METEOROLOGICAL FEATURES OF EXTREME PRECIPITATION IN THE NORTHERN ADRIATIC

An investigation of extreme precipitation cases in the northern Adriatic area is discussed in this paper. The criterion chosen for an extreme event recognition is a measured daily precipitation amount exceeding 100 mm day-1. In the 19912000 period, 18 extreme precipitation events were observed at six meteorological stations in the northern Adriatic and its hinterland. The analysis shows that heavy precipitation occurs most frequently during the autumn season, although it can develop during the other seasons as well. The large-scale examination performed indicates that heavy precipitation events in the northern Adriatic typically occur under the influence of a deep upper-level trough over western Europe, associated with a low south of the Alps, as shown by the calculated mean charts. This kind of synoptic structure generates a southerly warm and moist low-level flow over the Adriatic Sea, favouring precipitation formation which, in case of larger-scale conditional and potential instability, can lead to intense precipitation events. Two cases of particular interest were chosen for the mesoscale analysis. In the first case, on 25 December 2000, intense precipitation was both stratiform and convective, while in the second case, on 16/17 September 2000, it was mainly convective. The case studies show that the specific northern Adriatic orography with steep coastal mountain ridges played a major role both in generating prefrontal orogenic precipitation and in intensifying frontal precipitation. In such an unstably stratified environment, the lifting of moist air over the barrier was accompanied by deep convection development in some places

On the Machine Learning Techniques for Side-channel Analysis

Side-channel attacks represent one of the most powerful category of attacks on cryptographic devices with profiled attacks in a prominent place as the most powerful among them. Indeed, for instance, template attack is a well-known real-world attack that is also the most powerful attack from the information theoretic perspective. On the other hand, machine learning techniques have proven their quality in a numerous applications where one is definitely side-channel analysis, but they come with a price. Selecting the appropriate algorithm as well as the parameters can sometimes be a difficult and time consuming task. Nevertheless, the results obtained until now justify such an effort. However, a large part of those results use simplification of the data relation from the one perspective and extremely powerful machine learning techniques from the other side. In this paper, we concentrate first on the tuning part, which we show to be of extreme importance. Furthermore, since tuning represents a task that is time demanding, we discuss how to use hyperheuristics to obtain good results in a relatively short amount of time. Next, we provide an extensive comparison between various machine learning techniques spanning from extremely simple ones ( even without any parameters to tune), up to methods where previous experience is a must if one wants to obtain competitive results. To support our claims, we give extensive experimental results and discuss the necessary conditions to conduct a proper machine learning analysis. Besides the machine learning algorithms' results, we give results obtained with the template attack. Finally, we investigate the influence of the feature (in)dependence in datasets with varying amount of noise as well as the influence of feature noise and classification noise. In order to strengthen our findings, we also discuss provable machine learning algorithms, i.e., PAC learning algorithms

New Dipole Penguin Contribution to K --> pi pi decays

We point out that the standard chromomagnetic penguin dipole operator has a counterpart corresponding to off-shell momenta for external quarks. By employing the chiral quark model, we show that this new dipole penguin operator has the same bosonisation as the standard Q_6 operator. Accordingly, this new operator enlarges by ~ 5 % the referent Q_6 contribution, which gives the dominant contribution to the CP-violating ratio epsilon'/epsilon and also gives an important contribution to the Delta I = 1/2 amplitude.Comment: 17 pages, 1 PS figure, LaTeX, corresponds to published versio

The double radiative annihilation of the heavy-light fermion bound states

We consider the double-radiative decays of heavy-light QED and QCD atoms, $\mu^+ e^- \to \gamma\gamma$ and $\bar{B}^{0}_s \to \gamma\gamma$. Especially, we take under scrutiny contributions coming from operators that vanish on the free-quark mass shell. We show that by field redefinitions these operators are converted into contact terms attached to the bound state dynamics. A net off-shell contribution is suppressed with respect to the effect of the well known flavour-changing magnetic-moment operator by the bound-state binding factor. The negligible off-shellness of the weakly bound QED atoms becomes more relevant for strongly bound QCD atoms. We analyze this off-shellness in model-approaches to QCD, one of them enabling us to keep close contact to the related effect in QED. We also comment on the off-shell effect in the corresponding process $\bar{B}_d \to K^* \gamma$, and discuss possible hindering of the claimed beyond-standard-model discovery in this decay mode.Comment: 24 pages, 5 figures; to be published in Fizika