The compact group--fossil group connection: observations of a massive compact group at z=0.22

It has been suggested that fossil groups could be the cannibalized remains of compact groups, that lost energy through tidal friction. However, in the nearby universe, compact groups which are close to the merging phase and display a wealth of interacting features (such as HCG 31 and HCG 79) have very low velocity dispersions and poor neighborhoods, unlike the massive, cluster-like fossil groups studied to date. In fact, known z=0 compact groups are very seldom embedded in massive enough structures which may have resembled the intergalactic medium of fossil groups. In this paper we study the dynamical properties of CG6, a massive compact group at z=0.220 that has several properties in common with known fossil groups. We report on new g' and i' imaging and multi-slit spectroscopic performed with GMOS on Gemini South. The system has 20 members, within a radius of 1 h_70^-1 Mpc, a velocity dispersion of 700 km/s and has a mass of 1.8 x 10^14 h_70^-1 Msun, similar to that of the most massive fossil groups known. The merging of the four central galaxies in this group would form a galaxy with magnitude M_r' ~ -23.4, typical for first-ranked galaxies of fossil groups. Although nearby compact groups with similar properties to CG 6 are rare, we speculate that such systems occurred more frequently in the past and they may have been the precursors of fossil groups.Comment: 7 pages, 3 figures (one color, low resolution), uses emulateapj.sty. Accepted for publication in ApJ Lette

A relational theory of relationship lending under contractual incompleteness

While the literature has focused on relationships as a technology for solving hidden information problems in credit markets, hidden action has been very little explored as an explanation for the existence of relational lending. In this paper, we propose a theory in which relationships are driven by the problem of contractual incompleteness in instances in which a borrower, by taking ex-ante actions, magnifies the hazards related to ex-post bargaining over returns. A relationship commits the borrower to take actions that minimize the ex-post conflict of interests resulting from contractual incompleteness. We show that a robust feature of an optimally designed lending relationship (i.e., the best Public Perfect Pure Strategy Equilibrium in a repeated lending game) is that a sufficiently patient entrepreneur, upon choosing his actions, ignores his privately observed contingencies. This commitment solves the credit rationing problem that arises in a one-shot (arm’s length) interaction, and reduces, when compared to arm’s length financing, the interest rate that a bank charges for a credit line. Although in a less acute fashion, we also show that the same features just described appear in an optimal lending relationship for the case in which the entrepreneur is impatient.

Relationship lending: Is it Incentives or hidden information?

Relationships are a valuable technology to produce loans. (Berger and Udell [1995], Petersen and Rajan [1994], Aoki and Dinç [2002]). While there are convincing theories in which relationships solve hidden action or hidden information problems, there is very little empirical corroboration of either theory. In this paper, we assess the empirically validity of these theories in the small firm credit market. While results suggest that relationships are more valuable for firms with worse incentive misaligment problems, more informationally opaque firms do not seem to extract more value from relationships. Contrary to what most empirical research on the value of relationships has assumed (but not tested), this indicates that relationships are, at very least, as important for aligning incentives as they are for solving hidden information problems.

Nuclear Many-Body Theory of Electroweak Interactions with Nuclei at Intermediate Energies

The Quasi-Elastic (QE) contribution of the nuclear inclusive electron model developed in reference \cite{GNO97} is extended to the study of electroweak Charged Current (CC) induced nuclear reactions at intermediate energies of interest for future neutrino oscillation experiments. Long range nuclear (RPA) correlations, Final State Interaction (FSI) and Coulomb corrections are included within the model. RPA correlations are shown to play a crucial role in the whole range of neutrino energies, up to 500 MeV, studied in this work. Predictions for inclusive muon capture for different nuclei through the Periodic Table and for the reactions $^{12}$C $(\nu_\mu,\mu^-)X$ and $^{12}$C $(\nu_e,e^-)X$ near threshold are also given.Comment: Talk given by J. Nieves at NUINT04, Gran Sasso, March 200

Filogeografía y Biología de Eiseniella tetraedra (Savigny, 1826)

Tesis inédita de la Universidad Complutense de Madrid, Facultad de Ciencias Biológicas, leída el 18-02-2022The aim of this Ph.D. dissertation is to increase the knowledge about cosmopolitan and parthenogenetic earthworms. For this purpose, the earthworm Eiseniella tetraedra (Savigny, 1826) was chosen as a model. Although there have been studies on other earthworm species with the same characteristics, no work has ever been done that includes so many individuals and populations. On the other hand, its relationship with other species of the same genus has been studied using molecular markers and traditional techniques such as the study of its morphology. Finally, new generation sequencing techniques were used to determine changes in the gene expression profile of E. tetraedra under different abiotic stressors...La presente Tesis Doctoral pretende incrementar el conocimiento sobre las lombrices de tierra cosmopolitas y partenogenéticas. Para ello, se eligió como modelo la lombriz Eiseniella tetraedra (Savigny, 1826). A pesar de que existen estudios sobre otras especies de lombriz con las mismas características, nunca se había desarrollado un trabajo que incluyera tantos individuos y poblaciones. Por otro lado, se estudió su relación con otras especies del mismo género en base a marcadores moleculares y técnicas tradicionales como el estudio de su morfología. Finalmente, se emplearon técnicas de secuenciación de nueva generación para poder definir cambios en el perfil de expresión genética en E: tetraedra bajo distintos estresores abióticos...Fac. de Ciencias BiológicasTRUEunpu

New space vector modulation algorithms applied to multilevel converters with balanced DC-link voltage

This work presents a survey of new space vector modulation algorithms for high power voltage source multilevel converters. These techniques provide the nearest switching vectors sequence to the reference vector and calculates the on-state durations of the respective switching state vectors without involving trigonometric functions, look-up tables or coordinate system transformations which increase the computational load corresponding to the modulation of a multilevel converter. These algorithms drastically reduce the computational load maintained permitting the on-line computation of the switching sequence and the on-state durations of the respective switching state vectors. The on-state durations are reduced to a simple addition. In addition, the low computational cost of the proposed methods is always the same and it is independent of the number of levels of the converter. The algorithms have been satisfactorily implemented in very low-cost microcontrollers.Ministerio de Ciencia y Tecnología DPI 2001-308

A quantum mechanical study of the phase stability and phase transition mechanisms in CaCO3 at finite temperature and pressure

First-principles calculations have been performed to explore the temperature-pressure phase diagram of calcium carbonate (CaCO3) in a range of temperatures and pressures up to 1000 K and 10 GPa respectively. The calcite I - calcite II and calcite I - aragonite phase boundaries have been obtained. Imaginary phonon modes in the aragonite phase suggest pathways to three distinct alternative phases that involve symmetry breaking and distortion of the unit cell. The variation of the Gibbs free energy with pressure and temperature has been computed in the quasi-harmonic approximation. Several approaches have been discussed in this thesis for the most accurate determination of the temperature - pressure phase boundary. A method for determining the calcite I - calcite II second order phase boundary has been described in this work. Hybrid exchange and GGA density functional theory in the all-electron linear combination of atomic orbitals approximation have been exploited, as well as the effect of the inclusion of van der Waals dispersion corrections. The resultant theoretical phase diagram is compared to the available measurements. The detailed theoretical understanding of the phase transitions mechanisms developed in this thesis sets the basis for a future exploration of the thermodynamic stability phase of CaCO3. In this respect, the methodology described in this work could be used to predict the temperature - pressure phase boundaries of the rest of the polymorphs of this complex system, e.g. phase transitions occurring in calcite III, IIIb, IV, V and VI.Open Acces