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1.
Front Plant Sci ; 14: 1253640, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37780496

RESUMEN

Allotopic expression is the term given for the deliberate relocation of gene function from an organellar genome to the nuclear genome. We hypothesized that the allotopic expression of an essential mitochondrial gene using a promoter that expressed efficiently in all cell types except those responsible for male reproduction would yield a cytoplasmic male sterility (CMS) phenotype once the endogenous mitochondrial gene was inactivated via genome editing. To test this, we repurposed the mitochondrially encoded atp1 gene of tobacco to function in the nucleus under the transcriptional control of a CaMV 35S promoter (construct 35S:nATP1), a promoter that has been shown to be minimally expressed in early stages of anther development. The endogenous atp1 gene was eliminated (Δatp1) from 35S:nATP1 tobacco plants using custom-designed meganucleases directed to the mitochondria. Vegetative growth of most 35S:nATP1/Δatp1 plants appeared normal, but upon flowering produced malformed anthers that failed to shed pollen. When 35S:nATP1/Δatp1 plants were cross-pollinated, ovary/capsule development appeared normal, but the vast majority of the resultant seeds were small, largely hollow and failed to germinate, a phenotype akin to the seedless trait known as stenospermocarpy. Characterization of the mitochondrial genomes from three independent Δatp1 events suggested that spontaneous recombination over regions of microhomology and substoichiometric shifting were the mechanisms responsible for atp1 elimination and genome rearrangement in response to exposure to the atp1-targeting meganucleases. Should the results reported here in tobacco prove to be translatable to other crop species, then multiple applications of allotopic expression of an essential mitochondrial gene followed by its elimination through genome editing can be envisaged. Depending on the promoter(s) used to drive the allotopic gene, this technology may have potential application in the areas of: (1) CMS trait development for use in hybrid seed production; (2) seedless fruit production; and (3) transgene containment.

2.
Sensors (Basel) ; 23(18)2023 Sep 16.
Artículo en Inglés | MEDLINE | ID: mdl-37765987

RESUMEN

There have been sustained efforts toward using naturalistic methods in developmental science to measure infant behaviors in the real world from an egocentric perspective because statistical regularities in the environment can shape and be shaped by the developing infant. However, there is no user-friendly and unobtrusive technology to densely and reliably sample life in the wild. To address this gap, we present the design, implementation and validation of the EgoActive platform, which addresses limitations of existing wearable technologies for developmental research. EgoActive records the active infants' egocentric perspective of the world via a miniature wireless head-mounted camera concurrently with their physiological responses to this input via a lightweight, wireless ECG/acceleration sensor. We also provide software tools to facilitate data analyses. Our validation studies showed that the cameras and body sensors performed well. Families also reported that the platform was comfortable, easy to use and operate, and did not interfere with daily activities. The synchronized multimodal data from the EgoActive platform can help tease apart complex processes that are important for child development to further our understanding of areas ranging from executive function to emotion processing and social learning.


Asunto(s)
Dispositivos Electrónicos Vestibles , Lactante , Niño , Humanos , Programas Informáticos , Tecnología , Sistema Nervioso Autónomo
3.
BMC Med Educ ; 23(1): 585, 2023 Aug 18.
Artículo en Inglés | MEDLINE | ID: mdl-37596584

RESUMEN

BACKGROUND: The development of competencies in dentistry is a complicated process that calls for the development of not just cognitive and psychomotor abilities but also behaviors and attitudes that change as technical proficiency increases and meaningful patient encounters occur. This study examined the relationship between the number of clinical requirements completed by dental students and subsequent performance on tests of competence. The null hypothesis stated there would be no significant linear relationship different from zero between absolute clinical requirements and grades attained in various tests of clinical competence. METHODS: Retrospective assessment data for 81 students were used in this analysis. Data included the amounts of clinical requirements completed for operative dentistry, endodontics, periodontics, and fixed prosthodontics together with data on the respective performance in tests of competence. Correlation was ascertained between grades for tests of competence and the corresponding clinical requirements using a non-parametric Spearman's Rho test at an alpha level of 0.05. RESULTS: Fixed prosthodontics and posterior endodontics were the least common procedures completed by dental students. Statistically significant weak correlations were found between the amounts of clinical requirements performed for posterior endodontic(p = 0.005) and operative procedures (p = 0.006) and associated performance in tests of competence. A moderate correlation was found between the number of fixed prosthodontic procedures completed and associated performance in tests of competence. This latter correlation, however, was not statistically significant (p = 0.654). A significant weak correlation was found between requirements completed for periodontics and the associated test of competence (p = 0.04). A highly statistically significant moderate correlation was found between clinical requirements for anterior endodontics and the associated performance in the tests of competence (p < 0.001). CONCLUSION: The null hypothesis was rejected since a positive correlation was found between the absolute clinical requirements completed and grades in tests of competence. However, only a weak to moderate degree of correlation was found between the completion of clinical requirements and performance in tests of competence for common clinical procedures that new dental graduates should be able to perform.


