Geometrical aspects of integrable systems

We review some basic theorems on integrability of Hamiltonian systems, namely the Liouville-Arnold theorem on complete integrability, the Nekhoroshev theorem on partial integrability and the Mishchenko-Fomenko theorem on noncommutative integrability, and for each of them we give a version suitable for the noncompact case. We give a possible global version of the previous local results, under certain topological hypotheses on the base space. It turns out that locally affine structures arise naturally in this setting.Comment: It will appear on International Journal of Geometric Methods in Modern Physics vol.5 n.3 (May 2008) issu

Hybrid Optical Switching for Data Center Networks

Current data centers networks rely on electronic switching and point-to-point interconnects.When considering future data center requirements, these solutions will raise issues in terms of flexibility, scalability, performance, and energy consumption. For this reason several optical switched interconnects, which make use of optical switches and wavelength division multiplexing (WDM), have been recently proposed. However, the solutions proposed so far suffer from low flexibility and are not able to provide service differentiation. In this paper we introduce a novel data center network based on hybrid optical switching (HOS). HOS combines optical circuit, burst, and packet switching on the same network. In this way different data center applications can be mapped to the optical transportmechanism that best suits their traffic characteristics. Furthermore, the proposed HOS network achieves high transmission efficiency and reduced energy consumption by using two parallel optical switches. We consider the architectures of both a traditional data center network and the proposed HOS network and present a combined analytical and simulation approach for their performance and energy consumption evaluation. We demonstrate that the proposed HOS data center network achieves high performance and flexibility while considerably reducing the energy consumption of current solutions

Assessment of Identity Disturbance: Factor Structure and Validation of the Personality Structure Questionnaire in an Italian Sample

here are few brief measures of identity disturbance for use in clinical practice that have been subject to any cross - culturally validation . This study investigated the construct validity of the Personality Structure Questionnaire (PSQ) in Italian clinical (N=237) and community ( N=296) samples . Confirmatory factor analysis was conducted to investigate the internal structure of the PSQ. A three – factor structure (i.e., differing self - states, mood variability and behavioral loss of control) including a second - order factor provided the best fit to the data . This structure was demonstrated to be invariant across sex and clinical diagnosis , with clinical diagnosis significantly predicting increased PSQ scores . A g lobal PSQ score of between 26 - 28 was found to be an appropriate cut-off for assisting in diagnostic processes. Implications for the assessment and treatment of psychological disorders with a marked identity disturbance component are discussed

Exchange bias effect in the phase separated Nd_{1-x}Sr_{x}CoO_3 at the spontaneous ferromagnetic/ferrimagnetic interface

We report the new results of exchange bias effect in Nd_{1-x}Sr_{x}CoO_3 for x = 0.20 and 0.40, where the exchange bias phenomenon is involved with the ferrimagnetic (FI) state in a spontaneously phase separated system. The zero-field cooled magnetization exhibits the FI (T_{FI}) and ferromagnetic (T_C) transitions at ~ 23 and \sim 70 K, respectively for x = 0.20. The negative horizontal and positive vertical shifts of the magnetic hysteresis loops are observed when the system is cooled through T_{FI} in presence of a positive static magnetic field. Training effect is observed for x = 0.20, which could be interpreted by a spin configurational relaxation model. The unidirectional shifts of the hysteresis loops as a function of temperature exhibit the absence of exchange bias above T_{FI} for x = 0.20. The analysis of the cooling field dependence of exchange bias field and magnetization indicates that the ferromagnetic (FM) clusters consist of single magnetic domain with average size around \sim 20 and ~ 40 \AA ~ for x = 0.20 and 0.40, respectively. The sizes of the FM clusters are close to the percolation threshold for x = 0.20, which grow and coalesce to form the bigger size for x = 0.40 resulting in a weak exchange bias effect.Comment: 9 pages, 9 figure

The bridge volcanic LIdar-BILLI: A review of data collection and processing techniques in the Italian most hazardous volcanic areas

