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1.
PLoS One ; 15(9): e0239052, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32960924

RESUMO

Dendrochronology, the study of annual rings formed by trees and woody plants, has important applications in research of climate and environmental phenomena of the past. Since its inception in the late 19th century, dendrochronology has not had a way to quantify uncertainty about the years assigned to each ring (dating). There are, however, many woody species and sites where it is difficult or impossible to delimit annual ring boundaries and verify them with crossdating, especially in the lowland tropics. Rather than ignoring dating uncertainty or discarding such samples as useless, we present for the first time a probabilistic approach to assign expected ages with a confidence interval. It is proven that the cumulative age in a tree-ring time series advances by an amount equal to the probability that a putative growth boundary is truly annual. Confidence curves for the tree stem radius as a function of uncertain ages are determined. A sensitivity analysis shows the effect of uncertainty of the probability that a recognizable boundary is annual, as well as of the number of expected missing boundaries. Furthermore, we derive a probabilistic version of the mean sensitivity of a dendrochronological time series, which quantifies a tree's sensitivity to environmental variation over time, as well as probabilistic versions of the autocorrelation and process standard deviation. A computer code in Mathematica is provided, with sample input files, as supporting information. Further research is necessary to analyze frequency patterns of false and missing boundaries for different species and sites.


Assuntos
Biometria/métodos , Árvores/crescimento & desenvolvimento , Cronologia como Assunto , Clima , Modelos Teóricos , Fatores de Tempo , Árvores/metabolismo , Madeira
2.
PLoS One ; 15(8): e0236954, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32760106

RESUMO

To infer the parameters of mechanistic models with intractable likelihoods, techniques such as approximate Bayesian computation (ABC) are increasingly being adopted. One of the main disadvantages of ABC in practical situations, however, is that parameter inference must generally rely on summary statistics of the data. This is particularly the case for problems involving high-dimensional data, such as biological imaging experiments. However, some summary statistics contain more information about parameters of interest than others, and it is not always clear how to weight their contributions within the ABC framework. We address this problem by developing an automatic, adaptive algorithm that chooses weights for each summary statistic. Our algorithm aims to maximize the distance between the prior and the approximate posterior by automatically adapting the weights within the ABC distance function. Computationally, we use a nearest neighbour estimator of the distance between distributions. We justify the algorithm theoretically based on properties of the nearest neighbour distance estimator. To demonstrate the effectiveness of our algorithm, we apply it to a variety of test problems, including several stochastic models of biochemical reaction networks, and a spatial model of diffusion, and compare our results with existing algorithms.


Assuntos
Algoritmos , Teorema de Bayes , Biometria/métodos , Fenômenos Bioquímicos , Simulação por Computador , Funções Verossimilhança , Cadeias de Markov , Redes e Vias Metabólicas , Modelos Biológicos , Modelos Estatísticos , Método de Monte Carlo , Análise de Regressão , Processos Estocásticos
3.
Curr Opin Ophthalmol ; 31(4): 284-287, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32487810

RESUMO

PURPOSE OF REVIEW: Intraocular lens (IOL) calculations in patients with keratoconus and other keratoectatic disorders continues to be a challenge for today's cataract surgeon. In this article, we review data published over the past 18 months (June 2018 to January 2020). RECENT FINDINGS: Cataract surgery in keratoconus patients has the potential to greatly improve patients' vision. However, keratoconic eyes are notorious for unpredictable outcomes because of difficulty in obtaining proper preoperative biometry and lack of data and consensus on IOL calculation formulas that can reliable in providing the desired outcome. Recent studies suggest the Barrett II Universal calculation is the most accurate in mild-to-moderate keratoconic eyes. All studies note the level of predictability decreases with the steepness of keratometric readings. Historically, the SRK/T has been shown to provide the most reliable calculations. SUMMARY: There is still no consensus on which formula is best for IOL calculation in keratoconic eyes. On the basis of the most recent literature, we recommend using the Barrett II Universal in conjunction with the SRK/T formula for mild-to-moderate eyes. Preoperative counseling of expectations with the patient is the key to achieving a satisfied patient and avoiding an unpleasant situation in the result of refractive surprise.


