Endoscopic low-coherence topography measurement for upper airways and hollow samples.

To evaluate the severity of airway pathologies, quantitative dimensioning of airways is of utmost importance. Endoscopic vision gives a projective image and thus no true scaling information can be directly deduced from it. In this article, an approach based on an interferometric setup, a low-coherence laser source and a standard rigid endoscope is presented, and applied to hollow samples measurements. More generally, the use of the low-coherence interferometric setup detailed here could be extended to any other endoscopy-related field of interest, e.g., gastroscopy, arthroscopy and other medical or industrial applications where tri-dimensional topology is required. The setup design with a multiple fibers illumination system is presented. Demonstration of the method ability to operate on biological samples is assessed through measurements on ex vivo pig bronchi.

Evaluation of Reducibility of Trunk Asymmetry in Lateral Bending

The value of the lateral bending test is important in the assessment of spinal curve mobility and prediction of surgical outcome in the treatment of adolescent idiopathic scoliosis (AIS). However, radiographic bending tests are unable to assess the reducibility of trunk asymmetry. This study aims to exploit surface topography measurement in order to evaluate the changes in shape of the trunk (a) between bending and neutral standing positions, and (b) between standing pre- and post-operative visits, in a cohort of adolescents with AIS having undergone surgical correction; and to correlate the differences measured in cases (a) and (b). Our cohort includes 13 patients with right thoracic AIS. Each patient had their 3D trunk surface digitized with a multi-head InSpeck system in standing posture (at the pre-op and post-op visits) and in maximum voluntary right and left bending (at the pre-op visit). We developed a novel trunk shape analysis method which produces a set of inclined trunk cross-sections allowing comparison between different postures. Two asymmetry indices, trunk rotation (TR) and back surface rotation (BSR), were computed in all cases and a statistical analysis was performed. Our correlation study (Pearson test) showed fair correlations in most cases between the changes in side-bending and those post-surgery, with the strongest relationship (p-value < 0.01) when combining the TR measurements from both bendings. These results provide evidence that the bending test can be used to assess trunk asymmetry reducibility. The proposed approach could provide a non-invasive trunk asymmetry reducibility test for routine clinical use in AIS surgery planning.

Patient-specific finite-element simulation of the human cornea: A clinical validation study on cataract surgery

The planning of refractive surgical interventions is a challenging task. Numerical modeling has been proposed as a solution to support surgical intervention and predict the visual acuity, but validation on patient specific intervention is missing. The purpose of this study was to validate the numerical predictions of the post-operative corneal topography induced by the incisions required for cataract surgery. The corneal topography of 13 patients was assessed preoperatively and postoperatively (1-day and 30-day follow-up) with a Pentacam tomography device. The preoperatively acquired geometric corneal topography – anterior, posterior and pachymetry data – was used to build patient-specific finite element models. For each patient, the effects of the cataract incisions were simulated numerically and the resulting corneal surfaces were compared to the clinical postoperative measurements at one day and at 30-days follow up. Results showed that the model was able to reproduce experimental measurements with an error on the surgically induced sphere of 0.38D one day postoperatively and 0.19D 30 days postoperatively. The standard deviation of the surgically induced cylinder was 0.54D at the first postoperative day and 0.38D 30 days postoperatively. The prediction errors in surface elevation and curvature were below the topography measurement device accuracy of ±5μm and ±0.25D after the 30-day follow-up. The results showed that finite element simulations of corneal biomechanics are able to predict post cataract surgery within topography measurement device accuracy. We can conclude that the numerical simulation can become a valuable tool to plan corneal incisions in cataract surgery and other ophthalmosurgical procedures in order to optimize patients' refractive outcome and visual function.

