Impacts of filter-feeding fishes on the long-term changes of crustacean zooplankton in a eutrophic subtropical Chinese lake

Long-term changes In the crustacean zooplankton community (calanoid and cyclopoid copepods and cladocerans) were studied in Lake Donghu, a shallow and eutrophic Chinese lake. This lake had been earlier stocked with two pump Alter-feeding Ashes, silver carp (Hypopthalmichthys molitrix) and bighead carp (Aristichthys nobilis). During the 1950s and the mid-1980s, the ratio of copepods to cladocerans was relatively stable but showed a general increase thereafter. From the early-1980s to the 1990s, calanoid/cyclopoid ratios decreased obviously. In the 1990s, Cyclops vicinus, Diaphanosoma brachyurum, and Moina micrura were dominant the abundance of C. vicinus and M. micrura increased significantly; and D, brachyurum showed a substantial decrease. The study shows that under extremely high pressure of Ash predation, the species which could recover rapidly from fish predation would be the most likely to survive and increase their numbers.

Long-term changes of Copepoda community (1957-1996) in a subtropical Chinese lake stocked densely with planktivorous filter-feeding silver and bighead carp

In contrast to the relatively well documented impact of particulate-feeding fish on zooplankton communities, little attention has been devoted to the impact of filter-feeding fish. Filter-feeding silver and bighead carp are the most intensively cultured fish species in Asia and comprise much of the production of Chinese aquaculture. However, little information is known about the impact of either fish on the zooplankton community. Long-term changes in the Copepoda community (1957-1996) were studied at two sampling stations of a subtropical Chinese lake (Lake Donghu) dominated by silver and bighead carp. For both calanoids and cyclopoids, the littoral station (I) was much more resource profitable than the pelagic station (II). There has been a tremendous increase in the annual fish catch over the past 30 years due to the increased stocking with fingerlings of the two carp species. There was a notably higher fish density at Station I than at Station II. Cyclopoid abundance was notably higher at Station I than at Station II during the 1950s to the 1980s, while the reverse became true in the 1990s. This is probably because when fish abundance increased to an extremely high level, the impact of fish predation on the cyclopoids became more important than that of food resources at the littoral station. At both stations, cyclopoid abundance was relatively low in spite of the presence of abundant prey. Similarly, calanoid density did not differ significantly between the two stations in the 1950s and 1960s, but was significantly lower at Station I than at Station II during the 1980s and 1990s. Such changes are attributed to the gradient of fish predation between the stations and an increasing predation pressure by the fish. The increased fish predation also correlated with a shift in summer-dominant calanoids from larger species to smaller ones. In conclusion, the predaceous cyclopoids are affected by fish predation to a much lesser extent than the herbivorous calanoids, and therefore increased predation by filter-feeding fish results in a definite increase in the cyclopoid/calanoid ratio. Predation by filter-feeding fish has been a driving force in shaping the copepod community structure of Lake Donghu during the past decades.

Changes in the plankton community following introduction of filter-feeding planktivorous fish

1. We conducted enclosure experiments in a shallow eutrophic lake, in which a biomass gradient of the filter-feeding planktivore, silver carp, Hypophthalmichthys molitrix Valenciennes, was created, and subsequent community changes in both zooplankton and phytoplankton were examined. 2. During a summer experiment, a bloom of Anabaena flos-aquae developed (approximate to 8000 cells mL(-1)) solely in an enclosure without silver carp. Concurrent with, or slightly preceding the Anabaena bloom, the number of rotifer species and their abundance increased from seven to twelve species (1700-14 400 organisms L-1) after the bloom in this fish-free enclosure. Protozoans and bacteria were generally insensitive to the gradient of silver carp biomass. 3. During an autumn experiment, on the other hand, large herbivorous crustaceans were more efficient than silver carp in suppressing the algae, partly because the lower water temperature (approximate to 24 degrees C) inhibited active feeding of this warm-water fish and also formation of algal colonies. Heterotrophic nanoflagellate and bacterial densities were also influenced negatively by the crustaceans. 4. Correspondence analysis (CA) was applied to the weekly community data of zooplankton and phytoplankton. A major effect detected in the zooplankton community was the presence/absence of silver carp rather than the biomass of silver carp, whereas that in the phytoplankton community was the fish biomass before the Anabaena bloom, but shifted to the presence/absence of the fish after the bloom.

