43,299 research outputs found
Guidance, flight mechanics and trajectory optimization. Volume 4 - The calculus of variations and modern applications
Guidance, flight mechanics, and trajectory optimization - calculus of variations and modern application
Fluorescence antibunching microscopy
Breaking the diffraction limit in microscopy by utilizing quantum properties
of light has been the goal of intense research in the recent years. We propose
a quantum superresolution technique based on non-classical emission statistics
of fluorescent markers, routinely used as contrast labels for bio-imaging. The
technique can be readily implemented using standard fluorescence microscopy
equipment
Dynamical Inequality in Growth Models
A recent exponent inequality is applied to a number of dynamical growth
models. Many of the known exponents for models such as the Kardar-Parisi-Zhang
(KPZ) equation are shown to be consistent with the inequality. In some cases,
such as the Molecular Beam Equation, the situation is more interesting, where
the exponents saturate the inequality. As the acid test for the relative
strength of four popular approximation schemes we apply the inequality to the
exponents obtained for two Non Local KPZ systems. We find that all methods but
one, the Self Consistent Expansion, violate the inequality in some regions of
parameter space. To further demonstrate the usefulness of the inequality, we
apply it to a specific model, which belongs to a family of models in which the
inequality becomes an equality. We thus show that the inequality can easily
yield results, which otherwise have to rely either on approximations or general
beliefs.Comment: 6 pages, 4 figure
The structure of Herbig-Haro object 43 and Orion dark cloud extinction
New ultraviolet and optical observations of Herbig-Haro Object No. 43 are reported. Continuum and emission line fluxes in the range 1250 A equal to or less than lambda equal to less than 7350A have been measured. The continuum fluxes are best matched by an enhanced H two photon component added to H free bound emission, assuming theta Ori extinction curve with E(B-V) = 0.2, R = 5. The strucutre and dynamics of three components within the object are discussed. The object has a radiative output of equal to or greater than 0.23 infrared luminosity in ultraviolet and optical radiation combined. The energy requirements are discussed in terms of the production of shock waves by a collimated, supersonic mass outflow from a nearby infrared source
Numerical study of the transition of the four dimensional Random Field Ising Model
We study numerically the region above the critical temperature of the four
dimensional Random Field Ising Model. Using a cluster dynamic we measure the
connected and disconnected magnetic susceptibility and the connected and
disconnected overlap susceptibility. We use a bimodal distribution of the field
with for all temperatures and a lattice size L=16. Through a
least-square fit we determine the critical exponents and . We find the magnetic susceptibility and the overlap
susceptibility diverge at two different temperatures. This is coherent with the
existence of a glassy phase above . Accordingly with other simulations
we find . In this case we have a scaling theory with
two indipendet critical exponentsComment: 10 pages, 2 figures, Late
Novel applications of the NASA/GSFC Viterbi decoder hardware simulator
The NASA/GSFC developed an all digital, real time, programmable Viterbi decoder simulator operating at rates up to 6 Msps. With this simulator, the bit error rate (BER) performance of convolutionally encoded/Viterbi decoded Shuttle-TDRSS return link channels under pulsed radio frequency interference (RFI) conditions has been predicted. The principles of the simulator are described with special emphasis on the channel simulator and the essential interaction between CLASS software and the simulator. The sensitivity of coded BER as function of several illustrative RFI parameters is discussed for two typical Shuttle-TDRSS return link configurations
Learning to Classify from Impure Samples with High-Dimensional Data
A persistent challenge in practical classification tasks is that labeled
training sets are not always available. In particle physics, this challenge is
surmounted by the use of simulations. These simulations accurately reproduce
most features of data, but cannot be trusted to capture all of the complex
correlations exploitable by modern machine learning methods. Recent work in
weakly supervised learning has shown that simple, low-dimensional classifiers
can be trained using only the impure mixtures present in data. Here, we
demonstrate that complex, high-dimensional classifiers can also be trained on
impure mixtures using weak supervision techniques, with performance comparable
to what could be achieved with pure samples. Using weak supervision will
therefore allow us to avoid relying exclusively on simulations for
high-dimensional classification. This work opens the door to a new regime
whereby complex models are trained directly on data, providing direct access to
probe the underlying physics.Comment: 6 pages, 2 tables, 2 figures. v2: updated to match PRD versio
Pileup Mitigation with Machine Learning (PUMML)
Pileup involves the contamination of the energy distribution arising from the
primary collision of interest (leading vertex) by radiation from soft
collisions (pileup). We develop a new technique for removing this contamination
using machine learning and convolutional neural networks. The network takes as
input the energy distribution of charged leading vertex particles, charged
pileup particles, and all neutral particles and outputs the energy distribution
of particles coming from leading vertex alone. The PUMML algorithm performs
remarkably well at eliminating pileup distortion on a wide range of simple and
complex jet observables. We test the robustness of the algorithm in a number of
ways and discuss how the network can be trained directly on data.Comment: 20 pages, 8 figures, 2 tables. Updated to JHEP versio
The Upper Limit Solar Gamma-ray Spectrum to 10 Mev
Balloon flight data on upper limit solar gamma ray spectrum from quiet su
Energy conditions for a generally coupled scalar field outside a reflecting sphere
We calculate the stress-energy tensor for a scalar field with general
curvature coupling, outside a perfectly reflecting sphere with Dirichlet
boundary conditions. For conformal coupling we find that the null energy
condition is always obeyed, and therefore the averaged null energy condition
(ANEC) is also obeyed. Since the ANEC is independent of curvature coupling, we
conclude that the ANEC is obeyed for scalar fields with any curvature coupling
in this situation. We also show how the spherical case goes over to that of a
flat plate as one approaches the sphere.Comment: Accepted for publication in Phys. Rev.
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