A Web‐based Open‐source Geoinformation Tool for Regional Water Resources Assessment

Water Resources Management - To reduce the impact of droughts and increase the resilience of regional water systems, various competing demands, such as hydropower, supply, irrigation and river...     

Noncontinent urinary diversion

When the need for urinary diversion arises, whether from carcinoma of the urinary tract, malfunction, or malformation, a decision must be made about the type of diversion to be performed. Currently, the patient and surgeon must decide on continent versus noncontinent versus neobladder, and on the type of intestinal segment to be used.     

Diagnosis of prostatic carcinoma: value of random transrectal sonographically guided biopsies

OBJECTIVE: We studied the efficacy of random, transrectal sonographically guided biopsies in the diagnosis of prostatic carcinoma in a high-risk population. SUBJECTS AND METHODS: During a 2-year period, 570 transrectal sonographically guided prostatic biopsies were done because of clinical findings suggestive of prostatic carcinoma. Biopsies of hypoechoic lesions that were suggestive of carcinoma and segmental random biopsies of normal-appearing lobes of the prostate were performed. Transrectal sonographic findings were correlated with results of pathologic examination of the biopsy specimen and with surgical results, when available. RESULTS: Of the 202 patients found to have carcinoma, the carcinoma was detected with directed biopsy in 145 patients (72%). One hundred twenty (71%) of 169 carcinomas were detected with random biopsy when that procedure was performed. Random biopsies were the only method of diagnosing 57 (28%) of the 202 carcinomas, increasing the yield by 39%. CONCLUSION: Yield of carcinoma on transrectal sonographically guided biopsies increases significantly when segmental random biopsies are performed. Transrectal sonographically guided biopsies should include cores through hypoechoic lesions that are suggestive of carcinoma and bilateral segmental random biopsies.     

Room temperature migration of ion beam injected point defects in crystalline silicon

We have investigated the room temperature diffusion and trapping phenomena of ion beam generated point defects in crystalline Si by monitoring their interaction with dopants, native contaminants such as C and O, and other defects. Spreading resistance measurements show that a small fraction ( 10⁻⁷–10⁻⁶) of the defects generated at the surface by a 40 keV Si implant is injected into the bulk. These defects undergo trap-limited diffusion and produce dopant deactivation and/or partial annihilation of preexisting deep (several micron) defect markers, produced by MeV He implants. It is found that in highly pure, epitaxial Si layers, these effects extend to several microns from the surface, demonstrating a long range migration of point defects at room temperature. A detailed analysis of the experimental evidences allows us to identify the Si self-interstitials injected into the bulk as the major responsible of both dopant deactivation and partial annealing of vacancy-type defects (divacancies, phosphorus-vacancy and oxygen-vacancy) generated by the implants. Finally, a lower limit of 6 × 10⁻¹¹ cm²/s is obtained for the room temperature diffusivity of Si self-interstitials.     

Ion implantation doping of Si for optoelectronic applications

We show that the major problems hampering efficient performances of Si in optoelectronic applications, i.e. the achievement of efficient light emission and fast modulation, can be successfully approached by a proper engineering of its optical properties. In particular, the incorporation of a high Er concentration, if concomitant with codoping with other impurities such as O and F, allows to achieve efficient 1.54 μm light emission at room temperature. This emission arises from an electrically excitable, atomically sharp, intra 4f transition of the Er ions. The formation of impurity-rare earth ion complexes is shown to enhance the effective solubility of Er in Si and optimize its electrical properties thus providing a higher excitation efficiency and a reduction of the temperature quenching of the luminescence yield. Furthermore we show that the proper design of a Si light emitting diode, allowing the incorporation of Er ions within the depletion layer region of a p⁺-n⁺ junction, allows to achieve simultaneously high efficiency and fast modulation of the electroluminescence signal. In fact, under reverse bias, Er ions are pumped with a cross section of 6 × 10⁻¹⁷ cm² and decay with a lifetime of 100 μs, which guarantees an internal quantum efficiency > 10⁻⁴ and an emitted power of 30 μW at room temperature. On the other hand, at the diode turn-off, the onset of fast, non-radiative, Auger-type decay processes of the excited ions allow a very fast turn off of the electroluminescence signal.     

Feasibility analysis of laser action in erbium-doped siliconwaveguides

The authors analyze the feasibility of laser action in erbium-doped silicon devices. The recent experimental results on spontaneous light emission at 1.54 μm from erbium doped silicon diodes and theoretical calculation on Bragg grating technology are used to evaluate the best scenario performances. The effects of processes-induced errors on the threshold conditions are taken into account. They show that laser action in the Er:Si system is feasible     

Elevated alpha-fetoprotein secondary to Hodgkin's lymphoma

We describe the case of a 26-year-old man with an elevated level of alpha-fetoprotein who had no evidence of intragonadal or extragonadal germ cell tumor. The patient was found to have Hodgkin's lymphoma within an anterior mediastinal mass. We review the significance of elevated alpha-fetoprotein levels and discuss the clinical relevance of this unusual presentation of a possible primary Hodgkin's lymphoma.     

Design and fabrication of integrated Si-based optoelectronic devices

We have designed and fabricated novel Si-based optoelectronic devices. To this aim, different Si-based optical sources have been made and their performances at room temperature compared. Er-doped Si p–n junctions, operating at 1.54 μm and exhibiting an efficiency of 0.05% at room temperature, have been integrated with planar Si rib waveguides using either epitaxial Si or silicon on insulators (SOI) wafers. Optical characterization of these waveguides reveals very low transmission losses (below 1 dB/cm). However, Er-doping of the waveguide core, needed for the realization of the light source, results in a large increase of the losses as a consequence of absorption by the free electrons introduced by the rare earths. These losses can be suppressed when the junction is reverse biased and the whole Er profile is embodied in the depletion layer. Since this also allows efficient pumping of Er ions by hot carriers, the performances of the diodes and of the waveguides can be suitably combined. This optimized structure has also been used to design electrically pumped optical amplifiers and lasers, whose performances have been simulated.     

Experimental characterization of proteins immobilized on Si-based materials

We studied the possibility to use techniques that are traditionally employed in microelectronics to detect biological molecules immobilized on and into Si-based materials having, as final goal, the structural characterization of a glucose biosensor. The inorganic immobilization surfaces used were both bulk and porous silicon dioxide and the biological molecule to monitor was the enzyme glucose oxidase, widely used as a sensing element in glucose biosensors. Bulk SiO₂ was used to optimize the immobilization protocol and the step-by-step characterization was mainly carried out by Atomic Force Microscopy measurements. Once optimized, the same protocol was used to anchor the enzyme in a porous Si dioxide matrix. Traditional measurement techniques may fail in biological molecule detection since C, basic element of such biological molecules, is present in Si as a contaminant, or introduced during sample preparation, e.g. for TEM cross section analysis.The enzyme monitoring was carried out by electron diffraction X-ray measurements coupled with scanning electron microscopy and to be sure of the protein presence, it was previously labelled with gold nano particles. We believe that this last measurement technique could be implemented for quantitative direct measurements of the biological molecules concentration in complex matrixes.