A Unifying Framework for Finite Wordlength Realizations.

A general framework for the analysis of the finite wordlength (FWL) effects of linear time-invariant digital filter implementations is proposed. By means of a special implicit system description, all realization forms can be described. An algebraic characterization of the equivalent classes is provided, which enables a search for realizations that minimize the FWL effects to be made. Two suitable FWL coefficient sensitivity measures are proposed for use within the framework, these being a transfer function sensitivity measure and a pole sensitivity measure. An illustrative example is presented

Fast acoustic tweezers for the two-dimensional manipulation of individual particles in microfluidic channels

This paper presents a microfluidic device that implements standing surface acoustic waves in order to handle single cells, droplets, and generally particles. The particles are moved in a very controlled manner by the two-dimensional drifting of a standing wave array, using a slight frequency modulation of two ultrasound emitters around their resonance. These acoustic tweezers allow any type of motion at velocities up to few 10mm/s, while the device transparency is adapted for optical studies. The possibility of automation provides a critical step in the development of lab-on-a-chip cell sorters and it should find applications in biology, chemistry, and engineering domains

Intergenerational altruism and neoclassical growth models

This paper surveys intergenerational altruism in neoclassical growth models. It first examines Barro's approach to intergenerational altruism, whereby successive generations are linked by recursive altruistic preferences. Individuals have an altruistic concern only for their children, who in turn also have altruistic feelings for their own children. The conditions under which the Ricardian equivalence (debt neutrality) theorem applies are specified. The effectiveness of fiscal policy is further analysed in the context of an economy populated by heterogeneous families differing with respect to their degree of intergenerational altruism. Other forms of altruism, referred to as ad hoc altruism, are also examined, along with their implications for fiscal policy. JEL Classification: E13, D64, E62, C60altruism, fiscal policy, Neoclassical general aggregative models