Showing papers by "Ford Motor Company published in 1998"

Studies of the water-gas-shift reaction on ceria-supported Pt, Pd, and Rh: Implications for oxygen-storage properties

Abstract: Steady-state, water-gas-shift kinetics were measured on model, ceria-supported, Pd, Pt, and Rh catalysts and compared to rates obtained on alumina-supported catalysts. When ceria was calcined at low temperatures prior to addition of the precious metal, the specific rates were found to be identical for each of the metals, with an activation energy of 11 ± 1 kcal/mol and reaction orders of zero and one for CO and H 2 O respectively. For comparison, specific rates on Rh/alumina were at least two orders of magnitude lower. However, ceria structure strongly affected the results. When ceria was calcined to high temperatures to increase crystallite size, prior to the addition of Pd, specific rates were a factor of 50 lower at 515 K and the activation energy was found to be much higher, 21 ± 1 kcal/mol. By comparison with results from an earlier study of CO oxidation [17], we propose that water-gas shift on ceria-supported metals occurs primarily through a bifunctional mechanism in which CO adsorbed on the precious metal is oxidized by ceria, which in turn is oxidized by water. Deactivation of the catalyst following growth in the ceria crystallite size is due to the decreased reducibility of large ceria crystallites. The implications of these results for automotive, emission-control catalysts is discussed.

Major depression and stages of smoking. A longitudinal investigation.

Abstract: Background Epidemiologic studies have reported an association between major depression and smoking. This prospective study examines the role of depression in smoking progression and cessation, and the role of smoking in first-onset major depression. Methods Data are from a 5-year longitudinal epidemiologic study of 1007 young adults. Incidence and odds ratios (ORs) are based on the prospective data. Hazards ratios are based on the combined lifetime data and estimated in Cox proportional hazards models with time-dependent covariates. Results Based on the prospective data, history of major depression at baseline increased significantly the risk for progression to daily smoking (OR, 3.0; 95% confidence interval, 1.1-8.2), but did not decrease significantly smokers' rate of quitting (OR, 0.8; 95% confidence interval, 0.4-1.6). History of daily smoking at baseline increased significantly the risk for major depression (OR, 1.9; 95% confidence interval, 1.1-3.4). These estimates were reduced somewhat when history of early (ie, before age 15 years) conduct problems was controlled. Estimates based on lifetime data were consistent with these results. Conclusions The observed influences from major depression to subsequent daily smoking and smoking to major depression support the plausibility of shared etiologies. Separate causal mechanisms in each direction might also operate, including self-medication of depressed mood as a factor in smoking progression and neuropharmacologic effects of nicotine and other smoke substances on neurotransmitter systems linked to depression.

The Chemistry of Water on Alumina Surfaces: Reaction Dynamics from First Principles

Abstract: Aluminas and their surface chemistry play a vital role in many areas of modern technology. The behavior of adsorbed water is particularly important and poorly understood. Simulations of hydrated alpha-alumina (0001) surfaces with ab initio molecular dynamics elucidate many aspects of this problem, especially the complex dynamics of water dissociation and related surface reactions. At low water coverage, free energy profiles established that molecularly adsorbed water is metastable and dissociates readily, even in the absence of defects, by a kinetically preferred pathway. Observations at higher water coverage revealed rapid dissociation and unanticipated collective effects, including water-catalyzed dissociation and proton transfer reactions between adsorbed water and hydroxide. The results provide a consistent interpretation of the measured coverage dependence of water heats of adsorption, hydroxyl vibrational spectra, and other experiments.

Posttraumatic stress disorder and drug disorders: testing causal pathways.

Abstract: Background Although there is a high degree of comorbidity between posttraumatic stress disorder (PTSD) and drug use disorders, little is known about causal relationships between PTSD, exposure to traumatic events, and drug use disorders. Methods In a longitudinal study in southeast Michigan, 1007 adults aged 21 to 30 years were initially assessed in 1989 and were followed up 3 and 5 years later, in 1992 and 1994. Psychiatric disorders according to DSM-III-R criteria were measured by the National Institute of Mental Health Diagnostic Interview Schedule. To take into account temporal sequencing, the associations between PTSD, traumatic events, and drug use disorders were analyzed by using Cox proportional hazards models with time-dependent covariates. Results Posttraumatic stress disorder signaled an increased risk of drug abuse or dependence (hazards ratio, 4.5; 95% confidence interval, 2.6-7.6, adjusted for sex), whereas exposure to traumatic events in the absence of PTSD did not increase the risk of drug abuse or dependence. The risk for abuse or dependence was the highest for prescribed psychoactive drugs (hazards ratio, 13.0; 95% confidence interval, 5.3-32.0). There was no evidence that preexisting drug abuse or dependence increased the risk of subsequent exposure to traumatic events or the risk of PTSD after traumatic exposure. Conclusion The results suggest that drug abuse or dependence in persons with PTSD might be the inadvertent result of efforts to medicate symptoms, although the possibility of shared vulnerability to PTSD and drug use disorders cannot be ruled out.

