3,018 research outputs found

    Analysis and Design of Infrared Fiber Bundles for Large Field-of-View Thermal Imaging

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    During the DARPA SCENICC program, J. Ford, et al., demonstrated that CFBs provide a compelling route to compact, wide angle imagers. Monocentric lenses readily provide diffraction-limited images over wide field but onto a hemispherically curved image surface. They demonstrated visible CFBs can be tapered, cut and polished to relay curved images to flat sensors. We have shown that this provides a volumetric imaging efficiency a hundredfold larger than bulk optics can produce; a hundred times the resolution in the same volume or a hundred times less volume for the same resolution. Ford\u27s work leveraged commercial fiber bundles available for the visible spectrum based on silica. We have developed hybrid fiber bundles using step-index confinement between chalcogenide glass cores and polymer cladding with high index-contrast. The high contrast is necessary to provide tight confinement to the high-index As-Se core with minimal crosstalk between closely spaced cores. Tight confinement also minimizes absorption losses in the PEI polymer cladding. The high contrast of this system also provides a large NA to optimize coupling into the CFB from fast lenses. We introduce disorder into the core radius as a mechanism to further decouple adjacent cores, reduce crosstalk and increase fill-factor. We present coupled-mode theory, modal crosstalk superposition, and finite-element modelling to quantify coupling losses and crosstalk as a function of geometry and disorder. We fabricated preforms, drew small fiber bundles and characterized optical properties of the bundles to aid scale-up to megapixel MWIR CFBs

    Optical Characterization of Liquids: Refractive Index and Raman Gain Coefficient Measurements

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    Novel technologies capable of generating wavelengths not accessible with typical laser gain media have been among the primary drivers of the field of nonlinear optics. Here, we are interested in the linear and nonlinear properties of liquids beyond the visible spectrum, motivated in part by their use as core materials in optical fibers. Given their dispersion, nonlinearities, transparency, and ability to be mixed, liquids show potential for exploiting in-fiber nonlinear phenomena for developing the new generation of low cost, size, weight, and power wavelength-agile fiber-laser sources. For the design, modeling, and experimental realization of these liquid-core fiber laser sources, proper knowledge of dispersion and Raman gain coefficients is necessary. However, the data for the liquids in the near-IR spectrum are sparse, with most reported values being in the visible and only for commonly used solvents. In this thesis, we report a Rayleigh interferometry-based refractometer to characterize the refractive index of 26 solvents relative to standard materials at seven different wavelengths (543.5, 632.8, 780, 973, 1064, 1550, and 1970 nm) at a temperature of ~ 21.3±0.6 °C. The corresponding Sellmeier equations fitted to our data for each liquid are given and compared with previously published literature; percent transmittance data for each liquid are also provided. Furthermore, we use a well-known technique for obtaining the relative total differential Raman cross-section of eight selected solvents at 532 nm. By measuring and analyzing the solvents\u27 spontaneous Raman emission, we obtain their depolarization ratios, linewidth, and calculate their Raman gain coefficients. With knowledge of the electronic resonance and frequency dependence of the total differential cross-section, extrapolations were used to provide values for the total differential cross-section and gain coefficient at 1064 nm

    Molecular Mechanism of Cyclodextrin Mediated Cholesterol Extraction

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    The depletion of cholesterol from membranes, mediated by β-cyclodextrin (β-CD) is well known and documented, but the molecular details of this process are largely unknown. Using molecular dynamics simulations, we have been able to study the CD mediated extraction of cholesterol from model membranes, in particular from a pure cholesterol monolayer, at atomic resolution. Our results show that efficient cholesterol extraction depends on the structural distribution of the CDs on the surface of the monolayer. With a suitably oriented dimer, cholesterol is extracted spontaneously on a nanosecond time scale. Additional free energy calculations reveal that the CDs have a strong affinity to bind to the membrane surface, and, by doing so, destabilize the local packing of cholesterol molecules making their extraction favorable. Our results have implications for the interpretation of experimental measurements, and may help in the rational design of efficient CD based nano-carriers

    Analyzing the Effects of Body Mass Index in Total Hip Arthroplasty Cases. Does it Influence Patient Characteristics, Operative Planning, and Postoperative Outcomes?