Asunto(s)
Competencia Clínica , Endodoncia , Humanos , Estudios Retrospectivos , Curriculum , Operatoria Dental
4.
Nano Lett ; 23(5): 2023-2030, 2023 Mar 08.
Artículo en Inglés | MEDLINE | ID: mdl-36797055

RESUMEN

Topological phonons and magnons potentially enable low-loss, quantum coherent, and chiral transport of information and energy at the atomic scale. Van der Waals magnetic materials are promising to realize such states due to their recently discovered strong interactions among the electronic, spin, and lattice degrees of freedom. Here, we report the first observation of coherent hybridization of magnons and phonons in monolayer antiferromagnet FePSe3 by cavity-enhanced magneto-Raman spectroscopy. The robust magnon-phonon cooperativity in the 2D limit occurs even in zero magnetic field, which enables nontrivial band inversion between longitudinal and transverse optical phonons caused by the strong coupling with magnons. The spin and lattice symmetry theoretically guarantee magnetic-field-controlled topological phase transition, verified by nonzero Chern numbers calculated from the coupled spin-lattice model. The 2D topological magnon-phonon hybridization potentially offers a new route toward quantum phononics and magnonics with an ultrasmall footprint.

5.
BMC Med Educ ; 22(1): 703, 2022 Oct 04.
Artículo en Inglés | MEDLINE | ID: mdl-36195946

RESUMEN

Differential rewarding of work and experience has been a longtime feature of academic medicine, resulting in a series of academic disparities. These disparities have been collectively called a cultural or minority "tax," and, when considered beyond academic medicine, exist across all departments, colleges, and schools of institutions of higher learning-from health sciences to disciplines located on university campuses outside of medicine and health. A shared language can provide opportunities for those who champion this work to pool resources for larger impacts across the institution. This article aims to catalog the terms used across academic medicine disciplines to establish a common language describing the inequities experienced by Black, Latinx, American Indian/Alaska Native and Native Hawaiian/Other Pacific Islander, Women, and other underrepresented people as well as queer, disabled, and other historically marginalized or excluded groups. These ideas are specific to academic medicine in the United States, although many can be used in academic medicine in other countries. The terms were selected by a team of experts in equity, diversity, and inclusion, (EDI) who are considered national thought leaders in EDI and collectively have over 100 years of scholarship and experience in this area.


Asunto(s)
Diversidad Cultural , Medicina , Docentes Médicos , Femenino , Hawaii , Humanos , Grupos Minoritarios , Facultades de Medicina , Estados Unidos
6.
BMC Res Notes ; 15(1): 291, 2022 Sep 06.
Artículo en Inglés | MEDLINE | ID: mdl-36068583

RESUMEN

OBJECTIVE: There is great interest in developing tobacco plants containing minimal amounts of the addictive compound nicotine. Quinolate phosphoribosyltransferase (QPT) is an important enzyme both for primary (NAD production) and secondary (pyridine alkaloid biosynthesis) metabolism in tobacco. The duplication of an ancestral QPT gene in Nicotiana species has resulted in two closely related QPT gene paralogs: QPT1 which is expressed at modest levels throughout the plant, and QPT2 which is coordinately regulated with genes dedicated to alkaloid biosynthesis. This study evaluated the utility of knocking out QPT2 function as a means for producing low alkaloid tobacco plants. RESULTS: CRISPR/Cas9 vectors were developed to specifically mutate the tobacco QPT2 genes associated with alkaloid production. Greenhouse-grown qpt2 plants accumulated dramatically less nicotine than controls, while displaying only modest growth differences. In contrast, when qpt2 lines were transplanted to a field environment, plant growth and development was severely inhibited. Two conclusions can be inferred from this work: (1) QPT1 gene function alone appears to be inadequate for meeting the QPT demands of the plant for primary metabolism when grown in a field environment; and (2) the complete knockout of QPT2 function is not a viable strategy for producing agronomically useful, low nicotine tobaccos.


