bluuebunny/crossref_metadata_2025 huggingface dataset:
MODELLING AND SIMULATION OF A NEUROPHYSIOLOGICAL EXPERIMENT BY SPATIO-TEMPORAL POINT PROCESSES
Authors: Beneš Viktor , Frcalová Blažena
Published: July 2011

We present a stochastic model of an experimentmonitoring the spiking activity of a place cell of hippocampus of an experimental animal moving in an arena. Doubly stochastic spatio-temporal point process is used to model and quantify overdispersion. Stochastic intensity is modelled by a Lévy based random field while the animal path is simplified to a discrete random walk. In a simulation study first a method suggested previously is used. Then it is shown that a solution of the filtering problem yields the desired inference to the random intensity. Two approaches are suggested and the new one based on finite point process density is applied. Using Markov chain Monte Carlo we obtain numerical results from the simulated model. The methodology is discussed.
A TESSELLATION MODEL FOR CRACK PATTERNS ON SURFACES
Authors: Nagel Werner , Mecke Joseph , Ohser Joachim , Weiss Viola
Published: July 2011

This paper presents a model of random tessellations that reflect several features of crack pattern. There are already several theoretical results derivedwhich indicate that thismodel can be an appropriate referencemodel. Some potential applications are presented in a tentative statistical study.
A NEW METHOD FOR ESTIMATING THE 3D SIZE-DISTRIBUTIONCURVE OF FRAGMENTED ROCKS OUT OF 2D IMAGES
Authors: Outal Souhaïl , Jeulin Dominique , Schleifer Jacques
Published: July 2011

Image analysis of rock fragmentation is used in mines and quarries to control the quality of blasting. Obtained information is the particle-size-distribution curve relating volume-proportions to the sizes of fragments. Calculation by image analysis of this particle-size-distribution is carried out in several steps, and each step has its inherent limitations. We will focus in this paper on one of themost crucial steps: reconstructing the volumes (3D). For the 3D-step, we have noticed that, due to the current acquisition method, there is no correlation between the average grey level of surfaces of the fragments and their third dimension. Consequently volumes (3D) as well as the sizes (1D) has to be calculated indirectly from the extracted projected areas of the visible fragments of images. For this purpose, we have built in laboratory a set of images of fragmented rocks resulting from blasting. Moreover, several tests based on comparisons between image analysis and screening measurements were carried out. A new stereological method, based on the comparison of the densities of probability (histograms) of the samemeasurements (with very weak covering and overlapping)was elaborated. It allows us to estimate correctly, for a given type of rock, two intrinsic laws weighing the projected areas distribution in order to predict the volumic distribution.
MICROCT AND PREPARATION OF ß-TCP GRANULAR MATERIAL BY THE POLYURETHANE FOAM METHOD
Authors: Filmon Robert , Retailleau-Gaborit Nadine , Brossard Guenaelle , Grizon-Pascaretti Florence , Basle Michel Felix , Chappard Daniel
Published: July 2011

Commercial ß-tricalcium phosphate (ß-TCP) is commercialy available in granules manufactured by sintering of powders. We have evaluated the different steps of the manufacturing process of ß-TCP ceramics granules prepared from blocks obtained with the polyurethane foam technology. Three types of slurry were prepared with 10, 15 and 25 g of ß-TCP per gram of polyurethane foam. Analysis was done by scanning electron microscopy, EDX, Raman spectroscopy and microcomputed tomography combined with image analysis. A special algorithm was used to identify the internal microporosity (created by the calcination of the foam) from the internal macroporosity due to the spatial repartition of the material. The low ß-TCP dosages readily infiltrated the foam and the slurry was deposited along the polymer rods. On the contrary, the highest concentration produced inhomogeneous infiltrated blocks and foam cavities appeared completely filled in some areas. 2D microcomputed sections and reconstructed 3D models evidenced this phenomenon and the frequency distribution of the thickness and separation of material trabeculae confirmed the heterogeneity of the distribution. When crushed, blocks prepared with the 25 g slurry provided the largest and irregular granulates.
A STEREOLOGICAL UNFOLDING METHOD FOR THE STUDY OF THE MITOCHONDRIAL NETWORK
Authors: Flynn Daniel Christopher , Nulton James Darwin , Salamon Peter , Frey Terrence Gene , Rabinovitch Avinoam , Sun Mei Guo , Baljon Arlette Rose Cornelia
Published: July 2011

When the mitochondrial network within the cell is in a fragmented state, it resembles a spatial distribution of prolate spheroids of various shapes, sizes and orientations. This paper presents a maximum-likelihood scheme for inferring the distribution of spheroidal shapes, sizes and orientations from the observed distribution of elliptical sections. We also present a parametric bootstrap suitable for inferring confidence intervals for the parameters describing the shape and size distribution of the spheroids.
PLACENTAL STEREOLOGY: SPANNING THE LEVELS FROM MOLECULE TO WHOLE ORGAN
Authors: Mayhew Terry M
Published: July 2011

