Reliability Implications Research Articles

Converse piezoelectric strain in undoped and Fe-doped AlGaN/GaN heterostructure field effect transistors studied by Raman scattering

Converse piezoelectric strain in undoped and Fe-doped AlGaN/GaN heterostructure field effect transistors (HFETs), i.e. the strain induced by applying bias to a transistor, was studied using micro-Raman scattering spectroscopy as a function of applied source–drain voltage for different GaN buffer doping levels and substrate types. By monitoring the phonon frequency shifts and line width of the E2 and A1(LO) phonon modes of GaN, a considerable piezoelectric strain/stress was found in undoped devices, which exhibited a saturation above 40 V bias. This saturation voltage was used to quantify the deep acceptor concentration in the GaN buffer layer. Using experimental Raman data and numerical modelling of the electric field distribution in the device, it was furthermore established that Fe doping causes confinement of the strain/stress to the vicinity of the AlGaN/GaN interface, i.e. near the electron channel, with potential implications for device reliability. It was concluded that varying the structure and doping in the buffer layer has the potential to modify the converse piezoelectric strain and hence affect reliability issues in AlGaN/GaN HFETs.

Adverse event categorisation across NHS Scotland

This paper describes a scoping of adverse event categories and definitions in use across NHS Scotland and makes recommendations about the categories used. The design involved a network analysis making use of categories and subcategories supplied by 17 different Health Boards via their risk management/clinical governance functions. A total of 128 discrete categories and 1348 subcategories are used across 17 Health Boards (mean number of subcategories used: 164; SD 61; range 56-288). There is some redundancy with around half of all categories (65; 51%) used by one single board and a further 10 (8%) by just two boards. Many health boards use similar subcategories within different categories. This shows conceptual overlap between confounded categories. This overlap has implications for reliability and has been quantified via the network analysis. The eight most frequently used categories across the Health Boards have an average of 14.9 overlaps with other categories, suggesting some degree of variability in how adverse events are captured. This has implications for nationally collated data; however the formal links between categories identified in this work offer the opportunity of reliable data extraction at national level without substantial recoding by individual Health Boards.

ALIGNING SCALES OF CERTIFICATION TESTS

ABSTRACTScores are the most visible and widely used products of a testing program. The choice of score scale has implications for test specifications, equating, and test reliability and validity, as well as for test interpretation. At the same time, the score scale should be viewed as infrastructure likely to require repair at some point. In this report we examine the issue of scale fit—how well the scale fits the intended uses of its scores—for certification tests. Two examples of scale fit are considered: one in which the test has a single threshold that separates the candidate population into pass‐fail groups, and one in which the test is required to support a restricted range of multiple thresholds.

Unipolar recovery of dielectric breakdown in fully silicided high-κ gate stack devices and its reliability implications

We report observations of unipolar recovery of dielectric breakdown in fully silicided NiSi-gate HfSiON–SiOx bilayer dielectric based high-κ metal-insulator-semiconductor (MIS) gate stack, analogous to resistive switching in metal-insulator-metal (MIM) nonvolatile memory devices. The dependence of the recovery voltage on breakdown hardness and filament location is analyzed and the physics behind MIS recovery, governed by joule heating induced oxygen vacancy trap passivation, is explained using failure analysis and statistical investigations. The observed MIS recovery phenomenon can be a tool to design for reliability in novel metal gate high-κ gate stacks.

Is case-specificity content-specificity? An analysis of data from extended-matching questions

Case-specificity, i.e., variability of a subject's performance across cases, has been a consistent finding in medical education. It has important implications for assessment validity and reliability. Its root causes remain a matter of discussion. One hypothesis, content-specificity, links variability of performance to variable levels of relevant knowledge. Extended-matching items (EMIs) are an ideal format to test this hypothesis as items are grouped by topic. If differences pertaining to content knowledge are the main cause of case-specificity, variability across topics should be high and variability across items within the same topic low. We used generalisability analysis on results of a written test composed of 159 EMIs sat by two cohorts of general practice trainees at one university. Two hundred and twenty-seven trainees took part. The variance component attributed to subjects was small. Variance attributed to topics was smaller than variance attributed to items. The main source of error was interaction between subjects and items, accounting for two-thirds of error. The generalisability D study revealed that for the same total number of items, increasing the number of topics results in a higher G coefficient than increasing the number of items per topic. Topical knowledge does not seem to explain case-specificity observed in our data. Structure of knowledge and reasoning strategy may be more important, in particular pattern-recognition which EMIs were designed to elicit. The causal explanations of case-specificity may be dependent on test format. Increasing the number of topics with fewer items each would increase reliability but also testing time.

