Can the absence of prejudice be more threatening than its presence? It depends on one's worldview.

The present research used validated cardiovascular measures to examine threat reactions among members of stigmatized groups when interacting with members of nonstigmatized groups who were, or were not, prejudiced against their group. The authors hypothesized that people's beliefs about the fairness of the status system would moderate their experience of threat during intergroup interactions. The authors predicted that for members of stigmatized groups who believe the status system is fair, interacting with a prejudiced partner, compared with interacting with an unprejudiced partner, would disconfirm their worldview and result in greater threat. In contrast, the authors predicted that for members of stigmatized groups who believe the system is unfair, interacting with a prejudiced partner, compared with interacting with an unprejudiced partner, would confirm their worldview and result in less threat. The authors examined these predictions among Latinas interacting with a White female confederate (Study 1) and White females interacting with a White male confederate (Study 2). As predicted, people's beliefs about the fairness of the status system moderated their experiences of threat during intergroup interactions, indicated both by cardiovascular responses and nonverbal behavior. The specific pattern of the moderation differed across the 2 studies. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Increased Airborne Bacterial Survival as a Function of Particle Content and Size

ABSTRACT

Two test vegetative bacteria, Pseudomonas syringae and Erwinia herbicola, and a physical aerosol decay indicator, Bacillus subtilis var. niger spores, were sprayed into a particle size fractionating wind tunnel. Test bacterial survival significantly increased directly with droplet size for varying test cell to spore ratios and temperature. However, survival varied inversely with relative humidity.     

Intact implicit memory for newly formed verbal associations in amnesic patients following single study trials.

This study examines the ability of amnesic patients to recover newly formed associations implicitly after a single study trial. Fifteen amnesic patients with various etiologies studied pairs by forming a sentence containing both words. At test, all participants saw 40 intact pairs, 40 rearranged pairs, and 40 new words. All pairs appeared side by side both at study and at test. For the implicit lexical-decision task, 40 nonwords were intermixed with the other pairs, and participants indicated whether both items were words. For the explicit speeded recognition test, participants were asked to indicate whether both words had appeared at study. Despite being severely impaired on the explicit test, amnesic patients performed like healthy controls on the implicit test, with faster and more accurate responses to intact pairs than to recombined pairs. Contrary to existing theories, the results suggest that amnesic patients can form and retain new associations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Associations between age,gender, psychosocial and health characteristics in the Candrive II study cohort

The relations among driving-related psychosocial measures (e.g., driving comfort, attitudes toward driving) and measures of self-reported health were examined in the context of driver characteristics (i.e., age and gender) within the Canadian Driving Research Initiative for Vehicular Safety in the Elderly (Candrive II) baseline data, available for the cohort of 928 drivers, 70 years of age and older. Older members of the cohort had lower comfort scores and poorer perceptions of their driving abilities. Men reported significantly higher levels of driving comfort than women. When analyses including health were controlled for age and gender, significant relations with health status were evident for most of the psychosocial measures. These findings extend previous research and suggest that attitudes, beliefs, and perceptions about driving may be influenced by health status and act as mediators in the self-regulation process.     

Scale‐up of agitated drying: Effect of shear stress and hydrostatic pressure on active pharmaceutical ingredient powder properties

Scale‐up of agitated drying processes to minimize particle size changes in active pharmaceutical ingredients (API) can be challenging. Particle agglomeration or attrition problems due to agitated drying are often discovered on the initial scale‐up from the lab to the plant. Traditional laboratory drying equipment has not successfully reproduced the degree of agglomeration or attrition observed at scale. This discrepancy may be attributed to the ability of particulate solids, such as crystalline API's to transfer stresses from the normal direction into the shearing direction. As batch size increases during scale‐up, the compressive and shearing forces experienced by the API increase. To overcome this limitation, a modified laboratory setup was constructed which reproduces the range of hydrostatic pressures observed during scale‐up. This work highlights the use of the modified setup to characterize the propensity for particle attrition to occur at different stages of the drying process by measuring impeller torque. Torque measurements of the API powder at different hydrostatic pressures revealed a behavior consistent with Coulomb's law of friction. The torque data obtained from these measurements were used to determine the bulk friction coefficient for API powder beds at different liquid content. Additionally, the amount of work done by the impeller blades was correlated to the degree of particle attrition observed. A workflow for assessing risk of API attrition at scale is described. © 2014 American Institute of Chemical Engineers AIChE J, 61: 407–418, 2015     

Experiments and simulations of cohesionless particles with varying roughness in a bladed mixer

The kinematics of granular flow of cohesionless particles in a bladed mixer was studied experimentally using particle image velocimetry and computationally using the discrete element method. The discrete element simulations were able to reproduce the surface velocities, granular temperature profiles, and mixing kinetics observed experimentally. Procedures for roughening of glass bead surfaces via coating were developed and the effect of surface roughness was studied experimentally and computationally. Increasing particle surface roughness led to the development of less uniform flows inside the mixer and to increased dilation of the particle bed. Systems composed of rougher particles experienced increased radial and vertical velocities as well as higher particle diffusivities. Cylinder wall roughness was also shown to significantly influence particle velocities in bladed mixers. Rough cylinder walls led to more pronounced particle velocity fluctuations near the top surface and to an increase in granular temperature. The effect of increasing blade speed was also studied. Two distinct flow regimes were observed as blade speed was increased. At low rotational speed, the flow occurs in the bumping regime where particle surface velocities are linearly proportional to the tip speed of the blades. In this regime, the rotational speed of the blades provides the time scale for momentum transfer and for the mixing process. At higher rotational speed, the roping regime is encountered where particle surface velocities are no longer proportional to the tip speed of the blades. This regime is characterized by enhanced radial and vertical particle velocities as well as faster mixing kinetics.     