Stereology can provide hard (functionally-relevant) quantitative information at different levels of 3D structural organization. My researches have applied established methods to study organ function and developed novel methods to study subcellular localization of marker probes. We have studied whole-organ function (passive diffusion) in the human placenta and quantified various processes at tissue and subcellular levels and in normal and complicated pregnancies. Fetoplacental angiogenesis and villous growth and maturation involve phased changes particularly around mid-gestation. Growth is associated with increased numbers of cells or nuclei and counts have shown that villous trophoblast continuously renews itself via cytotrophoblast (CT) proliferation and recruitment and syncytiotrophoblast (ST) differentiation and extrusion. Integration of these processes results in changes in total oxygen (O2) diffusive conductance which match the growing fetal mass. Similar processes occur during development of the mouse placenta and at least some are compromised in human pregnancies. For example: [a] in pure pre-eclampsia (PE), villous and fetoplacental vascular volumes and surfaces are similar to those seen in uncomplicated pregnancies but reduced in pure intrauterine growth restriction (IUGR) and in PE+IUGR; [b] trophoblast extrusion is accelerated in PE and IUGR but the latter exhibits reduced CT proliferation and this perturbed steady state leads to smaller trophoblast volumes and surfaces; [c] O2 diffusive conductances alter in various pregnancy complications, including IUGR and PE+IUGR; [d] fetal weight is diminished, but diffusive transport increases, in placentas from mice exposed to urban air pollution. Finally, innovations in quantitative immunoelectron microscopy (immunoEM) have produced a portfolio of methods for revealing non-random distributions of marker gold particles in different cellular compartments and for testing whether patterns shift following experimental manipulation. Recently, the methods have been extended to study tissue and cellular distributions of nanoparticles.
3D DIRECTIONAL MATHEMATICAL MORPHOLOGY FOR ANALYSIS OF FIBER ORIENTATIONS
Authors: Altendorf Hellen , Jeulin Dominique
Published: July 2011

In this paper we present algorithms for measuring local characteristics of random fiber systems. The calculation of the local directions and radii is based on directional distance transforms and evaluation of the inertia moments and axes of the resulting extremities of the centralized, directed chords. The method provides continuous results while minimizing the runtime by using few sampled directions. Furthermore several steps of improvement for the computation of orientation and radius information are presented. The algorithms are evaluated using synthetic data and applied to images of realmicrostructures obtained by computer tomography.
CAPACITY DISTRIBUTIONS IN SPATIAL STOCHASTIC MODELS FOR TELECOMMUNICATION NETWORKS
Authors: Voss Florian , Gloaguen Catherine , Schmidt Volker
Published: July 2011

We consider the stochastic subscriber line model as a spatial stochastic model for telecommunication networks and we are interested in the evaluation of the required capacities at different locations of the network in order to provide, in fine, an estimation of the cable system which has to be installed. In particular, we consider hierarchical telecommunication networks with higher–level components (HLC) and lower–level components (LLC) located on the road system underlying the network. The cable paths are modeled by shortest paths along the edge set of a stationary random tessellation, whereas both HLC and LLC are modeled by Cox processes concentrated on the edges of this tessellation. We then introduce the notion of capacity which depends on the length of some subtree on the edge set of the underlying tessellation. Moreover, we investigate estimators for the density and distribution function of the typical length of this subtree which can be computed based on Monte Carlo simulations of the typical serving zone. In a numerical study, the density of the typical subtree length is determined for different specific models.
ERROR BOUNDS FOR SURFACE AREA ESTIMATORS BASED ON CROFTON’S FORMULA
Authors: Kiderlen Markus , Meschenmoser Daniel
Published: July 2011

According to Crofton's formula, the surface area S(A) of a sufficiently regular compact set A in Rd is proportional to the mean of all total projections pA (u) on a linear hyperplane with normal u, uniformly averaged over all unit vectors u. In applications, pA (u) is only measured in k directions and the mean is approximated by a finite weighted sum bS(A) of the total projections in these directions. The choice of the weights depends on the selected quadrature rule. We define an associated zonotope Z (depending only on the projection directions and the quadrature rule), and show that the relative error bS (A)/S (A) is bounded from below by the inradius of Z and from above by the circumradius of Z. Applying a strengthened isoperimetric inequality due to Bonnesen, we show that the rectangular quadrature rule does not give the best possible error bounds for d =2. In addition, we derive asymptotic behavior of the error (with increasing k) in the planar case. The paper concludes with applications to surface area estimation in design-based digital stereology where we show that the weights due to Bonnesen's inequality are better than the usual weights based on the rectangular rule and almost optimal in the sense that the relative error of the surface area estimator is very close to the minimal error.
MESH FREE ESTIMATION OF THE STRUCTURE MODEL INDEX
Authors: Ohser Joachim , Redenbach Claudia , Schladitz Katja
Published: July 2011

The structure model index (SMI) is a means of subsuming the topology of a homogeneous random closed set under just one number, similar to the isoperimetric shape factors used for compact sets. Originally, the SMI is defined as a function of volume fraction, specific surface area and first derivative of the specific surface area, where the derivative is defined and computed using a surface meshing. The generalised Steiner formula yields however a derivative of the specific surface area that is – up to a constant – the density of the integral of mean curvature. Consequently, an SMI can be defined without referring to a discretisation and it can be estimated from 3D image data without need to mesh the surface but using the number of occurrences of 2×2×2 pixel configurations, only. Obviously, it is impossible to completely describe a random closed set by one number. In this paper, Boolean models of balls and infinite straight cylinders serve as cautionary examples pointing out the limitations of the SMI. Nevertheless, shape factors like the SMI can be valuable tools for comparing similar structures. This is illustrated on real microstructures of ice, foams, and paper.
SIZE OF BOEHMITE NANOPARTICLES BY TEM IMAGES ANALYSIS
Authors: Moreaud Maxime , Revel Renaud , Jeulin Dominique , Morard Vincent
Published: July 2011

