Searches for solar-influenced radioactive decay anomalies using Spacecraft RTGs

Experiments showing a seasonal variation of the nuclear decay rates of a number of different nuclei, and decay anomalies apparently related to solar flares and solar rotation, have suggested that the Sun may somehow be influencing nuclear decay processes. Recently, Cooper searched for such an effect in $^{238}$Pu nuclei contained in the radioisotope thermoelectric generators (RTGs) on board the Cassini spacecraft. In this paper we modify and extend Cooper's analysis to obtain constraints on anomalous decays of $^{238}$Pu over a wider range of models, but these limits cannot be applied to other nuclei if the anomaly is composition-dependent. We also show that it may require very high sensitivity for terrestrial experiments to discriminate among some models if such a decay anomaly exists, motivating the consideration of future spacecraft experiments which would require less precision.Comment: 8 pages, 4 figures (to appear in Astroparticle Physics

TIA1 Mutations in Amyotrophic Lateral Sclerosis and Frontotemporal Dementia Promote Phase Separation and Alter Stress Granule Dynamics.

Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are age-related neurodegenerative disorders with shared genetic etiologies and overlapping clinical and pathological features. Here we studied a novel ALS/FTD family and identified the P362L mutation in the low-complexity domain (LCD) of T cell-restricted intracellular antigen-1 (TIA1). Subsequent genetic association analyses showed an increased burden of TIA1 LCD mutations in ALS patients compared to controls (p = 8.7 × 1

Experimental demonstration of the relationship between the second- and third-order polarizabilities of conjugated donor-acceptor molecules

The dependence of the second- and third-order polarizabilities ((beta) and (gamma) ) on ground-state polarization was measured for a series of donor-acceptor polyenes using electric field induced second harmonic generation and third harmonic generation, respectively. The changes in ground-state polarization, associated with the donor/acceptor strength or solvent polarity, were probed by x-ray crystallography, 1H-NMR, electronic absorption, and Raman spectroscopies. The observed behavior of (beta) and (gamma) as a function of ground- state polarization agrees well with theoretical predictions. In particular, positive and negative peaks, as well as sign changes, were observed for both (beta) and (gamma) . The dependences for (beta) and (gamma) are consistent with a derivative relationship between them. In addition, the third-order polarizability of a series of molecules possessing zero bond length alternation was found to be negative, in agreement with predictions based on the relationship between the polarizabilities and ground-state geometry

Open-ended VQA benchmarking of Vision-Language models by exploiting Classification datasets and their semantic hierarchy

The evaluation of text-generative vision-language models is a challenging yet crucial endeavor. By addressing the limitations of existing Visual Question Answering (VQA) benchmarks and proposing innovative evaluation methodologies, our research seeks to advance our understanding of these models' capabilities. We propose a novel VQA benchmark based on well-known visual classification datasets which allows a granular evaluation of text-generative vision-language models and their comparison with discriminative vision-language models. To improve the assessment of coarse answers on fine-grained classification tasks, we suggest using the semantic hierarchy of the label space to ask automatically generated follow-up questions about the ground-truth category. Finally, we compare traditional NLP and LLM-based metrics for the problem of evaluating model predictions given ground-truth answers. We perform a human evaluation study upon which we base our decision on the final metric. We apply our benchmark to a suite of vision-language models and show a detailed comparison of their abilities on object, action, and attribute classification. Our contributions aim to lay the foundation for more precise and meaningful assessments, facilitating targeted progress in the exciting field of vision-language modeling.Comment: Accepted as Spotlight Paper for ICLR 2024. The first two authors contributed equally to this wor

International Space Station (ISS) Plasma Contactor Unit (PCU) Utilization Plan Assessment Update

