• Title/Summary/Keyword: Bayesian posterior

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Spatio-temporal Distribution of Suicide Risk in Iran: A Bayesian Hierarchical Analysis of Repeated Cross-sectional Data

  • Nazari, Seyed Saeed Hashemi;Mansori, Kamyar;Kangavari, Hajar Nazari;Shojaei, Ahmad;Arsang-Jang, Shahram
    • Journal of Preventive Medicine and Public Health
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    • v.55 no.2
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    • pp.164-172
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    • 2022
  • Objectives: We aimed to estimate the space-time distribution of the risk of suicide mortality in Iran from 2006 to 2016. Methods: In this repeated cross-sectional study, the age-standardized risk of suicide mortality from 2006 to 2016 was determined. To estimate the cumulative and temporal risk, the Besag, York, and Mollié and Bernardinelli models were used. Results: The relative risk of suicide mortality was greater than 1 in 43.0% of Iran's provinces (posterior probability >0.8; range, 0.46 to 3.93). The spatio-temporal model indicated a high risk of suicide in 36.7% of Iran's provinces. In addition, significant upward temporal trends in suicide risk were observed in the provinces of Tehran, Fars, Kermanshah, and Gilan. A significantly decreasing pattern of risk was observed for men (β, -0.013; 95% credible interval [CrI], -0.010 to -0.007), and a stable pattern of risk was observed for women (β, -0.001; 95% CrI, -0.010 to 0.007). A decreasing pattern of suicide risk was observed for those aged 15-29 years (β, -0.006; 95% CrI, -0.010 to -0.0001) and 30-49 years (β, -0.001; 95% CrI, -0.018 to -0.002). The risk was stable for those aged >50 years. Conclusions: The highest risk of suicide mortality was observed in Iran's northwestern provinces and among Kurdish women. Although a low risk of suicide mortality was observed in the provinces of Tehran, Fars, and Gilan, the risk in these provinces is increasing rapidly compared to other regions.

Ramipedicella gen. nov. (Ralfsiales, Phaeophyceae): a new crustose brown algal genus including two species, Ramipedicella miniloba sp. nov. and Ramipedicella longicellularis comb. nov.

  • Antony Otinga Oteng'o;Boo Yeon Won;Tae Oh Cho
    • ALGAE
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    • v.39 no.2
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    • pp.97-108
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    • 2024
  • The Ralfsiaceae family, part of the Ralfsiales order and consisting of crustose brown algae, includes five genera: Analipus, Endoplura, Fissipedicella, Heteroralfsia, and Ralfsia. In this study, a novel crustose genus named Ramipedicella gen. nov. is introduced within the Ralfsiaceae based on molecular and morphological analyses. Phylogenetic analyses using both concatenated dataset (rbcL + COI-5P genes) and rbcL indicate that the crustose brown algae that we collected from Korea and Russia form a unique grouping within the Ralfsiaceae. This grouping is strongly supported by both bootstrap analysis and Bayesian posterior probabilities. The genetic differences in the rbcL and COI-5P sequences between Ramipedicella and other genera within Ralfsiaceae range from 6.7 to 9.3% for rbcL and from 15.5 to 20.8% for COI-5P. Ramipedicella is characterized by crustose thalli having new crusts growing on top of old ones with a hypothallial basal layer and erect perithallial filaments, long cells with width-to-length ratio of 1 : 1-16, single chloroplast per cell, plurangia with one to several sterile cells, one to several unangia produced from unicellular stalks or from the lateral-basal region to the paraphyses, and unangia arising sequencially in irregularly branched specialized filaments. Ramipedicella, the recently identified genus, comprises two distinct species. Ramipedicella miniloba, the type species, is distinguished by crusts with small lobes, numerous hair tufts, plurangia terminated by 1-4 sterile cells, and large oblong unangia. Ramipedicella longicellularis is identified by generally smooth crusts, absence of phaeophycean hairs, plurangia terminated by 1-2 apical sterile cells, and smaller mostly oblanceolate unangia.

Development of Quantification Methods for the Myocardial Blood Flow Using Ensemble Independent Component Analysis for Dynamic $H_2^{15}O$ PET (동적 $H_2^{15}O$ PET에서 앙상블 독립성분분석법을 이용한 심근 혈류 정량화 방법 개발)