Transition aluminas, and especially the gamma type, are largely used as catalyst supports in refining and petrochemicals. Most studies focus on properties resulting from material texture and casting (specific surface, porous volume, pore shape and diameter). However, surface properties of alumina should be considered as well, as the catalytic activity is tightly related to the structure of exposed crystalline faces. As γ alumina results from controlled thermal treatment of boehmite γ-AlOOH by a topotactic transformation, the nature of exposed crystalline planes is related to the starting material. Therefore, the synthesis of the oxihydroxide γ-AlOOH, and especially size and shape of these particles, is critical in determining the relevant surface properties. Unlike often aggregated alumina, boehmite nanoparticles can be observed by TEM. Analysis of these TEM images can be performed to estimate the size of the boehmite nanoparticles. Information about morphology of the nanoparticles is obtained by the analysis of the covariance, modeling micrographs by a dilution model.
MODELING OF MULTISCALE POROUS MEDIA
Authors: Biswal Bibhu , Øren Pål-Eric , Held Rudolf J , Bakke Stig , Hilfer Rudolf
Published: July 2011

A stochastic geometrical modeling method for reconstructing three dimensional pore scale microstructures of multiscale porous media is presented. In this method the porous medium is represented by a random but spatially correlated structure of objects placed in the continuum. The model exhibits correlations with the sedimentary textures, scale dependent intergranular porosity over many decades, vuggy or dissolution porosity, a percolating pore space, a fully connected matrix space, strong resolution dependence and wide variability in the permeabilities and other properties. The continuum representation allows discretization at arbitrary resolutions providing synthetic micro-computertomographic images for resolution dependent fluid flow simulation. Model implementations for two different carbonate rocks are presented. The method can be used to generate pore scale models of a wide class of multiscale porous media.
LABELING OF N-DIMENSIONAL IMAGES WITH CHOOSABLE ADJACENCY OF THE PIXELS
Authors: Sandfort Kai , Ohser Joachim
Published: July 2011

The labeling of discretized image data is one of the most essential operations in digital image processing. The notions of an adjacency system of pixels and the complementarity of two such systems are crucial to guarantee consistency of any labeling routine. In to date's publications, this complementarity usually is defined using discrete versions of the Jordan-Veblen curve theorem and the Jordan-Brouwer surface theorem for 2D and 3D images, respectively. In contrast, we follow here an alternative concept, which relies on a consistency relation for the Euler number. This relation and all necessary definitions are easily stated in a uniform manner for the n-dimensional case. For this, we present identification and convergence results for complementary adjacency systems, supplemented by examples for the 3D case. Next, we develop a pseudo-code for a general labeling algorithm. The application of such an algorithm should be assessed with regard to our preceding considerations. A benchmark and a thorough discussion finish our article.
IMAGE SEGMENTATION: A WATERSHED TRANSFORMATION ALGORITHM
Authors: Belaid Lamia Jaafar , Mourou Walid
Published: July 2011

The goal of this work is to present a new method for image segmentation using mathematicalmorphology. The approach used is based on the watershed transformation. In order to avoid an oversegmentation, we propose to adapt the topological gradient method. The watershed transformation combined with a fast algorithm based on the topological gradient approach gives good results. The numerical tests obtained illustrate the efficiency of our approach for image segmentation.
SECOND MOMENT MEASURE AND K-FUNCTION FOR PLANAR STIT TESSELLATIONS
Authors: Weiss Viola , Ohser Joachim , Nagel Werner
Published: July 2011

For STIT tessellations – stationary tessellations that are stable under the operation iteration of tessellations – the second-ordermeasure of the edge system is studied. A result is that this measure coincides with that one of a Boolean segment process. In the isotropic case an explicit formula for the pair-correlation function is given. An estimator for the covariance function of the edge length measure is derived and adapted to digitized images of tessellations. For m pixels of an image the algorithm is of complexity O(mlogm).
CONVEX BODIES AND GAUSSIAN PROCESSES
Authors: Vitale Richard A
Published: July 2011

For several decades, the topics of the title have had a fruitful interaction. This survey will describe some of these connections, including the GB/GC classification of convex bodies, Ito-Nisio singularities from a geometric viewpoint, Gaussian representation of intrinsic volumes, theWills functional in a Gaussian context, and inequalities.
NEW MEAN VALUES FOR HOMOGENEOUS SPATIAL TESSELLATIONS THAT ARE STABLE UNDER ITERATION
Authors: Thäle Christoph , Weiss Viola
Published: July 2011

Homogeneous random tessellations in the 3-dimensional Euclidean space are considered that are stable under iteration – STIT tessellations. A classification of vertices, segments and flats is introduced and a couple of new metric and topological mean values for them and for the typical cell are calculated. They are illustrated by two examples, the isotropic and the cuboid case. Several extremum problems for these mean values are solved with the help of techniques from convex geometry by introducing an associated zonoid for STIT tessellations.
SEMANTIC IMAGE ANALYSIS USING A SYMBOLIC NEURAL ARCHITECTURE
Authors: Kollia Ilianna , Simou Nikolaos , Stafylopatis Andreas , Kollias Stefanos
Published: July 2011

