The Collapse of the International Tin Agreement

SUMMARY On 24 October 1985 the International Tin Council announced that it could not pay its debts to banks and metal brokers. The crisis ended with the ITC facing legal actions after defaulting on almost £900 mn. Its problems have cast a shadow over other commodity agreements and the chances of UNCTAD's Integrated Programme. The collapse shows that commodity agreements must price realistically and control a high proportion of production if they are to survive. The conclusion is that the volatility of modern capital flows and diversification of developing economies make commodity agreements more difficult to maintain and perhaps less important. RESUME L'Effondrement de l'Accord international sur le Fer Le 24 Octobre 1985, le Conseil International du Fer annonça qu'il ne pouvait pas payer sa dette aux banques et aux agents de change. La crise se termina par le ITC (Conseil International du Fer) se trouvant à faire face à une action en justice pour le non?paiement d'une dette de £900mn. Ces problèmes ont assombri les accords passés sur d'autres produits et les chances du Programme Intégré de l'UNCTAD. L'effondrement montre que les accords sur la production doivent établir des prix de manière rèalistique et contrôler une grande proportion de la production s'ils veulent survivre. En conclusion, l'inconstance du flux du capital moderne et la diversification des économies en voie de développement rend les accords sur la production difficiles à maintenir et peut?être diminue leur importance. RESUMEN El colapso del convenio internacional del estaño El 24 de octubre de 1985 el Consejo Internacional del Estaño (CIE), anunció que no podia pagar sus deudas a los corredores bancarios y metaleros. La crisis terminó con el CIE enfrentando acciones judiciales después de no pagar casi 900 millones de libras esterlinas. Sus problemas han creado una sombra sobre otros convenios de mercancias y sobre el futuro del Programa Integrado de la UNCTAD. El colapso demuestra que para sobrevivir, los convenios de mercancías deben ser realistas en los precios y controlar una alta proporción de la producción. Se concluye que la volatilidad de los flujos del capital moderno y la diversificación de las economías en desarrollo hacen que los convenios de mercancías sean más dificiles de mantener y que quizás se tornen menos importantes

Improvement of the Gait Analysis Process

This report describes the complete design and testing of a methodology for the creation of a force sensing device that can be used to provide clinically significant data to aid a prosthetist in the static alignment of a transtibial prosthesis fitting. Thin-film force transducers form the basis for the prototype force sensing module that is integrated into a prosthetic leg for the testing and future alignment fittings. This physical force sensing device was used along with a computer simulation of the limb and module to collect force measurement results, both positionally relative and absolute. The experimental data collected were analyzed using Analysis of Variance, effects plots and prediction equations. The statistical analysis helped to evaluate the feasibility of using similar data and methods for producing a system capable of predicting and validating changes in force distribution relationship, the accuracy of the force sensing module could be improved. The recommendations for future revisions of this design include using more accurate force sensors and conducting more replications of the physical testing

Computational Benchmarking in Biomimetic Nickel, Copper, and Iron Complexes

Sophisticated catalytically active sites of metalloenzymes provide inspiration to synthetic chemists, as the metal coordination environments are often atypical to those found on the chemist's benchtop. Furthermore, metal-ligand cooperativity using earthabundant metals is anticipated to eventually supplant noble metals, currently used in industrial catalysis. Despite progress in synthesis of small molecule active site models, reproduction of the enzymatic function is rarely observed. However, differences that might define catalytic efficiency of enzymes can be addressed by theory. Density functional theory, or DFT, has been developed as an in silico tool to complement and interpret crystallographic and spectroscopic results or to make predictions in the absence of experimental data. In this dissertation, such techniques serve to elucidate the observed reactivity or electronic character of both nickel and copper bound in square planar N₂S₂ ligand fields, and of {Fe(NO)₂} units, respectively. Nickel and copper complexes in tetraanionic N₂S₂⁴⁻ ligand environments were investigated with respect to change of metal, to modification of ligand environment, and to response in reactivity of thiolate sulfur atoms. From the DFT calculations and consistent with experimental observations, it was discovered that binding of a nucleophile at one thiolate sulfur effectively decreases reactivity of the second sulfur, and nucleophilic binding at both sulfurs serves to deactivate the complex toward further thiolate reactivity. Additionally, despite both Cu and Ni binding comfortably in the N₂S₂⁴⁻ coordination sphere, the former displays increased ionicity versus the latter, demonstrated by electrostatic potential mapping. A methodology for accurate modeling of geometry and vibrational frequencies of complexes containing a {Fe(NO)₂} unit was determined from the results of a test set of complexes using a matrix of functionals and basis sets. Utilizing the optimum performer, the BP86 functional and a mixed SDD ECP basis set on iron and 6-311++G(d,p) on other atoms, a series of iron dinitrosyl complexes containing diverse ancillary ligands spanning the spectrochemical series was subsequently investigated. The electrochemical potentials of the pairs of "oxidized" and "reduced" DNIC complexes were evaluated for values occurring in the biological regime. Furthermore, as the {Fe(NO)₂} unit is capable of coordination in interesting yet dissimilar geometric motifs, bimetallic, tetrameric, and adamantane-like DNIC complexes have been investigated with our DFT methodology

