Semiparametric Bayesian Analysis of Case–Control Data under Conditional Gene-Environment Independence

In case–control studies of gene-environment association with disease, when genetic and environmental exposures can be assumed to be independent in the underlying population, one may exploit the independence in order to derive more efficient estimation techniques than the traditional logistic regression analysis ( Chatterjee and Carroll, 2005 , Biometrika 92, 399–418). However, covariates that stratify the population, such as age, ethnicity and alike, could potentially lead to nonindependence. In this article, we provide a novel semiparametric Bayesian approach to model stratification effects under the assumption of gene-environment independence in the control population. We illustrate the methods by applying them to data from a population-based case–control study on ovarian cancer conducted in Israel. A simulation study is conducted to compare our method with other popular choices. The results reflect that the semiparametric Bayesian model allows incorporation of key scientific evidence in the form of a prior and offers a flexible, robust alternative when standard parametric model assumptions do not hold.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65893/1/j.1541-0420.2007.00750.x.pd

OGMS: A Facility to Measure Out-gassing Rate of Materials

AbstractOGMS, the OutGassing Measurement System, is a facility to measure the outgassing rates of materials. The rate is highly important factor in vacuum science dealing with systems working at pressures below 10-6 mbar. In ultra- high vacuum range it plays role in system pressure at given pumping speed. For standard materials the data is available in literature but at times not under condition of specific application. Many application use very specific materials under vacuum conditions. Cryoadsorption Cryopump a project at Institute for plasma Research uses steel samples coated with activated carbon as sorbents. Various kinds of sorbents were used. Necessity to measure the outgassing rate of such unique materials established the OGMS. The OGMS facility has a known conductance of 2.46 l/s and base outgassing rate of ∼ 3x10-12 mbar-ltr/s-cm2. An ultimate vacuum of < 5 x10-9 mbar was achieved in a sample chamber of volume ∼7.5 liters. This paper describes OGMS, its calibration, experiments to find outgassing rate of steel samples and comparison with reported data to establish authenticity for new materials. It also reports results of outgassing rates of cryo-adhesives and activated charcoal coated steel samples

Missing Exposure Data in Stereotype Regression Model: Application to Matched Case–Control Study with Disease Subclassification

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87006/1/j.1541-0420.2010.01453.x.pd

Synthesis, spectra and redox properties of mononuclear five-co-ordinate copper(II) complexes with non-communicable pyrazole/pyridyl containing ligands: X-ray structure of [2,6-bis(3,5-dimethyl-pyrazol-1-ylmethyl)pyridine][2-(3,5-dimethylpyrazol-1-ylmethyl)pyridine]copper(II) diperchlorate

Synthesis and characterization of a series of five-co-ordinate mononuclear copper(II) compounds (1-8) have been achieved using 1 tridentate / bidentate heterocyclic nitrogen donor ligands with mixed hard-soft donor sets [L1 = 2,6-bis(pyrazol-1-ylmethyl)pyridine; L2 = 2,6-bis(3,5-dimethylpyrazol-1-ylmethyl)pyridine; L3 = 2-(pyrazol-1-ylmethyl)pyridine; L4 = 2-(3,5-dimethylpyrazol-1-ylmethyl)- pyridine]. Two types of complexes have been synthesized: (i) the anion bound complexes [Cu(L1/L2 )X2] (X=Cl- 1and 2; N-3 3 and 4; SCN- 5 and 6) and (ii) mixed-ligand complexes [Cu(L1/L2)(L3/L4)](ClO4)2 7 and 8. Complexes 1-8 belong to only a handful of copper(II) complexes with this class of non-planar ligands where pyrazole and pyridine rings are separated by methylene spacer(s). A representative complex [Cu(L2)(L4)](ClO4)2 8, having CuN5 co-ordination sphere, has been structurally characterized, to reveal square pyramidal stereochemistry at the copper(II) centre. Conductivity measurements revealed that one of the co-ordinated anions in 3, 5 and 6 is dissociated in solution, with the vacant site occupied by solvent molecule. Absorption and EPR spectral features of 1-8 represent that these copper(II) complexes adopt essentially a square pyramidal geometry. However, for 1 both in the solid state as well as in solution and for 2 in solution we propose that the copper(II) centre could be six-co-ordinate. Cyclic voltammetric measurements reveal the following trends in their E&#189; values (CuII -CuI redox process): (i) relative stabilization of CuII state by anionic ligands (N-3, Cl- or NCS- ) and a strongly co-ordinating solvent like DMF and (ii) predominance of steric over electronic effect (L1 vs. L2)

