5,803 research outputs found
Capillary focusing close to a topographic step: Shape and instability of confined liquid filaments
Step-emulsification is a microfluidic technique for droplet generation which
relies on the abrupt decrease of confinement of a liquid filament surrounded by
a continuous phase. A striking feature of this geometry is the transition
between two distinct droplet breakup regimes, the "step-regime" and
"jet-regime", at a critical capillary number. In the step-regime, small and
monodisperse droplets break off from the filament directly at a topographic
step, while in the jet-regime a jet protrudes into the larger channel region
and large plug-like droplets are produced. We characterize the breakup behavior
as a function of the filament geometry and the capillary number and present
experimental results on the shape and evolution of the filament for a wide
range of capillary numbers in the jet-regime. We compare the experimental
results with numerical simulations. Assumptions based on the smallness of the
depth of the microfluidic channel allow to reduce the governing equations to
the Hele-Shaw problem with surface tension. The full nonlinear equations are
then solved numerically using a volume-of-fluid based algorithm. The
computational framework also captures the transition between both regimes,
offering a deeper understanding of the underlying breakup mechanism
A digital simulation of message traffic for natural disaster warning communications satellite
Various types of weather communications are required to alert industries and the general public about the impending occurrence of tornados, hurricanes, snowstorms, floods, etc. A natural disaster warning satellite system has been proposed for meeting the communications requirements of the National Oceanic and Atmospheric Administration. Message traffic for a communications satellite was simulated with a digital computer in order to determine the number of communications channels to meet system requirements. Poisson inputs are used for arrivals and an exponential distribution is used for service
Bipartite all-versus-nothing proofs of Bell's theorem with single-qubit measurements
If we distribute n qubits between two parties, which quantum pure states and
distributions of qubits would allow all-versus-nothing (or
Greenberger-Horne-Zeilinger-like) proofs of Bell's theorem using only
single-qubit measurements? We show a necessary and sufficient condition for the
existence of these proofs for any number of qubits, and provide all distinct
proofs up to n=7 qubits. Remarkably, there is only one distribution of a state
of n=4 qubits, and six distributions, each for a different state of n=6 qubits,
which allow these proofs.Comment: REVTeX4, 4 pages, 2 figure
Irreversibility line and low-field grain-boundary pinning in electron-doped superconducting thin films
AC magnetic susceptibilities of electron-doped Pr_{1.85}Ce_{0.15}CuO_4 (PCCO)
and Sm_{1.85}Ce_{0.15}CuO_4 (SCCO) granular thin films have been measured as a
function of temperature and magnetic-field strength. Depending on the level of
homogeneity of our films, two different types of the irreversibility line (IL)
defined as the intergrain-loss peak temperature in the imaginary part of
susceptibility have been found. The obtained results are described via the
critical-state model taking into account the low-field grain-boundary pinning.
The extracted pinning-force densities in more granular SCCO films turn out to
be four times larger than their counterparts in less granular PCCO films
DC-assisted microwave quenching of YBa2Cu3O7-{\delta} coplanar waveguide to a highly dissipative state
The paper reports on finding the effect of a strong change in the microwave
losses in an HTS-based coplanar waveguide (CPW) at certain values of the input
power Pin and direct current Idc. CPW on the basis of 150 nm thick
YBa2Cu3O7-{\delta} epitaxial film on a single crystal MgO substrate was studied
experimentally. A sharp and reversible transition of the CPW into a strongly
dissipative state at the certain meanings of Pin and Idc depending on
temperature was observed. Apparently the effect can be explained by
self-heating of HTS structure caused by magnetic flux flow under the joint
influence of MW and DC.Comment: 9 pages, 5 figures, 17 reference
YBCO microwave resonators for strong collective coupling with spin ensembles
Coplanar microwave resonators made of 330 nm-thick superconducting YBCO have
been realized and characterized in a wide temperature (, 2-100 K) and
magnetic field (, 0-7 T) range. The quality factor exceeds 10
below 55 K and it slightly decreases for increasing fields, remaining 90 of
for T and K. These features allow the coherent coupling
of resonant photons with a spin ensemble at finite temperature and magnetic
field. To demonstrate this, collective strong coupling was achieved by using
DPPH organic radical placed at the magnetic antinode of the fundamental mode:
the in-plane magnetic field is used to tune the spin frequency gap splitting
across the single-mode cavity resonance at 7.75 GHz, where clear anticrossings
are observed with a splitting as large as MHz at K. The
spin-cavity collective coupling rate is shown to scale as the square root of
the number of active spins in the ensemble.Comment: to appear in Appl. Phys. Let
Uncertainty-Aware Organ Classification for Surgical Data Science Applications in Laparoscopy
Objective: Surgical data science is evolving into a research field that aims
to observe everything occurring within and around the treatment process to
provide situation-aware data-driven assistance. In the context of endoscopic
video analysis, the accurate classification of organs in the field of view of
the camera proffers a technical challenge. Herein, we propose a new approach to
anatomical structure classification and image tagging that features an
intrinsic measure of confidence to estimate its own performance with high
reliability and which can be applied to both RGB and multispectral imaging (MI)
data. Methods: Organ recognition is performed using a superpixel classification
strategy based on textural and reflectance information. Classification
confidence is estimated by analyzing the dispersion of class probabilities.
Assessment of the proposed technology is performed through a comprehensive in
vivo study with seven pigs. Results: When applied to image tagging, mean
accuracy in our experiments increased from 65% (RGB) and 80% (MI) to 90% (RGB)
and 96% (MI) with the confidence measure. Conclusion: Results showed that the
confidence measure had a significant influence on the classification accuracy,
and MI data are better suited for anatomical structure labeling than RGB data.
Significance: This work significantly enhances the state of art in automatic
labeling of endoscopic videos by introducing the use of the confidence metric,
and by being the first study to use MI data for in vivo laparoscopic tissue
classification. The data of our experiments will be released as the first in
vivo MI dataset upon publication of this paper.Comment: 7 pages, 6 images, 2 table
Emergence of the Shackleton Range from beneath the Antarctic Ice Sheet due to glacial erosion
This paper explores the long-term evolution of a subglacial fjord landscape in the Shackleton Range, Antarctica. We propose that prolonged ice-sheet erosion across a passive continental margin caused troughs to deepen and lower the surrounding ice-sheet surface, leaving adjacent mountains exposed. Geomorphological evidence suggests a change in the direction of regional ice flow accompanied emergence. Simple calculations suggest that isostatic compensation caused by the deepening of bounding ice-stream troughs lowered the ice-sheet surface relative to the mountains by ~800m. Use of multiple cosmogenic isotopes on bedrock and erratics (26Al, 10Be, 21Ne) provides evidence that overriding of the massif and the deepening of the adjacent troughs occurred earlier than the Quaternary. Perhaps this occurred in the mid-Miocene, as elsewhere in East Antarctica in the McMurdo Dry Valleys and the Lambert basin. The implication is that glacial erosion instigates feedback that can change ice-sheet thickness, extent, and direction of flow. Indeed, as the subglacial troughs evolve over millions of years, they increase topographic relief; and this changes the dynamics of the ice sheet. © 2013 Elsevier B.V
- …