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Many organizations that produce a portfolio of products for different customers need to ensure that sensitive or restricted content that may appear in some products must not appear in others. Examples of this need include complying with statutes in different countries of sale, protection of intellectual property developed specifically for one customer, and more. For organizations operating under these requirements and producing their products under a product line engineering paradigm that relies on automation in product derivation, there is a need for a method to ensure that the content restrictions have been met in the derived products. This paper describes an auditing method that meets this need. It was created for use in the Second Generation Product Line Engineering approach that is being applied by Lockheed Martin in their AEGIS ship combat system product line.

Live Training Transformation (LT2) is the product line strategy put in place by the United States Army Program Executive Office for Simulation, Training and Instrumentation (PEO STRI). The purpose of the LT2 product line is to provide a common set of core assets including architectures, software components, standards and processes that form the basis of all Army Live Training systems. As products consuming LT2 core assets evolve to meet the latest requirements of the military live training community, changes to the core product line architecture must also be made. Based on thorough analysis of the LT2 core capabilities and user trends toward web-enabled and mobile computing technologies, a Service Oriented Architecture (SOA) strategy was identified and adopted as the objective architecture for the evolving LT2 product line. Future success of the LT2 product line now depends on the alignment of product line engineering concepts with the business and technical benefits of SOA, and to ensure that systematic reuse continues to provide substantial return-on-investment for the Army. This paper addresses the challenges of adopting SOA into an existing software product line, the unique circumstances of the LT2 SOA environment, and present a set of analysis and design considerations for the product line engineering community.

Left atrial fibrosis is thought to contribute to the manifestation of atrial fibrillation (AF). Late Gadolinium enhancement (LGE) MRI has the potential to image regions of low perfusion, which can be related to fibrosis. We show that a simulation with a patient-specific model including left atrial regional fibrosis derived from LGE-MRI reproduces local activation in the left atrium more precisely than the regular simulation without fibrosis. AF simulations showed a spontaneous termination of the arrhythmia in the absence of fibrosis and a stable rotor center in the presence of fibrosis. The methodology may provide a tool for a deeper understanding of the mechanisms maintaining AF and eventually also for the planning of substrate-guided ablation procedures in the future.

Anatomically realistic computational models provide a powerful platform for investigating mechanisms that underlie atrial rhythm disturbances. In recent years, novel techniques have been developed to construct structurally-detailed, image-based models of 3D atrial anatomy. However, computational models still do not contain full descriptions of the atrial intramural myofiber architecture throughout the entire atria. To address this, a semi-automatic rule-based method was developed for generating multi-layer myofiber orientations in the human atria. The rules for fiber generation are based on the careful anatomic studies of Ho, Anderson and co-workers using dissection, macrophotography and visual tracing of fiber tracts. Separately, a series of high color contrast images were obtained from sheep atria with a novel confocal surface microscopy method. Myofiber orientations in the normal sheep atria were estimated by eigen-analyis of the 3D image structure tensor. These data have been incorporated into an anatomical model that provides the quantitative representation of myofiber architecture in the atrial chambers. In this study, we attempted to compare the two myofiber generation approaches. We observed similar myo-bundle structure in the human and sheep atria, for example in Bachmann's bundle, atrial septum, pectinate muscles, superior vena cava and septo-pulmonary bundle. Our computational simulations also confirmed that the preferential propagation pathways of the activation sequence in both atrial models is qualitatively similar, largely due to the domination of the major muscle bundles.

Model-based segmentation approaches have been proven to produce very accurate segmentation results while simultaneously providing an anatomic labeling for the segmented structures. However, variations of the anatomy, as they are often encountered e.g. on the drainage pattern of the pulmonary veins to the left atrium, cannot be represented by a single model. Automatic model selection extends the model-based segmentation approach to handling significant variational anatomies without user interaction. Using models for the three most common anatomical variations of the left atrium, we propose a method that uses an estimation of the local fit of different models to select the best fitting model automatically. Our approach employs the support vector machine for the automatic model selection. The method was evaluated on 42 very accurate segmentations of MRI scans using three different models. The correct model was chosen in 88.1% of the cases. In a second experiment, reflecting average segmentation results, the model corresponding to the clinical classification was automatically found in 78.0% of the cases.