Validity of a Quantitative Clinical Measurement Tool of Trunk Posture in Idiopathic Scoliosis

STUDY DESIGN: Concurrent validity between postural indices obtained from digital photographs (two-dimensional [2D]), surface topography imaging (three-dimensional [3D]), and radiographs. OBJECTIVE: To assess the validity of a quantitative clinical postural assessment tool of the trunk based on photographs (2D) as compared to a surface topography system (3D) as well as indices calculated from radiographs. SUMMARY OF BACKGROUND DATA: To monitor progression of scoliosis or change in posture over time in young persons with idiopathic scoliosis (IS), noninvasive and nonionizing methods are recommended. In a clinical setting, posture can be quite easily assessed by calculating key postural indices from photographs. METHODS: Quantitative postural indices of 70 subjects aged 10 to 20 years old with IS (Cobb angle, 15 degrees -60 degrees) were measured from photographs and from 3D trunk surface images taken in the standing position. Shoulder, scapula, trunk list, pelvis, scoliosis, and waist angles indices were calculated with specially designed software. Frontal and sagittal Cobb angles and trunk list were also calculated on radiographs. The Pearson correlation coefficients (r) was used to estimate concurrent validity of the 2D clinical postural tool of the trunk with indices extracted from the 3D system and with those obtained from radiographs. RESULTS: The correlation between 2D and 3D indices was good to excellent for shoulder, pelvis, trunk list, and thoracic scoliosis (0.81>r<0.97; P<0.01) but fair to moderate for thoracic kyphosis, lumbar lordosis, and thoracolumbar or lumbar scoliosis (0.30>r<0.56; P<0.05). The correlation between 2D and radiograph spinal indices was fair to good (-0.33 to -0.80 with Cobb angles and 0.76 for trunk list; P<0.05). CONCLUSION: This tool will facilitate clinical practice by monitoring trunk posture among persons with IS. Further, it may contribute to a reduction in the use of radiographs to monitor scoliosis progression.

Soil CO2 emission of sugarcane fields as affected by topography

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

2-D ZO CRS stack by considering an acquisition line with smooth topography

Os dados sísmicos terrestres são afetados pela existência de irregularidades na superfície de medição, e.g. a topografia. Neste sentido, para obter uma imagem sísmica de alta resolução, faz-se necessário corrigir estas irregularidades usando técnicas de processamento sísmico, e.g. correições estáticas residuais e de campo. O método de empilhamento Superfície de Reflexão Comum, CRS ("Common-Reflection-Surface", em inglês) é uma nova técnica de processamento para simular seções sísmicas com afastamento-nulo, ZO ("Zero-Offset", em inglês) a partir de dados sísmicos de cobertura múltipla. Este método baseia-se na aproximação hiperbólica de tempos de trânsito paraxiais de segunda ordem referido ao raio (central) normal. O operador de empilhamento CRS para uma superfície de medição planar depende de três parâmetros, denominados o ângulo de emergência do raio normal, a curvatura da onda Ponto de Incidência Normal, NIP ("Normal Incidence Point", em inglês) e a curvatura da onda Normal, N. Neste artigo o método de empilhamento CRS ZO 2-D é modificado com a finalidade de considerar uma superfície de medição com topografia suave também dependente desses parâmetros. Com este novo formalismo CRS, obtemos uma seção sísmica ZO de alta resolução, sem aplicar as correições estáticas, onde em cada ponto desta seção são estimados os três parâmetros relevantes do processo de empilhamento CRS.

Uncalibrated temperature measurement during R/V Maria S. Merian cruise MSM21/1b

GEOMAR's autonomous underwater vehicle (AUV Abyss REMUS 6000) was deployed within the framework of a multi-platform experiment in June 2012 with R/V Maria S. Merian cruise MSM21/1b at about 180 km downstream of Denmark Strait. The scientific payload included a pumped Seabird 49 FastCAT CTD system, a paroscientific pressure sensor, and shear and temperature microstructure profiler from Rockland Scientific Inc.. In total, six of eight AUV dives were carried out successfully. Aborts on three dives were caused by strong counter currents the AUV experienced in the Denmark Strait Overflow plume, which made the AUV fail to reach its waypoints on schedule. During all missions the AUV was programmed to dive at constant depth levels along? straight legs approximately parallel to chosen isobaths with a constant speed of 1.6 m s-1 through the water.

