Two Step Timing Synchronization Scheme for OFDM Signal in General Purpose Processor Based Software Defined Radio Receiver

Software defined radio (SDR) is a technology that allows a single terminal to support various kinds of wireless systems by changing its software to reconfigure itself. A general purpose processor (GPP) based SDR receiver platform named Sora has been recently developed by Microsoft. In the GPP based SDR receiver, timing synchronization of an OFDM signal consumes a significant amount of computational resources in the GPP. In this paper, a timing synchronization scheme which uses delayed correlation and matched filtering for the GPP based SDR platform is evaluated. The two stage timing synchronization scheme reduces the computational complexity by limiting the timing range of matched filtering. The proposed scheme reduces the amount of data transmission between the memory and the GPP of the SDR platform. It is shown through an experiment that the proposed scheme reduces the number of cycles for timing synchronization by up to 30 %.     

Pipelined delay-sum architecture based on bucket-brigade devices for on-chip ultrasound beamforming

A pipelined delay-sum architecture based on bucket-brigade devices is proposed as an analog beamformer for integrated far-field steering scanning of a micromachined piezoelectric ultrasonic sensor phased array. The prototype beamformer, fabricated with an 8-/spl mu/m standard CMOS process, exhibits a total harmonic distortion of -45 dB, dynamic range of more than 65 dB, and beamforming imperfection of less than -50 dB using a 100-kHz input signal with peak voltage of 400 mV.     

MRI Study of Nucleation and Growth During the Field Induced First Order Phase Transition Between U2D2 and CNAF 3He near Absolute Zero

The field-sweep-induced first order phase transition between two nuclear antiferromagnetic states of solid ³He was studied at the temperatures near absolute zero. The phase transition proceeded in two stages. The first stage was governed by a nucleation process, in which many small seeds of the stable phase appeared in many places throughout a crystal. The measured nucleation rate was essentially temperature independent, once we corrected the data for weak temperature dependence due to limited growth of the seeds after nucleation. With the help of MRI measurements, we understand that the nucleation occurs at peculiar heterogeneous nucleation sites, which are distributed in the entire crystal. Magnetic planar defects in the nuclear ordered spin structure are proposed as a candidate for the nucleation sites. The second stage is understood as a process, which is controlled by the flow of released latent heat across the solid-liquid interface.     

Physical properties and microstructure of commercial Som-fug, a fermented fish sausage

Physical properties and the microstructure of Som-fug, a Thai-style fermented fish sausage, with seven different commercial brands were determined. The released water contents of Som-fug samples ranged from 5.81 to 15.81% and expressible water contents were different among the samples tested (p<0.05). Differences in hardness, fracturability, adhesiveness, springiness, cohesiveness and resilience were also observed. L*, a*, b* and whiteness varied with the samples. Overall, the samples had different acceptability in texture and color. Microstructural study revealed that Som-fug had a three-dimensional network. A more void and open structure correlated well with greater released water and was associated with lower hardness and cohesiveness. Therefore, the different physical properties and microstructure of Som-fug could be influenced by the differences in raw materials, ingredients, processing, and fermentation characteristics, and determined the acceptability of products.     

Heat treatment for the control of Bacillus cereus spores in foods

The effect of heat treatments on food products related to soybean curd contaminated with Bacillus cereus spores was investigated for the purpose of preventing food-poisoning outbreaks by B. cereus. In the case of B. cereus strains isolated from foods, heating foods inoculated with the spores for 20 min at 70 degrees C, 5 min at 75 degrees C, 2 min at 100 degrees C, or 10 sec with a microwave oven plus reheating after standing for 2 hr at 25 degrees C reduced the number of surviving cells within the foods to less than one-hundredth. In the case of a heat-resistant strain isolated from a food poisoning outbreak, heating for 20 min at 70 degrees C plus reheating after standing for 1.5-2 hr at 35 degrees C, heating for 10 min at 75 degrees C plus reheating after standing for 1.5-2 hr at 35 degrees C, or heating for 2 min at 100 degrees C plus reheating after standing for 4 hr at 25 degrees C was effective. There was not much difference between the flavor components in foods with and without heat treatment at 70 degrees C, as analyzed by gas chromatography-mass spectrometry. These results indicate that these heat treatments are available to control B. cereus spores, without affecting the sensory quality of the foods.     

