A Bayesian propensity score adjustment for latent variable modeling and MCMC algorithm

The estimation of the differences among groups in observational studies is frequently inaccurate owing to a bias caused by differences in the distributions of covariates. In order to estimate the average treatment effects when the treatment variable is binary, Rosenbaum and Rubin [1983. The central role of the propensity score in observational studies for causal effects. Biometrika 70, 41-55] proposed an adjustment method for pre-treatment variables using propensity scores. Imbens [2000. The role of the propensity score in estimating dose-response functions. Biometrika 87, 706-710] extended the propensity score methodology for estimation of average treatment effects with multivalued treatments.However, these studies focused only on estimating the marginal mean structure. In many substantive sciences such as the biological and social sciences, a general estimation method is required to deal with more complex analyses other than regression, such as testing group differences on latent variables. For latent variable models, the EM algorithm or the traditional Monte Carlo methods are necessary. However, in propensity score adjustment, these methods cannot be used because the full distribution is not specified.In this paper, we propose a quasi-Bayesian estimation method for general parametric models that integrate out the distributions of covariates using propensity scores. Although the proposed Bayes estimates are shown to be consistent, they can be calculated by existing Markov chain Monte Carlo methods such as Gibbs sampler. The proposed method is useful to estimate parameters in latent variable models, while the previous methods were unable to provide valid estimates for complex models such as latent variable models.We also illustrated the procedure using the data obtained from the US National Longitudinal Survey of Children and Youth (NLSY1979-2002) for estimating the effect of maternal smoking during pregnancy on the development of the child's cognitive functioning.     

Mechanical properties of sinter-forged Al2O3-ZrO2 ceramics

Two kinds of composites, Al₂O₃-25 wt% ZrO₂(2 mol% Y₂O₃) (Y-ZTA), Al₂O₃-25 wt% ZrO₂(8 mol% CeO₂) (Ce-ZTA) were produced by the sinter-forging process. The effect of presintering temperature on the mechanical properties of the composites was examined. The sinter-forging process increased the room-temperature bending strength in comparison with pressureless sintering, owing to the smaller grain size in sinter-forged bodies than in pressureless sintered ones. It was found necessary to keep the presintering temperature considerably lower than sinter-forging temperature in order to improve the room-temperature strength. The strength of sinter-forged Ce-ZTA was higher than that of sinter-forged Y-ZTA. The residual surface compressive stress induced by the phase transition during grinding in Ce-ZTA was found to be effective to further improve the strength and fracture toughness.     

Analysis of the IgE-epitope of Der f 2, a major mite allergen, by in vitro mutagenesis

Der f 2 is a major mite allergen composed of 129 amino acid residues. To determine the major epitopes on Der f 2 recognized by human IgE antibodies, artificial mutations were introduced to Der f 2 protein. The IgE-binding activity of Der f 2 was significantly decreased by deletion of 10 amino acids at the N-terminus or nine amino acids at the C-terminus. Site-directed mutagenesis with a single amino acid replacement by Ala or Leu in both N- and C-terminal regions as well as a central portion was performed to generate 42 single-site mutations. Amino acid replacement around a disulfide bond of Cys8-Cys119 caused a marked decrease in IgE-binding activity. Furthermore, a distinct decrease in IgE-binding was also caused by Ala-substitution close to a disulfide bond of Cys73-Cys78 and by mutations of a few charged residues. From these results, it was concluded that the two disulfide-forming regions of Der f 2 and several charged residues are important for forming major epitope structures recognized by human IgE antibodies.     

Oligosaccharide structures formed during the hydrolysis of lactose by Aspergillus oryzae β-galactosidase

Di-, tri-, tetra-, penta- and hexasaccharides were formed during the hydrolysis of lactose by transgalactosylation reaction of Aspergillus oryzae β-galactosidase. In this study the isolation and characterization of the major constituents of tri-, tetra- and pentasaccharides are described. The structure elucidation of 3 tri-, 2 tetra- and 1 pentasaccharides was carried out by methylation analysis, mass spectrometry and ¹³C-nmr spectrometry. The trisaccharides are $\text{O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 3)-O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 4)-}\text{d}\text{-}\text{glucose}\text{(3′-}\text{galactosyl-lactose}\text{)}$, $\text{O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 6)-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 4)-}\text{d}\text{-}\text{glucose}\text{(6′-}\text{galactosyl-lactose}\text{)}$ and $\text{O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 4)-O-[β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 6)]-}\text{d}\text{-}\text{glucose}\text{(4,6-}\text{digalactosyl-glucose}\text{)}$. Tetrasaccharides are $\text{O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 6)-O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 6)-O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 4)-}\text{d}\text{-}\text{glucose}$ and $\text{O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 6)-O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 3)}$ [or $\text{O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 3)-O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 6)]-O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 4)-}\text{d}\text{-}\text{glucose}$. Pentasaccharide is $\text{O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 6)-O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 6)-O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 6)-O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 4)-}\text{d}\text{-}\text{glucose}$.     