Assuntos
Biometria/métodos , Extração de Catarata , Ceratocone/complicações , Lentes Intraoculares , Óptica e Fotônica , Humanos , Ceratocone/fisiopatologia , Acuidade Visual/fisiologia
4.
Curr Opin Ophthalmol ; 31(4): 253-260, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32487811

RESUMO

PURPOSE OF REVIEW: The subject of artificial intelligence has recently been responsible for the advancement of many industries including aspects of medicine and many of its subspecialties. Within ophthalmology, artificial intelligence technology has found ways of improving the diagnostic and therapeutic processes in cornea, glaucoma, retina, and cataract surgery. As demands on the modern ophthalmologist grow, artificial intelligence can be utilized to help address increased demands of modern medicine and ophthalmology by adding to the physician's clinical and surgical acumen. The purpose of this review is to highlight the integration of artificial intelligence into ophthalmology in recent years in the areas of cornea, refractive, and cataract surgery. RECENT FINDINGS: Within the realms of cornea, refractive, and cataract surgery, artificial intelligence has played a major role in identifying ways of improving diagnostic detection. In keratoconus, artificial intelligence algorithms may help with the early detection of keratoconus and other ectatic disorders. In cataract surgery, artificial intelligence may help improve the performance of intraocular lens (IOL) calculation formulas. Further, with its potential integration into automated refraction devices, artificial intelligence can help provide an improved framework for IOL formula optimization that is more accurate and customized to a specific cataract surgeon. SUMMARY: The future of artificial intelligence in ophthalmology is a promising prospect. With continued advancement of mathematical and computational algorithms, corneal disease processes can be diagnosed sooner and IOL calculations can be made more accurate.


Assuntos
Inteligência Artificial , Extração de Catarata , Doenças da Córnea/diagnóstico , Procedimentos Cirúrgicos Refrativos , Biometria/métodos , Humanos , Lentes Intraoculares , Óptica e Fotônica
5.
PLoS One ; 15(6): e0234330, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32516331

RESUMO

Presbyopia and myopia research shows a growing interest in ciliary muscle biometry using optical coherence tomography (OCT). Until now, segmentation of the ciliary muscle is often performed manually using either custom-developed programs or image processing software. Here we present a novel software for semi-automatic segmentation of the ciliary muscle. It provides direct import of OCT images in DICOM format, a standardized procedure for segmentation, image distortion correction, the export of anatomical ciliary muscle landmarks, like ciliary muscle apex and scleral spur, as well as a continuous thickness profile of the ciliary muscle as a novel way of analysis. All processing steps are stored as XML files, fostering documentation and reproducibility of research through the possibility of replicating the analysis. Additionally, CilOCT supports batch processing for the automated analysis of large numbers of images and the respective data export to tabulated text files based on the stored XML files. CilOCT was successfully applied in several studies and their results will be summarized in this paper.


Assuntos
Corpo Ciliar/diagnóstico por imagem , Processamento de Imagem Assistida por Computador/métodos , Tomografia de Coerência Óptica/métodos , Algoritmos , Biometria/métodos , Humanos , Músculo Liso/diagnóstico por imagem , Músculo Liso/metabolismo , Reprodutibilidade dos Testes , Retina/diagnóstico por imagem , Esclera/diagnóstico por imagem , Software
6.
PLoS One ; 15(6): e0233080, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32530965

RESUMO

In this paper, we produced a new family of distribution called Gull Alpha Power Family of distributions (GAPF). A Special case of GAPF is derived by considering the Weibull distribution as a baseline distribution called Gull Alpha Power Weibull distribution (GAPW). The suitability of the proposed distribution derives from its ability to model both the monotonic and non-monotonic hazard rate functions which are a common practice in survival analysis and reliability engineering. Various statistical properties were derived in addition to their special cases. The unknown parameters of the model are estimated using the maximum likelihood method. Moreover, the usefulness of the proposed distribution is supported by using two real lifetime data sets as well as simulated data.