Proposals for wastewater treatment by applying flocculating activity of cross-linked poly-gamma-glutamic acid

Cross-linked poly-gamma-glutamic acid (C-L gamma-PGA) markedly purified polluted water collected from rivers and ponds by flocculation and precipitation. This effect of C-L gamma-PGA occasionally required pretreatment with polyaluminum chloride (PAC). Components of polluted water in rivers or ponds are generally thought to be clay minerals, microorganisms and chemical compounds. In this study, the flocculating activities of C-L gamma-PGA against suspensions of bentonite, diatomaceous earth, Escherichia coli and Mycrocystis aeruginosa, and against solutions of crystal violet and bisphenol A were investigated. The mode of action of C-L gamma-PGA is thought to be based on electrostatic interaction between flocculants, C-L gamma-PGA and PAC, and the surface of polluted water components, which may lead to neutralization of the zeta-potential of those components.     

Strain selection and scale-up fermentation for FR901379 acylase production by Streptomyces sp. no. 6907

Micafungin (FK463) is a widely used treatment for life-threatening, deep-seated fungal infections. It is an echinocandin-like lipopeptide derived from the chemical modification of deacylated FR901379, a type of lipopeptide antibiotic produced by Coleophoma empetri F-11899. The palmitoyl moiety of FR901379 is deacylated by FR901379 acylase produced by Streptomyces sp. no. 6907. In this study, our goal was to generate an improved strain of Streptomyces sp. no. 6907 capable of hyperproducing the FR901379-acylase enzyme. To accomplish this goal, modified strains of Streptomyces sp. no. 6907 were generated using UV-irradiation mutagenesis, and strain selection was performed using an agar-plate screening method to efficiently select an acylase-hyperproducing strain. Three marker indices were shown to correlate with elevated acylase production: decreased candidacidal activity of FR901379, decreased proteolytic activity on skim milk, and phenotypic characteristics. Cloning and subsequent sequencing of the acylase gene from the hyperproducing mutant revealed no mutations in either the acylase structural gene or the 5'-flanking region required for gene expression. The growth medium was also modified to maximize acylase production. We successfully increased acylase activity approximately 65-fold, compared with the original growth conditions (wild strain cultured in the original unmodified medium). To minimize formation of excess foam during the fermentation process, we optimized the parameters of agitation speed, as calculated from the discharge flow rate. Using our improved strain and the optimized medium and growth conditions, we have developed an improved and highly reproducible method for stable large-scale production of FR901379-acylase.     

Acceleration of nonylphenol and 4-tert-octylphenol degradation in sediment by Phragmites australis and associated rhizosphere bacteria

We investigated biodegradation of technical nonylphenol (tNP) in Phragmites australis rhizosphere sediment by conducting degradation experiments using sediments spiked with tNP. Accelerated tNP removal was observed in P. australis rhizosphere sediment, whereas tNP persisted in unvegetated sediment without plants and in autoclaved sediment with sterile plants, suggesting that the accelerated tNP removal resulted largely from tNP biodegradation by rhizosphere bacteria. Three bacterial strains, Stenotrophomonas sp. strain IT-1 and Sphingobium spp. strains IT-4 and IT-5, isolated from the rhizosphere were capable of utilizing tNP and 4-tert-octylphenol as a sole carbon source via type II ipso-substitution. Oxygen from P. australis roots, by creating highly oxygenated conditions in the sediment, stimulated cell growth and the tNP-degrading activity of the three strains. Moreover, organic compounds from P. australis roots functioned as carbon and energy sources for two strains, IT-4 and IT-5, supporting cell growth and tNP-degrading activity. Thus, P. australis roots elevated the cell growth and tNP-degrading activity of the three bacterial strains, leading to accelerated tNP removal. These results demonstrate that rhizoremediation of tNP-contaminated sediments using P. australis can be an effective strategy.     

Enzymatic digestion of corncobs pretreated with low strength of sulfuric acid for bioethanol production

In this study, the effect and the optimum pretreatment condition of corncobs using low strength of H₂SO₄ were investigated, in which H₂SO₄ was used to improve the enzymatic digestibility of corncobs for saccharification without degradation of sugars released. The optimum pretreatment condition was found to be the addition of 0.5% (vol./vol.) H₂SO₄ and autoclaving at 122 °C for 20 min. Under this condition, the structural integrity of corncob was altered to make cellulose microfibrils more accessible for cellulase enzymes, and the enzymatic digestion of corncobs could be significantly enhanced. A high yield of sugar, 80% (wt./wt.), could be obtained at a low enzyme dosage of 0.024 g enzymes/g cobs, when pretreated. As a result, the ethanol production was obviously improved by the pretreatment, i.e., the ethanol yield of 77% (wt./wt.) was obtained within 36 h in the SSF fermentation using Saccharomyces cerevisiae NBRC2114.