A comparison of the grade of laryngeal visualisation;--the McCoy compared with the Macintosh and the Miller blade in adults

Effectiveness in visualization of the vocal cord during orotracheal intubation with McCoy (McC) compared with Macintosh (Min) and Miller (Mil) blades were investigated. After an institutional review board approval, 117 patients for elective surgery under general anesthesia requiring tracheal intubation were investigated. Five board certified anesthesiologists tried to visualize the vocal cord of a patient three times with the three different types of laryngoscope. Total of 351 intubation attempts were studied. The view obtained at laryngoscopy with each of the three blades was recorded as follows. Grade 1. If most of the glottis is visible. Grade 2. If only the posterior extremity of the glottis is visible. Grade 3. If no part of the glottis can be seen. Grade 4. If not even the epiglottis can be exposed. Eight-two Grade 1 views were obtained with McC, 72 with Mil and 47 with Min, respectively. Thirty-three Grade 2 views were obtained with McC, 36 with Min and 24 with Mil. Two Grade 3 views with McC, 34 with Min and 14 with Mil were obtained. Seven Grade 4 views were obtained with Mil. The grades of laryngeal visualization with McC were significantly lower than those with Min and Mil.     

An Engineered Biliverdin-Compatible Cyanobacteriochrome Enables a Unique Ultrafast Reversible Photoswitching Pathway

Cyanobacteriochromes (CBCRs) are promising optogenetic tools for their diverse absorption properties with a single compact cofactor-binding domain. We previously uncovered the ultrafast reversible photoswitching dynamics of a red/green photoreceptor AnPixJg2, which binds phycocyanobilin (PCB) that is unavailable in mammalian cells. Biliverdin (BV) is a mammalian cofactor with a similar structure to PCB but exhibits redder absorption. To improve the AnPixJg2 feasibility in mammalian applications, AnPixJg2_BV4 with only four mutations has been engineered to incorporate BV. Herein, we implemented femtosecond transient absorption (fs-TA) and ground state femtosecond stimulated Raman spectroscopy (GS-FSRS) to uncover transient electronic dynamics on molecular time scales and key structural motions responsible for the photoconversion of AnPixJg2_BV4 with PCB (Bpcb) and BV (Bbv) cofactors in comparison with the parent AnPixJg2 (Apcb). Bpcb adopts the same photoconversion scheme as Apcb, while BV4 mutations create a less bulky environment around the cofactor D ring that promotes a faster twist. The engineered Bbv employs a reversible clockwise/counterclockwise photoswitching that requires a two-step twist on ~5 and 35 picosecond (ps) time scales. The primary forward P_fr → P_o transition displays equal amplitude weights between the two processes before reaching a conical intersection. In contrast, the primary reverse P_o → P_fr transition shows a 2:1 weight ratio of the ~35 ps over 5 ps component, implying notable changes to the D-ring-twisting pathway. Moreover, we performed pre-resonance GS-FSRS and quantum calculations to identify the Bbv vibrational marker bands at ~659,797, and 1225 cm⁻¹. These modes reveal a stronger H-bonding network around the BV cofactor A ring with BV4 mutations, corroborating the D-ring-dominant reversible photoswitching pathway in the excited state. Implementation of BV4 mutations in other PCB-binding GAF domains like AnPixJg4, AM1_1870g3, and NpF2164g5 could promote similar efficient reversible photoswitching for more directional bioimaging and optogenetic applications, and inspire other bioengineering advances.     

Deposition of carbon and its hydrogenation catalyzed by nickel

Formation of carbon on nickel sheet from benzene vapor carried by hydrogen was studied at a temperature range from 520 to 730°C. A maximum rate was observed at about 630°C, above which the deposition rate decreased rapidly. The carbon formed was hydrogenated in situ. Methane was the main gaseous product and a maximum rate was observed at about 670°C. Very high reactivity of deposited carbon toward hydrogenation was ascribed to the catalytic action of nickel particles dispersed in the carbon. The hydrogenation rates were divided into three zones and possible interpretations are discussed. A mechanism which is a reverse process to deposition was suggested. The decrease of the hydrogenation rate at higher temperatures was due to the equilibrium among carbon, hydrogen and methane, where carbon was more reactive than graphite.     

Semi-1 thermoplastic interpenetrating polymer networks of physically crosslinked poly(n-butyl acrylate) and polystyrene

Poly(n-butyl acrylate) (PnBA) chemically crosslinked with tetraethylene glycol dimethacrylate (TEGDM) and physically crosslinked PnBAs produced by neutralization of poly(n-butyl acrylate-stat-acrylic acid) with NaOH or Ca(OH)₂ were prepared as a polymer I network. Each polymer I was swollen with styrene and cured in situ into semi-IPN-TEGDM, semi-IPN-Na, or semi-IPN-Ca, respectively. Both physically crosslinked polymers maintained their shapes during the swelling procedure. Dynamic mechanical spectroscopy indicated that good mixing of the two polymers took place in the semi-IPN-Ca as well as in semi-IPN-TEGDM, but a distinct phase separation occurred in the semi-IPN-Na. These results were supported by their transparent or optical opaque appearances, respectively. Annealing at 180°C developed further phase separation in the semi-IPN-Na, but very little in the semi-IPN-Ca. Analyses by the incompatibility number (based on the modulus–temperature curve) and the calculation of individual phase compositions (from the glass transition temperature shifts) were used in estimating the extent of molecular mixing.     

Orientation in uniaxially drawn polystyrene plasticized by CO2 sorption

Uniaxial drawing experiments of the polystyrene films plasticized by a sorption of compressed CO₂ gas at pressures up to about 18 MPa were carried out with strain rates ε of 0.0290 and 0.0079 s^?1. The drawing was performed successfully with draw ratio λ up to 4 at the temperatures of 308.15, 318.15, 328.15, and 338.15 K. The Hermans orientation function f of the drawn samples was determined from the dichroic ratio measured by an infrared spectrophotmeter. While f value increases with increasing ε or λ, it decreases with increasing CO₂ pressure or temperature. © 1995 John Wiley & Sons, Inc.