Assuntos
Biometria/métodos , Teoria da Probabilidade , Distribuições Estatísticas , Algoritmos , Animais , Interpretação Estatística de Dados , Humanos , Funções Verossimilhança , Modelos Estatísticos , Reprodutibilidade dos Testes , Análise de Sobrevida , Fatores de Tempo
7.
PLoS One ; 15(6): e0233920, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32497132

RESUMO

INTRODUCTION: The run chart is one form of statistical process control chart that is particularly useful for detecting persistent shifts in data over time. The Anhøj rules test for shifts by looking for unusually long runs (L) of data points on the same side of the process centre (mean or median) and unusually few crossings (C) of the centre depending on the number of available data points (N). Critical values for C and L have mainly been studied in isolation. But what is really of interest is the joint distribution of C and L, which has so far only been studied using simulated data series. We recently released an R package, crossrun that calculates exact values for the joint probabilities of C and L that allowed us to study the diagnostic properties of the Anhøj rules in detail and to suggest minor adjustments to improve their diagnostic value. METHODS: Based on the crossrun R package we calculated exact values for the joint distribution of C and L for N = 10-100. Furthermore, we developed two functions, bestbox() and cutbox() that automatically seek to adjust the critical values for C and L to balance between sensitivity and specificity requirements. RESULTS: Based on exact values for the joint distribution of C and L for N = 10-100 we present measures of the diagnostic value of the Anhøj rules. The best box and cut box procedures improved the diagnostic value of the Anhøj rules by keeping the specificity and sensitivity close to pre-specified target values. CONCLUSIONS: Based on exact values for the joint distribution of longest run and number of crossings in random data series this study demonstrates that it is possible to obtain better diagnostic properties of run charts by making minor adjustment to the critical values for C and L.


Assuntos
Biometria , Biometria/métodos , Técnicas e Procedimentos Diagnósticos , Humanos , Funções Verossimilhança , Probabilidade , Sensibilidade e Especificidade
8.
PLoS One ; 15(5): e0232822, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32392233

RESUMO

Populations often show complex spatial and temporal dynamics, creating challenges in designing and implementing effective surveys. Inappropriate sampling designs can potentially lead to both under-sampling (reducing precision) and over-sampling (through the extensive and potentially expensive sampling of correlated metrics). These issues can be difficult to identify and avoid in sample surveys of fish populations as they tend to be costly and comprised of multiple levels of sampling. Population estimates are therefore affected by each level of sampling as well as the pathway taken to analyze such data. Though simulations are a useful tool for exploring the efficacy of specific sampling strategies and statistical methods, there are a limited number of tools that facilitate the simulation testing of a range of sampling and analytical pathways for multi-stage survey data. Here we introduce the R package SimSurvey, which has been designed to simplify the process of simulating surveys of age-structured and spatially-distributed populations. The package allows the user to simulate age-structured populations that vary in space and time and explore the efficacy of a range of built-in or user-defined sampling protocols to reproduce the population parameters of the known population. SimSurvey also includes a function for estimating the stratified mean and variance of the population from the simulated survey data. We demonstrate the use of this package using a case study and show that it can reveal unexpected sources of bias and be used to explore design-based solutions to such problems. In summary, SimSurvey can serve as a convenient, accessible and flexible platform for simulating a wide range of sampling strategies for fish stocks and other populations that show complex structuring. Various statistical approaches can then be applied to the results to test the efficacy of different analytical approaches.


