A Technical Note on Quantum Dots for Multi-Color Fluorescence in situ Hybridization

Quantum dots (Qdots) are semiconductor nanocrystals, which are photo-stable, show bright fluorescence with narrow, symmetric emission spectra and are available in multiple resolvable colors. We established a FISH protocol for the simultaneous visualization of up to 6 different DNA probes differentially labeled with Qdots and with conventional organic fluorochromes. Using a Leica SP5 laser scanning confocal microscope for image capture, we tested various combinations of hapten-labeled probes detected with streptavidin-Qdot525, sheep anti-digoxigenin-Qdot605, rat anti-dinitrophenyl-Qdot655 and goat anti-mouse-Qdot655, respectively, together with FITC-dUTP-, Cy3-dUTP- and Texas Red-dUTP-labeled probes. We further demonstrate that Qdots are suitable for imaging of FISH probes using 4Pi microscopy, which promises to push the resolution limits of light microscopy to 100 nanometers or less when applying a deconvolution algorithm, but requires the use of highly photo-stable fluors. Copyright (C) 2009 S. Karger AG, Base

A Simpler (and Better) SQL Approach to Relational Division

A common type of database query requires one to find all tuples of some table that are related to each and every one of the tuples of a second group. In general those queries can be solved using the relational algebra division operator. Relational division is very common and appears frequently in many queries. However, we have found that the phrasing of this operator in SQL seems to present an overwhelming challenge to novice and experienced database programmers. Furthermore, students seem to have the most problems with the SQL version commonly recommended in the database literature. We present an alternative solution that is not only more intuitive and easier to deliver in the classroom but also exhibits a better computational performance

Role of hydrogen in volatile behaviour of defects in SiO2-based electronic devices

Charge capture and emission by point defects in gate oxides of metal–oxide–semiconductor field-effect transistors (MOSFETs) strongly affect reliability and performance of electronic devices. Recent advances in experimental techniques used for probing defect properties have led to new insights into their characteristics. In particular, these experimental data show a repeated dis- and reappearance (the so-called volatility) of the defect-related signals. We use multiscale modelling to explain the charge capture and emission as well as defect volatility in amorphous SiO2 gate dielectrics. We first briefly discuss the recent experimental results and use a multiphonon charge capture model to describe the charge-trapping behaviour of defects in silicon-based MOSFETs. We then link this model to ab initio calculations that investigate the three most promising defect candidates. Statistical distributions of defect characteristics obtained from ab initio calculations in amorphous SiO2 are compared with the experimentally measured statistical properties of charge traps. This allows us to suggest an atomistic mechanism to explain the experimentally observed volatile behaviour of defects. We conclude that the hydroxyl-E′ centre is a promising candidate to explain all the observed features, including defect volatility

Acquired heart block: A possible complication of patent ductus arteriosus in a preterm infant

A large patent ductus arteriosus (PDA) is a frequently encountered clinical problem in extremely low birth weight (ELBW) infants. It leads to an increased pulmonary blood flow and in a decreased or reversed diastolic flow in the systemic circulation, resulting in complications. Here we report a possible complication of PDA not previously published. On day 8 of life, a male ELBW infant (birth weight 650 g) born at a gestational age of 23 weeks and 3 days developed an atrioventricular block (AV block). The heart rate dropped from 168/min to 90/min, and the ECG showed a Wenckebach second-degree AV block and intraventricular conduction disturbances. Echocardiography demonstrated a PDA with a large left-to-right shunt and large left atrium and left ventricle with high contractility. Within several minutes after surgical closure of the PDA, the heart rate increased, and after 30 min the AV block had improved to a 1: 1 conduction ratio. Echocardiography after 2 h revealed a significant decrease of the left ventricular and atrial dimensions. Within 12 h, the AV block completely reversed together with the intraventricular conduction disturbances. We suggest that PDA with a large left-to-right shunt and left ventricular volume overload may lead to an AV block in an ELBW infant. Surgical closure of the PDA may be indicated. Copyright (C) 2007 S. Karger AG, Basel

A numerical study of partial-SOI LDMOSFETs

Abstract The high-voltage and self-heating behavior of partial-SOI (silicon-on-insulator) LDMOSFETs were studied numerically. Different locations of the silicon window were considered to investigate the electrical and thermal effects. It is found that the potential distribution of the partial-SOI LDMOSFET with the silicon window under the drain is similar to that of standard junction isolation devices. With the silicon window under the source the potential distribution is similar to that of the conventional SOI LDMOSFET. Using the two-dimensional numerical simulator MINIMOS-NT, we confirm that the breakdown voltage of partial-SOI LDMOSFETs with a silicon window under the source is higher than that of partial-SOI LDMOSFET with a silicon window under the drain

Advanced Modeling of Charge Trapping: RTN, 1/f noise, SILC, and BTI (Invited Paper)

Abstract-In the course of years, several models have been put forward to explain noise phenomena, bias temperature instability (BTI), and gate leakage currents amongst other reliability issues. Mostly, these models have been developed independently and without considering that they may be caused by the same physical phenomenon. However, new experimental techniques have emerged, which are capable of studying these reliability issue on a microscopic level. One of them is the time-dependent defect spectroscopy (TDDS). Its intensive use has led to several interesting findings, including the fact that the recoverable component of BTI is due to reaction-limited processes. As a consequence, a quite detailed picture of the processes governing BTI has emerged. Interestingly, this picture has also been found to match the observations made for other reliability issues, such as random telegraph noise, 1/f noise, as well as gate leakage currents. Furthermore, the findings based on TDDS have lead to the development of capture/emission time (CET) maps, which can be used to understand the dynamic response of the defects given their widely distributed parameters

Advanced Modeling of Charge Trapping: RTN, 1/f noise, SILC, and BTI (Invited Paper)

Abstract-In the course of years, several models have been put forward to explain noise phenomena, bias temperature instability (BTI), and gate leakage currents amongst other reliability issues. Mostly, these models have been developed independently and without considering that they may be caused by the same physical phenomenon. However, new experimental techniques have emerged, which are capable of studying these reliability issue on a microscopic level. One of them is the time-dependent defect spectroscopy (TDDS). Its intensive use has led to several interesting findings, including the fact that the recoverable component of BTI is due to reaction-limited processes. As a consequence, a quite detailed picture of the processes governing BTI has emerged. Interestingly, this picture has also been found to match the observations made for other reliability issues, such as random telegraph noise, 1/f noise, as well as gate leakage currents. Furthermore, the findings based on TDDS have lead to the development of capture/emission time (CET) maps, which can be used to understand the dynamic response of the defects given their widely distributed parameters

Expanding TCAD Simulations from Grid to Cloud

Abstract-In this work, the distribution, execution and performance of TCAD simulations on grid and cloud systems are investigated. A module for distributed computing which can uniformly interface both grid and cloud computing systems has been implemented within GTS Framework. Automated allocation of resources for user jobs on a combined platform has been achieved. Traditional grid-computing systems are compared with cloud-based systems. Strategies for cost-effective allocation of cloud-resources are presented. The performance of a typical TCAD application run on a grid, in the cloud, and a hybrid system combining both are assessed