Phase ordering with a global conservation law: Ostwald ripening and coalescence

Globally conserved phase ordering dynamics is investigated in systems with short range correlations in the initial condition. A Ginzburg-Landau equation with a global conservation law is employed as the phase field model. The conditions are found under which the sharp-interface limit of this equation is reducible to the area-preserving motion by curvature. Numerical simulations show that, for both critical and off-critical quench, the equal time pair correlation function exhibits dynamic scaling, and the characteristic coarsening length obeys a power law in time with a 1/2 exponent. For the critical quench, our results are in excellent agreement with earlier results. For off-critical quench (Ostwald ripening) we investigate the dynamics of the size distribution function of the minority phase domains. The simulations show that, at large times, this distribution function has a self-similar form with growth exponent 1/2. The scaled distribution, however, strongly differs from the classical Wagner distribution. We attribute this difference to coalescence of domains. A new theory of Ostwald ripening is developed that takes into account binary coalescence events. The theoretical scaled distribution function agrees very well with that obtained in the simulations.Comment: 20 pages, 7 figures, more details adde

Phase field theory of crystal nucleation in hard sphere liquid

The phase field theory of crystal nucleation described in [L. Granasy, T. Borzsonyi, T. Pusztai, Phys. Rev. Lett. 88, 206105 (2002)] is applied for nucleation in hard--sphere liquids. The exact thermodynamics from molecular dynamics is used. The interface thickness for phase field is evaluated from the cross--interfacial variation of the height of the singlet density peaks. The model parameters are fixed in equilibrium so that the free energy and thickness of the (111), (110), and (100) interfaces from molecular dynamics are recovered. The density profiles predicted without adjustable parameters are in a good agreement with the filtered densities from the simulations. Assuming spherical symmetry, we evaluate the height of the nucleation barrier and the Tolman length without adjustable parameters. The barrier heights calculated with the properties of the (111) and (110) interfaces envelope the Monte Carlo results, while those obtained with the average interface properties fall very close to the exact values. In contrast, the classical sharp interface model considerably underestimates the height of the nucleation barrier. We find that the Tolman length is positive for small clusters and decreases with increasing size, a trend consistent with computer simulations.Comment: 7 pages, 7 figure

Cognitive dysfunction improves in systemic lupus erythematosus: Results of a 10 years prospective study

Objective Cognitive impairment (CI) has been described in 3–80% of Systemic lupus erythematosus (SLE) patients but only short-term studies evaluated its over-time changes, suggesting that CI is usually a stable finding. We aimed at evaluating the changes of SLE-related CI in a 10-years prospective single center cohort study. Methods We evaluated 43 patients (M/F 5/38; mean age = 45.7±10.1 years; mean disease duration = 230.8±74.3 months) at baseline (T0) and after 10 years (T1). A test battery designed to detect fronto-subcortical dysfunction across five domains (memory, attention, abstract reasoning, executive and visuospatial function) was administered. A global cognitive dysfunction score (GCD) was obtained and associated with clinical and laboratory features. Results Prevalence of CI was 20.9% at T0 and 13.9% at T1 (P = NS). This impairment was prevalently mild at T0 (55.5%) and mild or moderate at T1 (36.3% for both degrees). After 10 years, CI improved in 50% of patients, while 10% worsened. Impaired memory (P = 0.02), executive functions (P = 0.02) and abstract reasoning (P = 0.03) were associated with dyslipidemia at T0. Worsening of visuospatial functions was significantly associated with dyslipidemia and Lupus Anticoagulant (P = 0.04 for both parameters). Finally, GCD significantly correlated with chronic damage measured by SLICC/damage index at T0 (r = 0.3; P = 0.04) and T1 (r = 0.3; P = 0.03). Conclusions For the first time, we assessed CI changes over 10-years in SLE. CI improved in the majority of the patients. Furthermore, we observed an improvement of the overall cognitive functions. These results could suggest that an appropriate management of the disease during the follow-up could be able to control SLE-related CI

Principles of wide bandwidth acoustic detectors and the single-mass DUAL detector

