Structural equation modeling is an important tool in research in the social sciences, and this updated edition keeps pace with the newest methodologies, including providing a SEM-text web page with free access to data and program files for the examples here. Kline (psychology, Concordia U., Montreal) gives beginners and those who want to keep in step fundamental concepts, including basic statistics such as correlation and regression, data preparation and screening, and their applications to SEM techniques and software. He then describes core techniques such as path analysis, measurement models and confirmatory factor analysis, and models with structural and measurement components. He then helps advanced users avoid mistakes in nonrecursive structural models, means structure and latent growth models, and multiple-sample SEM.

Gelman (statistics, Columbia University) and Meng (statistics, Harvard University) collect articles from leading researchers on statistical methods relating to missing data analysis, causal inference, and statistical modeling. Articles provide an overview of several important statistical topics for both research and applications, and describes a range of intermediate and advanced statistical techniques. Applications discussed range from the social and health sciences to the biological and physical sciences. The book is dedicated to Donald Rubin, in recognition of his contributions to statistics, particularly to the topic of statistical analysis with missing data.

Coastal lagoons are notoriously delicate and difficult to manage. In this collection of eight articles and four extensive case studies, contributors examine advanced methods of managing lagoons, including modeling and assessment. Their topics include identifying the ecosystem, analyzing physical and biogeochemical processes, gauging the effects of changing environmental conditions, applying modeling concepts, designing monitoring programs, and making decisions for sustainable use and development. Case studies include examples of wind-driven currents, fast-changing ecosystems under human pressure, transboundary management, and sustainable use and development.

Lambert (industrial ecology, University of Technology, The Netherlands) and Gupta (mechanical and industrial engineering, Northeastern University) introduce disassembly modeling in the context of the entire product life cycle, incorporating material on design for disassembly, concurrent design, and reverse logistics, and discussing theories and methodologies associated with disassembly. Real-world case examples explore three main areas of application: assembly optimization, maintenance and repair, and end-of-life processing. The book will be used by researchers, mechanical and industrial engineers, and processionals involved in concurrent design.

An April 2005 symposium highlighted the latest work in the field in areas including performance modeling and optimization, security and cooperation issues, power control and resource management, infrastructure WLANs, ad hoc and sensor networks, routing and mobility, autonomic and situated communications, and minimum energy broad-casting. Specific topics include energy saving dynamic source routing for ad hoc wireless networks, minimizing delay in loss- tolerant MAC layer multicast, and a simulation tool to evaluate radio resource management algorithms for enhanced UMTS. Other subjects are distributed power allocation and scheduling for parallel channel wireless networks, and a novel call admission control in multiservice wireless LANs. There is no subject index.

Emphasizing applications that require both rapid and precise control of position, speed, and torque, Chiasson (electrical and computer engineering, U. of Tennessee) explains the modeling and control of electric machines, including direct current (DC) machines, but primarily focusing on alternating current (AC) machines consisting of the induction motor, the permanent magnet synchronous motor, and the brushless DC motor. He derives the mathematical models of the machines and then describes how they are used to design control algorithms for high performance. The modeling is based on differential equations and (with the exception of a sinusoidal steady-state analysis of the induction motor) little attention is given to classical equivalent circuits.

Enterprises must continually adapt to changes that occur due to business, political, or technological challenges. These on demand businesses require integration of people, information, and processes in order to conduct business in real time. Meeting the requirements of such a dynamic environment requires leveraging business-to-business (B2B) partnerships and outsourced services by enabling enhanced integration between business processes. For example, supply chain integration of manufacturers and distributors requires deeper examination of sales forecasts, production scheduling, product configuration, and inventory management.

Recently, government requirements for accountability of business practices and information management have transformed security concerns from an isolated piece of the information technology (IT) puzzle into an important and far-reaching business issue that must be addressed. It is no longer sufficient to delegate responsibility to the IT organization alone. Doing so may lead to fragmented business and IT plans along with misallocation and inefficient use of already scarce technology resources.

Femap[R] v9.3 pre and post processing application for engineering finite element analysis allows applying of loads through data surfaces, as well as bolt preload modeling. Supporting dynamic design analysis method for shock spectrum analysis, dynamics analysis, and fluid modeling, it has capability to include 1D, 2D, and 3D data surfaces. It can also expand geometric surfaces to solids, and allows access to API utilities through customer tools toolbar.

PLANO, Texas - UGS Corp., a leading global provider of product lifecycle management (PLM) software and services, today announced the release of Version 9.3 of Femap[R] software, the finite element analysis (FEA) component of the UGS Velocity Series(TM) portfolio.

Femap Version 9.3 is the latest release of UGS' robust pre and post processor for engineering FEA. Femap is known for its tight integration with Nastran[R], in particular UGS' own NX[R] Nastran solver. This latest version of Femap continues a 20-year history of productivity and functionality improvements aimed directly at dedicated engineers and analysts.