  • Lee, Byeong-Il;Lee, Jae-Sung;Lee, Dong-Soo;Kang, Won-Jun;Lee, Jong-Jin;Kim, Soo-Jin;Choi, Seung-Jin;Chung, June-Key;Lee, Myung-Chul
    • The Korean Journal of Nuclear Medicine
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    • v.38 no.6
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    • pp.486-491
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    • 2004
  • Purpose: factor analysis and independent component analysis (ICA) has been used for handling dynamic image sequences. Theoretical advantages of a newly suggested ICA method, ensemble ICA, leaded us to consider applying this method to the analysis of dynamic myocardial $H_2^{15}O$ PET data. In this study, we quantified patients' blood flow using the ensemble ICA method. Materials and Methods: Twenty subjects underwent $H_2^{15}O$ PET scans using ECAT EXACT 47 scanner and myocardial perfusion SPECT using Vertex scanner. After transmission scanning, dynamic emission scans were initiated simultaneously with the injection of $555{\sim}740$ MBq $H_2^{15}O$. Hidden independent components can be extracted from the observed mixed data (PET image) by means of ICA algorithms. Ensemble learning is a variational Bayesian method that provides an analytical approximation to the parameter posterior using a tractable distribution. Variational approximation forms a lower bound on the ensemble likelihood and the maximization of the lower bound is achieved through minimizing the Kullback-Leibler divergence between the true posterior and the variational posterior. In this study, posterior pdf was approximated by a rectified Gaussian distribution to incorporate non-negativity constraint, which is suitable to dynamic images in nuclear medicine. Blood flow was measured in 9 regions - apex, four areas in mid wall, and four areas in base wall. Myocardial perfusion SPECT score and angiography results were compared with the regional blood flow. Results: Major cardiac components were separated successfully by the ensemble ICA method and blood flow could be estimated in 15 among 20 patients. Mean myocardial blood flow was $1.2{\pm}0.40$ ml/min/g in rest, $1.85{\pm}1.12$ ml/min/g in stress state. Blood flow values obtained by an operator in two different occasion were highly correlated (r=0.99). In myocardium component image, the image contrast between left ventricle and myocardium was 1:2.7 in average. Perfusion reserve was significantly different between the regions with and without stenosis detected by the coronary angiography (P<0.01). In 66 segment with stenosis confirmed by angiography, the segments with reversible perfusion decrease in perfusion SPECT showed lower perfusion reserve values in $H_2^{15}O$ PET. Conclusions: Myocardial blood flow could be estimated using an ICA method with ensemble learning. We suggest that the ensemble ICA incorporating non-negative constraint is a feasible method to handle dynamic image sequence obtained by the nuclear medicine techniques.

Reliability Based Pile Bearing Capacity Evaluation (신뢰도에 근거한 말뚝의 지지력 평가)

  • Lee, In-Mo;Jo, Guk-Hwan;Lee, Jeong-Hak
    • Geotechnical Engineering
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    • v.11 no.1
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    • pp.9-22
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    • 1995
  • The purpose of this study is to propose safety factors of pile bearing capacity based on the reliability analysis. Each prediction method involves various degrees of uncertainties. To account for these uncertainties in a systematic way, the ratios of the measured bearing capacity from pile load tests to the predicted bearing capacity are represented in the form of a probability density function. The safety factor for each design method is obtained so that the probability of pile foundation failure is less than 10-3. The Bayesian theorem is applied in a way that the distribution using static formulae is assumed to be the A-prior and the distribution using dynamic formulae or wave equation based methods is assumed to be the likelihood, and these two are combined to obtain the posterior which has the reduced uncertainty. The results of this study show that static formulae of the pile bearing capacity using the 5.p.7. N-value as well as dynamic formulae are highly unreliable and have to have the safety factor more than 7.4 : the wave equation analysis using PDA(Pile Driving Analyzer) system the most reliable with the safety factor close to 2.7. The safety factor could be reduced certain amount by adoption the Bayes methodology in pile design.

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Genetic Contribution of Indigenous Yakutian Cattle to Two Hybrid Populations, Revealed by Microsatellite Variation

  • Li, M.H.;Nogovitsina, E.;Ivanova, Z.;Erhardt, G.;Vilkki, J.;Popov, R.;Ammosov, I.;Kiselyova, T.;Kantanen, J.
    • Asian-Australasian Journal of Animal Sciences
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    • v.18 no.5
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    • pp.613-619
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    • 2005
  • Indigenous Yakutian cattle' adaptation to the hardest subarctic conditions makes them a valuable genetic resource for cattle breeding in the Siberian area. Since early last century, crossbreeding between native Yakutian cattle and imported Simmental and Kholmogory breeds has been widely adopted. In this study, variations at 22 polymorphic microsatellite loci in 5 populations of Yakutian, Kholmogory, Simmental, Yakutian-Kholmogory and Yakutian-Simmental cattle were analysed to estimate the genetic contribution of Yakutian cattle to the two hybrid populations. Three statistical approaches were used: the weighted least-squares (WLS) method which considers all allele frequencies; a recently developed implementation of a Markov chain Monte Carlo (MCMC) method called likelihood-based estimation of admixture (LEA); and a model-based Bayesian admixture analysis method (STRUCTURE). At population-level admixture analyses, the estimate based on the LEA was consistent with that obtained by the WLS method. Both methods showed that the genetic contribution of the indigenous Yakutian cattle in Yakutian-Kholmogory was small (9.6% by the LEA and 14.2% by the WLS method). In the Yakutian-Simmental population, the genetic contribution of the indigenous Yakutian cattle was considerably higher (62.8% by the LEA and 56.9% by the WLS method). Individual-level admixture analyses using STRUCTURE proved to be more informative than the multidimensional scaling analysis (MDSA) based on individual-based genetic distances. Of the 9 Yakutian-Simmental animals studied, 8 showed admixed origin, whereas of the 14 studied Yakutian-Kholmogory animals only 2 showed Yakutian ancestry (>5%). The mean posterior distributions of individual admixture coefficient (q) varied greatly among the samples in both hybrid populations. This study revealed a minor existing contribution of the Yakutian cattle in the Yakutian-Kholmogory hybrid population, but in the Yakutian-Simmental hybrid population, a major genetic contribution of the Yakutian cattle was seen. The results reflect the different crossbreeding patterns used in the development of the two hybrid populations. Additionally, molecular evidence for differences among individual admixture proportions was seen in both hybrid populations, resulting from the stochastic process in crossing over generations.