Visual learning with reliable and unreliable features

Existing studies of sensory integration demonstrate how the reliabilities of perceptual cues or features influence perceptual decisions. However, these studies tell us little about the influence of feature reliability on visual learning. In this article, we study the implications of feature reliability for perceptual learning in the context of binary classification tasks. We find that finite sets of training data (i.e., the stimuli and corresponding class labels used on training trials) contain different information about a learner's parameters associated with reliable versus unreliable features. In particular, the statistical information provided by a finite number of training trials strongly constrains the set of possible parameter values associated with unreliable features, but only weakly constrains the parameter values associated with reliable features. Analyses of human subjects' performances reveal that subjects were sensitive to this statistical information. Additional analyses examine why subjects were sub-optimal visual learners.

Wind power modelling and the determination of capacity credit in an electric power system

Wind is an important energy source and is regarded as a valuable alternative to traditional electric power-generating sources. There is an increasing interest in the development and use of wind energy as a substitute for more conventional energy because of its high potential and minimum impact on the environment. Generating capacity from wind power behaves quite differently than that from more conventional generating sources, as the wind is highly variable and is both site and terrain specific. These conditions dictate the need to develop suitable models and procedures to assess the reliability implications associated with integrating wind power in electric power systems. This paper presents an approach to modelling wind power in generating-capacity reliability studies using an autoregressive moving average (ARMA) time series. The technique is illustrated by application to a representative test system using wind data from a site in Saskatchewan, Canada. The test system is used to illustrate the effect on the system risk of adding increasing amounts of wind capacity to a conventional generating system. The risk is assessed using the loss of load expectation and loss of energy expectation indices. The generating capacity credit attributable to wind power is expressed in terms of the increase in system peak load-carrying capability at the criterion risk level. These analyses are extended to consider multiple wind sites with dependent and independent wind regimes.

Reliability Implications of Bias-Temperature Instability in Digital ICs

Bias temperature instability (BTI) is one of the major reliability challenges in nanoscale CMOS technology. This article investigates the severity of such degradation in logic and memory circuits. The simulation results reveal that BTI poses severe constraints on reliable memory design, especially in the presence of random process variations.

The influence of wind generation on power system reliability and the possible use of hydrogen storages

The aim of this study is to simulate the impact of non-programmable generation sources, in particular wind farms, on the reliability of an electric power system. A probabilistic model has been implemented, to evaluate the influence of wind generation on the amount of secondary/tertiary generating reserve, required in a hydro-thermoelectric system to maintain a certain level of reliability. A case study, calibrated on the electric system of one of the largest Italian islands, shows the critical issues associated with over-generation events, basically due to an underestimation of wind production. Three possible policies, to be adopted during real-time by the Independent System Operator (ISO) in order to face such events, are simulated and discussed in terms of system reliability and costs for balancing operation. The use of hydrogen storages, managed by the ISO to cope with over-generation contingencies, is proposed and analyzed in different scenarios of wind penetration, assessing the payback time of the storage devices also considering the economic implications of system reliability.

Reliability of SiGe HBTs for Power Amplifiers—Part I: Large-Signal RF Performance and Operating Limits

This paper examines the performance and reliability implications associated with aggressively biased cascode SiGe HBT power-amplifier cores under large-signal RF operating conditions. The role of high-power RF stress on device degradation and failure is examined in detail. General expressions for a large-signal RF safe-operating area, which account for the effect of load impedance on the dynamic output current and voltage characteristics, are presented. These show excellent agreement with experimental results. Useful operating guidelines for reliable large-signal operation are provided.

Interobserver reproducibility of histologic parameters of melanoma deposits in sentinel lymph nodes

