Plasma Science in Planetary Entry

Spacecraft entering a planetary atmosphere dissipate a great deal of energy into the surrounding gas. In the frame of reference of the vehicle, the atmospheric gas suddenly decelerates from hypersonic (Mach ~5-50) to subsonic velocities. The kinetic energy of the gas is rapidly converted to thermal and chemical energy, forming a bow shock behind which a plasma with energies on the order of one electron volt (eV) is produced. The resulting shock layer relaxes from strong thermal non-equilibrium that is translationally hot but internally cold and un-ionized toward a thermochemically equilibrated plasma over a distance of a few centimeters. Composition is dependent upon the planetary atmosphere Air for Earth, CO2/N2 for Mars and Venus, N2/CH4 for Titan and H2/He/CH4 for Saturn, Neptune and Jupiter. Typical velocities of entry may range from 3-7 km/s (4-25 MJ/kg) for Titan/Mars, 8-14 km/s (30-100 MJ/kg) for Earth/Venus, and 25-40 km/s (300-800 MJ/kg) for outer planets. The equilibrium plasmas produced from these conditions are highly dissociated (up to and above 99%) and ionized (0.1- 15%), with temperatures from 7,000-15,000K and pressures from 0.1-1.0 bar. Understanding the behavior of these plasmas the way in which they approach equilibrium, how they radiate, and how they interact with materials is an active area of research necessitated by requirements to predict and test the performance of thermal protection systems (TPS) that enable spacecraft to deliver scientific instruments, and people, to foreign worlds and back to Earth. The endeavor is a multi-physics problem, with key processes highlighted in Fig. 1. This white paper describes the current state of the art in simulating shock layer plasmas both computationally and in ground test facilities. Gaps requiring further research and development are identified

Evaluating the Utility of a Psychoeducational Serious Game (SPARX) in Protecting Inuit Youth From Depression: Pilot Randomized Controlled Trial.

BACKGROUND: Inuit youth in Northern Canada show considerable resilience in the face of extreme adversities. However, they also experience significant mental health needs and some of the highest adolescent suicide rates in the world. Disproportionate rates of truancy, depression, and suicide among Inuit adolescents have captured the attention of all levels of government and the country. Inuit communities have expressed an urgent imperative to create, or adapt, and then evaluate prevention and intervention tools for mental health. These tools should build upon existing strengths, be culturally appropriate for Inuit communities, and be accessible and sustainable in Northern contexts, where mental health resources are often scarce. OBJECTIVE: This pilot study assesses the utility, for Inuit youth in Canada, of a psychoeducational e-intervention designed to teach cognitive behavioral therapy strategies and techniques. This serious game, SPARX, had previously demonstrated effectiveness in addressing depression with Māori youth in New Zealand. METHODS: The Nunavut Territorial Department of Health sponsored this study, and a team of Nunavut-based community mental health staff facilitated youth's participation in an entirely remotely administered pilot trial using a modified randomized control approach with 24 youths aged 13-18 across 11 communities in Nunavut. These youth had been identified by the community facilitators as exhibiting low mood, negative affect, depressive presentations, or significant levels of stress. Entire communities, instead of individual youth, were randomly assigned to an intervention group or a waitlist control group. RESULTS: Mixed models (multilevel regression) revealed that participating youth felt less hopeless (P=.02) and engaged in less self-blame (P=.03), rumination (P=.04), and catastrophizing (P=.03) following the SPARX intervention. However, participants did not show a decrease in depressive symptoms or an increase in formal resilience indicators. CONCLUSIONS: Preliminary results suggest that SPARX may be a good first step for supporting Inuit youth with skill development to regulate their emotions, challenge maladaptive thoughts, and provide behavioral management techniques such as deep breathing. However, it will be imperative to work with youth and communities to design, develop, and test an Inuit version of the SPARX program, tailored to fit the interests of Inuit youth and Elders in Canada and to increase engagement and effectiveness of the program. TRIAL REGISTRATION: ClinicalTrials.gov NCT05702086; https://www.clinicaltrials.gov/ct2/show/NCT05702086.fals

A Nunavut community-directed Inuit youth mental wellness initiative: making I-SPARX fly

Inuit youth in Nunavut (NU) are resilient but face a protracted suicide crisis. The SPARX serious game and e-intervention, developed originally in New Zealand, teaches youth cognitive behavioural therapy (CBT) skills to ameliorate stress and depression. Inuit youth in NU reviewed and culturally adapted SPARX and an existing wellness outcome measure for Inuit. One hundred and twenty-one youth, aged 13 to 24, across NU then tested, played, and evaluated I(nuit)-SPARX, showing improvement in several areas of wellbeing post-play. Youth completed a CBT skills survey, engaged in sharing circles to assess CBT skill retention, and shared their thoughts about the usefulness and cultural fit of I-SPARX with Inuit Qaujimajatuqangit (IQ). Communication Skills, Listening Skills, and Problem Solving emerged as the most helpful learned CBT skills, and NU youth provided real-world examples of using I-SPARX skills to support their mental wellness. Several principles of IQ were exemplified and upheld in the content of the adapted SPARX tool and the process of the project as a whole. Empirically grounded, asynchronous e-tools, developed in collaboration with Inuit communities to ensure cultural specificity, may support psychological wellness in communities where mental health resources are scarce.fals

