Toward Predictive Multiscale Modeling of Vascular Tumor Growth

New directions in medical and biomedical sciences have gradually emerged over recent years that will change the way diseases are diagnosed and treated and are leading to the redirection of medicine toward patient-specific treatments. We refer to these new approaches for studying biomedical systems as predictive medicine, a new version of medical science that involves the use of advanced computer models of biomedical phenomena, high-performance computing, new experimental methods for model data calibration, modern imaging technologies, cutting-edge numerical algorithms for treating large stochastic systems, modern methods for model selection, calibration, validation, verification, and uncertainty quantification, and new approaches for drug design and delivery, all based on predictive models. The methodologies are designed to study events at multiple scales, from genetic data, to sub-cellular signaling mechanisms, to cell interactions, to tissue physics and chemistry, to organs in living human subjects. The present document surveys work on the development and implementation of predictive models of vascular tumor growth, covering aspects of what might be called modeling-and-experimentally based computational oncology. The work described is that of a multi-institutional team, centered at ICES with strong participation by members at M. D. Anderson Cancer Center and University of Texas at San Antonio. This exposition covers topics on signaling models, cell and cell-interaction models, tissue models based on multi-species mixture theories, models of angiogenesis, and beginning work of drug effects. A number of new parallel computer codes for implementing finite-element methods, multi-level Markov Chain Monte Carlo sampling methods, data classification methods, stochastic PDE solvers, statistical inverse algorithms for model calibration and validation, models of events at different spatial and temporal scales is presented. Importantly, new methods for model selection in the presence of uncertainties fundamental to predictive medical science, are described which are based on the notion of Bayesian model plausibilities. Also, as part of this general approach, new codes for determining the sensitivity of model outputs to variations in model parameters are described that provide a basis for assessing the importance of model parameters and controlling and reducing the number of relevant model parameters. Model specific data is to be accessible through careful and model-specific platforms in the Tumor Engineering Laboratory. We describe parallel computer platforms on which large-scale calculations are run as well as specific time-marching algorithms needed to treat stiff systems encountered in some phase-field mixture models. We also cover new non-invasive imaging and data classification methods that provide in vivo data for model validation. The study concludes with a brief discussion of future work and open challenges.     

Organizational Identification: A Context‐Specific Mitigating Resource of Work–Family Conflict

The tension between work and non‐work life remains a critical issue in contemporary careers. This study explores the role of organizational identification (OI) in reducing work–family conflict (WFC) within demanding and high‐stakes jobs in dynamic, uncertain and potentially dangerous contexts (e.g., firefighting). Survey data from 341 firefighters suggest that, congruent with conservation of resources theory and scarcity theory, OI may serve as a resource that mitigates WFC in these contexts. Additionally, the data suggest that the negative relationship between OI and WFC is stronger when trauma is low. For practice, this study provides important implications for employees in similar contexts concerning potential ways to mitigate WFC as well as recommendations concerning exposure to trauma.     

Planning and Planning Education under Conditions of Globalization

The flow of amenity-based migrants to fire-prone areas of the US Rocky Mountain West has brought increasing attention to wildfire hazard mitigation management. This paper attempts to build agent-based models which link natural amenity driven exurban growth to wildfire mitigation regimes to provide a framework for assessing cumulative effects of hazard mitigation policy under alternative policy structures. Three simulations were built to demonstrate how agent-based models (ABM) can be used to examine and compare people's choices of residential location in response to natural amenities and wildfire policies. This paper investigates the ways in which policy effects are incorporated dynamically into the land development decision-making process at an individual level in a case study area. Our results show that individual location choices with respect to wildfire risk are sensitive to wildfire mitigation policies.     

The use of the analytical electron microscope EMMA-4 to study the solute distribution in thin foils: some applications to metals and minerals

Results are reported concerning the application of the analytical electron microscope EMMA-4 to the quantitative analysis of thin foils. A simple procedure by which the observed characteristic X-ray intensities from a thin foil sample can be converted into chemical weight fractions is described. This technique has been applied to study the partitioning of manganese between the carbide and ferrite phases during the isothermal decomposition of a eutectoid steel. The results show that it is possible to analyse the manganese content of the ferrite and carbide phases independently and the partitioning of manganese to the carbide phase has been followed as a function of time at the isothermal transformation temperature. The analysis of a calcium-rich pyroxene which contains calcium-poor precipitate lamellae is described. The results are consistent with the precipitation of a pigeonite, poor in calcium and rich in iron, from an augite host. The third example is the ‘in situ’ analysis of nitride precipitates in a stainless steel. The precipitates are known to contain either titanium or chromium, but it is impossible from morphological or diffraction evidence to differentiate between the two types of nitride. Combined electron microscopy and microprobe analysis is shown to be a rapid and positive means of identifying the precipitates.     

