Factor-analysis estimation of simultaneity-error models

A traditional economic simultaneous equation system, herein termed a pure-simultaneity model, is remodelled to take into account the observation errors which me often contained in the dependent (or endogenous) and predetermined variables of the system. Such a remodelled system will be called a simultaneity-error model. It is then shown that the simultaneity-error model may be transformed into a restricted factor-analysis model with Its factor loadings matrix partitioned into a non-identity submatrix and an identity submatrix of order equal to the number of common factors

Then, under a special assumption that requires the structural parameters in the transformed restricted factor-analysis model to satisfy a dingonality condition, a three-stage iterative estimation method, using the Newton-Kaphson process, is proposed to estimate the parameters of the restricted factor-analysis model. The structural coefficients of the simultaneity-error model are then derived indirectly from the stepwise factor-analysis estimates of the reduced-form coefficients, provided that the simultaneity-error model is just-identified. If it is over-identified, then the Fletcher-Powell process can be applied to carry out the maximization of the likelihood function in a single stage, as Jöreskog (1973) suggested. A simple consumption-investment model will be taken as an illustrative example.     

Vapor Pressure of Allyl Isothiocyanate and Its Transport in PVDC/PVC Copolymer Packaging Film

Equilibrium vapor pressures of allyl isothiocyanate (AIT) above pure AIT and AIT/canola oil mixtures from 15 to 45°C were estimated from AIT vapor densities using gas chromatography. Canola oil was an effective diluent for depressing AIT vapor pressure. Permeation of AIT in a PVDC/PVC copolymer film was measured using the dynamic quasi-isostatic method, and kinetics of AIT vapor sorption in the polymer were studied gravimetrically. Experiments were carried out at 25, 35 and 45°C with vapor pressures from 50 to 800 Pa. At fixed vapor activity, diffusion and permeability coefficients increased with temperature, but a decrease was observed for solubility coefficient. An empirical equation was used to describe the sorption kinetics.     

Rheology and Microstructure of Succinylated Canola Protein Isolate

Steady shear rheological properties of aqueous dispersions of unmodified and succinylated canola (rapeseed) protein (54 and 84% modification of free amino groups) were examined over a wide range of pH (3.5–11.0) and NaCl concentration (0.0–0.70M). All dispersions were pseudoplastic and followed power-law or power-law plastic flow behavior. Apparent viscosity at shear rates of 10 and 1000 s-1 was affected by extent of succinylation, pH, NaCl concentration, and interactions among these factors. At both shear rates, protein solubility and hydrophobicity were reliable predictors of apparent viscosity. Dispersion microstructure, as revealed by light microscopy, appeared to play an important role in flow behavior.     

Component Interactions in the Extrusion Cooking Process: Influence of Process Conditions on the Functional Viscosity of the Wheat Flour System

Wheat starch, vital gluten and wheat flour solubles were processed in combination, in a single screw extruder. The paste viscosity profile and degree of cook of the starch component were used to assess interactive effects. The composite of all 3 components, simulating a wheat flour, was more cooked and gave thicker pastes than wheat flour itself when processed under the same extrusion conditions. The data suggest that the integral structure of wheat flour particles imparts a greater resistance to water penetration and cooking than when the individual components exist at random in a composite formulation.     

CONSTRUCT VALIDITY FOR THE SENSATION-SEEKING SCALE.

EXAMINED THE TRAITS MEASURED BY THE SENSATION-SEEKING SCALE (SSS) BY DEFINING FACTORS WITHIN THE SCALE ITSELF AND BY CORRELATING THE SCALE WITH INDEPENDENT MEASURES OF OTHER TRAITS. 4 FACTORS WERE DEFINED IN AN EARLIER EXTENDED VERSION OF THE SSS GIVEN TO MALES: THRILL, SOCIAL, VISUAL, AND ANTISOCIAL SENSATION SEEKING. ONLY THE 1ST 2 FACTORS EMERGED CLEARLY IN THE FEMALE DATA. THE SSS WAS POSITIVELY CORRELATED WITH AUTONOMY, CHANGE, AND EXHIBITIONISM SCORES, AND NEGATIVELY CORRELATED WITH DEFERENCE, NURTURANCE, ORDERLINESS, AND AFFILIATION SCORES ON BOTH THE EPPS AND THE GOUGH-HEILBRUN ADJECTIVE CHEKC LIST (ACL). THE SSS CORRELATED POSITIVELY WITH HYPOMANIA (MMPI) AND LABILITY (ACL), AND NEGATIVELY WITH SELF-CONTROL (ACL) AND FIELD DEPENDENCY. SS IN THIS STUDY WERE 268 MALE AND 277 FEMALE UNDERGRADUATES. (22 REF.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

RELATION OF MOOD AND HYPNOTIZABILITY: AN ILLUSTRATION OF THE IMPORTANCE OF THE STATE VERSUS TRAIT DISTINCTION.

