A Fermi-level managed barrier (FMB) diode was used for the heterodyne detection of terahertz waves for the first time. A quasi-optical module integrating an FMB diode and a broadband trans-impedance ...amplifier exhibited an intermediate frequency bandwidth of 11 GHz. A very low noise-equivalent-power of 1.1 × 10−18 W/Hz was achieved at ∼300 GHz with a very low local oscillator power of 6 × 10−6 W.
This paper addresses the problem of establishing stability of nonlinear interconnected systems. This paper introduces a mathematical formulation of the state-dependent scaling problems whose ...solutions directly provide Lyapunov functions proving stability properties of interconnected dissipative systems in a unified manner. Stability criteria are interpreted as sufficient conditions for the existence of solutions to the state-dependent scaling problems. Computing solutions to the problems is straightforward for systems covered by classical stability criteria. It, however, could be too difficult for systems with strong nonlinearity. The main purpose of this paper is to demonstrate the effectiveness beyond formal applicability by focusing on interconnected integral input-to-state stable (iISS) systems and input-to-state stable (ISS) systems. This paper derives small-gain-type theorems for interconnected systems involving iISS systems from the state-dependent scaling formulation. This paper provides solutions and Lyapunov functions explicitly. The new framework seamlessly generalizes the ISS small-gain theorem and classical stability criteria such as the L p small-gain theorem, the passivity theorems, the circle, and Popov criteria. State-dependence of the scaling is crucial for effective treatment of essential nonlinearities, while constants are sufficient for classical nonlinearities
An anti-parallel (AP) diode pair based on a Fermi-level managed barrier (FMB) diode was developed for the sub-harmonic mixing of terahertz waves. A quasi-optical module integrating an AP–FMB diode ...pair and a trans-impedance amplifier exhibited a very low noise-equivalent-power of 9 × 10−19 W/Hz at an input signal frequency of 304 GHz with a very low local oscillator power of 30 μW.
A zero-biased Fermi-level managed barrier diode that was packaged with a WR-3 rectangular-waveguide-input port was developed. For direct (square-law) detection operations, the fabricated module ...exhibited a 3 dB bandwidth covering the whole WR-3 band. The intermediate frequency bandwidth in heterodyne detection was, therefore, dominated by the bandwidth of the integrated preamplifier, and it was measured to be about 40 GHz. The minimum noise-equivalent power obtained was as low as 7 × 10−18 W/Hz at around 300 GHz even with a very low local oscillator power of 30 μW.
Phosphatidylinositol-3-kinase (PI3K) is a lipid kinase and generates phosphatidylinositol-3,4,5-trisphosphate (PI(3, 4, 5)P3). PI(3, 4, 5)P3 is a second messenger essential for the translocation of ...Akt to the plasma membrane where it is phosphorylated and activated by phosphoinositide-dependent kinase (PDK) 1 and PDK2. Activation of Akt plays a pivotal role in fundamental cellular functions such as cell proliferation and survival by phosphorylating a variety of substrates. In recent years, it has been reported that alterations to the PI3K-Akt signaling pathway are frequent in human cancer. Constitutive activation of the PI3K-Akt pathway occurs due to amplification of the PIK3C gene encoding PI3K or the Akt gene, or as a result of mutations in components of the pathway, for example PTEN (phosphatase and tensin homologue deleted on chromosome 10), which inhibit the activation of Akt. Several small molecules designed to specifically target PI3K-Akt have been developed, and induced cell cycle arrest or apoptosis in human cancer cells in vitro and in vivo . Moreover, the combination of an inhibitor with various cytotoxic agents enhances the anti-tumor efficacy. Therefore, specific inhibition of the activation of Akt may be a valid approach to treating human malignancies and overcoming the resistance of cancer cells to radiation or chemotherapy.
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