Equivalence of Bose-Einstein condensation and symmetry breaking

Based on a classic paper by Ginibre [Commun. Math. Phys. {\bf 8} 26 (1968)] it is shown that whenever Bogoliubov's approximation, that is, the replacement of a_0 and a_0^* by complex numbers in the Hamiltonian, asymptotically yields the right pressure, it also implies the asymptotic equality of ||^2/V and /V in symmetry breaking fields, irrespective of the existence or absence of Bose-Einstein condensation. Because the former was proved by Ginibre to hold for absolutely integrable superstable pair interactions, the latter is equally valid in this case. Apart from Ginibre's work, our proof uses only a simple convexity inequality due to Griffiths.Comment: An error in my summary of previous results (the definition of F') is corrected. The correction is to be done also in the PR

Heat Transport in Mesoscopic Systems

Phonon heat transport in mesoscopic systems is investigated using methods analogous to the Landauer description of electrical conductance. A "universal heat conductance" expression that depends on the properties of the conducting pathway only through the mode cutoff frequencies is derived. Corrections due to reflections at the junction between the thermal body and the conducting bridge are found to be small except at very low temperatures where only the lowest few bridge modes are excited. Various non-equilibrium phonon distributions are studied: a narrow band distribution leads to clear steps in the cooling curve, analogous to the quantized resistance values in narrow wires, but a thermal distribution is too broad to show such features.Comment: To be published in Superlattices and Microstructures, special issue in honor of Rolf Landauer, March 198

Stone in a paracaliceal diverticula managed percutaneously

Introduction: Percutaneous technique of stone removal from a paracaliceal diverticula is presented. Materials and Methods: Paracaliceal diverticula is not a frequent finding. It is associated with narrow communication of the calyx with renal pelvis. Sometime the caliceal communication is angulated which interfere with ESWL management. Until recently, such cases were treated by open surgery. Results: After percutaneously stone removal and repunction in the renal pelvis, a large nephrostomy was maintained for thirty days, transforming the diverticula in a new calyx. After nephrostomy removal, "double J» stent was kept in the urether for two weeks. Conclusions: The percutaneously management of stones in paracaliceal diverticula is accepted as a minimally invasive technique with good results, in hands of an skilled endoscopist

Bilateral staghorn cystinic calculi managed percutaneously

Introduction: The results of percutaneous management of bilateral staghorn cystinic calculi is presented. Materials and Methods: 1 - 4% of all urinary lithiasis is chemically cystinic (1/20.000 population). Usually open surgery is the first choice because of the particulary hardness of this type of stone. The staghorn calculi were removed percutaneously, in series, bilateral. Results: Few small fragments of calculi were abandoned in the right lower calyx and removed several months later. The patient was seen every year for the last three years - no recurrence. Conclusions: Percutanoeus management of cystinic stagorn calculi is shown as an alternative to open surgery

The endoscopic resection in two surgery steps - therapeutic solution in peculiar BPH cases

Objective: The two steps endoscopic resection for BPH can be from the beginning indicated (great adenomas) or imposed during resection (intra-operative or anaesthetic complications or incidents). Material and Methods: Out of 7500 TUR-P done during 1983 - 2000 in our center, from which 57 cases of prostatic adenomas were endoscopic resected in two steps (at maximum of 7 days from the first intervention). This kind of surgical intervention was settled from the beginning in 5 cases (10,6%>), and for the rest it was imposed by the intra-operative complications. Results: The TUR-P intervention in two steps was performed in 5 cases with great adenoma where classical operation was not indicated due to associated organics problems (especially severe respiratory dysfunction, marked obesity, etc), when was respected one lobe and after around one week the operation was ended. For the rest of 52 cases the endoscopic resection had to be stopped because of intra-operative massive bleeding (12 cases), trigonal submination (5 cases), anaesthetical accidents (17 cases) and cardio-vascular balance accidents (18 cases). Conclusions: The endoscopic resection in two steps solved in better conditions patients with prostatic adenomas comparative to an incomplete resection, which would have stressed the symptomatology and complications of those patients

A Droplet within the Spherical Model

Various substances in the liquid state tend to form droplets. In this paper the shape of such droplets is investigated within the spherical model of a lattice gas. We show that in this case the droplet boundary is always diffusive, as opposed to sharp, and find the corresponding density profiles (droplet shapes). Translation-invariant versions of the spherical model do not fix the spatial location of the droplet, hence lead to mixed phases. To obtain pure macroscopic states (which describe localized droplets) we use generalized quasi-averaging. Conventional quasi-averaging deforms droplets and, hence, can not be used for this purpose. On the contrary, application of the generalized method of quasi-averages yields droplet shapes which do not depend on the magnitude of the applied external field.Comment: 22 pages, 2 figure

A microfluidic technique for generating monodisperse submicron-sized drops

International audienceWe present a route for producing monodisperse micro and nanodrops that is based on a liquid-gas phase transition occurring within a microfluidic device. A gas which is soluble in water is mixed with an insoluble one and injected into an aqueous surfactant solution, using a microfluidic device that produces monodisperse bubbles. As the soluble gas diffuses out of the bubbles, they shrink and the remaining insoluble gas condenses into drops. Their radius can be tuned over a wide range by changing the initial gas mixing ratio

Low-temperature heat transfer in nanowires

The new regime of low-temperature heat transfer in suspended nanowires is predicted. It takes place when (i) only ``acoustic'' phonon modes of the wire are thermally populated and (ii) phonons are subject to the effective elastic scattering. Qualitatively, the main peculiarities of heat transfer originate due to appearance of the flexural modes with high density of states in the wire phonon spectrum. They give rise to the $T^{1/2}$ temperature dependence of the wire thermal conductance. The experimental situations where the new regime is likely to be detected are discussed.Comment: RevTex file, 1 PS figur