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A Coniglio

Publications and source records attributed to A Coniglio.

At least 19 recordsLinked to original sources
PubMed2001

Slow dynamics and aging in a constrained diffusion model.

We carry out a complete analysis of the schematic diffusive model recently introduced for the description of supercooled liquids and glassy systems above the glass temperature. The model is described by a trivial equilibrium measure and the presence of kinetics constraints is mimicked through a rapidly decreasing mobility at high particle density. The governing equation describing a sudden quench process is investigated analytically in a mean field approach and by means of numerical simulations. For deep quenches a long lasting off-equilibrium dynamics is observed in dense systems before equilibration is achieved, where time translational invariance lacks and the system ages. The kinetics is slow in this time domain since the average particle diffusivity D decreases in time, as opposed to the standard diffusion case of a constant D, that is recovered only in equilibrium. The autocorrelation function decays slower than an exponential, falling in mean field as an enhanced power law. The linear response function is computed and the modalities of the break-down of the fluctuation dissipation theorem are analytically investigated, showing that an effective temperature can be defined which slowly approaches the bath temperature from above.

Journal Article↗
PubMed2000

Suprarenal aortic cross-clamping in elective abdominal aortic aneurysm surgery.

INTRODUCTION: this retrospective study was undertaken to evaluate whether suprarenal aortic cross-clamping increased the perioperative mortality and morbidity as compared to infrarenal clamping, in order to create the rationale for a more extensive application of this apparently more traumatic manoeuvre. MATERIALS AND METHODS: in a series of 734 elective aortic substitutions for abdominal aneurysm (AA), performed consecutively from January 1992 to June 1999, aortic cross-clamping was performed at a suprarenal level in 56 juxtarenal aneurysms, i.e. aneurysms extending to the lower edge of the renal arteries (8%, Group 1), and at an infrarenal level in 634 subrenal aneurysms (92%, Group 2). When analysing preoperative data, the diameter of aneurysms was larger in Group 1 than in Group 2 (p<0. 005). No significant differences were found between the two groups as regards age, sex, postinfarction cardiomyopathy, chronic obstructive pulmonary disease, chronic renal insufficiency and ASA classification of operative risks. RESULTS: the average time of renal exclusion in the juxtarenal aneurysms was 20 min (range 12-35 min). There is no difference between the two groups as regards the time of aortic clamping (mean 50 vs. 60 min) or the need for homologous blood transfusion (7% vs. 11% of patients). Perioperative (30 days) mortality did not differ: 3.6% vs. 1.9% (n.s.); nor did the incidence of acute myocardial infarction (3.6% vs. 2.3%). Renal function deteriorated in 8 (14%) vs. 0 (0%) (p<0.001) and 1 patient (2%) required permanent dialysis, as compared to 0% in Group 2. The incidence of ischaemic colitis was also significantly higher in Group 1 (7%) than in Group 2 (2%, p<0.01). CONCLUSION: this data shows that suprarenal clamping, which is necessary for the radical treatment of juxtarenal aortic aneurysms, can be performed with a low risk.

Aged↗
PubMed2000

Glass transition in the quenched and annealed version of the frustrated lattice gas model

In this paper we study the three-dimensional frustrated lattice gas model in the annealed version, where the disorder is allowed to evolve in time with a suitable kinetic constraint. Although the model does not exhibit any thermodynamic transition it shows a diverging peak at some characteristic time in the dynamical nonlinear susceptibility, similar to the results on the p-spin model in mean field and the Lennard-Jones mixture recently found by Donati et al. (e-print cond-mat/9905433). Comparing these results to those obtained in the model with quenched interactions, we conclude that the critical behavior of the dynamical susceptibility is reminiscent of the thermodynamic transition present in the quenched model, and signaled by the divergence of the static nonlinear susceptibility, suggesting therefore a similar mechanism also in supercooled glass-forming liquids.

Journal Article↗
PubMed1995

Surgery for obstructive lesions of the main trunk of the renal artery. A review of the literature and personal experience of 41 operated patients.

Today, surgical revascularization of the renal artery seems to maintain interest in the therapy of renovascular hypertension and chronic ischemic nephropathy because both medical therapy and angioplasty show limits and inconveniences. The authors present here their experience of 45 revascularized renal arteries in 41 patients and they discuss early and late morphological and functional results related to isolated arterial renal pathology (Group 1 of 23 patients) and associated to aorto-iliac pathology (Group 2 of 18 patients). Mortality related to arterial renal reconstruction was nil. There were 3/45 arteries (6.6%) with early thromboses and 4/32 (9.3%) with late thromboses. Early functional results, with respect to renovascular hypertension and/or chronic ischaemic renal insufficiency, showed 16/41 (39%) healed patients, 16/41 (39%) improved patients and 9/41 (22%) unvariated patients. Late results among 28 observed patients (average follow up at 49 months, range from 18 to 144 months) showed 14/28 (50%) healed patients, 11/28 (39%) improved patients and 3/28 (11%) unvariated patients. Results of the Group I were significantly better than results of Group 2 with regards to healed patients (p < 0.01) but not summarizing healed and improved cases. These data have been discussed in comparison with the Literature review of 46 references.

Adult↗