Crashworthiness and composite materials: development of an experimental test method for the energy absorption determination and implementation of the relative numerical model

In this PhD thesis the crashworthiness topic is studied with the perspective of the development of a small-scale experimental test able to characterize a material in terms of energy absorption. The material properties obtained are then used to validate a nu- merical model of the experimental test itself. Consequently, the numerical model, calibrated on the specific ma- terial, can be extended to more complex structures and used to simulate their energy absorption behavior. The experimental activity started at University of Washington in Seattle, WA (USA) and continued at Second Faculty of Engi- neering, University of Bologna, Forl`ı (Italy), where the numerical model for the simulation of the experimental test was implemented and optimized.

Validation of statistical shape model based reconstruction of the proximal femur - A morphology study

Seventeen bones (sixteen cadaveric bones and one plastic bone) were used to validate a method for reconstructing a surface model of the proximal femur from 2D X-ray radiographs and a statistical shape model that was constructed from thirty training surface models. Unlike previously introduced validation studies, where surface-based distance errors were used to evaluate the reconstruction accuracy, here we propose to use errors measured based on clinically relevant morphometric parameters. For this purpose, a program was developed to robustly extract those morphometric parameters from the thirty training surface models (training population), from the seventeen surface models reconstructed from X-ray radiographs, and from the seventeen ground truth surface models obtained either by a CT-scan reconstruction method or by a laser-scan reconstruction method. A statistical analysis was then performed to classify the seventeen test bones into two categories: normal cases and outliers. This classification step depends on the measured parameters of the particular test bone. In case all parameters of a test bone were covered by the training population's parameter ranges, this bone is classified as normal bone, otherwise as outlier bone. Our experimental results showed that statistically there was no significant difference between the morphometric parameters extracted from the reconstructed surface models of the normal cases and those extracted from the reconstructed surface models of the outliers. Therefore, our statistical shape model based reconstruction technique can be used to reconstruct not only the surface model of a normal bone but also that of an outlier bone.

Statistical model-based segmentation of the proximal femur in digital antero-posterior (AP) pelvic radiographs.

PURPOSE    Segmentation of the proximal femur in digital antero-posterior (AP) pelvic radiographs is required to create a three-dimensional model of the hip joint for use in planning and treatment. However, manually extracting the femoral contour is tedious and prone to subjective bias, while automatic segmentation must accommodate poor image quality, anatomical structure overlap, and femur deformity. A new method was developed for femur segmentation in AP pelvic radiographs. METHODS    Using manual annotations on 100 AP pelvic radiographs, a statistical shape model (SSM) and a statistical appearance model (SAM) of the femur contour were constructed. The SSM and SAM were used to segment new AP pelvic radiographs with a three-stage approach. At initialization, the mean SSM model is coarsely registered to the femur in the AP radiograph through a scaled rigid registration. Mahalanobis distance defined on the SAM is employed as the search criteria for each annotated suggested landmark location. Dynamic programming was used to eliminate ambiguities. After all landmarks are assigned, a regularized non-rigid registration method deforms the current mean shape of SSM to produce a new segmentation of proximal femur. The second and third stages are iteratively executed to convergence. RESULTS    A set of 100 clinical AP pelvic radiographs (not used for training) were evaluated. The mean segmentation error was [Formula: see text], requiring [Formula: see text] s per case when implemented with Matlab. The influence of the initialization on segmentation results was tested by six clinicians, demonstrating no significance difference. CONCLUSIONS    A fast, robust and accurate method for femur segmentation in digital AP pelvic radiographs was developed by combining SSM and SAM with dynamic programming. This method can be extended to segmentation of other bony structures such as the pelvis.

A Model Study of the Circulation in the Pearl River Estuary (PRE) and Its Adjacent Coastal Waters: 1. Simulations and Comparison with Observations

The Princeton Ocean Model is used to study the circulation features in the Pearl River Estuary and their responses to tide, river discharge, wind, and heat flux in the winter dry and summer wet seasons. The model has an orthogonal curvilinear grid in the horizontal plane with variable spacing from 0.5 km in the estuary to 1 km on the shelf and 15 sigma levels in the vertical direction. The initial conditions and the subtidal open boundary forcing are obtained from an associated larger-scale model of the northern South China Sea. Buoyancy forcing uses the climatological monthly heat fluxes and river discharges, and both the climatological monthly wind and the realistic wind are used in the sensitivity experiments. The tidal forcing is represented by sinusoidal functions with the observed amplitudes and phases. In this paper, the simulated tide is first examined. The simulated seasonal distributions of the salinity, as well as the temporal variations of the salinity and velocity over a tidal cycle are described and then compared with the in situ survey data from July 1999 and January 2000. The model successfully reproduces the main hydrodynamic processes, such as the stratification, mixing, frontal dynamics, summer upwelling, two-layer gravitational circulation, etc., and the distributions of hydrodynamic parameters in the Pearl River Estuary and coastal waters for both the winter and the summer season.