TESTED THE HYPOTHESIS THAT AFFECT STATES JUST PRIOR TO HYPNOSIS INDUCTION ARE RELATED TO SUBSEQUENT HYPNOTIZABILITY, WHILE AFFECT TRAITS ARE NOT. THE MULTIPLE AFFECT ADJECTIVE CHECKLIST (MAACL), AN AFFECT-STATE TEST, WAS GIVEN TO SS JUST PRIOR TO HYPNOSIS. MMPI AFFECT-TRAIT MEASURES WERE GIVEN AFTER HYPNOSIS. HOSTILITY STATE (MAACL) WAS SIGNIFICANTLY AND NEGATIVELY CORRELATED WITH HYPNOTIZABILITY IN 3 RUNS OF SS TESTED IN SMALL, HIGHLY MOTIVATED GROUPS. DEPRESSION STATE WAS NEGATIVELY CORRELATED WITH HYPNOTIZABILITY IN 2 OF THE RUNS, AND ANXIETY STATE WAS NEGATIVELY CORRELATED IN 1. AFFECT-STATE MEASURES WERE UNRELATED TO HYPNOTIZABILITY IN A LARGE, LESS MOTIVATED GROUP. AFFECT-TRAIT MEASURES AND OTHER TRAIT MEASURES FROM THE MMPI WERE UNRELATED TO HYPNOTIZABILITY. THE RESULTS SHOW THE IMPORTANCE OF THE STATE VS. TRAIT DISTINCTION IN THE PREDICTION OF HYPNOTIC BEHAVIOR AND HAVE IMPLICATIONS FOR OTHER AREAS OF PREDICTION. (2 P. REF.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mechanical Properties of Gellan Gels in Relation to Divalent Cations

Mechanical behavior of gels formed with gellan polymer crosslinked by calcium and magnesium ions was studied to determine the influence of divalent ion type and polymer concentration. Failure strength and deformation were measured in compression and related to concentrations of gellan and bound cations in gel matrices. Insufficient cations formed weak, extensible gels. Maximum gel strength was achieved at 0.5 divalent cations/repeat tetrasaccharide unit, assumed to be the condition for maximal numbers of complete junction zones. At optimum cation levels gels with Ca⁺⁺ were about 1.2 times stronger than gels with Mg⁺⁺ at the same polymer concentration. Excessive cations weakened the gels. Twice as much reduction in gel strength resulted from additional Ca⁺⁺ as compared to the same additional amount of Mg⁺⁺. Differences between strengths of the gels may be attributable to polymer configurations at junction zones in relation to cation size.     

Interaction Between Sodium Chloride and Paracasein as Determined by Water Sorption

The model system, salt-paracasein-water, for binding interactions that influence ripening of salted cheeses was investigated. The amount of salt interacting with protein was calculated from water sorption data in the range 0.76-0.95 a_w for the system and for pure salt and protein. Calculations showed that the components did not behave independently in that the system behaved less like salt and more like paracasein than expected, evidencing interaction between salt and protein. The amount of interacting salt increased with added salt, decreasing a_w, moisture content during preparation and drying the system. At 0.85 a_w the amount of interacted salt was 0.08 g/g protein when the salt added was 0.30; the maximum interacted salt was about 0.11.     

DETERMINATION OF PIRIMIPHOS-METHYL IN PASTA BY GAS CHROMATOGRAPHY/CHEMICAL IONIZATION MASS SPECTROMETRY

A method for the determination of pirimiphos-methyl residues in pasta has been developed. The pesticide was extracted from pasta using the Luke procedure modified for low moisture, nonfatty food products. The extracts were analyzed by capillary column gas chromatography using an ion trap mass spectrometer in the chemical ionization mode as the detector. Quantification was performed using fluorene as the internal standard. The limit of detection was 0.005 ppm. Recoveries from spaghetti were 83.0% at the 0.100 ppm level and 93.3% at the 0.010 ppm level. Of 48 spaghetti samples analyzed, 38 contained detectable residues between trace (>0.005 ppm) and 0.180 ppm. Electron ionization (EI) was used to confirm residues as low as 0.016 ppm in more concentrated extracts.