Increasing the lifetime of wireless sensors is essential for the proliferation of wireless sensor networks in various environments. In this paper, the relationship between bandwidth and energy ...consumption is exploited to increase the lifetime of the sensors. A variable bandwidth allocation scheme that uses time-frequency slot assignment is proposed to reduce the energy consumption of a collaborative sensor network which has large spatial variation in node density and event rates. To assign the time-frequency slots to the sensor network, a novel algorithm is presented, which results in significant energy savings over the conventional constant bandwidth allocation scheme.
In this paper, a variation tolerant reconfigurable time difference amplifier (TDA) is presented. The proposed time difference amplifier removes delay lines used in conventional calibration loop which ...are the most critical bottle-neck for achieving higher gain. A gated mutual exclusive (GMUTEX) circuit and a NAND based ring oscillator enable reconfigurable gain corresponding to an input code word. In addition, a time difference pre-amplifier is employed in phase frequency detector (PFD) of delay locked loop (DLL) to reduce its input phase offset. The proposed TDA is implemented and simulated in 90 nm CMOS, which shows 4 to 128 of reconfigurable gain within 6.3% of absolute gain error and 2.5% fluctuation under PVT variable condition.
A time-based successive approximation register (SAR) analog to digital converter (ADC) using a pulse width modulation is presented for scaled CMOS technologies. A binary search in the proposed ADC ...performs on time-domain signal processing using a pulse width modulation with a single capacitor. Since the ADC employs time-domain signal processing, the proposed ADC does not suffer from a process variation such as a capacitor mismatch. The proposed ADC also has low input capacitance, since it has the single capacitor, not the capacitor array in conventional SAR ADC. A feasibility of the proposed ADC is verified by simulations using ADC models having 10 bit resolution in ideal condition as well as in non-ideal condition.
Optimal Condition for Sperm-mediated Gene Transfer by Liposome in Pigs Kim, T.S. (Kangwon National University, Chuncheon, Republic of Korea); Yang, Cao (Dalian University, Dalian, China); Lee, Y.S. (Kangwon National University, Chuncheon, Republic of Korea) ...
Reproductive & developmental biology,
06/2008, Letnik:
32, Številka:
2
Journal Article
Recenzirano
Production of transgenic animals for studying specific gene has been limited due to a low efficiency, lack of skilled researchers and the need for expensive equipment. Currently, the boar spermatozoa ...as a vector to deliver exogenous DNA into the oocyte were used to improve the efficiency of transfection rate. In this study, we revealed that the optimal conditions for DNA uptake in spermatozoa by liposome were to 90 min of incubation, 17℃, 10∨5 spermatozoa, 4 ng/ml of exogenous DNA and 0.5% (v/v) liposome, without damage to fertility. In addition, the developmental rate to the blastocyst stage of embryo in control group was significantly higher than those embryos with exogenous DNA and liposome, whereas there were no significant differences in embryo development between the liposome and type of DNA. The transfection rates of embryo using treated spermatozoa with both liposome and circular DNA were higher than those using linear DNA. These findings raise the possibility thattreated spermatozoa with liposome/DNA complexes could be used in in vitro fertilization, and the exogenous DNA transferred into the oocytes. Taken together, we demonstrated that liposome a vector for the uptake of exogenous DNA in boar spermatozoa could improve the efficiency of sperm-mediated gene transfer in creating transgenic pig and the other domestic transgenic animals.
Plasminogen Activators Activities in Oviductal Epithelial Cells during Estrus Cycle in the Pig Shin, M.Y. (Kangwon National University, Chuncheon, Republic of Korea); Kim, T.S. (Kangwon National University, Chuncheon, Republic of Korea); Kwon, E.H. (Kangwon National University, Chuncheon, Republic of Korea) ...