Image segmentation and classification are basic operations in image analysis and multimedia search which have gained great attention over the last few years due to the large increase of digital multimedia content. A recent trend in image analysis aims at incorporating symbolic knowledge representation systems and machine learning techniques. In this paper, we examine interweaving of neural network classifiers and fuzzy description logics for the adaptation of a knowledge base for semantic image analysis. The proposed approach includes a formal knowledge component, which, assisted by a reasoning engine, generates the a-priori knowledge for the image analysis problem. This knowledge is transferred to a kernel based connectionist system, which is then adapted to a specific application field through extraction and use of MPEG-7 image descriptors. Adaptation of the knowledge base can be achieved next. Combined segmentation and classification of images, or video frames, of summer holidays, is the field used to illustrate the good performance of the proposed approach.
CONTENT-BASED AUTOFOCUSING IN AUTOMATED MICROSCOPY
Authors: Hamm Peter , Schulz Janina , Englmeier Karl-Hans
Published: July 2011

Autofocusing is the fundamental step when it comes to image acquisition and analysis with automated microscopy devices. Despite all efforts that have been put into developing a reliable autofocus system, recent methods still lack robustness towards different microscope modes and distracting artefacts. This paper presents a novel automated focusing approach that is generally applicable to different microscope modes (bright-field, phase contrast, Differential Interference Contrast (DIC) and fluorescence microscopy). The main innovation consists in a Content-based focus search that makes use of a priori knowledge about the observed objects by employing local object features and Boosted Learning. Hence, this method turns away from common autofocus approaches that apply solely whole image frequency measurements to obtain the focus plane. Thus, it is possible to exclude artefacts from being brought into focus calculation as well as locating the in-focus layer of specific microscopic objects.
ADVANCES IN MULTIDIMENSIONAL SIZE THEORY
Authors: Cerri Andrea , Frosini Patrizio
Published: July 2011

Size Theory was proposed in the early 90's as a geometrical/topological approach to the problem of Shape Comparison, a very lively research topic in the fields of Computer Vision and Pattern Recognition. The basic idea is to discriminate shapes by comparing shape properties that are provided by continuous functions valued in R, called measuring functions and defined on topological spaces associated to the objects to be studied. In this way, shapes can be compared by using a descriptor named size function, whose role is to capture the features described by measuring functions and represent them in a quantitative way. However, a common scenario in applications is to deal with multidimensional information. This observation has led to considering vector-valued measuring functions, and consequently the multidimensional extension of size functions, namely the k-dimensional size functions. In this work we survey some recent results about size functions in this multidimensional setting, with particular reference to the localization of their discontinuities.
COMBINING WLI AND SEM TECHNIQUES TO OBTAIN A 4D SURFACE IMAGE OF A ppHDMSO/AlCeO3 NANOCOMPOSITE
Authors: Buchheit Olivier , Arnoult Claire , Eddoumy Fatima , Frari Doriane Del , Martino Jean Di , Ruch David
Published: July 2011

Compositional images from a SEM (scanning electron microscope) are sometimes complemented by quantitative topographical data from devices such as an AFM (atomic force microscope) or WLI (white light interferometer). Indeed, even if a SEM could provide both kinds of information (composition and topography), the topographical data are incomplete because the SEM does not allow measuring the vertical dimension (i.e., perpendicular to the measurement plane). Thus these two kinds of information are usually measured using two different techniques, and at different locations on the sample. Mean values of surface composition are then linked to mean values of topography, and as a consequence this approach does not allow precisely linking a local topographical peak to its corresponding composition. The present work deals with a SEM/WLI combination methodology, based on the characterization, at the same location, of a nanocomposite (nanoparticles of AlCeO3 dispersed in a plasma-polymerized hexamethyldisiloxane ppHMDSO matrix and deposited by atmospheric plasma on a glass substrate) developed for improving anticorrosion properties. SEM images allow the supposition that the protuberances (peaks) observed on the surface of a specimen are linked to the nanoparticles dispersed in the polymer coating, but this link is not fully convincing. Thanks to a precise localization method, SEM compositional data and WLI topographical data are here measured at the same location. The recombination of both signals to form a 4D image (3D geometry and 1D composition) allows linking protuberances to nanoparticles aggregates without ambiguity. This composite image appears to be an interesting new tool (at the scale of observation, i.e., hundreds of micrometers) for the study of nanostructured coatings.
STRATEGY ON SIMULATION OF ARBITRARY-SHAPED CEMENT GRAINS IN CONCRETE
Authors: He Huan , Guo Zhanqi , Stroeven Piet , Stroeven Martijn , Sluys Lambertus Johannes
Published: July 2011

The shape of cement particles plays an important role in the hydration process due to surface dissolution and hardening process. Nevertheless, a spherical particle shape is normally assumed in conventional simulation systems, because of the inherent simplification in algorithm formulations and corresponding reduced computer time, however, at the cost of possibly biased simulation results. Recently, some reference cement was analyzed by X-ray micro-tomography. The results provide a real experimental database of this cement that yields valuable parameters for simulation of cement hydration. A shape analysis study was conducted with some simpler shape solutions, whereby the X-ray micro-tomography results served as a reference. Based on this analysis, a simulation strategy is proposed as a preferred approach to cement particle simulation. The generation of the densely packed microstructure of fresh cement paste in this study was conducted by using an advanced discrete element method (DEM).
INDIRECT MEASURES OF NEUROPROTECTION ARE PARAMETERS TO AVOID: EXAMPLES FROM RESEARCH ON NEONATAL RAT HYPOXIA-ISCHEMIA
Authors: Oorschot Dorothy E
Published: July 2011

