Kevin S. McCarter

Geographic, seasonal, and precipitation chemistry influence on the abundance and activity of biological ice nucleators in rain and snow

Biological ice nucleators (IN) function as catalysts for freezing at relatively warm temperatures (warmer than −10 °C). We examined the concentration (per volume of liquid) and nature of IN in precipitation collected from Montana and Louisiana, the Alps and Pyrenees (France), Ross Island (Antarctica), and Yukon (Canada). The temperature of detectable ice-nucleating activity for more than half of the samples was ≥ −5 °C based on immersion freezing testing. Digestion of the samples with lysozyme (i.e., to hydrolyze bacterial cell walls) led to reductions in the frequency of freezing (0–100%); heat treatment greatly reduced (95% average) or completely eliminated ice nucleation at the measured conditions in every sample. These behaviors were consistent with the activity being bacterial and/or proteinaceous in origin. Statistical analysis revealed seasonal similarities between warm-temperature ice-nucleating activities in snow samples collected over 7 months in Montana. Multiple regression was used to construct models with biogeochemical data [major ions, total organic carbon (TOC), particle, and cell concentration] that were accurate in predicting the concentration of microbial cells and biological IN in precipitation based on the concentration of TOC, Ca2+, and NH4+, or TOC, cells, Ca2+, NH4+, K+, PO43−, SO42−, Cl−, and HCO3−. Our results indicate that biological IN are ubiquitous in precipitation and that for some geographic locations the activity and concentration of these particles is related to the season and precipitation chemistry. Thus, our research suggests that biological IN are widespread in the atmosphere and may affect meteorological processes that lead to precipitation.

Ionic liquid-based optoelectronic sensor arrays for chemical detection

Development of ionic liquid (IL)-based colorimetric sensor arrays for detection and identification of chemicals in both the aqueous and vapor phases is reported. These facile and inexpensive optoelectronic sensors were fabricated by using ionic liquids (ILs) derived from readily available pH indicator dyes. A series of 12 different chemosensory ILs were synthesized by pairing anionic pH indicator dyes with trihexyl(tetradecyl)phosphonium ([P66614]) cation via an ion exchange reaction. The incorporation of the [P66614] cation imparted hydrophobic characteristics to these ILs, and this induced hydrophobicity led to their desired low solubility in aqueous solutions, as well as eliminated the need for a specialized hydrophobic matrix/substrate for immobilization. In this manuscript, four different matrices, i.e. glass microfiber filter papers, cotton threads, silica thin layer chromatography (TLC) plates, and alumina TLC plates, were employed for fabrication of sensor arrays. These sensor arrays were used to analyze pH values of aqueous solutions as well as for detection of acidic and basic vapors. To further prove the applicability of these IL sensor arrays as tools to sense closely related complex materials, the arrays were applied to successful discrimination of aqueous solutions of smoke from three commercially available cigarettes. The digital data generated from these sensor arrays were used in developing predictive models for accurately identifying various analytes. Two approaches were used for developing the models, and two methods were applied for assessing the predictive accuracy of the models. Use of cotton threads as a matrix led to development of a more flexible, low volume, and lightweight array to estimate pH and detect a variety of vapors. These wearable arrays may possibly be incorporated into bandages, sweatbands, diapers, and similar systems. Overall, these IL-based sensor arrays should provide a new research direction in the development of advanced colorimetric sensor arrays for detection and identification of a range of analytes relevant to many different applications.

Virtual Colorimetric Sensor Array: Single Ionic Liquid for Solvent Discrimination

There is a continuing need to develop high-performance sensors for monitoring organic solvents, primarily due to the environmental impact of such compounds. In this regard, colorimetric sensors have been a subject of intense research for such applications. Herein, we report a unique virtual colorimetric sensor array based on a single ionic liquid (IL) for accurate detection and identification of similar organic solvents and mixtures of such solvents. In this study, we employ eight alcohols and seven binary mixtures of ethanol and methanol as analytes to provide a stringent test for assessing the capabilities of this array. The UV-visible spectra of alcoholic solutions of the IL used in this study show two absorption bands. Interestingly, the ratio of absorbance for these two bands is found to be extremely sensitive to alcohol polarity. A virtual sensor array is created by using four different concentrations of IL sensor, which allowed identification of these analytes with 96.4-100% accuracy. Overall, this virtual sensor array is found to be very promising for discrimination of closely related organic solvents.