Quantitative measurement using scanning thermal microscopy

This thesis reports on the development of quantitative measurement using micromachined scanning thermal microscopy (SThM) probes. These thermal probes employ a resistive element at their end, which can be used in passive or active modes. With the help of a review of SThM, the current issues and potentials associated with this technique are revealed. As a consequence of this understanding, several experimental and theoretical methods are discussed, which expand our understanding of these probes. The whole thesis can be summarized into three parts, one focusing on the thermal probe, one on probe-sample thermal interactions, and the third on heat transfer within the sample. In the first part, a series of experiments are demonstrated, aimed at characterizing the probe in its electrical and thermal properties, benefiting advanced probe design, and laying a fundamental base for quantifying the temperature of the probe. The second part focuses on two artifacts observed during the thermal scans – one induced by topography and the other by air conduction. Correspondingly, two devices, probing these artifacts, are developed. A topography-free sample, utilizing a pattern transfer technique, minimises topography-related artifacts that limited the reliability of SThM data; a controlled temperature ‘Johnson noise device’, with multiple-heater design, offers a uniform, accurate, temperature distribution. Analyzing results of scan from these samples provides data for studying the thermal interactions within the probe and the tip-sample interface. In the final part, the observation is presented that quantification of measurements depends not only on an accurate measurement tool, but also on a deep understanding of the heat transfer within the sample resulting from the nanoscopic contact. It is believed that work in this thesis contributes to SThM gaining wider application in the scientific community.

Measurement Of Longitudinal Spin Asymmetries For Weak Boson Production In Polarized Proton-proton Collisions At Rhic.

We report measurements of single- and double-spin asymmetries for W^{±} and Z/γ^{*} boson production in longitudinally polarized p+p collisions at sqrt[s]=510  GeV by the STAR experiment at RHIC. The asymmetries for W^{±} were measured as a function of the decay lepton pseudorapidity, which provides a theoretically clean probe of the proton's polarized quark distributions at the scale of the W mass. The results are compared to theoretical predictions, constrained by polarized deep inelastic scattering measurements, and show a preference for a sizable, positive up antiquark polarization in the range 0.05

Corrosion Kinetics And Topography Analysis Of Ti-6al-4v Alloy Subjected To Different Mouthwash Solutions.

This study evaluated the corrosion kinetics and surface topography of Ti-6Al-4V alloy exposed to mouthwash solutions (0.12% chlorhexidine digluconate, 0.053% cetylpyridinium chloride and 3% hydrogen peroxide) compared to artificial saliva (pH6.5) (control). Twenty Ti-6Al-4V alloy disks were used and divided into 4 groups (n=5). For the electrochemical assay, standard tests as open circuit potential and electrochemical impedance spectroscopy (EIS) were applied at baseline, 7 and 14days after immersion in the solutions. Scanning electron microscopy, atomic force microscopy and profilometry (average roughness - Ra) were used for surface characterization. Total weight loss of disks was calculated. Data were analyzed by ANOVA and Bonferroni's test (α=0.05). Hydrogen peroxide generated the lowest polarization resistance (Rp) values for all periods (P<0.05). For the capacitance (Cdl), similar results were observed among groups at baseline (P=0.098). For the 7 and 14-day periods, hydrogen peroxide promoted the highest Cdl values (P<0.0001). Hydrogen peroxide promoted expressive superficial changes and greater Ra values than the others (P<0.0001). It could be concluded that solutions containing cetylpyridinium chloride and chlorhexidine digluconate might be the mouthwashes of choice during the post-operatory period of dental implants. However, hydrogen peroxide is counter-indicated in these situations. Further studies evaluating the dynamics of these solutions (tribocorrosion) and immersing the disks in daily cycles (two or three times a day) to mimic a clinical situation closest to the application of mouthwashes in the oral cavity are warranted to prove our results.

Measurement Of The Hydrodynamic Radius Of Quantum Dots By Fluorescence Correlation Spectroscopy Excluding Blinking.

