Bayesian comparison of latent variable models: Conditional vs marginal likelihoods

Typical Bayesian methods for models with latent variables (or random effects) involve directly sampling the latent variables along with the model parameters. In high-level software code for model definitions (using, e.g., BUGS, JAGS, Stan), the likelihood is therefore specified as conditional on the latent variables. This can lead researchers to perform model comparisons via conditional likelihoods, where the latent variables are considered model parameters. In other settings, however, typical model comparisons involve marginal likelihoods where the latent variables are integrated out. This distinction is often overlooked despite the fact that it can have a large impact on the comparisons of interest. In this paper, we clarify and illustrate these issues, focusing on the comparison of conditional and marginal Deviance Information Criteria (DICs) and Watanabe-Akaike Information Criteria (WAICs) in psychometric modeling. The conditional/marginal distinction corresponds to whether the model should be predictive for the clusters that are in the data or for new clusters (where "clusters" typically correspond to higher-level units like people or schools). Correspondingly, we show that marginal WAIC corresponds to leave-one-cluster out (LOcO) cross-validation, whereas conditional WAIC corresponds to leave-one-unit out (LOuO). These results lead to recommendations on the general application of the criteria to models with latent variables.Comment: Manuscript in press at Psychometrika; 31 pages, 8 figure

Acute appendicitis and retroperitoneal abscess: rare complications of sigmoid diverticulitis

Diverticulitis is a common cause of an acute surgical abdomen and computed tomography has become an essential part of work up particularly to identify complications that commonly include intraperitoneal perforation, abscess and fistula formation. We report the case of an 81-year-old male who presented to the emergency department with acute lower abdominal pain and was found to have sigmoid diverticulitis with the rare complications of a diverticular abscess that had formed a sinus tract and perforated into the retroperitoneum and secondary acute appendicitis. Initial management was with intravenous antibiotics, a Hartmann's procedure and appendicectomy. Subsequently the retroperitoneal collection was drained percutaneously. The case was further complicated by the patient's multiple co-morbidities and unfortunately the patient died 6 weeks after admission from sepsis. This case highlights the role of computed tomography in the pre- and post-operative period to identify complications which are often clinically occult and require early surgical and interventional radiology management to optimize outcomes

High‐Tensile Strength, Composite Bijels through Microfluidic Twisting

Rope making is a millennia old technique to collectively assemble numerous weak filaments into flexible and high tensile strength bundles. However, delicate soft matter fibers lack the robustness to be twisted into bundles by means of mechanical rope making tools. Here, weak microfibers with tensile strengths of a few kilopascals are combined into ropes via microfluidic twisting. This is demonstrated for recently introduced fibers made of bicontinuous interfacially jammed emulsion gels (bijels). Bijels show promising applications in use as membranes, microreactors, energy and healthcare materials, but their low tensile strength make reinforcement strategies imperative. Hydrodynamic twisting allows to produce continuous bijel fiber bundles of controllable architecture. Modelling the fluid flow field reveals the bundle geometry dependence on a subtle force balance composed of rotational and translational shear stresses. Moreover, combining multiple bijel fibers of different compositions enables the introduction of polymeric support fibers to raise the tensile strength to tens of megapascals, while simultaneously preserving the liquid like properties of the bijel fibers for transport applications. Hydrodynamic twisting shows potentials to enable the combination of a wide range of materials resulting in composites with features greater than the sum of their parts