Comparison of the Validity of Four Fall-Related Psychological Measures in a Community-Based Falls Risk Screening

Abstract We examined the measurement properties of fall-related psychological instruments with a sample of 133 older adults (M age = 74.4 years, SD = 9.4). Measures included the Comprehensive Falls Risk Screening Instrument, Falls-efficacy Scale-International (FES-I), Activities-specific Balance Confidence (ABC), modified Survey of Activities and Fear of Falling in the Elderly (mSAFFE), Consequences of Falling (CoF), Physical Activity Scale for the Elderly (PASE), and 36-Item Short-Form Health Survey (SF-36). The FES-I, ABC, mSAFFE, and CoF were significantly correlated with each other, with SF-36, and with mobility. The ABC and mSAFFE were significantly correlated with PASE. The ABC differentiated between fallers and nonfallers and predicted total falls risk. Findings can assist with the selection of psychological instruments in a falls risk screening context.

Calcium promotes exopolysaccharide phase variation and biofilm formation of the resulting phase variants in the human pathogen Vibrio vulnificus

Vibrio vulnificus is a Gram-negative bacterium found in estuaries and coastal waters and is associated with human disease caused by ingestion of raw shellfish. Pathogenesis is directly related to the presence of capsular polysaccharide (CPS). Encapsulated virulent strains exhibit an opaque colony phenotype, while unencapsulated attenuated strains appear translucent. A third colony type, rugose, is caused by expression of rugose extracellular polysaccharide (rEPS) and forms robust biofilms. Vibrio vulnificus undergoes phase variation associated with altered levels of CPS and rEPS, and we show here that calcium (Ca²(+) ) significantly increases the rate of CPS and rEPS phase variation in this species. Interestingly, multiple phenotypic responses to increased [Ca²(+) ] were observed among strains, which suggests the existence of underlying cognate genetic or epigenetic differences. Certain translucent isolates contained deletions at the group I CPS operon, inferring increased [Ca²(+) ] upregulates existing phase variation mechanisms. Expanding on a previous observation (Kierek and Watnick, Proc. Natl. Acad. Sci. USA 100: 14357-14362, 2003), increased [Ca²(+) ] also enhanced biofilm formation for all phase variants. Our results show that Ca²(+) promotes both polysaccharide phase variation and biofilm formation of the resulting phase variants, thereby likely serving a dual role in persistence of V. vulnificus in the environment.

Development and Validation of the Comprehensive Falls Risk Screening Instrument

ABSTRACT Annually, one in three older adults experiences a fall. Falls can lead to death, disability, and/or decreased health-related quality of life (HRQL). Objectives: To validate the Comprehensive Falls Risk Screening Instrument (CFRSI). Methods: Data were collected on 286 older adults (M age in years = 74.2 ± 10.0). The CFRSI total falls risk score was compared to subscale scores, the Physical Activity Scale for the Elderly (PASE), the Functional Status Index (FSI), and HRQL (SF-36, PCS, and Mental Component Summary (MCS)) scores. Results: The total CFRSI falls risk score was associated with all subscales (r = 0.25, p < 0.01 to r = 0.69, p < 0.01), PASE (r = −0.30, p < 0.01), FSI (r = 0.30, p < 0.01), and SF-36 PCS and MCS scores (r = −0.44, p < 0.01 to r = −0.24, p = 0.03, respectively). Fallers (n = 90) had a higher total falls risk score (M = 41.03 ± 9.38) than nonfallers (n = 188, M = 34.06 ± 10.05, t [276] = 5.53, p < 0.001). The most important predictor of falling status was only the history risk score (r = 0.96). Strong association of variables supports the construct validation of the CFRSI. The CFRSI is a valid comprehensive measure of falls risk that allows for identification of older adults who are at risk for falls and the specific areas that should be targeted for falls prevention.

