Age, education, and the internal consistency of personality scales.

Investigated whether the internal consistencies of personality scales increase with age and education and, if so, what causes these increases. Between 96 and 106 respondents in each of the age groups 13–24 yrs, 15–26 yrs, 17–28 yrs, and 19–20 yrs and 198 adults (aged 21–25 yrs) with varying amounts of formal education completed the Taylor Manifest Anxiety Scale, the California F-Scale, the Marlowe-Crowne Social Desirability Scale, a dogmatism scale, the Extraversion subscale of the Eysenck Personality Inventory, a self-monitoring scale, and a private self-conscious scale. Results show that age and education were both linearly related to the internal consistency with which Ss responded to all 8 personality scales. The relations were stronger for education than for age, the correlations between individuals' consistency scores across scales revealed a strong consistency response set. Stepwise regression showed that this internal consistency was related to age, education, the failure to understand items, and private self-consciousness. These last 2 contributions suggest that lower consistencies are partly a measurement problem and partly due to real lower personality consistencies on trait constructs. It is suggested that, because most personality research has used nonadults, the lower internal consistency of the younger Ss has contributed to the limited predictive power of personality scales. (35 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Single photon scatter compensation by photopeak energy distribution analysis

Scattered photons degrade nuclear medicine image contrast and resolution, and preclude simple attenuation corrections. Current scatter correction methods utilize detected events with energies below pulse height analyzer (PHA) window levels, making attenuation corrections source position dependent. This new scatter rejection technique analyzes only the photon signals occurring within the range of standard PHA windows. In real time, at each image location the PHA window energy distribution is analyzed, a scatter fraction determined, and a scatter corrected number of events are output. The method can be adapted to any imaging system which produces event location and energy signals. Attenuation corrections (u=0.15 cm(-1), 140 keV) are within 6% for 2-10 cm depths.     

Propagating discrete breathers in forced one-dimensional granular networks: theory and experiment

We study propagating discrete breathers in forced one-dimensional nonlinear granular media on linear elastic foundations, with no pre-compression. These are modulated oscillatory travelling wavepackets that are formed due to the dynamical balance between the strongly nonlinear Hertzian interactions between the beads of the granular chain, the dispersion caused by the on-site elastic potential, and the intrinsic discreteness of the medium. In the theoretical part of this study we consider granular chains with and without dissipative terms. We analytically prove the existence of breathers in harmonically forced granular chains governed by nonlinear combination resonances in the forced dynamics. Our analytical models predict the speed and frequency contents of the discrete breathers which are validated by direct computational results. We show the existence of countable infinities of breathers in these systems corresponding to higher-order resonances between the applied harmonic excitations and the intrinsic frequency components of the modulated wavepackets. These families are energy-dependent and tunable with the harmonic excitation. Finally, we experimentally validate the theoretical results with a fixture that is designed to realize robustly the predicted propagating breathers. Considering impulsive excitations we experimentally verify the energy tunability of the breathers, and compare the experimental results to computational reconstructions of the results. These findings pave the way for designing granular chains for predictable and focused energy transmission.     

Aerosolization of Bacterial Spores with Pressurized Metered Dose Inhalers

Bioaerosol detection and identification systems need to be periodically checked for assurance that they are responsive to aerosol challenges. Herein, pressurized metered dose inhalers (pMDIs) containing ethanol suspensions of two simulants for B. anthracis spores are considered for providing suitable aerosols. Doses and shot weights from pMDIs with canisters having volumes equal to that of 200 metering-valve actuations were constant for ≤165 actuations, but drop beyond that range. There were statistically significant dose variations between replicate pMDIs and between two types of actuators used on the pMDIs. The storage half-lives of pMDIs filled with Bacillus atrophaeus (BG) and Bacillus thuringiensis subsp. israelensis (Bti) spore formulations are predicted to be 32 and 136 months, respectively, if the canisters are stored under refrigeration (4°C). The prediction is based on use of a logarithmic regression model relating CFU per actuation to storage time, with data taken at times of 1–12 months. Demonstration of the utility of the concept was provided by producing responses from a polymerase chain reaction (PCR) identifier with pMDI-generated BG and Bti aerosols that were collected with a 100 L/min wetted wall bioaerosol sampling cyclone.