Assuntos
Biometria/métodos , Modelos Estatísticos , População , Animais , Viés , Simulação por Computador , Interpretação Estatística de Dados , Humanos , Inquéritos e Questionários
9.
Invest Ophthalmol Vis Sci ; 61(4): 34, 2020 04 09.
Artigo em Inglês | MEDLINE | ID: mdl-32334434

RESUMO

Purpose: To examine 2-year progression rate and associated biometric changes in highly myopic eyes. Methods: This is a longitudinal, observational cohort study that included 657 participants aged 7 to 70 years with bilateral high myopia (≤-6.00 diopters [D]) and followed for 2 years. All participants underwent ocular biometry and cycloplegic refraction examinations. Main outcome measures were changes in spherical equivalent refraction (SE) and ocular biometry in the right eyes. Results: Mean age of participants was 21.6 ± 12.2 years. At baseline, mean SE was -9.82 ± 3.28 D and ocular biometric measurements were 27.40 ± 1.56 mm for axial length, 3.16 ± 0.27 mm for anterior chamber depth, 3.60 ± 0.35 mm for lens thickness, and 20.09 ± 1.50 mm for vitreous chamber depth. After 2 years of follow-up, there was a trend toward more myopia and greater axial elongation in all age groups. Younger participants (≤20 years) had significantly (P < 0.001) greater rates of myopic shift and axial elongation compared with older participants (>20 years). However, highly myopic adults aged 40 to 70 years continued to demonstrate refractive progression, particularly if they had extremely high myopia (≤-10.00 D). In the multiple regression analysis, each additional diopter of myopia at baseline was associated with a 11% higher risk of a >1.00-D/y myopic shift (odds ratio, 1.11; 95% confidence interval, 1.04-1.18; P = 0.002). Conclusions: Longitudinal data from this large Chinese cohort suggest that highly myopic eyes continue to progress in SE throughout life, with the greatest rates of progression observed in younger participants. Axial elongation rates appeared to stabilize after 20 years of age and were predominantly due to an increase in the vitreous chamber depth. Other risk factors for a myopic shift included a higher degree of myopic refraction at baseline.


Assuntos
Progressão da Doença , Miopia/fisiopatologia , Refração Ocular , Testes Visuais/métodos , Adolescente , Adulto , Fatores Etários , Idoso , Biometria/métodos , Criança , China , Estudos de Coortes , Feminino , Seguimentos , Humanos , Modelos Logísticos , Estudos Longitudinais , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Miopia/patologia , Fatores de Tempo , Adulto Jovem
10.
Sensors (Basel) ; 20(5)2020 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-32121182

RESUMO

Image quality is a key issue affecting the performance of biometric systems. Ensuring the quality of iris images acquired in unconstrained imaging conditions in visible light poses many challenges to iris recognition systems. Poor-quality iris images increase the false rejection rate and decrease the performance of the systems by quality filtering. Methods that can accurately predict iris image quality can improve the efficiency of quality-control protocols in iris recognition systems. We propose a fast blind/no-reference metric for predicting iris image quality. The proposed metric is based on statistical features of the sign and the magnitude of local image intensities. The experiments, conducted with a reference iris recognition system and three datasets of iris images acquired in visible light, showed that the quality of iris images strongly affects the recognition performance and is highly correlated with the iris matching scores. Rejecting poor-quality iris images improved the performance of the iris recognition system. In addition, we analyzed the effect of iris image quality on the accuracy of the iris segmentation module in the iris recognition system.


Assuntos
Iris/fisiologia , Reconhecimento Fisiológico de Modelo/fisiologia , Algoritmos , Identificação Biométrica/métodos , Biometria/métodos , Bases de Dados Factuais , Humanos , Processamento de Imagem Assistida por Computador/métodos , Luz
11.
Am J Ophthalmol ; 218: 320-329, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32209342

