6,672 research outputs found
Bremsstrahlung Radiation At a Vacuum Bubble Wall
When charged particles collide with a vacuum bubble, they can radiate strong
electromagnetic waves due to rapid deceleration. Owing to the energy loss of
the particles by this bremsstrahlung radiation, there is a non-negligible
damping pressure acting on the bubble wall even when thermal equilibrium is
maintained. In the non-relativistic region, this pressure is proportional to
the velocity of the wall and could have influenced the bubble dynamics in the
early universe.Comment: 6 pages, 2 figures, revtex, to appear in JKP
The Eclipsing Scuti Star EPIC 245932119
We present the physical properties of EPIC 245932119 ( = 9.82)
exhibiting both eclipses and pulsations from the {\it K{\rm 2}} photometry. The
binary modeling indicates that the eclipsing system is in detached or
semi-detached configurations with a mass ratio of 0.283 or 0.245, respectively,
and that its light-curve parameters are almost unaffected by pulsations.
Multiple frequency analyses were performed for the light residuals in the
outside-primary eclipsing phase after subtracting the binarity effects from the
observed data. We detected 35 frequencies with signal to noise amplitude ratios
larger than 4.0 in two regions of 0.626.28 day and 19.3624.07
day. Among these, it is possible that some high signals close to the
Nyquist limit may be reflections of real pulsation frequencies
(2). All frequencies (, , , ,
, ) in the lower frequency region are orbital harmonics, and
three high frequencies (, , ) appear to be sidelobes
split from the main frequency of = 22.77503 day. Most of them are
thought to be alias effects caused by the orbital frequency. For the 26 other
frequencies, the pulsation periods and pulsation constants are in the ranges of
0.0410.052 days and 0.0130.016 days, respectively. These values and the
position in the Hertzsprung-Russell diagram reveal that the primary component
is a Sct pulsator. The observational properties of EPIC 245932119 are
in good agreement with those for eclipsing binaries with Sct-type
pulsating components.Comment: 17 pages, including 5 figures and 3 tables, accepted for publication
in A
A Practical Approach to Credit Scoring
This paper proposes a DEA-based approach to credit scoring. Compared with conventional models such as multiple discriminant analysis, logistic regression analysis, and neural networks for business failure prediction, which require extra a priori information, this new approach solely requires ex-post information to calculate credit scores. For the empirical evidence, this methodology was applied to current financial data of external audited 1061 manufacturing firms comprising the credit portfolio of one of the largest credit guarantee organizations in Korea. Using financial ratios, the methodology could synthesize a firm’s overall performance into a single financial credibility score. The empirical results were also validated by supporting analyses (regression analysis and discriminant analysis) and by testing the model’s discriminatory power using actual bankruptcy cases of 103 firms. In addition, we propose a practical credit rating method using the predicted DEA scores
Twelve-spin "Schrodinger cat"
Pseudopure "cat" state, a superposition of quantum states with all spins up
and all spins down, is experimentally demonstrated for a system of twelve
dipolar-coupled nuclear spins of fully 13C-labeled benzene molecule oriented in
a liquid-crystalline matrix.Comment: Submitted to Applied Physics Letter
Interspecific competition underlying mutualistic networks
The architecture of bipartite networks linking two classes of constituents is
affected by the interactions within each class. For the bipartite networks
representing the mutualistic relationship between pollinating animals and
plants, it has been known that their degree distributions are broad but often
deviate from power-law form, more significantly for plants than animals. Here
we consider a model for the evolution of the mutualistic networks and find that
their topology is strongly dependent on the asymmetry and non-linearity of the
preferential selection of mutualistic partners. Real-world mutualistic networks
analyzed in the framework of the model show that a new animal species
determines its partners not only by their attractiveness but also as a result
of the competition with pre-existing animals, which leads to the
stretched-exponential degree distributions of plant species.Comment: 5 pages, 3 figures, accepted version in PR
Disposable Integrated Microfluidic Biochip for Blood Typing by Plastic Microinjection Moulding
Blood typing is the most important test for both transfusion recipients and blood donors. In this paper, a low cost disposable blood typing integrated microfluidic biochip has been designed, fabricated and characterized. In the biochip, flow splitting microchannels, chaotic micromixers, reaction microchambers and detection microfilters are fully integrated. The loaded sample blood can be divided by 2 or 4 equal volumes through the flow splitting microchannel so that one can perform 2 or 4 blood agglutination tests in parallel. For the purpose of obtaining efficient reaction of agglutinogens on red blood cells (RBCs) and agglutinins in serum, we incorporated a serpentine laminating micromixer into the biochip, which combines two chaotic mixing mechanisms of splitting/recombination and chaotic advection. Relatively large area reaction microchambers were also introduced for the sake of keeping the mixture of the sample blood and serum during the reaction time before filtering. The gradually decreasing multi-step detection microfilters were designed in order to effectively filter the reacted agglutinated RBCs, which show the corresponding blood group. To achieve the cost-effectiveness of the microfluidic biochip for disposability, the biochip was realized by the microinjection moulding of COC (cyclic olefin copolymer) and thermal bonding of two injection moulded COC substrates in mass production with a total fabrication time of less than 20 min. Mould inserts of the biochip for the microinjection moulding were fabricated by SU-8 photolithography and the subsequent nickel electroplating process. Human blood groups of A, B and AB have been successfully determined with the naked eye, with 3 mu l of the whole sample bloods, by means of the fabricated biochip within 3 min.X11100104sciescopu
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