Life history and ecological genetics of the colonial ascidian Botryllus schlosseri

The colonial ascidian Botryllus schlosseri is a cosmopolitan, marine filter feeder, introduced as a laboratory research organism in the 1950s. Currently, it is widely used in many laboratories to investigate a variety of biological questions. Recently, it has become a species of concern, as it is an invasive species in many coastal environments. Here, we review studies on the geographical distribution of the species, sexual and asexual reproduction in the field, tolerance to temperature, salinity and anthropogenic activity, polychromatism, enzymatic polymorphism, and the genetic basis of pigmentation. Studying the relationship between genetic polymorphism and the adaptation of B. schlosseri to environmental stress is a challenge of future research and will improve our understanding of its evolutionary success and invasive potential

A multi-layer edge-on single photon counting silicon microstrip detector for innovative techniques in diagnostic radiology

A three-layer detector prototype, obtained by stacking three edge-on single photon counting silicon microstrip detectors, has been developed and widely tested. This was done in the framework of the Synchrotron Radiation for Medical Physics/Frontier Radiology (SYRMEP/FRONTRAD) collaboration activities, whose aim is to improve the quality of mammographic examinations operating both on the source and on the detector side. The active surface of the device has been fully characterized making use of an edge-scanning technique and of a well-collimated laminar synchrotron radiation beam. The obtained data (interlayer distances, channel correspondence, etc.) have then been used to combine information coming from each detector layer, without causing any loss in spatial and contrast resolution of the device. Contrast and spatial resolution have also been separately evaluated for each detector layer. Moreover, imaging techniques (phase contrast, refraction, and scatter imaging), resulting in an increased visibility of low absorbing details, have been implemented, and their effectiveness has been tested on a biological sample. Finally, the possibility of simultaneously acquiring different kind of images with the different detector layers is discussed. This would result in maximizing the information extracted from the sample, while at the same time the high absorption efficiency of the detector device would allow a low dose delivery

Optimal monetary policy and fiscal policy interaction in a non-Ricardian Economy

This paper studies optimal discretionary monetary policy and its interaction with fiscal policy in a New Keynesian model with finitely-lived consumers and gov- ernment debt. Optimal discretionary monetary policy involves debt stabilization to reduce consumption dispersion across cohorts of consumers. The welfare relevance of debt stabilization is proportional to the debt-to-output ratio and inversely related to the household's probability of survival that a¤ects the household's propensity to consume out financial wealth. Debt stabilization bias implies that discretionary optimal policy is suboptimal compared with the inflation targeting rule that fully stabilizes the output gap and the inflation rate while leaving debt to freely fluctuate in response to demand shocks