14,335 research outputs found
Laser probing of the atmosphere Semiannual status report
Light backscattering experiment in laser probing studies of atmospheric layer above 100 k
Comments on Ringwood's paper 'Petrogenesis of Apollo 11 basalts and implications for lunar origin'
Apollo 11 basalt petrogenesis and theories of lunar evolution comparing lunar and earth environment
Phobos and Deimos: A base for sampling the Martian past
Future exploration of Mars is summed up by the proposal that the Martian satellites provide an ideal base for exploring the surface of Mars. For example, a manned base on Deimos could direct a series of unmanned rovers and sample recovery operations, providing an immediate feedback to the operation. Samples analyzed in such an environment would be fresh, and most importantly, would not require quarantine
Loop algebras, gauge invariants and a new completely integrable system
One fruitful motivating principle of much research on the family of
integrable systems known as ``Toda lattices'' has been the heuristic assumption
that the periodic Toda lattice in an affine Lie algebra is directly analogous
to the nonperiodic Toda lattice in a finite-dimensional Lie algebra. This paper
shows that the analogy is not perfect. A discrepancy arises because the natural
generalization of the structure theory of finite-dimensional simple Lie
algebras is not the structure theory of loop algebras but the structure theory
of affine Kac-Moody algebras. In this paper we use this natural generalization
to construct the natural analog of the nonperiodic Toda lattice. Surprisingly,
the result is not the periodic Toda lattice but a new completely integrable
system on the periodic Toda lattice phase space. This integrable system is
prescribed purely in terms of Lie-theoretic data. The commuting functions are
precisely the gauge-invariant functions one obtains by viewing elements of the
loop algebra as connections on a bundle over
Semidefinite Programming Approach for the Quadratic Assignment Problem with a Sparse Graph
The matching problem between two adjacency matrices can be formulated as the
NP-hard quadratic assignment problem (QAP). Previous work on semidefinite
programming (SDP) relaxations to the QAP have produced solutions that are often
tight in practice, but such SDPs typically scale badly, involving matrix
variables of dimension where n is the number of nodes. To achieve a speed
up, we propose a further relaxation of the SDP involving a number of positive
semidefinite matrices of dimension no greater than the number
of edges in one of the graphs. The relaxation can be further strengthened by
considering cliques in the graph, instead of edges. The dual problem of this
novel relaxation has a natural three-block structure that can be solved via a
convergent Augmented Direction Method of Multipliers (ADMM) in a distributed
manner, where the most expensive step per iteration is computing the
eigendecomposition of matrices of dimension . The new SDP
relaxation produces strong bounds on quadratic assignment problems where one of
the graphs is sparse with reduced computational complexity and running times,
and can be used in the context of nuclear magnetic resonance spectroscopy (NMR)
to tackle the assignment problem.Comment: 31 page
Nontoric Hamiltonian Circle Actions On Four-Dimensional Symplectic Orbifolds
We construct four-dimensional symplectic orbifolds admitting Hamiltonian circle actions with isolated fixed points, but not admitting any Hamiltonian action of a two-torus. One example is linear, and one example is compact
Similar Microbial Communities Found on Two Distant Seafloor Basalts.
The oceanic crust forms two thirds of the Earth's surface and hosts a large phylogenetic and functional diversity of microorganisms. While advances have been made in the sedimentary realm, our understanding of the igneous rock portion as a microbial habitat has remained limited. We present the first comparative metagenomic microbial community analysis from ocean floor basalt environments at the Lō'ihi Seamount, Hawai'i, and the East Pacific Rise (EPR; 9°N). Phylogenetic analysis indicates the presence of a total of 43 bacterial and archaeal mono-phyletic groups, dominated by Alpha- and Gammaproteobacteria, as well as Thaumarchaeota. Functional gene analysis suggests that these Thaumarchaeota play an important role in ammonium oxidation on seafloor basalts. In addition to ammonium oxidation, the seafloor basalt habitat reveals a wide spectrum of other metabolic potentials, including CO2 fixation, denitrification, dissimilatory sulfate reduction, and sulfur oxidation. Basalt communities from Lō'ihi and the EPR show considerable metabolic and phylogenetic overlap down to the genus level despite geographic distance and slightly different seafloor basalt mineralogy
Research in Atmospheric Measurement Techniques Semiannual Report
Systems analyses and models of laser techniques designed to detect interplanetary dust in atmosphere of eart
The HPV cellular transactivator Brn-3a can be used to predict cervical adenocarcinoma and squamous carcinoma precancer lesions in the developed and developing worlds
The cellular transactivator Brn-3a has previously been shown to be expressed at elevated levels in the cervix of women with squamous cell carcinoma of the cervix (SCC) and to activate the expression of HPV E6 mRNA. In this study, we show that common and rare cervical precancer lesions, including those of adenocarcinoma (AC), which are usually difficult to diagnose using classical procedures, also expressed high levels of Brn-3a and can be diagnosed by measuring the levels of Brn-3a and E6 mRNAs
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