"One of Femap's strengths is its depth of integration with the Nastran solvers," said Bill McClure, vice president, UGS Velocity Series. "This new release serves to significantly increase Femap's support of Nastran functionality as well as expand user interface extensions and enhancements to modeling capabilities."

Modeling firm Eqecat Inc. has unveiled its Offshore Energy Model to help insurers manage and quantify their exposure in the offshore energy market. The model is expected to be released in the second quarter of 2007. It covers a range of risk in the Gulf of Mexico for oil and gas platforms, pipelines and other offshore infrastructure, and can account for the removal of debris, business interruption and contingent business interruption.

Nucleosomes form the fundamental building blocks of chromatin. Subtle modifications of the constituent histone tails mediate chromatin stability and regulate gene expression. For this reason, it is important to understand structural dynamics of nucleosomes at atomic levels. We report a novel multiscale model of the fundamental chromatin unit, a nucleosome, using a simplified model for rapid discrete molecular dynamics simulations and an all-atom model for detailed structural investigation. Using a simplified structural model, we perform equilibrium simulations of a single nucleosome at various temperatures. We further reconstruct all-atom nucleosome structures from simulation trajectories. We find that histone tails bind to nucleosomal DNA via strong salt-bridge interactions over a wide range of temperatures, suggesting a mechanism of chromatin structural organization whereby histone tails regulate inter- and intranucleosomal assemblies via binding with nucleosomal DNA. We identify specific regions of the histone core H2A/H2B-H4M3-H3/H4-H2B/H2A, termed "cold sites", which retain a significant fraction of contacts with adjoining residues throughout the simulation, indicating their functional role in nucleosome organization. Cold sites are clustered around H3-H3, H2A-H4 and H4-H2A interhistone interfaces, indicating the necessity of these contacts for nucleosome stability. Essential dynamics analysis of simulation trajectories shows that bending across the H3-H3 is a prominent mode of intranucleosomal dynamics. We postulate that effects of salts on mononucleosomes can be modeled in discrete molecular dynamics by modulating histone-DNA interaction potentials. Local fluctuations in nucleosomal DNA vary significantly along the DNA sequence, suggesting that only a fraction of histone-DNA contacts make strong interactions dominating mononucleosomal dynamics. Our findings suggest that histone tails have a direct functional role in stabilizing higher-order chromatin structure, mediated by salt-bridge interactions with adjacent DNA.

Nucleosomes form the fundamental building blocks of chromatin. Subtle modifications of the constituent histone tails mediate chromatin stability and regulate gene expression. For this reason, it is important to understand structural dynamics of nucleosomes at atomic levels. We report a novel multiscale model of the fundamental chromatin unit, a nucleosome, using a simplified model for rapid discrete molecular dynamics simulations and an all-atom model for detailed structural investigation. Using a simplified structural model, we perform equilibrium simulations of a single nucleosome at various temperatures. We further reconstruct all-atom nucleosome structures from simulation trajectories. We find that histone tails bind to nucleosomal DNA via strong salt-bridge interactions over a wide range of temperatures, suggesting a mechanism of chromatin structural organization whereby histone tails regulate inter- and intranucleosomal assemblies via binding with nucleosomal DNA. We identify specific regions of the histone core H2A/H2B-H4M3-H3/H4-H2B/H2A, termed "cold sites", which retain a significant fraction of contacts with adjoining residues throughout the simulation, indicating their functional role in nucleosome organization. Cold sites are clustered around H3-H3, H2A-H4 and H4-H2A interhistone interfaces, indicating the necessity of these contacts for nucleosome stability. Essential dynamics analysis of simulation trajectories shows that bending across the H3-H3 is a prominent mode of intranucleosomal dynamics. We postulate that effects of salts on mononucleosomes can be modeled in discrete molecular dynamics by modulating histone-DNA interaction potentials. Local fluctuations in nucleosomal DNA vary significantly along the DNA sequence, suggesting that only a fraction of histone-DNA contacts make strong interactions dominating mononucleosomal dynamics. Our findings suggest that histone tails have a direct functional role in stabilizing higher-order chromatin structure, mediated by salt-bridge interactions with adjacent DNA.

Niche modeling; predictions from statistical distributions.

Stockwell, David.

Chapman & Hall/CRC

2007

201 pages

$89.95

Hardcover

Mathematical and computational biology series

QH546

Niche modeling investigates the response of species to their environment and predicts their distribution using tools from mathematics and statistics, data management, and geographical spatial analysis. Stockwell (computer science, U. of California-San Diego) explains the relatively new field to readers who have a basic knowledge of mathematics and programming. Six of the 12 chapters are devoted to sources of errors and how to avoid them. The CiP data shows the title Ecological niche modeling: ecoinformatics in applications to biodiversity.