It is generally true that larger measurement apertures (relative to the source size) produce more accurate reconstructions of sound fields in near-field acoustical holography (NAH) applications. When such apertures are infeasible, numerical extrapolation of the sound field can be implemented to recover data, allowing a successful NAH reconstruction. When the limited aperture is due to a large standoff distance from the source, accurate recovery of data outside the measurement region becomes increasingly critical. In the present paper three data extrapolation methods are implemented on a simulated sound field from two extended, coherent sources. The methods are compared based on their relative accuracy of extrapolated data with distance from the measurement aperture.

Acoustic intensity measurements of the F-22A Raptor are analyzed as part of ongoing efforts to characterize the noise radiation from military jet aircraft. Data were recorded from a rig of microphones and an attached tetrahedral intensity probe at various locations to the sideline and aft of the aircraft. Numerical analysis of the intensity at one-third octave band center frequencies along various measurement planes and at a 23 m radius arc reveals the magnitude and directionality of the vector acoustic intensity. Differences in the trends for low-frequency and high-frequency data are discussed and, via a simple ray tracing back toward the source, interpreted in terms of source location and extent. [Work supported by ONR.]

This chapter is the story of a product line engineering effort under way at General Motors. The product line involves the electronic control systems placed aboard vehicles during manufacturing.

Atrial fibrillation (AF) is the most common cardiac arrhythmia. Patient-specific computational modeling of the atria can provide a better understanding about mechanisms underlying the arrhythmia and will potentially be used for model-based ablation therapy evaluation and planning. Electrical excitation spreads from the left to the right atrium at discrete locations. The location of the muscular bridges cannot be determined from image data. In the present study, left atrial activation sources were manually identified in local activation time maps of 4 AF patients. This information was used to adjust rule-based placed interatrial bridges in anatomical atrial models of the patients. Sinus rhythm simulations showed a better qualitative agreement to the measured left atrial activation patterns after the adjustment of the bridges. For one patient, the simulated body surface potential (BSP) pattern after the adjustment correlated better to measured BSP maps. The results show that the fusion of intracardiac electrical measurements of early left atrial activation can be used to refine patient atria models with information of the myocardial structure which cannot be imaged. In future, such personalized atrial models may be used to support EP interventions.

A detailed computer model which predicts etch rates and spatial uniformity for chemical vapor etching of GaAs with CH3I in a vertical rotating-disk organometallic vapor phase epitaxy (OMVPE) reactor has been developed. Etch rate predictions compare favorably with experiments performed in the vertical reactor at several temperatures ranging from 525 to 590°C and CH3I mole fractions from 0.005 to 0.050 in an H2 carrier gas. Agreement between the data and the model verifies our earlier assertion that gas phase decomposition of CH3I is the rate-limiting step, and that the etchant species are I and to a lesser extent CH3 radicals. Predictions further show that radial etch rate uniformity improves from a 5% variation over 50% of the substrate at low rotation (20–100 rpm) to a 5% variation over 80% of the substrate at 500 rpm. Increasing rotation rate also reduces the etch rate, a result that is in contrast to earlier results for OMVPE growth from TMGa and AsH3. These contrasting results arise because growth is rate limited by gas phase diffusion of TMGa, whereas CH3I vapor etching is rate limited by gas phase decomposition of CH3I.

THE Cascadia subduction zone, a region of converging tectonic plates along the Pacific coast of North America, has a geological history of very large plate-boundary earthquakes1,2, but no such earthquakes have struck this region since Euro-American settlement about 150 years ago. Geophysical estimates of the moment magnitudes (Mw) of the largest such earthquakes range from 8 (ref. 3) to 9 1/2: (ref. 4). Radiocarbon dating of earthquake-killed vegetation can set upper bounds on earthquake size by constraining the length of plate boundary that ruptured in individual earth-quakes. Such dating has shown that the most recent rupture, or series of ruptures, extended at least 55 km along the Washington coast within a period of a few decades about 300 years ago5. Here we report 85 new 14C ages, which suggest that this most recent rupture (or series) extended at least 900 km between southern British Columbia and northern California. By comparing the 14C ages with written records of the past 150 years, we conclude that a single magnitude 9 earthquake, or a series of lesser earthquakes, ruptured most of the length of the Cascadia subduction zone between the late 1600s and early 1800s, and probably in the early 1700s.