The use of indirect measures of neuronal injury or neuroprotection, such as brain weight or the neuronal density of neurons, can lead to misinterpretations of biological processes. The use of modern stereological methods to directly measure the absolute number of surviving neurons generally yields more reliable conclusions. The aim of this review is to provide some worked examples of this principle. The worked examples are obtained from research completed over the past 13 years on the investigation of potential neuroprotective therapies for moderate brain injury after neonatal hypoxia-ischemia in the rat.
FAST COMPUTATION OF ALL PAIRS OF GEODESIC DISTANCES
Authors: Noyel Guillaume , Angulo Jesús , Jeulin Dominique
Published: July 2011

Computing an array of all pairs of geodesic distances between the pixels of an image is time consuming. In the sequel, we introduce new methods exploiting the redundancy of geodesic propagations and compare them to an existing one. We show that our method in which the source point of geodesic propagations is chosen according to its minimum number of distances to the other points, improves the previous method up to 32 % and the naive method up to 50 % in terms of reduction of the number of operations.
TESTING HISTOLOGICAL IMAGES OF MAMMARY TISSUES ON COMPATIBILITY WITH THE BOOLEAN MODEL OF RANDOM SETS
Authors: Mrkvička Tomáš , Mattfeldt Torsten
Published: July 2011

Methods for testing the Boolean model assumption from binary images are briefly reviewed. Two hundred binary images of mammary cancer tissue and 200 images of mastopathic tissue were tested individually on the Boolean model assumption. In a previous paper, it had been found that a Monte Carlo method based on the approximation of the envelopes by a multi-normal distribution with the normalized intrinsic volume densities of parallel sets as a summary statistics had the highest power for this purpose. Hence, this method was used here as its first application to real biomedical data. It was found that mastopathic tissue deviates from the Boolean model significantly more strongly than mammary cancer tissue does.
COMPUTATION OF THE PERIMETER OF MEASURABLE SETS VIA THEIR COVARIOGRAM. APPLICATIONS TO RANDOM SETS
Authors: Galerne Bruno
Published: July 2011

The covariogram of a measurable set A ⊂ Rd is the function gA which to each y ∈ Rd associates the Lebesgue measure of A ∩ (y + A). This paper proves two formulas. The first equates the directional derivatives at the origin of gA to the directional variations of A. The second equates the average directional derivative at the origin of gA to the perimeter of A. These formulas, previously known with restrictions, are proved for any measurable set. As a by-product, it is proved that the covariogram of a set A is Lipschitz if and only if A has finite perimeter, the Lipschitz constant being half the maximal directional variation. The two formulas have counterparts for mean covariogram of random sets. They also permit to compute the expected perimeter per unit volume of any stationary random closed set. As an illustration, the expected perimeter per unit volume of stationary Boolean models having any grain distribution is computed.
GENERALIZED FRACTAL TRANSFORMS AND SELF-SIMILARITY: RECENT RESULTS AND APPLICATIONS
Authors: La Torre Davide , Vrscay Edward R.
Published: July 2011

Most practical as well as theoretical works in image processing and mathematical imaging consider images as real-valued functions, u : X → ℝg, where X denotes the base space or pixel space over which the images are defined and ℝg ⊂ ℝ is a suitable greyscale space. A variety of function spaces ℱ(X) may be considered depending on the application. Fractal image coding seeks to approximate an image function as a union of spatially-contracted and greyscale-modified copies of subsets of itself, i.e., u ≈ Tu, where T is the so-called Generalized Fractal Transform (GFT) operator. The aim of this paper is to show some recent developments of the theory of generalized fractal transforms and how they can be used for the purpose of image analysis (compression, denoising). This includes the formulation of fractal transforms over various spaces of multifunctions, i.e., set-valued and measure-valued functions. The latter may be useful in nonlocal image processing.
SEGMENTATION OF ANATOMICAL STRUCTURES BY CONNECTED STATISTICAL MODELS
Authors: Bukovec Marko , Likar Boštjan , Pernuš Franjo
Published: July 2011

This paper presents a framework for the segmentation of anatomical structures in medical imagery by connected statistical models. The framework is based on three types of models: first, generic models which operate directly on image intensities, second, connecting models that impose restrictions on the spatial relationship of generic models, and third, a supervising model that represents an arbitrary number of generic and connecting models. In this paper, the statistical model of appearance is used as the generic model, whiles the statistical model of topology, obtained by applying principal component analysis (PCA) on aligned pose and shape parameters of the generic model, is used as the connecting model. The performance of such connected statistical model is demonstrated on anterior-posterior (AP) X-ray images of the hips and pelvis and compared to the modelling by one and six unconnected generic models. The most accurate and robust results were obtained by two-level hierarchical modelling, wherein connected statistical models were used first, followed by unconnected statistical models.
Does obesity predict knee pain over fourteen years in women, independently of radiographic changes?
Authors: Goulston Lyndsey M. , Kiran A. , Javaid M. K. , Soni A. , White K. M. , Hart D. J. , Spector T. D. , Arden N. K.
Published: July 2011

Objective

To examine longitudinal patterns in body mass index (BMI) over 14 years and its association with knee pain in the Chingford Study.

