164 research outputs found
Design and performance of an erbium-doped silicon waveguide detector operating at 1.5 ”m
A new concept for an infrared waveguide detector based on silicon is introduced. It is fabricated using silicon-on-insulator material, and consists of an erbium-doped p-n junction located in the core of a silicon ridge waveguide. The detection scheme relies on the optical absorption of 1.5-”m light by Er3+ ions in the waveguide core, followed by electron-hole pair generation by the excited Er and subsequent carrier separation by the electric field of the p-n junction. By performing optical mode calculations and including realistic doping profiles, we show that an external quantum efficiency of 10^-3 can be achieved in a 4-cm-long waveguide detector fabricated using standard silicon processing. It is found that the quantum efficiency of the detector is mainly limited by free carrier absorption in the waveguide core, and may be further enhanced by optimizing the electrical doping profiles. Preliminary photocurrent measurements on an erbium-doped Si waveguide detector at room temperature show a clear erbium related photocurrent at 1.5 ”m
Evidence for increasing rainfall extremes remains elusive at large spatial scales: the case of Italy
The widespread perception of an increase in the severity of extreme rainstorms has not found yet clear confirmation in the scientific literature, often showing vastly different results. Especially for shortâduration extremes, spatial heterogeneities can affect the outcomes of largeâscale trend analyses, providing misleading results dependent on the adopted spatial domain. Based on the availability of a renewed and comprehensive database, the present work assesses the presence of regional trends in the magnitude and frequency of annual rainfall maxima for subâdaily durations in Italy. Versions of the MannâKendall test and a recordâbreaking analysis, that considers the spatial correlation, have been adopted for the scope. Significant trends do not appear at the wholeâcountry scale, but distinct patterns of change emerge in smaller domains having homogeneous geographical characteristics. Results of the study underline the importance of a multiâscale approach to regional trend analysis and the need of more advanced explanations of localized trends
Deep electronic states in ion-implanted Si
In this paper we present an overview of the deep states present after ion-implantation by various species into n-type silicon, measured by Deep Level Transient Spectroscopy (DLTS) and high resolution Laplace DLTS (LDLTS). Both point and small extended defects are found, prior to any anneal, which can therefore be the precursors to more detrimental defects such as end of range loops. We show that the
ion mass is linked to the concentrations of defects that are observed, and the presence of small interstitial clusters directly after ion implantation is established by comparing their behaviour with that of electrically active stacking faults. Finally, future
applications of the LDLTS technique to ion-implanted regions in Si-based devices are outlined.</p
MicroRNA expression profile identifies high grade, non-muscle-invasive bladder tumors at elevated risk to progress to an invasive phenotype
Abstract: The objective of this study was to identify a panel of microRNAs (miRNAs) differentially expressed in high-grade non-muscle invasive (NMI; TaG3âT1G3) urothelial carcinoma that progress to muscle-invasive disease compared to those that remain non-muscle invasive, whether recurrence happens or not. Eighty-nine high-grade NMI urothelial carcinoma lesions were identified and total RNA was extracted from paraffin-embedded tissue. Patients were categorized as either having a non-muscle invasive lesion with no evidence of progression over a 3-year period or as having a similar lesion showing progression to muscle invasion over the same period. In addition, comparison of miRNA expression levels between patients with and without prior intravesical therapy was performed. Total RNA was pooled for microarray analysis in each group (non-progressors and progressors), and qRT-PCR of individual samples validated differential expression between non-progressive and progressive lesions. MiR-32-5p, -224-5p, and -412-3p were associated with cancer-specific survival. Downregulation of miR-203a-3p and miR-205-5p were significantly linked to progression in non-muscle invasive bladder tumors. These miRNAs include those implicated in epithelial mesenchymal transition, previously identified as members of a panel characterizing transition from the non-invasive to invasive phenotype in bladder tumors. Furthermore, we were able to identify specific miRNAs that are linked to postoperative outcome in patients with high grade NMI urothelial carcinoma of the bladder (UCB) that progressed to muscle-invasive (MI) disease
High-resolution satellite products improve hydrological modeling in northern Italy
Satellite-based Earth observations (EO) are an accurate and
reliable data source for atmospheric and environmental science. Their
increasing spatial and temporal resolutions, as well as the seamless
availability over ungauged regions, make them appealing for hydrological
modeling. This work shows recent advances in the use of high-resolution
satellite-based EO data in hydrological modeling. In a set of six
experiments, the distributed hydrological model Continuum is set up for the
Po River basin (Italy) and forced, in turn, by satellite precipitation and
evaporation, while satellite-derived soil moisture (SM) and snow depths are
ingested into the model structure through a data-assimilation scheme.
Further, satellite-based estimates of precipitation, evaporation, and river
discharge are used for hydrological model calibration, and results are
compared with those based on ground observations. Despite the high density
of conventional ground measurements and the strong human influence in the
focus region, all satellite products show strong potential for operational
hydrological applications, with skillful estimates of river discharge
throughout the model domain. Satellite-based evaporation and snow depths
marginally improve (by 2â% and 4â%) the mean KlingâGupta efficiency
(KGE) at 27 river gauges, compared to a baseline simulation
(KGEmean=â0.51) forced by high-quality conventional data. Precipitation
has the largest impact on the model output, though the satellite data on
average shows poorer skills compared to conventional data. Interestingly, a
model calibration heavily relying on satellite data, as opposed to
conventional data, provides a skillful reconstruction of river discharges,
paving the way to fully satellite-driven hydrological applications.</p
Restoration of plakoglobin expression in bladder carcinoma cell lines suppresses cell migration and tumorigenic potential
The reduction or loss of plakoglobin expression in late-stage bladder cancer has been correlated with poor survival where upregulation of this catenin member by histone deacetylase inhibitors has been shown to accompany tumour suppression in an in vivo model. In this study, we directly addressed the question of the role of plakoglobin in bladder tumorigenesis following restoration, or knockdown of expression in bladder carcinoma cell lines. Restoration of plakoglobin expression resulted in a reduction in migration and suppression of tumorigenic potential in vivo. Immunocytochemistry revealed cytoplasmic and membranous localisation of plakoglobin in transfectants with <1% of cells displaying detectable nuclear localisation of plakoglobin. siRNA knockdown experiments targeting plakoglobin, revealed enhanced migration in all cell lines in the presence and absence of E-cadherin expression. In bladder cell lines expressing low levels of plakoglobin and desmoglein-2, elevated levels of desmoglein-2 were detected following restoration of plakoglobin expression in transfected cell lines. Analysis of wnt signalling revealed no activation event associated with plakoglobin expression in the bladder model. These results show that plakoglobin acts as a tumour suppressor gene in bladder carcinoma cells and the silencing of plakoglobin gene expression in late-stage bladder cancer is a primary event in tumour progression
Renal cell carcinoma with inferior vena cava involvement: Prognostic effect of tumor thrombus consistency on cancer specific survival: Tumor Thrombus Consistency and Survival
Renal cell carcinoma forming a venous tumor thrombus (VTT) in the inferior vena cava (IVC) has a poor prognosis. Recent investigations have been focused on prognostic markers of survival. Thrombus consistency (TC) has been proposed to be of significant value but yet there are conflicting data. The aim of this study is to test the effect of IVC VTT consistency on cancer specific survival (CSS) in a multi-institutional cohort
Electron paramagnetic resonance and photoluminescence study of Er-impurity complexes in Si
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