Hysteresis-Free Nanosecond Pulsed Electrical Characterization of Top-Gated Graphene Transistors

We measure top-gated graphene field effect transistors (GFETs) with nanosecond-range pulsed gate and drain voltages. Due to high-k dielectric or graphene imperfections, the drain current decreases ~10% over time scales of ~10 us, consistent with charge trapping mechanisms. Pulsed operation leads to hysteresis-free I-V characteristics, which are studied with pulses as short as 75 ns and 150 ns at the drain and gate, respectively. The pulsed operation enables reliable extraction of GFET intrinsic transconductance and mobility values independent of sweep direction, which are up to a factor of two higher than those obtained from simple DC characterization. We also observe drain-bias-induced charge trapping effects at lateral fields greater than 0.1 V/um. In addition, using modeling and capacitance-voltage measurements we extract charge trap densities up to 10^12 1/cm^2 in the top gate dielectric (here Al2O3). Our study illustrates important time- and field-dependent imperfections of top-gated GFETs with high-k dielectrics, which must be carefully considered for future developments of this technologyComment: to appear in IEEE Transactions on Electron Devices (2014

Size Reduction and Harmonics Suppression in Microwave Power Dividers: A Comprehensive Review

In this paper, several types of microstrip power divider are studied and compared in terms of harmonics suppression and size reductions. The importance of this research lies in the fact that power dividers are critical components in various communication systems, and their performance directly affects the overall system efficiency. The conventional structure of the power divider has an acceptable performance at operating frequency in terms of excellent output ports isolation, low insertion loss, and high return loss, but occupies large size and passes unwanted signals at higher frequencies along with desired signal without any suppression. Harmonics are popular distortion and has different distortion impacts in many different facilities. Recently, several techniques are introduced to overcome these drawbacks. Applied open stubs, applied resonators, lumped reactive components such as capacitors and inductors, coupled lines, defected ground structure (DGS), and electronic band gaps are common methods, which are widely used to overcome these drawbacks. Finally, the study results show that the resonator-based power dividers and coupled-line-based power dividers have good performances in terms of size reduction and harmonic suppression but increase insertion loss parameter. Furthermore, the lumped reactive component-based power dividers and applied DGS and electromagnetic bandgap cells suppress unwanted harmonics, but they need extra process to fabrication, which is undesirable. Moreover, the open-stub-based power dividers have moderate performance with simple structure, but size reduction and harmonics suppression are not so superior in this method

Dose-escalated salvage radiotherapy after radical prostatectomy in high risk prostate cancer patients without hormone therapy: outcome, prognostic factors and late toxicity

Purpose: Evaluation of dose escalated salvage radiotherapy (SRT) in patients after radical prostatectomy (RP) who had never received antihormonal therapy. To investigate prognostic factors of the outcome of SRT and to analyze which patient subsets benefit most from dose escalation. Materials and methods: Between 2002 and 2008, 76 patients were treated in three different dose-groups: an earlier cohort treated with 66 Gy irrespective of pre-RT-characteristics and two later cohorts treated with 70 Gy or 75 Gy depending on pre-RT-characteristics. Biochemical-relapse-free-survival (bRFS), clinical-relapse-free-survival (cRFS) and late toxicity were evaluated. Results: Four-year bRFS and cRFS were 62.5% and 85%. Gleason score <8, positive surgical resection margin (PSRM) and low PSA (<= 0.5 ng/ml) before SRT resulted in higher bRFS. Analysis of the whole group showed no clear dose-outcome relationship. Patients with PSRM, however, had improved bRFS when escalating >66 Gy. While >70 Gy did not improve the overall results, 4-year bRFS for patients with manifest local recurrence in the high-dose group was still comparable to those without manifest local recurrences. No grade 4 and minimal grade 3 gastrointestinal and urinary toxicity were observed. Conclusions: Dose-escalated SRT achieves high biochemical control. The data strongly support the application of at least 70 Gy rather than 66 Gy. They do not prove positive effects of doses >70 Gy but do not disprove them as these doses were only applied to an unfavorable patients selection

Determining project characteristics and critical path by a new approach based on modified NWRT method and risk assessment under an interval type-2 fuzzy environment

