Life-cycle assessment of diesel, natural gas and hydrogen fuel cell bus transportation systems

The Sustainable Transport Energy Programme (STEP) is an initiative of the Government of Western Australia, to explore hydrogen fuel cell technology as an alternative to the existing diesel and natural gas public transit infrastructure in Perth. This project includes three buses manufactured by DaimlerChrysler with Ballard fuel cell power sources operating in regular service alongside the existing natural gas and diesel bus fleets. The life-cycle assessment (LCA) of the fuel cell bus trial in Perth determines the overall environmental footprint and energy demand by studying all phases of the complete transportation system, including the hydrogen infrastructure, bus manufacturing, operation, and end-of-life disposal. The LCAs of the existing diesel and natural gas transportation systems are developed in parallel. The findings show that the trial is competitive with the diesel and natural gas bus systems in terms of global warming potential and eutrophication. Emissions that contribute to acidification and photochemical ozone are greater for the fuel cell buses. Scenario analysis quantifies the improvements that can be expected in future generations of fuel cell vehicles and shows that a reduction of greater than 50% is achievable in the greenhouse gas, photochemical ozone creation and primary energy demand impact categories.     

Monitoring Insulin Aggregation via Capillary Electrophoresis

Early stages of insulin aggregation, which involve the transient formation of oligomeric aggregates, are an important aspect in the progression of Type II diabetes and in the quality control of pharmaceutical insulin production. This study is the first to utilize capillary electrophoresis (CE) with ultraviolet (UV) detection to monitor insulin oligomer formation at pH 8.0 and physiological ionic strength. The lag time to formation of the first detected species in the aggregation process was evaluated by UV-CE and thioflavin T (ThT) binding for salt concentrations from 100 mM to 250 mM. UV-CE had a significantly shorter (5-8 h) lag time than ThT binding (15-19 h). In addition, the lag time to detection of the first aggregated species via UV-CE was unaffected by salt concentration, while a trend toward an increased lag time with increased salt concentration was observed with ThT binding. This result indicates that solution ionic strength impacts early stages of aggregation and β-sheet aggregate formation differently. To observe whether CE may be applied for the analysis of biological samples containing low insulin concentrations, the limit of detection using UV and laser induced fluorescence (LIF) detection modes was determined. The limit of detection using LIF-CE, 48.4 pM, was lower than the physiological insulin concentration, verifying the utility of this technique for monitoring biological samples. LIF-CE was subsequently used to analyze the time course for fluorescein isothiocyanate (FITC)-labeled insulin oligomer formation. This study is the first to report that the FITC label prevented incorporation of insulin into oligomers, cautioning against the use of this fluorescent label as a tag for following early stages of insulin aggregation.     

Discordance of databases designed for claims payment versus clinical information systems. Implications for outcomes research

OBJECTIVE: To determine the suitability of insurance claims information for use in clinical outcomes research in ischemic heart disease. DESIGN: Concordance study of two databases. SETTING: Tertiary care referral center. PATIENTS: A total of 12,937 consecutive patients hospitalized for cardiac catheterization for suspected ischemic heart disease between July 1985 and May 1990. INTERVENTIONS: Two-by-two tables were used to compute overall and kappa measures of agreement comparing clinical versus claims data for 12 important predictors of prognosis in patients with ischemic heart disease. MEASUREMENTS: Kappa statistics (agreement adjusted for chance agreement) were used to quantify agreement rates. RESULTS: Agreement rates between the clinical and claims databases ranged from 0.83 for the diagnosis of diabetes to 0.09 for the diagnosis of unstable angina (kappa values). Claims data failed to identify more than one half of the patients with prognostically important conditions, including mitral insufficiency, congestive heart failure, peripheral vascular disease, old myocardial infarction, hyperlipidemia, cerebrovascular disease, tobacco use, angina, and unstable angina, when compared with the clinical information system. CONCLUSIONS: Our results suggest that insurance claims data lack important diagnostic and prognostic information when compared with concurrently collected clinical data in the study of ischemic heart disease. Thus, insurance claims data are not as useful as clinical data for identifying clinically relevant patient groups and for adjusting for risk in outcome studies, such as analyses of hospital mortality.     

