The role of percutaneous nephrolithotomy in the management of medium-sized (1-2 cm) lower-pole renal calculi.

OBJECTIVES: The objective of this study was to determine the efficacy (defined by stone-free rates) and safety of percutaneous nephrolithotomy (PNL) in the treatment of medium sized (1-2 cm) symptomatic lower pole renal calculi, and establishment of the short-term morbidity. METHODS: We performed a retrospective analysis of 60 evaluable patients who had undergone PNL for 1 to 2 cm diameter lower-pole (LP) stones between November 2006 to March 2009 and compared these results with other treatment modalities in published literature. RESULTS: In all cases, stones were located in the lower calix. Thirty-six procedures were performed on the left side, and 24 were performed on the right side. The mean time to access the collecting system was 20.4 minutes (range 8-70 min) and mean operative time was 62.2 minutes (range 13-155 min). Abdominal radiography performed on postoperative day 1 demonstrated a stone free status in 56 (93.3%) patients. However, 4 patients (6.7%) required ancillary procedures (secondary PNL in 1, retrograde intrarenal surgery in 1, and SWL in 2). After this secondary procedures a complete stone-free status was achieved in 98.3% of patients. The morbidity of patients undergoing PNL at our hospital was minimal, with a mean hospital stay of 3.7 days. CONCLUSIONS: We demonstrated that, PNL is a safe and effective method for medium sized (1 to 2 cm) lower pole renal calculi and percutaneous removal should be considered the primary approach for lower pole stones greater than 10 mm.

Towards multimaterial multifunctional fibres that see, hear, sense and communicate.

Virtually all electronic and optoelectronic devices necessitate a challenging assembly of conducting, semiconducting and insulating materials into specific geometries with low-scattering interfaces and microscopic feature dimensions. A variety of wafer-based processing approaches have been developed to address these requirements, which although successful are at the same time inherently restricted by the wafer size, its planar geometry and the complexity associated with sequential high-precision processing steps. In contrast, optical-fibre drawing from a macroscopic preformed rod is simpler and yields extended lengths of uniform fibres. Recently, a new family of fibres composed of conductors, semiconductors and insulators has emerged. These fibres share the basic device attributes of their traditional electronic and optoelectronic counterparts, yet are fabricated using conventional preform-based fibre-processing methods, yielding kilometres of functional fibre devices. Two complementary approaches towards realizing sophisticated functions are explored: on the single-fibre level, the integration of a multiplicity of functional components into one fibre, and on the multiple-fibre level, the assembly of large-scale two- and three-dimensional geometric constructs made of many fibres. When applied together these two approaches pave the way to multifunctional fabric systems.

Tight-binding description of the coupled defect modes in three-dimensional photonic crystals

We have experimentally observed the eigenmode splitting due to coupling of the evanescent defect modes in three-dimensional photonic crystals. The splitting was well explained with a theory based on the classical wave analog of the tight-binding (TB) formalism in solid state physics. The experimental results were used to extract the TB parameters. A new type of waveguiding in a photonic crystal was demonstrated experimentally. A complete transmission was achieved throughout the entire waveguiding band. We have also obtained the dispersion relation for the waveguiding band of the coupled periodic defects from the transmission-phase measurements and from the TB calculations.