Transcranial magnetic stimulation confirms hyperexcitability of occipital cortex in migraine

Abstract: Objectives: We hypothesized that the hyperexcitability of occipital cortex neurons may predispose migraine subjects to develop spreading depression, the putative basis of migraine with aura (MwA). To date there is no direct physiologic correlate confirming this in patients. Accordingly, we evaluated the differences in the threshold of occipital cortex excitation between MwA patients and normal controls (C) using transcranial magnetic stimulation(TMS). Methods: TMS was performed using the Cadwell MES 10 stimulator. A circular coil 9.5 cm in diameter was applied to the occipital scalp (7 cm above the inion). Stimulator intensity was increased in 10% increments until subjects reported visual phenomena or 100% intensity was reached. Stimulation intensity was then fine-tuned to determine the threshold at which phosphenes were just visualized. Results: Eleven MwA patients, mean age 37 ± 7 years, were compared with 11 C, mean age 37.7 ± 7 years. The difference in the proportion of subjects with phosphene generation between MwA patients and C was significant(MwA patients 100% versus C 27.3%, p = 0.001). The mean threshold level for MwA patients was 44.2 ± 8.6 versus 68.7 ± 3.1 for C( p = 0.0001). All threshold levels for MwA patients were lower than the lowest threshold for C; the MwA patient with the lowest threshold had an aura after stimulation. Conclusions: The threshold for excitability of occipital cortex is lower in MwA patients compared with C. This is a direct neurophysiologic correlate for clinical observations that have indicated hyperexcitability of the occipital cortex in migraineurs.

Novel, Ultraslow Inactivating Sodium Current in Human Ventricular Cardiomyocytes

Abstract: Background—Alterations in K+ channel expression and gating are thought to be the major cause of action potential remodeling in heart failure (HF). We previously reported the existence of a late Na+ current (INaL) in cardiomyocytes of dogs with chronic HF, which suggested the importance of the Na+ channel in this remodeling process. The present study examined whether this INaL exists in cardiomyocytes isolated from normal and failing human hearts. Methods and Results—A whole-cell patch-clamp technique was used to measure ion currents in cardiomyocytes isolated from the left ventricle of explanted hearts from 10 patients with end-stage HF and from 3 normal hearts. We found INaL was activated at a membrane potential of −60 mV with maximum density (0.34±0.05 pA/pF) at −30 mV in cardiomyocytes of both normal and failing hearts. The steady-state availability was sigmoidal, with an averaged midpoint potential of −94±2 mV and a slope factor of 6.9±0.1 mV. The current was reversibly blocked by the Na+ channel bloc...

Dynamic modeling and control of hybrid electric vehicle powertrain systems

Abstract: This paper describes the mathematical modeling, analysis, and simulation of a dynamic automatic manual layshaft transmission and dry clutch combination powertrain model, and corresponding coordinated control laws synthesized using a conventional SI ICE powerplant-alternator combination, a dry clutch and manual transmission/differential, variable field alternator, brakes, and complete vehicle longitudinal dynamics with tire-road interface characterization. The conventional power train model is validated using experimental test data confirming accurate emulation of dynamic components of the pre-hybridized vehicle. In addition, the development of dynamic series and parallel hybrid electric vehicle (HEV) powertrain models and corresponding coordinated control laws are described. A discussion of the key issues associated with coordinated control law development is provided. Simulations of the dynamic behavior of two types of series HEVs are shown.

