16,002 research outputs found
The synthesis of some acylglycines and related oxazolones
No description supplie
Control system for hunger and its implications in animals and man
No description supplie
Optimized Coplanar Waveguide Resonators for a Superconductor-Atom Interface
We describe the design and characterization of superconducting coplanar
waveguide cavities tailored to facilitate strong coupling between
superconducting quantum circuits and single trapped Rydberg atoms. For initial
superconductor-atom experiments at 4.2 K, we show that resonator quality
factors above can be readily achieved. Furthermore, we demonstrate that
the incorporation of thick-film copper electrodes at a voltage antinode of the
resonator provides a route to enhance the zero-point electric fields of the
resonator in a trapping region that is 40 m above the chip surface,
thereby minimizing chip heating from scattered trap light. The combination of
high resonator quality factor and strong electric dipole coupling between the
resonator and the atom should make it possible to achieve the strong coupling
limit of cavity quantum electrodynamics with this system.Comment: 4 pages, 4 figure
Synthesis of hetero-bifunctional, end-capped oligo-EDOT derivatives
Conjugated oligomers of 3,4-ethylenedioxythiophene (EDOT) are attractive materials for tissue engineering applications, and as model systems for studying the properties of the widely used polymer PEDOT. We report here the facile synthesis of a series of keto-acid end-capped oligo-EDOT derivatives (n = 2-7) through a combination of a glyoxylation end capping strategy and iterative direct arylation chain extension. Importantly, these structures not only represent the longest oligo-EDOTs reported, but are also bench stable in contrast to previous reports on such oligomers. The constructs reported here can undergo subsequent derivatization for integration into higher order architectures, such as those required for tissue engineering applications. The synthesis of hetero-bifunctional constructs, as well as those containing mixed monomer units is also reported, allowing further complexity to be installed in a controlled manner. Finally, we describe the optical and electrochemical properties of these oligomers and demonstrate the importance of the keto-acid in determining their characteristics
Black hole boundaries
Classical black holes and event horizons are highly non-local objects,
defined in relation to the causal past of future null infinity. Alternative,
quasilocal characterizations of black holes are often used in mathematical,
quantum, and numerical relativity. These include apparent, killing, trapping,
isolated, dynamical, and slowly evolving horizons. All of these are closely
associated with two-surfaces of zero outward null expansion. This paper reviews
the traditional definition of black holes and provides an overview of some of
the more recent work on alternative horizons.Comment: 27 pages, 8 figures, invited Einstein Centennial Review Article for
CJP, final version to appear in journal - glossary of terms added, typos
correcte
Self-contained Kondo effect in single molecules
Kondo coupling of f and conduction electrons is a common feature of
f-electron intermetallics. Similar effects should occur in carbon ring
systems(metallocenes). Evidence for Kondo coupling in Ce(C8H8)2 (cerocene) and
the ytterbocene Cp*2Yb(bipy) is reported from magnetic susceptibility and
L_III-edge x-ray absorption spectroscopy. These well-defined systems provide a
new way to study the Kondo effect on the nanoscale, should generate insight
into the Anderson Lattice problem, and indicate the importance of this
often-ignored contribution to bonding in organometallics.Comment: 4 pages, 5 figures (eps
Hypergraph Acyclicity and Propositional Model Counting
We show that the propositional model counting problem #SAT for CNF- formulas
with hypergraphs that allow a disjoint branches decomposition can be solved in
polynomial time. We show that this class of hypergraphs is incomparable to
hypergraphs of bounded incidence cliquewidth which were the biggest class of
hypergraphs for which #SAT was known to be solvable in polynomial time so far.
Furthermore, we present a polynomial time algorithm that computes a disjoint
branches decomposition of a given hypergraph if it exists and rejects
otherwise. Finally, we show that some slight extensions of the class of
hypergraphs with disjoint branches decompositions lead to intractable #SAT,
leaving open how to generalize the counting result of this paper
SPS phase control system performance via analytical simulation
A solar power satellite transmission system which incorporates automatic beam forming, steering, and phase control is discussed. The phase control concept centers around the notation of an active retrodirective phased array as a means of pointing the beam to the appropriate spot on Earth. The transmitting antenna (spacetenna) directs the high power beam so that it focuses on the ground-based receiving antenna (rectenna). A combination of analysis and computerized simulation was conducted to determine the far field performance of the reference distribution system, and the beam forming and microwave power generating systems
P and T Violation From Certain Dimension Eight Weinberg Operators
Dimension eight operators of the Weinberg type have been shown to give
important contributions to CP violating phenomena, such as the electric dipole
moment of the neutron. In this note we show how operators related to these (and
expected to occur on equal footing) can give rise to time-reversal violating
phenomena such as atomic electric dipole moments. We also estimate the induced
parity violating phenomena such as small ``wrong'' parity admixtures in atomic
states and find that they are negligible. Uses harvmac.tex and epsf.tex; one
figure submitted as a uuencoded, compressed EPS file.Comment: 6 pages, EFI-92-5
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