Generalized Mittag-Leffler stability of fractional impulsive differential system

This paper establishes sufficient conditions for Generalized Mittag-Leffler stability of a class of impulsive fractional differential system with Hilfer order. The analysis extends through both, instantaneous and non-instantaneous impulsive conditions. The theory utilizes continuous Lyapunov functions, to ascertain the stability conditions. An example is given discussing for various ranges

Properties of relaxed trajectories of non-linear fractional impulsive control systems

A non-convex control system governed by a nonlinear impulsive evolution equation of Hilfer fractional order in a Banach space is considered. The existence of admissible state-control pair is established. Then the introduction of suitable measure-valued control convexifies the system, and the relaxed system is obtained. Further, the relaxation theorem for the described class is proved along with the existence of optimal relaxed control.Comment: 21 page

Commercialization of low temperature copper thermocompression bonding for 3D integrated circuits

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2008.Includes bibliographical references (p. 84-87).Wafer bonding is a key process and enabling technology for realization of three-dimensional integrated circuits (3DIC) with reduced interconnect delay and correspondingly increased circuit speed and decreased power dissipation, along with an improved form factor and portability. One of the most recent novel and promising wafer bonding approaches to realizing 3DIC is Low Temperature Thermocompression (LTTC) bonding using copper (Cu) as the bonding interface material. This thesis investigates the LTTC bonding approach in terms of its technological implications in contrast to other conventional bonding approaches. The various technological aspects pertaining to LTTC are comprehensively explored and analyzed. In addition to this, the commercialization potential for this technology is also studied and the economic viability of this process in production is critically evaluated using suitable cost models. Based on the technological and economic outlook, the potential for commercialization of LTTC is gauged.by Raghavan Nagarajan.M.Eng

Molecular Bridges Link Monolayers of Hexagonal Boron Nitride during Dielectric Breakdown

We use conduction atomic force microscopy (CAFM) to examine the soft breakdown of monocrystalline hexagonal boron nitride (h-BN) and relate the observations to the defect generation and dielectric degradation in the h-BN by charge transport simulations and density functional theory (DFT) calculations. A modified CAFM approach is adopted, whereby 500 7 500 nm2 to 3 7 3 μm2 sized metal/h-BN/metal capacitors are fabricated on 7 to 19 nm-thick h-BN crystal flakes and the CAFM tip is placed on top of the capacitor as an electrical probe. Current-voltage (I-V) sweeps and time-dependent dielectric breakdown measurements indicate that defects are generated gradually over time, leading to a progressive increase in current prior to dielectric breakdown. Typical leakage currents are around 0.3 A/cm2 at a 10 MV/cm applied field. DFT calculations indicate that many types of defects could be generated and contribute to the leakage current. However, three defects created from adjacent boron and nitrogen monovacancies exhibit the lowest formation energy. These three defects form molecular bridges between two adjacent h-BN layers, which in turn "electrically shorts"the two layers at the defect location. Electrical shorting between layers is manifested in charge transport simulations, which show that the I-V data can only be correctly modeled by incorporating a decrease in effective electrical thickness of the h-BN as well as the usual increase in trap density, which, alone, cannot explain the experimental data. An alternative breakdown mechanism, namely, the physical removal of h-BN layers under soft breakdown, appears unlikely given the h-BN is mechanically confined by the electrodes and no change in AFM topography is observed after breakdown. High-resolution transmission electron microscope micrographs of the breakdown location show a highly localized (<1 nm) breakdown path extending between the two electrodes, with the h-BN layers fractured and disrupted, but not removed

Net ultrafiltration prescription and practice among critically ill patients receiving renal replacement therapy : a multinational survey of critical care practitioners