RESUMO

PURPOSE: To evaluate the features of the axial length-to-corneal radius (AL/CR) ratio in Japanese patients with cataracts and to determine the accuracy of intraocular lens (IOL) power calculation formulas according to the AL/CR features and the axial length (AL). DESIGN: Retrospective observational case series. METHODS: Setting was a clinical practice. Patient population was a total of 1,135 eyes (1,135 patients) with cataracts. Observation procedures included measurement of the AL and corenal radius (CR) by optical biometry and evaluation of the refractive outcomes by using the SRK/T, Holladay 1, Hoffer Q, Haigis, and Barrett Universal II formulas. Main outcome measurements were the features of the AL/CR ratio and the accuracy of IOL power calculations based on the AL/CR ratio and the AL. RESULTS: The mean AL/CR ratio was 3.15 ± 0.19. Significant weak negative correlations were observed between the spherical equivalent (SE) and AL (r = -0.7489; P < .001) and between the SE and AL/CR ratio (r = -0.8069; P < .001); no correlation was found between the SE and CR (r = 0.0208, P = .483). For medium ALs and high AL/CR ratios, the SRK/T formula performed less accurately. For long ALs and high AL/CR ratios, the Holladay 1 and Hoffer Q formulas performed less accurately. The Barrett Universal II formula performed well across a range of ALs and AL/CR ratios. CONCLUSIONS: The AL/CR ratio explained the total variation in the SE better than the AL alone. Surgeons should pay attention to the selection of IOL power calculation formulas in eyes with high AL/CR ratios.


Assuntos
Grupo com Ancestrais do Continente Asiático/etnologia , Comprimento Axial do Olho/patologia , Biometria/métodos , Catarata/etnologia , Córnea/patologia , Lentes Intraoculares , Óptica e Fotônica , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Japão/epidemiologia , Implante de Lente Intraocular , Masculino , Pessoa de Meia-Idade , Facoemulsificação , Reprodutibilidade dos Testes , Estudos Retrospectivos , Tomografia de Coerência Óptica
12.
Am J Ophthalmol ; 214: 110-118, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32171766

RESUMO

PURPOSE: To evaluate the performance of Holladay 1 and SRK/T formulas with the axial length (AL) adjustment methods including the linear and nonlinear versions of Wang-Koch AL adjustment methods and Cooke-modified AL (CMAL); and to determine whether the CMAL should be extended to the latest Barrett Universal II, Ladas Super formula (LSF), and Emmetropia Verifying Optical formulas in highly myopic eyes. DESIGN: Retrospective, consecutive case-series study. METHODS: A total of 164 eyes of 164 patients with AL ≥26.0 mm were included and divided into 2 groups: AL <28.0 mm (Group 1) and AL ≥28.0 mm (Group 2). The average arithmetic spherical equivalent prediction error (PE), mean absolute PE, median absolute error (MedAE), and the percentage of eyes within ±0.25 diopter (D), ±0.50 D, and ±1.0 D of PE were determined. RESULTS: The Holladay 1 formulas showed the smallest MedAE when combined with the first linear or nonlinear version of Wang-Koch AL adjustment methods, both in total and in subgroups. The SRK/T formula displayed the highest prediction accuracy in combination with the first linear version of Wang-Koch adjustment method in total and subgroups. The CMAL reduced the absolute PE of LSF in total (P = .003) and in Group 1 (P = .017). CONCLUSIONS: The Holladay 1 and SRK/T formulas combined with specific AL adjustment methods had accuracy similar to the fourth-generation formulas for highly myopic eyes. Moreover, the CMAL can improve the accuracy of the LSF for highly myopic eyes.