A predictive coding model of the N400

The N400 event-related component has been widely used to investigate the neural mechanisms underlying real-time language comprehension. However, despite decades of research, there is still no unifying theory that can explain both its temporal dynamics and functional properties. In this work, we show that predictive coding – a biologically plausible algorithm for approximating Bayesian inference – offers a promising framework for characterizing the N400. Using an implemented predictive coding computational model, we demonstrate how the N400 can be formalized as the lexico-semantic prediction error produced as the brain infers meaning from the linguistic form of incoming words. We show that the magnitude of lexico-semantic prediction error mirrors the functional sensitivity of the N400 to various lexical variables, priming, contextual effects, as well as their higher-order interactions. We further show that the dynamics of the predictive coding algorithm provides a natural explanation for the temporal dynamics of the N400, and a biologically plausible link to neural activity. Together, these findings directly situate the N400 within the broader context of predictive coding research. More generally, they raise the possibility that the brain may use the same computational mechanism for inference across linguistic and non-linguistic domains.</p

The Effect of a High Fat Meal on Cerebral Vascular Function

It is well known that a single high fat meal (HFM) causes a robust and transient elevation in serum triglycerides (TG). This elevation in serum TG is a primary contributor to the post-prandial attenuation of peripheral vascular endothelial function, as assessed by flow-mediated dilation in the brachial artery. Whether a similar impairment in vascular reactivity can be observed in the cerebral circulation remains unknown, and was the focus of this investigation. PURPOSE: To test the hypothesis that cerebral vascular function is impaired following a HFM. METHODS: End-tidal carbon dioxide partial pressure (PETCO2), middle cerebral artery blood velocity (MCAVmean), calculated cerebral vascular conductance index (CVCI; MCAVmean/mean arterial pressure) and cerebral vasodilator response to rebreathing induced hypercapnia (% increase in CVC from baseline at common maximal ΔPETCO2) were assessed in 6 healthy young men (27 ±5 years). Measures were assessed during fasted baseline and again at 2 and 4 h post meal consumption (HFM day) or at a similar time point in the fasted state (TC day). The two visits were separated by 2-7 days and were conducted in a randomized order. Blood lipids were assessed at baseline and at the 2 h time point into each respective condition. RESULTS: As expected, consumption of the HFM significantly elevated serum TG concentrations relative to TC at 2 h (HFM: 101±38 to 169±77mg/dl, TC: 107±32 to 92±31mg/dl, P=0.007). However, the HFM had no effect of cerebral vasodilator capacity during rebreathing induced hypercapnia. The maximal increase in %CVC achieved at the highest common ΔPETCO2 during all conditions within each subject was unchanged during 2hr and 4hr post HFM or TC (condition x time interaction: P=0.96). Similarly, the slope of the change in %CVC per change in ΔPETCO2 was unaffected by HFM across time (P=0.49). CONCLUSION: Contrary to our hypothesis, and unlike the peripheral vasculature, our preliminary data suggest that the cerebral circulation appears to be protected from the acute negative effects of a high fat meal

What Is Special about Aromatic-Aromatic Interactions? Significant Attraction at Large Horizontal Displacement

High-level ab initio calculations show that the most stable stacking for benzene-cyclohexane is 17% stronger than that for benzene-benzene. However, as these systems are displaced horizontally the benzene-benzene attraction retains its strength. At a displacement of 5.0 Å, the benzene-benzene attraction is still ∼70% of its maximum strength, while benzene-cyclohexane attraction has fallen to ∼40% of its maximum strength. Alternatively, the radius of attraction (>2.0 kcal/mol) for benzene-benzene is 250% larger than that for benzene-cyclohexane. Thus, at relatively large distances aromatic rings can recognize each other, a phenomenon that helps explain their importance in protein folding and supramolecular structures

