Searching for emission-line galaxies: The UCM survey

We are carrying out a long-term project with the main purposes of finding and analyzing low metallicity galaxies. A very small number of very low metallicity galaxies is known up to now. However these ojbects are particularly interesting since they are excellent candidates to 'young galaxies' in evolutionary sense as POX186 (Kunth, Maurogordato & Vigroux, 1988). Since the interstellar matter in these objects is only weakly contaminated by stellar evolution, their study could provide valuable information about the primordial helium abundance and therefore it could place constraints on the different Big-Bang models. The instrumental set up of our survey is an objective-prism used with the Schmidt telescope at Calar Alto Observatory. By using hypersensitized IIIaF emulsion and RG630 filter low resolution spectra in the H alpha region of objects in a wide field is obtained (Rego et al. 1989, Zamorano et al. 1990). Surveys carried out in the past two decades at optical blue wavelengths have also produced large samples of emission-line galaxies (ELGs), for example MacAlpine & Willians 1981 and reference therein, Wasilewski 1983, Salzer and MacAlpine 1988, or Smith et al. 1976. Relying primarily on objective-prism plates taken in the blue, these surveys have found over 3000 blue/emission-line galaxies so far. A significant number of star-forming galaxies are missed by optical surveys in the blue because of their low-excitation spectra (MacAlpine and Willians 1981, Markarian et al. 1981 and references therein) or their low metallicity (Kunth and Sargent, 1986)

Interest rate risk immunization - the impact of credit risk in the quality of immunization case study: immunization with Portuguese bonds and German bonds

This paper involves an assessment of the interest rate risk present in Financial Institutions and the methods used for its immunization. The paper consists on two parts. The first part presents a theoretical review of the interest rate risk and how this risk can be immunized. Concepts such as Macaulay (1938) and Fisher & Weil (1971) duration and their limitations in the process of the approximation to the price of a considered bond will be highlighted. In the second part the main indicators of the credit risk on bonds are analyzed. Based on market prices of Portugal’s bonds and Germany’s bonds, the quality of immunization is tested. The interest rate derivatives are then introduced as a method of hedging interest rate risk. At the end, an interview is conducted with the responsible for hedging the interest rate risk in one of the largest private banks in Portugal in order to identify the methods used to capture the interest rate risk and to understand how this risk is immunized. This paper allows us to conclude about the importance of credit risk in an immunization strategy of interest rate risk. We conclude that interest rate hedging based on Fisher & Weil (1971) duration is not possible in a scenario of high volatility of credit risk. Interest rate hedge based on interest rate swap becomes more attractive to the Financial Institutions

On Chaotic Behavior of ASH Attractors

The asymptotic sectional hyperbolicity is a weak notion of hyperbolicity that extends properly the sectional-hyperbolicity and includes the Rovella attractor as a archetypal example. The main feature of this definition is the existence of arbitrarily large hyperbolic times for points outside the stable manifolds of the singularities. In this paper we will prove that any attractor associated to a $C^1$ vector field $X$ on a three-dimensional manifold satisfying this kind of hyperbolicity is rescaling-expansive and presents sensitiveness respect to initial conditions.Comment: 20 pages, 1 figur