Existence and stability of periodic solutions for a delayed prey–predator model with diffusion effects

Existence and stability of spatially periodic solutions for a delay prey-predator diffusion system are concerned in this work. We obtain that the system can generate the spatially nonhomogeneous periodic solutions when the diffusive rates are suitably small. This result demonstrates that the diffusion plays an important role on deriving the complex spatiotemporal dynamics. Meanwhile, the stability of the spatially periodic solutions is also studied. Finally, in order to verify our theoretical results, some numerical simulations are also included

Paper Session II-C - High-Resolution Integrated Micro Gyroscope for Space Applications

In this paper, an integrated capacitive gyroscope fabricated by CMOS-MEMS technology is presented. The CMOS-compatibility of the fabrication process enables full integration of the sensor with interface and signal conditioning circuitry on a single chip. The entire microstructure is single-crystal silicon based, resulting in large proof mass and good mechanical behaviors. Thus, high-resolution and high-robustness microgyroscopes can be obtained. With a resolution of about 0.01°/s/Hz112 , the fabricated gyroscope chip is only as small as 1.5mm by 2mm including the sensing elements and integrated electronics. The robustness, light weight and high performance make this type of MEMS gyroscope very suitable for space navigation applications where payload is critical. The on-chip capacitive sensing circuitry employs chopper stabilization technique to minimize the influence of 1/f noise. The on-chip circuits also include a two-stage fully differential amplifier and a DC feedback loop to cancel the DC offset. The CMOS fabrication was performed through MOSIS by using the 4-metal TSMC 0.35 μm CMOS process. The post-CMOS micromachining processing consists of only dry etch steps and uses the interconnect metal layers as etching masks. Single-crystal silicon (SCS) structures are produced by applying a backside etch and forming a 60μm-thick SCS membrane. This work is sponsored by NASA through the UCF/UF Space Research Initiative

Monitoring resistance of Plasmdium vivax: Point mutations in dihydrofolate reductase gene in isolates from Central China

<p>Abstract</p> <p>Background</p> <p>Malaria still represents a significant public health problem in China, and the cases dramatically increased in Central China after 2001. Antifolate resistance in <it>Plasmodium vivax </it>is caused by point mutations in genes encoding dihydrofolate reductase (<it>pvdhfr</it>) and dihydropteroate synthase (<it>pvdhps</it>). In this study, we used direct sequencing to investigate genetic variation in <it>pvdhfr </it>of malaria patients' samples from Central China.</p> <p>Results</p> <p>Among all the samples, 21.4% were wild-type, whereas mutations were detected at three codons (58, 61 and 117) including single mutant (34.6%) and double mutants (43.8%). The most prevalent mutant allele was the one with double mutation at codons 58 and 117 (24.6%). Three types of single mutation (S58R, T61M and S117N) were found in 2.1%, 11.8% and 20.9% of parasite isolates, respectively. The four <it>P. vivax </it>parasite populations in Central China also differed in <it>pvdhfr </it>allele frequencies.</p> <p>Conclusions</p> <p>This study suggested that <it>P. vivax </it>in Central China may be relatively susceptible to pyrimethamine. And it also highlights genotyping in the <it>pvdhfr </it>genes remains a useful tool to monitor the emergence and spread of <it>P. vivax </it>pyrimethamine resistance.</p