Teaching Macroeconomics with GAMS

Our general goal in this paper is to show how to implement in GAMS standard deterministic nonlinear macro models, and stochastic linear macro models with rational expectations. We will also present basic concepts on solution methods and policy analysis for these kinds of models. As a practical illustration, we will use some well known teaching and experimental models in the macroeconomic literature.     

Introduction to the Works of Rodney C. Wingrove: Engineering Approaches to Macroeconomic Modeling

A continuous-time control model was formulated and fitted to macroeconomic data by an expert control engineer who worked at NASA-AMES in the 1980s, Rodney C. Wingrove. Two articles were prepared and made available to the aerospace industry at that time, however the authors feel that wider distribution of his study posthumously is warranted at this time. This introduction to the two Wingrove articles that follow provides background information on the technologies Wingrove was working with, as well as subsequent developments in both macroeconomic and engineering modeling and analysis technology. Our purpose is to stimulate further research along the same lines which can potentially lead to structural and/or policy rule improvements that can prevent the extremely turbulent abberations that have been seen in recent years, and promote steady growth with low inflation and low unemployment in a sustainable way. Of particular concern is the exploding national debt problem.     

Operando infrared spectroscopy of the fuel cell membrane electrode assembly Nafion–platinum interface

The Nafion–Pt interfaces in membrane electrode assemblies of operating fuel cells were studied by operando infrared spectroscopy. The potential dependence of atop adsorbed CO peak frequencies were measured over the potential range of 0–600 mV (vs. NHE) at 60 °C. Complex Stark tuning of peak frequencies arise from a combination of potential dependent coverage effects, and changes in the extent of back-donation from the metal d-band to the renormalized 2π^∗ MO of CO_ads. The Nafion–Pt interface was studied at higher potentials (initiating at open circuit) by examining platinum reflectivity as a function of electrode potential. The oxygen reduction onset-current is coincident with the observance of a 2% step-increase in Pt reflectivity and emergence of Nafion–Pt interface spectra.     

Cessation of polyunsaturated fatty acid formation in four selected filamentous fungi when grown on plant oils

Four fungi,Conidiobolus nanodes, Entomophthora exitalis, Mortierella isabellina, andMucor circinelloides, were grown on various oils (triolein, sesame, safflower, linseed, and oil fromM. isabellina) and produced lipids in which the fatty acids were predominantly the same as those of the original staring substrate. Only in the first two cases was there evidence of a small amount of chain elongation and of fatty acid desaturation taking place. The extent of this was only about 10% of that seen in glucose-grown cells. The apparent repression of the fatty acid desaturases and elongases was not reversed by growing cells on glucose and oils as mixed substrates—the fatty acid profiles were the same as when the fungi had grown in oils alone. Neither was the cessation of polyunsaturated fatty acid synthesis due to the presence of nonoil components (NOC) in the oil. Only the NOC from sesame oil affected one single conversion, that of 20∶3n-3 to 20∶4n–6. We conclude that fatty acid desaturase and elongase systems are repressed either partially or completely in a filamentous fungi grown on triacylglycerol oils.     

Effects of substitutions in the binding surface of an antibody on antigen affinity

The interactions between the Fab and single-chain Fv (scFv) fragments of an antibody (NC10) and its antigen, influenza virus neuraminidase, were analysed in the crystal structures of the Fab-neuraminidase and scFv-neuraminidase complexes. To investigate the contribution to binding made by cavities, salt links and hydrogen bonds in the antibody- antigen interface, 14 single amino acid replacements were made at six contact residues in the scFv fragment by site-directed mutagenesis. The binding affinity of each mutant scFv antibody for neuraminidase was determined with a BIAcore optical biosensor. Four of the mutations resulted in large changes in the free energy of binding to neuraminidase (deltadeltaG > 1 kcal/mol) and together may account for approximately 70% of the free energy of binding. Hence these data support the theory that a small number of residues form the 'functional epitope' and are most important for binding of NC10 to neuraminidase. The salt link between antibody residue (Asp)H56 and (Lys)N432 from neuraminidase was demonstrated to be important for affinity, since substitution of (Asp)H56 with Asn caused a large reduction in the free energy of binding (deltadeltaG = +2.8 kcal/mol). Hydrogen bonds provided by (Tyr)L32 and (Asp)H56 were also important for binding: mutation of (Tyr)L32 to Phe resulted in a significant reduction in binding affinity (deltadeltaG = +1.7 kcal/mol). Disruption of hydrophobic interactions (van der Waals contacts) led to significant reductions in affinity also ((Tyr)H99 to Ala, deltadeltaG = +1.5 kcal/mol; (Leu)L94 to Ala, deltadeltaG > +3.0 kcal/mol). An attempt to increase binding affinity by filling a cavity in the interface with a larger antibody side chain was unsuccessful, as the free energy gained by new antibody-antigen interactions did not compensate for the removal of cavity-bound water molecules.      

