Nonlinear Model of Image Noise: An Application on Computed Tomography including Beam Hardening and Image Processing Algorithms

This paper proposes a more inclusive statistical model for predicting image noise in Computed Tomography (CT), associated with scanning factors, considering the effect of beam hardening and image processing filters. It is based on power functions where the levels of the parameters will determine the rate of noise variation with respect to a given scanning factor. It includes the influence of tube potential, tube current, slice thickness, Field of View (FOV), reconstruction methods and post-processing filters. To validate the model, tomographic measurements were made by using a PMMA phantom that simulates paediatric head and adult abdomen, a PET bottle was used to simulate the head of the new-born. The influence of ROI (Region Of Interest) size over nonlinear model parameters was analysed, and high variations of powers of attenuation and FOV were found depending on ROI size. A nonlinear robust regression method was used. The validation was performed graphically by weighted residual analysis. A nonlinear noise model was obtained with an adjusted coefficient of determination for ROI sizes between 10% and 70% of the phantom diameter or FOV. The model confirms the significance of the tube current, slice thickness and beam hardening effect on image. The process of estimation of the parameters of the model by Nonlinear Robust Regression turned out to be optimal.

Performance-Associated Factors of Elderly Patients with a Low Education Level, with Acquired Language Alterations in Tests to Explore Executive Functions

Introduction. Secondary alterations of executive functions occur in brain injuries together with the primary neuropsychological symptoms, irrespective of the location of the damage and the affected neural networks. Such secondary alterations of executive functions in the presence of language alterations, which is the most frequent primary neuropsychological alteration, in addition to exacerbating the linguistic processing deficit, may be associated to multiple factors inherent to the brain injury or the injured patient. Purpose. To describe the secondary neuropsychological alterations of executive functions in elderly patients with low education levels with acquired language disorders and determine general factors of the injury and of the injured patient (etiology, location, time of recovery from the injury, age, education level), associated to such secondary alterations of the Attentional Control System. Patients and Methods. The study was conducted on 68 elderly patients with a low education level with language acquired disorders, of both sexes, ranging between 60 and 80 years of age. The executive functions explored included cognitive flexibility, impulsivity control and inhibition of irrelevant automatisms, with the Trail Making Test, the Porteus Maze Test and series of loops. Statistical processing involved a Distribution of Frequencies and Multiple Ordinal Regression. Results and Conclusions. The statistical analysis found secondary neuropsychological alterations of the executive functioning in the elderly patients with language disorders of the study that are associated to the location and the time of recovery from the injury and are irrespective of age, education level and etiology of the injury.

Modeling Integrated Coastal Flood Hazard in Hurricane Season

The manuscript proposed a procedure designed to determine the hazard of total coastal flooding during the impact of hurricanes, which uses in its formulation the combination of river flooding and that caused by marine upwelling, which is multiplied by a density factor of the water that finds an explanation for the effect is shielding and rising of the water level when the currents of both floods collide in the coastal zone. The application of the procedure experimentally in the coastal sector Sevilla, of the municipality Guama province Santiago de Cuba, resulting in the confirmation of areas previously modeled and estimated coastal flooding in the wake of extreme weather events in the study area;in addition to other new areas that confirm the actual visual and instrumental observations not included in previous studies.

Differential IFN-Gamma (IFN-γ), Interleukin 10 (IL-10) and Cardiac Troponin I (cTnI) Responses in Natural Bovine Trypanosomosis in Nigeria

