54 research outputs found
Modulation instability induced by cross-phase modulation in a dual-wavelength dispersion-managed soliton fiber ring laser
We report on the observation of modulation instability induced by cross-phase
modulation in a dual-wavelength operation dispersion-managed soliton fiber ring
laser with net negative cavity dispersion. The passively mode-locked operation
is achieved by using nonlinear polarization rotation technique. A new type of
dual-wavelength operation, where one is femtosecond pulse and the other is
picosecond pulse operation, is obtained by properly rotating the polarization
controllers. When the dual-wavelength pulses are simultaneously circulating in
the laser ring cavity, a series of stable modulation sidebands appears in the
picosecond pulse spectrum at longer wavelength with lower peak power due to
modulation instability induced by cross-phase modulation between the two lasing
wavelengths. Moreover, the intensities and wavelength shifts of the modulation
sidebands can be tuned by varying the power of the femtosecond pulse or the
lasing central wavelengths of the dual-wavelength pulses. The theoretical
analysis of the modulation instability induced by cross-phase modulation in our
fiber laser is also presented.Comment: 26 pages, 10 figure
Hybrid SRRs design and fabrication for broadband terahertz metamaterials
10.1109/JPHOT.2012.2207711IEEE Photonics Journal451267-127
Tunable resonance enhancement of multi-layer terahertz metamaterials fabricated by parallel laser micro-lens array lithography on flexible substrates
10.1364/OME.1.000151Optical Materials Express12151-15
Ceramide accumulation and up-regulation of proinflammatory interleukin-1 beta exemplify lipotoxicity to mediate declines of reproductive efficacy of broiler hens
The study was conducted to delineate fundamental mechanisms that initiate the deleterious effect of fuel overloading on reproductive efficacy of broiler breeder hens. Sixty hens at age 26 wk were fed recommended amounts of feed (160 g/d per hen) or allowed voluntary feeding (approximately 30% more than restriction). At age 35 and 50 wk, hens were sampled for further analyzes. Voluntary feeding resulted in poor egg production, high rate of mortality, and abnormal ovarian structure (mainly overt hierarchical follicle atresia at age 35 wk and ovarian involution at age 50 wk). In contrast to feed-restricted hens, voluntary feeding also induced metabolic dysregulations that comprised enhanced adiposity; hepatic triacylglycerol accumulation; and elevated concentrations of plasma glucose, NEFAs, very low density lipoprotein, triacylglycerol, phospholipids, and sphingomyelin (P < 0.05). Furthermore, hepatic and circulating ceramide and sphingomyelin accumulation, and up-regulation of proinflammatory IL-1 beta expression in liver and adipose tissues (P < 0.05) systemically manifested the development of lipotoxicity in feed-satiated hens. Lipotoxicity leading to impaired ovarian dysfunctions, including follicle atresia, ovarian regression, and a decline of circulating estradiol levels (P < 0.05) in feed-satiated hens, was further exemplified by ceramide accumulation and up-regulation of IL-1 beta, serine palmitoyltransferase, and sphingomyelinase transcript abundance, but suppressed protein kinase Akt activation (P < 0.1 to 0.05) within the hierarchical follicles. This study provides the first in vivo evidence of the actions of ceramide and IL-1 beta in mediating overfeeding-induced follicle atresia and progression of ovarian involution in broiler hens. (C) 2012 Elsevier Inc. All rights reserved
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