Bubble-nucleation rates for cosmological phase transitions

We estimate bubble-nucleation rates for cosmological phase transitions. We concentrate on the evaluation of the pre-exponential factor, for which we give approximate analytical expressions. Our approach relies on the use of a real coarse-grained potential. We show how the coarse-graining scale can be determined in the studies of high-temperature phase transitions. We discuss the metastability bound on the Higgs-boson mass and the electroweak phase transition. We find that the saddle-point approximation is reliable in the first case and breaks down in the second case.Comment: 8 pages, 2 fig.s. Final versio

A flexible sensor technology for the distributed measurement of interaction pressure

We present a sensor technology for the measure of the physical human-robot interaction pressure developed in the last years at Scuola Superiore Sant'Anna. The system is composed of flexible matrices of opto-electronic sensors covered by a soft silicone cover. This sensory system is completely modular and scalable, allowing one to cover areas of any sizes and shapes, and to measure different pressure ranges. In this work we present the main application areas for this technology. A first generation of the system was used to monitor human-robot interaction in upper- (NEUROExos; Scuola Superiore Sant'Anna) and lower-limb (LOPES; University of Twente) exoskeletons for rehabilitation. A second generation, with increased resolution and wireless connection, was used to develop a pressure-sensitive foot insole and an improved human-robot interaction measurement systems. The experimental characterization of the latter system along with its validation on three healthy subjects is presented here for the first time. A perspective on future uses and development of the technology is finally drafted

Critical pedagogy and citizenship : Lorenzo Milani and the school of Barbiana

This article can also be found in: Learning and Social Difference, Challenges for Public Education and Critical pedagogy. Boulder, Colorado: Paradigm, 2006. Chapter 8,This paper discusses the pedagogical challenge of providing an education that stresses the connection between learning and power and the potential, for social solidarity, of a collective approach to learning based on a process of what Freire and other critical pedagogues would call ‘critical literacy.’ The stimulus for such a pedagogical approach to citizenship derives from the legacy of a radical and very controversial Tuscan priest, Don Lorenzo Milani (1923-1967), and the students from an isolated and impoverished farming community in the Mugello region of Tuscany who constituted the School of Barbiana. The pedagogical ideas emanating from Lorenzo Milani and his school of Barbiana remain a source of reference in debates about schooling and social activism in Italy and elsewhere. The key text to emerge from this school, Lettera a Una Professoressa (Letter to a Teacher), was an important source of reference during the turbulent ‘sessantotto’ (1968) period in Italy. The paper provides an analysis of this and other works with whihc Lorenzo Milani was connected.peer-reviewe

A Novel Role of Cdk9/CyclinT2 complexes in skeletal muscle and Rhabdomyosarcoma cells

Cyclin dependent kinase 9 (Cdk9) is a member of the cyclin dependent kinase family. The regulatory units of Cdk9 are the T family Cyclins (T1, T2) and Cyclin K1. Cyclin T2 has two forms termed CycT2a and CycT2b that arise by an alternative splicing of the primary transcript. Previous studies underscored a crucial role for Cdk9 in association of Cyclin T2 during skeletal myogenesis. Upon induction of muscle differentiation, MyoD recruits Cdk9/CycT2 on musclespecific gene promoter sequences. This complex is able to phosphorylate the C-terminal domain of RNA polymerase II, enhancing Myod function and promoting myogenic differentiation. Rhabdomyosarcoma (RMS), one of the most common childhood solid tumor, arises from muscle precursor cells and fails to complete both the differentiation program both the irreversibly cell cycle exit, resulting in uncontrolled proliferation and incomplete myogenesis. In RMS, Cdk9 fails to phosphorylate MyoD and the ability of MyoD to arrest cell proliferation and to activate the myogenic program is repressed. The result of this study confirmed the involvement of Cdk9/ CyclinT2 complexes during the myogenesis. Both isoforms of Cyclin T2 are able to activate the myogenic program at different stages of differentiation but CycT2b have a predominant role of in particular during the latest stages. Moreover we demonstred that EZH2 is probably responsible to inhibition of Cdk9 in RMS cells and her overexpression contribuite to inhibition of myogenesis

The slowly variable star FY Lacertae

Photometric observations and analysis of FY Lac were performed in order to determine the variability characteristics, using measurements taken at Loiano site of Bologna Astronomical Observatory and AAVSO data. The star shows a Long Term variability with a preliminary period of about 274 +/- 28 days and photometric characteristics compatible with a red M5 III giant star, with a temperature of 3420 K degrees.Comment: 9 page

On singular Fano varieties with a divisor of Picard number one

In this paper we study the geometry of mildly singular Fano varieties on which there is an effective prime divisor of Picard number one. Afterwards, we address the case of toric varieties. Finally, we treat the lifting of extremal contractions to universal covering spaces in codimension 1.Comment: 35 pages. Final version: to appear in Annali della Scuola Normale Superiore, Classe di Scienz

A Liouville theorem for the Degasperis-Procesi equation

We prove that the only global, strong, spatially periodic solution to the Degasperis-Procesi equation, vanishing at some point (t0, x0), is the identically zero solution. We also establish the analogue of such Liouville-type theorem for the Degasperis-Procesi equation with an additional dispersive term.Comment: Post-refereeing version. To appear on Annali Scienze Scuola Norm. Sup. Pisa. Doi 10.2422/2036-2145.201410\_01

Choosers or losers? Progression from school to lifelong learning in the UK

This paper discusses the relationship between secondary schools and life-long learning as provided by Further Education (FE) colleges in the UK. It argues that this relationship is often problematic, both as a result of prevailing market ideology and of historically-grounded discourses about the relative status of the two sectors. The paper questions the notion that learners transferring to FE a t 16 are exercising a real 'choice'; but also draws attention to evidence that significant numbers of them nevertheless find FE a more engaging and rewarding experience than school