Finite Mixtures of Mean-Parameterized Conway-Maxwell-Poisson Models

For modeling count data, the Conway-Maxwell-Poisson (CMP) distribution is a popular generalization of the Poisson distribution due to its ability to characterize data over- or under-dispersion. While the classic parameterization of the CMP has been well-studied, its main drawback is that it is does not directly model the mean of the counts. This is mitigated by using a mean-parameterized version of the CMP distribution. In this work, we are concerned with the setting where count data may be comprised of subpopulations, each possibly having varying degrees of data dispersion. Thus, we propose a finite mixture of mean-parameterized CMP distributions. An EM algorithm is constructed to perform maximum likelihood estimation of the model, while bootstrapping is employed to obtain estimated standard errors. A simulation study is used to demonstrate the flexibility of the proposed mixture model relative to mixtures of Poissons and mixtures of negative binomials. An analysis of dog mortality data is presented. As a generalization of the Poisson distribution and a common alternative to other discrete distributions, the Conway-Maxwell-Poisson (CMP) distribution has the flexibility to explicitly characterize data over- or under-dispersion. The mean-parameterized version of the CMP has received increasing attention in the literature due to its ability to directly model the data mean. When the mean further depends on covariates, then the mean-parameterized CMP regression model can be treated in a generalized linear models framework. In this work, we propose a mixture of mean-parameterized CMP regressions model to apply on data which are potentially comprised of subpopulations with different conditional means and varying degrees of dispersions. An EM algorithm is constructed to find maximum likelihood estimates of the model. A simulation study is performed to test the proposed mixture of mean-parameterized CMP regressions model, and to compare it to model fits using mixtures of Poisson regressions and mixtures of negative binomial regressions. An analysis of the spread of a viral infection in potato plants is performed using these different mixtures of count regressions models, where we show the mixture of mean-parameterized CMP regressions to be an effective model

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Fetal outcomes and associated factors of adverse outcomes of pregnancy in southern Chinese women with systemic lupus erythematosus.

This study aims to investigate the fetal outcomes and associated factors of adverse pregnancy outcomes (APOs) in pregnant women with systemic lupus erythematosus (SLE). Clinical data from 251 SLE patients with 263 pregnancies from 2001 to 2015 were analyzed retrospectively. APOs occurred in 70.0% of pregnancies, in which pregnancy loss occurred in 28.5%; preterm delivery occurred in 21.3%; intrauterine growth retardation occurred in 12.2%; and fetal distress occurred in 8.0%. Over time, the rate of APOs decreased from 82.8% during 2001~2005 to 59.6% during 2011~2015. In multivariate analysis, predictors of APOs included positive antiphospholipid antibodies (OR 8.4, 95% CI 1.7~40.8, P = 0.008), lower complement (OR 3.6, 95% CI 1.3~9.9, P = 0.01), hypoalbuminemia (OR 3.2, 95% CI 1.2~8.3, P = 0.02), and hypertension (OR 14.6, 95% CI 1.5~141.6, P = 0.02). The use of antimalarial medications was associated with lower risk for APOs (OR 0.3, 95% CI 0.1~0.7, P = 0.01). In total, 109 patients underwent fetal umbilical artery Doppler in the third trimester. The The adjusted systole/diastole (S/D) ratio, pulsatility index (PI) and resistance index (RI) of SLE patients with APOs were higher than that of patients without APOs (2.9±0.9 vs. 2.4±0.5, P = 0.001). Lupus pregnancy was still at high risk of APOs in terms of pregnancy loss and preterm delivery. Umbilical artery Doppler was a good monitor method for APOs in the third trimester

Fetal and Maternal Outcomes of Planned Pregnancy in Patients with Systemic Lupus Erythematosus: A Retrospective Multicenter Study

Objective. To investigate the fetal and maternal outcomes as well as predictors of APOs in women with SLE who conceived when the disease was stable, the so-called “planned pregnancy.” Methods. A retrospective multicenter study of 243 patients with SLE who underwent a planned pregnancy was performed. APOs in fetus and mothers were recorded. Results. The average age at conception was 28.9 ± 3.9 years. Duration of SLE prior to pregnancy was 4.4 ± 4.3 years. Fetal APOs occurred in 86 (86/243, 35.4%) patients. Preterm births, intrauterine growth retardation (IUGR), fetal distress, and fetal loss accounted for 22.2%, 14.8%, 11.1%, and 4.9%, respectively. Forty-two preterm infants (42/54, 77.8%) were delivered after the 34th week of gestation. All the preterm infants were viable. Fifty-two patients (52/243, 21.4%) had disease flares, among which 45 cases (45/52, 86.5%) were mild, 6 (6/52, 11.5%) were moderate, and 1 (1/52, 1.9%) was severe. Disease flares were mainly presented as active lupus nephritis (41/52, 78.8%), thrombocytopenia (10/52, 19.2%), and skin/mucosa lesions (9/52, 17.3%). Pregnancy-induced hypertension (PIH) occurred in 29 patients, among which 3 were gestational hypertension and 26 were preeclampsia. Multiple analysis showed that disease flares (OR, 8.1; CI, 3.8–17.2) and anticardiolipin antibody positivity (OR, 7.4; CI, 2.5–21.8) were associated with composite fetal APOs. Conclusion. Planned pregnancy improved fetal and maternal outcomes, presenting as a lower rate of fetal loss, more favorable outcomes for preterm infants, and less severe disease flares during pregnancy

Association of different characteristics during pregnancy with APOs: Results of univariate analysis.

<p>Association of different characteristics during pregnancy with APOs: Results of univariate analysis.</p

Demographic, laboratory, clinical manifestations of SLE pregnancies with or without preterm deliveries.

<p>Demographic, laboratory, clinical manifestations of SLE pregnancies with or without preterm deliveries.</p

Fetal outcomes in pregnant women with SLE.

<p>Fetal outcomes in pregnant women with SLE.</p

Comparison of adjusted fetal umbilical artery Doppler index between patients with and without APOs (mean±SD).

<p>Comparison of adjusted fetal umbilical artery Doppler index between patients with and without APOs (mean±SD).</p