Copyright 2013 American Association for Aerosol Research     

Study of Scale-Removal Methods in a Double-Pipe Heat Exchanger

The objective of the present study was to examine the effectiveness of four cleaning methods for the removal of tube-side fouling in a double-pipe heat exchanger. The four cleaning methods are (1) hydrolazing with 10,000-psi head pressure, (2) hydrolazing with 20,000-psi head pressure, (3) chemical cleaning, and (4) brush punching. Fouled tubes were prepared using water from a cooling tower. Each test started with a brand new tube. When the overall heat transfer coefficient dropped by 40% from the initial peak value, scales in the fouled tubes were removed using one of the above four methods. Both the overall heat transfer coefficient and inside diameter were measured before and after fouling, by which the effectiveness of a particular cleaning method was evaluated. The chemical cleaning method was found to be most effective, whereas the brush punching was least effective. When a fouled tube was kept dry, brush punching completely removed scales, indicating that surface wetness plays an important role in scale removal.     

In-Line Impactor Inlet for Bioaerosol Sampling

The proof of concept of a novel in-line real impactor (IRI) for preseparation of large particles in ambient inlets was demonstrated with a 1,250 L/min design. Numerical simulations predicted a cutpoint Stokes number 0.3 for a ratio of jet-to-plate spacing to jet width (S/W) of 2.0 and 0.5 for a ratio of 4.0. This variation in cutpoint Stokes number allows minor adjustments in cutpoint for a given device size. Experimental benchmark tests support the prediction of a shift in cutpoint with S/W. Inlet systems with flow rates of 100 and 400 L/min were designed by Stokes scaling of the 1,250 L/min IRI and integrating the lower flow devices with an existing inlet aspiration section and an insect screen. Experiments with the inlet system were conducted in a wind tunnel with particles from 3 to 20 μm aerodynamic diameter (AD) and wind speeds of 2, 8, and 24 km/h. A nominal cutpoint of approximately 11 μm AD was selected to accommodate bioaerosol sampling needs, and the wind tunnel results showed the average cutpoints of the 100 and 400 L/min inlet systems at the three wind speeds were 11.2 and 11.6 μm AD, respectively. Stand-alone tests with the 100 and 400 L/min IRIs were conducted where dry dusts (Arizona road dust/fine and coarse) were impacted on three types of collection surfaces (dry, grease-coated, and oil-soaked porous surfaces) to characterize solid particle carryover. The oil-soaked porous media allowed the least carryover of large solid particles.     

Stable adaptive identification of fully-coupled second-order 6 degree-of-freedom nonlinear plant models for underwater vehicles: Theory and experimental evaluation

This article reports the development, stability analysis, and experimental evaluation of a novel adaptive identification (AID) algorithm for underwater vehicles (UVs) for on-line estimation of plant parameters (hydrodynamic mass, quadratic drag, righting moment, and buoyancy parameters) that enter linearly into 6 degree-of-freedom (6-DOF) second-order rigid-body UV plant dynamic models. The reported UV AID method does not require instrumentation of vehicle acceleration as is required of other standard plant parameter identification methods such as conventional least squares. All but one previously reported adaptive methods for second-order nonlinear plants have addressed the problem of model-based adaptive tracking control—approaches in which adaptive plant model identification is performed simultaneously with model-based trajectory-tracking control of fully-actuated second-order plants; however, these approaches are not applicable when the plant is either uncontrolled, under open-loop control, underactuated, or using any control law other than an algorithm-specific adaptive tracking controller. The UV AID algorithm reported herein does not require simultaneous reference trajectory-tracking control, nor does it require instrumentation of linear acceleration or angular acceleration; thus this novel approach complements previously reported adaptive tracking methods and is applicable to a broader class of UV applications for which fully-actuated tracking control is impractical or infeasible. We report a experimental performance analysis of the UV AID algorithm in comparison to conventional least-square identification methods, including comparison in cross-validation where the performance of the experimentally identified plant models obtained in identification trials are compared to experimental trials differing from the identification trials.     