Use of composite fingerprints to determine the provenance of the contemporary suspended sediment load transported by rivers

Abstract: Sediment fingerprinting appears to offer a valuable alternative to direct monitoring for elucidating the provenance of suspended sediment and the relative importance of spatial zones or subcatchments comprising larger ( >500 km 2 ) drainage basins. Against this background, a quantitative composite fingerprinting technique, incorporating both statistically verified multicomponent signatures and a multivariate sediment-mixing model, has been employed to determine the spatial origin of contemporary suspended sediment transported from the upper and middle reaches of the River Exe (601km 2 ) and River Severn (4325 km 2 ) basins, UK. Spatial origin is addressed in terms of the relative contribution from three distinct geological subareas constituting each study basin. The consistency of the composite fingerprinting approach is examined using the estimates for mean and seasonal variations in source area contributions and also a comparison between the results obtained for individual flood events and alternative lines of evidence provided by flood travel times and the spatial distribution of precipitation. It is argued that fingerprinting estimates for sediment provenance are consistent with existing information on suspended sediment yields from different subcatchments within the study basins, although in the Severn, the role of storage and remobilization in producing signature ‘averaging’ may complicate comparison of the fingerprinting data with typical floodwater routing times. Validation represents the greatest problem for the cost‐benefit of fingerprinting and scope still exists for further refinement of the procedures involved. © 1998 John Wiley & Sons, Ltd.

Innovation overview and future challenges

Abstract: This article reviews the changing understanding of the word “innovation”. It contains a summary of the critical criteria for innovation to take place, based upon a study of previous researchers’ work in this area. Explores the way in which developments in materials and other technologies have acted to allow innovation to take place. It is argued that materials development is a constant source of new opportunity, and that other advances periodically occur that also support successful change. Micro‐electronics is cited as a technology that has become a major enabler to innovation. The pressures on modern industry to achieve improvements to the quality, cost and development time of products are reviewed, and it is postulated that the response to these pressures encourages conservatism in new designs and thus acts to suppress innovation.

Epidemiology of alcohol and medication as aids to sleep in early adulthood

Abstract: Study objectives In a representative sample of adults 18-45 years of age, this study addressed three questions about the use of sleep aids in the general population: (1) what are the past-year prevalences of the use of alcohol, over-the-counter medication and prescription medication to facilitate sleep? (2) among those who use these substances for sleep problems, what are the patterns of use? and (3) are there social factors, independent of sleep characteristics, that increase the likelihood of alcohol and medication use to aid sleep? Design The 1996 Detroit Area Survey was a random-digit-dial, computer-assisted survey of a representative sample of 2,181 adults ages 18-45 in the Detroit primary metropolitan statistical area. Eligible household response rate was 86.8%. Results In the general population, use of alcohol and medication as sleep aids in the past year was found to be fairly common: 13% used alcohol, 18% used medications and 5% used both. The prevalence of any substance use to aid sleep was 26%. The duration of use was short for the majority of users, less than 1 week. However, duration of use was greater for the majority of those using prescription sleep aids. A substantial minority of users report regular use lasting longer than 1 month: 15%, 9%, and 36% for alcohol, OTC medications, and prescription medications, respectively. Both sociodemographic and sleep characteristics were associated with alcohol and medication use to aid sleep. Difficulty falling asleep was the factor most strongly associated with use of substances to improve sleep. Sex, race/ethnicity, work shift, marital status and education were also significantly associated with one or more types of sleep aid use adjusting for difficulty falling asleep.

Post-traumatic stress disorder and somatization symptoms: a prospective study.

Abstract: The objective of this study is to determine whether persons with a history of post-traumatic stress disorder (PTSD) are at increased risk for somatization symptoms. Using the NIMH Diagnostic Interview Schedule, 1007 21-30-year-old members of a large health maintenance organization in south-east Michigan were interviewed initially in 1989, with follow-up interviews conducted in 1992 and 1994. Prevalence of somatization syndrome and number of somatization symptoms in the 5-year follow-up period were compared in relation to PTSD status at baseline, using logistic regression. History of PTSD was associated with significantly more symptoms in each of the somatic symptom groups, except pain. In addition, persons with PTSD were more likely to report each of the symptoms of somatization, compared to those with other psychiatric disorders. Prospectively, baseline history of PTSD signaled an increased risk of pain (OR = 2.1) and conversion symptoms (OR = 2.3) in the follow-up interval, relative to those with no disorder. PTSD increased the risk of somatization symptoms beyond that expected by the presence of comorbid psychiatric disorders. The excess of somatization symptoms in persons with history of PTSD might be attributable to PTSD per se, or to the greater severity of the associated comorbidity, compared to persons with disorders other than PTSD.

