4,071 research outputs found
An AI approach for scheduling space-station payloads at Kennedy Space Center
The Payload Processing for Space-Station Operations (PHITS) is a prototype modeling tool capable of addressing many Space Station related concerns. The system's object oriented design approach coupled with a powerful user interface provide the user with capabilities to easily define and model many applications. PHITS differs from many artificial intelligence based systems in that it couples scheduling and goal-directed simulation to ensure that on-orbit requirement dates are satisfied
Analyzing P300 Distractors for Target Reconstruction
P300-based brain-computer interfaces (BCIs) are often trained per-user and
per-application space. Training such models requires ground truth knowledge of
target and non-target stimulus categories during model training, which imparts
bias into the model. Additionally, not all non-targets are created equal; some
may contain visual features that resemble targets or may otherwise be visually
salient. Current research has indicated that non-target distractors may elicit
attenuated P300 responses based on the perceptual similarity of these
distractors to the target category. To minimize this bias, and enable a more
nuanced analysis, we use a generalized BCI approach that is fit to neither user
nor task. We do not seek to improve the overall accuracy of the BCI with our
generalized approach; we instead demonstrate the utility of our approach for
identifying target-related image features. When combined with other intelligent
agents, such as computer vision systems, the performance of the generalized
model equals that of the user-specific models, without any user specific data.Comment: 4 pages, 3 figure
A Six Year Summary of Feedlot Health Records from the Opportunities Farm
Livestock housing at the Opportunities Farm is comprised of three different cattle feeding pen designs. The three pen designs are a monoslope barn (MON), open pens (OPN), and open pens with shelter over the feeding area (OS). Analyses of 6 years of data ranging from 2008 through 2013 were conducted. Morbidity and mortality rates for each year were compared for all cattle fed during the six year interval, regardless of feeding facility design. Cattle fed at the Opportunities Farm during this period had morbidity and mortality rates equivalent to what would be expected by feedlots throughout North America. Morbidity significantly differed by year. Specifically, year influenced incidences of respiratory disease, foot rot, and lameness but had no effect on mortality. A comparative analysis of the effect of feeding pen design on cattle health was conducted. The OPN design had higher total morbidity and incidence of respiratory disease than the OS design. No differences relative to facility design were found for any other animal health measure
Theory of imaging a photonic crystal with transmission near-field optical microscopy
While near-field scanning optical microscopy (NSOM) can provide optical
images with resolution much better than the diffraction limit, analysis and
interpretation of these images is often difficult. We present a theory of
imaging with transmission NSOM that includes the effects of tip field,
tip/sample coupling, light propagation through the sample and light collection.
We apply this theory to analyze experimental NSOM images of a nanochannel glass
(NCG) array obtained in transmission mode. The NCG is a triangular array of
dielectric rods in a dielectric glass matrix with a two-dimensional photonic
band structure. We determine the modes for the NCG photonic crystal and
simulate the observed data. The calculations show large contrast at low
numerical aperture (NA) of the collection optics and detailed structure at high
NA consistent with the observed images. We present calculations as a function
of NA to identify how the NCG photonic modes contribute to and determine the
spatial structure in these images. Calculations are presented as a function of
tip/sample position, sample index contrast and geometry, and aperture size to
identify the factors that determine image formation with transmission NSOM in
this experiment.Comment: 28 pages of ReVTex, 14 ps figures, submitted to Phys. Rev.
Mesoscopic molecular ions in Bose-Einstein condensates
We study the possible formation of large (mesoscopic) molecular ions in an
ultracold degenerate bosonic gas doped with charged particles (ions). We show
that the polarization potentials produced by the ionic impurities are capable
of capturing hundreds of atoms into loosely bound states. We describe the
spontaneous formation of these hollow molecular ions via phonon emission and
suggest an optical technique for coherent stimulated transitions of free atoms
into a specific bound state. These results open up new interesting
possibilities for manipulating tightly confined ensembles.Comment: 4 pages (two-columns), 2 figure
Correlated defects, metal-insulator transition, and magnetic order in ferromagnetic semiconductors
The effect of disorder on transport and magnetization in ferromagnetic III-V
semiconductors, in particular (Ga,Mn)As, is studied theoretically. We show that
Coulomb-induced correlations of the defect positions are crucial for the
transport and magnetic properties of these highly compensated materials. We
employ Monte Carlo simulations to obtain the correlated defect distributions.