The considerable polarization of hyperons produced at high {ital x}{sub {ital F}} has been known for a long time and has been interpreted with various theoretical models in terms of the constituents` spin. Recently, the analyzing power in inclusive {Lambda}{sup 0} hyperon production has also been measured using the 200 GeV/{ital c} Fermilab polarized proton beam. The covered kinematic range is 0.2{le}{ital x}{sub {ital F}}{le}1.0 and 0.1{le}{ital p}{sub {ital T}}{le}1.5 GeV/{ital c}. The data indicate a negative asymmetry at large {ital x}{sub {ital F}} and moderate {ital p}{sub {ital T}}. These results can further test the current ideas on the underlying mechanisms for hyperon polarization. Copyright {ital 1995} {ital The} {ital American} {ital Physical} {ital Society}.

CH3I vapor etching of masked and patterned GaAs substrates has been experimentally investigated. For GaAs samples masked with silicon nitride stripes that are wider than 30 tzm, the etch depth increased compared to unmasked samples, the magnitude of which increased with increasing mask width. Etching of bulk substrates of (lll)Ga and (lll)As GaAs revealed a dependence of etch rate on crystal orientation, with (lll)Ga > (100)GaAs > (lll)As. Increasing etch temperature reduced the orientation dependence of etch rates. Orientation dependence of etch rates was also observed on non-planar GaAs substrates patterned to expose different orientations on wet-etched groove structures. In this case, etch rate differences between the different orientations were amplified when compared to the bulk substrate results. Finally, it was found that the extent of mask undercutting depended on the direction of mask stripes in a fashion consistent with the orientation reactivity results. Mask stripes on (100)GaAs oriented in the [011] direction were severely undercut whereas stripes oriented in the [011] direction were undercut less.

General Motors faces probably the most complex Systems and Software Product Line Engineering (PLE) challenges ever, in terms of product complexity, richness of variation, size of organization, and an unforgiving requirement to support over a dozen simultaneous development streams all geared towards each new model year. To meet this challenge, GM turned to an advanced set of explicitly defined product line engineering solutions, which have been referred to as Second Generation PLE (2GPLE). This includes reliance on features as the lingua franca to express product differences in all phases of the lifecycle, deeply nested hierarchical product lines, industrial strength automation to provide modeling consistency throughout, and more. This paper explains how 2GPLE is being applied at General Motors, and the technical and organizational lessons learned so far.

This paper describes a demonstration of the product line engineering tool and framework Gears from BigLever software. Gears provides a single feature modeling language, a single variation point mechanism, and a single automated product configurator that are used to configure a product portfolio's shared engineering assets appropriately for each product in the portfolio. The result is an automated production line capability that can quickly produce any product in the portfolio from the same, single set of shared assets.

Atrial fibrillation (AF) is the most common cardiac arrhythmia, and the total number of AF patients is constantly increasing. The mechanisms leading to and sustaining AF are not completely understood yet. Heterogeneities in atrial electrophysiology seem to play an important role in this context. Although some heterogeneities have been used in in-silico human atrial modeling studies, they have not been thoroughly investigated. In this study, the original electrophysiological (EP) models of Courtemanche et al., Nygren et al. and Maleckar et al. were adjusted to reproduce action potentials in 13 atrial regions. The parameter sets were validated against experimental action potential duration data and ECG data from patients with AV block. The use of the heterogeneous EP model led to a more synchronized repolarization sequence in a variety of 3D atrial anatomical models. Combination of the heterogeneous EP model with a model of persistent AF-remodeled electrophysiology led to a drastic change in cell electrophysiology. Simulated Ta-waves were significantly shorter under the remodeling. The heterogeneities in cell electrophysiology explain the previously observed Ta-wave effects. The results mark an important step toward the reliable simulation of the atrial repolarization sequence, give a deeper understanding of the mechanism of atrial repolarization and enable further clinical investigations.

Multiscale cardiac modeling has made great advances over the last decade. Highly detailed atrial models were created and used for the investigation of initiation and perpetuation of atrial fibrillation. The next challenge is the use of personalized atrial models in clinical practice. In this study, a framework of simple and robust tools is presented, which enables the generation and validation of patient-specific anatomical and electrophysiological atrial models. Introduction of rule-based atrial fiber orientation produced a realistic excitation sequence and a better correlation to the measured electrocardiograms. Personalization of the global conduction velocity lead to a precise match of the measured P-wave duration. The use of a virtual cohort of nine patient and volunteer models averaged out possible model-specific errors. Intra-atrial excitation conduction was personalized manually from left atrial local activation time maps. Inclusion of LE-MRI data into the simulations revealed possible gaps in ablation lesions. A fast marching level set approach to compute atrial depolarization was extended to incorporate anisotropy and conduction velocity heterogeneities and reproduced the monodomain solution. The presented chain of tools is an important step towards the use of atrial models for the patient-specific AF diagnosis and ablation therapy planing.

