Computer-assisted two-dimensional preoperative planning for total hip arthroplasty: clinical evaluation.

The purpose of this study is to clinically validate a new two-dimensional preoperative planning software for cementless total hip arthroplasty (THA). Manual and two-dimensional computer-assisted planning were compared by an independent observer for each of the 30 patients with osteoarthritis who underwent THA. This study showed that there were no statistical differences between the results of both preoperative plans in terms of stem size and neck length (<1 size) and hip rotation center position (<5 mm). Two-dimensional computer-assisted preoperative planning provided successful results comparable to those using the manual procedure, thereby allowing the surgeon to simulate various stem designs easily.

Computer-aided volume measurement of posttraumatic orbits reconstructed with AO titanium mesh plates: accuracy and reliability

PURPOSE: To prospectively evaluate the accuracy and reliability of "freehand" posttraumatic orbital wall reconstruction with AO (Arbeitsgemeinschaft Osteosynthese) titanium mesh plates by using computer-aided volumetric measurement of the bony orbits. METHODS: Bony orbital volume was measured in 12 patients from coronal CT scan slices using OsiriX Medical Image software. After defining the volumetric limits of the orbit, the segmentation of the bony orbital region of interest of each single slice was performed. At the end of the segmentation process, all regions of interest were grouped and the volume was computed. The same procedure was performed on both orbits, and thereafter the volume of the contralateral uninjured orbit was used as a control for comparison. RESULTS: In all patients, the volume data of the reconstructed orbit fitted that of the contralateral uninjured orbit with accuracy to within 1.85 cm3 (7%). CONCLUSIONS: This preliminary study has demonstrated that posttraumatic orbital wall reconstruction using "freehand" bending and placement of AO titanium mesh plates results in a high success rate in re-establishing preoperative bony volume, which closely approximates that of the contralateral uninjured orbit.

Computer-aided system for morphometric mandibular index computation (Using dental panoramic radiographs)

Objective: We propose and validate a computer aided system to measure three different mandibular indexes: cortical width, panoramic mandibular index and, mandibular alveolar bone resorption index. Study Design: Repeatability and reproducibility of the measurements are analyzed and compared to the manual estimation of the same indexes. Results: The proposed computerized system exhibits superior repeatability and reproducibility rates compared to standard manual methods. Moreover, the time required to perform the measurements using the proposed method is negligible compared to perform the measurements manually. Conclusions: We have proposed a very user friendly computerized method to measure three different morphometric mandibular indexes. From the results we can conclude that the system provides a practical manner to perform these measurements. It does not require an expert examiner and does not take more than 16 seconds per analysis. Thus, it may be suitable to diagnose osteoporosis using dental panoramic radiographs.

Design of an Embedded Computer Board for Networking Applications

Tämä diplomityö tehtiin Convergens Oy:lle. Convergens on elektroniikan suunnittelutoimisto, joka on erikoistunut sulautettuihin järjestelmiin sekä tietoliikennetekniikkaan. Diplomityön tavoitteena oli suunnitella tietokonekortti tietoliikennesovelluksia varten asiakkaalle, jolta vaatimusmäärittelyt tulivat. Työ on rajattu koskemaan laitteen prototyypin suunnittelua. Työssä suunnitellaan pääasiassa WLAN-tukiaseman tietokone. Tukiasema onasennettavissa toimistoihin, varastoihin, kauppoihin sekä myös liikkuvaan ajoneuvoon. Suunnittelussa on otettu nämä asiat huomioon, ja laitteen akun pystyy lataamaan muun muassa auton akulla. Langattomat tekniikat ovat voimakkaasti yleistymässä, ja tämän työn tukiasema tarjoaakin varteenotettavan vaihtoehdon lukuisilla ominaisuuksillaan. Mukana on mm. GPS, Bluetooth sekä Ethernet-valmius. Langattomien tekniikoiden lisäksi myös sulautetut järjestelmät ovat voimakkaasti yleistymässä, ja nykyään mikroprosessoreita löytääkin lähesmistä vain. Tässä projektissa käytetty prosessori on nopeutensa puolesta kilpailukykyinen, ja siitä löytyy useita eri rajapintoja. Jatkossa tietokonekortille on myös tulossa WiMAX-tuki, joka lisää tukiaseman tulevaisuuden arvoa asiakkaalle. Projektiin valittu Freescalen MPC8321E-prosessori on PowerPC-arkkitehtuuriin perustuva ja juuri markkinoille ilmestynyt. Tämä toi mukanaan lisähaasteen, sillä kyseisestä prosessorista ei ollut vielä kaikkea tietoa saatavilla. Mekaniikka toi omat haasteensa mukanaan, sillä se rajoitti piirilevyn koonniin, että ylimääräistä piirilevytilaa ei juurikaan jäänyt. Tämän takia esimerkiksi DDR-muistit olivat haastavia reitittää, sillä muistivetojen on oltava melko samanpituisia keskenään. Käyttöjärjestelmänä projektissa käytetään Linuxia. Suunnittelu alkoi keväällä 2007 ja toimiva prototyyppi oli valmis alkusyksystä. Prototyypin testaus osoitti, että tietokonekortti kykenee täyttämään kaikki asiakkaan vaatimukset. Prototyypin testauksessa löytyneet viat ja optimoinnit on tarkoitus korjata tuotantomalliin, joten se antaa hyvän pohjan jatkosuunnittelua varten.