Fluid-structure interaction of an elastic pipe immersed inside a coaxial rigid pipe: a model for the Tullio phenomenon

An axisymmetric, elastic pipe is filled with an incompressible fluid and is immersed in a second, coaxial rigid pipe which contains the same fluid. A pressure pulse in the outer fluid annulus deforms the elastic pipe which invokes a fluid motion in the fluid core. It is the aim of this study to investigate streaming phenomena in the core which may originate from such a fluid-structure interaction. This work presents a numerical solver for such a configuration. It was developed in the OpenFOAM software environment and is based on the Arbitrary Lagrangian Eulerian (ALE) approach for moving meshes. The solver features a monolithic integration of the one-dimensional, coupled system between the elastic structure and the outer fluid annulus into a dynamic boundary condition for the moving surface of the fluid core. Results indicate that our configuration may serve as a mechanical model of the Tullio Phenomenon (sound-induced vertigo).

A Model of Rights

In this paper, we develop a simple model of the rights a government provides its citizenry. Rights are treated as public goods and taken as primitives in agents utility functions; each agent has preferences over the entire policy vector. We model the interaction among citi-zens and the government as a game in which an exogenous lobbying set makes contributions to the government to in uence policy formu-lation in the matter of rights. When examining contribution schedules comprising truthful Nash strategies, we find that members of the lob-bying set obtain rights closer to their most-preferred bundle, while the rights of non-lobbyers further diverge from their most-preferred bun-dle. Further, if the lobbying set comprises the entire population, the government s allocation of rights does not differ from the allocation achieved in the absence of contributions.

The Flowchart Model of Cluster Policy: The Automobile Industry Cluster in China

This paper proposes a general model of the flowchart approach to industrial cluster policy and applies this model to Guangzhou's automobile industry cluster. The flowchart approach to industrial cluster policy is an action plan for prioritizing policy measures in a time-ordered series. We reached the following two conclusions. First,we clarified the effects of Honda, Nissan, and Toyota on agglomeration in Guangzhou's automobile industry cluster. Second, we established that local governments play a crucial role in successful industrial cluster policy, and that the mayor of the local government should be offered incentives in order to target industrial clustering and implement cluster policy.

Approximate Analytical Model for the Squeeze-Film Lubrication of the Human Ankle Joint with Synovial Fluid Filtrated by Articular Cartilage

The aim of this article is to propose an analytical approximate squeeze-film lubrication model of the human ankle joint for a quick assessment of the synovial pressure field and the load carrying due to the squeeze motion. The model starts from the theory of boosted lubrication for the human articular joints lubrication (Walker et al., Rheum Dis 27:512–520, 1968; Maroudas, Lubrication and wear in joints. Sector, London, 1969) and takes into account the fluid transport across the articular cartilage using Darcy’s equation to depict the synovial fluid motion through a porous cartilage matrix. The human ankle joint is assumed to be cylindrical enabling motion in the sagittal plane only. The proposed model is based on a modified Reynolds equation; its integration allows to obtain a quick assessment on the synovial pressure field showing a good agreement with those obtained numerically (Hlavacek, J Biomech 33:1415–1422, 2000). The analytical integration allows the closed form description of the synovial fluid film force and the calculation of the unsteady gap thickness.

The analysis of the basketball coach speech during the moments of game and pause in relation to the performance in competition

In the area of the professional competition, the coach is a fundamental part in the management of a team and more concretely in the game planning. During the competition, the management of the times of pause and times out as well as the conduct of the coach during the same ones is an aspect to analyze in the sports performance. It is for this that it becomes necessary to know some of the behaviors that turn out to be more frequent by the coach and that are more related to a positive performance of his players. For it there has been realized a study of 7 cases of expert coaches in those that his verbal behavior has observed during 4 games. It has focused on the content of the information only to verbal level, on his meaning. The information that have been obtained in the study shows a major quantity of information elaborated during the pauses of the games and a major tactical content with regard to the moments of game. On the other hand, a relation exists between a major number of questions and a minor number of psychological instructions when the score is adverse, whereas in case of victory, a direct relation does not exist with any category. The rest of categories of the speech do not meet influenced directly for the result, for what it is not possible to consider a direct and immediate relation between the coach verbal behavior during the pauses and the result of the game, except in punctual moments.

