Limit theorems for supercritical age-dependent branching processes with neutral immigration

We consider a branching process with Poissonian immigration where individuals have inheritable types. At rate θ, new individuals singly enter the total population and start a new population which evolves like a supercritical, homogeneous, binary Crump-Mode-Jagers process: individuals have independent and identically distributed lifetime durations (nonnecessarily exponential) during which they give birth independently at a constant rateb. First, using spine decomposition, we relax previously known assumptions required for almost-sure convergence of the total population size. Then, we consider three models of structured populations: either all immigrants have a different type, or types are drawn in a discrete spectrum or in a continuous spectrum. In each model, the vector (P1,P2,…) of relative abundances of surviving families converges almost surely. In the first model, the limit is the GEM distribution with parameter θ /b.

Toward evidence-based medical statistics: Re-evaluate the efficacy of antidepressants by using Bayes factors

Introduction

Studies have been reported the similar efficacy of antidepressants (effect size around 0.3), and it is difficult for clinicians to select an antidepressant. This may partly due to the use of a p<.05 null-hypothesis significance testing (NHST) framework to evaluate “substantial evidence”. This framework only allows dichotomous conclusions and does not quantify the strength of evidence supporting efficacy. In addition, meta-analyses based on publications may offer positively biased results due to selective publications.

Objectives

Demonstrate that the Bayesian framework can provide valuable information on the strength of the evidence for drug efficacy.

Aims

Re-evaluate the efficacy of FDA-approved antidepressants applied to anxiety disorders and depression by means of Bayes factors.

Methods

To avoid selective publication, data of double-blind placebo-controlled trials for FDA-approved antidepressants for the treatment of anxiety disorders and depression were extracted from the FDA. Bayes factors (BFs) were calculated and compared with the results obtained under NHST framework.

Results

A large variance of evidence for the efficacy of antidepressants was found for both depression and anxiety disorders. Among trials providing “substantial evidence” according to the FDA for anxiety disorders, only 27 out of 59 dose groups obtained strong support for efficacy according to the typically used cut-off of BF≥20. For depression, all FDA-approved antidepressants had BF≥20, except for bupriopion. Moreover, it was shown that the tested antidepressants can be differentiated based on the strength of evidence and effect size.

Conclusions

The BFs quantified the comparative evidence base for the efficacy of antidepressants.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Enrichir les classifications en psychiatrie par les données textuelles : création d’une ontologie de la psychiatrie

Le projet Covalmo s’est développé en partenariat entre le centre hospitalier Sainte-Anne et le Laboratoire d’Ingénierie des Connaissances en e-Santé. L’objectif premier de Covalmo, situé à mi-chemin entre l’Informatique et la Médecine, est d’expliciter l’ensemble des déterminants possibles de maladies psychiatriques dans le but de contribuer au développement d’un consensus sur les catégories descriptives des troubles psychiatriques, au travers d’outils et méthodes de l’Ingénierie des Connaissances. Covalmo vise ainsi au développement d’outils répondants à deux problématiques : (1) mieux décrire les diagnostics posés et les actes pratiqués, et ainsi (2) mieux indexer les dossiers patient. L’Ingénierie des Connaissances traite de la modélisation des connaissances et des problématiques qui y sont liées. Pour cela, elle développe des ontologies informatiques, qui sont des modèles permettant de recenser, organiser et lier des concepts entre eux grâce aux relations qui les unissent. Les concepts sont des entités ayant un sens dans le domaine représenté, et les relations sont les liens sémantiques entretenus entre ces concepts. Le développement de l’ontologie du domaine de la psychiatrie, OntoPsychia, est réalisé à partir des informations contenues dans un corpus textuel composé de 8000 CRH préalablement anonymisés selon un protocole strict. L’hypothèse de base de ce travail étant que les mots et les différentes verbalisations présentes dans les textes sont des traces de la conceptualisation du domaine et peuvent être utilisés pour construire l’ontologie. Les différentes nomenclatures utilisées depuis dix ans pour annoter les dossiers patients (CIM-10, DSM, ATC) sont aussi utilisées pour enrichir l’ontologie.

La validation de l’ontologie sera effectuée par les experts du domaine, ainsi que par sa mise en opérationnalisation au sein d’applications dédiées, par exemple : indexation de comptes rendus et de dossiers patients ou découverte de profils de patients résistants aux traitements médicamenteux. Ci-dessous, un extrait du module d’OntoPsychia modélisant la vie sociale (Fig. 1).

