920 resultados para Expectations hypothesis of term struscture of interest rates
Resumo:
This research analyses the influence of the macroeconomic factors on the primary issue of stocks and debentures in the Brazilian market. Previous studies have agreed on the importance of aspects of the economic situation on a companys capital structure, but have not established a relationship between the macroeconomic variables and the level of aggregate debt; we can mention Procianoy and Caselani (1997) and Terra (2003) as examples of this. According to Leal (2000), the limitations of the Brazilian capital market suggest that management takes advantage of moments of euphoria in the market - whether caused by a reduction in the rate of interest or by the return being offered by the equity market - to raise funds at rates that are more advantageous to the company. This characterizes the first evidence we have of opportunistic behavior influencing a companys financing decisions. Eid Jr. (1996) provides us with the first evidence of this opportunistic behavior in his research in which 47% of those interviewed said that they chose fund sources that are economically more advantageous.
Resumo:
We study the relationship between the volatility and the price of stocks and the impact that variables such as past volatility, financial gearing, interest rates, stock return and turnover have on the present volatility of these securities. The results show the persistent behavior of volatility and the relationship between interest rate and volatility. The results also showed that a reduction in stock prices are associated with an increase in volatility. Finally we found a greater trading volume tends to increase the volatility.
Resumo:
This paper argues the euro zone requires a government banker that manages the bond market and helps finance country budget deficits. The euro solved Europes problem of exchange rate speculation by creating a unified currency managed by a single central bank, but in doing so it replaced the exchange rate speculation problem with bond market speculation. Remedying this requires a central bank that acts as government banker and maintains bond interest rates at sustainable levels. Because the euro is a monetary union, this must be done in a way that both avoids favoring individual countries and avoids creating incentives for irresponsible country fiscal policy that leads to bail-outs. The paper argues this can be accomplished via a European Public Finance Authority (EPFA) that issues public debt which the European Central Bank (ECB) is allowed to trade. The debate over the euros financial architecture has significant political implications. The current neoliberal inspired architecture, which imposes a complete separation between the central bank and public finances, puts governments under continuous financial pressures. That will make it difficult to maintain the European social democratic welfare state. This gives a political reason for reforming the euro and creating an EPFA that supplements the economic case for reform.
Resumo:
The recent process of accelerated expansion of the Brazilian economy was driven by exports and fixed capital formation. Although the pace of growth was more robust than in the 1990s, we can still witness the existence of certain macroeconomic constraints to its continuation in the long run such as, for instance, the exchange rate overvaluation in particular since 2005, and in general the modus operandi of monetary policy. Such constraints may jeopardize the sustainability of the current pace of growth. Therefore, we argue that Brazil still lies in a trap made up of high interest and low exchange rates. The elimination of the exchange rate misalignment would bring about a great increase in the rate of interest, which on its turn would impact negatively upon investment and hence upon the sustainability of long run economic growth. We outline a set of policy measures to eliminate such a trap, in particular, the adoption of an implicit target for the exchange rate, capital controls and the abandonment of the present regime of inflation targeting. Recent events seem to go in this direction.
Resumo:
This paper employs mechanism design to study the effects of imperfect legal enforcement on optimal scale of projects, borrowing interest rates and the probability of default. The analysis departs from an environment that combines asymmetric information about cash flows and limited commitment by borrowers. Incentive for repayment comes from the possibility of liquidation of projects by a court, but courts are costly and may fail to liquidate. The value of liquidated assets can be used as collateral: it is transferred to the lender when courts liquidate. Examples reveal that costly use of courts may be optimal, which contrasts with results from most limited commitment models, where punishments are just threats, never applied in optimal arrangements. I show that when voluntary liquidation is allowed, both asymmetric information and uncertainty about courts are necessary conditions for legal punishments ever to be applied. Numerical solutions for several parametric specifications are presented, allowing for heterogeneity on initial wealth and variability of project returns. In all such solutions, wealthier individuals borrow with lower interest rates and run higher scale enterprises, which is consistent with stylized facts. The reliability of courts has a consistently positive effect on the scale of projects. However its effect on interest rates is subtler and depends essentially on the degree of curvature of the production function. Numerical results also show that the possibility of collateral seizing allows comovements of the interest rates and the probability of repayment.
Resumo:
Attanasio et al. (JPE, 2002) have used microeconomic data on households to provide new estimates of the welfare costs of infiation using Bailey's unidimensional welfare measure as a basis for their calculations. Such a measure does not properly take into consideration lhe fact that the majority of households in their sample (58.7 percent) holds not only bank deposits and currency, but also a second type of interest-bearing assct. This work devises alternative formulas which account for the existence of bank deposits and a sccond interest-bearing asset in the economy, as well as for adoption decisions regarding alternative financiai technologies.