A transaction-based unified architecture for simulation and emulation

The availability of millions of transistors on a single chip has allowed the creation of complex on-chip systems. The functional verification of such systems has become a challenge. Simulation run times are increasing, and emulation is now a necessity. Creating separate verification environments for simulation and emulation slows the design cycle and it requires additional human efforts. This paper describes a layered architecture suitable for both simulation and emulation. The architecture uses transactions for communication and synchronization between the driving environment (DE) and the device under test (DUT). Transactions provide synchronization only as needed and cycle and event-based synchronization common in emulators. The result is more efficient development of the DE and 100% portability when moving from simulation to emulation. We give an overview of our layered architecture and describe its implementation. Our results show that, by using emulation, the register-transfer level (RTL) implementation of an industrial design can be verified in the same amount of time it takes to run a C-based simulation. We also show two orders of magnitude speeds up over simulations of C and RTL through a programming language interface     

The economic benefit of short-term forecasting for wind energy in the UK electricity market

In the UK market, the total price of renewable electricity is made up of the Renewables Obligation Certificate and the price achieved for the electricity. Accurate forecasting improves the price if electricity is traded via the power exchange. In order to understand the size of wind farm for which short-term forecasting becomes economically viable, we develop a model for wind energy. Simulations were carried out for 2003 electricity prices for different forecast accuracies and strategies. The results indicate that it is possible to increase the price obtained by around £5/MWh which is about 14% of the electricity price in 2003 and about 6% of the total price. We show that the economic benefit of using short-term forecasting is also dependant on the accuracy and cost of purchasing the forecast. As the amount of wind energy requiring integration into the grid increases, short-term forecasting becomes more important to both wind farm owners and the transmission/distribution operators.     

Generalized software components for reconfiguring hyper-redundant manipulators

An application of Operational Software Components for Advanced Robotics (OSCAR) - a generalized robotic software framework - for kinematic control of hyper-redundant, self-reconfigurable systems is presented. OSCAR includes generalized kinematics, dynamics, device interfacing, and criteria-based decision making. The developed application allows an operator to interactively reconfigure modular chains into parallel mechanisms, gait structures, and multiarm systems while maintaining full kinematic control of each chain. Examples using spatial systems with various geometries are presented with application pseudocode to illustrate high-level program development using OSCAR.     

Oxidative stress following traumatic brain injury in rats

BACKGROUND: Free radicals may be involved in the pathophysiology of traumatic brain injury (TBI) through oxidative damage of neurovascular structures. Endogenous antioxidants, such as ascorbate and alpha-tocopherol, may play a critical role in combating these oxidative reactions and their oxidized products can serve as an important index of oxidative stress. METHODS: We used electron spin resonance (ESR) spectroscopy and in vivo spin trapping (reaction of an organic compound with free radical species) to detect the possible generation of free radicals after TBI. Injury was inflicted by a weight drop technique over the head (5.7 kg-cm). Rats were intravenously infused with either 1 mL, 0.1 M of the spin trap, alpha-phenyl-N-tert-butyl nitrone (PBN), or an equivalent volume of saline immediately before TBI or sham-injury. Animals were divided into four groups: (1) Group I: PBN-infused sham-injured, (2) Group II: PBN-infused injured, (3) Group III: saline-infused sham-injured, and (4) Group IV: saline-infused injured. Additional groups of saline-infused uninjured, saline-infused, and PBN-infused injured animals were used for histopathology. Sixty minutes after TBI or sham-injury, rats were again anesthetized and decapitated. The brains were removed within 1 minute, homogenized, and extracted for lipids. The extracts were analyzed by ESR spectroscopy. Brain ascorbic acid (AA) concentration was determined spectrophotometrically, using the ascorbate oxidase assay. RESULTS: No PBN spin adduct signals (indicating trapped free radical species) were visible 60 minutes after TBI. All groups of rats showed an ascorbyl free radical signal. The ascorbyl signal intensity (AI) was, however, significantly higher in the injured rats, while the brain (AA) was significantly reduced. In addition, the ratio of AI/AA, which eliminates the effect of variable ascorbate concentrations in the brain, was also significantly higher in the injured animals. CONCLUSIONS: We conclude that 60 minutes following TBI there was a significantly increased level of oxidative stress in the brain. This may reflect formation of free radical species with subsequent interaction with ascorbate (antioxidant) during the 60 minute period. The lack of PBN spin adduct signals 1 hour after TBI may indicate that free radical generation is time dependent and might be detectable earlier or later than the 60 minute period.