1,690 research outputs found
Signatures of restarted activity in core-dominated, triple radio sources selected from the FIRST survey
Signatures of the re-occurrence of activity in radio-loud AGNs, indicated
either by the so-called double-double or X-shaped structures, have been
observed in a number of radio sources. All such objects known to date have
linear sizes of the order of a megaparsec. A number of the sources that are
appreciably more compact than this, but that exhibit hints of a past phase of
activity, were found in the VLA FIRST survey. Their structures show symmetric
relic lobes straddling relatively bright, unresolved cores. Observations of the
cores of 15 such structures with MERLIN at 5 GHz have shown that four of them
are doubles or core-jets on the subarcsecond scale. Misalignments of \Delta PA
\ga 30 degr. between the axis of the inner structure and the line connecting
the fitted maxima of the arcminute-scale relic lobes are clearly visible in
three of the four sources. From these results, we can infer that a rapid
repositioning of the central engine in each of these three radio sources is the
most plausible interpretation of the observed morphology and that a merger is
most likely the original cause of such a repositioning. In the case of TXS
1033+026, the optical image extracted from the SDSS archives clearly suggests
that two objects separated by only 2.7 kpc (projected onto the sky plane) are
indeed merging. The inner parts of TXS 0818+214 and TXS 1312+563 could be
interpreted as double-lobed, and consequently, these sources could be of the
double-double type; but further multifrequency observations are necessary to
provide support for such an interpretation.Comment: 9 pages, 5 figures, matches the version printed in Astronomy &
Astrophysics, very minor correction of Table
Simulation of fluid flow in hydrophobic rough microchannels
Surface effects become important in microfluidic setups because the surface
to volume ratio becomes large. In such setups the surface roughness is not any
longer small compared to the length scale of the system and the wetting
properties of the wall have an important influence on the flow. However, the
knowledge about the interplay of surface roughness and hydrophobic
fluid-surface interaction is still very limited because these properties cannot
be decoupled easily in experiments.
We investigate the problem by means of lattice Boltzmann (LB) simulations of
rough microchannels with a tunable fluid-wall interaction. We introduce an
``effective no-slip plane'' at an intermediate position between peaks and
valleys of the surface and observe how the position of the wall may change due
to surface roughness and hydrophobic interactions.
We find that the position of the effective wall, in the case of a Gaussian
distributed roughness depends linearly on the width of the distribution.
Further we are able to show that roughness creates a non-linear effect on the
slip length for hydrophobic boundaries.Comment: 10 pages, 5 figure
RSFQ devices with selective dissipation for quantum information processing
We study the possibility to use frequency dependent damping in RSFQ circuits
as means to reduce dissipation and consequent decoherence in RSFQ/qubit
circuits. We show that stable RSFQ operation can be achieved by shunting the
Josephson junctions with an circuit instead of a plain resistor. We derive
criteria for the stability of such an arrangement, and discuss the effect on
decoherence and the optimisation issues. We also design a simple flux generator
aimed at manipulating flux qubits
The ascorbate-glutathione cycle coming of age
Concepts, regarding the operation of the ascorbate/glutathione cycle and the associated water/water cycle in the processing of metabolically-generated hydrogen peroxide and other forms of reactive oxygen species (ROS), are well established in the literature. However, our knowledge of functions of these cycles and their component enzymes continues to grow and evolve. Recent insights include participation in the intrinsic environmental and developmental signaling pathways that regulate plant growth, development and defense. In addition to ROS processing, the enzymes of the two cycles not only support the functions of ascorbate and glutathione, they also have "moonlighting" functions. They are subject to post-translational modifications and have an extensive interactome, particularly with other signaling proteins. In this assessment of current knowledge, we highlight the central position of the ascorbate/glutathione cycle in the network of cellular redox systems that underpin the energy-sensitive communication within the different cellular compartments and integrate plant signalling pathways.</p
Aspectos hormonais, bioquĂmicos e hematolĂłgicos de prĂ© e pĂłs-parto de suĂnos.
bitstream/item/84751/1/DCOT-045.pd
Lattice Boltzmann simulations of apparent slip in hydrophobic microchannels
Various experiments have found a boundary slip in hydrophobic microchannel
flows, but a consistent understanding of the results is still lacking. While
Molecular Dynamics (MD) simulations cannot reach the low shear rates and large
system sizes of the experiments, it is often impossible to resolve the needed
details with macroscopic approaches. We model the interaction between
hydrophobic channel walls and a fluid by means of a multi-phase lattice
Boltzmann model. Our mesoscopic approach overcomes the limitations of MD
simulations and can reach the small flow velocities of known experiments. We
reproduce results from experiments at small Knudsen numbers and other
simulations, namely an increase of slip with increasing liquid-solid
interactions, the slip being independent of the flow velocity, and a decreasing
slip with increasing bulk pressure. Within our model we develop a semi-analytic
approximation of the dependence of the slip on the pressure.Comment: 7 pages, 4 figure
A multinomial model for the quality control of colony counting procedures
The so-called good-laboratory-practice (GLP) test provides an experimental design and appropriate statistical analysis for the problem of analyst performance assessment in microbiological laboratories. For a given sample material multiple dilution series are generated yielding colony counts from several dilution levels. Statistical evaluation is based on the assumption of Poisson-distributed colony forming units. In this paper a new model based on conditional binomial and multinomial distributions is presented and it is shown how it is related to the standard model which assumes Poisson-distributed colony counts. The effects of common working errors on the statistical evaluation of the GLP-test are investigated
A Multinomial Model for the Quality Control of Colony Counting Procedures
The so-called good-laboratory-practice (GLP) test provides an experimental design and appropriate statistical analysis for the problem of analyst performance assessment in microbiological laboratories. For a given sample material multiple dilution series are generated yielding colony counts from several dilution levels. Statistical evaluation is based on the assumption of Poisson-distributed colony forming units. In this paper a new model based on conditional binomial and multinomial distributions is presented and it is shown how it is related to the standard model which assumes Poisson-distributed colony counts. The effects of common working errors on the statistical evaluation of the GLP-test are investigated
Realization of a classical counterpart of a scalable design for adiabatic quantum computation
We implement a classical counterpart of a scalable design for adiabatic
quantum computation. The key element of this design is a coupler providing
controllable coupling between two bistable elements (in our case
superconducting rings with a single Josephson junction playing the role of a
classical counterpart of superconducting flux qubits) The coupler is also a
superconducting ring with a single Josephson junction that operates in the
non-hysteretic mode. The flux coupling between two bistable rings can be
controlled by changing the magnetic flux through the coupler. Thereby, the
coupling can be tuned from ferromagnetic trough zero to to anti-ferromagnetic.Comment: 3 pages, 3 figures v2: extended discussion experimental result
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