A Financial Analysis of NASA Contractors
No full textKevin Rich, Marquette University, United StatesFinnbar Cocoman, Marquette University, United StatesKate Dugan, Marquette University, United StatesAndrea Golvach, Marquette University, United StatesTyler Miller, Marquette University, United StatesHunter Sandidge, Marquette University, United StatesICES501: Life Support Systems Engineering and AnalysisThe 54th International Conference on Environmental Systems was held in Prague, Czechia, on 13 July 2025 through 17 July 2025.A recent Government Accountability Office (GAO) report
highlighted that 15 projects in the development phase of
NASA’s acquisition process were responsible for $12 billion
in cost overruns and cumulative schedule delays of 28
years. One possible culprit involves outside contractors,
given they ultimately receive a significant piece of the
NASA budget. Additionally, recent high-profile endeavors
such as the Artemis program have faced scrutiny over their
procurement strategies causing increases in costs and
scheduling delays. Understanding patterns in historical
data can provide valuable insights into cost management
practices. In this study, we perform a comprehensive
analysis of NASA contractors in terms of who is receiving
contracts, what they are spending on, and how the contracts
are structured. We use prime contractor data from 2008 to
2024 and find evidence that fixed price contracts are
associated with smaller contract values, slower contract
growth, and fewer modifications. We also find that fixed
prices contracts are more likely to be awarded on a
competitive basis, while research contracts are less likely
to be awarded competitively. Furthermore, district-level
representation on the House, Science, Space, and Technology
Committee is associated with competitive contracts,
suggesting that political influence plays a role in the
selection process. Overall, this study underscores the
importance of transparent, data-driven evaluation in
optimizing NASA’s resource allocation and enhancing mission
planning strategies
Sleep Problems, Emotion (Dys)regulation, and Positive Affect: The Moderating Role of Physical Activity
No full textSleep problems have been consistently linked to poorer emotional functioning over time among children and adolescents. Conversely, physical activity has been linked to improved emotion regulation and higher levels of positive affect. While children engage in both sleep and physical activity daily, relatively little is known about how these two critical health behaviors interact to influence children’s emotional functioning. The central aim of the current study was to evaluate physical activity as a moderator of the associations between sleep problems and emotional functioning over a 6-month period during middle childhood. Participants included 284 children (49.5% girls, 52.8% Hispanic/Latinx, ages 7-12) in third through fifth grade and their homeroom teachers. Sleep problems and physical activity were assessed at baseline using child-reports. Emotion (dys)regulation was assessed at baseline and again approximately 6 months later using child- and teacher-reports. Child-reports of positive affect were also assessed at baseline and 6 months later. A series of multilevel models were estimated. Consistent with previous research, sleep problems were linked to poorer emotional functioning. Contrary to hypotheses, however, physical activity was only uniquely associated with positive affect, and it did not significantly moderate the links from sleep problems to emotional functioning. Supplemental analysis did reveal a three-way interaction between sleep disturbance, physical activity, and grade level in the prediction of child-reported emotion regulation, indicating that physical activity may be an important protective factor for older students. These findings suggest that prevention and intervention efforts should properly screen for children experiencing problems with their sleep and promote healthy sleep habits and regular physical activity
SWCPC 438 Negatives #35 Joe B. Matthews, undated.
No full textThe collection features portraits of sixty-one prominent cattle ranchers, both male and female, who were considered to be the “Cattle Kings of Texas.