Volcanologists have demonstrated that carbon dioxide (CO2) fluxes are precursors of volcanic eruptions. Controlling volcanic gases and, in particular, the CO2 flux, is technically challenging, but we can retrieve useful information from magmatic/geological process studies for the mitigation of volcanic hazards including air traffic security. Existing techniques used to probe volcanic gas fluxes have severe limitations such as the requirement of near-vent in situ measurements, which is unsafe for operators and deleterious for equipment. In order to overcome these limitations, a novel range-resolved DIAL-Lidar (Differential Absorption Light Detection and Ranging) has been developed as part of the ERC (European Research Council) Project "BRIDGE", for sensitive, remote, and safe real-time CO2 observations. Here, we report on data collection, processing techniques, and the most significant findings of the experimental campaigns carried out at the most hazardous volcanic areas in Italy: Pozzuoli Solfatara (Phlegraen Fields), Stromboli, and Mt. Etna. The BrIdge voLcanic LIdar-BILLI has successfully obtained accurate measurements of in-plume CO2 concentration and flux. In addition, wind velocity has also been retrieved. It has been shown that the measurements of CO2 concentration performed by BILLI are comparable to those carried out by volcanologists with other standard techniques, heralding a new era in the observation of long-term volcanic gases

Ambulatory surgery for perianal Crohn’s disease. Study of feasibility

Background. One-third of Crohn’s disease (CD) patients present perianal fistula. The gold standard in the diagnosis and treatment of symptomatic perianal disease (PAD) in CD is the exploration of the anal canal and distal rectum under anesthesia (EUA). This procedure is mainly conducted as a day case surgery. Unfortunately, it is not always possible to proceed within the ideal timing and any delay may well represent a relevant clinical issue. The aim of this study was to evaluate the feasibility of outpatient treatment of symptomatic perianal fistulas in CD patients. Methods. All CD patients under regular follow-up at our inflammatory bowel disease referral center, presenting with symptomatic perianal fistulas, were offered surgical consultation. The data of patients were prospectively collected for three years (February 2014 to February 2017) for the purpose of the study. All clinical information, including previous EUA and/or records from MRI and endoscopic ultrasound, was included. Outpatient anal canal and distal rectum exploration and treatment (OE) were undertaken during the specialist surgical consultation. Fistulas were classified according to Parks’s classification; the type of outpatient treatment and compliance of patients were recorded. Pain was assessed by VAS at the time of the procedure and during the first control. Patients were followed up in the surgical clinic in relation to the study. Results. Ninety-two CD patients with symptomatic perianal fistulas had surgical consultation during the study period. OE was offered to all but 18 patients who fulfilled the exclusion criteria or had an extremely severe disease; six patients refused the OE (8.11%). Of the 68 patients undergoing OE, eleven (16.18%) had previous surgery for perianal disease. The OE was accomplished in sixty-one patients (89.71%), while in 7 patients, it was abandoned for scarce compliance. Nine patients (14.75%) underwent drainage of perianal abscess; in 3 of them, it was possible to probe the fistula tract, find the internal orifice, and pass a loose seton. Overall, setonage was performed in 50 patients (81.97%). Rectovaginal setons were placed in 3 patients and more than one seton (up to 3) in 6 cases. Fistulotomy was performed in 4 simple subcutaneous fistulous tracts. Concordance with the preoperative findings was found in 54 out of 61 patients. EUA was scheduled at the time of OE for the 7 patients who did not complete the procedure. All sixty-one patients who had the OE were followed up for a minimum of 12 months. Conclusions. This preliminary study indicates that OE in CD patients with symptomatic perianal fistulas is safe and feasible in a high-volume referral center. It might provide several benefits, including patients’ logistics, reduce or remove patients’ symptoms and discomfort, allow for a timely start of medical therapy, and avoid further complications

Magnetic properties of the frustrated AFM spinel ZnCr_2O_4 and the spin-glass Zn_{1-x}Cd_xCr_2O_4 (x=0.05,0.10)