One of the most important properties of quantum dots (QDs) is their size. Their size will determine optical properties and in a colloidal medium their range of interaction. The most common techniques used to measure QD size are transmission electron microscopy (TEM) and X-ray diffraction. However, these techniques demand the sample to be dried and under a vacuum. This way any hydrodynamic information is excluded and the preparation process may alter even the size of the QDs. Fluorescence correlation spectroscopy (FCS) is an optical technique with single molecule sensitivity capable of extracting the hydrodynamic radius (HR) of the QDs. The main drawback of FCS is the blinking phenomenon that alters the correlation function implicating in a QD apparent size smaller than it really is. In this work, we developed a method to exclude blinking of the FCS and measured the HR of colloidal QDs. We compared our results with TEM images, and the HR obtained by FCS is higher than the radius measured by TEM. We attribute this difference to the cap layer of the QD that cannot be seen in the TEM images.

[construction Of Measurement Instruments In The Area Of Health].

Measurement instruments are an integral part of clinical practice, health evaluation and research. These instruments are only useful and able to present scientifically robust results when they are developed properly and have appropriate psychometric properties. Despite the significant increase of rating scales, the literature suggests that many of them have not been adequately developed and validated. The scope of this study was to conduct a narrative review on the process of developing new measurement instruments and to present some tools which can be used in some stages of the development process. The steps described were: I-The establishment of a conceptual framework, and the definition of the objectives of the instrument and the population involved; II-Development of the items and of the response scales; III-Selection and organization of the items and structuring of the instrument; IV-Content validity, V-Pre-test. This study also included a brief discussion on the evaluation of the psychometric properties due to their importance for the instruments to be accepted and acknowledged in both scientific and clinical environments.

Operant measurement of auditory threshold in prelingually deaf users of cochlear implants: II

Two experiments evaluated an operant procedure for establishing stimulus control using auditory and electrical stimuli as a baseline for measuring the electrical current threshold of electrodes implanted in the cochlea. Twenty-one prelingually deaf children, users of cochlear implants, learned a Go/No Go auditory discrimination task (i.e., pressing a button in the presence of the stimulus but not in its absence). When the simple discrimination baseline became stable, the electrical current was manipulated in descending and ascending series according to an adapted staircase method. Thresholds were determined for three electrodes, one in each location in the cochlea (basal, medial, and apical). Stimulus control was maintained within a certain range of decreasing electrical current but was eventually disrupted. Increasing the current recovered stimulus control, thus allowing the determination of a range of electrical currents that could be defined as the threshold. The present study demonstrated the feasibility of the operant procedure combined with a psychophysical method for threshold assessment, thus contributing to the routine fitting and maintenance of cochlear implants within the limitations of a hospital setting.

Resultados preliminares de um sistema de topografia de grande-ângulo usando videoceratógrafo com discos de Plácido

OBJETIVO: Desenvolver a instrumentação e o "software" para topografia de córnea de grande-ângulo usando o tradicional disco de Plácido. O objetivo é permitir o mapeamento de uma região maior da córnea para topógrafos de córnea que usem a técnica de Plácido, fazendo-se uma adaptação simples na mira. MÉTODOS: Utilizando o tradicional disco de Plácido de um topógrafo de córnea tradicional, 9 LEDs (Light Emitting Diodes) foram adaptados no anteparo cônico para que o paciente voluntário pudesse fixar o olhar em diferentes direções. Para cada direção imagens de Plácido foram digitalizadas e processadas para formar, por meio de algoritmo envolvendo elementos sofisticados de computação gráfica, um mapa tridimensional completo da córnea toda. RESULTADOS: Resultados apresentados neste trabalho mostram que uma região de até 100% maior pode ser mapeada usando esta técnica, permitindo que o clínico mapeie até próximo ao limbo da córnea. São apresentados aqui os resultados para uma superfície esférica de calibração e também para uma córnea in vivo com alto grau de astigmatismo, mostrando a curvatura e elevação. CONCLUSÃO: Acredita-se que esta nova técnica pode propiciar a melhoria de alguns processos, como por exemplo: adaptação de lentes de contato, algoritmos para ablações costumizadas para hipermetropia, entre outros.