8,219 research outputs found
Improved insertion-loss tester
An improved test method accurately measures the insertion loss of RF components while avoiding amplifier drift. Currents are balanced across a bridge transformer with shorted probes and then with each component to be tested. Differences in adjustments indicate the loss
Insertion loss measuring apparatus having transformer means connected across a pair of bolometers Patent
High impedance alternating current sensing transformer device between two bolometers for measuring insertion loss of test componen
A Selective Advantage for Conservative Viruses
In this letter we study the full semi-conservative treatment of a model for
the co-evolution of a virus and an adaptive immune system. Regions of viability
are calculated for both conservatively and semi-conservatively replicating
viruses interacting with a realistic semi-conservatively replicating immune
system. The conservative virus is found to have a selective advantage in the
form of an ability to survive in regions with a wider range of mutation rates
than its semi-conservative counterpart. This may help explain the existence of
a rich range of viruses with conservatively replicating genomes, a trait which
is found nowhere else in nature.Comment: 4 pages, 2 figure
Chaos driven fusion enhancement factor at astrophysical energies
We perform molecular dynamics simulations to assess the screening effects by
bound target electrons in low energy nuclear reactions in laboratories. Quantum
effects corresponding to the Pauli and Heisenberg principle are enforced by
constraints. We show that the enhancement of the average cross section and of
its variance is due to the perturbations induced by the electrons.This gives a
correlation between the maximum amplitudes of the inter-nuclear oscillational
motion and the enhancement factor. It suggests that the chaotic behavior of the
electronic motion affects the magnitude of the enhancement factor.Comment: 4 pages, 3 figure
Do columnar defects produce bulk pinning?
From magneto-optical imaging performed on heavy-ion irradiated YBaCuO single
crystals, it is found that at fields and temperatures where strong single
vortex pinning by individual irradiation-induced amorphous columnar defects is
to be expected, vortex motion is limited by the nucleation of vortex kinks at
the specimen surface rather than by half-loop nucleation in the bulk. In the
material bulk, vortex motion occurs through (easy) kink sliding. Depinning in
the bulk determines the screening current only at fields comparable to or
larger than the matching field, at which the majority of moving vortices is not
trapped by an ion track.Comment: 5 pages, 5 figures, submitted to Physical Review Letter
Solid state television camera system Patent
Solid state television camera system consisting of monolithic semiconductor mosaic sensor and molecular digital readout system
Semi-Automated SVG Programming via Direct Manipulation
Direct manipulation interfaces provide intuitive and interactive features to
a broad range of users, but they often exhibit two limitations: the built-in
features cannot possibly cover all use cases, and the internal representation
of the content is not readily exposed. We believe that if direct manipulation
interfaces were to (a) use general-purpose programs as the representation
format, and (b) expose those programs to the user, then experts could customize
these systems in powerful new ways and non-experts could enjoy some of the
benefits of programmable systems.
In recent work, we presented a prototype SVG editor called Sketch-n-Sketch
that offered a step towards this vision. In that system, the user wrote a
program in a general-purpose lambda-calculus to generate a graphic design and
could then directly manipulate the output to indirectly change design
parameters (i.e. constant literals) in the program in real-time during the
manipulation. Unfortunately, the burden of programming the desired
relationships rested entirely on the user.
In this paper, we design and implement new features for Sketch-n-Sketch that
assist in the programming process itself. Like typical direct manipulation
systems, our extended Sketch-n-Sketch now provides GUI-based tools for drawing
shapes, relating shapes to each other, and grouping shapes together. Unlike
typical systems, however, each tool carries out the user's intention by
transforming their general-purpose program. This novel, semi-automated
programming workflow allows the user to rapidly create high-level, reusable
abstractions in the program while at the same time retaining direct
manipulation capabilities. In future work, our approach may be extended with
more graphic design features or realized for other application domains.Comment: In 29th ACM User Interface Software and Technology Symposium (UIST
2016
Stochastic gain in population dynamics
We introduce an extension of the usual replicator dynamics to adaptive
learning rates. We show that a population with a dynamic learning rate can gain
an increased average payoff in transient phases and can also exploit external
noise, leading the system away from the Nash equilibrium, in a reasonance-like
fashion. The payoff versus noise curve resembles the signal to noise ratio
curve in stochastic resonance. Seen in this broad context, we introduce another
mechanism that exploits fluctuations in order to improve properties of the
system. Such a mechanism could be of particular interest in economic systems.Comment: accepted for publication in Phys. Rev. Let
Biogeochemical variations at the Porcupine Abyssal Plain sustained Observatory in the northeast Atlantic Ocean, from weekly to inter-annual timescales
We present high-resolution autonomous measurements of carbon dioxide partial pressure p(CO2) taken in situ at the Porcupine Abyssal Plain sustained Observatory (PAP-SO) in the northeast Atlantic (49° N, 16.5° W; water depth of 4850 m) for the period 2010–2012. Measurements of p(CO2) made at 30 m depth on a sensor frame are compared with other autonomous biogeochemical measurements at that depth (including chlorophyll a fluorescence and nitrate concentration data) to analyse weekly to seasonal controls on p(CO2) flux in the inter-gyre region of the North Atlantic. Comparisons are also made with in situ regional time series data from a ship of opportunity and mixed layer depth (MLD) measurements from profiling Argo floats. There is a persistent under-saturation of CO2 in surface waters throughout the year which gives rise to a perennial CO2 sink. Comparison with an earlier data set collected at the site (2003–2005) confirms seasonal and inter-annual changes in surface seawater chemistry. There is year-to-year variability in the timing of deep winter mixing and the intensity of the spring bloom.The 2010–2012 period shows an overall increase in p(CO2) values when compared to the 2003–2005 period as would be expected from increases due to anthropogenic CO2 emissions. The surface temperature, wind speed and MLD measurements are similar for both periods of time. Future work should incorporate daily CO2 flux measurements made using CO2 sensors at 1 m depth and the in situ wind speed data now available from the UK Met Office Buoy
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