Computational atrial models aid the understanding of pathological mechanisms and therapeutic measures in basic research. The use of biophysical models in a clinical environment requires methods to personalize the anatomy and electrophysiology (EP). Strategies for the automation of model generation and for evaluation are needed. In this manuscript, the current efforts of clinical atrial modeling in the euHeart project are summarized within the context of recent publications in this field. Model-based segmentation methods allow for the automatic generation of ready-to-simulate patient-specific anatomical models. EP models can be adapted to patient groups based on a-priori knowledge and to the individual without significant further data acquisition. ECG and intracardiac data build the basis for excitation personalization. Information from late enhancement (LE) MRI can be used to evaluate the success of radio-frequency ablation (RFA) procedures and interactive virtual atria pave the way for RFA planning. Atrial modeling is currently in a transition from the sole use in basic research to future clinical applications. The proposed methods build the framework for model-based diagnosis and therapy evaluation and planning. Complex models allow to understand biophysical mechanisms and enable the development of simplified models for clinical applications.

Model-based segmentation approaches have been proven to produce very accurate segmentation results while simultaneously providing an anatomic labeling for the segmented structures. However, variations of the anatomy, as they are often encountered e.g. on the drainage pattern of the pulmonary veins to the left atrium, cannot be represented by a single model. Automatic model selection extends the model-based segmentation approach to handling significant variational anatomies without user interaction. Using models for the three most common anatomical variations of the left atrium, we propose a method that uses an estimation of the local fit of different models to select the best fitting model automatically. Our approach employs the support vector machine for the automatic model selection. The method was evaluated on 42 very accurate segmentations of MRI scans using three different models. The correct model was chosen in 88.1 % of the cases. In a second experiment, reflecting average segmentation results, the model corresponding to the clinical classification was automatically found in 78.0 % of the cases.

The Responsive Workbench concept was developed as an alternative to the multimedia and virtual reality systems of the past decade. It was recognized that almost nobody wants simulations of their working worlds in a desktop environment. Generally. users want to focus on their tasks rather than on operating the computer. The Responsive Workbench is a virtual working environment that locates virtual objects and control tools on a real "workbench". The objects-computer-generated stereo images-are projected onto the surface of a workbench. This setting corresponds to the actual work situation in an architect's office, in surgery, and so forth. A human guide uses the virtual working environment while several collaborators watch events through stereo shutter glasses. The participants operate within a nonimmersive virtual environment. Depending on the application, the virtual workbench can integrate various input and output modules, such as motion, gesture, and voice recognition systems. This characterizes the general trend away from the classical human-machine interface. Several guides can work together in similar environments either locally or by using broadband communication networks. A responsive environment, consisting of powerful graphics workstations, tracking systems, cameras, projectors, and microphones, replaces the traditional multimedia desktop workstation. >

A serious problem for programs that use persistent data is that information created and maintained by the program becomes invalid if the persistent types used in the program are modified in a new release. Unfortunately, there has been little systematic treatment of the problem; current approaches are manual, ad hoc, and time consuming both for programmers and users. In this article we present a new approach. Focusing on the special case of managing abstract syntax trees in structure-oriented environments, we show how automatic transformers can be generated in terms of an implementor's changes to the grammar of these environments.

