354 research outputs found
Artemis Curation: Preparing for Sample Return from the Lunar South Pole
Space Policy Directive-1 mandates that the United States will lead the return of humans to the Moon for long-term exploration and utilization, followed by human missions to Mars and other destinations. In addition, the Vice President stated that It is the stated policy of this administration and the United States of America to return American astronauts to the Moon within the next five years, that is, by 2024. These efforts, under the umbrella of the recently formed Artemis Program, include such historic goals as the flight of the first woman to the Moon and the exploration of the lunar south-polar region. Among the top priorities of the Artemis Program is the return of a suite of geologic samples, providing new and significant opportunities for progressing lunar science and human exploration. In particular, successful sample return is necessary for understanding the history of volatiles in the Solar System and the evolution of the Earth-Moon system, fully constraining the hazards of the lunar polar environment for astronauts, and providing the necessary data for constraining the abundance and distribution of resources for in-situ resource utilization (ISRU). Here we summarize the ef-forts of the Astromaterials Acquisition and Curation Office (hereafter referred to as the Curation Office) to ensure the success of Artemis sample return (per NASA Policy Directive (NPD) 7100.10E)
Asymptotic description of solutions of the exterior Navier Stokes problem in a half space
We consider the problem of a body moving within an incompressible fluid at
constant speed parallel to a wall, in an otherwise unbounded domain. This
situation is modeled by the incompressible Navier-Stokes equations in an
exterior domain in a half space, with appropriate boundary conditions on the
wall, the body, and at infinity. We focus on the case where the size of the
body is small. We prove in a very general setup that the solution of this
problem is unique and we compute a sharp decay rate of the solution far from
the moving body and the wall
Does the timing and duration of mental health problems during childhood and adolescence matter for labour market participation of young adults?
BACKGROUND: Little is known about the timing and duration of mental health problems (MHPs) on young adults’ labour market participation (LMP). This life-course study aims to examine whether and how the timing and duration of MHPs between childhood and young adulthood are associated with LMP in young adulthood. METHODS: Logistic regression analyses were performed with data from the Tracking Adolescents’ Individual Lives Survey (TRAILS), a Dutch prospective cohort study with 15-year follow-up (N=874). Internalising and externalising problems were measured by the Youth/Adult Self-Report at ages 11, 13, 16, 19 and 22. Labour market participation (having a paid job yes/no) was assessed at age 26. RESULTS: Internalising problems at all ages and externalising problems at age 13, 19 and 22 were associated with an increased risk of not having a paid job (internalising problems ORs ranging from 2.24, 95% CI 1.02 to 4.90 at age 11 to OR 6.58, CI 3.14 to 13.80 at age 22; externalising problems ORs from 2.84, CI 1.11 to 7.27 at age 13 to OR 6.36, CI 2.30 to 17.56 at age 22). Especially a long duration of internalising problems increased the risk of not having a paid job in young adulthood. CONCLUSION: The duration of MHPs during childhood and adolescence is strongly associated with not having paid work in young adulthood. This emphasises the necessity of applying a life-course perspective when investigating the effect of MHPs on LMP. Early monitoring, mental healthcare and the (early) provision of employment support may improve young adult’s participation in the labour market
On the existence of monotonic fronts for a class of physical problems described by the equation
We obtain an upper bound on the value of for which monotonic front
solutions of the equation with may
exist.Comment: Latex manuscript, 10 pages, 2 figures available on request from
[email protected]
Particle trajectories in linearized irrotational shallow water flows
We investigate the particle trajectories in an irrotational shallow water
flow over a flat bed as periodic waves propagate on the water's free surface.
Within the linear water wave theory, we show that there are no closed orbits
for the water particles beneath the irrotational shallow water waves. Depending
on the strength of underlying uniform current, we obtain that some particle
trajectories are undulating path to the right or to the left, some are looping
curves with a drift to the right and others are parabolic curves or curves
which have only one loop
A dimension-breaking phenomenon for water waves with weak surface tension
It is well known that the water-wave problem with weak surface tension has
small-amplitude line solitary-wave solutions which to leading order are
described by the nonlinear Schr\"odinger equation. The present paper contains
an existence theory for three-dimensional periodically modulated solitary-wave
solutions which have a solitary-wave profile in the direction of propagation
and are periodic in the transverse direction; they emanate from the line
solitary waves in a dimension-breaking bifurcation. In addition, it is shown
that the line solitary waves are linearly unstable to long-wavelength
transverse perturbations. The key to these results is a formulation of the
water wave problem as an evolutionary system in which the transverse horizontal
variable plays the role of time, a careful study of the purely imaginary
spectrum of the operator obtained by linearising the evolutionary system at a
line solitary wave, and an application of an infinite-dimensional version of
the classical Lyapunov centre theorem.Comment: The final publication is available at Springer via
http://dx.doi.org/10.1007/s00205-015-0941-
A rigorous implementation of the Jeans--Landau--Teller approximation
Rigorous bounds on the rate of energy exchanges between vibrational and
translational degrees of freedom are established in simple classical models of
diatomic molecules. The results are in agreement with an elementary
approximation introduced by Landau and Teller. The method is perturbative
theory ``beyond all orders'', with diagrammatic techniques (tree expansions) to
organize and manipulate terms, and look for compensations, like in recent
studies on KAM theorem homoclinic splitting.Comment: 23 pages, postscrip
Relationships Between Gratitude and Mental Health Difficulties During the COVID-19 Pandemic in a Southern Region of the United States
Introduction: The extensive disruptions of the COVID-19 pandemic have led to heightened concerns about mental health sequelae. There has been significant interest in identifying factors associated with psychosocial vulnerability or resilience.
Aims: This study examined associations of trait gratitude with mental health difficulties among community residents in a southern state of the US.
Methods: In this cross-sectional online investigation, 543 adults were assessed during an earlier phase of the pandemic, characterized by the reopening of facilities but mounting infection rates. Participants were evaluated using a validated measure of trait gratitude and clinically relevant screening assess-ments of depression, anxiety, and trauma symptoms.
Results: After adjusting for a range of pandemic-associated burdens and sociodemographic factors, multivariable analyses indicated that gratitude was significantly related to diminished levels of depres-sion, anxiety, and trauma. These effects remained significant after additional adjustment for other psychosocial resources (religiousness and perceived support).
Conclusions: Findings provide novel information regarding relationships between gratitude and reduced mental health difficulties among community residents during a stressful period early in the pandemic. Results set the stage for longitudinal research. A disposition to identify and appreciate beneficial experiences might contribute to more favorable adaptation to communal crises, and warrants further investigation
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