Supplementary data for the article: Ninković, D. B.; Vojislavljević-Vasilev, D. Z.; Medaković, V. B.; Hall, M. B.; Brothers, E. N.; Zarić, S. D. Aliphatic-Aromatic Stacking Interactions in Cyclohexane-Benzene Are Stronger than Aromatic-Aromatic Interaction in the Benzene Dimer. Physical Chemistry Chemical Physics 2016, 18 (37), 25791–25795. https://doi.org/10.1039/c6cp03734h

Supplementary material for: [https://doi.org/10.1039/c6cp03734h]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2328]Related to accepted version: [http://cherry.chem.bg.ac.rs/handle/123456789/3324

Supplementary data for the article: Guan, J.; Wriglesworth, A.; Sun, X. Z.; Brothers, E. N.; Zarić, S. D.; Evans, M. E.; Jones, W. D.; Towrie, M.; Hall, M. B.; George, M. W. Probing the Carbon-Hydrogen Activation of Alkanes Following Photolysis of Tp′Rh(CNR)(Carbodiimide): A Computational and Time-Resolved Infrared Spectroscopic Study. Journal of the American Chemical Society 2018, 140 (5), 1842–1854. https://doi.org/10.1021/jacs.7b12152

Peer-reviewed manuscript: [http://cherry.chem.bg.ac.rs/handle/123456789/2893]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2091]Related to accepted version: [http://cherry.chem.bg.ac.rs/handle/123456789/2893

Supplementary data for article: Stanković, I. M.; Božinovski, D. M.; Brothers, E. N.; Belić, M. R.; Hall, M. B.; Zarić, S. D. Interactions of Aromatic Residues in Amyloids: A Survey of Protein Data Bank Crystallographic Data. Crystal Growth and Design 2017, 17 (12), 6353–6362. https://doi.org/10.1021/acs.cgd.7b01035

Supporting information for: [https://doi.org/10.1021/acs.cgd.7b01035]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2566

Artificial recharge in the Las Vegas Valley: An Operational history

Artificially recharging the Las Vegas Valley (Valley) ground-water system with treated Colorado River water is one water resource management option employed by the Las Vegas Valley Water District (District) to help meet future long-term and short-term peak water demands. The District began operation of an artificial ground-water recharge program in 1988 in order to bank water for future use and to slow declining water levels. Artificial recharge occurs in the winter months, typically from October to May, when there is excess capacity in the Southern Nevada Water System (SNWS), currently a 400 Million Gallon per Day (MGD) treatment and transmission system. Treated Colorado River water is recharged into the principal aquifer through the District\u27s existing distribution system, to a network of production wells or dual -use wells for both recharge and production. The water is then stored until recovered from the wells, during the high demand summer months. The water recovered is injected Colorado River water, however, this water is accounted against the District\u27s groundwater rights. Credits in the artificial recharge account accrue until needed to cover pumpage in excess of permitted ground-water rights. Wells used in the program were drilled and constructed in a variety of ways, and have responded differently to artificial recharge operations. The majority of the wells now used for artificial recharge and production were completed prior to 1980, using the cable-tool drilling method, perforated in place and naturally developed. Other wells were installed using the reverse-circulation drilling method with filter packs. The District commenced drilling dedicated injection wells in 1993, to address operational concerns observed in some of the production wells. Several types of installation and drilling methods have been used to optimize injection. The types of drilling methods used for the injection wells include, reverse circulation, air-foam, cable tool and dual-rotary. In 1988, two dual-use wells where used for production and artificial recharge, injecting an annual total of 1,153 acre feet of water. Since 1988 the artificial recharge program has expanded, using up to 40 wells with eight dedicated injection wells. Total water banked for future use, as of January 1, 1997 is 114,126 acre feet of water. Static water levels in the principal aquifer have risen from 10 to 40 feet in the main area of artificial recharge. Water levels in other areas of the Valley also show increases, indicating that the rise is not isolated, but is occurring throughout the principal aquifer. The artificial recharge program is currently expanding to utilize 31 dual use and 19 injection wells, for a potential capacity of 62,000 gallons per minute of injection or 45,000 acre feet per year of recharge by the fall of 1999