Heterologous expression of HIV-1 Gag in a variety of host cells results in its packaging into virus-like particles (VLPs) that are subsequently released into the extracellular milieu. This phenomenon represents a useful tool for probing cellular factors required for viral budding and has contributed to the discovery of roles for ubiquitin ligases and the endosomal sorting complexes required for transport (ESCRTs) in viral budding. These factors are highly conserved throughout eukaryotes and have been studied extensively in the yeast Saccharomyces cerevisiae, a model eukaryote previously utilized as a host for the production of VLPs. We used heterologous expression of HIV Gag in yeast spheroplasts to examine the role of ESCRTs and associated factors (Rsp5, a HECT ubiquitin ligase of the Nedd4 family; Bro1, a homolog of Alix; and Vps4, the AAA-ATPase required for ESCRT function in all contexts/organisms investigated) in the generation of VLPs. Our data reveal: 1) characterized Gag-ESCRT interaction motifs (late domains) are not required for VLP budding, 2) loss of function alleles of the essential HECT ubiquitin ligase Rsp5 do not display defects in VLP formation, and 3) ESCRT function is not required for VLP formation from spheroplasts. These results suggest that the egress of HIV Gag from yeast cells is distinct from the most commonly described mode of exit from mammalian cells, instead mimicking ESCRT-independent VLP formation observed in a subset of mammalian cells. As such, budding of Gag from yeast cells appears to represent ESCRT-independent budding relevant to viral replication in at least some situations. Thus the myriad of genetic and biochemical tools available in the yeast system may be of utility in the study of this aspect of viral budding.

A framework for step-by-step personalization of a computational model of human atria is presented. Beginning with anatomical modeling based on CT or MRI data, next fiber structure is superimposed using a rule-based method. If available, late-enhancement-MRI images can be considered in order to mark fibrotic tissue. A first estimate of individual electrophysiology is gained from BSPM data solving the inverse problem of ECG. A final adjustment of electrophysiology is realized using intracardiac measurements. The framework is applied using several patient data. First clinical application will be computer assisted planning of RF-ablation for treatment of atrial flutter and atrial fibrillation.

Clathrin-mediated endocytosis in mammalian epithelial cells is believed to require the synergistic action of structural coat proteins and mechanochemical enzymes to deform and sever the plasma membrane (PM) into discreet vesicles. It is generally believed that the formation of clathrin-coated pits in epithelial cells occurs randomly along the apical and basolateral plasma membranes. In this study we visualized the endocytic machinery in living hepatocytes using green fluorescent protein (GFP)-tagged dynamin, a large mechanochemical guanosine triphosphate (GTP)ase implicated in the liberation of nascent vesicles from the plasma membrane and a variety of internal membrane compartments. Confocal microscopy of living cells expressing the epithelial isoform of GFP-tagged dynamin [Dyn2-GFP] revealed a distribution along the ventral PM in discrete vesicle-like puncta or in large (2-10 μm) tubuloreticular plaques. Remarkably, these large structures are dynamic as they form and then disappear, while generating large numbers of motile endocytic vesicles with which dynamin associates. Inhibiting dynamin function by microinjection of purified dynamin antibodies increases the number and size of the tubuloreticular plaques. Importantly, these “hot spots” sequester specific trophic receptors and cognate ligands such as transferrin receptor 1 (TfR1), but not TfR2. Conclusion: These findings suggest that hepatocytes sequester or prerecruit both structural and enzymatic components of the clathrin-based endocytic machinery to functional hot spots, from which large numbers of coated pits form and vesicles are generated. This process may mimic the endocytic organization found at the synapse in neuronal cells. (HEPATOLOGY 2011;)

Atrial arrhythmias are frequently treated using catheter ablation during electrophysiological (EP) studies. However, success rates are only moderate and could be improved with the help of personalized simulation models of the atria. In this work, we present a workflow to generate and validate personalized EP simulation models based on routine clinical computed tomography (CT) scans and intracardiac electrograms. From four patient data sets, we created anatomical models from angiographic CT data with an automatic segmentation algorithm. From clinical intracardiac catheter recordings, individual conduction velocities were calculated. In these subject-specific EP models, we simulated different pacing maneuvers and measurements with circular mapping catheters that were applied in the respective patients. This way, normal sinus rhythm and pacing from a coronary sinus catheter were simulated. Wave directions and conduction velocities were quantitatively analyzed in both clinical measurements and simulated data and were compared. On average, the overall difference of wave directions was 15° (8%), and the difference of conduction velocities was 16 cm/s (17%). The method is based on routine clinical measurements and is thus easy to integrate into clinical practice. In the long run, such personalized simulations could therefore assist treatment planning and increase success rates for atrial arrhythmias.

