Generalized lock-in amplifier for precision measurement of high frequency signals

We herein formulate the concept of a generalized lock-in amplifier for the precision measurement of high frequency signals based on digital cavities. Accurate measurement of signals higher than 200 MHz using the generalized lock-in is demonstrated. The technique is compared with a traditional lock-in and its advantages and limitations are discussed. We also briefly point out how the generalized lock-in can be used for precision measurement of giga-hertz signals by using parallel processing of the digitized signals

High Precision Measurements Using High Frequency Signals

Generalized lock-in amplifiers use digital cavities with Q-factors as high as 5X10^8. In this letter, we show that generalized lock-in amplifiers can be used to analyze microwave (giga-hertz) signals with a precision of few tens of hertz. We propose that the physical changes in the medium of propagation can be measured precisely by the ultra-high precision measurement of the signal. We provide evidence to our proposition by verifying the Newton's law of cooling by measuring the effect of change in temperature on the phase and amplitude of the signals propagating through two calibrated cables. The technique could be used to precisely measure different physical properties of the propagation medium, for example length, resistance, etc. Real time implementation of the technique can open up new methodologies of in-situ virtual metrology in material design

Impact of frailty on long-term mortality in older patients receiving intensive care via the emergency department

The aim of this study was to evaluate whether frailty was associated with 6-month mortality in older adults who were admitted to the intensive care unit (ICU) with an illness requiring emergency care. The investigation was a prospective, multi-center, observational study conducted among the ICUs of 17 participating hospitals. Patients >= 65 years of age who were admitted to the ICU directly from an emergency department visit were assessed to determine their baseline Clinical Frailty Scale (CFS) scores before the illness and were surveyed 6 months after admission. Among 650 patients included in the study, the median age was 79 years old, and overall mortality at 6 months was as low as 21%, ranging from 6.2% in patients with CFS 1 to 42.9% in patients with CFS >= 7. When adjusted for potential confounders, CFS score was an independent prognostic factor for mortality (one-point increase in CFS, adjusted risk ratio with 95% confidence interval 1.19 [1.09-1.30]). Quality of life 6 months after admission worsened as baseline CFS score increased. However, there was no association between total hospitalization cost and baseline CFS. CFS is an important predictor of long-term outcomes among critically ill older patients requiring emergent admission

階層型運動方程式による量子散逸系の非線形応答の研究

京都大学0048新制・課程博士博士(理学)甲第17771号理博第3894号新制||理||1562(附属図書館)30578京都大学大学院理学研究科化学専攻(主査)教授 谷村 吉隆, 准教授 安藤 耕司, 教授 寺嶋 正秀学位規則第4条第1項該当Doctor of ScienceKyoto UniversityDGA

Ultrafast Proton/Deuteron Dynamics in Solid Oxide Observed with Infrared Pump-Probe Spectroscopy

We performed pump-probe spectroscopy on OD stretching mode in KTaO3 to explore how a proton/deuteron interacts with the surroundings. We identified the potential anharmonicity and phonon modes which interact with a proton/deuteron, considering the temperature effect

Electron Pumping under Non-Markovian Dissipation: The Role of the Self-Consistent Field

Focusing on electron transport through a periodically driven resonant tunneling diode, we study the generation of a non-vanishing dc-current by applying symmetry breaking external ac fields with phase difference φ in a statically unbiased system. The effect of an environment is investigated using the system-bath Hamiltonian represented by the electron system coupled to harmonic oscillator modes with a Drude–Lorentz spectral density. To carry out simulations, we use the hierarchal equations of motion approach in the Wigner representation including a self-consistently constructed electric field that is determined from the electron distribution using the Poisson equation. We show that the maximal pumping current at a phase difference near φ = π/2 is strongly influenced by the system-bath coupling strength. The effect of dissipation is diminished if the self-consistent part of the potential is ignored

Antenna-enhancements of molecular vibrational responses in ultrafast infrared spectroscopy

We demonstrate surface-enhanced ultrafast vibrational spectroscopy employing periodic arrays of infrared-resonant gold nanoantennas. The antenna-enhancements of molecular vibrational responses are analytically formulated with a simple coupled-dipole model, and the linear/nonlinear local signal enhancements are evaluated to be ~104 and 107, respectively