"Root" Action for N=4 Supersymmetric Mechanics Theories

We propose to consider the N=4,d=1 supermultiplet with $% (4,4,0) component content as a ``root'' one. We elaborate a new reduction scheme from the ``root'' multiplet to supermultiplets with a smaller number of physical bosons. Starting from the most general sigma-model type action for the ``root'' multiplet, we explicitly demonstrate that the actions for the rest of linear and nonlinear N=4 supermultiplets can be easily obtained by reduction. Within the proposed reduction scheme there is a natural possibility to introduce Fayet-Iliopoulos terms. In the reduced systems, such terms give rise to potential terms, and in some cases also to terms describing the interaction with a magnetic field. We demonstrate that known N=4 superconformal actions, together with their possible interactions, appear as results of the reduction from a free action for the ``root'' supermultiplet. As a byproduct, we also construct an N=4 supersymmetric action for the linear (3,4,1) supermultiplet, containing both an interaction with a Dirac monopole and a harmonic oscillator-type potential, generalized for arbitrary conformally flat metrics.Comment: 12 page

The April-May 2006 volcano-tectonic events at Stromboli volcano (Southern Italy) and their relation with the magmatic system.

Between April 10th and May 22th 2006, a small seismic swarm of 5 volcano-tectonic events occurred on the volcanic island of Stromboli (Southern Italy). Two of these, having M > 3 and an intensity of about V-VI MCS, were clearly felt causing concern in the population. They were recorded during a period of increased explosive activity and were followed by two major explosions at the summit craters on May 22th, few hours after the last earthquake and on 16th June. The location of such events has been performed using a probabilistic approach based on the Equal Differential Time tecnique. Using this tecnique, we were able to locate all the events, showing how they cluster below the volcanic edifice at a depth of about 5÷6 km. From observed P wave polarities we determined the focal mechanisms of the 4 major events. Using earthquake scaling nlaws, we calculated the fault area and the average slip for the two major events. Finally, assuming an homogeneous half-space model we computed the isotropic stress changes below the volcano edifice. The negative stress variation over the central axis of the volcano suggests that the earthquakes were triggered by a pressurization of the magmatic system

First Order Description of D=4 static Black Holes and the Hamilton-Jacobi equation

In this note we discuss the application of the Hamilton-Jacobi formalism to the first order description of four dimensional spherically symmetric and static black holes. In particular we show that the prepotential characterizing the flow coincides with the Hamilton principal function associated with the one-dimensional effective Lagrangian. This implies that the prepotential can always be defined, at least locally in the radial variable and in the moduli space, both in the extremal and non-extremal case and allows us to conclude that it is duality invariant. We also give, in this framework, a general definition of the ``Weinhold metric'' in terms of which a necessary condition for the existence of multiple attractors is given. The Hamilton-Jacobi formalism can be applied both to the restricted phase space where the electromagnetic potentials have been integrated out as well as in the case where the electromagnetic potentials are dualized to scalar fields using the so-called three-dimensional Euclidean approach. We give some examples of application of the formalism, both for the BPS and the non-BPS black holes.Comment: A clarifying discussion on the existence of the prepotential and a comment on multiple attractors are added; typos corrected, references adde

An experimental and theoretical approach for an estimation of DKth

The existence of a fatigue threshold value may affect the design process when a damage-tolerant design is considered that uses non-destructive techniques for evaluating the shape and dimensions of the defects inside materials. Obviously it should be possible to estimate the stress field surrounding these defects and this is not generally a problem with modern numerical methods.Many factors are involved in determining the growth rate of a fatigue crack. Some of these are highly significant and it is possible to obtain the coefficients of a correlation function. Some others are not well defined and the only effect is to expand the scatter of experimental data.Consider the sigmoidal curve we obtain when plotting the crack growth rate versus the applied DK_I . A very difficult parameter to measure but very useful for fatigue design is the DK_Ith value, because below this value a crack may be forming, hence, here DK_Ith is defined by the transition between a normal (e.g. 10-10 m/cycle) and a very low range of crack growth rate (<10-10 m/cycle).The DgrKIth value is very difficult to obtain by experimental methods because the growth rate is of the order or less than the atomic lattice span (3 × 10-10 m/cycle), but we can correlate the transition value with the cyclic crack tip plastic zone size and other structural parameters of metallic materials.The aim of this work is to offer a contribution about the parameters which influence DK_Ith in stainless steels and welded joints based on the crack tip plastic zone radius

The InfraCyrus infrasound sensor

Infrasound sensors are used for a wide range of geophysical applications as the monitoring of volcanic eruptions, the detection of bolides and the recording of infrasounds generated by earthquakes. In 2006 we started the development of cheap infrasound sensors, based on commercial electret microphones. They have been characterized by comparing their response function with existing broadband infrasound sensors. These sensors, called InfraCyrus, have a good response between 1 and 10 Hz, making their application useful for various geophysical purposes. Currently, about a dozen of sensors are deployed in the Neapolitan area showing good performances in the recording of local and regional infrasonic transients

Effects of anisotropic and isotropic LIPSS on polymer filling flow and wettability of micro injection molded parts

In micro injection molding, the specific cavity surface texture and roughness directly influence the polymer flow and the heat transfer between polymer melt and mold. In this work, two different types of laser-induced periodic surface structures, linear and hexagonal, were generated, and their impact on the flow length in micro injection molding was evaluated. A complete investigation of the surface treatment effect on the polymer flow was carried out, comparing the performance of an untreated cavity surface with surfaces modified by LIPSS. The phenomenon was examined by localizing the weld lines created by the polymer flowing in two parallel channels having different surface treatments. Several cavity inserts were treated by varying the LIPSS process parameters to generate surfaces with different micro-and nanostructures directions and periodicity. Furthermore, the paper addresses the hydro-phobicity achieved on the micro molded surfaces replicated from mold inserts with different LIPSS-based surface topography. Mold surfaces with linear and hexagonal LIPSS and the respective molded parts were analyzed by optical profilometry and scanning electron microscopy to characterize the cavity surfaces replication and localize the weld lines on the micro injection molded parts

Multi-time delay, multi-point Linear Stochastic Estimation of a cavity shear layer velocity from wall-pressure measurements

Multi-time-delay Linear Stochastic Estimation (MTD-LSE) technique is thoroughly described, focusing on its fundamental properties and potentialities. In the multi-time-delay ap- proach, the estimate of the temporal evolution of the velocity at a given location in the flow field is obtained from multiple past samples of the unconditional sources. The technique is applied to estimate the velocity in a cavity shear layer flow, based on wall-pressure measurements from multiple sensor

Thermographic Imaging in Cultural Heritage: A Short Review

Over the recent period, there has been an increasing interest in the use of pulsed infrared thermography (PT) for the non-destructive evaluation of Cultural Heritage (CH). Unlike other techniques that are commonly employed in the same field, PT enables the depth-resolved detection of different kinds of subsurface features, thus providing helpful information for both scholars and restorers. Due to this reason, several research activities are currently underway to further improve the PT effectiveness. In this manuscript, the specific use of PT for the analysis of three different types of CH, namely documentary materials, panel paintings–marquetery, and mosaics, will be reviewed. In the latter case, i.e., mosaics, passive thermography combined with ground penetrating radar (GPR) and digital microscopy (DM) have also been deepened, considering their suitability in the open field. Such items have been selected because they are characterized by quite distinct physical and structural properties and, therefore, different PT (and, in some cases, verification) approaches have been employed for their investigations