Assuntos
Comprimento Axial do Olho/patologia , Biometria/métodos , Implante de Lente Intraocular , Lentes Intraoculares , Miopia Degenerativa/patologia , Facoemulsificação , Idoso , Catarata/patologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Óptica e Fotônica , Estudos Retrospectivos , Acuidade Visual
13.
Invest Ophthalmol Vis Sci ; 61(3): 19, 2020 03 09.
Artigo em Inglês | MEDLINE | ID: mdl-32176269

RESUMO

Purpose: The purpose of this study was to analyze the clinical features of dome-shaped macula (DSM) in highly myopic eyes and its morphological relationship with myopic retinoschisis (MRS). Methods: In this cross-sectional study, 409 eyes of 409 patients with high myopia who had spectral-domain optical coherence tomography (OCT) examinations were included. The associations of DSM with the distribution of MRS and ocular biometry were evaluated. Results: Of 409 eyes, DSM was detected in 64 eyes (15.6%). The eyes with DSM were more myopic (-18.8 ± 3.9 vs. -13.4 ± 5.9; P < 0.001) and had longer axial length (31.7 ± 2.4 vs. 29.5 ± 2.5; P < 0.001) compared with those without DSM. A higher rate of extrafoveal retinoschisis (35.9% vs. 9.6%; P < 0.001) and a lower rate of foveoschisis (10.9% vs. 26.1%; P = 0.01) were detected in the eyes with DSM compared with those without DSM. In the eyes with DSM, MRS was detected in 30 eyes (46.9%). MRS predominantly affected the extrafoveal area (76.7%), especially the base of the dome (82.6%). The extrafoveal retinoschisis was most frequently distributed in the superior quadrant (52.2%). None of the eyes with DSM displayed fovea-only retinoschisis. The ratio of the height and width of the macular bulge was higher in eyes with MRS than those without MRS (0.05 vs. 0.04; P = 0.001). Conclusions: A DSM is found in highly myopic eyes with a longer axial length. MRS in eyes with DSM is more likely to affect the extrafoveal area, especially the base of the dome. A steeper macular bulge is associated with the occurrence of MRS.


Assuntos
Macula Lutea/patologia , Miopia/complicações , Retinosquise/etiologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Biometria/métodos , Criança , Pré-Escolar , Estudos Transversais , Feminino , Humanos , Macula Lutea/diagnóstico por imagem , Masculino , Pessoa de Meia-Idade , Miopia/diagnóstico por imagem , Miopia/patologia , Retinosquise/diagnóstico por imagem , Retinosquise/patologia , Tomografia de Coerência Óptica/métodos , Adulto Jovem
14.
PLoS One ; 15(3): e0229564, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32119688

RESUMO

The introduction of high-yielding semi-dwarf varieties of wheat into cultivation has led to a "green revolution." This has required intensive research into various sources of dwarfism in wheat. However, there has been very little advancement in research on dwarfing genes in rye in comparison to wheat or barley. So far, three dominant dwarfing genes (Ddw1, Ddw3, and Ddw4) and three recessive genes (ct1, ct2, and np) have been characterized and precisely mapped in rye. There is no complete catalog of dwarfing genes available in rye. This paper presents an identification of the source of dwarfism and preliminary characterization of the new recessive gene dw9 from the BK-1 line. The gene was mapped on the long arm of the 6R chromosome and belongs to the GA-insensitive group. The initial characterization of the influence of this gene on morphological traits shows that it significantly affects the decrease of yielding trait parameters. A full evaluation can be performed after detailed breeding studies.


Assuntos
Nanismo/genética , Secale/genética , Biometria/métodos , Mapeamento Cromossômico/métodos , Cromossomos de Plantas/genética , Resistência à Doença/genética , Genes de Plantas/genética , Genes Recessivos/genética , Fenótipo , Melhoramento Vegetal/métodos , Doenças das Plantas/genética
15.
Sensors (Basel) ; 20(5)2020 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-32131494

RESUMO

Face recognition functions are today exploited through biometric sensors in many applications, from extended security systems to inclusion devices; deep neural network methods are reaching in this field stunning performances. The main limitation of the deep learning approach is an inconvenient relation between the accuracy of the results and the needed computing power. When a personal device is employed, in particular, many algorithms require a cloud computing approach to achieve the expected performances; other algorithms adopt models that are simple by design. A third viable option consists of model (oracle) distillation. This is the most intriguing among the compression techniques since it permits to devise of the minimal structure that will enforce the same I/O relation as the original model. In this paper, a distillation technique is applied to a complex model, enabling the introduction of fast state-of-the-art recognition capabilities on a low-end hardware face recognition sensor module. Two distilled models are presented in this contribution: the former can be directly used in place of the original oracle, while the latter incarnates better the end-to-end approach, removing the need for a separate alignment procedure. The presented biometric systems are examined on the two problems of face verification and face recognition in an open set by using well-agreed training/testing methodologies and datasets.