Methods

We studied a total of 594 women with BMI data from clinic visits at years (Y) 1, 5, 10, and 15. Knee pain at Y15 was assessed by questionnaire. Associations between BMI over 14 years and knee pain at Y15 were examined using logistic regression.

Results

BMI significantly increased from Y1 to Y15 (P < 0.0005) with medians (interquartile ranges) of 24.5 kg/m2 (22.5–27.2 kg/m2) and 26.5 kg/m2 (23.9–30.1 kg/m2), respectively. At Y15, 45.1% of subjects had knee pain. A greater BMI at Y1 (odds ratio [OR] 1.34, 95% confidence interval [95% CI] 1.05–1.69), at Y15 (OR 1.34, 95% CI 1.10–1.61), and change in BMI over 15 years (OR 1.40, 95% CI 1.00–1.93) were significant predictors of knee pain at Y15 (P < 0.05). BMI change was associated with bilateral (OR 1.61, 95% CI 1.05–1.76, P = 0.024) but not unilateral knee pain (OR 1.22, 95% CI 0.73–1.76, P = 0.298). The association between BMI change and knee pain was independent of radiographic knee osteoarthritis (OA). The strength of association between BMI and knee pain at Y15 was similar during followup measurements.

Conclusion

Over 14 years, a higher BMI predicts knee pain at Y15 in women, independently of radiographic knee OA. When adjusted, the association was significant in bilateral, not unilateral, knee pain, suggesting alternative pathologic mechanisms may exist. The longitudinal effect of BMI on knee pain at Y15 is equally important at any time point, which may assist reducing the population burden of knee pain.
The internal model principle for periodic disturbances with rapidly time‐varying frequencies
Authors: Kinney C. E. , de Callafon R. A.
Published: July 2011

In this paper, we study the limitations of scheduling an internal model to reject disturbances with a time‐varying frequency. Hence, any adaptive method that uses scheduling and frequency estimation is also limited in the same manner. The limitations of scheduling are to investigate by posing and solving the problem of rejecting periodic disturbances from a multichannel system when the frequencies of the periodic disturbances are changing rapidly in time by designing an scheduled controller that satisfies the internal model principle. The periodic disturbances are modeled by a sum of sinusoids and the frequencies of the disturbances are used for scheduling the controller. It is shown that a controller that regulates input additive disturbances may not regulate the same disturbances added to the output of the system. This is in contrast to the classical case where the frequency of the disturbances is constant. Copyright © 2011 John Wiley & Sons, Ltd.
Direct Writing of Polycaprolactone Polymer for Potential Biomedical Engineering Applications
Authors: Rasekh Manoochehr , Ahmad Zeeshan , Day Richard , Wickam Abeni , Edirisinghe Mohan
Published: July 2011

Topography, which in this paper includes the surface features and the features themselves, is a crucial physical cue for cells, influencing cell adhesion, proliferation and differentiation and should be considered when designing biomedical architectures. A new technique using electrohydrodynamic (EH) print‐patterning is described that generates ordered topographies using proven biomaterials and composites. Coupling this method with solvent evaporation techniques, desirable scaffold properties can be achieved. To demonstrate this, various solutions of polycaprolactone (PCL) and its composites (using nano‐hydroxyapatite (nHA)) have been selected to generate topographic and 3D structures. Electrically driven patterning of the polymer is achievable and can be used to deposit fine (<5 µm) ordered structures, according to a predetermined architecture via a computer with control on porosity and bioactivity. The results from this study indicate that this method to deposit bioactive structures with morphology control will offer great potential in biomedical engineering.
Microstructure and Nanoscale Piezoelectric/Ferroelectric Properties in La2Ti2O7 Thin Films Grown on (110)‐Oriented Doped Nb:SrTiO3 Substrates
Authors: Shao Zhenmian , Saitzek Sébastien , Roussel Pascal , Ferri Anthony , Bruyer Émilie , Sayede Adlane , Rguiti Mohamed , Mentré Olivier , Desfeux Rachel
Published: July 2011

(00l)‐Oriented La2Ti2O7 (LTO) thin films with monoclinic perovskite‐layer structure [a = 7.806(2) Å, b = 5.552(3) Å, c = 13.015(5) Å, β = 98.62(2)°] have been grown by a sol–gel route on conducting (110)‐oriented doped Nb:SrTiO3 (STO) substrates. The narrow rocking curves (0.24° width for 004LTO peak) demonstrate the sharp mosaïcity of the films. Using high‐resolution X‐ray diffraction (HR‐XRD), epitaxial relationships between the LTO, and the STO substrate are given. In addition, HR‐XRD evidences the existence of (212)‐oriented crystallites 1.5° disoriented with respect to the plane of the substrate. We confirm, by DFT calculations, that the polarization vector lies in the b‐axis of the LTO cell and consequently, the existence of these (212)‐oriented crystallites enables to explain the origin of the various contrasts observed both on the in‐plane and out‐of‐plane images when collected by piezoresponse force microscopy. Finally, both successful poling experiments performed via the tip of atomic force microscope and the existence of local piezoloops within the domains, unambiguously confirm the ferroelectric state of the films at the nanoscale level. Once again, this study demonstrates that a clear understanding of nanoscale piezoelectric/ferroelectric phenomena in oriented thin films passes through a carefully structural analysis as performed by HR‐XRD.
Organic Resistive Memory Devices: Performance Enhancement, Integration, and Advanced Architectures
Authors: Cho Byungjin , Song Sunghun , Ji Yongsung , Kim Tae‐Wook , Lee Takhee
Published: July 2011