Effect of SiC volume fraction and particle size on the fatigue resistance of a 2080 Al/SiCp composite

Abstract: The effect of SiC volume fraction and particle size on the fatigue behavior of 2080 Al was investigated. Matrix microstructure in the composite and the unreinforced alloy was held relatively constant by the introduction of a deformation stage prior to aging. It was found that increasing volume fraction and decreasing particle size resulted in an increase in fatigue resistance. Mechanisms responsible for this behavior are described in terms of load transfer from the matrix to the high stiffness reinforcement, increasing obstacles for dislocation motion in the form of S’ precipitates, and the decrease in strain localization with decreasing reinforcement interparticle spacing as a result of reduced particle size. Microplasticity was also observed in the composite, in the form of stress-strain hysteresis loops, and is related to stress concentrations at the poles of the reinforcement. Finally, intermetallic inclusions in the matrix acted as fatigue crack initiation sites. The effect of inclusion size and location on fatigue life of the composites is discussed.

Neuronal Damage and Plasticity Identified by Microtubule-Associated Protein 2, Growth-Associated Protein 43, and Cyclin D1 Immunoreactivity After Focal Cerebral Ischemia in Rats

Abstract: Background and Purpose —An objective of therapeutic intervention after cerebral ischemia is to promote improved functional outcome. Improved outcome may be associated with a reduction of the volume of cerebral infarction and the promotion of cerebral plasticity. In the developing brain, neuronal growth is concomitant with expression of particular proteins, including microtubule-associated protein 2 (MAP-2), growth-associated protein 43 (GAP-43), and cyclin D1. In the present study we measured the expression of select proteins associated with neurite damage and plasticity (MAP-2 and GAP-43) as well as cell cycle (cyclin D1) after induction of focal cerebral ischemia in the rat. Methods —Brains from rats (n=28) subjected to 2 hours of middle cerebral artery occlusion and 6 hours, 12 hours, and 2, 7, 14, 21, and 28 days (n=4 per time point) of reperfusion and control sham-operated (n=3) and normal (n=2) rats were processed by immunohistochemistry with antibodies raised against MAP-2, GAP-43, and cyclin D1. Double staining of these proteins for cellular colocalization was also performed. Results —Loss of immunoreactivity of both MAP-2 and GAP-43 was observed in most damaged neurons in the ischemic core. In contrast, MAP-2, GAP-43, and cyclin D1 were selectively increased in morphologically intact or altered neurons localized to the ischemic core at an early stage (eg, 6 hours) of reperfusion and in the boundary zone to the ischemic core (penumbra) during longer reperfusion times. Conclusions —The selective expressions of the neuronal structural proteins (MAP-2 in dendrites and GAP-43 in axons) and the cyclin D1 cell cycle protein in neurons observed in the boundary zone to the ischemic core are suggestive of compensatory and repair mechanisms in ischemia-damaged neurons after transient focal cerebral ischemia.

Laboratory and theoretical study of the oxy radicals in the OH- and Cl-initiated oxidation of ethene

Abstract: The products of the OH-initiated oxidation mechanism of ethene have been studied as a function of temperature (between 250 and 325 K) in an environmental chamber, using Fourier transform infrared spectroscopy for end product analysis. The oxidation proceeds via formation of a peroxy radical, HOCH2CH2O2. Reaction of this peroxy radical with NO is exothermic and produces chemically activated HOCH2CH2O radicals, of which about 25% decompose to CH2OH and CH2O on a time scale that is rapid compared to collisions, independent of temperature. The remainder of the HOCH2CH2O radicals are thermalized and undergo competition between decomposition, HOCH2CH2O → CH2OH + CH2O (6), and reaction with O2, HOCH2CH2O + O2 → HOCH2CHO + HO2 (7). The rate constant ratio, k6/k7, for the thermalized radicals was found to be (2.0 ± 0.2) × 1025 exp[−(4200 ± 600)/T] molecule cm-3 over the temperature range 250−325 K. With the assumption of an activation energy of 1−2 kcal mol-1 for reaction 7, the barrier to decomposition of the HOC...

On the applicability of product variety design concepts to automotive platform commonality

Abstract: The issue of moving from a mass production operating mode to mass customization, or even limited customization, has many companies struggling to reorganize their product architectures. Enabling the production of several related products for different market segments, from a common base, is the focus of the product variety design research area. In this paper, the applicability of product variety design concepts to the design of automotive platforms is explored. Many automotive companies are reducing the number of platforms they utilize across their entire range of cars and trucks in an attempt to reduce development times and costs. To what extent can research on product variety design apply to the problem of platform commonization? This question is explored by comparing product variety design concepts (standardization, modularity, mutability, etc.) to platform structures and requirements. After assessing the applicability of these concepts, a platform representation and methods for measuring platform commonality are proposed that incorporate key characteristics of these concepts. An application to two platforms is included. Although preliminary, this work has led to insight as to why automotive platform commonization is difficult and how product design variety research can potentially aid commonization. The findings are potentially applicable to product platforms in general.