: Histologic parameters of melanoma deposits in sentinel lymph nodes (SLNs) have been shown to be predictive of clinical outcome and the presence or absence of tumor in non-SLNs, but assessment of these parameters is prone to interobserver variation. : Histologic sections of 44 SLNs containing metastatic melanoma were examined by 7 pathologists. Parameters assessed included cross-sectional area of tumor deposits, cross-sectional area of SLNs, percentage of SLN area involved by tumor calculated from the 2 previous parameters, estimated percentage of SLN area involved by tumor, tumor penetrative depth, location of tumor within the SLN, and presence of extracapsular spread. Levels of interobserver agreement were measured by using intraclass correlation coefficients (ICC). : There was good to excellent interobserver agreement on measurement of quantitative parameters: maximal size of largest tumor deposits, calculated area of 3 largest tumor deposits, percentage of the area of SLN involved by tumor, and tumor penetrative depth (ICC, 0.88, 0.73, 0.68, and 0.83, respectively). There was moderate agreement on the evaluation of subcapsular versus nonsubcapsular location of tumor deposits (ICC = 0.50). Agreement on assessment of extracapsular spread was fair (ICC = 0.39). : Assessment of some of the quantitative parameters was highly reproducible between pathologists. However, evaluation of the location of tumor deposits within SLNs and assessment of extracapsular spread was less reproducible. Clearer definitions and training can be expected to improve the reproducibility of assessment. These results have important implications for reliability and reproducibility of these parameters in staging, prediction of outcome, and clinical management of melanoma patients. Cancer 2009. (c) 2009 American Cancer Society.

Sourcing Decisions with Stochastic Supplier Reliability and Stochastic Demand

Supplier sourcing strategies are a crucial factor driving supply chain success. In this paper, we investigate the implications of uncertain supplier reliability on a firm's sourcing decisions in an environment with stochastic demand. In particular, we characterize specific conditions under which a firm should choose a single versus multiple supplier sourcing strategy. In an environment with both uncertain demand and supply, we characterize the total order quantity, the number of suppliers selected for order placement, and the allocation of the total order quantity among these selected suppliers. For deeper managerial insight, we also examine the sensitivity of the optimal sourcing decisions to interactions between uncertainties in product demand and supply reliability. We show that sourcing from a single supplier is an optimal strategy for environments characterized by high levels of demand uncertainty or high salvage values. A numerical analysis based on data obtained from an office products retailer further reinforces our analytical results. In addition, we also find that when minimal order quantities are imposed, there are situations where it is not optimal to place an order with the lowest cost supplier.

Characterization of Genetically Diverse HIV Type 1 from a London Cohort: Near Full-Length Genomic Analysis of a Subtype H Strain

HIV-1 is characterized by an exceptional level of sequence diversity and a rapid rate of evolution. HIV diversity has implications for reliability of assays designed to detect and monitor infection, pathogenesis, disease progression, response to antiviral therapeutics, resistance pathways, and vaccine development. In the present study, HIV-1 strain diversity was assessed for a small clinical cohort (n = 15) from London, England at risk for infection with non-subtype B strains. Analysis of gag p24, pol IN, and env gp41 IDR revealed the presence of five subtypes (A, B, C, D, H), CRF02_AG, and four unique recombinant forms. Due to the paucity of complete subtype H genomes available, we performed near full-length genome sequence analysis on the candidate subtype H strain, designated as 00GB.AC4001. Phylogenetic analysis revealed that it formed a monophyletic cluster with the three available subtype H reference sequences. Bootscanning analysis confirmed that 00GB.AC4001 represents a new nonrecombinant subtype H genome.

Modeling and direct extraction of band offset induced by stress engineering in silicon-on-insulator metal-oxide-semiconductor field effect transistors: Implications for device reliability

We study the performance and reliability of metal-oxide-semiconductor field effect transistors fabricated on strained and unstrained silicon on insulator substrates, sSOI and SOI, respectively. The biaxial strain strongly enhances electron mobility and changes the threshold voltage, Vt, of the devices. We show that the Vt shift in the “ideal SOI structures,” i.e., with no oxide defects, is due to the conduction band offset induced by strain ΔEc and therefore can be used for the stress monitoring. The biaxial strain also affects the gate oxide leakage current. A new method to extract ΔEc from the leakage current measurements is proposed. This method is less sensitive to the gate oxide defects than the one based on Vt shift. A complete modeling of leakage current in SOI and sSOI transistors is presented. Due to the strong confinement at the Si/SiO2 interface the leakage current in the Fowler–Nordheim (FN) regime mainly results from electron tunneling in the subband associated to the ground level E0Δ2. A simple FN model is therefore used to extract the ΔEc from the variation in the effective barrier height ϕbFN between the Si film and the SiO2 oxide. Based on this experimental and accurate extraction of ΔEc, realistic values of the deformation potentials in Si are finally proposed. The final part of the paper discusses the different implications of this band offset ΔEc on device performance and reliability. It is demonstrated that strained devices exhibit reduced leakage currents and a superior reliability, in terms of interface state density and oxide breakdown, than unstrained devices.

Practical implications of data reliability and treatment integrity monitoring.