In recent years, organic resistive memory devices in which active organic materials possess at least two stable resistance states have been extensively investigated for their promising memory potential. From the perspective of device fabrication, their advantages include simple device structures, low fabrication costs, and printability. Furthermore, their exceptional electrical performances such as a nondestructive reading process, nonvolatility, a high ON/OFF ratio, and a fast switching speed meet the requirements for viable memory technologies. Full understanding of the underlying physics behind the interesting phenomena is still challenging. However, many studies have provided useful insights into scientific and technical issues surrounding organic resistive memory. This Feature Article begins with a summary on general characteristics of the materials, device structures, and switching mechanisms used in organic resistive devices. Strategies for performance enhancement, integration, and advanced architectures in these devices are also presented, which may open a way toward practically applicable organic memory devices.
Self‐Assembled SERS Substrates with Tunable Surface Plasmon Resonances
Authors: Lee Wonjoo , Lee Seung Yong , Briber Robert M. , Rabin Oded
Published: July 2011

The fabrication of surface‐enhanced Raman spectroscopy (SERS) substrates that are optimized for use with specific laser wavelength–analyte combinations is addressed. In order to achieve large signal enhancement, temporal stability, and reproducibility over large substrate areas at low cost, only self‐assembly and templating processes are employed. The resulting substrates consist of arrays of gold nanospheres with controlled diameter and spacing, properties that dictate the optical response of the structure. Tunability of the extended surface plasmon resonance is observed in the range of 520–1000 nm. It is demonstrated that the enhancement factor is maximized when the surface plasmon resonance is red‐shifted with respect to the SERS instrument laser line. Despite relying on self‐organization, site‐to‐site enhancement factor variations smaller than 10% are obtained.
Bubble behavior in corrugated‐wall bubbling fluidized beds—Experiments and CFD simulations
Authors: Wardag A. N. Khan , Larachi F.
Published: July 2011

A new concept to harness bubble dynamics in bubbling fluidization of Geldart D particles was proposed. Various geometrical declinations of a cold‐prototype corrugated‐wall bubbling fluidized bed were compared at different flow rates (Ug) to conventional flat‐wall fluidized bed using high‐speed digital image analysis. Hydrodynamic studies were carried out to appraise the effect of triangular‐shaped wall corrugation on incipient fluidization, bubble coalescence (size and frequency), bubble rise velocity, and pressure drop. Bubble size and rise velocity in corrugated‐wall beds were appreciably lower, at given Ug/Umb, than in flat‐wall beds with equal flow cross‐sectional areas and initial bed heights. The decrease (increase) in size (frequency) of bubbles during their rise was sustained by their periodic breakups while protruding through the necks between corrugated plates. Euler‐Euler transient full three‐dimensional computational fluid dynamic simulations helped shape an understanding of the impact of corrugation geometry on lowering the minimum bubbling fluidization and improving gas distribution. © 2011 American Institute of Chemical Engineers AIChE J, 2012
Utility of positron emission tomography scans in mantle cell lymphoma
Authors: Hosein Peter J. , Pastorini Vitor H. , Paes Fabio M. , Eber Daryl , Chapman Jennifer R. , Serafini Aldo N. , Alizadeh Ash A. , Lossos Izidore S.
Published: July 2011

Positron emission tomography (PET) scans are widely used in patients with lymphoma but little is known about their utility in mantle cell lymphoma (MCL). MCL patients were included from two prospective trials and one observational study at our institution. A total of 276 PET scans were performed among 52 patients. After a median follow‐up of 37.5 months, the 3‐year event‐free survival (EFS) and overall survival (OS) were 73% (95% confidence interval [CI]: 61–85%) and 92% (95% CI 85–100%), respectively. There were 34 pretreatment PET scans, 26 interim, 28 end‐of‐treatment, 162 surveillance, and 26 scans at relapse or beyond. Pretreatment PETs were positive in 94%. A negative interim or end‐of‐therapy PET scan was not significantly associated with better EFS or OS, but no deaths were observed in patients who had a negative interim or end‐of‐therapy PET. Surveillance PET scans had a high false positive rate (35%) and low positive predictive value (8%). PET scans contributed to an earlier diagnosis of relapse in only two out of the 18 patients (11%) who relapsed. PET scans did not meaningfully contribute to staging or surveillance of MCL patients in this study. There was a trend toward improved survival in patients who had a negative end‐of‐therapy PET scan. Am. J. Hematol., 2011. © 2011 Wiley‐Liss, Inc.
Duplication of the STS region in males is a benign copy‐number variant
Authors: Furrow Aubry , Theisen Aaron , Velsher Lea , Bawle Erawati V. , Sastry Sujatha , Mendelsohn Nancy J. , Jarvis Kristi , Shaffer Lisa G. , Chitayat David
Published: July 2011

