Automatic segmentation of thalamus from brain MRI integrating fuzzy clustering and dynamic contours

Thalamus is an important neuro-anatomic structure in the brain. In this paper, an automated method is presented to segment thalamus from magnetic resonance images (MRI). The method is based on a discrete dynamic contour model that consists of vertices and edges connecting adjacent vertices. The model starts from an initial contour and deforms by external and internal forces. Internal forces are calculated from local geometry of the model and external forces are estimated from desired image features such as edges. However, thalamus has low contrast and discontinues edges on MRI, making external force estimation a challenge. The problem is solved using a new algorithm based on fuzzy C-means (FCM) unsupervised clustering, Prewitt edge-finding filter, and morphological operators. In addition, manual definition of the initial contour for the model makes the final segmentation operator-dependent. To eliminate this dependency, new methods are developed for generating the initial contour automatically. The proposed approaches are evaluated and validated by comparing automatic and radiologist's segmentation results and illustrating their agreement.     

Analysis of tilted-coil eccentric borehole antennas in cylindrical multilayered formations for well-logging applications

Well-logging tools employing tilted coil antennas have been proposed to provide directional (azimuth) information and improved estimates of anisotropy when compared to conventional tools that use horizontal coils. In this paper, we analyze the response of logging tools with tilted coil antennas in eccentric boreholes crossing cylindrical multilayered formations (earth formations with invasion zones) by two approaches. The first approach is based on a pseudoanalytic formulation, previously applied for concentric boreholes and extended here to include eccentric boreholes. The second approach is based on three-dimensional (3-D) numerical simulations using the finite-difference time-domain (FDTD) algorithm extended to cylindrical coordinates and incorporating cylindrical perfectly matched layers (PML). The results from the two formulations are compared for different formations, showing very good agreement.     

Study of adsorption of nonionic surfactants at the liquid–solid interface by FTIR/CIR

Fourier transform infrared spectroscopy (FTIR), using the attenuated total reflectance (ATR) method, can be used to characterize the interface of a system. We investigated the adsorption at the liquid–solid interface of nonionic surfactant aqueous solutions with or without a hydrotropic agent. We studied monofunctional diblock copolymers of poly(ethylene oxide‐propylene oxide) (PEO–PPO) as nonionic surfactants and sodium p‐toluenesulfonate (NaPTS) as hydrotropic agent. The samples were analyzed by FTIR technique using the circular internal reflectance (CIR) accessory, which confirmed that the hydrotrope shifts the surfactant from the liquid–solid interface. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1668–1676, 2001     

Structural characterization of TiNxOy/TiO2 single crystalline and nanometric multilayers grown by LP-MOCVD on (110)TiO2

TiO₂/TiN_xO_y superlattices were grown by Low Pressure-Metal-Organic Vapor Phase Epitaxy (LP-MOVPE) technique at deposition temperatures ranking from 650 to 750°C. The growth was performed on top of TiO₂(110) rutile substrates. Intense peaks observed in the X-rays rocking curves and θ-2θ diffraction patterns show the presence of crystalline epilayers. The TiN_xO_y layers were grown in a (200) cubic structure on the (110) quadratic TiO₂ epilayer structure. Transmission electron microscopy confirmed the XRD results and showed the formation of periodic and well structured epilayers.     

Creep properties of eutectic Sn-3.5Ag solder joints reinforced with mechanically incorporated Ni particles

