Fluctuation of Global Gene Expression by Endogenous miRNA Response to the Introduction of an Exogenous miRNA

Most of the intracellular endogenous microRNAs (endo-miRNAs) are considered to be saturated in Argonaute (Ago) proteins in the RNA-induced silencing complexes (RISCs). When exogenous miRNAs (exo-miRNAs) are introduced into cells, endo-miRNAs in the RISC may be replaced with exo-miRNAs or exo-miRNAs, and endo-miRNAs might also compete for the position in the newly synthesized RISC with each other. This would lead to the fluctuation of global gene expression not only by repression of exo-miRNA target gene expression, but also by the increase of the endo-miRNA target gene expression. In the present study, we quantified the changes in the expression levels of target genes of exo-miRNA and endo-miRNA in the cells transfected with fifteen different exo-miRNAs by microarray experiments. Different exo-miRNAs increased ratios of expression levels of target genes of a given endo-miRNA to different extents, suggesting that the replacement efficiencies might differ according to the exo-miRNA types. However, the increased ratios in the expression levels of each endo-miRNA target genes by the transfection of any particular exo-miRNA were mostly equivalent, suggesting that the endo-miRNAs present in the RISC might be replaced with excessive exo-miRNAs at similar levels, probably because they exist in single-stranded forms in the RISC.     

A super-dynamic flip-flop circuit for broad-band applications up to24 Gb/s utilizing production-level 0.2-μm GaAs MESFETs

This paper describes a novel dynamic flip-flop (FF) circuit that can operate 30% faster than conventional clocked inverter-type FFs. A new wideband clock buffer is introduced to cover the FF operation range. An 8- to 24-Gb/s decision circuit and a 9- to 26-GHz 1/2 frequency divider were developed utilizing production-level 0.2-μm GaAs MESFET technology     

Two-dimensionally quantized friction observed with two-dimensional frictional force microscope

Using a two-dimensional frictional force microscope, we studied the two-dimensional nature of the atomic scale friction between a Si₃N₄ sharp tip and a cleaved graphite surface, which is composed of only C atoms and is a good conductor. As a result, we observed the two-dimensionally quantized friction with the lattice periodicity of the graphite surface, similarly to mica, MoS₂ and NaF surfaces. Thus quantized friction occurs at material surfaces which are composed of not only some elements but also of a single element, and the quantized friction does not depend on the conductivity of the surface.     

NRZ operation at 40 Gb/s of a compact module containing an MQW electroabsorption modulator integrated with a DFB laser

NRZ operation at 40 Gb/s has been successfully performed using a very compact module of a multiple-quantum-well (MQW) electroabsorption modulator integrated with a distributed-feedback (DFB) laser. While the DFB laser is injected with a constant current, the integrated MQW electroabsorption modulator is driven with a 10-Gb/s electrical NRZ signal. A clearly opened eye diagram has been observed in the modulated light from the modulator. And a receiver sensitivity of -27.2 dBm at 10/sup -9/ has been experimentally confirmed in the bit-error-rate (BER) performance.     

Analysis and application of a novel model for estimating powerdissipation of optical interconnections as a function of transmissionbit error rate

This paper proposes a novel model for estimating power dissipation of optical/electrical interconnections as a function of transmission bit error rate. This model is applied to a simplified optoelectronic transmitter and receiver configuration in which a photodetector is directly connected to the decision circuit. It is analytically verified that this configuration can achieve error-free operation with low power under practical operating conditions. A comparison between optical and electrical interconnections based on this simplified configuration is performed. This result shows the interconnection length and bit rate at which optical interconnection is superior in terms of power dissipation to electrical interconnection, Only optical interconnections achieve error-free operation with 40 mW power dissipation at a transmission bit rate of 10 Gb/s and an interconnection length over 7 m     

An 80-Gb/s optoelectronic delayed flip-flop IC using resonanttunneling diodes and uni-traveling-carrier photodiode

This paper describes an 80-Gb/s optoelectronic delayed flip-flop (D-FF) IC that uses resonant tunneling diodes (RTDs) and a uni-traveling-carrier photodiode (UTC-PD). A circuit design that considers the AC currents passing through RTDs and UTC-PD is key to boosting circuit operation speed. A monolithically fabricated IC operated at 80 Gb/s with a low power dissipation of 7.68 mW. The operation speed of 80 Gb/s is the highest among all reported flip-flops. To clarify the maximum operation speed, we analyze the factors limiting circuit speed. Although the bandwidth of UTC-PD limits the maximum speed of operation to 80 Gb/s at present, the circuit has the potential to offer 100-Gb/s-class operation     

Seasonal development of Leptotrombidium akamushi (Acari: Trombiculidae) under field temperatures

Engorged larvae of Leptotrombidium akamushi (Brumpt), a vector of scrub typhus, were reared in small plastic containers placed on the ground and fed fresh eggs of the collembolan Sinella curviseta Brook. Engorged larvae obtained in October developed into deutonymphs through protonymphs approximately 1 mo before winter and became dormant in the cold winter season (approximately 3 mo). Most deutonymphs developed into tritonymphs in April and adults in May. Females began laying eggs in mid-June and the numbers of unfed larvae showed a peak in August. The mites reared from July rapidly developed into adults by August, and laid eggs in September. Larvae were most abundant in October, and adults became dormant in the winter. The same adults laid eggs from early May to late June and, upon hatching, the larval population peaked in early July of the 2nd summer. Most larvae died before the 2nd winter. Eggs hatched approximately 3 wk after oviposition and longevity of unfed larvae was 2 mo. Because of this very short incubation period, L. akamushi larvae occur in the summer, whereas L. pallidum Nagayo, Miyagawa, Mitamura & Tamiya, and L. scutellare Nagayo, Miyagawa, Mitamura, Tamiya & Tenjin occur in the autumn, although 3 species lay eggs from May to August.     

High-speed and low-power operation of a resonant tunneling logicgate MOBILE

High-speed operations up to 35 Gb/s were demonstrated for a resonant tunneling (RT) logic gate monostable-bistable transition logic element (MOBILE). The test circuit consisted of a MOBILE and a DCFL-type output buffer, and it was fabricated using InP-based resonant tunneling diode/HEMT integration technology. This operation bit rate is close to the cutoff frequency of the 0.7-μm gate HEMTs used in the circuit, and was obtained after improvement of the output buffer design. This result indicates the high-speed potential of the MOBILE, though the speed is still limited by the buffer. The power dissipation of the MOBILE was also discussed based on a simple equivalent circuit model of RTDs. This revealed that the power dissipation is as small as 2 mW/gate over a wide range of operation bit rates