Data reliability and treatment integrity have important implications for clinical practice because they can affect clinicians' abilities to accurately judge the efficacy of behavioral interventions. Reliability and integrity data also allow clinicians to provide feedback to caregivers and to adjust interventions as needed. We present reasons why reliability and integrity measures are paramount in clinical work, discuss events that may result in decreased reliability or integrity, and provide several efficient means for collecting data and calculating reliability and integrity measures.

Magnet Reliability in the Fermilab Main Injector and Implications for the ILC

The International Linear Collider reference design requires over 13000 magnets, of approximately 135 styles, which must operate with very high reliability. The Fermilab Main Injector represents a modern machine with many conventional magnet styles, each of significant quantity, that has now accumulated many hundreds of magnet-years of operation. We review here the performance of the magnets built for this machine, assess their reliability and categorize the failure modes, and discuss implications for reliability of similar magnet styles expected to be used at the ILC.

Economic and energy impacts from participation in the regional greenhouse gas initiative: A case study of the State of Maryland

Tradable emissions allowance systems to reduce carbon emissions are increasingly promoted as means to mitigate climate change. This paper briefly reviews the application of such systems at the global, regional, and corporate scales. Given the recent expansion of cap-and-trade systems at the regional level, the paper concentrates on energy and economic implications at that level, using the decision of the State of Maryland, USA, to join the Regional Greenhouse Gas Initiative as an illustration. The paper presents the results of an analysis of the implications for technology choice, generation capacity, energy reliability, and cost to ratepayers of that decision, combining a national electricity market model with a regional model that includes market power and an economic impact model. The results suggest several issues that will be key to the acceptability and effectiveness of cap-and-trade systems for regional climate change mitigation policy, including rules for distribution of allowances and subsidies for energy efficiency programs.

URETERAL FROZEN SECTIONS AT THE TIME OF RADICAL CYSTECTOMY: RELIABILITY AND CLINICAL IMPLICATIONS

You have accessJournal of Urology1 Apr 2008URETERAL FROZEN SECTIONS AT THE TIME OF RADICAL CYSTECTOMY: RELIABILITY AND CLINICAL IMPLICATIONS Naji J Touma, Mazen Abdelhady, Jonathan I Izawa, and Joseph L Chin Naji J ToumaNaji J Touma More articles by this author , Mazen AbdelhadyMazen Abdelhady More articles by this author , Jonathan I IzawaJonathan I Izawa More articles by this author , and Joseph L ChinJoseph L Chin More articles by this author View All Author Informationhttps://doi.org/10.1016/S0022-5347(08)61566-9AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail "URETERAL FROZEN SECTIONS AT THE TIME OF RADICAL CYSTECTOMY: RELIABILITY AND CLINICAL IMPLICATIONS." The Journal of Urology, 179(4S), p. 533 © 2008 by American Urological AssociationFiguresReferencesRelatedDetails Volume 179Issue 4SApril 2008Page: 533 Advertisement Copyright & Permissions© 2008 by American Urological AssociationMetricsAuthor Information Naji J Touma More articles by this author Mazen Abdelhady More articles by this author Jonathan I Izawa More articles by this author Joseph L Chin More articles by this author Expand All Advertisement PDF downloadLoading ...

Design techniques for reducing the impact of component variations on narrow-band low noise amplifiers

Given the increasing demand for integrated wireless systems in system-on-chip technology, narrow-band low noise amplifier (LNA) designs must be robust against variations in device parameters and passive component values to improve manufacturing yield for high volume applications. In this paper, we develop two design techniques for reducing the impact of component variations on narrow-band LNA performance. The results demonstrate that by increasing the bandwidth of the narrow-band LNA and applying more conservative design constraints, we can mitigate the reliability implications of process variations on impedance matching, gain, and power consumption.

Assertions of "future dangerousness" at federal capital sentencing: Rates and correlates of subsequent prison misconduct and violence.

The federal prison disciplinary records of federal capital inmates (n=145) who were sentenced to life without possibility of release (LWOP) by plea bargain, pre-sentencing withdrawal of the death penalty, or jury determination were retrospectively reviewed (M=6.17 years post-admission). Disaggregated prevalence rates were inversely related to infraction severity: serious infraction =0.324, assaultive infraction =0.207, serious assault =0.09, assault with moderate injury =0.007, assault with major injuries or death =0.00. Frequency rates of misconduct were equivalent to other high-security federal inmates (n=18,561), regardless of infraction severity. Government assertions of "future dangerousness" as a nonstatutory aggravating factor were not predictive of prison misconduct. These findings inform federal capital risk assessments and have public policy implications for procedural reliability in death penalty prosecutions.