MEDICINSKA SKRB U SLOBODNOM OPKOLJENOM MISSOLONGIJU (1822.–1826.). JOHANN JACOB MEYER I PRVA VOJNA BOLNICA

During the siege of Missolonghi by the Ottomans the conditions of hygiene living, clothing and feeding of the vast majority of enslaved Greeks could be assessed as deprived and miserable. The humid climate and geophysical environment favored the outbreak of epidemics that further darkened an already unfavorable situation of the fighters and their families. Necessarily, the priority was to meet the military and economic needs and secondarily tackling public health issues, health care and medicine - social welfare. The inadequate infrastructure of nursing care, the limited number of health personnel and serious shortages into pharmaceutical material revealed the resolution of those doctors who provided their services during the siege. Johann Jacob Meyer, a famous Swiss philhellene, a man known as the first journalist in Greece, along with his Greek wife, contributed to the founding and organization of the first military hospital and to the improvement of the general health care during the siege of Missolonghi (1822-1826).Tijekom otomanske okupacije Missolonghija higijenski se uvjeti življenja, odijevanja i ishrane za većinu zarobljenih Grka mogu opisati oskudnima i bijednima. Vlažna klima i geofizički okoliš pogodovali su izbijanju epidemija koje su pogoršavale ionako nepovoljan položaj boraca i njihovih obitelji. Neadekvatna infrastruktura njege, ograničen broj medicinskog osoblja i ozbiljan nedostatak farmaceutskog materijala otkrivaju odlučnost liječnika koji su pružali svoje usluge tijekom okupacije. Prioritet je nužno bio zadovoljiti vojne i ekonomske potrebe, a potom riješiti problem javnog zdravlja, zdravstvene skrbi i medicine – društvenog blagostanja. Johann Jacob Meyer, glasoviti švicarski helenofil, poznat kao prvi novinar u Grčkoj, sa svojom suprugom pridonio je osnivanju i organizaciji prve vojne bolnice i poboljšanju opće zdravstvene skrbi tijekom opsade Missolonghija (1822.–1826)

Rag GTPases and phosphatidylinositol 3-phosphate mediate recruitment of the AP-5/SPG11/SPG15 complex.

Adaptor protein complex 5 (AP-5) and its partners, SPG11 and SPG15, are recruited onto late endosomes and lysosomes. Here we show that recruitment of AP-5/SPG11/SPG15 is enhanced in starved cells and occurs by coincidence detection, requiring both phosphatidylinositol 3-phosphate (PI3P) and Rag GTPases. PI3P binding is via the SPG15 FYVE domain, which, on its own, localizes to early endosomes. GDP-locked RagC promotes recruitment of AP-5/SPG11/SPG15, while GTP-locked RagA prevents its recruitment. Our results uncover an interplay between AP-5/SPG11/SPG15 and the mTORC1 pathway and help to explain the phenotype of AP-5/SPG11/SPG15 deficiency in patients, including the defect in autophagic lysosome reformation

Fitting multilevel models in complex survey data with design weights: Recommendations

Abstract Background Multilevel models (MLM) offer complex survey data analysts a unique approach to understanding individual and contextual determinants of public health. However, little summarized guidance exists with regard to fitting MLM in complex survey data with design weights. Simulation work suggests that analysts should scale design weights using two methods and fit the MLM using unweighted and scaled-weighted data. This article examines the performance of scaled-weighted and unweighted analyses across a variety of MLM and software programs. Methods Using data from the 2005–2006 National Survey of Children with Special Health Care Needs (NS-CSHCN: n = 40,723) that collected data from children clustered within states, I examine the performance of scaling methods across outcome type (categorical vs. continuous), model type (level-1, level-2, or combined), and software (Mplus, MLwiN, and GLLAMM). Results Scaled weighted estimates and standard errors differed slightly from unweighted analyses, agreeing more with each other than with unweighted analyses. However, observed differences were minimal and did not lead to different inferential conclusions. Likewise, results demonstrated minimal differences across software programs, increasing confidence in results and inferential conclusions independent of software choice. Conclusion If including design weights in MLM, analysts should scale the weights and use software that properly includes the scaled weights in the estimation.</p

Selenoprotein gene expression in an intestinal cell line during selenium depletion: a macroarray approach indicates effects on SelW and glutathione peroxidise 1.

The micronutrient selenium (Se) is incoprprated into a renage of selenoproteins involved in numerous biochemical processes within the body