14,476 research outputs found
Simultaneous message framing and error detection
Circuitry simultaneously inserts message framing information and detects noise errors in binary code data transmissions. Separate message groups are framed without requiring both framing bits and error-checking bits, and predetermined message sequence are separated from other message sequences without being hampered by intervening noise
El Hermanito: El Niño's overlooked little brother in the Atlantic
An oscillation with a period of about 30 months has been identified in the equatorial Atlantic by analyzing sea surface temperature (SST) observations for the period 1949-1991. The 30-month time scale was also found in numerical simulations with an atmospheric general circulation model (AGCM) that was forced by these SSTs and a coupled ocean atmosphere general circulation model (CGCM). Consistent with the theory of tropical air-sea interactions, the Atlantic oscillation (El Hermanito) is an inherently coupled air-sea mode and can be viewed as the Atlantic analogon of the El Nino/Southern Oscillation (ENSO) phenomenon in the equatorial Pacific. El Hermanito is an internal Atlantic mode and appears to be independent of the quasi-biennial (QB) variability observed in the tropical Indian and Pacific Oceans. The discovery of El Hermanito is important to the prediction of Atlantic climate anomalies. (orig.
Current reversal and exclusion processes with history-dependent random walks
A class of exclusion processes in which particles perform history-dependent
random walks is introduced, stimulated by dynamic phenomena in some biological
and artificial systems. The particles locally interact with the underlying
substrate by breaking and reforming lattice bonds. We determine the
steady-state current on a ring, and find current-reversal as a function of
particle density. This phenomenon is attributed to the non-local interaction
between the walkers through their trails, which originates from strong
correlations between the dynamics of the particles and the lattice. We
rationalize our findings within an effective description in terms of
quasi-particles which we call front barriers. Our analytical results are
complemented by stochastic simulations.Comment: 5 pages, 6 figure
Designing experiments for an application in laser and surface Chemistry
We consider the design used to collect data for a Second Harmonic Generation (SHG) experiment, where the behaviour of interfaces between two phases, for example the surface of a liquid, is investigated. These studies have implications in surfactants, catalysis, membranes and electrochemistry. Ongoing work will be described in designing experiments to investigate nonlinear models used to represent the data, relating the intensity of the SHG signal to the polarisation angles of the polarised light beam. The choice of design points and their effect on parameter estimates is investigated. Various designs and the current practice of using equal-spaced levels are investigated, and their relative merits compared on the basis of the overall aim of the chemical study
The use of happiness research for public policy
Research on happiness tends to follow a "benevolent dictator" approach where politicians pursue people's happiness. This paper takes an antithetic approach based on the insights of public choice theory. First, we inquire how the results of happiness research may be used to improve the choice of institutions. Second, we show that the policy approach matters for the choice of research questions and the kind of knowledge happiness research aims to provide. Third, we emphasize that there is no shortcut to an optimal policy maximizing some happiness indicator or social welfare function since governments have an incentive to manipulate this indicator
Bolometric and UV Light Curves of Core-Collapse Supernovae
The Swift UV-Optical Telescope (UVOT) has been observing Core-Collapse
Supernovae (CCSNe) of all subtypes in the UV and optical since 2005. We present
here 50 CCSNe observed with the Swift UVOT, analyzing their UV properties and
behavior. Where we have multiple UV detections in all three UV filters (\lambda
c = 1928 - 2600 \AA), we generate early time bolometric light curves, analyze
the properties of these light curves, the UV contribution to them, and derive
empirical corrections for the UV-flux contribution to optical-IR based
bolometric light curves
Optimal flexibility for conformational transitions in macromolecules
Conformational transitions in macromolecular complexes often involve the
reorientation of lever-like structures. Using a simple theoretical model, we
show that the rate of such transitions is drastically enhanced if the lever is
bendable, e.g. at a localized "hinge''. Surprisingly, the transition is fastest
with an intermediate flexibility of the hinge. In this intermediate regime, the
transition rate is also least sensitive to the amount of "cargo'' attached to
the lever arm, which could be exploited by molecular motors. To explain this
effect, we generalize the Kramers-Langer theory for multi-dimensional barrier
crossing to configuration dependent mobility matrices.Comment: 4 pages, 4 figure
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