Roles and mechanisms of the CD38/cyclic adenosine diphosphate ribose/Ca2+ signaling pathway

published_or_final_versio

Rashba spin-orbit coupling and spin relaxation in silicon quantum wells

Silicon is a leading candidate material for spin-based devices, and two-dimensional electron gases (2DEGs) formed in silicon heterostructures have been proposed for both spin transport and quantum dot quantum computing applications. The key parameter for these applications is the spin relaxation time. Here we apply the theory of D'yakonov and Perel' (DP) to calculate the electron spin resonance linewidth of a silicon 2DEG due to structural inversion asymmetry for arbitrary static magnetic field direction at low temperatures. We estimate the Rashba spin-orbit coupling coefficient in silicon quantum wells and find the $T_{1}$ and $T_{2}$ times of the spins from this mechanism as a function of momentum scattering time, magnetic field, and device-specific parameters. We obtain agreement with existing data for the angular dependence of the relaxation times and show that the magnitudes are consistent with the DP mechanism. We suggest how to increase the relaxation times by appropriate device design.Comment: Extended derivations and info, fixed typos and refs, updated figs and data. Worth a re-downloa

Gate-Controlled Electron Spin Resonance in a GaAs/AlGaAs Heterostructure

The electron spin resonance (ESR) of two-dimensional electrons is investigated in a gated GaAs/AlGaAs heterostructure. We found that the ESR resonance frequency can be turned by means of a gate voltage. The front and back gates of the heterostructure produce opposite g-factor shift, suggesting that electron g-factor is being electrostatically controlled by shifting the equilibrium position of the electron wave function from one epitaxial layer to another with different g-factors

Was it worth it? Benefits of transcatheter aortic valve implantation from a patient's perspective:Benefits of transcatheter aortic valve implantation from a patient's perspective

OBJECTIVES: Transcatheter aortic valve implantation (TAVI) is an important treatment option for patients with severe aortic stenosis. To improve patient selection, shared decision‐making is recommended to elicit patients' treatment expectations and goals. We assessed patients' expectations and goals before TAVI treatment and whether these were met after treatment. Additionally, we evaluated how meeting these goals aligned with quality of life and functional recovery. DESIGN: A mixed method study. SETTING: An academic medical center. PARTICIPANTS: Seventy‐four patients undergoing TAVI between 2015 and 2017. MEASUREMENTS: Patients' expectations and goals were assessed qualitatively before treatment. Six to twelve months post procedure, quality of life was measured with the EuroQuol‐5D and any change in the number of dependencies in (instrumental) activities of daily living was assessed. RESULTS: Mean age of patients was 81.5 years, and 37.8% were male. Regaining the ability to engage in a specific hobby or activity was the most important treatment goal (33 patients, 54.1%), followed by reducing symptoms (19 patients 31.1%). 66.2% of patients stated that their treatment goal was met. Quality of life was higher in this group, as compared with patients who had not met their treatment goal. Twenty‐three patients (31.1%) showed functional improvement. CONCLUSION: TAVI patients were quite capable of eliciting treatment goals and a majority stated, after treatment, that these had been met patients' experience of treatment benefits regarding these goals had poor alignment with functional outcomes. This raises questions regarding relevant outcome measurements in this population, and could aid in improving shared decision‐making and patient selection for TAVI

Screening Breakdown on the Route toward the Metal-Insulator Transition in Modulation Doped Si/SiGe Quantum Wells

Exploiting the spin resonance of two-dimensional (2D) electrons in SiGe/Si quantum wells we determine the carrier-density-dependence of the magnetic susceptibility. Assuming weak interaction we evaluate the density of states at the Fermi level D(E_F), and the screening wave vector, q_TF. Both are constant at higher carrier densities n, as for an ideal 2D carrier gas. For n < 3e11 cm-2, they decrease and extrapolate to zero at n = 7e10 cm-2. Calculating the mobility from q_TF yields good agreement with experimental values justifying the approach. The decrease in D(E_F) is explained by potential fluctuations which lead to tail states that make screening less efficient and - in a positive feedback - cause an increase of the potential fluctuations. Even in our high mobility samples the fluctuations exceed the electron-electron interaction leading to the formation of puddles of mobile carriers with at least 1 micrometer diameter.Comment: 4 pages, 3 figure