At present, population pharmacokinetics has taken off with an exponential increase in published papers in the last decade. It is fair to say that population pharmacokinetics has revolutionized how data from clinical studies is analyzed. Population pharmacokinetics methods are used almost exclusively for phase II and III studies and to summarize data across a drug development program. Advances in pharmacokinetic and pharmacodynamic modeling will allow fewer, more focused and informative clinical trials, and lead to significant cost savings. Surprisingly, however, despite these advances, population methods are not routinely taught at the graduate level, and pharmaceutical companies still have difficulty recruiting individuals with population pharmacokinetics experience. A major hindrance to implementing population methods is that it is mathematically and statistically complex, and compared to the number of pharmacokineticists in general there are few modelers who specialize in the methodology. A newcomer can read the literature as a source to learn about population pharmacokinetics. But even this task can be difficult because few papers and books published on pharmacokinetics cover the principles of nonlinear mixed effects models. Some books (mainly written by statisticians) have been written on the relevant topics, but these books are not geared toward reading at the outset of learning the material.

Demands for improved oil recovery prompted the Norwegian oil company, Statoil, to evaluate geologically complex oil and gas-condensate fields offshore Norway with a new approach. Here, major sections of producing reservoirs are heterolithic tidal units of interlayered mud and sand.

Using conventional modeling technology, Statoil geologists could not capture the fine-scale interlayering that would later impact their reservoir property simulations and reserve predictions. A unique multi-scale reservoir modeling tool developed by Geomodeling enabled Statoil to better understand its reservoir assets and choose the right strategies for optimized recovery.

Autodesk Maya v8.5 features Maya Nucleus, which allows creation of elements that interact in 3D with objects such as fluids, cloth, and rigid bodies. Maya nCloth allows direction and control of simulations including cloth, plastic, and metal, while air-pressure model enables use of any geometry from closed, sealed volumes to open volumes such as balloons. Utilizing python scripting, software is available for Mac, Windows, and Linux platforms.

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SAN RAFAEL, Calif., Jan. 15 // -- Autodesk, Inc. (NASDAQ:ADSK) today announced Autodesk Maya 8.5, the latest version of its Maya 3D animation, modeling and rendering software. Maya is widely used for games development, as well as film and television visual effects production. Now shipping, Maya 8.5 gives artists enhanced creative control, enabling faster completion of complex animations and simulations.

"Autodesk is committed to making Maya the foundation for modern production pipelines. Maya 8.5 supports industry-standard Python scripting, offering improved workflows and development productivity," said Marc Petit, Autodesk's Media & Entertainment vice president. "We're excited to offer Maya 8.5 as a Universal application for both Intel-based and PowerPC-based Macintosh computers. As well, the software features innovative new capabilities for character animation; the new Maya Nucleus unified simulation framework enables interactive simulations while keeping artists in full control of the animation."

Recent water sector reforms and increased scarcity and vulnerability of water resources, combined with declining public funding available for large scale infrastructure investment in the sector, have led to a greater awareness by the Government of Vietnam for the need to analyze water resource allocation and use in an integrated fashion, at the basin scale, and from a perspective of economic efficiency. In this study we focus on the development, application, and selected policy analyses using an integrated economic hydrologic river basin model for the Dong Nai River Basin in southern Vietnam. The model framework depicts the sectoral structure and location of water users (agriculture, industry, hydropower, domestic, and the environment) and the institutions for water allocation in the basin. Water benefit functions are developed for the major water uses subject to physical limitations and to constraints of system control and policy. Based on this modeling framework, we will analyze policies that can affect water allocation and use at the basin level, including both basin-specific and general macroeconomic policies.

Natural channel designs often incorporate rigid instream structures to protect channel banks, provide grade control, promote flow deflection, or otherwise improve channel stability. The long term impact of rigid structures on natural stream processes is relatively unknown. The objective of this study was to use long term alluvial channel modeling to evaluate the effect of rigid structures on channel processes and assess current and future stream channel stability. The study was conducted on Oliver Run, a small stream in Pennsylvania relocated due to highway construction. Field data were collected for one year along the 107 m reach to characterize the stream and provide model input, calibration, and verification data. FLUVIAL-12 was used to evaluate the long term impacts of rigid structures on natural channel adjustment, overall channel stability, and changing form and processes. Based on a consideration of model limitations and results, it was concluded that the presence of rigid structures reduced channel width-to-depth ratios, minimized bed elevation changes due to long term aggradation and degradation, limited lateral channel migration, and increased the mean bed material particle size throughout the reach. Results also showed how alluvial channel modeling can be used to improve the stream restoration design effort.