The $T$-dependence (2- 400 K) of the electron paramagnetic resonance (EPR), magnetic susceptibility, $\chi (T)$, and specific heat, $C_{v}(T)$, of the $normal$ antiferromagnetic (AFM) spinel ZnCr$_{2}$O$_{4}$ and the spin-glass (SG) Zn$_{1-x}$Cd$_{x}$Cr$_{2}$O$_{4}$ ($x=0.05,0.10$) is reported. These systems behave as a strongly frustrated AFM and SG with $$ $\approx T_{G}\approx 12$ K and -400 K $\gtrsim \Theta_{CW}\gtrsim -500$ K. At high-$T$ the EPR intensity follows the $\chi (T)$ and the $g$-value is $T$-independent. The linewidth broadens as the temperature is lowered, suggesting the existence of short range AFM correlations in the paramagnetic phase. For ZnCr$_{2}$O$_{4}$ the EPR intensity and $\chi (T)$ decreases below 90 K and 50 K, respectively. These results are discussed in terms of nearest-neighbor Cr$^{3+}$ (S $=3/2$%) spin-coupled pairs with an exchange coupling of $| J/k| \approx$ 50 K. The appearance of small resonance modes for $T\lesssim 17$ K, the observation of a sharp drop in $\chi (T)$ and a strong peak in $C_{v}(T)$ at $T_{N}=12$ K confirms, as previously reported, the existence of long range AFM correlations in the low-$T$ phase. A comparison with recent neutron diffraction experiments that found a near dispersionless excitation at 4.5 meV for $T\lesssim T_{N}$ and a continuous gapless spectrum for $T\gtrsim T_{N}$, is also given.Comment: 17 pages, 8 figures, 1 Table. Submitted to Physical Review

Particle size dependence of the magnetic properties of ultrafine granular films

Magnetic granular solids consist of ultrafine metal granules of nanometer sizes embedded in an insulating medium. The magnetic properties are dictated by the microstructure such as particle size, metal volume fraction, which are process controlled. We report the results of a series of granular Fe60(SiO2)40 films in which the particle size has been systematically varied. The magnetic coercivity, ranging from 500 to 2200 Oe, increases with particle size. The ferromagnetic-superparamagnetic transition had been studied by SQUID magnetometry and Mössbauer spectroscopy. The value of the magnetic anisotropy energy is found to be much larger than that due to magnetocrystalline anisotropy

Unusual enhancement of effective magnetic anisotropy with decreasing particle size in maghemite nanoparticles

In magnetic nanoparticles (NPs), the observed increase in the effective magnetic anisotropy Keff with the decrease in particle size D is often interpreted, sometimes unsuccessfully, using the equation Keff = Kb + (6KS/D), where Kb is the bulk-like anisotropy of the core spins and KS is the anisotropy of spins in the surface layer. Here, we test the validity of this relation in γ-Fe2O3 NPs for sizes D from 15 nm to 2.5 nm. The samples include oleic acid-coated NPs with D = 2.5, 3.4, 6.3, and 7.0 nm investigated here, with results on 14 other sizes taken from literature. Keff is determined from the analysis of the frequency dependence of the blocking temperature TB after considering the effects of interparticle interactions on TB. For the γ-Fe2O3 NPs with D \u3c 5 nm, an unusual enhancement of Keff with decreasing D, well above the magnitudes predicted by the above equation, is observed. Instead the variation of Keff vs. D is best described by an extension of the above equation by including Ksh term from spins in a shell of thickness d. Based on this core-shell-surface layer model, the data are fit to the equation Keff = Kb + (6KS/D) + Ksh{[1−(2d/D)]−3−1} with Kb = 1.9 × 105 ergs/cm3, KS = 0.035 ergs/cm2, and Ksh = 1.057 × 104 ergs/cm3 as the contribution of spins in the shell of thickness d = 1.1 nm. Significance of this result is discussed