Credit ratings and government bonds evidence before, during and after the european debt crisis

Neste projeto, investigamos se as agências de rating e as taxas de juro de longo prazo da dívida soberana tiveram uma influência recíproca antes, durante e após a crise da dívida soberana Europeia. Esta análise é realizada, estimando a relação existente entre os ratings da dívida soberana ou taxas de juro e factores macroeconomicos e estruturais, através de uma diferente aplicação de metodologias utilizadas para este efeito. Os resultados obtidos demonstram que, no período da crise soberana, os ratings e as taxas de juros tiveram um mútuo impacto, sugerindo que as descidas dos ratings podem ter conduzido a profecias auto-realizáveis, levando países relativamente estáveis a um eventual incumprimento

Long-term effect of carbodiimide on dentin matrix and resin-dentin bonds

Objectives: To characterize the interaction of 1-Ethyl-3-[3-dimethylaminopropyl] carbodiimide Hydrochloride (EDC) with dentin matrix and its effect on the resin-dentin bond. Methods: Changes to the stiffness of demineralized dentin fragments treated with EDC/N-hydroxysuccinimide (NHS) in different solutions were evaluated at different time points. The resistance against enzymatic degradation was indirectly evaluated by ultimate tensile strength (UTS) test of demineralized dentin treated or not with EDC/NHS and subjected to collagenase digestion. Short- and long-term evaluations of the strength of resin-dentin interfaces treated with EDC/NHS for 1 h were performed using microtensile bond strength (mu TBS) test. All data (MPa) were individually analyzed using ANOVA and Tukey HSD tests (alpha = 0.05). Results: The different exposure times significantly increased the stiffness of dentin (p < 0.0001, control-5.15 and EDC/NHS-29.50), while no differences were observed among the different solutions of EDC/NHS (p = 0.063). Collagenase challenge did not affect the UTS values of EDC/NHS group (6.08) (p > 0.05), while complete degradation was observed for the control group (p = 0.0008, control-20.84 and EDC/NHS-43.15). EDC/NHS treatment did not significantly increase resin-dentin mu TBS, but the values remained stable after 12 months water storage (p < 0.05). Conclusions: Biomimetic use of EDC/NHS to induce exogenous collagen cross-links resulted in increased mechanical properties and stability of dentin matrix and dentin-resin interfaces. (C) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 94B: 250-255, 2010.

Chlorhexidine increases the longevity of in vivo resin-dentin bonds

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Exposed collagen in aged resin-dentin bonds produced on sound and caries-affected dentin in the presence of chlorhexidine

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of acid etching time on the degradation of resin-dentin bonds in primary teeth

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

C-H center dot center dot center dot O and N-H center dot center dot center dot O hydrogen bonds in liquid amides investigated by Monte Carlo simulation

Monte Carlo simulations of liquid formamide, N-methylformamide (MF), and N,N-dimethylformamide (DMF) have been performed in the isothermal and isobaric ensemble at 298 K and 1 atm, aiming to investigate the C-H ... O and N-H ... O hydrogen bonds. The interaction energy was calculated using the classical 6-12 Lennard-Jones pairwise potential plus a Coulomb term on a rigid six-site molecular model with the potential parameters being optimized in this work. Theoretical values obtained for heat of vaporization and liquid densities are in good agreement with the experimental data. The radial distribution function [RDF, g(r)] obtained compare well with R-X diffraction data available. The RDF and molecular mechanics (MM2) minimization show that the C-H ... O interaction has a significant role in the structure of the three liquids. These results are supported by ab initio calculations. This Interaction is particularly important in the structure of MF. The intensity of the N-H ... O hydrogen bond is greater in the MF than formamide. This could explain some anomalous properties verified in MF. (C) 1997 John Wiley & Sons, Inc.

Thermal behaviour of polymetallic metal carbonyls with Fe-Fe, Fe-Hg and Hg-Hg bonds containing Lewis bases.

The thermal behaviour of polymetallic metal carbonyls containing Fe-Fe, Fe-Hg and Hg-Hg bonds and Lewis bases, such as [Fe-3(CO)(8)(L)(2)] (L = 1,10-phenantroline,2,2'-bipyridine), [Fe(CO)(4)(HgCl)(2)] and [Fe(CO)(4)(HgCl)(2)(L)(2)] (L = 1,10-phenantroline,2-quinolinethiol), have been investigated by thermal analysis (TG), Thermal studies give evidence that the thermal decomposition mechanisms and starting temperatures are strongly influenced by the Lewis bases. The thermal decompositions under synthetic air yielded, in all cases, the final solid product Fe2O3 which presence was confirmed by X-ray powder diffraction technique.

