50,594 research outputs found
Faddeev-Skyrme Model and Rational Maps
The Faddeev-Skyrme model, a modified O(3) nonlinear sigma model in three
space dimensions, is known to admit topological solitons that are stabilized by
the Hopf charge. The Faddeev-Skyrme model is also related to the low-energy
limits of SU(2) Yang-Mills theory. Here, the model is reformulated into its
gauge-equivalent expression, which turns out to be Skyrme-like. The solitonic
solutions of this Skyrme-like model are analyzed by the rational map ansatz.
The energy function and the Bogomolny-type lower bound of the energy are
established. The generalized Faddeev-Skyrme model that originates from the
infrared limits of SU(N) Yang-Mills theory is presented.Comment: 12 pages, LaTex, minor typo correcte
Are Real Exchange Rates Nonlinear with a Unit Root? Evidence on Purchasing Power Parity for China: A Note
This article applies the threshold autoregressive model proposed by Caner and Hansen (2001) to examine both linearity and stationarity of China's real exchange rate vis-Ã -vis her 9 trading partner countries over the period of January 1986 to October 2009. Two main conclusions are drawn. Firstly, the empirical results indicate that China's real exchange is a nonlinear process. Secondly, a unit root in real exchange rate was found for most of the cases under study. This result provides no support for purchasing power parity for China relative to their major trading partner countries.Threshold Autoregressive Model; Linearity and Stationarity, Purchasing Power Parity; Threshold Unit Root Test
The Lending-Deposit Rate Relationship in Eastern European Countries: Evidence from the Rank Test for Non-linear Cointegration
This study carries out an examination of the potential non-linear cointegration between the lending and deposit rates of eight Eastern European countries using the non-parametric rank tests proposed by Breitung (2001). Based upon our adoption in this study of the threshold error-correction model (TECM), we find solid evidence of an asymmetric price transmission effect, in both the short term and the long term, between lending and deposit rates. Thus, our results reveal that there are indeed such long-run non-linear cointegration relationships between the lending and deposit rates in these Eastern European countries. Furthermore, we go on to successfully capture the dynamic adjustment of the spread.lending-deposit rates, rank test, non-linearity
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Cost-Effectiveness of Advanced Imaging Technologies in the Presurgical Workup of Epilepsy.
The cost-effectiveness and benefit of many diagnostic tests used in the presurgical evaluation for persons with epilepsy is for the most part uncertain as is their influence on decision-making. The options we have at our disposal are ever increasing. Advanced imaging modalities aim to improve surgical candidacy by helping us better define the epileptogenic zone and optimize surgical planning. However, judicious use is important. Randomized controlled trials delineating which mode of investigation is superior are lacking. Presurgical tests do have incremental value by increasing surgical candidacy and refining surgical planning. The yield of additional imaging will increase with complex localization. However, every case must be tailored by hypothesis, cost, and accessibility. Future studies using a quantitative cost-benefit framework are needed to determine the cost-effectiveness of advanced diagnostic tests (beyond magnetic resonance imaging) in the presurgical evaluation of those with epilepsy
Optimization of Bi-Directional V2G Behavior With Active Battery Anti-Aging Scheduling
The bi-directional linkage between the power grid and electric vehicles (EVs) enables flexible, cheap and fast-responding use of vehicle batteries in the grid. However, the battery aging effects due to the additional operation cycles caused by Vehicle-to-Grid (V2G) service and the concern of the battery degradation are the main reason that keeps the customer from being the named prosumer of the grid. This paper proposes a novel active battery anti-aging V2G scheduling approach. Firstly, to evaluate the battery aging effect in V2G service, the battery degradation phenomenon is quantified by a novel use of rain-flow cycle counting (RCC) algorithm. Then, the V2G scheduling is modeled as a multi-objective optimization problem, in which the minimal battery degradation and grid load fluctuation are designed as the optimization objectives. Finally, a multi-population collaborative mechanism, which is particularly designed for the V2G scheduling problem, is also developed to improve the practicability and performance of the heuristic optimization based V2G scheduling method. The proposed methodologies are verified by numerical analysis, which highlights that the proposed V2G scheduling method can minimize battery charge/discharge cycles by optimizing the time and scale of each V2G participant while providing the same services to the grid as expected
Reproductive biology of blue marlin (Makaira nigricans) in the western Pacific Ocean
The reproductive biology
of blue marlin (Makaira nigricans)
was assessed from 1001 fish (ranging
from 121 to 275 cm in eye-to-fork
length; EFL) caught by Taiwanese
offshore longliners in the western
Pacific Ocean from September 2000
to December 2001 and from 843 gonad
samples from these fish, The overall
sex ratio of the catch was approximately
1:1 dur ing the sampling
period, but blue marlin are sexually
dimorphic; females are larger than
males. Reproductive activity (assessed
by histology), a gonadosomatic index,
and the distribution of oocyte diameters,
indicated that spawning occurred
predominantly from May to September.
The estimated sizes-at-maturity
(EFL50) were 179.76 ±1.01 cm (mean
±standard error) for females and 130
±1 cm EFL for males. Blue marlin are
multiple spawners and oocytes develop
asynchronously. The proportion of
mature females with ovaries containing
postovulatory follicles (0.41) and
hydrated oocytes (0.34) indicated that
the blue marlin spawned once every
2–3 days on average. Batch fecundity
(BF) for 26 females with the
most advanced oocytes (≥1000 μm),
but without postovulatory follicles,
ranged from 2.11 to 13.50 million
eggs (6.94 ± 0.54 million eggs). The
relationships between batch fecundity
(BF, in millions of eggs) and
EFL and round weight (RW, kg) were
BF = 3.29 × 10 –12 EFL5.31 (r2 = 0.70)
and BF = 1.59 × 10–3 RW 1.73 (r2= 0.67),
respectively. The parameters estimated
in this study are key information
for stock assessments of blue
marlin in the western Pacific Ocean
and will contribute to the conservation
and sustainable yield o
Highly Sensitive Wavelength-scale Amorphous Hybrid Plasmonic Detectors
Hybrid integration of plasmonics and Si photonics is a promising architecture
for global microprocessor interconnects. To this end, practical plasmonic
devices not only should provide athermal, broadband operation over
wavelength-scale footprint, but also support non-intrusive integration with
low-loss Si waveguides as well as CMOS back-end-of-line processes. Here, we
demonstrate a hybrid plasmonic photodetector with a single active junction
fabricated via back-end deposited amorphous materials coupled to Si nanowires
with only 1.5dB loss. Utilizing internal photoemission, our detectors measured
sensitivity of -35dBm in a 620nm by 5{\mu}m footprint at 7V bias. Moreover,
responsivity up to 0.4mA/W and dark current down to 0.2nA were obtained. The
high process tolerance is demonstrated between {\lambda}=1.2-1.8{\mu}m and up
to 100{\deg}C. The results suggest the potential towards plasmonic-photonic
optoelectronic integration on top of Si chips without costly process
modifications.Comment: 4 pages, 4 figure
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