Improved understanding of physical defect mechanisms using fault simulation

Failure mechanisms in highly integrated designs are becoming more subtle, making them difficult to locate and understand. Successful analysis requires the precise location of the anomaly in three dimensions, prior to physical analysis, when strip and inspect techniques do not yield a failure mechanism. This paper presents a technique whereby simulations of hypothesized defects, in combination with I-V curves obtained by electrical microprobing, aid in locating physical defects. Given the exact location, techniques requiring that the physical and chemical sample integrity be maintained, such as TEM and AES, can be employed to give insight into the failure mechanism.     

Crystallization of hydroxybutyrate oligomers. Part 2. Growth and thickening of solution grown crystals observed in situ using synchrotron radiation

Synchrotron X-ray radiation has been used in situ to follow the crystallization of a hydroxybutyrate oligomer containing 32 repeat units from dilute solution in propylene carbonate, and to study chain unfolding during heating in oligomers with 24 and 32 repeat units. A discontinuity in growth rate occurs at 36–37 °C for the 32-mer: crystals grown below this temperature contain folded chains, which transform during heating through a process of partial dissolution and re-crystallization to form extended chain crystals. Crystals grown above the transition temperature contain extended chains that do not rearrange during heating. A similar change happens in the 24-mer between 35 and 40 °C. Thermal expansion in the (110) lattice direction (the fold direction) was in the range 5.3+/−0.3×10⁻⁵ nm °C⁻¹, with an additional discontinuous increase in 0.001 nm accompanying chain unfolding.     

High Voltage MOSFET Gate/Bulk Driver Controller for a Microbattery Switch Matrix in a 0.35 μ m Microwave SOI Technology

Integrated microbatteries are being currently developed to act as a “micropower” source in microsatellites. The current and voltage rating of the microbattery is fixed. Certain highly miniaturized systems require higher voltages and currents. A switching matrix is designed to achieve the same. The switching matrix is designed using High Voltage Metal Oxide Semiconductor (MOS) structures and bulk isolated H gate transistors. This paper presents a design approach to help attain any random grouping pattern between the microbatteries. In this case, the result is an ability to charge microbatteries in parallel and to discharge microbatteries in parallel or pairs of microbatteries in series. This is achieved by providing the appropriate gate/bulk voltages to the matrix. High Voltage MOS structures are developed which can take higher drain-to-source voltages in a 3.3 V process. The designs are built using Microwave Silicon-on-Insulator process. Vinesh Sukumar received the B.E. degree in Electronics and Instrumentation Engineering from Nagarjuna University, Bapatla, India in 2000. He received his M.S. degree in Electrical and Electronics Engineering in 2003 from University of Idaho, Moscow, ID. He is presently pursuing his Doctoral degree in Electrical Engineering at University of Idaho, Moscow, ID. His research interests include Radiation Hard Analog Design and Integrated Power Electronics.     

Coherent Structures in Flat-Bed Abutment Flow: Computational Fluid Dynamics Simulations and Experiments

Numerical computations and laboratory experiments are carried out to investigate the three-dimensional structure of large-scale (coherent) vortices induced by bridge abutments on a flat bed. A finite-volume numerical method is developed for solving the unsteady, three-dimensional Reynolds-averaged Navier–Stokes equations, closed with the k–ω turbulence model, in generalized curvilinear coordinates and applied to study the flow in the vicinity of a typical abutment geometry with a fixed, flat bed. The computed flowfields reveal the presence of multiple, large-scale, unsteady vortices both in the upstream, “quiescent,” region of recirculating fluid and the shear-layer emanating from the edge of the foundation. These computational findings motivated the development of a novel experimental technique for visualizing the footprints of large-scale coherent structures at the free surface. The technique relies on digital photography and employs averaging of instantaneous images over finite-size windows to extract coherent eddies from the chaotic turbulent flow. Application of this technique to several abutment configurations yielded results that support the numerical findings.     