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    Background: Total hip arthroplasty (THA) is one of the most performed orthopaedic procedures commonly used for the treatment of osteoarthritis (OA). There are several underlying factors that lead to the formation of this condition. Not only is obesity one of the main contributors, but it is also a modifiable risk factor and one of the leading causes of end-stage arthrosis of the hip. Though there have been advancements in agricultural and health technologies, rates of obesity continue to rise causing similar increases in the demands for hip replacement surgeries. Therefore, we sought to investigate the effects of BMI on THA procedures and determine if it plays any influential role in patient characteristics, operative planning, and postoperative outcomes. Methods: A prospectively collected database from a single institution was queried from January 2018 to December 2021, to identify 66 THA patients (mean age 69.5) included in this study. Patient’s BMI were recorded preoperatively and separated into five classes in accordance with the World Health Organization classification of Normal (18.5-24.9), Pre-Obesity (25.0-29.9), Obesity Class I (30.0-34.9), Obesity Class II (35.0-39.9), and Obesity Class III (BMI ≥ 40). Patient attributes, operative characteristics, and postoperative outcomes were then stratified and grouped into the different BMI classes. All patients had radiograph imaging obtained preoperatively and at a minimum 9-month interval to observe for the presence of any radiolucent lines which would be plotted using the hip regions set forth by De Lee and Charnley. Results: The mean BMI of our patient population was 30.5 which overall characterizes it as Obesity Class I. However, the classification that contained the most of our population was Pre-Obesity (n = 26, 39.4%). There were no males in our entire population that had a BMI considered normal, but 13 females did fall into this classification. There was a significant number of patients who underwent a direct anterior approach within the Pre-Obesity classification than those who underwent a posterolateral approach (21 vs 5 patients, P value = 0.047). However, for subjects meeting Obesity Class II and Class III criteria, a significant number of posterolateral approaches were performed than the direct anterior approach. In analyzing the radiographs, only 2 patients were discovered to have radiolucent lines, but no related symptoms or physical complications were reported. Conclusion: Our investigation demonstrates that having a higher BMI only significantly affects the surgical approach to THA but can conclude that it is an excellent surgical option for the treatment of OA in obese patients

    Dental Treatment under General Anesthesia in Healthy and Medically Compromised/Developmentally Disabled Children: A Comparative Study

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    Aim: To compare the type, number of procedures and working time of dental treatment provided under dental general anesthesia (DGA) in healthy and medically compromised/developmentally disabled children (MCDD children). Design: This cross-sectional prospective study involved 80 children divided into two groups of 40 children each. Group 1 consisted of healthy and Group 2 consisted of MCDD children. Results: Healthy children needed more working time than MCDD children, the means being 161±7.9 and 84±5.7 minutes, respectively (P= 0.0001). Operative dentistry and endodontic treatments showed a significant statistical difference (P= 0.0001). The means of procedures were 17±5.0 for healthy children and 11±4.8 for MCDD children (P= 0.0001). Conclusions: Healthy children needed more extensive dental treatment than MCDD children under DGA. The information from this sample of Mexican children could be used as reference for determining trends both within a facility as well as in comparing facilities in cross-population studies

    SISTEMAS DE PRODUCCIÓN DE ACUACULTURA CON RECIRCULACIÓN DE AGUA PARA LA REGIÓN NORTE, NORESTE Y NOROESTE DE MÉXICO

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    Aquaculture is expanding and developing in practically all the regions of the world. The demand of the world-wide population by aquatic products is increasing, whereas the production from capture of fisheries has been being reduced, reaching many of them their maximum productive potential. As result of, sustaining fish supplies from capture fisheries it will not be possible to meet the growing global demand for aquatic food. Therefore, the aquaculture seems to have the potential to make a significant contribution to the production of these foods, in order to meet the growing population demand. Nevertheless, in order to accomplish it, the producer faces critical challenges. The development of these activities intensifies substantially, and requires to be diversified, producing new species and creating new systems and practices of production. The production systems of aquatic animals, particularly those based on technologies of water recirculation, appears to be an excellent alternative for producing, in regions of the North of Mexico, in where the water is scarce.Aquaculture, word wide population, aquatic food., Agribusiness,

    Avifauna en un area perturbada del bosque andino en el parque nacional natural Farallones de Cali, corregimiento de Pance, Valle del Cauca (Colombia)

