Showing papers by "Mississippi State University published in 1999"

Level of automation effects on performance, situation awareness and workload in a dynamic control task

Abstract: Various levels of automation (LOA) designating the degree of human operator and computer control were explored within the context of a dynamic control task as a means of improving overall human/machine performance. Automated systems have traditionally been explored as binary function allocations; either the human or the machine is assigned to a given task. More recently, intermediary levels of automation have been discussed as a means of maintaining operator involvement in system performance, leading to improvements in situation awareness and reductions in out-of-the-loop performance problems. A LOA taxonomy applicable to a wide range of psychomotor and cognitive tasks is presented here. The taxonomy comprises various schemes of generic control system function allocations. The functions allocated to a human operator and/or computer included monitoring displays, generating processing options, selecting an 'optimal' option and implementing that option. The impact of the LOA taxonomy was assessed within a dynamic and complex cognitive control task by measuring its effect on human/system performance, situation awareness and workload. Thirty subjects performed simulation trials involving various levels of automation. Several automation failures occurred and out-of-the-loop performance decrements were assessed. Results suggest that, in terms of performance, human operators benefit most from automation of the implementation portion of the task, but only under normal operating conditions; in contrast, removal of the operator from task implementation is detrimental to performance recovery if the automated system fails. Joint human/system option generation significantly degraded performance in comparison to human or automated option generation alone. Lower operator workload and higher situation awareness were observed under automation of the decision making portion of the task (i.e. selection of options), although human/system performance was only slightly improved. The implications of these findings for the design of automated systems are discussed.

Global dynamics of a SEIR model with varying total population size.

Abstract: A SEIR model for the transmission of an infectious disease that spreads in a population through direct contact of the hosts is studied The force of infection is of proportionate mixing type A threshold sigma is identified which determines the outcome of the disease; if sigma 1, the infected fraction persists and a unique endemic equilibrium state is shown, under a mild restriction on the parameters, to be globally asymptotically stable in the interior of the feasible region Two other threshold parameters sigma' and sigma are also identified; they determine the dynamics of the population sizes in the cases when the disease dies out and when it is endemic, respectively

The Modified Delphi Technique - A Rotational Modification

Abstract: This study describes and illustrates a modification of the Delphi technique that was designed to extend its applicability to large competency data sets The approach consisted of rotating sub-sets of a larger set of competencies through three sub-panels and then examining the viability of the approach The context of the study was the identification of competencies needed to update training requirements for 21st century plastering contractors Based on the outcomes of this study, the rotational approach represents a promising mechanism for extending the usefulness of the Delphi tool to larger data sets The findings also indicate that the factors that erode the validity and usefulness of traditional modified Delphi studies also negatively affect the rotational approach An obstacle facing many educators has been identifying an appropriate research methodology for developing curriculum when teaching vocational subjects This is especially true when a research topic is very broad and when new curricular areas are being developed In such situations there is often a large number of competencies to be evaluated by recognized experts in the content area A number of techniques have been used that are generally associated with the competency-based approach to curriculum development These include such tools as occupational analysis, DACUM (Developing a Curriculum), and the Delphi technique ( Finch & Crunkilton, 1989 ; Frykland, 1970 ; Miller, 1990 ; Rothwell & Kazanas, 1992 ) These techniques span a range of approaches from observing workers on the job to conducting meetings with workers to conducting analyses based on work previously conducted on related occupations ( Blank, 1982 ) Each technique has advantages and disadvantages, especially in dealing with diverse groups of experts involving relatively large data sets This manuscript describes a modification developed for use with the Delphi technique, which was selected for use in a curriculum competency study The Delphi technique was selected for use in this study due to its ability to obtain expert input from individuals who were widely dispersed geographically This technique has been used in a number of fields for long-range planning - including education, international affairs, transportation, leisure activities and the like ( McCampbell & Stewart, 1992 ) The Delphi survey technique was developed in the 1950s by two research scientists working at The Rand Corporation, Olaf Helmer and Norman Dalkey They developed the procedure as a tool for forecasting future events using a series of intensive questionnaires interspersed with controlled-opinion feedback ( Dalkey & Helmer,1993 ; McCampbell & Stewart, 1992 ; Weaver, 1971 ) Participants were solicited experts in the issues related to national defense such as forecasting probable bombing targets the Russian government might choose in the event of an attack on the United States ( Dalkey & Helmer, 1963 ) The Delphi begins with an open-ended questionnaire that is given to a panel of selected experts to solicit specific information about a subject or content area In subsequent rounds of the procedure, participants rate the relative importance of individual items and also make changes to the phrasing or substance of the items Through a series of rounds (typically three) the process is designed to yield consensus The modified Delphi technique is similar to the full Delphi in terms of procedure (ie, a series of rounds with selected experts) and intent (ie, to predict future events and to arrive at consensus) The major modification consists of beginning the process with a set of carefully selected items These pre-selected items may be drawn from various sources including related competency profiles, synthesized reviews of the literature, and interviews with selected content experts The primary advantages of this modification to the Delphi is that it (a) typically improves the initial round response rate, and (b) provides a solid grounding in previously developed work Additional advantages related to the use of the modified Delphi technique include reducing the effects of bias due to group interaction, assuring anonymity, and providing controlled feedback to participants ( Dalkey 1972a, 1972b, & Judd 1972 ) Brooks (1979) noted that three mailings are usually sufficient in order to arrive at consensus