Asunto(s)
Alcaloides , Nicotiana , Vías Biosintéticas/genética , Regulación de la Expresión Génica de las Plantas , Nicotina , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Modificadas Genéticamente/genética , Nicotiana/genética , Nicotiana/metabolismo
8.
IEEE Trans Pattern Anal Mach Intell ; 44(9): 5747-5760, 2022 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-33956625

RESUMEN

In this paper we present methods for estimating shape from polarisation and shading information, i.e. photo-polarimetric shape estimation, under varying, but unknown, illumination, i.e. in an uncalibrated scenario. We propose several alternative photo-polarimetric constraints that depend upon the partial derivatives of the surface and show how to express them in a unified system of partial differential equations of which previous work is a special case. By careful combination and manipulation of the constraints, we show how to eliminate non-linearities such that a discrete version of the problem can be solved using linear least squares. We derive a minimal, combinatorial approach for two source illumination estimation which we use with RANSAC for robust light direction and intensity estimation. We also introduce a new method for estimating a polarisation image from multichannel data and provide methods for estimating albedo and refractive index. We evaluate lighting, shape, albedo and refractive index estimation methods on both synthetic and real-world data showing improvements over existing state-of-the-art.

9.
IEEE Trans Pattern Anal Mach Intell ; 44(7): 3659-3675, 2022 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-33560977

RESUMEN

In this paper we show how to perform scene-level inverse rendering to recover shape, reflectance and lighting from a single, uncontrolled image using a fully convolutional neural network. The network takes an RGB image as input, regresses albedo, shadow and normal maps from which we infer least squares optimal spherical harmonic lighting coefficients. Our network is trained using large uncontrolled multiview and timelapse image collections without ground truth. By incorporating a differentiable renderer, our network can learn from self-supervision. Since the problem is ill-posed we introduce additional supervision. Our key insight is to perform offline multiview stereo (MVS) on images containing rich illumination variation. From the MVS pose and depth maps, we can cross project between overlapping views such that Siamese training can be used to ensure consistent estimation of photometric invariants. MVS depth also provides direct coarse supervision for normal map estimation. We believe this is the first attempt to use MVS supervision for learning inverse rendering. In addition, we learn a statistical natural illumination prior. We evaluate performance on inverse rendering, normal map estimation and intrinsic image decomposition benchmarks.

10.
IEEE Trans Pattern Anal Mach Intell ; 43(11): 4142-4160, 2021 11.
Artículo en Inglés | MEDLINE | ID: mdl-32356737

RESUMEN

Three-dimensional morphable models (3DMMs) are powerful statistical tools for representing the 3D shapes and textures of an object class. Here we present the most complete 3DMM of the human head to date that includes face, cranium, ears, eyes, teeth and tongue. To achieve this, we propose two methods for combining existing 3DMMs of different overlapping head parts: (i). use a regressor to complete missing parts of one model using the other, and (ii). use the Gaussian Process framework to blend covariance matrices from multiple models. Thus, we build a new combined face-and-head shape model that blends the variability and facial detail of an existing face model (the LSFM) with the full head modelling capability of an existing head model (the LYHM). Then we construct and fuse a highly-detailed ear model to extend the variation of the ear shape. Eye and eye region models are incorporated into the head model, along with basic models of the teeth, tongue and inner mouth cavity. The new model achieves state-of-the-art performance. We use our model to reconstruct full head representations from single, unconstrained images allowing us to parameterize craniofacial shape and texture, along with the ear shape, eye gaze and eye color.


Asunto(s)
Imagenología Tridimensional , Reconocimiento de Normas Patrones Automatizadas , Algoritmos , Cara , Cabeza/diagnóstico por imagen , Humanos
11.
Gen Dent ; 68(5): 61-65, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32857051

