3,360 research outputs found
Integrating business and personal income taxes
An examination of the problems surrounding the current corporate tax system, including a detailed look at several reform proposals from the Treasury Department.Corporations - Taxation ; Income tax
Parallel Quantum-Point-Contacts as High-Frequency-Mixers
We present the results of high-frequency mixing experiments performed upon
parallel quantum point-contacts defined in the two-dimensional electron gas of
an Al_{x}Ga_{1-x}As/GaAs-heterostructure. The parallel geometry, fabricated
using a novel double-resist technology, enables the point-contact device to be
impedance matched over a wide frequency range and, in addition, increases the
power levels of the mixing signal while simultaneously reducing the parasitic
source-drain capacitance. Here, we consider two parallel quantum point-contact
devices with 155 and 110 point-contacts respectively; both devices operated
successfully at liquid helium and liquid nitrogen temperatures with a minimal
conversion loss of 13 dB.Comment: 4 figures, RevTeX, to be published in the 16 June 1997 issue of
Applied Physic Letter
Molecular mechanism of influenza A NS1-mediated TRIM25 recognition and inhibition
RIG-I is a viral RNA sensor that induces the production of type I interferon (IFN) in response to infection with a variety of viruses. Modification of RIG-I with K63-linked poly-ubiquitin chains, synthesised by TRIM25, is crucial for activation of the RIG-I/MAVS signalling pathway. TRIM25 activity is targeted by influenza A virus non-structural protein 1 (NS1) to suppress IFN production and prevent an efficient host immune response. Here we present structures of the human TRIM25 coiled-coil-PRYSPRY module and of complexes between the TRIM25 coiled-coil domain and NS1. These structures show that binding of NS1 interferes with the correct positioning of the PRYSPRY domain of TRIM25 required for substrate ubiquitination and provide a mechanistic explanation for how NS1 suppresses RIG-I ubiquitination and hence downstream signalling. In contrast, the formation of unanchored K63-linked poly-ubiquitin chains is unchanged by NS1 binding, indicating that RING dimerisation of TRIM25 is not affected by NS1
Time series aggregation, disaggregation and long memory
We study the aggregation/disaggregation problem of random parameter AR(1)
processes and its relation to the long memory phenomenon. We give a
characterization of a subclass of aggregated processes which can be obtained
from simpler, "elementary", cases. In particular cases of the mixture
densities, the structure (moving average representation) of the aggregated
process is investigated
Feedback-Optimized Operations with Linear Ion Crystals
We report on transport operations with linear crystals of 40Ca+ ions by
applying complex electric time-dependent potentials. For their control we use
the information obtained from the ions' fluorescence. We demonstrate that by
means of this feedback technique, we can transport a predefined number of ions
and also split and unify ion crystals. The feedback control allows for a robust
scheme, compensating for experimental errors as it does not rely on a precisely
known electrical modeling of the electric potentials in the ion trap
beforehand. Our method allows us to generate a self-learning voltage ramp for
the required process. With an experimental demonstration of a transport with
more than 99.8 % success probability, this technique may facilitate the
operation of a future ion based quantum processor
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