C - H ⋯ 0 and N - H ⋯ 0 hydrogen bonds in liquid amides investigated by monte carlo simulation

Monte Carlo simulations of liquid formamide, N-methylformamide (MF), and N, N-dimethytformamide (DMF) have been performed in the isothermal and isobaric ensemble at 298 K and 1 atm, aiming to investigate the C-H ⋯ O and N-H ⋯ O hydrogen bonds. The interaction energy was calculated using the classical 6-12 Lennard-Jones pairwise potential plus a Coulomb term on a rigid six-site molecular model with the potential parameters being optimized in this work. Theoretical values obtained for heat of vaporization and liquid densities are in good agreement with the experimental data. The radial distribution function [RDF, g(r)] obtained compare well with R-X diffraction data available. The RDF and molecular mechanics (MM2) minimization show that the C-H ⋯ O interaction has a significant role in the structure of the three liquids. These results are supported by ab initio calculations. This interaction is particularly important in the structure of MF. The intensity of the N - H ⋯ O hydrogen bond is greater in the MF than formamide. This could explain some anomalous properties verified in MF. © 1997 John Wiley & Sons, Inc.

Structure and weak hydrogen bonds in liquid acetaldehyde

Monte Carlo simulations have been performed to investigate the structure and hydrogen bonds formation in liquid acetaldehyde. An all atom model for the acetaldehyde have been optimized in the present work. Theoretical values obtained for heat of vaporisation and density of the liquid are in good agreement with experimental data. Graphics of radial distribution function indicate a well structured liquid compared to other similar dipolar organic liquids. Molecular mechanics minimization in gas phase leads to a trimer of very stable structure. The geometry of this complex is in very good agreement with the rdf. The shortest site-site correlation is between oxygen and the carbonyl hydrogen, suggesting that this correlation play a important role in the liquid structure and properties. The O⋯H average distance and the C-H⋯O angle obtained are characteristic of weak hydrogen bonds.