Análisis cuantitativo y cualitativo de los momentos críticos en baloncesto = Quantitative and qualitative analysis of the critical moments in basketball

El MC en baloncesto es aquel fenómeno relacionado con el juego que presenta unas características particulares determinadas por la idiosincrasia de un equipo y puede afectar a los protagonistas y por ende al devenir del juego. En la presente Tesis se ha estudiado la incidencia del MC en Liga A.C.B. de baloncesto y para su desarrollo en profundidad se ha planteado dos investigaciones una cuantitativa y otra cualitativa cuya metodología se detalla a continuación: La investigación cuantitativa se ha basado en la técnica de estudio del “Performance analysis”, para ello se han estudiado cuatro temporadas de la Liga A.C.B. (del 2007/08 al 2010/11), tal y como refleja en la bibliografía consultada se han tomado como momentos críticos del juego a los últimos cinco minutos de partidos donde la diferencia de puntos fue de seis puntos y todos los Tiempos Extras disputados, de tal manera que se han estudiado 197 momentos críticos. La contextualización del estudio se ha hecho en función de la variables situacionales “game location” (local o visitante), “team quality” (mejores o peores clasificados) y “competition” (fases de LR y Playoff). Para la interpretación de los resultados se han realizado los siguientes análisis descriptivos: 1) Análisis Discriminante, 2) Regresión Lineal Múltiple; y 3) Análisis del Modelo Lineal General Multivariante. La investigación cualitativa se ha basado en la técnica de investigación de la entrevista semiestructurada. Se entrevistaron a 12 entrenadores que militaban en la Liga A.C.B. durante la temporada 2011/12, cuyo objetivo ha sido conocer el punto de vista que tiene el entrenador sobre el concepto del MC y que de esta forma pudiera dar un enfoque más práctico basado en su conocimiento y experiencia acerca de cómo actuar ante el MC en el baloncesto. Los resultados de ambas investigaciones coinciden en señalar la importancia del MC sobre el resultado final del juego. De igual forma, el concepto en sí entraña una gran complejidad por lo que se considera fundamental la visión científica de la observación del juego y la percepción subjetiva que presenta el entrenador ante el fenómeno, para la cual los aspectos psicológicos de sus protagonistas (jugadores y entrenadores) son determinantes. ABSTRACT The Critical Moment (CM) in basketball is a related phenomenon with the game that has particular features determined by the idiosyncrasies of a team and can affect the players and therefore the future of the game. In this Thesis we have studied the impact of CM in the A.C.B. League and from a profound development two investigations have been raised, quantitative and qualitative whose methodology is as follows: The quantitative research is based on the technique of study "Performance analysis", for this we have studied four seasons in the A.C.B. League (2007/08 to 2010/11), and as reflected in the literature the Critical Moments of the games were taken from the last five minutes of games where the point spread was six points and all overtimes disputed, such that 197 critical moments have been studied. The contextualization of the study has been based on the situational variables "game location" (home or away), "team quality" (better or lower classified) and "competition" (LR and Playoff phases). For the interpretation of the results the following descriptive analyzes were performed: 1) Discriminant Analysis, 2) Multiple Linear Regression Analysis; and 3) Analysis of Multivariate General Linear Model. Qualitative research is based on the technique of investigation of a semi-structured interview. 12 coaches who belonged to the A.C.B. League were interviewed in seasons 2011/12, which aimed to determine the point of view that the coach has on the CM concept and thus could give a more practical approach based on their knowledge and experience about how to deal with the CM in basketball. The results of both studies agree on the importance of the CM on the final outcome of the game. Similarly, the concept itself is highly complex so the scientific view of the observation of the game is considered essential as well as the subjective perception the coach presents before the phenomenon, for which the psychological aspects of their characters (players and coaches) are crucial.

Exploring the origins of topological frustration: Design of a minimally frustrated model of fragment B of protein A

Topological frustration in an energetically unfrustrated off-lattice model of the helical protein fragment B of protein A from Staphylococcus aureus was investigated. This Gō-type model exhibited thermodynamic and kinetic signatures of a well-designed two-state folder with concurrent collapse and folding transitions and single exponential kinetics at the transition temperature. Topological frustration is determined in the absence of energetic frustration by the distribution of Fersht φ values. Topologically unfrustrated systems present a unimodal distribution sharply peaked at intermediate φ, whereas highly frustrated systems display a bimodal distribution peaked at low and high φ values. The distribution of φ values in protein A was determined both thermodynamically and kinetically. Both methods yielded a unimodal distribution centered at φ = 0.3 with tails extending to low and high φ values, indicating the presence of a small amount of topological frustration. The contacts with high φ values were located in the turn regions between helices I and II and II and III, intimating that these hairpins are in large part required in the transition state. Our results are in good agreement with all-atom simulations of protein A, as well as lattice simulations of a three- letter code 27-mer (which can be compared with a 60-residue helical protein). The relatively broad unimodal distribution of φ values obtained from the all-atom simulations and that from the minimalist model for the same native fold suggest that the structure of the transition state ensemble is determined mostly by the protein topology and not energetic frustration.