Circumferential-Slot Virtual Impactors with Stable Flow

Flow instabilities in a virtual impactor designed for bioaerosol concentration (size range about 2 to 10 μ m AD) can seriously degrade performance. When the flow in a 100 L/min circumferential slot virtual impactor (CSVI) was unstable, the transmission efficiency was 30% for 7.2 μ m AD aerosol particles, but when the instability problems were corrected, the transmission efficiency was increased to above 90%. Three-dimensional CFD simulations have been used to examine flows in two CSVIs, a nominal 10 L/min device in which the flow was stable, and the 100 L/min device in which the flow was initially unstable. From the CFD flow patterns in the 100 L/min device, the principal instability was in the minor flow region and was caused by overly rapid flow deceleration, too large of a volume, and too low of a jet velocity in that region. Changes were made to the geometry of the CSVI, and CFD was used as the diagnostic tool to determine when stable flow was achieved. Also, for the 100 L/min unit, wake effects from alignment posts that hold together the two halves of the CSVI propagated into the receiver section, and CFD analyses were used to modify the post locations to optimize the transmission efficiencies for the stable units. Numerical and experimental results show the dynamic ranges (ratio of the largest Stokes number for which the transmission efficiency is 50% to the cutpoint Stokes number) are about 100 for both devices. The peak value of the transmission efficiency for the 100 L/min unit is 95% and that for the 10 L/min device is 97%.     

Aerosol-to-Hydrosol Transfer Stages for Use in Bioaerosol Sampling

Single-jet and multijet aerosol-to-hydrosol transfer stages (AHTSs) with cutpoints of 2 and 0.8 μm aerodynamic diameter, respectively, were designed and evaluated. The devices are intended to take the coarse particle flow stream (minor flow) from a virtual impactor and concentrate the aerosol particles into a low flow rate of liquid. The design air flow rate for each system is 1 L/min, and the collection liquid flow needs to be ≥ 0.3 mL/min with a surfactant added to prevent loss of hydrosol particles on internal surfaces of the devices. Satisfactory performance was achieved when distilled water with 0.1% Tween 20 was used as the collection fluid. The effectiveness (average fractional efficiency) for the single-jet device is 94% over the size range of 2.5 to 10 μ m aerodynamic diameter, and that of the multijet AHTSs is 90% over the size range of 1 to 10 μ m aerodynamic diameter. The systems have an ideal air power consumption of 1.4 mW and 4.5 mW, respectively. If an AHTS were operated in a heated enclosure and sampled air at ?28°C, less than 1 W of heating would be required to prevent freezing. Preliminary results of bioaerosol testing with 0.7 μm AD single spores of Bacillus globigii var. niger show efficiencies over 100%. These values are probably due to the different expression of viability of the spores in the reference samples and those in the output liquid of the AHTSs.     

Effects of shell crosslinking on polyurea microcapsules containing a free‐radical initiator

Microencapsulation of a material is often used when a controlled release of a substance is desired. This study examines the effects of crosslinking in polyurea microcapsule shells on stability of microcapsules containing the free‐radical initiator cumene hydroperoxide (CHP). Crosslinking of polyurea shells was varied by using amine monomers containing different amine functionalities, and/or changing the isocyanate/primary amine ratio. Thermogravimetric analysis was performed to determine thermal properties of these microcapsules, and the pot lives of monomer systems containing these microcapsules were measured. Thermal stability is greater with a moderate degree of crosslinking from a trifunctional amine, and decreases when crosslinking is increased through use of higher amine functionality. Stability in monomer media generally increases with increased crosslinking through higher amine functionality, but is less predictable due to crosslinks formed between capsules. Generally, increasing crosslinking through altering the isocyanate to primary amine ratio decreases capsule stability in both dry and monomer storage. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42408.