Assuntos
Face/fisiologia , Reconhecimento Facial/fisiologia , Algoritmos , Identificação Biométrica/métodos , Biometria/métodos , Confidencialidade , Bases de Dados Factuais , Destilação , Humanos , Aprendizado de Máquina , Redes Neurais de Computação
16.
Sensors (Basel) ; 20(3)2020 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-32023973

RESUMO

Although access control based on human face recognition has become popular in consumer applications, it still has several implementation issues before it can realize a stand-alone access control system. Owing to a lack of computational resources, lightweight and computationally efficient face recognition algorithms are required. The conventional access control systems require significant active cooperation from the users despite its non-aggressive nature. The lighting/illumination change is one of the most difficult and challenging problems for human-face-recognition-based access control applications. This paper presents the design and implementation of a user-friendly, stand-alone access control system based on human face recognition at a distance. The local binary pattern (LBP)-AdaBoost framework was employed for face and eyes detection, which is fast and invariant to illumination changes. It can detect faces and eyes of varied sizes at a distance. For fast face recognition with a high accuracy, the Gabor-LBP histogram framework was modified by substituting the Gabor wavelet with Gaussian derivative filters, which reduced the facial feature size by 40% of the Gabor-LBP-based facial features, and was robust to significant illumination changes and complicated backgrounds. The experiments on benchmark datasets produced face recognition accuracies of 97.27% on an E-face dataset and 99.06% on an XM2VTS dataset, respectively. The system achieved a 91.5% true acceptance rate with a 0.28% false acceptance rate and averaged a 5.26 frames/sec processing speed on a newly collected face image and video dataset in an indoor office environment.


Assuntos
Biometria/métodos , Reconhecimento Facial/fisiologia , Reconhecimento Automatizado de Padrão/métodos , Algoritmos , Inteligência Artificial , Face/anatomia & histologia , Humanos , Aumento da Imagem , Interpretação de Imagem Assistida por Computador/métodos
18.
PLoS One ; 15(2): e0229578, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32084240

RESUMO

Primary data collected during a research study is often shared and may be reused for new studies. To assess the extent of data sharing in favourable circumstances and whether data sharing checks can be automated, this article investigates summary statistics from primary human genome-wide association studies (GWAS). This type of data is highly suitable for sharing because it is a standard research output, is straightforward to use in future studies (e.g., for secondary analysis), and may be already stored in a standard format for internal sharing within multi-site research projects. Manual checks of 1799 articles from 2010 and 2017 matching a simple PubMed query for molecular epidemiology GWAS were used to identify 314 primary human GWAS papers. Of these, only 13% reported the location of a complete set of GWAS summary data, increasing from 3% in 2010 to 23% in 2017. Whilst information about whether data was shared was typically located clearly within a data availability statement, the exact nature of the shared data was usually unspecified. Thus, data sharing is the exception even in suitable research fields with relatively strong data sharing norms. Moreover, the lack of clear data descriptions within data sharing statements greatly complicates the task of automatically characterising shared data sets.