The UCSC Kestrel parallel processor

The architectural landscape of high-performance computing stretches from superscalar uniprocessor to explicitly parallel systems, to dedicated hardware implementations of algorithms. Single-purpose hardware can achieve the highest performance and uniprocessors can be the most programmable. Between these extremes, programmable and reconfigurable architectures provide a wide range of choice in flexibility, programmability, computational density, and performance. The UCSC Kestrel parallel processor strives to attain single-purpose performance while maintaining user programmability. Kestrel is a single-instruction stream, multiple-data stream (SIMD) parallel processor with a 512-element linear array of 8-bit processing elements. The system design focuses on efficient high-throughput DNA and protein sequence analysis, but its programmability enables high performance on computational chemistry, image processing, machine learning, and other applications. The Kestrel system has had unexpected longevity in its utility due to a careful design and analysis process. Experience with the system leads to the conclusion that programmable SIMD architectures can excel in both programmability and performance. This work presents the architecture, implementation, applications, and observations of the Kestrel project at the University of California at Santa Cruz.     

Near miss and minor injury information--can it be used to plan and evaluate injury prevention programmes?

AIM: To assess the usefulness of collecting information on near miss and minor injuries for use in planning and evaluating injury prevention programmes for children aged under 5 years in the home environment. METHOD: The research was set within the context of a controlled intervention study based in 36 general practices across Nottingham. All parents of children aged between 3 and 12 months who had completed the intervention study questionnaire (n = 1594) were used as the sampling frame for the diary study. A diary, developed specifically for the main intervention study, was administered to a systematically assigned sample of 434 parents. Information provided by the Home Accident Surveillance System on 252 randomly selected children, of the same age and sex, who had attended an accident and emergency department, was used to compare the circumstances surrounding near miss and minor injuries with those of medically attended injuries. The children whose parents had completed a diary were followed over a two year time period. The children who had had a medically attended injury were identified from a search of the child's general practice records and the Queens Medical Centre accident and emergency records. The definition of a near miss used in the study was: A near miss incident is something your child does or that happened to your child which could have resulted in him/her being hurt, but fortunately it did not. RESULTS: Overall two hundred and thirty one (53%) diaries were completed and returned. Three hundred and fifty incidents were recorded of which 207 were near misses and 143 minor injuries. The circumstances surrounding near miss and minor injuries, although not identical when compared to medically attended injuries, were very similar. The relationship between the occurrence of near miss, minor injuries and future medically attended injuries appeared weak, for all categories the negative predictive value was higher than the positive predictive value. CONCLUSION: Although the circumstances surrounding all the incident categories were similar, the numbers were too small to see whether specific injury mechanisms predict future injuries of the same type. It appeared that near miss and minor injuries are of limited use in predicting medically attended injuries, however this hypothesis needs to be tested on a much larger sample.     

U73122 and U73343 inhibit receptor-mediated phospholipase D activation downstream of phospholipase C in CHO cells

We investigated the effects of nitric oxide (NO) donors, S-nitroso-N-acetylpenicillamine and sodium nitroprusside on basal and K+-evoked release of [3H]noradrenaline from superfused synaptosomes from the rat cerebral cortex. Both substances produced concentration-dependent increases in the release of the labeled transmitter under basal and depolarized conditions. The effects of the donors on basal release were Ca2+-independent but were not inhibited by the carrier-uptake blocker, desipramine; the effects were abolished by hemoglobin (an NO scavenger). Thirty-five minutes after stimulation with sodium nitroprusside, the synaptosomes were still responsive to KCl stimulation, indicating that the donor's effects were not caused by damage to the synaptosome membrane. The cGMP analogue, 8-bromo-cGMP, had no effect on basal release, and the enhanced release produced by sodium nitroprusside was not inhibited by the specific inhibitor of soluble guanylate cyclase, 1H-[1,2,4]oxadiazolo[4,3-alpha]quinoxalin-1-one, indicating that NO's effects on basal release of the neurotransmitter are guanylate cyclase-independent. Both of the NO donors had more marked effects on release of [3H]noradrenaline during K+-stimulated depolarization. The NO-mediated increase in this case was partially antagonized by 10 microM LH-[1,2,4]oxadiazolo[4,3-alpha]quinoxalin-1-one, and 8-Br-cGMP was also capable of producing concentration-dependent increases in the K+-stimulated release of the transmitter. These findings indicate that the effects of the NO donors on [3H]noradrenaline release during depolarization are partially mediated by the activation of guanylate cyclase.     

The t(5;17) variant of acute promyelocytic leukemia expresses a nucleophosmin-retinoic acid receptor fusion

The classical action of the hormone 1,25-dihydroxyvitamin D3 (VD) is the regulation of calcium metabolism. In contrast, the peptide hormone atrial natriuretic factor (ANF) is one of the few known nonclassical VD responding genes. We screened the promoter of the rat ANF gene and identified a typical VD receptor (VDR) binding site formed by a direct repeat of two hexameric core binding motifs spaced by three nucleotides, between positions -907 and -891. Like most of the DR3-type VD response elements this sequence is bound with high affinity (Kd = 0.53 nM) by a heterodimer formed by VDR and retinoid X receptor. In a heterologous promoter context one copy of this sequence mediated an about fourfold gene activation by VD and a half-maximal activation (EC50) value of 0.48 nM VD. This characterizes the identified sequence as one of the most potent VD response elements.