Capital flows to Latin America: quarterly developments

Includes bibliography

Capital flows to Latin America: recent developments

The external environment has deteriorated sharply as a result of the spiraling financial turmoil, and has led to a weakening in commodity prices and fears of a worldwide recession. Latin America and the Caribbean's fastest expansion in 40 years may be threatened as the global credit crunch makes financing scarce and squeezes demand for the region's commodities. This time around the region is better positioned to weather the crisis than in the past, given improvements in macroeconomic and financial policies as well as a reduced net dependency on external capital inflows. However, Latin American markets are feeling the effects of the crisis through a slowdown in capital inflows, large declines in stock price indexes, significant currency adjustments and an increase in debt spreads. Volatility has soared, with the closely watched Chicago Board Options Exchange Volatility Index moving to an all-time high of 70.33 on October 17, indicating that fear (rather than greed) has been ruling the markets.After reaching record lows in May 2007, emerging markets bond spreads are now above pre-Asian crisis levels. The JPMorgan EMBI+ Latin American composite widened by 146 basis points in the third quarter, with spreads reaching 448 basis points at the end of September. Spreads have widened sharply in recent weeks as foreign investors cut back regional exposure for the safety of U.S. Treasuries. The ongoing lack of liquidity and subsequent liquidation of assets is leading to a collapse in asset prices and a sharp widening in spreads. Daily spreads in October have risen to levels not seen since December 2002, making it much more difficult for governments that need financing to get it. Risk premiums for Latin corporates and sovereigns have risen substantially, but have remained well below U.S. junk (high-yield) bonds. Latin corporates are facing a steep rise in foreign exchange borrowing costs (although less than firms in other emerging markets), which raises concerns that refinancing risks will climb.So far, emerging markets vulnerabilities have been more focused on corporates, as sovereigns have improved public debt dynamics and countries' financing needs are under control. Market performance has been driven by the rapid deterioration of emerging markets bank and corporate market, as well as ongoing losses in emerging markets equities. From January to September 2008, the Morgan Stanley Capital International (MSCI) Latin American Index lost almost 28%, while the Emerging Markets Index lost 37% and the G-7 Index lost 24%. While in 2007 the Latin America component gained 47%, almost nine times as much as the MSCI-G7 index for developed markets, since mid-September 2008 stocks in Latin America have been doing worse than stocks in developed countries, as concerns about access to credit and the adverse impact of sharp falls in commodity prices and in local currencies contribute to increased risk aversion and to outflows of capital. Many governments in the region have used revenue from the commodity boom to pay down debt and build reserves. Now, facing a global financial crisis and the threat of recession in developed countries, the biggest question for Latin America is how long and deep this cyclical downturn will be, and how much it is going to reduce commodity prices. Prices for commodities such as soy, gold, copper and oil, which helped fund the region's boom, have fallen 28% since their July 2 high, according to the RJ/CRB Commodity Price Index. According to Morgan Stanley (in a September 29 report), should prices return to their 10-year average, Latin America's balanced budgets would quickly revert to a deficit of 4.1% of GDP. As risk aversion increases, investors are rapidly pulling out massive amounts of money, creating problems for local markets and banks. There is an ongoing shortage of dollars (as investors liquidate assets in Latin American markets), and as currencies depreciate, inflation concerns increase despite the global slowdown. In Brazil and Mexico, central banks deployed billions of dollars of reserves to stem steep currency declines, as companies in these countries, believing their local currencies would continue to strengthen against the U.S. dollar, took debts in dollars. Some companies also made bets using currency derivatives that have led to losses in the billions of dollars. Dramatic currency swings have caused heavy losses for many companies, from Mexico's cement giant Cemex SAB to the Brazilian conglomerate Grupo Votorantim. Mexico's third-largest retailer, Controladora Comercial Mexicana, declared bankruptcy recently after reporting huge losses related to exchange rate bets. As concerns about corporate exposure to dollar-denominated derivatives increases, yields on bonds issued by many of Brazil's and Mexico's leading companies have started to rise, sharply raising the cost of issuing new debt. Latin American external debt issuance came to a halt in the third quarter of 2008, totaling only US$ 690 million. The cost of obtaining loans for capital expenditures, M&A and debt refinancing is also rising substantially for Latin American corporates amid contagion from the U.S. financial crisis. According to bankers, a protracted trend of shortening tenors and widening spreads has intensified in the past few weeks, indicating that bank lending is quickly following the way of bonds and equity. Finally, money transfers from Latin American migrants are expected to decline for the first time this decade, as a result of economic downturns in the U.S. and Spain, inflation and a weaker dollar. The Mexican Central Bank announced that money transfers from Mexicans living in the U.S. dropped a record 12.2% in August. In 2008, migrants from the region will send some 1.7% less in remittances year-on-year when adjusted for inflation, according to the IADB, compounding the adverse effects of the deepening financial turmoil.

Exposed Collagen In Resin Bonds to Caries-affected Dentin After Dentin Treatment with Aqueous and Alcoholic Chlorhexidine Solutions

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Increased durability of resin-dentin bonds following cross-linking treatment

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Durable bonds at the adhesive/dentin interface: an impossible mission or simply a moving target?

Composite restorations have higher failure rates, more recurrent caries and increased frequency of replacement as compared to dental amalgam. Penetration of bacterial enzymes, oral fluids, and bacteria into the crevices between the tooth and composite undermines the restoration and leads to recurrent decay and failure. The gingival margin of composite restora tions is particularly vulnerable to decay and at this margin, the adhesive and its seal to dentin provides the primary barrier between the prepared tooth and the environment. The intent of this article is to examine physico-chemical factors that affect the integrity and durability of the adhesive/dentin interfacial bond; and to explore how these factors act synergistically with mechanical forces to undermine the composite restoration. The article will examine the various avenues that have been pursued to address these problems and it will explore how alterations in material chemistry could address the detrimental impact of physico-chemical stresses on the bond formed at the adhesive/dentin interface.

Exponential depletion of neutral dangling bonds density (D-0) by rare-earth doping in amorphous Si films

In this work we study the effect reduction in the density of dangling bond species D-0 states in rare-earth (RE) doped a-Si films as a function concentration for different RE-specimens. The films a-Si-1_(x) REx, RE=Y3+, Gd3+, Er3+, Lu3+) were prepared by co-sputtering and investigated by electron spin resonance (ESR) and Raman scattering experiments. According to our data the RE-doping reduces the ESR signal intensity of the D-0 states with an exponential dependence on the rare-concentration. Furthermore, the reduction produced by the magnetic rare-earths Gd3+ and Er3+ is remarkably greater than that caused by Y3+ and Lu3+, which led us to suggest an exchange-like coupling between the spin of the magnetic REs3+ and the spin of silicon neutral dangling bonds. (C) 2011 Elsevier B.V. All rights reserved.