More than a century of bathymetric observations and present-day shallow sediment characterization in Belfast Bay, Maine, USA: implications for pockmark field longevity

This paper is not subject to U.S. copyright. The definitive version was published in Geo-Marine Letters 31 (2011): 237-248, doi:10.1007/s00367-011-0228-0.Mechanisms and timescales responsible for pockmark formation and maintenance remain uncertain, especially in areas lacking extensive thermogenic fluid deposits (e.g., previously glaciated estuaries). This study characterizes seafloor activity in the Belfast Bay, Maine nearshore pockmark field using (1) three swath bathymetry datasets collected between 1999 and 2008, complemented by analyses of shallow box-core samples for radionuclide activity and undrained shear strength, and (2) historical bathymetric data (report and smooth sheets from 1872, 1947, 1948). In addition, because repeat swath bathymetry surveys are an emerging data source, we present a selected literature review of recent studies using such datasets for seafloor change analysis. This study is the first to apply the method to a pockmark field, and characterizes macro-scale (>5 m) evolution of tens of square kilometers of highly irregular seafloor. Presence/absence analysis yielded no change in pockmark frequency or distribution over a 9-year period (1999–2008). In that time pockmarks did not detectably enlarge, truncate, elongate, or combine. Historical data indicate that pockmark chains already existed in the 19th century. Despite the lack of macroscopic changes in the field, near-bed undrained shear-strength values of less than 7 kPa and scattered downcore 137Cs signatures indicate a highly disturbed setting. Integrating these findings with independent geophysical and geochemical observations made in the pockmark field, it can be concluded that (1) large-scale sediment resuspension and dispersion related to pockmark formation and failure do not occur frequently within this field, and (2) pockmarks can persevere in a dynamic estuarine setting that exhibits minimal modern fluid venting. Although pockmarks are conventionally thought to be long-lived features maintained by a combination of fluid venting and minimal sediment accumulation, this suggests that other mechanisms may be equally active in maintaining such irregular seafloor morphology. One such mechanism could be upwelling within pockmarks induced by near-bed currents.Graduate support for Brothers came from a Maine Economic Improvement Fund Dissertation Fellowship

Individual working memory capacity is uniquely correlated with feature-based attention when combined with spatial attention

A growing literature suggests that working memory and attention are closely related constructs. Both involve the selection of task-relevant information, and both are characterized by capacity limits. Furthermore, studies using a variety of methodological approaches have demonstrated convergent working memory and attention-related processing at the individual, neural and behavioral level. Given the varieties of both constructs, the specific kinds of attention and WM must be considered. We find that individuals’ working memory capacity (WMC) uniquely interacts with feature-based attention when combined with spatial attention in a cuing paradigm (Posner, 1980). Our findings suggest a positive correlation between WM and feature-based attention only within the spotlight of spatial attention. This finding lends support to the controlled attention view of working memory by demonstrating that integrated feature-based expectancies are uniquely correlated with individual performance on a working memory task

Genetic Variation and Climatic Impacts on Survival and Growth of White Spruce in Alberta, Canada

Abstract Because climate has the greatest effect in determining the genetic structure of forest tree species, climatic variables with large effects on growth and survival need to be identified. This would enable proper matching of tree populations to planting sites in the present and future climates. We analysed 24-year survival (S24), height (H24) and diameter (D24) from a series of white spruce provenance trials with 46 populations and 8 test sites in Alberta, Canada. We determined: (1) the amount and pattern of genetic variation, (2) the response of populations to climatic transfer and (3) the potential effects of climate change (2030-2039) on H24 and S24 of the species in Alberta. We found that: (1) using the intraclass correlation, the between-population genetic variance was 10.6% (H24) and 6.6% (D24) of the betweenpopulation phenotypic variance across sites, (2) three climatic white spruce regions exist in Alberta within which variation in growth potential is strongly clinal, (3) the annual moisture index (AMI) expressed as a ratio of degree days above 5°C (GDD) and mean annual precipitation (MAP) was the major determinant of survival and growth at the test sites, (4) we found that at the level of AMI predicted for the 2030-2039 period, survival and growth would decline substantially in the continental part (northern and central) of Alberta where drought already exists. However, during the same period, survival and growth would increase substantially in the foothills and Rocky Mountains region where growth is currently limited by low GDD due to a short growing season.</jats:p