A Polymer Model for the Structural Organization of Chromatin Loops and Minibands in Interphase Chromosomes

A quantitative model of interphase chromosome higher-order structure is presented based on the isochore model of the genome and results obtained in the field of copolymer research. G1 chromosomes are approximated in the model as multiblock copolymers of the 30-nm chromatin fiber, which alternately contain two types of 0.5- to 1-Mbp blocks (R and G minibands) differing in GC content and DNA-bound proteins. A G1 chromosome forms a single-chain string of loop clusters (micelles), with each loop ∼1–2 Mbp in size. The number of ∼20 loops per micelle was estimated from the dependence of geometrical versus genomic distances between two points on a G1 chromosome. The greater degree of chromatin extension in R versus G minibands and a difference in the replication time for these minibands (early S phase for R versus late S phase for G) are explained in this model as a result of the location of R minibands at micelle cores and G minibands at loop apices. The estimated number of micelles per nucleus is close to the observed number of replication clusters at the onset of S phase. A relationship between chromosomal and nuclear sizes for several types of higher eukaryotic cells (insects, plants, and mammals) is well described through the micelle structure of interphase chromosomes. For yeast cells, this relationship is described by a linear coil configuration of chromosomes.

A model of long-term memory storage in the cerebellar cortex: A possible role for plasticity at parallel fiber synapses onto stellate/basket interneurons

By evoking changes in climbing fiber activity, movement errors are thought to modify synapses from parallel fibers onto Purkinje cells (pf*Pkj) so as to improve subsequent motor performance. Theoretical arguments suggest there is an intrinsic tradeoff, however, between motor adaptation and long-term storage. Assuming a baseline rate of motor errors is always present, then repeated performance of any learned movement will generate a series of climbing fiber-mediated corrections. By reshuffling the synaptic weights responsible for any given movement, such corrections will degrade the memories for other learned movements stored in overlapping sets of synapses. The present paper shows that long-term storage can be accomplished by a second site of plasticity at synapses from parallel fibers onto stellate/basket interneurons (pf*St/Bk). Plasticity at pf*St/Bk synapses can be insulated from ongoing fluctuations in climbing fiber activity by assuming that changes in pf*St/Bk synapses occur only after changes in pf*Pkj synapses have built up to a threshold level. Although climbing fiber-dependent plasticity at pf*Pkj synapses allows for the exploration of novel motor strategies in response to changing environmental conditions, plasticity at pf*St/Bk synapses transfers successful strategies to stable long-term storage. To quantify this hypothesis, both sites of plasticity are incorporated into a dynamical model of the cerebellar cortex and its interactions with the inferior olive. When used to simulate idealized motor conditioning trials, the model predicts that plasticity develops first at pf*Pkj synapses, but with additional training is transferred to pf*St/Bk synapses for long-term storage.

The "allosteric three-site model" of elongation cannot be confirmed in a well-defined ribosome system from Escherichia coli.

For the functional role of the ribosomal tRNA exit (E) site, two different models have been proposed. It has been suggested that transient E-site binding of the tRNA leaving the peptidyl (P) site promotes elongation factor G (EF-G)-dependent translocation by lowering the energetic barrier of tRNA release [Lill, R., Robertson, J. M. & Wintermeyer, W. (1989) EMBO J. 8, 3933-3938]. The alternative "allosteric three-site model" [Nierhaus, K.H. (1990) Biochemistry 29, 4997-5008] features stable, codon-dependent tRNA binding to the E site and postulates a coupling between E and aminoacyl (A) sites that regulates the tRNA binding affinity of the two sites in an anticooperative manner. Extending our testing of the two conflicting models, we have performed translocation experiments with fully active ribosomes programmed with heteropolymeric mRNA. The results confirm that the deacylated tRNA released from the P site is bound to the E site in a kinetically labile fashion, and that the affinity of binding, i.e., the occupancy of the E site, is increased by Mg2+ or polyamines. At conditions of high E-site occupancy in the posttranslocation complex, filling the A site with aminoacyl-tRNA had no influence on the E site, i.e., there was no detectable anticooperative coupling between the two sites, provided that second-round translocation was avoided by removing EF-G. On the basis of these results, which are entirely consistent with our previous results, we consider the allosteric three-site model of elongation untenable. Rather, as proposed earlier, the E site-bound state of the leaving tRNA is a transient intermediate and, as such, is a mechanistic feature of the classic two-state model of the elongating ribosome.

Biennial report of the Fish and Game Commission of the State of Oregon to the Governor and the ... Legislative Assembly.

Report year ends Nov. 30.