DISCRETELY TUNABLE FIBER RING LASER USING FBG TUNABLE FILTER AND MACH-ZEHNDER INTERFEROMETER

A discretely tunable Er-doped fiber-ring laser using a fiber Mach-Zehnder interferometer (MZI) and a tunable fiber Bragg grating (FBG) is proposed. In this scheme, the combination of MZI and FBG acts as a discrete wavelength selector. Analysis of its transmission function shows that discrete wavelength tuning can be realized, and experiments demonstrate 64 single-mode outputs with a mode spacing of 181.7 pm, and the output power is quite stable in the whole tuning range. (C) 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51 2595-2598, 2009; Published online in Wiley InterScience (www. interscience.wiley.com). DOI 10.1002/mop.24690

Resonant Enhanced Wave Filter and Waveguide via Surface Plasmons

The authors present an analysis of plasmonic wave filter and curved waveguide, simulated using a 2-D finite-difference time-domain technique. With different dielectric materials or surface structures located on the interface of the metal/dielectric, the resonant enhanced wave filter can divide light waves of different wavelengths and guide them with low losses. And the straight or curved waveguide can confine and guide light waves in a subwavelength scale. Within the 20 mu m simulation region, it is found that the intensity of the guided light at the interface is roughly four times the peak intensity of the incident light.

Novel triplexing-filter design using silica-based direction coupler and an arrayed waveguide grating

A new triplexing filter based on a silica direction coupler and an arrayed waveguide grating is presented. Using a combination of a direction coupler and an arrayed waveguide grating, a 1310-nm channel is multiplexed and 1490- and 1550-nm channels are demultiplexed for fiber-to-the-home. The direction coupler is used to coarsely separate the 1310-nm channel from the 1490- and 1550-nm channels. Subsequently, an arrayed waveguide grating is used to demultiplex the 1490- from 1550-nm channel. The simulated spectra show the 1-dB bandwidth of 110 nm for the 1310-nm channel and 20 and 20.5 nm for the 1490- and 1550-nm channels. The insertion loss is only 0.15 dB for 1310 nm and 5 dB for 1490 and 1550 nm. The crosstalk between the 1490- and 1550-nm channels was less than -35 dB. (C) 2009 Society of Photo-Optical Instrumentation Engineers. [DOI 10.1117/1.3065508]

Design and Fabrication of a Photonic Crystal Channel Drop Filter Based on an Asymmetric Silicon-on-Insulator Slab

We report on the design and fabrication of a photonic crystal (PC) channel drop filter based on an asymmetric silicon-on-insulator (SOI) slab. The filter is composed of two symmetric stick-shape micro-cavities between two single-line-defect (W1) waveguides in a triangular lattice, and the phase matching condition for the filter to improve the drop efficiency is satisfied by modifying the positions and radii of the air holes around the micro-cavities. A sample is then fabricated by using electron beam lithography (EBL) and inductively coupled plasma (ICP) etching processes. The measured 0 factor of the filter is about 1140, and the drop efficiency is estimated to be 73% +/- 5% by fitting the transmission spectrum.

A Si-based tunable narrow-band flat-top filter with multiple-step-type Fabry-Perot cavity structure

In the optical network, the quick and accurate alignment with wavelength is an important issue during the channel detection. At this point, a filter having flat-top response characteristic is an effective solution. Based on multiple-step-type Fabry-Perot cavity structure, a novel all-Si-based thermooptical tunable flat-top filter with narrow-band has been fabricated, using our patent silicon-on-reflector bonding technology. The device demonstrated a 1-dB flat-top width of 1 nm, 3-dB band of 3 nm, free spectra range of 8 nm, and the tuning range of 4.6 nm was obtained under the applied voltage of 4 V.

Thermally tunable optical filter with crystalline silicon as cavity

A novel method to fabricate a thermally tunable filter with a tuning range of 26 nm from 1.504 to 1.530 mum is reported. The high-reffectivity bottom mirror is deposited in the hole formed by anisotropically etching in the basic solution from the backside of the slice with the buried SiO2 layer in silicon-on-insulator substrate as the etching-stop layer. Because of the formation of the mesa and the removing of the substrate of the hole, the power from the metal heater can be more effectively consumed in the crystalline silicon cavity. So it lowers the power consumption and the filter has a higher tuning range. (C) 2004 Elsevier B.V. All rights reserved.

