Radiographic surveillance of minimally and moderately complex renal cysts

To assess the effectiveness of radiographic surveillance for managing minimally and moderately complex renal cysts. PATIENTS AND METHODS Forty-three patients with 50 minimally or moderately complex renal cysts underwent radiographic surveillance at our institution. Study inclusion criteria were surveillance for >2 years (36 patients, mean follow-up 3.0 years) or surveillance for >6 months with subsequent surgical excision (seven patients, mean follow-up 3.3 years). RESULTS The complexity of the renal cysts was in the form of high attenuation before contrast-enhanced imaging (‘hyperdense’) in 29 patients, thin septations in nine, borderline enhancement in six, thin calcifications in five, and a thick wall in one. The mean initial largest dimension was 2.9 cm and the mean final dimension was 3.0 cm, with the size increased in 29 cysts, decreased in 14 and with no change in seven. The cyst character worsened in seven patients, improved in four and did not change in 39. Eventually seven patients had surgery (laparoscopic partial nephrectomy in five and laparoscopic radical nephrectomy in two), which revealed renal cancer in five. Surgical intervention was prompted by growth alone in two patients, growth and worsening of cyst characteristics in two, new onset of flank pain in one, and appearance of an enhancing nodule in the wall or septa in two. CONCLUSION Radiographic surveillance is an effective method for managing patients with minimally or moderately complex renal cysts. Malignant lesions can be identified and removed while still of low grade and contained, and surgery can be avoided in most patients.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72374/1/j.1464-410X.2008.08171.x.pd

Hyperspectral Probing of Exciton dynamics and Multiplication in PbSe Nanocrystals

Height time hyperspectral near IR probing providing broad-band coverage is employed on PbSe nanocrystals, uncovering spectral evolution following high energy photo-excitation due to hot exciton relaxation and recombination. Separation of single, double and triple exciton state contributions to these spectra is demonstrated, and the mechanisms underlying the course of spectral evolution are investigated. In addition no sign of MEG was detected in this sample up to a photon energy 3.7 times that of the band gap

Ultrafast Carotenoid to Retinal Energy Transfer in Xanthorhodopsin Revealed by the Combination of Transient Absorption and Two-Dimensional Electronic Spectroscopy

By comparing two-dimensional electronic spectroscopy (2DES) and Pump-Probe (PP) measurements on xanthorhodopsin (XR) and reduced-xanthorhodopsin (RXR) complexes, the ultrafast carotenoid-to-retinal energy transfer pathway is revealed, at very early times, by an excess of signal amplitude at the associated cross-peak and by the carotenoid bleaching reduction due to its ground state recovery. The combination of the measured 2DES and PP spectroscopic data with theoretical modelling allows a clear identification of the main experimental signals and a comprehensive interpretation of their origin and dynamics. The remarkable velocity of the energy transfer, despite the non-negligible energy separation between the two chromophores, and the analysis of the underlying transport mechanism, highlight the role played by the ground state carotenoid vibrations in assisting the process

Origins of Photoluminescence Decay Kinetics in CdTe Colloidal Quantum Dots

Recent experimental studies have identified at least two nonradiative components in the fluorescence decay of solutions of CdTe colloidal quantum dots (CQDs). The lifetimes reported by different groups, however, differed by orders of magnitude, raising the question of whether different types of traps were at play in the different samples and experimental conditions and even whether different types of charge carriers were involved in the different trapping processes. Considering that the use of these nanomaterials in biology, optoelectronics, photonics, and photovoltaics is becoming widespread, such a gap in our understanding of carrier dynamics in these systems needs addressing. This is what we do here. Using the state-of-the-art atomistic semiempirical pseudopotential method, we calculate trapping times and nonradiative population decay curves for different CQD sizes considering up to 268 surface traps. We show that the seemingly discrepant experimental results are consistent with the trapping of the hole at unsaturated Te bonds on the dot surface in the presence of different dielectric environments. In particular, the observed increase in the trapping times following air exposure is attributed to the formation of an oxide shell on the dot surface, which increases the dielectric constant of the dot environment. Two types of traps are identified, depending on whether the unsaturated bond is single (type I) or part of a pair of dangling bonds on the same Te atom (type II). The energy landscape relative to transitions to these traps is found to be markedly different in the two cases. As a consequence, the trapping times associated with the different types of traps exhibit a strikingly contrasting sensitivity to variations in the dot environment. Based on these characteristics, we predict the presence of a sub-nanosecond component in all photoluminescence decay curves of CdTe CQDs in the size range considered here if both trap types are present. The absence of such a component is attributed to the suppression of type I traps

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