1,633 research outputs found
Lunar orbital photogaphic planning charts for candidate Apollo J-missions
A technique is presented for minimizing Mapping Camera film usage by reducing redundant coverage while meeting the desired sidelap of greater than or equal to 55%. The technique uses the normal groundtrack separation determined as a function of the number of revolutions between the respective tracks, of the initial and final nodal azimuths (or orbital inclination), and of the lunar latitude. The technique is also applicable for planning Panoramic Camera photography such that photographic contiguity is attained but redundant coverage is minimized. Graphs are included for planning mapping camera (MC) and panoramic camera (PC) photographic passes for a specific mission (i.e., specific groundtracks) to Descartes (Apollo 16), for specific missions to potential Apollo 17 sites such as Alphonsus, Proclus, Gassendi, Davy, and Tycho, and for a potential Apollo orbit-only mission with a nodal azimuth of 85 deg. Graphs are also included for determining the maximum number of revolutions which can elapse between successive MC and PC passes, for greater than or equal 55% sidelap and rectified contiguity respectively, for nodal azimuths between 5 deg and 85 deg
Can apps support creativity in middle childhood?
This experimental study investigated whether and how creative apps may support creativity in middle childhood (n = 94 children, 8–10 years old). Guided by the moderate discrepancy hypothesis, flow theory, and the differential susceptibility to media effects model, developmentally-appropriate creative apps were predicted to increase engagement and subsequent creativity to a greater extent than developmentally-inappropriate creative apps. Furthermore, gender and fantastical thinking were predicted to moderate effects. Results provided partial support for study hypotheses. Children were more engaged when playing developmentally-appropriate apps, however, this engagement did not translate into creativity gains. Given that the data failed to support study hypotheses, post hoc analyses were conducted to explore the findings in greater detail. These additional analyses indicated that developmentally-appropriate apps not only lead to greater engagement, but were subsequently more appealing as well. These post hoc findings are discussed within the context of the study design, particularly noting that greater duration of play may be necessary to move the needle on creative skills. Empirical and practical implications are discussed
Analysis and Simulation of the Pi of the Sky Detector Response
The Pi of the Sky project observes optical flashes of astronomical origin and other light sources variable on short timescales, down to tens of seconds. We search mainly for optical emissions of Gamma Ray Bursts, but also for variable stars, blazars, etc. Precise photometry with a very large field of view (20?Ă—20?) requires a careful study and modelling of a point spread function (PSF), as presented in this paper
Fixed points of nonnegative neural networks
We consider the existence of fixed points of nonnegative neural networks,
i.e., neural networks that take as an input and produce as an output
nonnegative vectors. We first show that nonnegative neural networks with
nonnegative weights and biases can be recognized as monotonic and (weakly)
scalable functions within the framework of nonlinear Perron-Frobenius theory.
This fact enables us to provide conditions for the existence of fixed points of
nonnegative neural networks, and these conditions are weaker than those
obtained recently using arguments in convex analysis. Furthermore, we prove
that the shape of the fixed point set of nonnegative neural networks with
nonnegative weights and biases is an interval, which under mild conditions
degenerates to a point. These results are then used to obtain the existence of
fixed points of more general types of nonnegative neural networks. The results
of this paper contribute to the understanding of the behavior of autoencoders,
and they provide insight into neural networks designed using the loop-unrolling
technique, which can be seen as a fixed point searching algorithm. The chief
theoretical results of this paper are verified in numerical simulations.Comment: 34 page
Evaluation of the Audicor Acoustic Cardiography Device as a Diagnostic Tool in Horses with Mitral or Aortic Valve Insufficiency
Mitral and aortic valve insufficiencies have been commonly reported in horses. The objective of this study was to establish the use of acoustic cardiography (Audicor®) in horses with aortic (AI) or mitral valve insufficiency (MI). A total of 17 healthy horses, 18 horses with AI, and 28 horses with MI were prospectively included. None of the horses was in heart failure. Echocardiography and Audicor® analyses were conducted. Electromechanical activating time (EMAT), rate-corrected EMATc, left ventricular systolic time (LVST), rate-corrected LVSTc, and intensity and persistence of the third and fourth heart sound (S3, S4) were reported by Audicor®. Graphical analysis of the three-dimensional (3D) phonocardiogram served to visually detect murmurs. Audicor® snapshot variables were compared between groups using one-way ANOVA followed by Tukey’s multiple-comparisons test. The association between Audicor® snapshot variables and the corresponding echocardiographic variables was investigated by linear regression and Bland–Altman analyses. Heart murmurs were not displayed on Audicor® phonocardiograms. No significant differences were found between Audicor® variables obtained in clinically healthy horses and horses with valvular insufficiency. The Audicor® device is unable to detect heart murmurs in horses. Audicor® variables representing cardiac function are not markedly altered, and their association with corresponding echocardiographic variables is poor in horses with valvular insufficiency that are not in heart failure
The Synthesis of Heterocycles and Carbocycles and Work Towards Kainic Acid
This thesis focuses on the synthesis of a variety of heterocycles and carbocycles such as pyrrolidines, dihydrofurans, dihydropyrroles, cyclopentenes, and 2,5-dihydrooxepines. Traditional synthetic methods are discussed first, followed by the manipulation of donor-acceptor cyclopropanes towards the above-mentioned compounds. This leads to a discussion about an important pyrrolidine-containing natural product known as kainic acid. Kainic acid has been studied in the neuroscience field for its biological properties which have led to a better understanding of common human neurological disorders like epilepsy, Huntington’s disease and the after-effects of strokes.
Chapter two focuses on a common rearrangement of donor-acceptor cyclopropanes known as the Cloke-Wilson reaction. Without isolating the desired cyclopropane, two modes of reactivity were observed which depended solely on the choice of starting reagent. The first was the traditional Cloke-Wilson rearrangement generating dihydrofurans and the second was a vinylogous variant forming 2,5-dihydrooxepines. It was discovered that with careful choice of Lewis acid or transition metal catalysts, each of the obtained compounds can be manipulated to other dihydrofuran derivatives or dihydropyrrole heterocycles. One of the dihydropyrrole compounds obtained was deemed as a viable synthetic precursor towards kainic acid.
Chapter three describes the synthetic efforts towards kainic acid utilizing the methodology from chapter two. The difficulties towards this natural molecule will be presented with the major issue resulting from stereochemical constraints. This resulted in the successful synthesis of β-allokainic acid which is one of the less active isomers of naturally occurring kainic acid.
Chapter four discloses a single-step manipulation of the dihydrofurans synthesized via Cloke-Wilson rearrangement to their corresponding cyclopentenes. Extensive screening of Lewis acids and solvents provided insights into the possible mechanism of this reaction
Inverse Solvability and Security with Applications to Federated Learning
We introduce the concepts of inverse solvability and security for a generic
linear forward model and demonstrate how they can be applied to models used in
federated learning. We provide examples of such models which differ in the
resulting inverse solvability and security as defined in this paper. We also
show how the large number of users participating in a given iteration of
federated learning can be leveraged to increase both solvability and security.
Finally, we discuss possible extensions of the presented concepts including the
nonlinear case
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