An examination of perceived risk, information search and behavioral intentions in search, experience and credence services

Abstract: Though the marketing literature offers an abundance of research on the topics of perceived risk, information search, and purchase intentions, very few researchers have empirically examined these constructs in the context of services. This research explores the linkages among these three constructs when services are classified on the basis of search, experience, and credence attributes. Specific hypotheses are developed and tested. The results of this study indicate that perceived risk increases along a continuum from search to experience to credence service purchases. Other hypotheses relating to information search length, information sources, behavioral intentions, and service attributes, received moderate support. Finally, managerial implications of the study were provided, along with directions for future research.

The Fourth BATSE Gamma-Ray Burst Catalog (Revised)

Abstract: The Burst and Transient Source Experiment (BATSE) on the Compton Gamma Ray Observatory (CGRO) has triggered on 1637 cosmic gamma-ray bursts between 1991 April 19 and 1996 August 29. These events constitute the Fourth BATSE burst catalog. The current version (4Br) has been revised from the version first circulated on CD-ROM in 1997 September (4B) to include improved locations for a subset of bursts that have been reprocessed using additional data. A significant difference from previous BATSE catalogs is the inclusion of bursts from periods when the trigger energy range differed from the nominal 50-300 keV. We present tables of the burst occurrence times, locations, peak fluxes, fluences, and durations. In general, results from previous BATSE catalogs are confirmed here with greater statistical significance.

A revealed preference study of management journals' direct influences

Abstract: Our study develops and uses a new methodology for analyzing journal citations to recent publications to determine which management journals now have the greatest influence on the field of management. It analyzes the 23637 academic journal references cited in the 1275 articles published in 17 key management journals during 1993 and 1994, focusing on citations to references published up to the modal vintage of 4 years earlier. Most cited as a percentage of all these references was Strategic Management Journal (11%), followed by Academy of Management Journal, Journal of Applied Psychology, Organizational Behavior and Human Decision Processes, Academy of Management Review, Administrative Sciences Quarterly, and Journal of Management—accounting in total for 51 percent of all citations. Strategic Management Journal, whose subfield of strategic management has become a major concern of management in general, has developed as the predominant academic journal influencing the field of management. Our measures of journal influence provide information which can aid management scholars, practitioners, department heads, and university libraries to decide on efficient choices of journals for research and for manuscript submissions, for evaluation, and for subscriptions. Just seven management and social science journals, led by Strategic Management Journal, contain more than half of the cited articles published recently. Copyright © 1999 John Wiley & Sons, Ltd.

Constructivism: The Career and Technical Education Perspective

Abstract: For over three-quarters of a century, the implicit learning theory underlying the curriculum and pedagogy of career and technical education has been behaviorism, but the emerging theory of constructivism may have implications for career and technical education practice in the future. Preparation of workers for entry into and advancement in the workplace of the next decade requires an educational program that provides not only job skills, as career and technical education did throughout the 1900s, but also higher order thinking, problem solving, and collaborative work skills. Classical behaviorist theory does not adequately address the latter kinds of learning, but constructivist theory may. Constructivist principles are examined in light of the fundamental requirements of career and technical education as we move into the new century with a new name for a redesigned profession. Of the three basic types of constructivism discussed, cognitive constructivism is most compatible with career and technical education. The authors recommend a more thorough examination of the relative efficacy of behaviorism and cognitive constructivism to serve as the learning theory on which to base career and technical education in the future. To embrace such a foundational change, leaders in the profession must re-think many of the fundamental assumptions underlying the mission, curriculum, and pedagogy of career and technical education. Perhaps such a rethinking is due.