Assuntos
Biometria/métodos , Estudo de Associação Genômica Ampla/tendências , Disseminação de Informação/métodos , Bases de Dados Genéticas/estatística & dados numéricos , Bases de Dados Genéticas/tendências , Humanos , Relatório de Pesquisa
19.
PLoS One ; 15(1): e0227334, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31929562

RESUMO

The objective of this work is to advance the understanding of helicopter accidents by examining and quantifying the association between helicopter-specific configurations (number of main rotor blades, number of engines, rotor diameter, and takeoff weight) and the likelihood of accidents. We leverage a dataset of 8,338 turboshaft helicopters in the U.S. civil fleet and 825 accidents from 2005 to 2015. We use the dataset to develop a logistic regression model using the method of purposeful selection, which we exploit for inferential purposes and highlight the novel insights it reveals. For example, one important question for the design and acquisition of helicopters is whether twin-engine turboshaft helicopters exhibit a smaller likelihood of accidents than their single-engine counterparts, all else being equal. The evidence-based result we derive indicates that the answer is contingent on other covariates, and that a tipping point exists in terms of the rotor diameter beyond which the likelihood of accidents of twin-engines is higher (worse) than that of their single-engine counterparts. Another important result derived here is the association between the number of main rotor blades and likelihood of accidents. We found that for single-engine turboshaft helicopters, the four-bladed ones are associated with the lowest likelihood of accidents. We also identified a clear coupling between the number of engines and the rotor diameter in terms of likelihood of accidents. In summary, we establish important relationships between the different helicopter configurations here considered and the likelihood of accident, but these are associations, not causal in nature. The causal pathway, if it exists, may be confounded or mediated by other variables not accounted for here. The results provided here lend themselves to a rich set of interpretive possibilities, and because of their significant safety implications they deserve careful attention from the rotorcraft community.


Assuntos
Acidentes Aeronáuticos/estatística & dados numéricos , Aeronaves/estatística & dados numéricos , Biometria/métodos , Modelos Logísticos , Resgate Aéreo/estatística & dados numéricos , Humanos
20.
PLoS One ; 15(1): e0227638, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31935241

RESUMO

PURPOSE: To compare the accuracy of the five commonly used intraocular lens (IOL) calculation formulas integrated to a swept-source optical biometer, the IOLMaster 700, and evaluate the extent of bias within each formula for different ocular biometric measurements. METHODS: The study included patients undergoing cataract surgery with a ZCB00 IOL implant, using IOLMaster 700 optical biometry. A single eye per patient was included in the final analysis for a total of 324 cases. The SRK/T, Hoffer Q, Haigis, Holladay 2, and Barrett Universal II formulas were evaluated. The correlations between the refractive prediction errors calculated using the five formulas and ocular dimensions such as axial length (AL), anterior chamber depth (ACD), corneal power, and lens thickness (LT) were analyzed. RESULTS: There were significant differences in the median absolute error predicted by the five formulas after the adjustment for mean refractive prediction errors to zero (P = 0.038). The Barrett Universal II formula had the lowest median absolute error (0.263) and resulted in a higher percentage of eyes with prediction errors within ±0.50 D, ±0.75 D, and ±1.00 D (all P < 0.050). The refractive errors predicted by only the Barrett formula showed no significant correlation with the ocular dimensions: AL, ACD, corneal power, and LT. CONCLUSIONS: Overall, the Barrett Universal II formula, integrated to a swept-source optical biometer had the lowest prediction error and appeared to have the least bias for different ocular biometric measurements for the ZCB00 IOL.


Assuntos
Biometria/métodos , Lentes Intraoculares/normas , Testes Visuais/métodos , Adulto , Idoso , Idoso de 80 Anos ou mais , Comprimento Axial do Olho , Extração de Catarata/métodos , Córnea/fisiologia , Feminino , Humanos , Implante de Lente Intraocular/métodos , Cristalino/fisiologia , Masculino , Pessoa de Meia-Idade , Miopia/cirurgia , Facoemulsificação/métodos , Registros , Refração Ocular/fisiologia , Erros de Refração/diagnóstico , Procedimentos Cirúrgicos Refrativos/métodos , Reprodutibilidade dos Testes , República da Coreia , Estudos Retrospectivos , Acuidade Visual/fisiologia
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