Reproductive & developmental biology,
06/2008, Letnik:
32, Številka:
2
Journal Article
Recenzirano
The present study was undertaken to identify changes of plasminogen activators (PAs) in porcine oviductal epithelial cells (POECs) during the estrous cycle classified with post-ovulatory stages ...(Post-Ov), early to mid-luteal stages (Early-mid L) and pre-ovulatory (Pre-Ov) stages. The urokinase-type plasminogen activator (uPA) was only observed on day 5 and day 7 of culture in the POECs on all the estrous cycles and gradually increased according to increasing culture times, but not Early-mid L. In POECs-conditioned medium, uPA, tissue-type (tPA) and tPA-PA inhibitor (tPA-PAI) activity were observed at all culture times during estrous cycles. The uPA activity of POECs-conditioned medium on Post-Ov stage were significantly (p less than 0.05) decreased during prolonged cultures. On the other hand, the tPA activity of POECs-conditioned medium at Post-Ov stage was significantly (p less than 0.05) higher on day 5 than compared to the other days. Although was higher on day 1 at Post-Ov stage, the tPA-PAI activity of POECs-conditioned medium was significantly (p less than 0.05) higher on day 7 at all stage than that of day 5 of the culture. Taken together, these results suggest that uPA, tPA and tPA-PAI are produced by POECs, and the variations of the PAs activity are regulated in the different stages of the estrous cycle.
Effects of Plasminogen on Sperm-Oocyte Interaction during In Vitro Fertilization in the Pig Sa, S.J. (University of Nottingham, Sutton Bonington Campus, Loughborough, Leicestershire, UK); Kim, T.S. (Kangwon National University, Chuncheon, Republic of Korea); Park, S.B. (National Institute of Animal Science, RDA, Seonghwan, Republic of Korea) ...
Reproductive & developmental biology,
06/2008, Letnik:
32, Številka:
2
Journal Article
Recenzirano
Plasminogen activators (PAs) are serine protease that cleave plasminogen to form the active protease plasmin. PA/plasmin system play a role in mammalian fertilization and motility and acrosome ...reaction of sperm. The present study was undertaken to identify PAs in porcine gametes and investigate a possible role of plasminogen in in vitro fertilization in the pig. When boar spermatozoa were preincubated in a fertilization medium (mTBM) for 0, 2, 4 or 6 h, the activity of tPA-PAI (110~117 kDa), tPA (62~70 kDa), and uPA (34~38 kDa) was observed in the sperm incubation medium and sperm sample. PA activities in the sperm incubation medium significantly (p less than 0.05) increased according to increasing incubation times, while PA activities in sperm significantly (p less than 0.05) decreased at the same times. In addition, the rate of acrosome reaction in spermatozoa increased by increasing culture times. When oocytes were separated from porcine cumulus-oocytes complexes at 0, 22 or 44 h of maturation culture, no PA activities were observed in cumulus free-oocyte just after aspiration from follicles. However, the activity of tPA-PAI (108~113 kDa) and tPA (75~83 kDa) was observed at 22 h of in vitro culture and significantly (p less than 0.05) increased as the duration of the culture increased. On the other hand, when porcine oocytes were activated by sperm penetration or calcium ionophore, plasminogen significantly (p less than 0.05) increased ZP dissolution time (sec) in activated oocytes by sperm penetration. These results suggest that supplementation of plasminogen to fertilization medium may play a positive role in the improvement of in vitro fertilization ability in the pig.
In this paper, a time-domain analog-to-digital converter (ADC) using time-to-digital converter (TDC) is presented. The use of TDC in ADCs is a promising technique for future scaled CMOS processes, as ...it relies on time-resolution rather than voltage resolution. In the proposed ADC, a single-slope capacitor-discharge method is employed to convert input voltage into time, which relaxes the time-domain linearity requirement of comparator. In addition, time-interleaving is employed to increase the time resolution. Lastly, a shared counter-based TDC is used for compact and simple time quantization. Simulation results in 0.25μm CMOS shows the feasibility of the proposed architecture.
In this paper, an ultra-low jitter clock generator that employs a novel automatic frequency calibration (AFC) technique is presented. To achieve low jitter, the clock generator uses an LC-VCO with ...S-bit switched tuning scheme. The clock output is taken from the output of a multi-modulus divider, which increases the output frequency range with small variation in the loop bandwidth. The capacitor array of the the VCO is controlled by a novel AFC technique that performs binary search for fast calibration and fine search to select an optimum tuning curve. A prototype chip implemented in 0.13-mum CMOS process achieves 480 MHz to 1 GHz of output frequency while consuming 22 mW from a 1.2 V supply. The measured tins jitter and calibration time of the proposed clock generator are 940 fs at 600 MM/, and 350 ns, respectively. These numbers are the fastest calibration time and one of the lowest jitter that have been reported in a clock generator.