RESUMEN

The aim of this research was to determine the color stability of 3 gingival shades of dental restorative materials, Amaris Gingiva, Beautiful II Gingiva, and PermaFlo Pink, compared to a tooth-colored nanohybrid composite, Filtek Z250. Twenty-five specimens of each composite were fabricated in polytetrafluoroethylene-coated stainless steel molds and polished using a 4-step polishing regimen. The specimens were randomly assigned to groups for immersion in 1 of 5 solutions (n = 5): distilled water (control), red wine, tea, coffee, or curry (curry powder [containing turmeric] in a solution with distilled water). A desktop spectrophotometer was used to perform color measurements within the Commission Internationale de l'Eclairage L*a*b* color space, and mean overall color (E*) was calculated for each group before and after immersion for 7 days. The mean E* values of each composite before and after immersion were compared using paired t tests at the P < 0.05 level of significance. For all of the tested restorative materials, immersion in a solution of curry produced the greatest increase in mean E* values (P < 0.0001), with E* increasing 32-fold for Amaris Gingiva specimens, 27-fold for Beautiful II Gingiva, 34-fold for PermaFlo Pink, and 2-fold for Filtek Z250. There were smaller, but still significant, increases in E* for Amaris Gingiva, Beautiful II Gingiva, and PermaFlo Pink when immersed in coffee (P < 0.05). Curry caused the greatest change in E* values for all of the tested restorative materials, indicating that curry seasonings based on turmeric can cause unacceptable color change in all of the tested materials and such change can happen in a relatively short time. Coffee also has the potential to cause unacceptable color change in gingival shades of composite materials.


Asunto(s)
Resinas Compuestas , Encía , Café , Color , Materiales Dentales , Ensayo de Materiales , Espectrofotometría , Propiedades de Superficie
12.
Artículo en Inglés | MEDLINE | ID: mdl-32760704

RESUMEN

Variable moisture content of biomass during storage is known to compromise feedstock stability, yet a great deal of uncertainty remains on how to manage or mitigate the issue. While moisture contents above 20% risk unacceptable losses in aerobic feed and forage storage, no quantitative relationship exists between corn stover moisture content and rates or extents of degradation for bioenergy use. This work quantifies the relationship between initial moisture content of aerobically stored corn (Zea mays L.) stover biomass and dry matter loss through time. Corn stover with 20% to 52% moisture was stored under aerobic conditions in laboratory reactors while dry matter loss was measured in real time, reaching extents of 8% to 28% by the end of storage. Rates and extents of degradation were proportional to moisture content but were not linearly related. A moisture content "threshold" exists between 36% and 52% above which rates and extents of degradation increase rapidly. Compositional changes included glucan and lignin enrichment resulting from hemicellulose component (xylan and acetyl) biodegradation. Moisture desorption characteristics of the post-storage materials suggest chemical and/or physical changes that increase biomass hydrophilicity. Monomerization of carbohydrates though dilute acid pretreatment and enzymatic hydrolysis resulted in only minor changes, suggesting that degradation does not negatively influence conversion potential of the remaining biomass. Total dry matter preservation remains one of the most significant challenges for a biorefinery.

13.
Artículo en Inglés | MEDLINE | ID: mdl-32754583

RESUMEN

Corn stover dry matter loss effects variability for biofuel conversion facility and technology sustainability. This research seeks to understand the dynamic mechanisms of the thermal system, organic matter loss, and microbial heat generation in corn stover storage operations through system dynamics, a mathematical modeling approach, and response analysis to improve the system performance. This study considers epistemic uncertainties including cardinal temperatures of microbial respiratory activity, specific degradation rate, heat evolution per unit substrate degraded, and thermal conductivity in corn stover storage reactors. These uncertainties were managed through calibration, a process of improving the agreement between the computational and benchmark experimental results by adjusting the parameters of the model. Model calibration successfully predicted the temperature of the system as quantified by the mean absolute error, 0.6°C, relative to the experimental work. The model and experimental dry matter loss after 30 days of storage were 5.1% and 4.9 ± 0.28%. The model was further validated using additional experimental results to ensure that the model accurately represented the system. Model validation obtained a temperature mean absolute relative error of 0.9 ± 0.3°C and dry matter loss relative error of 3.1 ± 1.5%. This study presents a robust prediction of corn stover storage temperature and demonstrates that an understanding of carbon sources, microbial communities, and lag-phase evolution in bi-phasic growth are essential for the prediction of organic matter preservation in corn stover storage systems under environment's variation.

14.
Artículo en Inglés | MEDLINE | ID: mdl-32582670

RESUMEN

Feedstock cost is a major variable cost component in conversion to biofuels and chemicals. Consistent feedstock quality is critically important to achieve high product yield and maximum onstream time. Traditionally, raw biomass materials are delivered directly to the biorefineries where they are preprocessed to feedstock prior to being converted to products. Since many types of biomass materials-including agricultural residues, energy crops, and logging residues-are harvested according to growth cycles and optimal harvesting time, just-in-time steady supply of raw biomass to the biorefineries is not possible. Instead, biomass materials are stored, then delivered to the biorefineries as needed. Experience to date indicates that this approach has caused many issues related to logistics, biomass losses due to microbial degradation and fire, and inconsistent feedstock quality due to variability in the properties of as-delivered biomass. These factors have led to high feedstock cost, low throughput, and low product yield for the biorefineries. Idaho National Laboratory has developed a new strategy to address the problems encountered in the traditional approach in biomass feedstock supply, storage, and preprocessing mentioned above. The key components of this strategy are (1) preservation and preconditioning of biomass during storage, (2) utilization of all the biomass, including minor components that are normally considered wastes or contaminants, and (3) maximization of the value of each component. This new approach can be accomplished using feedstock preprocessing depots located near the biomass-production sources.