In this paper with respect to the importance of risks in real-world projects and ability of interval type-2 fuzzy sets (IT2FSs) to tackle the uncertainty, a new approach is introduced to consider risks and the correlation among risk factors by subjective judgments of experts on the probability and impact under IT2FSs. Furthermore, a new impact function for considering the correlation among the risk factors are extended under an IT2F environment. Moreover, a new subtraction operator is introduced for the critical path analysis. The node-weighted rooted tree (NWRT) method is modified based on the proposed new operator to avoid producing negative number for characteristics of each activity. Also, in order to cope with the uncertainty of the projects, NWRT method is developed under the IT2FSs. Eventually, to illustrate the validity and capability of the proposed method, two examples from the literature are solved and compared

In situ, 3D characterization of the deformation mechanics of a superelastic NiTi shape memory alloy single crystal under multiscale constraint

Microstructural elements in NiTi shape memory alloys (SMAs) e precipitates, phase boundaries, inclusions

Frailty predicts incident atrial fibrillation in women but not in men : The Kuopio Ischaemic Heart Disease Risk Factor Study

INTRODUCTION: Frailty and atrial fibrillation (AF) are common aging problems and increasing globally. The association(s) between frailty and AF have been inconclusive. The purpose of this prospective population-based cohort was to investigate the associations between frailty and incident atrial fibrillation (AF) in older men and women. METHODS: In total 839 participants, women (n=458) and men (n=381), aged 61-74 years from the Kuopio Ischaemic Heart Disease Risk Factor Study were included (March 1, 1998, to December 31, 2001). At the baseline, among frailty prevalence was 49.3% (n=414), and non-frailty 50.7% (n=425) of the total population. Frailty was ascertained with the presence of 3-5 and prefrailty 1-2 of the following criteria: weight loss (highest 20% over 7 years), self-reported tiredness, weakness (measured by handgrip strength), slow walking speed (walking pace), and low physical activity (lowest 20%). AF events were obtained by record linkages from the national computerized hospitalization registry in Finland up to December 31, 2019. Multivariate Cox proportional hazard regression estimated the hazard ratio (HR) of incident events, adjusted for potential confounders. RESULTS: During the mean follow-up of 14.2 years, 288 AF cases (169 women; 119 men) occurred. After adjustment for possible confounders, the HRs (95% confidence intervals (CIs)) for AF was 1.46 (1.48-1.85) in the frail population, compared to the non-frail group. The association was observed only among older frail women [multivariable-adjusted HR 1.78, 95% CI (1.28-2.48)], (P for interaction=0.04). No statistically significant associations were observed between frailty and future AF incident among men (multivariable-adjusted HRs 1.12, 95% CI (0.77-1.63). CONCLUSIONS: In this population based epidemiological cohort, the risk of developing AF was increased in women affected by frailty at baseline but not in men

Men, rheumatoid arthritis, psychosocial impact and self-management: A narrative review.

Rheumatoid arthritis (RA) is a chronic disease affecting fewer men than women. We systematically reviewed the literature on impact and self-management of RA men. Twenty eight papers were included, and grouped into two categories: Psychosocial impact of RA; and Coping and self-management. This review finds gender differences relating to quality of life; work; distress; self-management; coping; and support. We conclude there is a dearth of literature focussing on RA men only, and mixed gender studies include insufficient men to draw strong conclusions about men. Thus, further research is needed to understand the support needs of men with RA in depth

Ethylene supports colonization of plant roots by the mutualistic fungus Piriformospora indica

The mutualistic basidiomycete Piriformospora indica colonizes roots of mono- and dicotyledonous plants, and thereby improves plant health and yield. Given the capability of P. indica to colonize a broad range of hosts, it must be anticipated that the fungus has evolved efficient strategies to overcome plant immunity and to establish a proper environment for nutrient acquisition and reproduction. Global gene expression studies in barley identified various ethylene synthesis and signaling components that were differentially regulated in P. indica-colonized roots. Based on these findings we examined the impact of ethylene in the symbiotic association. The data presented here suggest that P. indica induces ethylene synthesis in barley and Arabidopsis roots during colonization. Moreover, impaired ethylene signaling resulted in reduced root colonization, Arabidopsis mutants exhibiting constitutive ethylene signaling, -synthesis or ethylene-related defense were hyper-susceptible to P. indica. Our data suggest that ethylene signaling is required for symbiotic root colonization by P. indica