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J Koltai

Publications and source records attributed to J Koltai.

3 recordsLinked to original sources

Nonparasitic splenic cysts in children: a multicentric study.

PURPOSE: Nonparasitic splenic cysts (NPSCs) are uncommon in children. The aim of this multinational and multicentric study was to present the authors' experience as well as the changing trends in the management of NPSCs over the last 25 years. MATERIAL AND METHODS: From 1981 to 2005, 50 children or adolescents were surgically treated for NPSCs in 6 paediatric surgical centres in four European countries. The medical records of these 50 patients with NPSCs were reviewed retrospectively. RESULTS: Twenty-six male and 24 female patients were operated on. Age at surgery ranged from 1 to 17 years (mean 11.9). Seventeen patients were symptomatic. Six total (4 open and 2 laparoscopic) and 26 partial (22 open and 4 laparoscopic) splenectomies were performed. Laparoscopic fenestration or deroofing and open cystectomy was carried out in 9 patients, respectively. Histological findings revealed the lesion to be an epidermoid cyst (n = 28), a pseudocyst (n = 15) or a mesothelial cyst (n = 2). In 5 patients haemangioma or lymphangioma was the pathological diagnosis. At a mean follow-up of 2.9 years, residual cysts were found in 8 laparoscopically treated patients, 4 of whom required re-do laparoscopy or open surgery. CONCLUSIONS: Over the last two decades, the surgical treatment of NPSCs has changed from a formerly customary total splenectomy to spleen-conserving procedures, such as total cystectomy with or without partial splenectomy or partial cystectomy. These therapeutic modalities can be performed laparoscopically, if technically possible. Fenestration or deroofing of the cyst resulted in a high recurrence rate (7/9).

Adolescent↗

Proximity-induced subgaps in andreev billiards.

We examine the density of states of an Andreev billiard and show that any billiard with a finite upper cutoff in the path length distribution P(s) will possess an energy gap on the scale of the Thouless energy. An exact quantum mechanical calculation for different Andreev billiards gives good agreement with the semiclassical predictions when the energy dependent phase shift for Andreev reflections is properly taken into account. Based on this new semiclassical Bohr-Sommerfeld approximation of the density of states, we derive a simple formula for the energy gap. We show that the energy gap, in units of Thouless energy, may exceed the value predicted earlier from random matrix theory for chaotic billiards.

Journal Article↗

Negative length orbits in normal-superconductor billiard systems

The path-length spectra of mesoscopic systems including diffractive scatterers and connected to a superconductor are studied theoretically. We show that the spectra differ fundamentally from that of normal systems due to the presence of Andreev reflection. It is shown that negative path lengths should arise in the spectra as opposed to the normal system. To highlight this effect we carried out both quantum mechanical and semiclassical calculations for the simplest possible diffractive scatterer. The most pronounced peaks in the path-length spectra of the reflection amplitude are identified by the routes that the electron and/or hole travels.

Journal Article↗