Atrial myofiber orientation is complex and has multiple discrete layers and bundles. A novel robust semi-automatic method to incorporate atrial anisotropy and heterogeneities into patient-specific models is introduced. The user needs to provide 22 distinct seed-points from which a network of auxiliary lines is constructed. These are used to define fiber orientation and myocardial bundles. The method was applied to 14 patient-specific volumetric models derived from CT, MRI and photographic data. Initial electrophysiological simulations show a significant influence of anisotropy and heterogeneity on the excitation pattern and P-wave duration (20.7% shortening). Fiber modeling results show good overall correspondence with anatomical data. Minor modeling errors are observed if more than four pulmonary veins exist in the model. The method is an important step towards creating realistic patient-specific atrial models for clinical applications.

The delineation of anatomical structures in medical images can be achieved in an efficient and robust manner using statistical anatomical organ models, which has been demonstrated for an already considerable set of organs, including the heart. While it is possible to provide models with sufficient shape variability to cope, to a large extent, with inter-patient variability, as long as object topology is conserved, it is a fundamental problem to cope with topological organ variability. We address this by creating a set of model variants and selecting the most appropriate model variant for the patient at hand. We propose a hybrid method combining model-based image analysis with a guided region growing approach for automated anatomical variant selection and apply it to the left atrium in cardiac CT images. Concerning the human heart, the left atrium is the most variable sub-structure with a variable number of pulmonary veins drainng into it. It is of large clinical interest in the context of atrial fibrillation and related interventions.

Electrophysiological simulations of the atria could improve diagnosis and treatment of cardiac arrhythmia, like atrial fibrillation or flutter. For this purpose, a precise segmentation of both atria is needed. However, the atrial epicardium and the electrophysiological structures needed for electrophysiological simulations are barely or not at all detectable in CT-images. Therefore, a model based segmentation of only the atrial endocardium was developed as a landmark generator to facilitate the registration of a finite wall thickness model of the right and left atrial myocardium. It further incorporates atlas information about tissue structures relevant for simulation purposes like Bachmann's bundle, terminal crest, sinus node and the pectinate muscles. The correct model based segmentation of the atrial endocardium was achieved with a mean vertex to surface error of 0.53 mm for the left and 0.18 mm for the right atrium respectively. The atlas based myocardium segmentation yields physiologically correct results well suited for electrophysiological simulations.

Background: The prevalence of atrial fibrillation is increased in patients with end-stage renal disease. Previous studies suggested that extracellular electrolyte alterations caused by hemodialysis (HD) therapy could be proarrhythmic. Methods: Multiscale models were used for a consequent analysis of the effects of extracellular ion concentration changes on atrial electrophysiology. Simulations were based on measured electrolyte concentrations from patients with end-stage renal disease. Results: Simulated conduction velocity and effective refractory period are decreased at the end of an HD session, with potassium having the strongest influence. P-wave is prolonged in patients undergoing HD therapy in the simulation as in measurements. Conclusions: Electrolyte concentration alterations impact atrial electrophysiology from the action potential level to the P-wave and can be proarrhythmic, especially because of induced hypokalemia. Analysis of blood electrolytes enables patient-specific electrophysiology modeling. We are providing a tool to investigate atrial arrhythmias associated with HD therapy, which, in the future, can be used to prevent such complications. © 2011 Elsevier Inc. All rights reserved.

The evolution of thrust structures in the toe-thrust belt of the Niger Delta has been analyzed and reveals a common growth history. Once initiated, structures propagate rapidly along strike with minimal slip. Subsequently, the propagation slows or ceases, and slip accumulation begins to dominate. In the waning stage, deformation retreats toward structural culminations. The pattern of slip evolution across the deep-water thrust belt indicates that neighboring structures are active simultaneously. A structural restoration across the western Niger Delta suggests that a series of detachment advances in the late Miocene initiated when the Akata shale detachment horizon was buried to a depth of around 4 km (2.5 mi) below mud line. These produced a deep-water fold and thrust belt accommodating more than 12 km (7 mi) of shortening. Deformation combined with compaction disequilibrium may have helped produce elevated pore pressures approaching the fracture gradient in the detachment zone. Once the thrust structures began to attain structural height, pore-pressure transfer developed in interbedded sands and silts within the long backlimb of the fault bend folds. This process may have influenced the behavior of the fault zones. A simple model of pore-pressure evolution within the growing structures indicates that pressure transfer can help explain the localization of out-of-sequence thrust growth and might facilitate the focusing of slip toward the central high-relief parts of thrust structures.