Calculation of true coincidence summing correction factor for a Broad Energy Germanium (BEGe) detector using standard and fabricated sources

The true coincidence summing (TCS) correction factor for a Broad Energy Germanium (BEGe) detector has been calculated at far and close geometry measurement using multi-energetic radioactive $\gamma$-ray sources $^{60}$Co, $^{133}$Ba and $^{152}$Eu. The correction factors were calculated using experimental method and analytical method. Photopeak efficiency and total efficiency required to calculate the correction factor were obtained using Geant4 Monte Carlo simulation code. A few standard as well as fabricated mono-energetic sources were also included in the $\gamma$-ray efficiency measurements. The simulated efficiencies of mono-energetic $\gamma$-ray sources were matched to experimental $\gamma$-ray efficiencies by optimizing the detector parameters. The same parameters were used to obtain the photopeak and total efficiency for $\gamma$-ray of our interest and coincident $\gamma$-ray. Analytical correction factors and experimental correction factors were found in good agreement with each other

More of the Gut in the Lung: How Two Microbiomes Meet in ARDS

In critically ill patients, lung and gut microbiomes undergo profound changes. Lung microbiome might become enriched with gut-associated microbes as recently demonstrated in sepsis and acute respiratory distress syndrome (ARDS). It has been proposed that in these conditions, bacteria from the gut might enter the lungs via translocation, a process facilitated by increased gut and alveolo-capillary permeability. In patients requiring mechanical ventilation after severe trauma, lung microbiome enrichment with gut-associated microbes was found to correlate with the development of ARDS. The lungs in ARDS are increasingly susceptible to opportunistic infections which can further perpetuate alveolar inflammation and injury. Undoubtedly, more research on the gut-lung crosstalk in critically ill patients is needed to identify causal relationships between the altered microbiome, infections, inflammation, and acute lung injury. With further insights, this area of investigation could lead to the development of novel, microbiome-targeted, and immunomodulation strategies with the potential to improve outcomes of critically ill patients with sepsis, trauma, and ARDS

Synthesis, spectroscopy and electrochemistry of ruthenium(II) complexes of tridentate pyridylpyrazole ligands. Predominance of electronic over steric effects

The preparations and properties of bis complexes of ruthenium(II) containing various combinations of the tridentate ligands 2,6-bis(pyrazol-1-ylmethyl)pyridine (L1) and di- and tetra-methyl substituted derivatives (L2 and L3) are described. The absorption spectral properties of the complexes are thoroughly analysed. Full assignments have been made for the 1H NMR spectra of two representative complexes in CD3CN and the origins of the co-ordination-induced shifts are discussed. Cyclic voltammetric experiments (MeCN solutions) reveal reversible one-electron RuIII-RuII redox couples in the potential range 1.00-1.06 V vs. saturated calomel electrode (SCE). The occurrence of ligand-based irreversible reductions at low potentials (Ep,c values lie in the range: -1.90 to -2.20 V vs. SCE) reveals that these pyrazole-rich ligands are very poor p acceptors. The formal potentials of the RuIII-RuII couples decrease (by ca. 8 mV per methyl group) as the number of methyl groups in the ligands are increased. The decreased potential step size for [RuL(L')]2+(L,L'= L1-L3) relative to those observed for non-sterically hindered ruthenium(II) complexes reveals that in the present system steric effects due to 3-Me substituent(s) contribute to the observed effect but that electronic factors predominate over steric effects