The Role of Depressive Symptomatology in Peri- and Post-Menopause

Objectives: There is evidence that menopausal symptoms manifested at peri-menopause occur less fre- quently when compared to the symptoms experienced at post-menopause. The aim of this study was to investigate this and to test the hypothesis that depressive symptomatology mediates the relationship between menopausal stage and symptom frequency. Methods: This cross-sectional study included 213 women (M age = 52 years), of whom 125 were peri- and 88 post-menopausal. Measures comprised the Center for Epidemiologic Studies-Depression scale (CES-D) and the Women’s Health Questionnaire (WHQ) vasomotor symptoms and somatic symptoms subscales. Results: Multiple mediated regression analyses provided evidence that somatic symptoms and vasomotor symptoms were less frequent at post- compared to peri-menopause, and that these differences were mediated by depressive symptomatology. Multivariate effect sizes ranged from small to moderate, and univariate effect sizes were uniformly small with wide confidence intervals. Conclusions: The frequency of vasomotor and somatic symptoms appears to increase with depressed affect. The management of symptoms could include interventions of a psychotherapeutic nature, which may offset this effect, particularly in women for whom depressive symptoms are a feature of the climac- teric syndrome. The extent to which depression and the climacteric syndrome may be causally related to one another remains unclear and longitudinal research should further examine the mechanisms of this association

Global modeling of microwave transistors using a full-band Cellular Monte Carlo/full-wave Maxwell simulator

A full-band Cellular Monte Carlo (CMC)/full-wave Maxwell simulator is presented and applied to the global modeling of high-frequency submillimeter and microwave transistors. In this work, global modeling refers to the combination of solid-state device physics with full-wave electromagnetics (EM). This approach attempts to provide a more complete physical model of the device and its interaction with the surrounding environment. Two different three-dimensional EM solvers have been implemented and self-consistently coupled to an existing full-band, CMC device simulator. The first is based upon the conventional finite-difference time-domain (FDTD) approach. The second one utilizes the alternate-direction implicit (ADI) method which relaxes the Courant-Fredericks-Levy (CFL) stability criterion and reduces the total number of simulation timesteps required. Both solvers are implemented with state-of-the-art perfectly matched layer (PML) absorbing boundary conditions to effectively truncate the working simulation space. The numerical methods and techniques utilized within the full-band CMC device simulator and both EM solvers are explained in detail and benchmarking results are presented to validate the accuracy of the employed techniques. The coupled full-band/full-wave simulator is then used to study the high-frequency response of metal-semiconductor field effect transistors (MESFETs) via direct S-parameter extraction from coupled device simulations. This work demonstrates the usefulness of this new simulation tool in the development of microwave transistors and submillimeter-wave device technologies

High-performance in0.75Ga0.25As implant-free n-type MOSFETs for low power applications

The performance of implant-free (IF), n-type III-V MOSFETs with an In0.75Ga0.25As channel have been evaluated using a 2D finite-element Monte Carlo device simulator. We investigate the device performance of a set of scaled transistors with gate lengths of 30, 20 and 15 nm at a drain bias of 0.5 V to determine whether this novel architecture can deliver high drain current at low bias conditions required for high-performance CMOS application

Physical modeling of microwave transistors using a full-band/full-wave simulation approach

In this work, a full-band Cellular Monte Carlo (CMC) device simulator is self-consistently coupled to an alternate-direction implicit (ADI) finite-difference time-domain (FDTD) full-wave solver. This simulation tool is then used to study the high-frequency response of a dual-finger gate GaAs MESFET via direct S-parameter extraction from time-domain simulation result

Effect of Interface State Trap Density on the Performance of Scaled Surface Channel In0.3Ga0.7As MOSFETs

The effect of interface state trap density, D-it, on the I-D-V-G characteristics of scaled surface channel MOSFETs based on In0.3Ga0.7As channel has been investigated using drift-diffusion simulations. We have developed a methodology to include arbitrary energy distributions of interface states into the input simulation decks and analysed their impact on subthreshold characteristics and drive current when these devices are scaled from a gate length of 65 nm to 35 nm, 25 nm and 18 nm. The distributions of interface states having high density tails that extend into the conduction band can significantly impact the subthreshold performance of the larger gate length device. Furthermore, the same distributions have smaller impact on the performance of shorter channel devices which were designed with smaller high-kappa thicknes

Effect of interface state trap density on the characteristics of n-type, enhancement-mode, implant-free In0.3Ga0.7As MOSFETs

The effect of interface state trap density, D-it, on the device characteristics of n-type, enhancement-mode, implant-free (IF) In0.3Ga0.7As MOSFETs [1,2] has been investigated using a commercial drift-diffusion (DD) device simulation tool. Methodology has been developed to include arbitrary D-it, distributions in the input simulation decks to more accurately fit the measured subthreshold characteristics of recently reported 1.0 mu m gate length IF In0.3Ga0.7As MOSFETs [3]. The impact of interface states on a scaled 30 nm gate length IF MOSFET is also reported

Impact of interface state trap density on the performance characteristics of different III-V MOSFET architectures

The effect of interface state trap density, D-it, on the current-voltage characteristics of four recently proposed III-V MOSFET architectures: a surface channel device, a flat-band implant-free HEMT-like device with delta-doping below the channel, a buried channel design with delta-doping, and implant-free quantum-well HEMT-like structure with no delta-doping, has been investigated using TCAD simulation tools. We have developed a methodology to include arbitrary energy distributions of interface states into the input simulation decks and analysed their impact on subthreshold characteristics and drive current. The distributions of interface states having high density tails that extend to the conduction band can significantly impact the subthreshold performance in both the surface channel design and the implant-free quantum-well HEMT-like structure with no delta-doping. Furthermore, the same distributions have little or no impact on the performance of both flat-band implant-free and buried channel architectures which operate around the midgap