Color filter-less technology of LED back light for LCD-TV - art. no. 68410G

Back Light Unit (BLU) and Color Filter are the two key components for the perfect color display of Liquid Crystal Display (LCD) device. LCD can not light actively itself, so a form of illumination, Back Light Unit is needed for its display. The color filter which consists of RGB primary colors, is used to generate three basic colors for LCD display. Traditional CCFL back light source has several disadvantages, while LED back light technology makes LCD obtain quite higher display quality than the CCFL back light. LCD device based on LED back light owns promoted efficiency of display. Moreover it can generate color gamut above 100% of the NTSC specification. Especially, we put forward an idea of Color Filter-Less technology that we design a film which is patterned of red and green emitting phosphors, then make it be excited by a blue light LED panel we fabricate, for its special emitting mechanism, this film can emit RGB basic color, therefore replace the color filter of LCD device. This frame typically benefits for lighting uniformity and provide pretty high light utilization ratio. Also simplifies back light structure thus cut down the expenses.

Ultra-compact silicon-on-insulator optical filter based on sidewall Bragg grating

Micro-cavity structure composed of silicon wire with 240nm square cross section and two symmetrical sidewall waveguide Bragg gratings is fabricated and studied for the operation under telecommunication wavelengths. Optical filter of quasi-TE mode was realized based on this cavity. In such micro-cavity, optical quality factor (Q) was measured up to 380 with a 4.8nm free spectral range (FSR) and 12dB fringe contrast (FC). The measured group index of silicon waveguide with only 240nm square cross section was between 3.80 and 5.43. It is the first time group delay of silicon wire waveguide with such small core dimension is studied. Larger group delay can be expected after optimizing the design parameters and the fabrication process.

Design of Low Power Multi-Standard Active-RC Filter for WLAN and DVB-H

In this paper, a low-power, highly linear, integrated, active-RC filter exhibiting a multi-standard (IEEE 802.11a/b/g and DVB-H) application and bandwidth (3MHz, 4MHz, 9.5MHz) is present. The filter exploits digitally-controlled polysilicon resister banks and an accurate automatic tuning scheme to account for process and temperature variations. The automatic frequency calibration scheme provides better than 3% corner frequency accuracy. The Butterworth filter is design for receiver (WLAN and DVB-H mode) and transmitter (WLAN mode). The filter dissipation is 3.4 mA in RX mode and 2.3 mA (only for one path) in TX mode from 2.85-V supply. The dissipation of calibration consumes 2mA. The circuit has been fabricated in a 0.35um 47-GHz SiGe BiCMOS technology, the receiver and transmitter occupy 0.28-mm(2) and 0.16-mm(2) (calibration circuit excluded), respectively.

Simulation and fabrication of the SiC-based clamped-clamped filter

In this paper, the SiC-based clamped-clamped filter was designed and fabricated. The filter was composed of two clamped-clamped beam micromechanical resonators coupled by a spring coupling beam. Structural geometries, including the length and width of the resonator beam and coupling beam, were optimized by simulation for high frequency and high Q, under the material properties of SiC. The vibrating modes for the designed filter structure were analyzed by finite element analysis (FEA) method. For the optimized structure, the geometries of resonator beams and coupling beams, as well as the coupling position, the SiC-based clamped-clamped filter was fabricated by surface micromaching technology.

Design and Fabrication of a Photonic Crystal Channel Drop Filter Based on an Asymmetric Silicon-on-Insulator Slab

We report on the design and fabrication of a photonic crystal (PC) channel drop filter based on an asymmetric silicon-on-insulator (SOI) slab. The filter is composed of two symmetric stick-shape micro-cavities between two single-line-defect (W1) waveguides in a triangular lattice, and the phase matching condition for the filter to improve the drop efficiency is satisfied by modifying the positions and radii of the air holes around the micro-cavities. A sample is then fabricated by using electron beam lithography (EBL) and inductively coupled plasma (ICP) etching processes. The measured 0 factor of the filter is about 1140, and the drop efficiency is estimated to be 73% +/- 5% by fitting the transmission spectrum.

High-Q and High-extinction-ratio Microdisk Add-drop Filter with Grating Couplers in Silicon-on-Insulator

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