Resumo:
Logo aps crise financeira de 2007-08 o Federal Reserve interveio para tentar controlar a recesso. No entanto, ele no apenas baixou os juros, como tambm adotou polticas no-convencionais, incluindo o emprstimo direto para empresas em mercados de crdito de alto nvel. Estas novas medidas foram controversas e alguns opositores protestaram porque elas estariam ajudando disproporcionalmente aquelas pessoas ligadas ao sistema financeiro que j eram ricas. Ns utilizamos um modelo DSGE para a anlise de polticas monetria no convencional e introduzimos dois tipos distintos de agentes, capitalistas e trabalhadores, para investigar o seu impacto distributivo. Ns encontramos que a poltica de crdito to Fed foi bem sucedida no mercado de trabalho, o que ajuda mais os trabalhadores, e introduziu um novo competidor no mercado bancrio, o governo, o que prejudica mais os capitalistas. Logo, ns encontramos que a poltica de crdito diminuiu a desigualdade nos EUA.
Resumo:
Disease, injury, and age problems compromise human quality of life and continuously motivate the search for new and more efficacious therapeutic approaches. The field of Tissue Regeneration and Engineering has greatly evolved over the last years, mainly due to the combination of the important advances verified in Biomaterials Science and Engineering with those of Cell and Molecular Biology. In particular, a new and promising area arose Nanomedicine that takes advantage of the extremely small size and especial chemical and physical properties of Nanomaterials, offering powerful tools for health improvement. Research on Stem Cells, the self-renewing progenitors of body tissues, is also challenging to the medical and scientific communities, being expectable the appearance of new and exciting stem cell-based therapies in the next years. The control of cell behavior (namely, of cell proliferation and differentiation) is of key importance in devising strategies for Tissue Regeneration and Engineering. Cytokines, growth factors, transcription factors and other signaling molecules, most of them proteins, have been identified and found to regulate and support tissue development and regeneration. However, the application of these molecules in long-term regenerative processes requires their continuous presence at high concentrations as they usually present short half-lives at physiological conditions and may be rapidly cleared from the body. Alternatively, genes encoding such proteins can be introduced inside cells and be expressed using cells machinery, allowing an extended and more sustained production of the protein of interest (gene therapy). Genetic engineering of stem cells is particularly attractive because of their self-renewal capability and differentiation potential. For Tissue Regeneration and Engineering purposes, the patients own stem cells can be genetically engineered in vitro and, after, introduced in the body (with or without a scaffold) where they will not only modulate the behavior of native cells (stem cell-mediated gene therapy), but also directly participate in tissue repair. Cells can be genetically engineered using viral and non-viral systems. Viruses, as a result of millions of years of evolution, are very effective for the delivery of genes in several types of cells, including cells from primary sources. However, the risks associated with their use (like infection and immunogenic reactions) are driving the search for non-viral systems that will efficiently deliver genetic material into cells. Among them, chemical methods that are promising and being investigated use cationic molecules as carriers for DNA. In this case, gene delivery and gene expression level remain relatively low when primary cells are used. The main goal of this thesis was to develop and assess the in vitro potential of polyamidoamine (PAMAM) dendrimers based carriers to deliver genes to mesenchymal stem cells (MSCs). PAMAM dendrimers are monodispersive, hyperbranched and nanospherical molecules presenting unique characteristics that make them very attractive vehicles for both drug and gene delivery. Although they have been explored for gene delivery in a wide range of cell lines, the interaction and the usefulness of these molecules in the delivery of genes to MSCs remains a field to be explored. Adult MSCs were chosen for the studies due to their potential biomedical applications (they are considered multipotent cells) and because they present several advantages over embryonic stem cells, such as easy accessibility and the inexistence of ethical restrictions to their use. This thesis is divided in 5 interconnected chapters. Chapter I provides an overview of the current literature concerning the various non-viral systems investigated for gene delivery in MSCs. Attention is devoted to physical methods, as well as to chemical methods that make use of polymers (natural and synthetic), liposomes, and inorganic nanoparticles as gene delivery vectors. Also, it summarizes the current applications of genetically engineered mesenchymal stem cells using non-viral systems in regenerative medicine, with special focus on bone tissue regeneration. In Chapter II, the potential of native PAMAM dendrimers with amine termini to transfect MSCs is evaluated. The level of transfection achieved with the dendrimers is, in a first step, studied using a plasmid DNA (pDNA) encoding for the -galactosidase reporter gene. The effect of dendrimers generation, cell passage number, and N:P ratio (where N= number of primary amines in the dendrimer; P= number of phosphate groups in the pDNA backbone) on the level of transfection is evaluated, being the values always very low. In a second step, a pDNA encoding for bone morphogenetic protein-2, a protein that is known