15.
Int J Artif Organs ; 43(10): 677-683, 2020 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-32089074

RESUMEN

We are developing a novel type of miniaturized left ventricular assist device that is configured for transapical insertion. The aim of this study was to assess the performance and function of a new pump by using a Virtual Mock Loop system for device characterization and mapping. The results, such as pressure-flow performance curves, from pump testing in a physical mock circulatory loop were used to analyze its function as a left ventricular assist device. The Virtual Mock Loop system was programmed to mimic the normal heart condition, systolic heart failure, diastolic heart failure, and both systolic and diastolic heart failure, and to provide hemodynamic pressure values before and after the activation of several left ventricular assist device pump speeds (12,000, 14,000, and 16,000 r/min). With pump support, systemic flow and mean aortic pressure increased, and mean left atrial pressure and pulmonary artery pressure decreased for all heart conditions. Regarding high pump-speed support, the systemic flow, aortic pressure, left atrial pressure, and pulmonary artery pressure returned to the level of the normal heart condition. Based on the test results from the Virtual Mock Loop system, the new left ventricular assist device for transapical insertion may be able to ease the symptoms of patients with various types of heart failure. The Virtual Mock Loop system could be helpful to assess pump performance before in vitro bench testing.


Asunto(s)
Insuficiencia Cardíaca/fisiopatología , Corazón Auxiliar , Hemodinámica/fisiología , Modelos Cardiovasculares , Presión Arterial/fisiología , Sistema Cardiovascular/fisiopatología , Humanos
16.
IEEE Trans Pattern Anal Mach Intell ; 41(12): 2875-2888, 2019 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-30188812

RESUMEN

We present a method for estimating surface height directly from a single polarisation image simply by solving a large, sparse system of linear equations. To do so, we show how to express polarisation constraints as equations that are linear in the unknown height. The local ambiguity in the surface normal azimuth angle is resolved globally when the optimal surface height is reconstructed. Our method is applicable to dielectric objects exhibiting diffuse and specular reflectance, though lighting and albedo must be known. We relax this requirement by showing that either spatially varying albedo or illumination can be estimated from the polarisation image alone using nonlinear methods. In the case of illumination, the estimate can only be made up to a binary ambiguity which we show is a generalised Bas-relief transformation corresponding to the convex/concave ambiguity. We believe that our method is the first passive, monocular shape-from-x technique that enables well-posed height estimation with only a single, uncalibrated illumination condition. We present results on real world data, including in uncontrolled, outdoor illumination.

17.
Artículo en Inglés | MEDLINE | ID: mdl-29632861

RESUMEN

Wet anaerobic storage of corn stover can provide a year-round supply of feedstock to biorefineries meanwhile serving an active management approach to reduce the risks associated with fire loss and microbial degradation. Wet logistics systems employ particle size reduction early in the supply chain through field-chopping which removes the dependency on drying corn stover prior to baling, expands the harvest window, and diminishes the biorefinery size reduction requirements. Over two harvest years, in-field forage chopping was capable of reducing over 60% of the corn stover to a particle size of 6 mm or less. Aerobic and anaerobic storage methods were evaluated for wet corn stover in 100 L laboratory reactors. Of the methods evaluated, traditional ensiling resulted in <6% total solid dry matter loss (DML), about five times less than the aerobic storage process and slightly less than half that of the anaerobic modified-Ritter pile method. To further demonstrate the effectiveness of the anaerobic storage, a field demonstration was completed with 272 dry tonnes of corn stover; DML averaged <5% after 6 months. Assessment of sugar release as a result of dilute acid or dilute alkaline pretreatment and subsequent enzymatic hydrolysis suggested that when anaerobic conditions were maintained in storage, sugar release was either similar to or greater than as-harvested material depending on the pretreatment chemistry used. This study demonstrates that wet logistics systems offer practical benefits for commercial corn stover supply, including particle size reduction during harvest, stability in storage, and compatibility with biochemical conversion of carbohydrates for biofuel production. Evaluation of the operational efficiencies and costs is suggested to quantify the potential benefits of a fully-wet biomass supply system to a commercial biorefinery.

