421 research outputs found
A Multicamera System for Gesture Tracking With Three Dimensional Hand Pose Estimation
The goal of any visual tracking system is to successfully detect then follow an object of interest through a sequence of images. The difficulty of tracking an object depends on the dynamics, the motion and the characteristics of the object as well as on the environ ment. For example, tracking an articulated, self-occluding object such as a signing hand has proven to be a very difficult problem. The focus of this work is on tracking and pose estimation with applications to hand gesture interpretation. An approach that attempts to integrate the simplicity of a region tracker with single hand 3D pose estimation methods is presented. Additionally, this work delves into the pose estimation problem. This is ac complished by both analyzing hand templates composed of their morphological skeleton, and addressing the skeleton\u27s inherent instability. Ligature points along the skeleton are flagged in order to determine their effect on skeletal instabilities. Tested on real data, the analysis finds the flagging of ligature points to proportionally increase the match strength of high similarity image-template pairs by about 6%. The effectiveness of this approach is further demonstrated in a real-time multicamera hand tracking system that tracks hand gestures through three-dimensional space as well as estimate the three-dimensional pose of the hand
Calm Multi-Baryon Operators
Outstanding problems in nuclear physics require input and guidance from
lattice QCD calculations of few baryons systems. However, these calculations
suffer from an exponentially bad signal-to-noise problem which has prevented a
controlled extrapolation to the physical point. The variational method has been
applied very successfully to two-meson systems, allowing for the extraction of
the two-meson states very early in Euclidean time through the use of improved
single hadron operators. The sheer numerical cost of using the same techniques
in two-baryon systems has been prohibitive. We present an alternate strategy
which offers some of the same advantages as the variational method while being
significantly less numerically expensive. We first use the Matrix Prony method
to form an optimal linear combination of single baryon interpolating fields
generated from the same source and different sink interpolators. Very early in
Euclidean time this linear combination is numerically free of excited state
contamination, so we coin it a calm baryon. This calm baryon operator is then
used in the construction of the two-baryon correlation functions.
To test this method, we perform calculations on the WM/JLab iso-clover gauge
configurations at the SU(3) flavor symmetric point with m{\pi} 800 MeV
--- the same configurations we have previously used for the calculation of
two-nucleon correlation functions. We observe the calm baryon removes the
excited state contamination from the two-nucleon correlation function to as
early a time as the single-nucleon is improved, provided non-local (displaced
nucleon) sources are used. For the local two-nucleon correlation function
(where both nucleons are created from the same space-time location) there is
still improvement, but there is significant excited state contamination in the
region the single calm baryon displays no excited state contamination.Comment: 8 pages, 3 figures, proceedings for LATTICE 201
Multigrid for Chiral Lattice Fermions: Domain Wall
Critical slowing down for the Krylov Dirac solver presents a major obstacle
to further advances in lattice field theory as it approaches the continuum
solution. We propose a new multi-grid approach for chiral fermions, applicable
to both the 5-d domain wall or 4-d Overlap operator. The central idea is to
directly coarsen the 4-d Wilson kernel, giving an effective domain wall or
overlap operator on each level. We provide here an explicit construction for
the Shamir domain wall formulation with numerical tests for the 2-d Schwinger
prototype, demonstrating near ideal multi-grid scaling. The framework is
designed for a natural extension to 4-d lattice QCD chiral fermions, such as
the M\"obius, Zolotarev or Borici domain wall discretizations or directly to a
rational expansion of the 4-d Overlap operator. For the Shamir operator, the
effective overlap operator is isolated by the use of a Pauli-Villars
preconditioner in the spirit of the K\"ahler-Dirac spectral map used in a
recent staggered MG algorithm [1].Comment: 39 pages, 13 figure
Optimizing Staggered Multigrid for Exascale performance
Adaptive multi-grid methods have proven very successful in dealing with
critical slow down for the Wilson-Dirac solver in lattice gauge theory.
Multi-grid algorithms developed for Staggered fermions using the K\"ahler-Dirac
preconditioning~\cite{Brower:2018ymy} have shown remarkable success. In this
work, we discuss the performance of this staggered multi-grid algorithm in four
dimensions. We also demonstrate that offloading some components of a
multi-shift solve to a multi-grid solver leads to a significant performance
improvement in an existing MILC spectrum workflow on the Summit and Selene
supercomputers.Comment: Submission to Proceedings of Lattice 2022: the 39th International
Symposium on Lattice Field Theory, Bonn, German
Simulating the weak death of the neutron in a femtoscale universe with near-Exascale computing
The fundamental particle theory called Quantum Chromodynamics (QCD) dictates
everything about protons and neutrons, from their intrinsic properties to
interactions that bind them into atomic nuclei. Quantities that cannot be fully
resolved through experiment, such as the neutron lifetime (whose precise value
is important for the existence of light-atomic elements that make the sun shine
and life possible), may be understood through numerical solutions to QCD. We
directly solve QCD using Lattice Gauge Theory and calculate nuclear observables
such as neutron lifetime. We have developed an improved algorithm that
exponentially decreases the time-to solution and applied it on the new CORAL
supercomputers, Sierra and Summit. We use run-time autotuning to distribute GPU
resources, achieving 20% performance at low node count. We also developed
optimal application mapping through a job manager, which allows CPU and GPU
jobs to be interleaved, yielding 15% of peak performance when deployed across
large fractions of CORAL.Comment: 2018 Gordon Bell Finalist: 9 pages, 9 figures; v2: fixed 2 typos and
appended acknowledgement
The Cost Effectiveness of Psychological and Pharmacological Interventions for Social Anxiety Disorder:A Model-Based Economic Analysis
Background
Social anxiety disorder is one of the most persistent and common anxiety disorders. Individually delivered psychological therapies are the most effective treatment options for adults with social anxiety disorder, but they are associated with high intervention costs. Therefore, the objective of this study was to assess the relative cost effectiveness of a variety of psychological and pharmacological interventions for adults with social anxiety disorder.
Methods
A decision-analytic model was constructed to compare costs and quality adjusted life years (QALYs) of 28 interventions for social anxiety disorder from the perspective of the British National Health Service and personal social services. Efficacy data were derived from a systematic review and network meta-analysis. Other model input parameters were based on published literature and national sources, supplemented by expert opinion.
Results
Individual cognitive therapy was the most cost-effective intervention for adults with social anxiety disorder, followed by generic individual cognitive behavioural therapy (CBT), phenelzine and book-based self-help without support. Other drugs, group-based psychological interventions and other individually delivered psychological interventions were less cost-effective. Results were influenced by limited evidence suggesting superiority of psychological interventions over drugs in retaining long-term effects. The analysis did not take into account side effects of drugs.
Conclusion
Various forms of individually delivered CBT appear to be the most cost-effective options for the treatment of adults with social anxiety disorder. Consideration of side effects of drugs would only strengthen this conclusion, as it would improve even further the cost effectiveness of individually delivered CBT relative to phenelzine, which was the next most cost-effective option, due to the serious side effects associated with phenelzine. Further research needs to determine more accurately the long-term comparative benefits and harms of psychological and pharmacological interventions for social anxiety disorder and establish their relative cost effectiveness with greater certainty
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