Site-directed spin-labeling and electron paramagnetic resonance are powerful tools for studying structure and conformational dynamics of proteins, especially in membranes. The position of the spin label is used as an indicator of the position of the site to which it is attached. The interpretation of these experiments is based on the assumptions that the spin label does not affect the peptide configuration and that it has a fixed orientation and distance with respect to the protein backbone. Here, the validity of these assumptions is examined through implicit membrane molecular dynamics simulations of the influenza hemagglutinin fusion peptide that has been labeled with methanethiosulfonate spin label. We find that the methanethiosulfonate spin label can occasionally induce peptide orientations that differ from those adopted by the wild-type peptide. Furthermore, the spin-label resides, on average, several Angstroms deeper in the membrane than the corresponding backbone Cα-atom even at sites pointing toward the solvent. The nitroxide spin label exhibits flexibility and adopts various configurations depending on the surrounding residues.

Entire fields within the Earth sciences now exist in which computer modeling has become the primary work of the discipline. Undergraduate geology/Earth science programs have been slow to adapt to this change, and computer science offerings frequently do not meet geology students' needs. To address these problems, a course in Computer Modeling in the Earth Sciences has been developed at Vassar College. The course uses the STELLA (Structural Thinking Experimental Learning Laboratory with Animation) iconographical box modeling software to teach the fundamentals of dynamical systems modeling and then builds on the knowledge students have gained with STELLA to teach introductory programming. Modeling topics include U-Pb concordia/ctiscordia dating techniques, the impact of climate change on a chain of lakes in eastern California, heat flow in permafrost, and flow of ice in glaciers by plastic deformation. The course has been received enthusiastically by students, who reported not only that they enjoyed learning the process of modeling, but also that they had a newfound appreciation for the role of mathematics in geology. Fully documented and debugged STELLA and Fortran models along with reading lists, answer keys, and course notes are available to anyone interested in teaching a course such as this.

Maya 8 offers combination of 64-bit support, multi-threading, and algorithmic optimizations that enable artists to load massive datasets and efficiently interact with them. Key areas of software, including skinning, draw tessellation, and subdivided polygon proxy meshes, have been multi-threaded to scale with number of processors or cores available. Software supports HDR and floating-point images and offers interactive viewing of native and custom mental ray shaders.

Forty-six full papers and 21 short papers from the September 2005 symposium present tools for modeling computer architectures and analyzing protocol performance, storage systems, network traffic, resource management, and wireless networks. The contributors propose a method for understanding how applications use TCP to exchange data, a traffic characterization procedure for multimedia applications in converged networks, an SCM-based adaptive clustering algorithm, and a geographic directed preferential internet topology model. Other topics include visualizing the capacity of a system with behavior uncertainties, dynamic replica placement in content delivery networks, and parallel logic simulation of million-gate VLSI circuits. No subject index is provided.

Working within the overall context of biomechanics, researchers from various disciplines offer information on the different methods for modeling, simulating, and analyzing hard and soft tissue as an aid to developing tools that can provide a meaningful input in medical practice. They discuss how experimental results from a bone chamber are complemented with simulations of a computational model, using real geometry microCT images for reconstruction, three-dimensional geometry reconstruction, making the reconstruction of a femur with osteoporosis and modeling the effects of anti-resorptive drugs, femur behavior with an implant, the influence of different modeling factors in numerical simulations of the situation before and after hip implant surgery, modeling pre-surgery planning in dentistry and urology, evaluating knee ligament reconstruction using numerical modeling, and developing simulation platforms. There is no index. The US office of WIT Press is Computational Mechanics.

MF: All of our readers are dying to know: How'd you earn the name "the Pleasure Machine"?

GR: [Laughs] It actually has nothing to do with what most people would think. I did a commercial for Virgin Airways where I played a stripper, in a real strip club, wearing black boots and a black bikini. In the commercial, there was a famous poet doing a voice-over, and he read the words, "Step aboard the pleasure machine," just as they showed me dancing and spinning around the pole. In Australia, everyone has a nickname, so when people saw the commercial, it just stuck. I love it; I think it's great!

What would a guy need to do to earn the label "Pleasure Machine" in your eyes?
He'd have to have a great body! [Laughs] Especially nice, muscled arms or a nice butt. When I'm in the gym and American football is on, I can't resist stating at the players' tight, shiny pants, because most of the guys have such great buns, legs, and thighs.

You model. You act. You host TV shows. How does a guy get a girl like you?

It's really about chemistry, personality, and making me laugh. If a guy makes me laugh he's halfway there. [Laughs] Combine that with ambition, and you're there.

What was your experiences like on Australia's Celebrity Survivor? Did you anything crazy, like taking your clothes off for chocolate and peanut butter the way Jenna and Heidi did on the American Survivor?