A model for the Yield curve

The starting point is an interrogation about the non-broken character of the term structure of interest rates. Some arguments for that smooth character are presented here, all of which are based upon the assumption that market participants - arbitrageurs and speculators - always try to explore any misalignments discovered in the interest market. This led to the basic concept behind the model that the current short-term rate determines most of the value of the rate level for the subsequent period. A linear model describing that simple relationship is assumed and that constitutes the building block from where one can develop the mathematical equations necessary to work with different sets of market data. A number of different yield curves were modelled by adjustment to real market data using this basic model, all of them showing a very high quality of the fits when measured by the non-linear ratio R2. Nevertheless this fact still needs to be confirmed as the examples were drawn from non-independent markets and from a very short time window. The model can be improved by simple addition of a liquidity premium depend only upon the maturity of the rates. However, that improvement sophisticates tremendously the mathematical tractability of any real situation without any assurance that this added cost compensates for the increased quality of the fit. The model is designed around only 3 parameters that can all be interpreted in economic terms. Two of them, in particular, bring a significant improvement over the traditional views frequently extracted from the shape of the yield curve. Provided future tests confirm the high quality of the basic and the improved (with a liquidity premium) models, both are supportive of the expectation hypothesis (EH) and the liquidity premium hypothesis (LPH).

Overconfidence and excess entry: a comparison between students and managers

Overconfidence can lead to excessive business entry. Here we replicate the pioneer experiment finding this nexus (Camerer and Lovallo 1999) and extend it in two major directions: (1) to consider managers as well as student subjects and (2) to explicitly take into account selected characteristics of the manager subjects. We find that managers are more prone to the nexus overconfidence-excess entry than students are. In particular, we find that left-handed, married, and emotionally aroused managers are more prone to excess entry.excess business entry, overconfidence, unrealistic optimism

Gauge Fixing in the Maxwell Like Gravitational Theory in Minkowski Spacetime and in the Equivalent Lorentzian Spacetime

In a previous paper we investigate a Lagrangian field theory for the gravitational field (which is there represented by a section g^a of the orthonormal coframe bundle over Minkowski spacetime. Such theory, under appropriate conditions, has been proved to be equivalent to a Lorentzian spacetime structure, where the metric tensor satisfies Einstein field equations. Here, we first recall that according to quantum field theory ideas gravitation is described by a Lagrangian theory of a possible massive graviton field (generated by matter fields and coupling also to itself) living in Minkowski spacetime. The graviton field is moreover supposed to be represented by a symmetric tensor field h carrying the representations of spin two and zero of the Lorentz group. Such a field, then (as it is well known), must necessarily satisfy the gauge condition given by Eq.(3) below. Next, we introduce an ansatz relating h to the 1-form fields g^a. Then, using the Clifford bundle formalism we derive, from our Lagrangian theory, the exact wave equation for the graviton and investigate the role of the gauge condition given by Eq.(3) in obtaining a reliable conservation law for the energy-momentum tensor of the gravitational plus the matter fields in Minkowski spacetime. Finally we ask the question: does Eq.(3) fix any gauge condition for the field g of the effective Lorentzian spacetime structure that represents the field h in our theory? We show that no gauge condition is fixed a priory, as is the case in General Relativity. Moreover we investigate under which conditions we may fix Logunov gauge condition.Comment: 15 pages. This version corrects some misprints of the published versio

Diffeomorphism Invariance and Local Lorentz Invariance

We show that diffeomorphism invariance of the Maxwell and the Dirac-Hestenes equations implies the equivalence among different universe models such that if one has a linear connection with non-null torsion and/or curvature the others have also. On the other hand local Lorentz invariance implies the surprising equivalence among different universe models that have in general different G-connections with different curvature and torsion tensors.Comment: 19 pages, Revtex, Plenary Talk presented at VII International Conference on Clifford Algebras and their Applications, Universite Paul Sabatier UFR MIG, Toulouse (FRANCE), to appear in "Clifford Algebras, Applications to Mathematics, Physics and Engineering", Progress in Math. Phys., Birkhauser, Berlin 200

A brief overview of current drug repurposing approaches for COVID-19 management

This brief overview is intended to shed light on the current drug repositioning (also called drug repurposing) in the therapeutics of the novel coronavirus disease which emerged in 2019 (COVID-19). In this sense, the repositioning drugs for new indications can offer a better risk-versus-reward trade-off when compared to other drug development strategies, given that it makes use of drugs whose safety profile are already understood. Nonetheless, this approach allows healthcare professionals to promptly tackle the disease by investigating readily available drugs against it