2,379 research outputs found
Dynamic asset allocation with ambiguous return predictability
We study an investor's optimal consumption and portfolio choice problem when he is confronted with two possibly misspecified submodels of stock returns: one with IID returns and the other with predictability. We adopt a generalized recursive ambiguity model to accommodate the investor's aversion to model uncertainty. The investor deals with specification doubts by slanting his beliefs about submodels of returns pessimistically, causing his investment strategy to be more conservative than the Bayesian strategy. Unlike in the Bayesian framework, the hedging demand against model uncertainty may cause the investor's stock allocation to decrease sharply given a small doubt of return predictability, even though the expected return according to the VAR model is large. Over much of the parameter space, the robust strategy is very close to the Bayesian strategy with Epstein-Zin preferences and risk aversion chosen to match the same average portfolio holdings. This is true in particular when the IID model is unlikely and the dividend yield is low, as in recent years. However, differences in strategies can be substantial if the IID model is unlikely and the dividend yield is high
40-Gbps vestigial sideband half-cycle Nyquist subcarrier modulation transmission experiment and its comparison with orthogonal frequency division multiplexing
This is the published version. Copyright 2014 Society of Photo-optical Instrumentation EngineersWe experimentally demonstrate the superior performance of a 40-Gbps 16-QAM half-cycle Nyquist subcarrier modulation (SCM) transmission over a 100-km uncompensated standard single-mode fiber using dual-drive Mach-Zehnder modulator-based vestigial sideband intensity modulation and direct detection. The impact of modulator chirp on the system performance is experimentally evaluated. This Nyquist-SCM technique is compared with optical orthogonal frequency division multiplexing in both back-to-back and 100-km transmission experiments, and the results show that the Nyquist system has a better performance
Iterative intersymbol interference cancellation in vestigial sideband Nyquist–subcarrier modulation system
This is the published version. © 2014 Society of Photo-Optical Instrumentation Engineers
(SPIE)The intersymbol interference caused by dispersion, chirp, and a vestigial sideband filter in intensity
modulation and a direct detection single carrier system is analyzed theoretically and numerically. An iterative
nonlinear intersymbol interference cancellation technique is proposed and experimentally demonstrated in a 40-
Gbps 16-QAM Mach-Zehnder modulator-based vestigial sideband intensity modulation and direct detection halfcycle
Nyquist–subcarrier modulation system over a 100-km uncompensated standard single-mode fiber transmission
for the first time. The experimental results show that 2.2-dB receiver sensitivity improvement is obtained
at the forward error correction limit by using the iterative technique
IMMEDIATE EFFECTS OF WARM UP BY OVERWEIGHED BAT IMPLEMENT ON BAT SWING VELOCITY
The purpose of this study was to investigate the immediate effects of warming up by overweighed bat implement on bat swing velocity. Five softball players worked in this experiment and processed the following steps: swing official bat with and without overweight warm-ups (5 and 10 times). The maximal velocity of official bat swing was recorded by a 3-D cinematograph. By one-way ANOVA, the results were described as follows: the maximal velocity of official bat swing after 5-swingings of the overweight bat was greater than that without warm up (F=9.28,
Further understanding the nature of within a chiral quark model
In our previous works, we have analyzed the two-body strong decays of the
low-lying baryon states within a chiral quark model. The results show
that the resonance favors the three-quark state with
classified in the quark model. With this assignment, in the present work we
further study the three-body strong decay and coupled-channel effects on from nearby
channels , and within the chiral
quark model as well. It is found that the resonance has a
sizeable decay rate into the three-body final state . The
predicted ratio is close to the up limit measured by the Belle
Collaboration in 2019, however, our predicted ratio is too small to be
comparable with the recent data . Furthermore, our results show
that the coupled-channel effects on the is not large, its
components should be dominated by the bare three-quark state, while the
proportion of the molecular components is only . To clarify the
nature of , the ratio is
expected to be tested by other experiments.Comment: 7 pages, 3 figure
AMPK-α1 functions downstream of oxidative stress to mediate neuronal atrophy in Huntington's disease
AbstractHuntington's disease (HD) is an autosomal dominant neurological disorder that is induced by a CAG trinucleotide expansion in exon 1 of the Huntingtin (HTT) gene. We previously reported that the abnormal activation of an important energy sensor, AMP-activated protein kinase α1 (AMPK-α1), occurs in the brains of mice and patients with HD, which suggests that this abnormal activation may contribute to neuronal degeneration in HD. In the present study, we demonstrated that the elevated oxidative stress that was evoked by a polyQ-expanded mutant HTT (mHTT) caused the abnormal activation of AMPK-α1 and, subsequently, resulted in neurotoxicity in a striatal progenitor cell line (STHdhQ109) and in the striatum of a transgenic mouse model of HD (R6/2). The systematic administration of an antioxidant (N-acetyl-cysteine, NAC) to R6/2 mice suppressed the activation of AMPK-α1, reduced neuronal toxicity, which was assessed by the activation of caspases, increased neuronal density, ameliorated ventricle enlargement, and improved motor dysfunction. This beneficial effect of NAC in vivo appears to be direct because NAC also reduced the activation of AMPK-α1 and the death of STHdhQ109 cells upon elevated oxidative stress. Moreover, the activation of AMPK enhanced the level of oxidative stress in STHdhQ109 cells, in primary neurons of R6/2 mice, and in the striatum of two different HD mouse models (R6/2 and Hdh150Q/+), whereas the inhibition of AMPK reduced the level of oxidative stress. Collectively, our findings suggest that positive feedback regulation between the elevated oxidative stress and the activation of AMPK-α1 contributes to the progression of HD
Current Reversals in a inhomogeneous system with asymmetric unbiased fluctuations
We present a study of transport of a Brownian particle moving in periodic
symmetric potential in the presence of asymmetric unbiased fluctuations. The
particle is considered to move in a medium with periodic space dependent
friction. By tuning the parameters of the system, the direction of current
exhibit reversals, both as a function of temperature as well as the amplitude
of rocking force. We found that the mutual interplay between the opposite
driving factors is the necessary term for current reversals.Comment: 9 pages, 7 figure
- …