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    El presente conjunto de datos en el formato de archivo Darwin Core incluye información del monitoreo de la avifauna en un área perturbada del Parque Nacional Natural Farallones de Cali. Con el objetivo de caracterizar y determinar la composición y estructura de la avifauna, se llevaron a cabo censos visuales desde agosto 2008 hasta julio 2009 en las localidades de El Topacio y El Pato en recorridos de 2 km de longitud, a elevaciones entre 1550 y 1800 m s.n.m. En total se hicieron 2363 registros de 157 especies de aves, pertenecientes a 41 familias y 19 órdenes. Se observaron 12 especies nuevas para el área, 10 de las cuales son aves propias de áreas abiertas. Nueve especies que habían sido registradas en El Topacio en 1978, no lo fueron en el presente estudio y en consecuencia se consideran extintas y vulnerables localmente, lo cual ilustra y ratifica cómo el reemplazo de los hábitats naturales por potreros, la fragmentación y el efecto de borde afectan negativamente las comunidades de aves en áreas protegidas.This dataset in Darwin Core Archive format includes monitoring information about bird life in a disturbed area of the Farallones de Cali National Natural Park. Aiming to characterize and determine the composition and structure of bird life, visual censuses were carried out from August 2008 to July 2009 at both the El Pato and the El Topacio localities along line census of 2 km and from elevations between1550 to 1800 m a.s.l. A total of 2363 records were obtained of 157 species of 41 families and 19 orders. Twelve were new records for the area, 10 of which are common in open areas. Nine species previously recorded in 1978 at El Topacio were absent and considered locally extinct and vulnerable. This illustrates how the replacement of natural habitats with pasturelands, as well as fragmentation and border effect affect negatively bird communities in protected areas.Fil: Bermudez Vera, Julio Cesar . Universidad del Valle. Departamento de Biología; ColombiaFil: Duque Lopez, Juan Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Centro de Investigación Esquel de Montaña y Estepa Patagónicas; ArgentinaFil: Sanchez Martinez, Manuel A. . Universidad del Valle. Departamento de Biología; ColombiaFil: Tenorio, Elkin . Calima - Fundación para la Investigación de la Biodiversidad y Conservación en el Trópico; Colombi

    Outcomes Following Total Hip Arthroplasty for Hip Dysplasia in Older Adults. Are They Comparable to Those with Osteoarthritis?

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    Background: Total hip arthroplasty (THA) for the treatment of hip dysplasia, which disproportionately impacts the younger population, has been shown to be an effective intervention to restore functionality and improve quality of life. However, it is unclear whether these outcomes can be just as beneficial in treating hip dysplasia when it presents in older patients. Therefore, we sought to investigate and compare the pre-and postoperative outcomes of THA for hip dysplasia in older adults to those with end-stage osteoarthritis (OA). Methods: A prospectively collected database from a single institution was queried from September 1st, 2016 to October 31st, 2021 to identify 323 unilateral THA patients age 50 years or older and separated into 2 groups given a primary diagnosis of hip dysplasia (n = 90 patients) or osteoarthritis (n = 233 patients). Preoperative and minimum 1-year postoperative outcomes were then compared using the Hip Outcome Score (HOS), Hip Disability and Osteoarthritis Outcome Score (HOOS), University of California-Los Angeles (UCLA) activity score, Pain Catastrophizing Score (PCS), and the Depression Anxiety Stress Scale (DASS). Results: The outcomes between the groups showed no significant differences in their pre-and postoperative HOOS (P = 0.22 and P = 0.63 respectively), DASS Anxiety (P = 0.81 and P = 0.29 respectively), and the DASS Stress Score (P = 0.17 and P = 0.28 respectively). Patients with hip dysplasia reported significantly better preoperative (10.1 vs 12.9, P P = 0.01) DASS Depression Scores but scored significantly lower in the pre-operative HOS (35.4 vs 42.2, P P = 0.02), but no significant difference was seen postoperatively (4.6 vs 5.0, P = 0.11). The PCS noted no significant differences preoperatively (23.2 vs 21.0, P = 0.12). However, the hip dysplasia group has significantly better postoperative scores (6.6 vs 10.0, P = 0.02). Conclusion: Our investigation demonstrates THA as an excellent surgical option for treating hip dysplasia when presenting in older adults and can yield comparable outcomes as those noted in THA performed for OA in older adults
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