Describing a Beta Probability Distribution Function for Construction Simulation

A typical proposed application for a construction simulation model is to assess the productivity of a future operation. This type of application inherently presents the modeler with a situation where there is only a limited amount of data available for choosing an underlying probability distribution function (PDF). This paper presents a formulation for developing a Beta PDF for use in construction simulation modeling. The hypothesis of this paper is that there is a ratio that relates the 75th percentile to the mode of the activity duration. The research demonstrates that using such ratios, along with the minimum, mode, and maximum activity durations, results in estimates of a beta PDF that accurately describes the underlying duration distribution of construction activities. In the methodology proposed here the minimum and maximum activity durations are predicted using deterministic methods based on the physical characteristics of the job and equipment employed. The beta-shaped parameters a and b are estimated using a procedure for fitting beta distributions to activity times when sample data are not available.     

On a quadratic eigenproblem occurring in regularized total least squares

A computational approach for solving regularized total least squares problems via a sequence of quadratic eigenvalue problems has recently been proposed. Taking advantage of a variational characterization of real eigenvalues of nonlinear eigenproblems the existence of a real right-most eigenvalue for each quadratic eigenvalue problem in the sequence is proven. For large problems the approach is improved considerably utilizing information from the previous quadratic problems and early updates in a nonlinear Arnoldi method.     

Effect of surface hardness of the femur head prosthesis on abrasive wear forces in pairing with polyethylene for artificial hip joints

The problem of wear has become a major issue in total joint replacement. A correlation between biomaterial hardness and abrasive wear mechanisms may be assumed. To investigate the effect of hardness, cobalt-chromium (CoCr) femoral heads coated with hard amorphous-hydrogenated carbon (a-CH) were tested against uncoated heads under conditions of abrasive wear. The heads were paired with polyethylene (UHMWPE) discs in a ball-on-disc machine. The abrasive wear resistance of the heads increased with surface hardness, and qualitatively differing patterns of wear were observed on the UHMWPE surfaces, depending on the abrasive wear of the matching areas of the heads. Accordingly, when evaluating biomaterials for their suitability for use in total joint replacement, hardness should be considered one of the relevant factors among the material properties with an influence on wear.     

Iterative multiuser detection with integrated channel estimation for coded DS-CDMA

A practically interesting approach for iterative channel estimation, multiuser detection, and single-user decoding based on maximum a posteriori symbol-by-symbol estimation for direct sequence/code-division multiple-access (DS-CDMA) is proposed. The receiver relies on the output of a bank of matched filters for each user and each path, and combines interference cancellation with iterated soft-decision feedback to improve channel estimation accuracy and data symbol reliability in course of a few iterations. We show that in this way, near single-user channel phase and amplitude estimation accuracy is achieved for frequency-selective fading channels, even in highly loaded systems, and illustrate that reliable data symbol estimation can be performed.     

The Periscope: supporting a computer enhanced field trip for children

This paper describes an interactive device, the Periscope, designed to be used as an educational tool featured during a children's digitally enhanced field trip in a woodland setting. The Periscope assembly, including a display and RFID equipped tangibles, is controlled using handles that enable it to be raised and rotated. The display is controlled by rotating the Periscope, or alternatively by twisting the handles. A set of tangibles, a collection of Petri dishes fitted with RFID tags, enable the children to carry out experiments with the results being shown on the display. Field trials are also outlined in which the effectiveness of this design is established. In conclusion, we discuss the aesthetic design issues raised by introducing digital technology into everyday environments.     

Coded continuous phase modulation with low-complexity noncoherentreception

Coded continuous phase modulation based on a feedback-free modulator with noncoherent detection is discussed. Low-complexity receiver processing is achieved by using only two or three linear filters for demodulation and applying noncoherent sequence estimation with reduced-state Viterbi decoding and simple branch metric calculation. Overall, the proposed noncoherent receiver provides significant advantages over previously presented approaches