Impoundments and the decline of freshwater mussels : A case study of an extinction gradient

Abstract: One major factor leading to the imperilment of freshwater mussels (Bivalvia, Unionidae) has been the large-scale impoundment of rivers. We examined the distribution and abundance of mussels at 37 sites along a 240-km length of the Little River in southeastern Oklahoma, U.S.A., which is affected by both main- stem and tributary reservoirs. We observed a mussel extinction gradient downstream from impoundments in this river: with increasing distance from the mainstem reservoir there was a gradual, linear increase in mus- sel species richness and abundance. Mussel species distributions were significantly nested, with only sites fur- thest from the impoundment containing relatively rare species. Below the confluence with the inflow from the second reservoir these same trends were apparent but much weaker, and overall mussel abundance was greatly reduced. Our results suggest that considerable stream lengths are necessary to overcome the effects of impoundment on mussel populations, and such information should be considered in conservation and man- agement plans.

Are There Religious Variations in Domestic Violence

Abstract: Religious variations in domestic violence remain understudied. Arguments are developed linking aspects of religious affiliation, practice, theology, and couples' religious (dis)similarities with domestic violence. These relationships are then examined via gender-specific models of data from the first wave of the National Survey of Families and Households (NSFH-1). The authors find that regular attendance at religious services is inversely associated with self-reported perpetration of domestic violence for men and women. Denominational homogamy (i.e., same-faith vs. mixed-faith relationships) has little bearing on the likelihood of abuse. Other forms of religious dissimilarity do appear to heighten the risk of abuse. In particular, men who hold much more conservative theological views than their partners are especially likely to perpetrate domestic violence. The implications of these and other findings are discussed, and several promising directions for further research are identified.

Variation in Susceptibility of Noctuid (Lepidoptera) Larvae Attacking Cotton and Soybean to Purified Endotoxin Proteins and Commercial Formulations of Bacillus thuringiensis

Abstract: Susceptibility of Heliothis virescens (F.), Helicoverpa zea (Boddie), Pseudoplusia includens (Walker), Spodoptera exigua (Hubner), and Spodoptera frugiperda (J. E. Smith) to purified endotoxins and commercial formulations of Bacillus thuringiensis Berliner was measured in a wide range of colonies collected from 8 states in the U.S. Cotton Belt during 1992 and 1993. Results indicated that field-collected colonies of H. virescens, H. zea, P. includens, and S. frugiperda were as susceptible as laboratory-reared colonies and those reported in the literature to the purified endotoxin proteins Cry1Ac and Cry1Ab or the commercial formulations Javelin WG, Dipel ES, and Condor OF in diet-treated assays. Colonies of S. exigua collected from transgenic cotton expressing endotoxin protein had elevated median lethal concentrations (LC50s) compared with a colony collected from nontransgenic cotton or those from laboratory colonies. Ranges of LC50s for field-collected colonies of H. virescens generally were similar to the ranges observed for laboratory colonies and similar to those reported in the literature. Wider ranges of variation in LC50s were observed among populations of H. zea and S. exigua than among populations of the other species. However, the highest LC50 observed for H. zea was no higher than those reported in the literature. Only a few colonies of P. includens and S. exigua were tested. P. includens susceptibility was generally greater than that of H. virescens and less than that of H. zea. S. frugiperda was the least susceptible species studied. Variability in LC50s obtained with Cry1Ac ( r = 0.702) correlated with variability in LC50s for Cry1Ab across 13 colonies of H. virescens exposed to both proteins. Colonies of H. zea and H. virescens were pooled into single colonies and selected with the insecticidal proteins to produce endotoxin-resistant strains. Selection for resistance in H. virescens was not successful, but a strain of H. zea was selected that had elevated LC50s (10 times) after 2 generations and very high LC50s compared with a susceptible laboratory strain (100 times) after 8 generations, suggesting that H. zea has the genetic capacity to develop resistance to endotoxin proteins.

Vapor grown carbon fiber composites with epoxy and poly(phenylene sulfide) matrices

Abstract: Vapor grown carbon fibers (VGCF, Pyrograf III™ from Applied Sciences, Inc.), with 100–300 nm diameters and ∽10–100 μm lengths, were formulated in various fiber volume fractions into epoxy (thermoset) and into poly(phenylene sulfide) (thermoplastic) composites. Increases in stiffness were observed as with previous VGCF/organic matrix composites. Large increases in flexural strengths were achieved in both systems demonstrating for the first time that discontinuous randomly oriented Pyrograf III™ can give strength increases and has substantial potential as a reinforcement in composites. Here-to-fore, addition of VGCF caused strength decreases. Voids, residual thermal strains (as the fiber surface area is ∽35 times greater than 7 μm-diameter PAN fiber), or uncertainties about fiber strength, fiber–matrix bonding and the degree of fiber dispersion, could cause losses of strength. Thermal conductivity properties of VGCF/ABS (acrylonitrile–butadiene–styrene from GE Plastics) and VGCF/epoxy composites with various fiber volume fractions were measured. Thermal conductivity increased with an increase in fiber volume fraction. However, these increases were not significant enough to make these VGCF fiber/organic matrix composites candidates for thermally conductive materials.