for its role in MSCs proliferation and differentiation, is used. The BMP-2 content produced by transfected cells is evaluated by an ELISA assay and its effect on the osteogenic markers is analyzed through several classical assays including alkaline phosphatase activity (an early marker of osteogenesis), osteocalcin production, calcium deposition and mineralized nodules formation (late osteogenesis markers). Results show that a low transfection level is enough to induce in vitro osteogenic differentiation in MSCs. Next, from Chapter III to Chapter V, studies are shown where several strategies are adopted to change the interaction of PAMAM dendrimers with MSCs cell membrane and, as a consequence, to enhance the levels of gene delivery. In Chapter III, generations 5 and 6 of PAMAM dendrimers are surface functionalized with arginine-glycine-aspartic acid (RGD) containing peptides experiments with dendrimers conjugated to 4, 8 and 16 RGD units were performed. The underlying concept is that by including the RGD integrin-binding motif in the design of the vectors and by forming RGD clusters, the level of transfection will increase as MSCs highly express integrins at their surface. Results show that cellular uptake of functionalized dendrimers and gene expression is enhanced in comparison with the native dendrimers. Furthermore, gene expression is dependent on both the electrostatic interaction established between the dendrimer moiety and the cell surface and the nanocluster RGD density. In Chapter IV, a new family of gene delivery vectors is synthesized consisting of a PAMAM dendrimer (generation 5) core randomly linked at the periphery to alkyl hydrophobic chains that vary in length and number. Herein, the idea is to take advantage of both the cationic nature of the dendrimer and the capacity of lipids to interact with biological membranes. These new vectors show a remarkable capacity for internalizing pDNA, being this effect positively correlated with the CH2 content present in the hydrophobic corona. Gene expression is also greatly enhanced using the new vectors but, in this case, the higher efficiency is shown by the vectors containing the smallest hydrophobic chains. Finally, chapter V reports the synthesis, characterization and evaluation of novel gene delivery vectors based on PAMAM dendrimers (generation 5) conjugated to peptides with high affinity for MSCs membrane binding - for comparison, experiments are also done with a peptide with low affinity binding properties. These systems present low cytotoxicity and transfection efficiencies superior to those of native dendrimers and partially degraded dendrimers (Superfect, a commercial product). Furthermore, with this biomimetic approach, the process of gene delivery is shown to be cell surface receptor-mediated. Overall, results show the potential of PAMAM dendrimers to be used, as such or modified, in Tissue Regeneration and Engineering. To our knowledge, this is the first time that PAMAM dendrimers are studied as gene delivery vehicles in this context and using, as target, a cell type with clinical relevancy. It is shown that the cationic nature of PAMAM dendrimers with amine termini can be synergistically combined with surface engineering approaches, which will ultimately result in suitable interactions with the cytoplasmic membrane and enhanced pDNA cellular entry and gene expression. Nevertheless, the quantity of pDNA detected inside cell nucleus is always very small when compared with the bigger amount reaching cytoplasm (accumulation of pDNA is evident in the perinuclear region), suggesting that the main barrier to transfection is the nuclear membrane. Future work can then be envisaged based on the versatility of these systems as biomedical molecular materials, such as the conjugation of PAMAM dendrimers to molecules able to bind nuclear membrane receptors and to promote nuclear translocation.
Resumo:
The functional response between ingestion rate and food concentration was determined for each larval stage of Macrobrachium rosenbergii. Artemia franciscana nauplii were supplied at 2,4, 6, 8, 10 and 12 per milliliter. The nauplii were counted by sight using a Pasteur pipette and transferred to Petri dishes containing 40 ml of brackish water (12 parts per thousand) lying on the top of black plastic. One larva at each stage was individually placed into each Petri dish containing different food density. After 24 h, each larva was removed from the Petri dish and the leftover nauplii were counted. The amount consumed was determined by the difference between the initial and final number of nauplii. Ingestion rate (I) increased as food density (P) increased and was defined by the model I=I-m(1-e(-kP)). The results suggest four levels of ingestion during larval development. The first level includes stages II, III and IV, with average maximum consumption of about 40 nauplii/day; the second level includes stages V and VI, with consumption of approximately 55 nauplii/day; the third level includes stages VII and VIII, with consumption of 80-100 nauplii/day. The fourth level includes stages IX, X and XI, in which the high values for maximum ingestion (Im) exceed the load capacity of the medium. The low values for constant k (that may correspond to the adaptability of the food to prey characteristics, such as, size, mobility, etc.) obtained for stages IX, X and XI indicated that Artemia is not an adequate prey and there is necessity of a supplementary diet. The best relationship between predator and prey seemed to occur during stage IV Results obtained in the present work may subsidize future researches and serve as a guideline for practical considerations of feeding rates. (C) 2003 Elsevier B.V. B.V. All rights reserved.