Trypanosomosis is major drawback to profitable livestock production in sub-Sahara African, including Nigeria. Knowledge of the cytokines production in the phase of natural infection may help to better diagnose, treat and prevent bovine trypanosomosis. The purpose of the this study was to determine the levels of interferon-gamma (IFN-γ), interleukin-10 (IL-10) and cardiac troponin–I (cTnI) in the sera of cattle naturally infected with T. brucei, T. congolense and T. vivax and correlate these levels with parasitaemia and PCV of the infected animals. Five milliliter of blood samples were collected via the jugular vein from 411 randomly selected cattle into EDTA and non-citrated bottle. PCV was determined manually using HCT. Trypansomes were detected and characterized by microscopy and PCR, respectively. Serum levels of IFN-γ, IL-10 and cTnI were determined using commercial ELISA kit. Data were summarized using descriptive statistic and significance of differences determined by ANOVA. Of the 62 samples positive for trypanosomes by microscopy, 50 samples were confirmed to species level by PCR. The sera levels of IFN-γ, IL-10 and cTnI of infected cattle were higher than non-infected cattle. The differences were not significant (p γ, IL-10 and cTnI in cattle with natural trypanosomosis. Further investigation is required to understand the specific effect of trypanosomes on myocardiac integrity and interaction between the two cytokines in natural trypanosomosis in cattle.

Hlder Norm Estimate for a Hilbert Transform in Hermitean Clifford Analysis

A Hilbert transform for H61der continuous circulant （2 × 2） matrix functions, on the d- summable （or fractal） boundary F of a Jordan domain Ω in R2n, has recently been introduced within the framework of Hermitean Clifford analysis. The main goal of the present paper is to estimate the HSlder norm of this Hermitean Hilbert transform. The expression for the upper bound of this norm is given in terms of the HSlder exponents, the diameter of F and a specific d-sum （d 〉 d） of the Whitney decomposition of Ω. The result is shown to include the case of a more standard Hilbert transform for domains with left Ahlfors-David regular boundary.

Design of active orthoses for a robotic gait rehabilitation system

An active orthosis （AO） is a robotic device that assists both human gait and rehabilitation therapy. This work proposes portable AOs, one for the knee joint and another for the ankle joint. Both AOs will be used to complete a robotic system that improves gait rehabilitation. The requirements for actuator selection, the biomechanical considerations during the AO design, the finite element method, and a control approach based on electroencepha-lographic and surface electromyographic signals are reviewed. This work contributes to the design of AOs for users with foot drop and knee flexion impairment. However, the potential of the proposed AOs to be part of a robotic gait rehabilitation system that improves the quality of life of stroke survivors requires further investigation.

Measure of Segments which Intersect a Convex Body from Rotational Formulae

Classical problems in integral geometry and geometric probability involve the kinematic measure of congruent segments of fixed length within a convex body in R3. We give this measure from rotational formulae; that is, from isotropic plane sections through a fixed point. From this result we also obtain a new rotational formula for the volume of a convex body; which is proved to be equivalent to the wedge formula for the volume.

Precipitation Kinetics on a Nb-V Microalloyed Steel

The precipitation kinetics in a low carbon high strength low alloy (HSLA) steel,microalloyed with V+Nb has been studied by using the stress relaxation method.This technique was carried out in a dynamic dilatometer and allows to determine the onset and finishing precipitation times in hot deformed austenite.The evolution of the precipitates was also observed using field emission scanning electron microscopy (FESEM) on samples quenched at different times at given temperatures.Discussion is completed with the predictions by the thermodynamic software FactSage to identify stable precipitate phases under equilibrium conditions.Results confirm the feasibility of the stress relaxation technique as an efficient method for investigating precipitation kinetics.

Strain Influence on the Precipitation Kinetic Nb-V Microalloyed HSLA Steel

The strain induced effect on the precipitation kinetics of a high strength low alloy (HSLA) steel microalloyed with Nb-V was investigated.The stress relaxation method was employed to determine the dependence of the precipitation-time-temperature curves (PTT) on previous strain.Relaxation tests were performed over a temperature range of 850 to 1150 oC at a constant strain rate of 0.1 s-1 at three deformation levels,namely 5,15 and 25 pct.Field emission scanning electron microscopy (FESEM) was used to study the progress of precipitation on samples obtained by interrupted relaxation test at different times.Results display the acceleration kinetics at increasing strain.Theoretical models are discussed and compared with the present experimental results.