Exact diagonalization gives reasonable results for the spectrum of valence-band
holes and the metal-insulator transition only for correlated disorder. Finally,
we show that the mean-field magnetization also depends crucially on defect
correlations.Comment: 4 pages RevTeX4, 5 figures include
Charge Exchange and Chemical Reactions with Trapped Th
We have measured the reaction rates of trapped, buffer gas cooled Th
and various gases and have analyzed the reaction products using trapped ion
mass spectrometry techniques. Ion trap lifetimes are usually limited by
reactions with background molecules, and the high electron affinity of multiply
charged ions such as Th make them more prone to loss. Our results show
that reactions of Th with carbon dioxide, methane, and oxygen all occur
near the classical Langevin rate, while reaction rates with argon, hydrogen,
and nitrogen are orders of magnitude lower. Reactions of Th with oxygen
and methane proceed primarily via charge exchange, while simultaneous charge
exchange and chemical reaction occurs between Th and carbon dioxide.
Loss rates of Th in helium are consistent with reaction with impurities
in the gas. Reaction rates of Th with nitrogen and argon depend on the
internal electronic configuration of the Th.Comment: 9 pages, 10 figures, 4 tables. Submitted to PR
Collaborative Brain-Computer Interface for Human Interest Detection in Complex and Dynamic Settings
Humans can fluidly adapt their interest in complex environments in ways that
machines cannot. Here, we lay the groundwork for a real-world system that
passively monitors and merges neural correlates of visual interest across team
members via Collaborative Brain Computer Interface (cBCI). When group interest
is detected and co-registered in time and space, it can be used to model the
task relevance of items in a dynamic, natural environment. Previous work in
cBCIs focuses on static stimuli, stimulus- or response- locked analyses, and
often within-subject and experiment model training. The contributions of this
work are twofold. First, we test the utility of cBCI on a scenario that more
closely resembles natural conditions, where subjects visually scanned a video
for target items in a virtual environment. Second, we use an
experiment-agnostic deep learning model to account for the real-world use case
where no training set exists that exactly matches the end-users task and
circumstances. With our approach we show improved performance as the number of
subjects in the cBCI ensemble grows, and the potential to reconstruct
ground-truth target occurrence in an otherwise noisy and complex environment.Comment: 6 pages, 6 figure
Aerodynamic Analysis of a Generic Fighter with a Chine Fuselage/Delta Wing Configuration Using Delayed Detached-Eddy Simulation
The Modular Transonic Vortex Investigation (MTVI) program at NASA Langley Research Center investigated the transonic characteristics of generic fighter configurations with chined fuselages and delta wings. Previous experiments show that the fuselage and leading edge vortex interactions are detrimental to the vehicle’s aerodynamic characteristics for angles of attack greater than 23º at low angles of sideslip. This is largely due to abrupt asymmetric vortex breakdown, which leads to pronounced pitch-up and significant nonlinearities in lateral stability that could result in roll departure. An improved understanding of the exact origins of this nonlinear behavior would improve future fighter design, and predictive capabilities of such nonlinearities could drastically reduce the cost associated with flight testing new or modified aircraft. The nonlinearities experienced by the MTVI configuration at 30 degrees angle of attack, Reynolds number of 2.68x106, and Mach number of 0.4 are computed using Delayed Detached-Eddy Simulation. Computational predictions of rolling moment compare very well with previous wind tunnel experiments at the same conditions, including the abrupt, nonlinear increase in rolling moment as a function of sideslip angle at small sideslip angles. A detailed investigation of the CFD data confirms that this nonlinearity is due to a rapid change in the flow field structures from symmetric to asymmetric vortex breakdown
Understanding the role of shame and its consequences in female hypersexual behaviours: A pilot study
Background and aims:
Hypersexuality and sexual addiction among females is a little understudied phenomenon. Shame is thought to be intrinsic to hypersexual behaviours, especially in women. Therefore, the aim of this study was to understand both hypersexual behaviours and consequences of hypersexual behaviours and their respective contributions to shame in a British sample of females (n = 102).
Methods:
Data were collected online via Survey Monkey.
Results:
Results showed the Sexual Behaviour History (SBH) and the Hypersexual Disorder Questionnaire (HDQ) had significant positive correlation with scores on the Shame Inventory. The results indicated that hypersexual behaviours (HBI and HDQ) were able to predict a small percentage of the variability in shame once sexual orientation (heterosexual vs. non-heterosexual) and religious beliefs (belief vs. no belief) were controlled for. Results also showed there was no evidence that religious affiliation and/or religious beliefs had an influence on the levels of hypersexuality and consequences of sexual behaviours as predictors of shame.
Conclusions:
While women in the UK are rapidly shifting to a feminist way of thinking with or without technology, hypersexual disorder may often be misdiagnosed and misunderstood because of the lack of understanding and how it is conceptualised. The implications of these findings are discussed
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