The creep deformation behavior of eutectic Sn-3.5Ag based Ni particle rein forced composite solder joints was investigated. The Ni particle reinforced composite solder was prepared by mechanically dispersing 15 vol.% of Ni particles into eutectic Sn-3.5Ag solder paste. Static-loading creep tests were carried out on solder joint specimens at 25 C, 65 C, and 105 C, representing homologous temperatures ranging from 0.6 to 0.78. A novel-design, miniature creep-testing frame was utilized in this study. Various creep parameters such as the global and localized creep strain, steady-state creep rate, onset of tertiary creep and the activation energy for creep were quantified by mapping the distorted laser ablation pattern imprinted on the solder joint prior to testing. The Ni-reinforced composite solder joint showed improved creep resistance compared to the results previously reported for eutectic Sn-3.5Ag solder, Sn-4.0Ag-0.5Cu solder alloys, and for eutectic Sn-3.5Ag solder reinforced with Cu or Ag particle reinforcements. The activation energy for creep was ∼0.52 eV for Sn-3.5Ag and Sn-4Ag-0.5Cu solder alloys. The activation energies ranged from 0.55–0.64 eV for Cu, Ag, and Ni reinforced composite solder joints, respectively. Most often, creep fracture occurred closer to one side of the solder joint within the solder matrix.     

Conformal PML-FDTD schemes for electromagnetic field simulations: adynamic stability study

We present a study on the dynamic stability of the perfectly matched layer (PML) absorbing boundary condition for finite-difference time-domain (FDTD) simulations of electromagnetic radiation and scattering problems in body-conformal orthogonal grids. This work extends a previous dynamic stability analysis of Cartesian, cylindrical and spherical PMLs to the case of a conformal PML. It is shown that the conformal PML defined over surface terminations with positive local radii of curvature (concave surfaces as viewed from inside the computational domain) is dynamically stable, while the conformal PML defined over surface terminations with a negative local radius (convex surfaces as viewed from inside the computational domain) is dynamically unstable. Numerical results illustrate the analysis     

Study of the myenteric and submucous plexuses after BAC treatment in the intestine of rats.

A morphological and quantitative study in the ileal and colonic myenteric and submucous plexuses of rats after BAC denervation was performed. Four groups were employed: SI--ileum control; CBI--denervated ileum; SC--colon control; and CBC--denervated colon. We used the Myosin-V immunohistochemistry technique to study the myenteric and submucous plexuses. In the submucous plexus of the ileum and colon there was not a significant decrease in the number of neurons/mm2 and of ganglia/mm2. The denervation of the myenteric plexus in the group CBI was 44.7% and in the group CBC, 68.3%. In the myenteric plexus there was also a significant decrease in the number of ganglia/mm2 (13.8% in group CBI and 52.14% in group CBC) and in the number of neurons/ganglion (33.9% in group CBI and 39.6% in group CBC). The morphological analyses showed that there was an alteration in the shape of the ganglia of the ileal and colonic myenteric plexus. The area of the cell bodies had a significant increase both in the myenteric and the submucous plexus in groups CBI and CBC. These data demonstrate that the BAC treatment causes morphologic and quantitative changes in the myenteric plexus and quantitative changes in the cell body area of the submucous plexus.     

Mathematical Modeling of Pottery Production in Different Industrial Furnaces

The traditional process for pottery production was analyzed in this work by developing a fundamental mathematical model that simulates the operation of rustic pottery furnaces as employed by natives of villages in Michoacán, Mexico. The model describes radiative heat transfer and fluid flow promoted by natural convection, phenomena that determine the operation of these furnaces. An advanced radiation model called the “Discrete Ordinates Model” was implemented within a commercial computational fluid dynamics software. Process analysis was performed to determine the effect of the design variables on the quality of the pottery pieces and on energy efficiency. The variables explored were: (a) Geometric aspect ratio between diameter and height of the furnace (D/H) and (b) Refractory thickness (L). The model was validated using experimental temperature measurements from furnaces located in Santa Fe and Capula, Mexico. Good agreement was obtained between experimental and numerically calculated thermal histories. It was found that furnaces with high aspect ratio D/H and with thick refractory bricks promote thermal uniformity and energy savings. In general, any parameter that increases the conductive thermal resistance of the wall furnace isolates better, and helps energy savings. Operating conditions that provide the smallest thermal gradients and lowest energy consumption are given.