Conceptual and Practical Considerations for Sharing Catastrophic/Systemic Risks

Abstract: Catastrophic or systemic risks are a major challenge for the farm and food system and rural communities. Private sector markets for sharing catastrophic risks are limited, but less so than in the past. This article presents a conceptual base for understanding why markets for sharing catastrophic risks may be incomplete and/or inefficient. Next, federal efforts to address catastrophic risk losses are reviewed. Finally, new capital market developments are presented and an alternative is introduced where the government would write risk options for specific perils.

Relation between the solubility of proteins in aqueous solutions and the second virial coefficient of the solution

Abstract: In recent publications it was pointed out that there is a correlation between the observed values of the solubility of proteins in aqueous solutions and the second virial coefficient of the solution. In this paper we give a theoretical explanation of this relation. The derived theoretical expression describes the experimentally observed relation between solubility and virial coefficient quite accurately. It is concluded that a variation of the crystallization conditions has little effect on the anisotropy or the range of the interactions between the protein molecules. Analysis of the data for lysozyme indicates a strong anisotropy of the interactions between the molecules.

Perceived Cohesion in Small Groups: Adapting and Testing the Perceived Cohesion Scale in a Small-Group Setting

Abstract: The six-item Perceived Cohesion Scale (PCS) was created to measure perceived cohesion in groups. However, only large groups were used to assess the validity and reliability of the measure, leaving in question the use of the PCS with small groups. This study adapts the measure of cohesion to the small-group arena. Results provide support for the validity and reliability of the adapted measure for use within the small group.

Overview of Sensitivity Analysis and Shape Optimization for Complex Aerodynamic Configurations

Abstract: This paper presents a brief overview of some of the more recent advances in steady aerodynamic shape-design sensitivity analysis and optimization, based on advanced computational fluid dynamics. The focus here is on those methods particularly well- suited to the study of geometrically complex configurations and their potentially complex associated flow physics. When nonlinear state equations are considered in the optimization process, difficulties are found in the application of sensitivity analysis. Some techniques for circumventing such difficulties are currently being explored and are included here. Attention is directed to methods that utilize automatic differentiation to obtain aerodynamic sensitivity derivatives for both complex configurations and complex flow physics. Various examples of shape-design sensitivity analysis for unstructured-grid computational fluid dynamics algorithms are demonstrated for different formulations of the sensitivity equations. Finally, the use of advanced, unstructured-grid computational fluid dynamics in multidisciplinary analyses and multidisciplinary sensitivity analyses within future optimization processes is recommended and encouraged.

Protein kinase C in the treatment of disease: signal transduction pathways, inhibitors, and agents in development.

Abstract: Protein kinase C (PKC) is a family of enzymes that play a ubiquitous role in intracellular signal transduction. Our understanding of the precise role of PKC has evolved considerably as a result of improved methodology and a better understanding of the signal transduction pathways. A number of primary pathways previously attributed to PKC have been re-examined and found to involve other kinases as our understanding of the PKC isozymes has evolved. PKC isozymes appear to play distinct, and in some cases opposing roles in the transduction of intracellular signals. The development of potent and selective PKC inhibitors, including isozyme-selective inhibitors, has opened new avenues for biochemical and pharmaceutical studies. The role of PKC in some of the pathways relevant to cardiovascular, peripheral microvascular, CNS, oncology, immune and infectious disease states are surveyed. A survey of the current generation of potent and selective ATP-competitive inhibitors is provided. The progress of PKC inhibitors currently in clinical development, including LY333531, ISIS 3521 (CGP 64128A), bryostatin 1, GF109203x, Ro 32-0432 and Ro 31-8220, Go 6976 and Go 7611, CPR 1006, and balanol (SPC 100840) are discussed.