Group norms and attitude–behavior consistency: The role of group salience and mood.

This study tested the social identity–self-categorization theory reconceptualization of the role of norms in attitude–behavior relations. Specifically, the study investigated how the effects of in-group norms on the relationship between people's attitudes and their behavior vary as a function of the salience of group membership and mood. Participants' (N?=?131) attitudes toward students being responsible for picking up litter on campus grounds were examined. As expected, the effects of the attitudinal congruency of norms varied as a function of group salience under neutral mood (i.e., deliberative processing) conditions. In-group norms were more influential for high-salience individuals than for low salience individuals in a neutral mood. These findings indicate that in-group norms influence behavioral decision making for individuals high in group salience only when there is an opportunity to carefully process the normative information. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Self-Organizing Maps of Position Weight Matrices for Motif Discovery in Biological Sequences

The identification of overrepresented motifs in a collection of biological sequences continues to be a relevant and challenging problem in computational biology. Currently popular methods of motif discovery are based on statistical learning theory. In this paper, a machine-learning approach to the motif discovery problem is explored. The approach is based on a Self-Organizing Map (SOM) where the output layer neuron weight vectors are replaced by position weight matrices. This approach can be used to characterise features present in a set of sequences, and thus can be used as an aid in overrepresented motif discovery. The SOM approach to motif discovery is demonstrated using biological sequence datasets, both real and simulated     

I'm a hypocrite, but so is everyone else: Group support and the reduction of cognitive dissonance.

The impact of social support on dissonance arousal was investigated from a social identity view of dissonance theory. This perspective is seen as augmenting current conceptualizations of dissonance theory by predicting when normative information will impact on dissonance arousal and by indicating the availability of identity-related strategies of dissonance reduction. An experiment was conducted to induce feelings of hypocrisy under conditions of behavioral support or nonsupport. Group salience was either high or low, or individual identity was emphasized. As predicted, participants with no support from the salient in-group exhibited the greatest need to reduce dissonance through attitude change and reduced levels of group identification. Results were interpreted in terms of self being central to the arousal and reduction of dissonance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Synthesis, structure, dopamine transporter affinity, and dopamine uptake inhibition of 6-alkyl-3-benzyl-2-[(methoxycarbonyl)methyl]tropane derivatives

A series of 6-alkyl-3 beta-benzyl-2-[(methoxycarbonyl)methyl]tropane analogues were synthesized and evaluated as cocaine binding site ligands at the dopamine transporter (DAT). The in vitro affinity (Ki) for the DAT of the 6-alkyl-3 beta-benzyl-2-[(methoxycarbonyl) methyl]tropane analogues was determined by inhibition of [3H]WIN 35,428 in rat caudate putamen tissue. The inhibition of dopamine uptake (IC50) was also measured for selected compounds which demonstrated moderate affinity for the dopamine transporter. The unsubstituted enantiopure analogues (-)-19a (Ki = 33 nM) and surprisingly (+)-20a (Ki = 60 nM) were found to be almost equipotent with the high-affinity binding components of cocaine and WIN 35,065-2 and exhibited slightly more potent dopamine uptake inhibition than both cocaine and WIN 35,065-2. In general, substitution at the 6-position of racemic 19a and 20a with alkyl groups was found to result in decreased activity relative to increased chain length of the substituent. The 3 beta-benzyl-2 beta-[(methoxycarbonyl)methyl]-6 beta-methyltropane (21b; Ki = 57 nM) was the only 6-alkyl derivative to exhibit moderately potent activity. The 6 beta-isomer 21b was 4-fold more potent than the 6 alpha-isomer 19b (Ki = 211 nM) and was nearly equipotent with (-)-19a and (+)-20a as well as with cocaine and WIN 35,065-2. The results of this study further demonstrate the steric constraints associated with the C(6)-C(7) methylene bridge of the tropane ring system for molecular recognition of cocaine analogues at the cocaine binding site(s) on the DAT.