The International Space Station (ISS) vehicle undergoes spacecraft charging as it interacts with Earth's ionosphere and magnetic field. The interaction can result in a large potential difference developing between the ISS metal chassis and the local ionosphere plasma environment. If an astronaut conducting extravehicular activities (EVA) is exposed to the potential difference, then a possible electrical shock hazard arises. The control of this hazard was addressed by a number of documents within the ISS Program (ISSP) including Catastrophic Safety Hazard for Astronauts on EVA (ISS-EVA-312-4A_revE). The safety hazard identified the risk for an astronaut to experience an electrical shock in the event an arc was generated on an extravehicular mobility unit (EMU) surface. A catastrophic safety hazard, by the ISS requirements, necessitates mitigation by a two-fault tolerant system of hazard controls. Traditionally, the plasma contactor units (PCUs) on the ISS have been used to limit the charging and serve as a "ground strap" between the ISS structure and the surrounding ionospheric plasma. In 2009, a previous NASA Engineering and Safety Center (NESC) team evaluated the PCU utilization plan (NESC Request #07-054-E) with the objective to assess whether leaving PCUs off during non-EVA time periods presented risk to the ISS through assembly completion. For this study, in situ measurements of ISS charging, covering the installation of three of the four photovoltaic arrays, and laboratory testing results provided key data to underpin the assessment. The conclusion stated, "there appears to be no significant risk of damage to critical equipment nor excessive ISS thermal coating damage as a result of eliminating PCU operations during non- EVA times." In 2013, the ISSP was presented with recommendations from Boeing Space Environments for the "Conditional" Marginalization of Plasma Hazard. These recommendations include a plan that would keep the PCUs off during EVAs when the space environment forecast input to the ISS charging model indicates floating potentials (FP) within specified limits. These recommendations were based on the persistence of conditions in the space environment due to the current low solar cycle and belief in the accuracy and completeness of the ISS charging model. Subsequently, a Noncompliance Report (NCR), ISS-NCR-232G, Lack of Two-fault Tolerance to EVA Crew Shock in the Low Earth Orbit Plasma Environment, was signed in September 2013 specifying new guidelines for the use of shock hazard controls based on a forecast of the space environment from ISS plasma measurements taken prior to the EVA [ISS-EVA-312-AC, 2012]. This NESC assessment re-evaluates EVA charging hazards through a process that is based on over 14 years of ISS operations, charging measurements, laboratory tests, EMU studies and modifications, and safety reports. The assessment seeks an objective review of the plasma charging hazards associated with EVA operations to determine if any of the present hazard controls can safely change the PCU utilization plan to allow more flexibility in ISS operations during EVA preparation and execution

International Space Station (ISS) Plasma Contactor Unit (PCU) Utilization Plan Assessment Update

The NASA Engineering and Safety Center (NESC) received a request to support the Assessment of the International Space Station (ISS) Plasma Contactor Unit (PCU) Utilization Update. The NESC conducted an earlier assessment of the use of the PCU in 2009. This document contains the outcome of the assessment update

Chronic inhibition, self-control and eating behavior: test of a 'resource depletion' model

The current research tested the hypothesis that individuals engaged in long-term efforts to limit food intake (e.g., individuals with high eating restraint) would have reduced capacity to regulate eating when self-control resources are limited. In the current research, body mass index (BMI) was used as a proxy for eating restraint based on the assumption that individuals with high BMI would have elevated levels of chronic eating restraint. A preliminary study (Study 1) aimed to provide evidence for the assumed relationship between eating restraint and BMI. Participants (N = 72) categorized into high or normal-range BMI groups completed the eating restraint scale. Consistent with the hypothesis, results revealed significantly higher scores on the weight fluctuation and concern for dieting subscales of the restraint scale among participants in the high BMI group compared to the normal-range BMI group. The main study (Study 2) aimed to test the hypothesized interactive effect of BMI and diminished self-control resources on eating behavior. Participants (N = 83) classified as having high or normal-range BMI were randomly allocated to receive a challenging counting task that depleted self-control resources (ego-depletion condition) or a non-depleting control task (no depletion condition). Participants then engaged in a second task in which required tasting and rating tempting cookies and candies. Amount of food consumed during the taste-and-rate task constituted the behavioral dependent measure. Regression analyses revealed a significant interaction effect of these variables on amount of food eaten in the taste-and-rate task. Individuals with high BMI had reduced capacity to regulate eating under conditions of self-control resource depletion as predicted. The interactive effects of BMI and self-control resource depletion on eating behavior were independent of trait self-control. Results extend knowledge of the role of self-control in regulating eating behavior and provide support for a limited-resource model of self-control. © 2013 Hagger et al