Seguiment de les extremitats dels ratolins i les vibrisses del musell

El present TFM té per objectiu aplicar tècniques d'intel·ligència artificial per realitzar el seguiment de les extremitats dels ratolins i les vibrisses del seu musell. Aquest objectiu es deriva de la necessitat per part dels realitzadors d'experiments optogenètics de registrar els moviments dels ratolins.

Supervised localimage feature detection

This thesis is about detection of local image features. The research topic belongs to the wider area of object detection, which is a machine vision and pattern recognition problem where an object must be detected (located) in an image. State-of-the-art object detection methods often divide the problem into separate interest point detection and local image description steps, but in this thesis a different technique is used, leading to higher quality image features which enable more precise localization. Instead of using interest point detection the landmark positions are marked manually. Therefore, the quality of the image features is not limited by the interest point detection phase and the learning of image features is simplified. The approach combines both interest point detection and local description into one phase for detection. Computational efficiency of the descriptor is therefore important, leaving out many of the commonly used descriptors as unsuitably heavy. Multiresolution Gabor features has been the main descriptor in this thesis and improving their efficiency is a significant part. Actual image features are formed from descriptors by using a classifierwhich can then recognize similar looking patches in new images. The main classifier is based on Gaussian mixture models. Classifiers are used in one-class classifier configuration where there are only positive training samples without explicit background class. The local image feature detection method has been tested with two freely available face detection databases and a proprietary license plate database. The localization performance was very good in these experiments. Other applications applying the same under-lying techniques are also presented, including object categorization and fault detection.

Experimental insights into deformation dynamics and intermittency in rapid granular shear flows

This work concerns the experimental study of rapid granular shear flows in annular Couette geometry. The flow is induced by continuous driving of the horizontal plate at the top of the granular bed in an annulus. The compressive pressure, driving torque, instantaneous bed height and rotational speed of the shearing plate are measured. Moreover, local stress fluctuations are measured in a medium made of steel spheres 2 and 3 mm in diameter. Both monodisperse packing and bidisperse packing are investigated to reveal the influence of size diversity in intermittent features of granular materials. Experiments are conducted in an annulus that can contain up to 15 kg of spherical steel balls. The shearing granular medium takes place via the rotation of the upper plate which compresses the material loaded inside the annulus. Fluctuations of compressive force are locally measured at the bottom of the annulus using a piezoelectric sensor. Rapid shear flow experiments are pursued at different compressive forces and shear rates and the sensitivity of fluctuations are then investigated by different means through monodisperse and bidisperse packings. Another important feature of rapid granular shear flows is the formation of ordered structures upon shearing. It requires a certain range for the amount of granular material (uniform size distribution) loaded in the system in order to obtain stable flows. This is studied more deeply in this thesis. The results of the current work bring some new insights into deformation dynamics and intermittency in rapid granular shear flows. The experimental apparatus is modified in comparison to earlier investigations. The measurements produce data for various quantities continuously sampled from the start of shearing to the end. Static failure and dynamic shearing ofa granular medium is investigated. The results of this work revealed some important features of failure dynamics and structure formation in the system. Furthermore, some computer simulations are performed in a 2D annulus to examine the nature of kinetic energy dissipation. It is found that turbulent flow models can statistically represent rapid granular flows with high accuracy. In addition to academic outcomes and scientific publications our results have a number of technological applications associated with grinding, mining and massive grain storages.