18.
Pediatric Dental Journal ; 27(3): 121-127, July 6, 2017. tab; graf
Artículo en Inglés | MedCarib | ID: biblio-1368639

RESUMEN

Objectives: The purpose of this study was to determine the prevalence of oral habits (both nutritive and non-nutritive) in children in Trinidad, West Indies and to determine if there are any associated factors such as age, gender, ethnicity, social/familial factors, dietary practices and parental perception. Methods: 155 children aged 4e16 years and their parents were questioned using a struc- tured interview about breast and bottle feeding history, history of oral habits, sibling habit history, parental education level and habit history and parental belief and perception. Oral habits such as pacifier use, digit sucking, tongue sucking, lip biting and sucking, nail biting, and object chewing were recorded. Results: There was a very high prevalence of oral habits (91.6%) with 63.9% of children having two or more habits. The most common oral habit was nail biting (52.9%) and ice crunching was most commonly found in females. Tongue sucking was predominant in children of African ethnicity. Oral habits were more common in children whose parents had a post primary education. 51% of parents were not concerned about oral habits and 64.5% believed that the child would stop the habit without any intervention. Conclusion: The prevalence of both nutritive and non-nutritive oral habits in Trinidad are high and some associations were found with gender, ethnicity, social, dietary and familial factors.


Asunto(s)
Humanos , Preescolar , Niño , Adolescente , Trinidad y Tobago , Odontología Pediátrica , Región del Caribe , Chupetes , Hermanos , Hielo , Labio , Hábito de Comerse las Uñas
19.
Open Journal of Stomatology ; 7(4): 250-263, April 30, 2017. tab; ilus
Artículo en Inglés | MedCarib | ID: biblio-1370684

RESUMEN

This study assessed the roughness of two injection-molded, thermoplastic materials used for denture bases compared with a polyamide material and compression molded Polymethylmethacrylate (PMMA) after the adjustment and re-polishing with either a laboratory protocol or a chair side protocol. Methods: Forty specimens, each of PMMA, Valplast, DuraFlex, Dura Cetal were fabricated and finished according to individual manufactures' instructions. These materials were adjusted with tungsten carbide (TC) burs to mimic gross adjustments, and then re-polished either on a lathe or bonded silicon carbide (B-SC). Following instrumentation, the specimens were assessed using contact profilometry and scanning electron microscopy. Two-factor ANOVA was used to determine significant differences in mean surface roughness (Ra and Rmax), with included factors being material type and re-polishing regimen. Results: Mean Ra values ranged from 0.26 (DuraFlex control) to 1.82 (Valplast adjusted with TC burs). Mean Rmax values ranged from 1.88 (Dura Flex control) to 13.76 (Valplast adjusted with TC burs). Two-factor ANOVA revealed that interaction of both factors was significant (p < 0.05) for Ra and Rmax. There was a statistically significant increase in both Ra (p < 0.05) and Rmax (p < 0.05) for all material types following the gross adjustment. With the exception of DuraFlex, re-polishing of samples that were previously adjusted with TC burs, on the dental lathe produced surfaces that were comparable to control samples. Conclusion: Adjustment of DuraFlex should be kept to a minimum since the adjustment produced the significant surface detriment that could not be corrected with either of the polishing regimens.


Asunto(s)
Humanos , Trinidad y Tobago , Bases para Dentadura , Resinas , Región del Caribe
20.
IEEE Trans Image Process ; 26(2): 711-723, 2017 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-28113757

RESUMEN

In this paper, we present a complete pipeline for computing structure-from-motion from the sequences of spherical images. We revisit problems from multiview geometry in the context of spherical images. In particular, we propose methods suited to spherical camera geometry for the spherical-n-point problem (estimating camera pose for a spherical image) and calibrated spherical reconstruction (estimating the position of a 3-D point from multiple spherical images). We introduce a new probabilistic interpretation of spherical structure-from-motion which uses the von Mises-Fisher distribution to model noise in spherical feature point positions. This model provides an alternate objective function that we use in bundle adjustment. We evaluate our methods quantitatively and qualitatively on both synthetic and real world data and show that our methods developed for spherical images outperform straightforward adaptations of methods developed for perspective images. As an application of our method, we use the structure-from-motion output to stabilise the viewing direction in fully spherical video.

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