We apply the standard theory of the elastic body to obtain a set of equations describing the behavior of an acoustic Gravitational Wave detector, fully taking into account the 3-dimensional properties of the mass, the readout and the signal. We show that the advantages given by a Dual detector made by two nested oscillators can also be obtained by monitoring two different acoustic modes of the same oscillator, thus easing the detector realization. We apply these concepts and by means of an optimization process we derive the main figures of such a single-mass Dual detector designed specifically for the frequency interval 2-5kHz. Finally we calculate the SQL sensitivity of this detector.Comment: 29 pages, 10 figure

Area-preserving dynamics of a long slender finger by curvature: a test case for the globally conserved phase ordering

A long and slender finger can serve as a simple ``test bed'' for different phase ordering models. In this work, the globally-conserved, interface-controlled dynamics of a long finger is investigated, analytically and numerically, in two dimensions. An important limit is considered when the finger dynamics are reducible to the area-preserving motion by curvature. A free boundary problem for the finger shape is formulated. An asymptotic perturbation theory is developed that uses the finger aspect ratio as a small parameter. The leading-order approximation is a modification of ``the Mullins finger" (a well-known analytic solution) which width is allowed to slowly vary with time. This time dependence is described, in the leading order, by an exponential law with the characteristic time proportional to the (constant) finger area. The subleading terms of the asymptotic theory are also calculated. Finally, the finger dynamics is investigated numerically, employing the Ginzburg-Landau equation with a global conservation law. The theory is in a very good agreement with the numerical solution.Comment: 8 pages, 4 figures, Latex; corrected typo

Lesioni non palpabili della mammella: la Mammotome-biopsy nella gestione preoperatoria del cancro della mammella

Premessa: Il tumore del seno è nei paesi occidentali al primo posto per frequenza nelle donne e la sua incidenza è in costante crescita. Grazie soprattutto alla diffusione dello screening mammografico e ad una maggiore consapevolezza del problema, negli ultimi anni è aumentata la diagnosi delle cosiddette lesioni “non palpabili”; parimenti si è assistito ad un importante sviluppo delle metodiche diagnostiche di tipo mininvasivo. Alla tradizionale citologia con ago sottile si sono affiancate infatti varie procedure bioptiche percutanee; tali metodiche microistologiche hanno quasi del tutto sostituito la biopsia chirurgica escissionale e l’esame intra-operatorio al congelatore. Pazienti e metodo: Nella nostra Divisione di Chirurgia Generale, Vascolare e Mininvasiva, dal dicembre 1999 al settembre 2004 abbiamo eseguito, in collaborazione con il servizio di Radiologia, 214 biopsie su guida ecografia utilizzando la vacuum-assisted biopsy (Mammotome® ) con ago 11-Gauge. I risultati ottenuti per ciò che concerne l’accuratezza diagnostica, la quantità e qualità delle informazioni ottenute, il significato delle stesse nella eventuale gestione chirurgica, il discomfort globale per la paziente sono stati analizzati e discussi nel presente lavoro. Risultati: Delle 214 biopsie eseguite con tecnica Mammotome, nell’89,3% dei casi si è trattato di lesioni clinicamente non palpabili, con un diametro medio di 8 mm. L’età media delle pazienti era di 57,6 anni (range 31-88). La positività per patologia maligna è stata di 90 casi (42%). Nei casi di iperplasia duttale atipica e radial scar (6%) è stata effettuata l’exeresi chirurgica della lesione che ha confermato nel 100% dei casi la precedente diagnosi bioptica. Il 19% delle pazienti sottoposte a biopsia Mammotome era stato precedentemente sottoposto ad un prelievo citologico con ago sottile. Confrontando i risultati delle due metodiche, l’attendibilità diagnostica della seconda risulta essere significativamente superiore (p<0,05) come pure il numero di informazioni ottenute (istotipo, invasività, grading, recettori ormonali, etc.); il discomfort legato alla procedura, valutato in termini di dolore (VAS), è risultato inferiore a quello del prelievo con ago sottile (p<0,05). L’unica complicanza della biopsia Mammotome è rappresentata dall’ematoma nella sede del prelievo (8% dei casi). Il numero dei falsi negativi è stato di un caso, dovuto ad un non corretto centraggio del bersaglio. Conclusioni: Allo stato attuale in presenza di una lesione non palpabile della mammella la scelta della metodica diagnostica (agobiopsia o Mammotome) è legata al sospetto radiologico nella prospettiva di un eventuale intervento chirurgico. La biopsia con Mammotome nelle lesioni non palpabil