6,706 research outputs found
State Space Methods in Stata
We illustrate how to estimate parameters of linear state-space models using the Stata program sspace. We provide examples of how to use sspace to estimate the parameters of unobserved-component models, vector autoregressive moving-average models, and dynamic-factor models. We also show how to compute one-step, filtered, and smoothed estimates of the series and the states; dynamic forecasts and their confidence intervals; and residuals.
On Supermultiplet Twisting and Spin-Statistics
Twisting of off-shell supermultiplets in models with 1+1-dimensional
spacetime has been discovered in 1984, and was shown to be a generic feature of
off-shell representations in worldline supersymmetry two decades later. It is
shown herein that in all supersymmetric models with spacetime of four or more
dimensions, this off-shell supermultiplet twisting, if non-trivial, necessarily
maps regular (non-ghost) supermultiplets to ghost supermultiplets. This feature
is shown to be ubiquitous in all fully off-shell supersymmetric models with
(BV/BRST-treated) constraints.Comment: Extended version, including a new section on manifestly off-shell and
supersymmetric BRST treatment of gauge symmetry; added reference
N=2 Conformal Superspace in Four Dimensions
We develop the geometry of four dimensional N=2 superspace where the entire
conformal algebra of SU(2,2|2) is realized linearly in the structure group
rather than just the SL(2,C) x U(2)_R subgroup of Lorentz and R-symmetries,
extending to N=2 our prior result for N=1 superspace. This formulation
explicitly lifts to superspace the existing methods of the N=2 superconformal
tensor calculus; at the same time the geometry, when degauged to SL(2,C) x
U(2)_R, reproduces the existing formulation of N=2 conformal supergravity
constructed by Howe.Comment: 43 pages; v2 references added, acknowledgments update
Irreducible Decomposition of Products of 10D Chiral Sigma Matrices
We review the enveloping algebra of the 10 dimensional chiral sigma matrices.
To facilitate the computation of the product of several chiral sigma matrices
we have developed a symbolic program. Using this program one can reduce the
multiplication of the sigma matrices down to linear combinations of irreducilbe
elements. We are able to quickly derive several identities that are not
restricted to traces. A copy of the program written in the Mathematica language
is provided for the community.Comment: 28 pages, Mathematica Program sigmavector10D.nb is included.
Submitted ot CP
Research to develop and define concepts for reliable control sensors - The solid state rate sensors Final report
Solid state device for sensing angular rate by detecting presence of coriolis force
Superspace Formulation in a Three-Algebra Approach to D=3, N=4,5 Superconformal Chern-Simons Matter Theories
We present a superspace formulation of the D=3, N=4,5 superconformal
Chern-Simons Matter theories, with matter supermultiplets valued in a
symplectic 3-algebra. We first construct an N=1 superconformal action, and then
generalize a method used by Gaitto and Witten to enhance the supersymmetry from
N=1 to N=5. By decomposing the N=5 supermultiplets and the symplectic 3-algebra
properly and proposing a new super-potential term, we construct the N=4
superconformal Chern-Simons matter theories in terms of two sets of generators
of a (quaternion) symplectic 3-algebra. The N=4 theories can also be derived by
requiring that the supersymmetry transformations are closed on-shell. The
relationship between the 3-algebras, Lie superalgebras, Lie algebras and
embedding tensors (proposed in [E. A. Bergshoeff, O. Hohm, D. Roest, H.
Samtleben, and E. Sezgin, J. High Energy Phys. 09 (2008) 101.]) is also
clarified. The general N=4,5 superconformal Chern-Simons matter theories in
terms of ordinary Lie algebras can be rederived in our 3-algebra approach. All
known N=4,5 superconformal Chern-Simons matter theories can be recovered in the
present superspace formulation for super-Lie-algebra realization of symplectic
3-algebras.Comment: 37 pages, minor changes, published in PR
Element-centric clustering comparison unifies overlaps and hierarchy
Clustering is one of the most universal approaches for understanding complex
data. A pivotal aspect of clustering analysis is quantitatively comparing
clusterings; clustering comparison is the basis for many tasks such as
clustering evaluation, consensus clustering, and tracking the temporal
evolution of clusters. In particular, the extrinsic evaluation of clustering
methods requires comparing the uncovered clusterings to planted clusterings or
known metadata. Yet, as we demonstrate, existing clustering comparison measures
have critical biases which undermine their usefulness, and no measure
accommodates both overlapping and hierarchical clusterings. Here we unify the
comparison of disjoint, overlapping, and hierarchically structured clusterings
by proposing a new element-centric framework: elements are compared based on
the relationships induced by the cluster structure, as opposed to the
traditional cluster-centric philosophy. We demonstrate that, in contrast to
standard clustering similarity measures, our framework does not suffer from
critical biases and naturally provides unique insights into how the clusterings
differ. We illustrate the strengths of our framework by revealing new insights
into the organization of clusters in two applications: the improved
classification of schizophrenia based on the overlapping and hierarchical
community structure of fMRI brain networks, and the disentanglement of various
social homophily factors in Facebook social networks. The universality of
clustering suggests far-reaching impact of our framework throughout all areas
of science
Use of Deeply Weathered Rock as Landfill Cover Material, Patacon Landfill, Republic of Panama
Under normal conditions weathered rock provides poor landfill cover because of its permeable nature. However, a recent hydrogeological investigation conducted by the US Army Environmental Hygiene Agency (AEHA) of the Patacon Landfill in the Republic of Panama revealed the contrary. The operators were using weathered rock from the surrounding saprolitic outcrops of the Panama formation and Tertiary andesite intrusions for landfill cover. The AEHA selected samples of the weathered rock from the borrow sites for engineering tests at their soils engineering lab at Aberdeen Proving Ground, Maryland. The following are test results. Water induces the weathered rock to slake very quickly to a gravely silt. Compaction of the samples yielded an average Proctor density of 1.74 gm/cm3 at 19 percent optimum moisture content. The lab achieved a low permeability of 6 x 10-7 cm/sec on the compacted samples. The test results suggest that properly prepared weathered rock will substitute as borrow material for landfill cover
Nonholomorphic Corrections to the One-Loop N=2 Super Yang-Mills Action
In addition to the familiar contribution from a holomorphic function \FF,
the K\"ahler potential of the scalars in the nonabelian vector multiplet
receives contributions from a real function \HH. We determine the latter at
the one-loop level, taking into account both supersymmetric matter and gauge
loops. The function \HH characterizes the four-point coupling of the
vector-multiplet vectors for constant values of their scalar superpartners. We
discuss the consequences of our results.Comment: 11 pages, Latex, one Postscript figure. Corrections to equation (24):
1 missing term added and one pair of indices interchange
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