Sequence-independent helical wrapping of single-walled carbon nanotubes by long genomic DNA

Because of their nanometer sizes and molecular recognition capabilities, biological systems have garnered much attention as vehicles for the directed assembly of nanoscale materials.(1-6) One of the greatest challenges of this research has been to successfully interface biological systems with electronic materials, such as semiconductors and metals. As a means to address some of these issues, Sarikaya, Belcher, and others have used a combinatorial technique called phage display(7-9) to discover new families of peptides that showed binding affinities to various substrates. More recently, Zheng and co-workers used combinatorial DNA libraries to isolate short DNA oligomers (30-90 bases) that could disperse single-walled carbon nanotubes (SWCNT) in water.(10) Through a systematic analysis, they found that short oligonucleotides having repeating sequences of gunanines and thymines (dGdT)(n) could wrap in a helical manner around a CNT with periodic pitch.(11) Although helix formation around SWCNTs having regular pitches is an effective method for dispersing and separating CNTs, the need for specific repeating sequences limits use to non-natural DNA that must be synthesized with optimal lengths of less than 150 bases. In contrast, we demonstrate here that long genomic single-stranded DNA (>100 bases) of a completely random sequence of bases can be used to disperse CNTs efficiently through the single-stranded DNA's (ssDNA) ability to form tight helices around the CNTs with distinct periodic pitches. Although this process occurs irrespective of the DNA sequence, we show that this process is highly dependent on the removal of complementary strands. We also demonstrate that although the helix pitch-to-pitch distances remain constant down the length of a single CNT, the distances are variable from one DNA-CNT to another. Finally, we report initial work that shows that methods developed to align long dsDNA can be applied in a similar fashion to produce highly dense arrays of aligned ssDNA-CNT hybrids.     

A field study of the microbiological quality of fresh produce of domestic and Mexican origin

Produce is responsible for an increasingly larger proportion of foodborne disease outbreaks. In particular, the globalization of the food supply may introduce new food safety risks and allow widespread distribution of contaminated food, particularly produce. The objectives of this study were to: (i) compare the overall quality of domestic and Mexican produce throughout the packing process; (ii) examine changes in microbiological quality of both domestic and Mexican produce at each stage of production and processing; and (iii) evaluate the prevalence of select pathogens on fresh produce, including leafy green, herbs, melons, and vegetables. Furthermore, we also sought to characterize the antibiotic resistance profiles of Enterococcus faecium and Enterococcus faecalis strains isolated from fresh produce. A total of 466 produce and matching environmental swab samples was collected from various locations in packing sheds in the southern US from November 2002 through December 2003. These samples were assayed by enumerative tests for total aerobic bacteria (APC), total coliforms, total Enterococcus, and E. coli. Produce samples were also analyzed for the presence of Salmonella, Listeria monocytogenes, Shigella, and E. coli O157:H7. A total of 112 E. faecium and E. faecalis isolates were further screened for antibiotic resistance using a panel of seventeen antibiotics. Overall, the microbiological quality of fresh produce ranged from 4.0 to 7.9 log(10) CFU/g (APC); less than 1.0 log(10) to 4.5 log(10) CFU/g (coliforms); less than 1.0 log(10) to 4.0 log(10) CFU/g (E. coli); and less than 1.0 log(10) to 5.4 log(10) CFU/g (Enterococcus). No Salmonella, Shigella, or E. coli O157:H7 were detected from the 466 25-g produce samples tested. However, three domestic cabbage samples were found to be positive for L. monocytogenes. Of the Enterococcus isolates, E. faecium had a higher degree of resistance to antibiotics in general, while Enterococcus spp. isolated from Mexican produce had a higher degree of antibiotic resistance when compared to strains isolated from produce samples of domestic origin. Despite increased attention to the role of imported produce in foodborne disease, this study does not support the assumption that domestic produce is of higher microbial quality than Mexican produce.     

Optical properties of Cl-doped ZnSe epilayers grown on GaAs substrates

We have determined the optical properties of a series of Cl-doped ZnSe epilayers grown on GaAs substrates using ellipsometry and prism coupling. Initially, the carrier concentrations were determined using Hall measurements for samples between 6.30×10¹⁶ cm⁻³ and 9.50×10¹⁸ cm⁻³. Using a variable angle spectroscopic ellipsometer in the energy range between 0.7 eV and 6.5 eV, we then obtained experimental spectra for each of the samples. By incorporating a three-layer model to simulate the experimental data, we determined the complex dielectric functions for these Cl-doped ZnSe epilayers. In order to facilitate this modeling procedure, we have complemented the ellipsometric results with prism coupling experiments that measured the film thickness and the index of refraction (at discrete wavelengths) very precisely. For the fundamental band gap, we observe a blue shift with respect to the doping concentration, which can be explained by the Burstein-Moss effect. In addition, we have determined the critical point parameters related to these specimens by fitting the second derivatives of both the real and the imaginary parts of the dielectric functions. Similar to several doped III-V semiconductors reported thus far, we find that in Cl-doped ZnSe epilayers, both E₁ and E₁ + Δ ₁ red shift, as well as a broadening with respect to the doping concentration.