Response of Glass and Liquid Phases in the Vortex lattice to an external AC magnetic field at different frequencies

We individuated a method to distinguish a glass phase from a highly viscous liquid phase in a lattice of vortices, established in type-two superconductors. Our analysis is based on the study of the temperature dependence of numerically obtained 1st and 3rd harmonics curves of the AC magnetic susceptibility, by changing the frequency of the applied AC magnetic field. The harmonics are obtained by integrating the non-linear diffusion equation for the magnetic field, with different voltage-current characteristics, corresponding to the two different phases. This method could be applied to the analysis of experimental curves in order to determine if the detected magnetic response of superconducting samples may be interpreted in terms of vortex glass or Kim-Anderson model.Comment: 6 pages, 5 figures, to be published on Physica

RANKL-RANK-OPG Pathway in Charcot Diabetic Foot: Pathophysiology and Clinical-Therapeutic Implications

Charcot Foot (CF), part of a broader condition known as Charcot Neuro-Osteoarthropathy (CNO), is characterized by neuropathic arthropathy with a progressive alteration of the foot. CNO is one of the most devastating complications in patients with diabetes mellitus and peripheral neuropathy but can also be caused by neurological or infectious diseases. The pathogenesis is multifactorial; many studies have demonstrated the central role of inflammation and the Receptor Activator of NF-kappa B ligand (RANKL)-Receptor Activator of NF-kappa B (RANK)-Osteoprotegerin (OPG) pathway in the acute phase of the disease, resulting in the serum overexpression of RANKL. This overexpression and activation of this signal lead to increased osteoclast activity and osteolysis, which is a prelude to bone destruction. The aim of this narrative review is to analyze this signaling pathway in bone remodeling, and in CF in particular, to highlight its clinical aspects and possible therapeutic implications of targeting drugs at different levels of the pathway. Drugs that act at different levels in this pathway are anti-RANKL monoclonal antibodies (Denosumab), bisphosphonates (BP), and calcitonin. The literature review showed encouraging data on treatment with Denosumab, although in a few studies and in small sample sizes. In contrast, BPs have been re-evaluated in recent years in relation to the high possibility of side effects, while calcitonin has shown little efficacy on CNO

Superconducting Vortex‐Antivortex Pairs: Nucleation and Confinement in Magnetically Coupled Superconductor‐Ferromagnet Hybrids

Superconducting vortices are a well known class of vortices, each of them carrying a single magnetic flux quantum. In this chapter the authors present the results of low temperature Magnetic Force Microscopy experiments to investigate the nucleation and dynamics of superconducting vortices in magnetically coupled Superconductor/Ferromagnet (S/F) heterostructures made by Nb/Py. It is here shown that by controlling the thicknesses of both S and F layer, the formation of spontaneous vortex-antivortex pairs (V-AV) can be favored and their confinement and mobility can be tuned. The experimental results are compared with two theoretical models dealing with the spontaneous nucleation of V/AV pairs in the limits of S thickness respectively greater and smaller than the London penetration depth. It is shown that vortex nucleation and confinement is regulated by the intensity of the out-of-plane component of the magnetization with respect to a critical magnetization set by the thickness of both S and F layers. Additionally, external field cooling processes were used to probe in-field vortex nucleation and V-AV unbalancing, whereas the sweeping of an external magnetic field when below the superconducting critical temperature was used to force the vortex into motion, probing the vortex mobility/rigidity and the vortex avalanche events

Temperature dependence of the surface barrier on YBa2Cu3O7−δ grains detected by AC susceptibility measurements

The surface barrier on YBa2Cu3O7−δ grains has been studied in dynamic regime by performing measurements of the two components of the “Wide-Band” Susceptibility, χa and χr, as function of the applied AC field amplitude at different temperatures and frequencies. The best fit of the measured curves was obtained with the analytical expression of χa and χr calculated from a model in which the magnetic behaviour of the sample is supposed to be governed by the intergrain shielding current and by a surface barrier on the grains of the sample. From the fitting results, the height of the surface barrier on the grains has been valued independently for each measured curve, allowing us to determine the temperature dependence of the surface barrier using an AC technique at different frequencies. The result is a barrier which decreases with increasing temperatures, but its temperature dependence at low (up to about 10 kHz) frequencies of the applied AC field is different respect to the dependencies obtained at higher frequencies

A method and system for identifying an authorized individual by means of unpredictable single-use passwords. Procedimento e sistema per l’identificazione di un soggetto autorizzato in una rete di comunicazione, per mezzo di parole d’ordine monouso non prevedibili

A method is described for the identification of a party authorised to have the benefit of a service delivered by a provider party via a telematics network, in which the provider party and each user party are connected to the network by means of a respective electronic communications and processing system (S, C), and the provider party requests a temporary password (PWD) identifying the user party to allow access to the services delivered. The method is characterised in that it involves autonomous execution of a procedure for calculating the password (PWD) in the processing systems (S, C) of both parties on the basis or predetermined algorithms, the above-mentioned calcultaing procedure comprising the operations of: generating a first string of characters (N30) by means of a first pre-established algorithm (ALGN30), on the basis of a random number (RND) and a hidden dynamic variable (n; p) not transmitted over the network, but obtained by the processing systems (S, C) independently; extracting a second string of characters (N3), a subset of the first string (N30), by means of a second preestablished algorithm (ALGN3), as a function of the hidden dynamic variable (n; p) and of said random number (RND); ; and generating the temporary password (PWD) by means of a third pre-established algorithm (ALGPWD), on the basis of the above-mentioned second string of characters (N3). The authorsed party is identified as a result of the comparison between the password (PWD) calculated by the processing system (S) of the provider party and that calculated by the processing system (C) of the user party, whereby access to the service is permitted if this comparison gives a positive result and otherwise is denied. The password thus obtained may also be used as a single-use key in a system for encrypting all the information exchanged between the authorised user party and the service provider party