Animal glue in combination with other chemicals is often used as a leveling agent in the copper electroplating industry. The control of the glue concentration in the electrolyte is critical to the quality of copper produced. A quantitative galvanostatic technique for glue analysis in copper electrolyte containing lignin sulfonate and Cl− was developed. The kinetics of glue hydrolysis in industrial electrolytes was studied and found to follow first-order reaction kinetics, with sulfuric acid acting as a catalyst. The dependence of the glue hydrolysis rate constant on temperature follows the Arrhenius equation. By adding fresh glue to the electrolyte, the glue activity first rises and then falls. This effect can be explained by the presence of long-chain molecules in the glue which are less active but hydrolyze into the more active medium-sized molecules. A mathematical model of this process shows good agreement with experimental data. The bulk of the electrolyte flow in the INCO commercial electrolytic plating cell bypasses the electrodes, probably across the bottom of the cell. The electrolyte circulation between electrodes is not very intense. A simple equation for the glue concentration calculation in the cell inlet and outlet, depending on the glue addition rate, was derived.

Model-Based Systems Engineering (MBSE) is an emerging engineering discipline whose driving motivation is to provide support throughout the entire system life cycle. MBSE not only addresses the engineering of software systems but also their interplay with physical systems. Quite frequently, successful systems need to be customized to cater for the concrete and specific needs of customers, end-users, and other stakeholders. To effectively meet this demand, it is vital to have in place mechanisms to cope with the variability, the capacity to change, that such customization requires. In this paper we describe our experience in modeling variability using SysML, a leading MBSE language, for developing a product line of wind turbine systems used for the generation of electricity.

In experiments on the interrupted growth of GaAs by organometallic vapor phase epitaxy (OMVPE), we have compared the properties of two types of epilayers: those grown on CH3I-vapor-etched first epilayers and those grown on first epilayers that were either untreated or etched with H2SO4. The OMVPE growth and CH3I etching were performed in two different reactors, and each sample was briefly exposed to air immediately before being placed in the OMVPE reactor for growth of the second epilayer. For CH3I etch temperatures below 500° C, the two types of second epilayers are comparable in surface morphology, as characterized by Nomarski interference microscopy, and in optical quality, as characterized by low-temperature photoluminescence measurements. Electrical characterization by C-V depth profiling shows that electron accumulation at the regrowth interface is increased very little by CH3I etching. Such etching prior to regrowth eliminates most of the electron accumulation resulting from H2SO4 etching of the first epilayer.

The 700mm2 65nm Itanium® processor codenamed Tukwila [1] integrates four cores and a system interface with six QuickPath® interconnect channels and four memory interconnect channels. The large die, shown in Fig. 3.4.6, and high level of integration coupled with process variability present clock-system design challenges in the areas of power consumption and variability compensation that we discuss in this paper. Figure 3.4.1 shows the clock system, which is a cascaded-PLL architecture with an initial filter PLL that receives a 133MHz reference clock. This maiden PLL filters reference-clock jitter and outputs a 133MHz clock to 13 downstream PLLs. Each downstream PLL has a duty-cycle corrector that monitors and corrects the end-of-route duty cycle.

The human atria contain fine structures, which can hardly be distinguished with common medical imaging techniques. However, some of these structures play an important role in the electrophysiologic depolarisation sequence of the atria. We present a semi-automatic algorithm to segment the sinus node, Bachmann’s Bundle and the Terminal Crest in given anatomical shape models of the atria. The algorithm bases on anatomical knowledge of the atria and only requires the user to provide few distinct landmarks in the atria as input. Incorporation of these structures into patient individual atrial geometries augments the electrophysiological correctness of the models.

Atrial fibrillation (AF) is the most common cardiac arrhythmia in the western world. Genetic variants in the cardiac I Kr channel have been identified to influence ventricular repolarization. The aim of this work is to investigate the effect of the mutation N588K on atrial repolarization and the predisposition to AF. Experimental data of N588K mutated hERG channel were incorporated in an atrial ionic model using parameter fitting. The effects of the mutation were analyzed in cell and tissue. N588K showed a gain of function effect, causing a rapid repolarization and a shortening of the action potential duration. Computer simulations of a schematic right atrial geometry were used to investigate the excitation conduction properties. The effective refractory period of mutant cells were reduced from 317 to 233 ms at 1 Hz . The conduction velocity is not significantly influenced by the mutation. Nevertheless, the wavelength of mutant cells is for all frequencies smaller, indicating that the mutation N588K predisposes the initiation and perpetuation of AF.