Strain-mediated coupling in a quantum dot-mechanical oscillator hybrid system

Recent progress in nanotechnology has allowed the fabrication of new hybrid systems in which a single two-level system is coupled to a mechanical nanoresonator. In such systems the quantum nature of a macroscopic degree of freedom can be revealed and manipulated. This opens up appealing perspectives for quantum information technologies, and for the exploration of the quantum-classical boundary. Here we present the experimental realization of a monolithic solid-state hybrid system governed by material strain: a quantum dot is embedded within a nanowire that features discrete mechanical resonances corresponding to flexural vibration modes. Mechanical vibrations result in a time-varying strain field that modulates the quantum dot transition energy. This approach simultaneously offers a large light-extraction efficiency and a large exciton-phonon coupling strength g0. By means of optical and mechanical spectroscopy, we find that g0/2 π is nearly as large as the mechanical frequency, a criterion that defines the ultrastrong coupling regime.

[Prevalence, severity, and predictors of bronchopulmonary dysplasia in a cohort of very preterm infants]

OBJECTIVES

The aim of this retrospective cohort study was to determine the prevalence and severity of BPD and its predictors in a regional cohort of very preterm (VP) infants in Reunion Island.

METHODS

All autochthonous VP infants, live-born before the 33rd week of gestation (WG) between 1st January 2008 and 31st December 2009, were eligible for the study. Only VP infants surviving at least 28 days, for whom the parameters were known from birth, were included in the case-control study of predictors of moderate to severe BPD (BPDmo/s).

RESULTS

In VP infants less than 33 WG, the rate of overall BPD (3 grades of severity) was 30.7%. Among those who survived 28 days or more, the rate of BPDmo/s was 13.1% (95%CI: 10.2-15.9%). In VP infants less than 32 WG that survived at 36 WG, the prevalence of BPDmo/s was 18.2% (95% CI: 14.2-22.1%). In a fixed-effect logistic model, adjusted for gestational age, postnatal growth, and the mode of ventilation at 24h, 4 key factors were predictive of BDPmo/s: small for gestational age, surfactant, delayed energy intake, and late-onset neonatal infection. In a mixed-effect logistic model adjusted for these same cofactors, the site was associated with BPDmo/s, in line with a center-effect.

CONCLUSION

The prevalence of BPDmo/s in the mixed-race population of Reunion Island is consistent with those observed in Europe but were site-specific. In our setting, predictors of individual BPDmo/s are similar to those already identified.

Serum level of the phosphaturic factor FGF23 is associated with abdominal aortic calcification in men: the STRAMBO study

CONTEXT

Calcification inhibitor deficiencies, mineral imbalance, and phenotypic transformation of vascular cells to osteogenic cells initiate and sustain vascular calcification. Fibroblast growth factor-23 (FGF23) is a key molecule regulating mineral homeostasis.

OBJECTIVE

Our objective was to assess the association of serum FGF23 levels with mineral metabolism parameters and abdominal aortic calcification (AAC) in men.

DESIGN

This was a cross-sectional analysis in the STRAMBO cohort.

SETTING

Men holding a private health insurance cover with Mutuelle de Travailleurs de la Région Lyonnaise were included in the study.

PARTICIPANTS

Participants included male volunteers aged 20-87 (n = 1130).

INTERVENTIONS

Nonfasting blood collection was done. AAC was semiquantitatively assessed from vertebral fracture assessment scans obtained using dual-energy x-ray absorptiometry.

MAIN OUTCOME MEASURES

We evaluated the association between FGF23 concentration and AAC severity in men.

RESULTS

In 350 men aged 60 yr or younger, FGF23 levels decreased with age (r = -0.21; P < 0.001) but were not associated with any other parameter. In 780 men aged over 60 yr, serum FGF23 correlated with age (r = 0.37; P < 0.001) and, after adjustment for confounders, with glomerular filtration rate (r = -0.31; P < 0.001) and PTH levels (r = 0.25; P < 0.001). After adjustment for confounders, self-reported ischemic heart disease, diabetes mellitus as well as higher concentrations of C-reactive protein and osteoprotegerin were all associated with higher FGF23 levels. After adjustment for confounders, subjects in the highest FGF23 quartile had higher prevalence of severe AAC compared with the three lower quartiles combined (odds ratio = 1.88; 95% confidence interval = 1.22-2.85; P < 0.005).

CONCLUSIONS

In healthy older men, circulating FGF23 is associated with parameters of mineral metabolism, including bone metabolism-regulating cytokines, and with severe AAC independent of traditional risk factors.

