An Integrated Sideband-Separating SIS Mixer Based on Waveguide Split Block for 100 GHz Band with 4.0–8.0 GHz IF

We have developed an integrated sideband-separating SIS mixer for the 100 GHz band based on the waveguide split block. The measured receiver noise temperatures with 4.0–8.0 GHz IF are less than 60 K in the LO frequency range of 90–110 GHz, and a minimum value of around 45 K is achieved at 100 GHz. The image rejection ratios are more than 10 dB in the frequency range of 90–110 GHz. We have installed the sideband-separating SIS mixer into an atmospheric ozone-measuring system at Osaka Prefecture University and successfully observed an ozone spectrum at 110 GHz in SSB mode. This experimental result indicates that the sideband-separating SIS mixer is very useful for astronomical observation as well as atmospheric observation.     

Modeling stochastic anomalies in an SIS system

We propose a stochastic SIS model to include both a Gaussian and Poissonian perturbation to account for noise and anomalies in the transmission rate. Conditions are given for stability to the disease free equilibrium and for positive Harris recurrence with a unique invariant measure for the endemic.     

The maximum number of infected individuals in SIS epidemic models: Computational techniques and quasi-stationary distributions

We study the maximum number of infected individuals observed during an epidemic for a Susceptible-Infected-Susceptible (SIS) model which corresponds to a birth-death process with an absorbing state. We develop computational schemes for the corresponding distributions in a transient regime and till absorption. Moreover, we study the distribution of the current number of infected individuals given that the maximum number during the epidemic has not exceeded a given threshold. In this sense, some quasi-stationary distributions of a related process are also discussed.     

Characterization of Nb-Based Superconducting Microstrip Lines Around the Gap Frequency

Submillimter-wave SIS (superconductor-insulator-superconductor) mixers usually adopt SIS junctions associated with an integrated tuning circuit, which tunes out the junction's geometric capacitance and is typically an inductive thin-film superconducting microstrip line. This paper mainly investigates the characteristic of Nb-based superconducting microstrip lines around the junction's gap frequency, at which the surface resistance of Nb films becomes considerable, and its effect on the performance of SIS mixers.     

一类具logistic增长率的SIS传染病模型的概周期解

研究了一类具 logistic增长率的 SIS传染病模型 .得到持久性与概周期解存在以及全局一致渐近稳定的充分条件 .     

An integrable SIS model

We provide a demonstration of the integrability of a classical model of an infectious disease which neither kills nor induces autoimmunity by means of the Painlevé analysis and use the Lie theory of transformation groups to present an explicit solution.     

Wide-band low noise MM-wave SIS mixers with a single tuning element

Several SIS quasiparticle mixers have been designed and tested for the frequency range from 80 to 115 GHz. The sliding backshort is the only adjustable RF tuning element. The RF filter reactance is used as a fixed RF matching element. A mixer which uses a single 2×2 m² Pb-alloy junction in a quarter-height waveguide mount has a coupled conversion gain of G_M(DSB)=2.6±0.5 dB with an associated noise temperature of T_M(DSB)=16.4±1.8 K at the best DSB operation point. The receiver noise temperature T_R(DSB) is 27.5±0.8 K for the mixer test apparatus. This mixer provides a SSB receiver noise temperature below 50 K over the frequency range from 91 to 96 GHz, the minimum being T_R(SSB)=44±4 K. Another mixer with an array of five 5×5 m² junctions in series in a full-height wave-guide mount has much lower noise temperature T_M(DSB)=6.6±1.6 K, but less gain G_M(DSB)=–5.1±0.5 dB.Contribution of the U.S. Government, not subject to copyright     

一类具有饱和发生率和治疗的SIS传染病模型的后向分支及动力学行为

研究了一类具有饱和发生率和治疗的SIS传染病模型的平衡点的后向分支和动力学性质。假定在治疗能力之内时治疗率是与染病者的数量成比例的,当染病者的数量超过了治疗能力承受的界限时,治疗函数为某一常数形式。研究发现,如果治疗能力较小时,模型将出现后向分支现象,分析的结果表明仅靠降低基本再生数到1以下并不一定能够使疾病根除。