Comparison of non-linear optimization algorithms for yield curve estimation

The yield curve is a very important financial tool used in investment and policy decisions. Its estimation from market data is essentially a non-linear optimization problem. In this paper, we compare a diversity of non-linear optimization algorithms for estimating yield curves based on actual bond market data and conclude that certain classes of algorithms are more effective due to the nature of the problem.     

Some properties of Baire sets and sets of positive measure

In un lavoro classico Steinhaus ha dimostrato undici teoremi interessanti nei quali si considerano insiemi distanziali di sottoinsiemi della linea reale,aventi misura di Lebesgue positiva. Majumder ha dimostrato che sono validi teoremi analoghi a quelli di Steinhaus per insiemi del tipoR(E)={x/y: x,y∈E} doveE∪R; 0?E. In questo lavoro si considerano funzioni generali e si investiga sui quali degli undici teoremi di Steinhaus possono essere generalizzati. Nell'articolo, inoltre, usando una funzione generalef, vengono dati risultati analoghi a quelli di Steinhaus per insiemi di Baire.     

On embeddings of proper and equicontinuous actions in zero-dimensional compactifications

We provide a tool for studying properly discontinuous actions of non-compact groups on locally compact, connected and paracompact spaces, by embedding such an action in a suitable zero-dimensional compactification of the underlying space with pleasant properties. Precisely, given such an action we construct a zero-dimensional compactification of with the properties: (a) there exists an extension of the action on , (b) if is the set of the limit points of the orbits of the initial action in , then the restricted action remains properly discontinuous, is indivisible and equicontinuous with respect to the uniformity induced on by that of , and (c) is the maximal among the zero-dimensional compactifications of with these properties. Proper actions are usually embedded in the endpoint compactification of , in order to obtain topological invariants concerning the cardinality of the space of the ends of , provided that has an additional ``nice" property of rather local character (``property Z", i.e., every compact subset of is contained in a compact and connected one). If the considered space has this property, our new compactification coincides with the endpoint one. On the other hand, we give an example of a space not having the ``property Z" for which our compactification is different from the endpoint compactification. As an application, we show that the invariant concerning the cardinality of the ends of holds also for a class of actions strictly containing the properly discontinuous ones and for spaces not necessarily having ``property Z".

     

Curcumin Formulations and Trials: What’s New in Neurological Diseases

Curcumin’s pharmacological properties and its possible benefits for neurological diseases and dementia have been much debated. In vitro experiments show that curcumin modulates several key physiological pathways of importance for neurology. However, in vivo studies have not always matched expectations. Thus, improved formulations of curcumin are emerging as powerful tools in overcoming the bioavailability and stability limitations of curcumin. New studies in animal models and recent double-blinded, placebo-controlled clinical trials using some of these new formulations are finally beginning to show that curcumin could be used for the treatment of cognitive decline. Ultimately, this work could ease the burden caused by a group of diseases that are becoming a global emergency because of the unprecedented growth in the number of people aged 65 and over worldwide. In this review, we discuss curcumin’s main mechanisms of action and also data from in vivo experiments on the effects of curcumin on cognitive decline.     

Kompaktheitseigenschaften der Gruppe der Isometrien metrischer Räume

Ohne Zusammenfassung     

Eine Charakterisierung derD +-stabilen Dynamischen Systeme auf lokal kompakten metrisierbaren Räumen

Ohne Zusammenfassung     

Parameter identification of 1D fractal interpolation functions using bounding volumes

Fractal interpolation functions are very useful in capturing data that exhibit an irregular (non-smooth) structure. Two new methods to identify the vertical scaling factors of such functions are presented. In particular, they minimize the area of the symmetric difference between the bounding volumes of the data points and their transformed images. Comparative results with existing methods are given that establish the proposed ones as attractive alternatives. In general, they outperform existing methods for both low and high compression ratios. Moreover, lower and upper bounds for the vertical scaling factors that are computed by the first method are presented.     

On Riemannian coverings of manifolds admitting locally splitting actions

By studying the structure of certain covering manifolds, associated with a series of subgroups of ₁(M), we approximate the structure of the Riemannian manifoldM, provided that it admits a locally splitting action. The above series arises because of the local splitting of the action and the study is carried out via initial data. Also, we indicate how manifolds without conjugate points can be investigated using locally splitting actions of abelian Lie groups.