Copy‐number variants (CNVs) are a common finding in the human genome, with copy gains occurring at a higher frequency than losses in several databases of genomic variants in normal individuals. Copy gains of the steroid sulfatase (STS) gene have been seen in both males and females. Although deletion of STS in males is known to cause X‐linked ichthyosis, the clinical significance of STS copy gains is less clear, with the duplication reported in individuals with abnormal phenotypes and normal relatives. We identified 72 males submitted to our laboratory for microarray‐based comparative genomic hybridization with duplications in the STS region (chrX:6,465,812–8,093,195). In 40 (56%) patients, maternal blood was available, and the duplication was found to be inherited from the patient's apparently phenotypically normal mother in each of the 40 patients. We also identified three females who inherited a duplication of the STS region from phenotypically normal fathers, and a phenotypically normal uncle who had the same duplication as his nephews. In the remaining cases the inheritance could not be confirmed owing to lack of parental samples available for testing. Of the 72 subjects, 10 (14%) had an additional CNV elsewhere in the genome known to be clinically significant and likely causative of the patient's presenting symptoms. Based on the frequency with which duplications have been identified in clinically normal and abnormal individuals, we suggest a gain of STS in males is a population variant and unlikely to be clinically significant. © 2011 Wiley‐Liss, Inc.
X‐linked mental retardation with alacrima and achalasia—Triple A syndrome or a new syndrome?
Authors: Marom Daphna , Albin Adi , Schwartz Charles , Har‐Zahav Adi , Straussberg Rachel , Bartel Frank , Birk Efrat , Inbar Dov , Basel‐Vanagaite Lina
Published: July 2011

We describe a consanguineous Israeli Arab kindred with five males in two interrelated families with intellectual disabilities, alacrima, achalasia, and mild autonomic dysfunction. Adrenal function is normal. Their phenotype is similar to the phenotype observed in autosomal recessive Triple A syndrome except for the presence of mental retardation in all affected individuals. The pedigree is compatible with either X‐linked or autosomal recessive inheritance. Sequencing of the AAAS gene causing autosomal recessive Triple A syndrome did not reveal mutations. Genotyping of affected family members identified a 16.4 Mb continuous segment of identical alleles shared by the patients between markers rs2748314 and rs5906782 on Xp11.23‐p21, establishing linkage to chromosome X. This study further confirms genetic heterogeneity in Triple A syndrome and points to a clinically different subtype including significant cognitive impairment. © 2011 Wiley‐Liss, Inc.
Facile functionalization of isotactic polypropylene by azide and alkyne groups for click chemistry application
Authors: Zhang Chuanhui , Niu Hui , Dong Jin‐Yong
Published: July 2011

This paper presents two facile methods to achieve functionalization of isotactic polypropylene (i‐PP) by azide and alkyne groups. One method comprises metallocene‐catalyzed isospecific propylene polymerization with dialkylzinc as chain transfer agent to produce iodo‐terminated i‐PP, which can be transformed to azide‐terminated i‐PP. The other utilizes hydroxyl‐grafted i‐PP as a raw material to react with bis(trichloromethyl)carbonate and propargyl amine, generating grafted alkyne groups. Both approaches are effective, controllable and safe. The azide‐terminated and alkyne‐grafted i‐PP are readily applicable to click chemistry for construction of new i‐PP architecture, e.g. long‐chain branched i‐PP. Copyright © 2011 John Wiley & Sons, Ltd.
Preparation of activated carbon from furfural production waste and its application for water pollutants removal and gas separation
Authors: Sun Yong , Wei Jian , Yao Ming‐shun , Yang Gang
Published: July 2011

Activated carbon (ACs) was produced by chemical activation of industrial furfural production waste (FPW) by different chemical activators. The carbon (HP‐AC500) produced from pyrolysis of H3PO4‐FPW at 500 °C is microporous carbon with certain proportion of mesopores whose Brunauer‐Emmett‐Teller (BET) surface area and pore volume could reach 751.8 m2/g and 0.63 mL/g, respectively. The carbon (ZN‐AC600) produced from pyrolysis of ZnCl2‐FPW at 600 °C is essentially microporous carbon whose BET surface area and pore volume could reach 1143 m2/g and 0.61 mL/g, respectively. ZN‐AC600 carbon shows better performance in adsorbing phenol with its maximum monolayer adsorption capacity reaching 166 mg/g, while HP‐AC500 carbon shows its better performance in adsorbing Cr (VI) with maximum monolayer adsorption capacity reaching 27 mg/g. The adsorption model based on Unilan together with Clausius‐Clapeyron equation provides a satisfactory representation for low‐pressure CO2, CH4, N2 adsorption on ZN‐AC600 and HP‐AC500, respectively. Both equilibrium and kinetic results show that the HP‐AC500 carbon has better CO2 separation performance. Copyright © 2011 Curtin University of Technology and John Wiley & Sons, Ltd.
Determination of bubble size distribution in a bubble column reactor using artificial neural network
Authors: Amiri Sahar , Mehrnia Mohammad Reza , Barzegari Davood , Yazdani Aryan
Published: July 2011

In the present study, bubble size distribution (BSD) within a bubble column reactor was modeled using an artificial neural network (ANN). The fluids tested in the bubble column consisted of 11 different oil mixtures, each containing two different oils. Pure water was also tested. BSD was determined for various superficial gas velocities by photographing the state of the fluid. It was found that bubble size as well as distribution depended on parameters, such as gas flow rate, liquid properties, sparger pore diameter and distance from the sparger in the column. The proposed ANN model is based on more than 4500 data points collected for BSD estimation. Through statistical testing, it was found that the model has a correlation coefficient greater than 70% and upon experimental testing was found to better predict BSD than currently used correlations found in the literature. Copyright © 2011 Curtin University of Technology and John Wiley & Sons, Ltd.