Resumo:
Fundao de Amparo Pesquisa do Estado de So Paulo (FAPESP)
Resumo:
Amorphous hydrogenated chlorinated carbon (a-C:H:Cl) films were produced by the plasma polymerization of chloroform-acetylene-argon mixtures in a radiofrequency plasma enhanced chemical vapor deposition system. The main parameter of interest was the proportion of chloroform in the feed, R(C), which was varied from 0 to 80%. Deposition rates of 80 nm min (1) were typical for the chlorinated films. Infrared reflection-absorption spectroscopy revealed the presence of C-Cl groups in all the films produced with chloroform in the feed. X-ray photoelectron spectroscopy confirmed this finding, and revealed a saturation of the chlorine content at similar to 47 at.% for R(C)>= 40%. The refractive index and optical gap, E(04), of the films were roughly in the 1.6 to 1.7, and the 2.8 to 3.7 eV range. These values were calculated from transmission ultraviolet-visible-near infrared spectra. Chlorination leads to an increase in the water surface contact angle from similar to 40 degrees to similar to 77 degrees. (C) 2011 Elsevier B.V. All rights reserved.
Resumo:
Wood gasification technologies to convert the biomass into fuel gas stand out. on the other hand, producing electrical energy from stationary engine is widely spread, and its application in rural communities where the electrical network doesn't exist is very required. The recovery of exhaust gases (engine) is a possibility that makes the system attractive when compared with the same components used to obtain individual heat such as electric power. This paper presents an energetic alternative to adapt a fixed bed gasifier with a compact cogeneration system in order to cover electrical and thermal demands in a rural area and showing an energy solution for small social communities using renewable fuels. Therefore, an energetic and economical analysis from a cogeneration system producing electric energy, hot and cold water, using wooden gas as fuel from a small-sized gasifier was calculated. The energy balance that includes the energy efficiency (electric generation as well as hot and cold water system; performance coefficient and the heat exchanger, among other items), was calculated. Considering the annual interest rates and the amortization periods, the costs of production of electrical energy, hot and cold water were calculated, taking into account the investment, the operation and the maintenance cost of the equipments. Crown Copyright (C) 2010 Published by Elsevier Ltd. All rights reserved.
Resumo:
Background. Patients who develop acute kidney injury (AKI) in the intensive care unit (ICU) have extremely high rates of mortality and morbidity. The objectives of this study were to compare clinical and laboratory characteristics of AKI patients evaluated and not evaluated by nephrologists in ICU and generate the hypothesis of the relationship between timing of nephrology consultation and outcome.Methods. We explored associations among presence and timing of nephrology consultation with ICU stay and in-ICU mortality in 148 ICU patients with AKI at a Brazilian teaching hospital from July 2008 to May 2010. Multivariable logistic regression was used to adjust confounding and selection bias.Results. AKI incidence was 30% and 52% of these AKI patients were evaluated by nephrologists. At multivariable analysis, AKI patients evaluated by nephrologists showed higher Acute Tubular Necrosis-Index Specific Score and creatinine level, more dialysis indications, lower urine output and longer ICU stay. The mortality rate was similar to AKI patients who were not evaluated. Nephrology consultation was delayed (>= 48 h) in 62.3% (median time to consultation, 4.7 days). Lower serum creatinine levels (P - 0.009) and higher urine output (P = 0.002) were associated with delayed consultation. Delayed consultation was associated with increased ICU mortality (65.4 versus 88.2%, P < 0.001).Conclusions. In AKI, patients evaluated by nephrologists seem to be more seriously ill than those not evaluated and present similar mortality rate. The delayed nephrology consultation can be associated with increased ICU mortality.
Resumo:
OBJECTIVE: To evaluate quality of life in a population that attended a specific community event on health care education, and to investigate the association of their quality of life with the presence of cardiovascular risk factors INTRODUCTION: Interest in health-related quality of life is growing worldwide as a consequence of increasing rates of chronic disease. However, little is known about the association between quality of life and cardiovascular risk factors. METHODS: This study included 332 individuals. Demographics, blood pressure, body mass index, and casual glycemia were evaluated. The brief version of the World Health Organization Quality of Life questionnaire on quality of life was given to them. The medians of the scores obtained for the physical, psychological, emotional, and environmental domains were used as cutoffs to define higher and lower scores. A multinomial logistic regression model was used to define the parameters associated with lower scores. RESULTS: Diabetes mellitus, dyslipidemia, and obesity were associated with lower scores in the physical domain. Dyslipidemia was also associeted with lower scores in the psychological domain. Male gender and regular physical activity had protective effects on quality of life. Aging was inversely associated with decreased quality of life in the environmental domain. CONCLUSION: The presence of cardiovascular risk factors is related to a decreased quality of life. Conversely, male gender and regular physical activity had protective effects on quality of life. These findings suggest that exercising should be further promoted by health-related public programs, with a special focus on women.
Resumo:
Fundao de Amparo Pesquisa do Estado de So Paulo (FAPESP)