The Relationship Between Content Area General Outcome Measurement and Statewide Testing in Sixth-Grade World History:

The purpose of the present study was to extend validity research on a content area general outcome measurement tool known as vocabulary matching. Previous research has reported moderately strong to strong correlations between the group-administered vocabulary-matching measure and a standardized assessment instrument. The present study extended the validity research to a statewide accountability assessment. A diverse sample of 146 sixth-grade students from a rural middle school were administered three vocabulary-matching probes and the sixth-grade iLEAP (integrated Louisiana Educational Achievement Program) social studies criterion-referenced test at different times. Strong correlations were reported between the two measures. Moreover, vocabulary-matching achievement patterns with respect to gender, ethnicity, socioeconomic status, and exceptionality status were similar to those of the iLEAP. Alternate-form reliability correlations between the three probes were also strong. Research implications, limitations, and future directions are discussed.

Examining an Online Content General Outcome Measure: Technical Features of the Static Score

The purpose of this study was to evaluate technical adequacy features of an online adaptation of vocabulary matching known as critical content monitoring. Validity and reliability studies were conducted with a sample of 106 students from one school in fifth-grade science content. Participants were administered 20 parallel forms of the general outcome measure over a 2-week period. Criterion-related validity correlations with a statewide accountability test ranged from .36 to .55 for the 20 parallel forms. A pooled estimate of a common correlation between the state test and the probes was found to be .45. While correlation differences were not found, statistically significant differences in probe mean scores were identified across the body of parallel forms. Student commentary regarding the online assessment process was largely positive. Alternate-form reliability correlations ranged from .21 to .73, with a median correlation of .56. Limitations and implications are addressed.

Designing experiments to evaluate the effectiveness of precision agricultural practices on research fields: part 1 concepts for their formulation

A better method is needed to evaluate the effectiveness of precision agricultural practices on research farm fields. We present a novel methodology for formulating the design of an experiment to evaluate the effectiveness of precision agricultural practices. The method combines a georeferenced treatment structure and a georeferenced design structure to build a mixed model that describes and analyzes the site-specific experiment. One or more layers of georeferenced information (obtained by various remote-sensing systems) describing the topography of the research field and its crop attributes may be included as covariates in the mixed model. The concepts of this approach are illustrated through the use of a hypothetical field. Current limitations are also discussed.

Post and During Event Effect of Cell Phone Talking and Texting on Driving Performance—A Driving Simulator Study

Objective: A number of studies have been done in the field of driver distraction, specifically on the use of cell phone for either conversation or texting while driving. Researchers have focused on the driving performance of drivers when they were actually engaged in the task; that is, during the texting or phone conversation event. However, it is still unknown whether the impact of cell phone usages ceases immediately after the end of task. The primary objective of this article is to analyze the post-event effect of cell phone usage (texting and conversation) in order to verify whether the distracting effect lingers after the actual event has ceased. Methods: This study utilizes a driving simulator study of 36 participants to test whether a significant decrease in driver performance occurs during cell phone usage and after usage. Surrogate measures used to represent lateral and longitudinal control of the vehicle were standard deviation (SD) of lane position and mean velocity, respectively. Results: Results suggest that there was no significant decrease in driver performance (both lateral and longitudinal control) during and after the cell phone conversation. For the texting event, there were significant decreases in driver performance in both the longitudinal and lateral control of the vehicle during the actual texting task. The diminished longitudinal control ceased immediately after the texting event but the diminished lateral control lingered for an average of 3.38 s. The number of text messages exchanged did not affect the magnitude or duration of the diminished lateral control. Conclusion: The result indicates that the distraction and subsequent elevated crash risk of texting while driving linger even after the texting event has ceased. This finding has safety and policy implications in reducing distracted driving.