Objectives: To assess the attitudes of practitioners with respect to net ultrafiltration prescription and practice among critically ill patients with acute kidney injury treated with renal replacement therapy. Design: Multinational internet-assisted survey. Setting: Critical care practitioners involved with 14 societies in 80 countries. Subjects: Intensivists, nephrologists, advanced practice providers, ICU and dialysis nurses. Intervention: A cross-sectional survey. Measurement and Main Results: Of 2,567 practitioners who initiated the survey, 1,569 (61.1%) completed the survey. Most practitioners were intensivists (72.7%) with a median duration of 13.2 years of practice (interquartile range, 7.2-22.0 yr). Two third of practitioners (71.0%; regional range, 55.0-95.5%) reported using continuous renal replacement therapy with a net ultrafiltration rate prescription of median 80.0 mL/hr (interquartile range, 49.0-111.0 mL/hr) for hemodynamically unstable and a maximal rate of 299.0 mL/hr (interquartile range, 200.0-365.0 mL/hr) for hemodynamically stable patients, with regional variation. Only a third of practitioners (31.5%; range, 13.7-47.8%) assessed hourly net fluid balance during continuous renal replacement therapy. Hemodynamic instability was reported in 20% (range, 20-38%) of patients and practitioners decreased the rate of fluid removal (70.3%); started or increased the dose of a vasopressor (51.5%); completely stopped fluid removal (35.8%); and administered a fluid bolus (31.6%), with significant regional variation. Compared with physicians, nurses were most likely to report patient intolerance to net ultrafiltration (73.4% vs 81.3%; p = 0.002), frequent interruptions (40.4% vs 54.5%; p < 0.001), and unavailability of trained staff (11.9% vs 15.6%; p = 0.04), whereas physicians reported unavailability of dialysis machines (14.3% vs 6.1%; p < 0.001) and costs associated with treatment as barriers (12.1% vs 3.0%; p < 0.001) with significant regional variation. Conclusions: Our study provides new knowledge about the presence and extent of international practice variation in net ultrafiltration. We also identified barriers and specific targets for quality improvement initiatives. Our data reflect the need for evidence-based practice guidelines for net ultrafiltration

Retrospective evaluation of whole exome and genome mutation calls in 746 cancer samples

Funder: NCI U24CA211006Abstract: The Cancer Genome Atlas (TCGA) and International Cancer Genome Consortium (ICGC) curated consensus somatic mutation calls using whole exome sequencing (WES) and whole genome sequencing (WGS), respectively. Here, as part of the ICGC/TCGA Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium, which aggregated whole genome sequencing data from 2,658 cancers across 38 tumour types, we compare WES and WGS side-by-side from 746 TCGA samples, finding that ~80% of mutations overlap in covered exonic regions. We estimate that low variant allele fraction (VAF < 15%) and clonal heterogeneity contribute up to 68% of private WGS mutations and 71% of private WES mutations. We observe that ~30% of private WGS mutations trace to mutations identified by a single variant caller in WES consensus efforts. WGS captures both ~50% more variation in exonic regions and un-observed mutations in loci with variable GC-content. Together, our analysis highlights technological divergences between two reproducible somatic variant detection efforts

SIMULATION OF COPPER ELECTRODEPOSITION FOR HIGH ASPECT RATIO THROUGH- SILICON VIA APPLICATIONS IN THREE- DIMENSIONAL INTEGRATED CIRCUITS

Master'sMASTER OF SCIENCE IN ADVANCED MATERIALS FOR MICRO- & NANO- SYSTEM

Statistical characterization and reliability modeling of novel high-K gate dielectric stacks

High-κ (HK) dielectric thin films are currently the most suited insulators for complementary metal-oxide-semiconductor (CMOS) technology in the sub-45nm technology nodes. Hafnium-based dielectrics are widely used in both advanced logic and memory device structures. While reliability studies to qualify the metal gate (MG) – HK stacks have been ongoing for the past few years, there are many unresolved issues regarding the physics and statistical nature of the time dependent dielectric breakdown (TDDB) failure mechanism at the front-end. Some of these issues include (a) deciphering the sequence of BD in the dual layer dielectric stack comprising HfO2 and a thin interfacial layer (IL) of SiOx, (b) studying the origin behind the non-Weibull stochastic nature of BD, (c) decoding the reliability of the individual HK and IL layers, (d) studying the role played by grain boundary (GB) microstructural defects (which cause localized non-random trap generation) on the HK BD statistics, (e) investigating the feasibility of a zero interfacial layer (ZIL) device for sub-16nm nodes from a reliability point of view and (f) extrapolating the device level analysis results to circuit level reliability assessment. These issues form the motivation of this doctoral work. We use electrical characterization, statistical and simulation tools along with failure analysis results as a supporting tool to find solutions to all the above issues listed. Our results clearly indicate IL to be the first layer to BD and at circuit level, failure is most likely to occur by multiple uncorrelated IL soft breakdown (SBD) events rather than a single catastrophic hard breakdown. Percolation BD in the IL layer is also found to be localized around the GB defect lines in the HK film as they serve as low activation barrier paths for oxygen vacancy (defect) diffusion. Based on our electrical observations of post-breakdown recovery in MG-HK MIS logic stacks, we have also been able to explain the origin of resistive switching phenomenon in HfO2-based MIM RRAM considering the role of oxygen vacancy and metal nano-filaments. We report the possibility of operating the same RRAM in two distinct independent switching modes depending on the forming / SET compliance and also quantitatively study the retention reliability of the memory stack at low and high resistance states.DOCTOR OF PHILOSOPHY (EEE