1,598 research outputs found
An Architecture to Enable Autonomous Control of Spacecraft
Autonomy is required for manned spacecraft missions distant enough that light-time communication delays make ground-based mission control infeasible. Presently, ground controllers develop a complete schedule of power modes for all spacecraft components based on a large number of factors. The proposed architecture is an early attempt to formalize and automate this process using on-vehicle computation resources. In order to demonstrate this architecture, an autonomous electrical power system controller and vehicle Mission Manager are constructed. These two components are designed to work together in order to plan upcoming load use as well as respond to unanticipated deviations from the plan. The communication protocol was developed using "paper" simulations prior to formally encoding the messages and developing software to implement the required functionality. These software routines exchange data via TCP/IP sockets with the Mission Manager operating at NASA Ames Research Center and the autonomous power controller running at NASA Glenn Research Center. The interconnected systems are tested and shown to be effective at planning the operation of a simulated quasi-steady state spacecraft power system and responding to unexpected disturbances
Illness Labels and Social Distance
The authors examine a key proposition in the modified labeling theoryâthat a psychiatric label increases vulnerability to negative evaluation and social rejectionâusing an experimental design wherein female participants interact with a female teammate over a computer. The authors also evaluate a hypothesis derived from the disease-avoidance account of disgust by examining this same process for a nonpsychiatric illness: food poisoning. In addition, they introduce a composite measure of social distance behavior that is easy to implement in a laboratory experiment. The authors find, as predicted, that women seek greater social distance from teammates with a history of psychiatric or food poisoning hospitalization than they do from teammates with no hospitalization history. But, contrary to predictions, a teammateâs hospitalization history does not affect participantsâ ratings of her likability. The results also do not vary significantly by psychiatric diagnosis (depression vs. schizophrenia), suggesting that the stigma of depression may be just as strong as the stigma of schizophrenia when information about symptoms is not available. The authors discuss the implications of these findings for the modified labeling theory of mental illness and for the literature on disgust and stigma. They also outline avenues for future research.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline
An exploratory analysis of the impact of family functioning on treatment for depression in adolescents.
This article explores aspects of family environment and parent-child conflict that may predict or moderate response to acute treatments among depressed adolescents (N = 439) randomly assigned to fluoxetine, cognitive behavioral therapy, their combination, or placebo. Outcomes were Week 12 scores on measures of depression and global impairment. Of 20 candidate variables, one predictor emerged: Across treatments, adolescents with mothers who reported less parent-child conflict were more likely to benefit than their counterparts. When family functioning moderated outcome, adolescents who endorsed more negative environments were more likely to benefit from fluoxetine. Similarly, when moderating effects were seen on cognitive behavioral therapy conditions, they were in the direction of being less effective among teens reporting poorer family environments
Revisiting spin ice physics in the ferromagnetic Ising pyrochlore PrSnO
Pyrochlore materials are characterized by their hallmark network of
corner-sharing rare-earth tetrahedra, which can produce a wide array of complex
magnetic ground states. Ferromagnetic Ising pyrochlores often obey the
"two-in-two-out" spin ice rules, which can lead to a highly-degenerate spin
structure. Large moment systems, such as HoTiO and
DyTiO, tend to host a classical spin ice state with low-temperature
spin freezing and emergent magnetic monopoles. Systems with smaller effective
moments, such as Pr-based pyrochlores, have been proposed as excellent
candidates for hosting a "quantum spin ice" characterized by entanglement and a
slew of exotic quasiparticle excitations. However, experimental evidence for a
quantum spin ice state has remained elusive. Here, we show that the
low-temperature magnetic properties of PrSnO satisfy several
important criteria for continued consideration as a quantum spin ice. We find
that PrSnO exhibits a partially spin-frozen ground state with a
large volume fraction of dynamic magnetism. Our comprehensive bulk
characterization and neutron scattering measurements enable us to map out the
magnetic field-temperature phase diagram, producing results consistent with
expectations for a ferromagnetic Ising pyrochlore. We identify key hallmarks of
spin ice physics, and show that the application of small magnetic fields
(0.75T) suppresses the spin ice state and induces a long-range
ordered magnetic structure. Together, our work clarifies the current state of
PrSnO and encourages future studies aimed at exploring the
potential for a quantum spin ice ground state in this system
LSST Science Book, Version 2.0
A survey that can cover the sky in optical bands over wide fields to faint
magnitudes with a fast cadence will enable many of the exciting science
opportunities of the next decade. The Large Synoptic Survey Telescope (LSST)
will have an effective aperture of 6.7 meters and an imaging camera with field
of view of 9.6 deg^2, and will be devoted to a ten-year imaging survey over
20,000 deg^2 south of +15 deg. Each pointing will be imaged 2000 times with
fifteen second exposures in six broad bands from 0.35 to 1.1 microns, to a
total point-source depth of r~27.5. The LSST Science Book describes the basic
parameters of the LSST hardware, software, and observing plans. The book
discusses educational and outreach opportunities, then goes on to describe a
broad range of science that LSST will revolutionize: mapping the inner and
outer Solar System, stellar populations in the Milky Way and nearby galaxies,
the structure of the Milky Way disk and halo and other objects in the Local
Volume, transient and variable objects both at low and high redshift, and the
properties of normal and active galaxies at low and high redshift. It then
turns to far-field cosmological topics, exploring properties of supernovae to
z~1, strong and weak lensing, the large-scale distribution of galaxies and
baryon oscillations, and how these different probes may be combined to
constrain cosmological models and the physics of dark energy.Comment: 596 pages. Also available at full resolution at
http://www.lsst.org/lsst/sciboo
LSST: from Science Drivers to Reference Design and Anticipated Data Products
(Abridged) We describe here the most ambitious survey currently planned in
the optical, the Large Synoptic Survey Telescope (LSST). A vast array of
science will be enabled by a single wide-deep-fast sky survey, and LSST will
have unique survey capability in the faint time domain. The LSST design is
driven by four main science themes: probing dark energy and dark matter, taking
an inventory of the Solar System, exploring the transient optical sky, and
mapping the Milky Way. LSST will be a wide-field ground-based system sited at
Cerro Pach\'{o}n in northern Chile. The telescope will have an 8.4 m (6.5 m
effective) primary mirror, a 9.6 deg field of view, and a 3.2 Gigapixel
camera. The standard observing sequence will consist of pairs of 15-second
exposures in a given field, with two such visits in each pointing in a given
night. With these repeats, the LSST system is capable of imaging about 10,000
square degrees of sky in a single filter in three nights. The typical 5
point-source depth in a single visit in will be (AB). The
project is in the construction phase and will begin regular survey operations
by 2022. The survey area will be contained within 30,000 deg with
, and will be imaged multiple times in six bands, ,
covering the wavelength range 320--1050 nm. About 90\% of the observing time
will be devoted to a deep-wide-fast survey mode which will uniformly observe a
18,000 deg region about 800 times (summed over all six bands) during the
anticipated 10 years of operations, and yield a coadded map to . The
remaining 10\% of the observing time will be allocated to projects such as a
Very Deep and Fast time domain survey. The goal is to make LSST data products,
including a relational database of about 32 trillion observations of 40 billion
objects, available to the public and scientists around the world.Comment: 57 pages, 32 color figures, version with high-resolution figures
available from https://www.lsst.org/overvie
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