Are the school prevention programmes - aimed at de-normalizing smoking among youths - beneficial in the long term? An example from the Smoke Free Class Competition in Italy

Tobacco smoking by young people is of great concern because it usually leads to regular smoking, nicotine addiction and quitting difficulties. Young people "hooked" by tobacco maintain the profits of the tobacco industry by replacing smokers who quit or die. If new generations could be tobacco-free, as supported by tobacco endgame strategies, the tobacco epidemic could end within decades. Smoking prevention programmes for teens are offered by schools with the aim to prevent or delay smoking onset. Among these, the Smoke Free Class Competition (SFC) was widely implemented in Europe. Its effectiveness yielded conflicting results, but it was only evaluated at short/medium term (6 - 18 months). The aim of this study is to evaluate its effectiveness after a longer follow-up (3 to 5 years) in order to allow enough time for the maturing of the students and the internalization of the experience and its contents. Fifteen classes were randomly sampled from two Italian high schools of Bologna province that regularly offered the SFC to first year students; 382 students (174 participating in the SFC and 208 controls) were retrospectively followed-up and provided their "smoking histories". At the end of their last year of school (after 5 years from the SFC), the percentage of students who stated that they were regular smokers was lower among the SFC students than in controls: 13.5% vs 32.9% (p=0.03). From the students' "smoking histories", statistically significant protective ORs were observed for SFC students at the end of 1st and 5th year: 0.42 (95% CI 0.19-0.93) and 0.32 (95% CI 0.11-0.91) respectively. Absence of smokers in the family was also a strongly statistically significant factor associated with being a non-smoker student. These results suggest that SFC may have a positive impact on lowering the prevalence of smoking in the long term (5 years)

The origin of ultra high energy cosmic rays

We briefly discuss some open problems and recent developments in the investigation of the origin and propagation of ultra high energy cosmic rays (UHECRs).Comment: Invited Review Talk at TAUP 2005 (Zaragoza - September 10-14, 2005). 7 page

Relaxation Methods for Mixed-Integer Optimal Control of Partial Differential Equations

We consider integer-restricted optimal control of systems governed by abstract semilinear evolution equations. This includes the problem of optimal control design for certain distributed parameter systems endowed with multiple actuators, where the task is to minimize costs associated with the dynamics of the system by choosing, for each instant in time, one of the actuators together with ordinary controls. We consider relaxation techniques that are already used successfully for mixed-integer optimal control of ordinary differential equations. Our analysis yields sufficient conditions such that the optimal value and the optimal state of the relaxed problem can be approximated with arbitrary precision by a control satisfying the integer restrictions. The results are obtained by semigroup theory methods. The approach is constructive and gives rise to a numerical method. We supplement the analysis with numerical experiments

Infra-Red Stable Supersymmetry in Chern-Simons Theories with Matter and Quenched Disorder

We study Abelian Chern-Simons field theories with matter fields and global SU(N) symmetry in the presence of random weak quenched disorder. In the absence of disorder these theories possess N=2 supersymmetric fixed points and N=1 supersymmetric fixed lines in the infra-red limit. We show that although the presence of disorder forbids any supersymmetry of the bare action, infra-red stable supersymmetric fixed points and fixed lines are realized in the disorder-averaged effective theories.Comment: 8 pp., LaTeX. Explanatory remarks and references added. Version to appear in Phys. Rev. Let

Topological Vector Symmetry of BRSTQFT and Construction of Maximal Supersymmetry

The scalar and vector topological Yang-Mills symmetries determine a closed and consistent sector of Yang-Mills supersymmetry. We provide a geometrical construction of these symmetries, based on a horizontality condition on reducible manifolds. This yields globally well-defined scalar and vector topological BRST operators. These operators generate a subalgebra of maximally supersymmetric Yang-Mills theory, which is small enough to be closed off-shell with a finite set of auxiliary fields and large enough to determine the Yang-Mills supersymmetric theory. Poincar\'e supersymmetry is reached in the limit of flat manifolds. The arbitrariness of the gauge functions in BRSTQFTs is thus removed by the requirement of scalar and vector topological symmetry, which also determines the complete supersymmetry transformations in a twisted way. Provided additional Killing vectors exist on the manifold, an equivariant extension of our geometrical framework is provided, and the resulting "equivariant topological field theory" corresponds to the twist of super Yang-Mills theory on Omega backgrounds.Comment: 50 page