Kinetic Monte Carlo simulations of Ge-Sb-Te thin film crystallization

Simulation of atomic redistribution in Ge-Sb-Te (GST)-based memory cells during SET/RESET cycling is needed in order to understand GST memory cell failure and to design improved non-volatile memories. However, this type of atomic scale simulations is extremely challenging. In this work, we propose to use a simplified GST system in order to catch the basics of atomic redistribution in Ge-rich GST (GrGST) films using atomistic kinetic Monte Carlo simulations. Comparison between experiments and simulations shows good agreements regarding the influence of Ge excess on GrGST crystallization, as well as concerning the GST growth kinetic in GrGST films, suggesting the crystallized GST ternary compound to be off-stoichiometric. According to the simulation of atomic redistribution in GrGST films during SET/RESET cycling, the film microstructure stabilized during cycling is significantly dependent of the GST ternary phase stoichiometry. The use of amorphous layers exhibiting the GST ternary phase stoichiometry placed at the bottom or at the top of the GrGST layer is shown to be a way of controlling the microstructure evolution of the film during cycling. The significant evolution of the local composition in the amorphous solution during cycling suggests a non-negligible variation of the crystallization temperature with operation time.

Scoring Cercospora Leaf Spot on Sugar Beet: Comparison of UGV and UAV Phenotyping Systems

Selection of sugar beet (Beta vulgaris L.) cultivars that are resistant to Cercospora Leaf Spot (CLS) disease is critical to increase yield. Such selection requires an automatic, fast, and objective method to assess CLS severity on thousands of cultivars in the field. For this purpose, we compare the use of submillimeter scale RGB imagery acquired from an Unmanned Ground Vehicle (UGV) under active illumination and centimeter scale multispectral imagery acquired from an Unmanned Aerial Vehicle (UAV) under passive illumination. Several variables are extracted from the images (spot density and spot size for UGV, green fraction for UGV and UAV) and related to visual scores assessed by an expert. Results show that spot density and green fraction are critical variables to assess low and high CLS severities, respectively, which emphasizes the importance of having submillimeter images to early detect CLS in field conditions. Genotype sensitivity to CLS can then be accurately retrieved based on time integrals of UGV- and UAV-derived scores. While UGV shows the best estimation performance, UAV can show accurate estimates of cultivar sensitivity if the data are properly acquired. Advantages and limitations of UGV, UAV, and visual scoring methods are finally discussed in the perspective of high-throughput phenotyping.

Inelastic electron scattering observation using energy filtered transmission electron microscopy for silicon -- germanium nanostructures imaging

This paper presents a new technique using energy filtered TEM (EFTEM) for inelastic electron scattering contrast imaging of Germanium distribution in Si-SiGe nanostructures. Comparing electron energy loss spectra (EELS) obtained in both SiGe and Si single crystals, we found a spectrum area strongly sensitive to the presence of Ge in the range [50-100 eV]. In this energy loss window, EELS spectrum shows a smooth steeply shaped background strongly depending on Ge concentration. Germanium mapping inside SiGe can thus be performed through imaging of the EELS background slope variation, obtained by processing the ratio of two energy filtered TEM images, respectively, acquired at 90 and 60 eV. This technique gives contrasted images strongly similar to those obtained using STEM Z-contrast, but presenting some advantages: elastic interaction (diffraction) is eliminated, and contrast is insensitive to polycrystalline grains orientation or specimen thickness. Moreover, since the extracted signal is a spectral signature (inelastic energy loss) we demonstrate that it can be used for observation and quantification of Ge concentration depth profile of SiGe buried layers.

Urodynamic assessment of stress incontinence and its therapeutic implications

Urethral fibrosis and sphincter incompetence commonly are associated in the genesis of stress incontinence. Other factors are often associated, such as bladder hyperactivity and increased demand on the sphincter mechanism created by contracted or large atonic bladder or polyuria. The frequent association of several factors and the limited information given by the classical methods suggest a need for the routine use of objective urodynamic studies in the assessment of stress incontinence. A more conservative, better oriented, therapeutic approach may result from this concept.

Role of uroflowmetry in the assessment of lower urinary tract obstruction in adult males

A group of 173 prostatic patients were submitted to a prospective study to determine the respective value of symptoms, uroflowmetry, endoscopic and radiological findings in the assessment of the degree of urinary obstruction. Uroflowmetry proved to bring objective evidence of the degree of obstruction with a reasonable degree of accuracy. Maximum urinary flow appears to be more accurate than other flow parameters in the determination of lower urinary tract obstruction.

Evolution of urinary flow rate with prostatectomy

Urinary flow rate was studied before and after transurethral prostatectomy in 53 patients. An average of 43.8 percent improvement in maximum flow rate after transurethral prostatectomy was observed in this series. Improvement of maximum flow rate occurred in 71 per cent of patients. Half of the cases in which flow rate did not improve were chronic prostatitis. Uroflowmetry cannot be utilized as a quality index of a transurethral prostatic resection as long as the degree of detrusor deterioration is not assessed. There is a relationship between the degree of preoperative symptoms and the degree of postoperative urinary flow improvement. The degree of preoperative symptoms and urinary flow deviation are not related which suggests that uroflowmetry adds to the assessment of symptoms in the determination of the degree of obstruction. Patients presenting difficulty of urination have a greater chance to demonstrate urinary flow improvement after surgery than patients complaining of urinary frequency.