The participation of cardiac myosin hinge in contractility was investigated by in vitro motility and ATPase assays and by measurements of sarcomere shortening. The effect on contractile activity was analyzed using an antibody directed against a 20-amino acid peptide within the hinge region of myosin. This antibody bound specifically at the hinge at a distance of 55 nm from the S1/S2 junction, was specific to human, dog, and rat cardiac myosins, did not crossreact with gizzard or skeletal myosin, and had no effect on ATPase activity of purified S1 and myofibrils. However, it completely suppressed the movement of actin filaments in in vitro motility assays and reduced active shortening of sarcomeres of skinned cardiac myocytes by half. Suppression of motion by the anti-hinge antibody may reflect a mechanical constraint imposed by the antibody upon the mobility of the S2 region of myosin. The results suggest that the steps in the mechanochemical energy transduction can be separately influenced through S2.

The validity of using carbon isotopes in biological apatite from bone for dietary studies has been questioned because of diagenetic alterations and supposed exchange of carbon from the burial environment. Laboratory and natural experiments have been devised to test the integrity of carbon isotope ratios in biological apatite with respect to isotopic exchange of carbon with natural waters. The laboratory experiment subjected a sample of bone to a synthetic groundwater whose carbon isotopic composition had been adjusted to +9750‰. Analyses indicate that simple carbonates exchanged rapidly with the groundwater, but that the actual biological apatite exchanged very little, if any, of its carbon, even with 2 years exposure. The natural experiment involved analysis of mammoth and mastodon teeth that had been submerged in sea water for 11,000 years. With proper cleaning, the original dietary signals were well-preserved despite the long exposure to oceanic dissolved carbonate of much different isotopic composition. These experiments suggest that properly cleaned biological apatite is an appropriate analytical phase for dietary studies on bone or teeth as old as 10,000 years.

The genesis of HomeAway, Inc. was startup by accretion - eight companies in the web-based vacation home rental market were acquired and merged. The technical solution during the merger and acquisition phase was to assimilate the software functionality of each of the eight companies into a one-size-fits-all application that could be configured with runtime settings to support the look-and-feel of the original eight. When rapid growth and an aggressive business plan pushed the one-size-fits-all approach beyond its limits, HomeAway decisively applied the 3-tiered software product line (SPL) methodology and the gears unified SPL Framework to transition to a software product line practice. This case study explores how HomeAway leveraged the 3-tiered methodology and gears to make their transition, accelerate software development, reduce defect density, lower development overhead, and extend the scalability of its portfolio to better achieve its aggressive business goals - all within 60 days.

Stereoscopic head-mounted displays (HMD's) provide an effective capability to create dynamic virtual environments. For a user of such environments, virtual objects would be displayed ideally at the appropriate distances, and natural concordant accommodation and convergence would be provided. Under such image display conditions, the user perceives these objects as if they were objects in a real environment. Current HMD technology requires convergent eye movements. However, it is currently limited by fixed visual accommodation, which is inconsistent with real-world vision. A prototype multiplanar volumetric projection display based on a stack of laminated planes was built for medical visualization as discussed in a paper presented at a 1999 Advanced Research Projects Agency workshop (Sullivan, Advanced Research Projects Agency, Arlington, Va., 1999). We show how such technology can be engineered to create a set of virtual planes appropriately configured in visual space to suppress conflicts of convergence and accommodation in HMD's. Although some scanning mechanism could be employed to create a set of desirable planes from a two-dimensional conventional display, multiplanar technology accomplishes such function with no moving parts. Based on optical principles and human vision, we present a comprehensive investigation of the engineering specification of multiplanar technology for integration in HMD's. Using selected human visual acuity and stereoacuity criteria, we show that the display requires at most 27 equally spaced planes, which is within the capability of current research and development display devices, located within a maximal 26-mm-wide stack. We further show that the necessary in-plane resolution is of the order of 5 microm.

The 700mm2 65nm Itaniumreg processor doubles the number of cores over its predecessor, from 2 to 4. It also adds a system interface that is roughly as large as two cores, including six QuickPath interconnects and four FBDIMM channels. This 3x increase in logic circuits per socket presents two major circuit challenges that are addressed in this paper.