Altered monocyte and fibrocyte phenotype and function in scleroderma interstitial lung disease: reversal by caveolin-1 scaffolding domain peptide

Interstitial lung disease (ILD) is a major cause of morbidity and mortality in scleroderma (systemic sclerosis, or SSc). Fibrocytes are a monocyte-derived cell population implicated in the pathogenesis of fibrosing disorders. Given the recently recognized importance of caveolin-1 in regulating function and signaling in SSc monocytes, in the present study we examined the role of caveolin-1 in the migration and/or trafficking and phenotype of monocytes and fibrocytes in fibrotic lung disease in human patients and an animal model. These studies fill a gap in our understanding of how monocytes and fibrocytes contribute to SSc-ILD pathology. We found that C-X-C chemokine receptor type 4-positive (CXCR4⁺)/collagen I-positive (ColI⁺), CD34⁺/ColI⁺ and CD45⁺/ColI⁺ cells are present in SSc-ILD lungs, but not in control lungs, with CXCR4⁺ cells being most prevalent. Expression of CXCR4 and its ligand, stromal cell-derived factor 1 (CXCL12), are also highly upregulated in SSc-ILD lung tissue. SSc monocytes, which lack caveolin-1 and therefore overexpress CXCR4, exhibit almost sevenfold increased migration toward CXCL12 compared to control monocytes. Restoration of caveolin-1 function by administering the caveolin scaffolding domain (CSD) peptide reverses this hypermigration. Similarly, transforming growth factor β-treated normal monocytes lose caveolin-1, overexpress CXCR4 and exhibit 15-fold increased monocyte migration that is CSD peptide-sensitive. SSc monocytes exhibit a different phenotype than normal monocytes, expressing high levels of ColI, CD14 and CD34. Because ColI⁺/CD14⁺ cells are prevalent in SSc blood, we looked for such cells in lung tissue and confirmed their presence in SSc-ILD lungs but not in normal lungs. Finally, in the bleomycin model of lung fibrosis, we show that CSD peptide diminishes fibrocyte accumulation in the lungs. Our results suggest that low caveolin-1 in SSc monocytes contributes to ILD via effects on cell migration and phenotype and that the hyperaccumulation of fibrocytes in SSc-ILD may result from the altered phenotype and migratory activity of their monocyte precursors.

Association of bone microarchitecture with parathyroid hormone concentration and calcium intake in men: the STRAMBO study

OBJECTVIE: In the elderly, vitamin D deficit, low calcium intake, and impaired bone microarchitecture are associated with higher risk of hip fracture. We assessed the association of bone microarchitecture with calcium intake and serum concentrations of 25-hydroxycholecalciferol (25OHD) and parathyroid hormone (PTH) in men.

DESIGN

Cross-sectional analysis was performed in 1064 men aged 20-87 years not taking vitamin D or calcium supplements.

METHODS

Daily calcium intake was assessed using a food frequency questionnaire. Bone microarchitecture was assessed at distal radius and tibia by high-resolution peripheral quantitative computed tomography. We measured serum and urinary levels of biochemical bone turnover markers (BTMs). Statistical models were adjusted for age, weight, height, and glomerular filtration rate.

RESULTS

In 500 men aged <65 years, lower 25OHD levels and low calcium intake were associated with lower trabecular volumetric bone mineral density (Dtrab) at the distal tibia, due to lower trabecular number (Tb.N). Low calcium intake was associated with lower cortical thickness (Ct.Th). Higher PTH level was associated with higher BTM levels. In 563 men aged ≥65 years, the highest PTH quartile was associated with lower Ct.Th (tibia), lower Dtrab (both sites), and lower Tb.N (radius) compared with the lowest quartile. Low calcium intake was associated with lower Tb.N and more heterogenous trabecular distribution. BTM positively correlated with the PTH concentration.

CONCLUSION

In older men, elevated PTH concentration is associated with high bone turnover, poor trabecular microarchitecture (radius and tibia), and, at the distal tibia, lower Ct.Th. Low calcium intake is associated with lower Tb.N and more heterogenous trabecular distribution.

From single particle to superfluid excitations in a dissipative polariton gas

Using an angle-resolved heterodyne four-wave-mixing technique, we probe the low momentum excitation spectrum of a coherent polariton gas. The experimental results are well captured by the Bogoliubov transformation which describes the transition from single particle excitations of a normal fluid to soundlike excitations of a superfluid. In a dense coherent polariton gas, we find all the characteristics of a Bogoliubov transformation, i.e., the positive and negative energy branch with respect to the polariton gas energy at rest, soundlike shapes for the excitations dispersion, intensity, and linewidth ratio between the two branches in agreement with the theory. The influence of the nonequilibrium character of the polariton gas is shown by a careful analysis of its dispersion.