Mass transfer and particleinteractions in granular systems and suspension flows

The purpose of this study was to investigate some important features of granular flows and suspension flows by computational simulation methods. Granular materials have been considered as an independent state ofmatter because of their complex behaviors. They sometimes behave like a solid, sometimes like a fluid, and sometimes can contain both phases in equilibrium. The computer simulation of dense shear granular flows of monodisperse, spherical particles shows that the collisional model of contacts yields the coexistence of solid and fluid phases while the frictional model represents a uniform flow of fluid phase. However, a comparison between the stress signals from the simulations and experiments revealed that the collisional model would result a proper match with the experimental evidences. Although the effect of gravity is found to beimportant in sedimentation of solid part, the stick-slip behavior associated with the collisional model looks more similar to that of experiments. The mathematical formulations based on the kinetic theory have been derived for the moderatesolid volume fractions with the assumption of the homogeneity of flow. In orderto make some simulations which can provide such an ideal flow, the simulation of unbounded granular shear flows was performed. Therefore, the homogeneous flow properties could be achieved in the moderate solid volume fractions. A new algorithm, namely the nonequilibrium approach was introduced to show the features of self-diffusion in the granular flows. Using this algorithm a one way flow can beextracted from the entire flow, which not only provides a straightforward calculation of self-diffusion coefficient but also can qualitatively determine the deviation of self-diffusion from the linear law at some regions nearby the wall inbounded flows. Anyhow, the average lateral self-diffusion coefficient, which was calculated by the aforementioned method, showed a desirable agreement with thepredictions of kinetic theory formulation. In the continuation of computer simulation of shear granular flows, some numerical and theoretical investigations were carried out on mass transfer and particle interactions in particulate flows. In this context, the boundary element method and its combination with the spectral method using the special capabilities of wavelets have been introduced as theefficient numerical methods to solve the governing equations of mass transfer in particulate flows. A theoretical formulation of fluid dispersivity in suspension flows revealed that the fluid dispersivity depends upon the fluid properties and particle parameters as well as the fluid-particle and particle-particle interactions.

Learning through Computer Model Improvisations

It has been convincingly argued that computer simulation modeling differs from traditional science. If we understand simulation modeling as a new way of doing science, the manner in which scientists learn about the world through models must also be considered differently. This article examines how researchers learn about environmental processes through computer simulation modeling. Suggesting a conceptual framework anchored in a performative philosophical approach, we examine two modeling projects undertaken by research teams in England, both aiming to inform flood risk management. One of the modeling teams operated in the research wing of a consultancy firm, the other were university scientists taking part in an interdisciplinary project experimenting with public engagement. We found that in the first context the use of standardized software was critical to the process of improvisation, the obstacles emerging in the process concerned data and were resolved through exploiting affordances for generating, organizing, and combining scientific information in new ways. In the second context, an environmental competency group, obstacles were related to the computer program and affordances emerged in the combination of experience-based knowledge with the scientists' skill enabling a reconfiguration of the mathematical structure of the model, allowing the group to learn about local flooding.

MPRO-Spanish: development and experiments with a linguistic parser for Spanish texts

This paper describes the main features and present results of MPRO-Spanish, a parser for morphological and syntactic analysis of unrestricted Spanish text developed at the IAI1. This parser makes direct use of X-phrase structure rules to handle a variety of patterns from derivational morphology and syntactic structure. Both analyses, morphological and syntactic, are realised by two subsequent modules. One module analyses and disambiguates the source words at morphological level while the other consists of a series of programs and a deterministic, procedural and explicit grammar. The article explains the main features of MPRO and resumes some of the experiments on some of its applications, some of which still being implemented like the monolingual and bilingual term extraction while others need further work like indexing. The results and applications obtained so far with simple and relatively complex sentences give us grounds to believe in its reliability.

Comblike poly(a-alkyl g glutamate)s: computer simulation studies of an intermediate thermal phase.

Monte Carlo (MC) simulations have been used to study the structure of an intermediate thermal phase of poly(R-octadecyl ç,D-glutamate). This is a comblike poly(ç-peptide) able to adopt a biphasic structure that has been described as a layered arrangement of backbone helical rods immersed in a paraffinic pool of polymethylene side chains. Simulations were performed at two different temperatures (348 and 363 K), both of them above the melting point of the paraffinic phase, using the configurational bias MC algorithm. Results indicate that layers are constituted by a side-by-side packing of 17/5 helices. The organization of the interlayer paraffinic region is described in atomistic terms by examining the torsional angles and the end-to-end distances for the octadecyl side chains. Comparison with previously reported comblike poly(â-peptide)s revealed significant differences in the organization of the alkyl side chains.

Relaxation and derelaxation of pure and hydrogenated amorphous silicon during thermal annealing experiments

The structural relaxation of pure amorphous silicon a-Si and hydrogenated amorphous silicon a-Si:H materials, that occurs during thermal annealing experiments, has been analyzed by Raman spectroscopy and differential scanning calorimetry. Unlike a-Si, the heat evolved from a-Si:H cannot be explained by relaxation of the Si-Si network strain but it reveals a derelaxation of the bond angle strain. Since the state of relaxation after annealing is very similar for pure and hydrogenated materials, our results give strong experimental support to the predicted configurational gap between a-Si and crystalline silicon.