Data Acquisition and Processing Techniques for Voltage Contrast Measurements

The effects of several data acquisition techniques on the accuracy of voltage contrast measurements are studied. In particular, the effect of using a voltage reference region directly connected to an external voltage source in performing the image intensity-to-voltage mapping of a node whose voltage is to be determined is examined. This is found to allow improved voltage measurement. The actual reference curves were obtained by least squares fitting the measured intensity-voltage reference data alternately to a quadratic and a cubic function. In addition, various mapping algorithms are considered including ones based alternately on the use of unprocessed, subtracted and normalized data. Using these techniques, one should expect voltage errors with means of approximately 25 mV and standard deviations of approximately 160 mV even with an unmodified commercial SEM incorporating no additional hardware to increase precision

Advanced Scanning Electron Microscopy Methods and Applications to Integrated Circuit Failure Analysis

Semiconductor device failure analysis using the scanning electron microscope (SEM) has become a standard component of integrated circuit fabrication. Improvements in SEM capabilities and in digital imaging and processing have advanced standard acquisition modes and have promoted new failure analysis methods. The physical basis of various data acquisition modes, both standard and new, and their implementation on a computer controlled SEM image acquisition/processing system are discussed, emphasizing the advantages of each method. Design considerations for an integrated, online failure analysis system are also described. Recent developments in the integration of the information provided by electron beam analysis, conventional integrated circuit (IC) testing, computer-aided design (CAD), and device parameter testing into a single system promise to provide powerful future tools for failure analysis

Cellular Procoagulant Activity Dictates Clot Structure and Stability as a Function of Distance From the Cell Surface

Thrombin concentration modulates fibrin structure and fibrin structure modulates clot stability; however, the impact of localized, cell surface-driven in situ thrombin generation on fibrin structure and stability has not previously been evaluated

Pathogenesis of trimethyltin neuronal toxicity. Ultrastructural and cytochemical observations.

The ultrastructural cytopathologic and cytochemical effects of trimethyltin (TMT) neurotoxicity were delineated in hippocampal and pyriform neurons of acutely intoxicated adult rats. TMT produced neuronal necrosis that preferentially involved hippocampal formation pyriform cortex. The first subcellular alterations were multifocal collection of dense-cored vesicles and tubules and membrane-delimited vacuoles in the cytoplasm of the perikaryon and proximal dendrite. Ultrastructural cytochemical examination revealed that the vesicles and tubules had acid phosphatase activity analagous to Golgi-associated endoplasmic reticulum (GERL). Shortly after the appearance of the GERL-like vesicles and tubules, autophagic vacuoles and polymorphic dense bodies accumulated in the neuronal cytoplasm. Some dense bodies appeared to arise from the dense-cored tubules. Neuronal necrosis was characterized by increased electron density of the cytoplasm and large, electron-dense intranuclear masses. Alterations of mitochondria and other organelles were not observed in the early stages of cell injury. No light- or electron-microscopic alterations were found in liver or kidney. Comparable subcellular alterations were observed in adult and neonatal rats chronically intoxicated with TMT. A series of other trialkyl and tricyclic tins and dimethyltin did not produce similar pathologic findings. The GERL-like accumulations are unique in neuronal cytopathology. These findings suggests that GERL and autophagy play an important role in the pathogenesis of TMT-induced neuronal injury

Endothelin-1 critically influences cardiac function via superoxide-MMP9 cascade

Congestive heart failure develops in human patients and experimental animals when the left ventricle becomes dilated. In the present study, mice were generated having graded genetic levels of endothelin-1 from 20% normal to 350% normal by modifying the 3′ untranslated region of the endothelin-1 gene. The 20% and 65% hypomorphs develop dilated cardiomyopathy, whereas the 350% hypermorph has a hypertrophic heart. Increases in superoxide levels and overexpression of matrix metalloproteinase 9 (MMP9) are involved in the development of the dilated cardiomyopathy in the 20% hypomorph. Our results show that endothelin-1 is critical for maintaining normal cardiac contractile function, for controlling superoxide and Mmp9 levels, and for ensuring that the myocardium has sufficient collagen to prevent overstretching

Optimal control as a graphical model inference problem

We reformulate a class of non-linear stochastic optimal control problems introduced by Todorov (2007) as a Kullback-Leibler (KL) minimization problem. As a result, the optimal control computation reduces to an inference computation and approximate inference methods can be applied to efficiently compute approximate optimal controls. We show how this KL control theory contains the path integral control method as a special case. We provide an example of a block stacking task and a multi-agent cooperative game where we demonstrate how approximate inference can be successfully applied to instances that are too complex for exact computation. We discuss the relation of the KL control approach to other inference approaches to control.Comment: 26 pages, 12 Figures; Machine Learning Journal (2012