Temperature Regime and Carbon Dioxide Enrichment Alter Cotton Boll Development and Fiber Properties

Abstract: Temperature and atmospheric carbon dioxide concentration [CO{sub 2}] affect cotton (Gossypium hirsutum L.) growth and development, but the interaction of these two factors on bill and fiber properties has not been studied. An experiment was conducted in naturally lit plant growth chambers to determine the influence of temperature and atmospheric [CO{sub 2}] on cotton (cv. DPL-51) boll and fiber growth parameters. Five temperature regimes were evaluated: the 1995 temperature at Mississippi State, MS; the 1995 temperature minus 2 C; and the 1995 temperature plus 2, 5, and 7 C. Daily and seasonal variation and amplitudes were maintained. Atmospheric [CO{sub 2}] treatments were 360 (ambient) and 720 {micro}L L{sup {minus}1}. Boll number, boll growth, and fiber properties were measured. Boll size and maturation periods decreased as temperature increased. Boll growth increased with temperature to 25 C and then declined at the highest temperature. Boll maturation period, size, and growth rates were not affected by atmospheric [CO{sub 2}]. The most temperature-sensitive aspect of cotton development is boll retention. Almost no bolls were retained to maturity at 1995 plus 5 or 7 C, but squares and bolls were continuously produced even at those high temperatures. Therefore, the upper limit for cotton boll survivalmore » is 32 C, or 5 C warmer than the 1995 US Mid-South ambient temperatures. The 720 {micro}L L{sup {minus}1} atmospheric [CO{sub 2}] had about 40% more squares and bolls across temperatures than the 360 {micro}L L{sup {minus}1} [CO{sub 2}]. Fibers were longer when bolls grew at less than optimal temperatures (25 C) for boll growth. As temperature increased, fiber length distributions were more uniform. Fiber fineness and maturity increased linearly with the increase in temperature up to 26 C, but decreased at 32 C. Short-fiber content declined linearly from 17 to 26 C, but was higher at higher temperature. As for boll growth and developmental parameters, elevated atmospheric [CO{sub 2}] did not affect any of the fiber parameters. Changes in temperature, however, had a dramatic effect on boll set and fiber properties. The relationships between temperature and boll growth and developmental rate functions and fiber properties provide the necessary functional parameters to build fiber models under optimum water and nutrient conditions.« less

Political behaviors as moderators of the perceptions of organizational politics—work outcomes relationships

Abstract: This study investigates the complexities involved in the relationships between perceptions of politics and work outcomes by examining the effects of political behavior on that relationship. More specifically, we suggest that political behavior may serve as a form of control or as a mechanism for coping with highly political organizational environments perceived by individuals to be aversive. As such, we propose moderating roles of self-promotion and ingratiation on the relationships between perceptions of politics and the work outcomes of satisfaction with job in general, satisfaction with supervision, and intent to leave. It was hypothesized that increased exercise of self-promotion and ingratiation behaviors would mitigate the negative effects of perceptions of organizational politics on those specific outcomes. Hypotheses were supported for the proposed relationships between self-promotion and two of the work outcomes: satisfaction with supervision and intent to leave. Significant effects were also found for ingratiation; however, they were opposite to those proposed for the perceptions of organizational politics–intent to leave relationship. Implications of results and areas for future research are discussed. Copyright © 1999 John Wiley & Sons, Ltd.

ETHNIC AND CULTURAL DIVERSITY IN FATHERS' INVOLVEMENT A Racial/Ethnic Comparison of African American, Hispanic, and White Fathers

Abstract: Using national-level data, this analysis examines American fathers' participation in three domains of child rearing for children aged 5 to 18 years. Focus is placed on the extent to which participation varies by race or ethnicity, gender and family ideologies, and the interaction between these factors. Results show that minority fathers consistently outperform White fathers in the cognitive domain. Findings also show that fathers' involvement is a function of an interplay between race or ethnicity and cultural ideologies.

Conservation Reserve Program: source or sink habitat for grassland birds in Missouri?

Abstract: The Conservation Reserve Program (CRP) has been eredited with contributing substantially to the conservation of grassland birds. Although many species have nested in grasslands established under the CRP, little evidence of positive effect on populations has been reported. We measured reproductive rates and estimated fecundity of 7 grassland bird species in CRP fields in northern Missouri and compared those rates to estimates of fecundity needed to maintain stable populations (λ = 1). Under conservative assumptions of survival, CRP fields seemingly were source habitats (fecundity exceeded levels necessary for λ = 1) for grasshopper sparrows (Ammodramus savannarum) and field sparrows (Spizella pusilla) in at least 2 of 3 years (1993: P = 0.02, 1995: P < 0.001) and pooled over 3 years (Ps < 0.001). Although evidence was less compelling, CRP fields were likely source habitat for eastern meadowlarks (Sturnella magna) and American goldfinches (Carduelis tristis). For American goldfinches, fecundity was greater than that necessary for λ = 1 in 1995 (P < 0.001), and pooled over 3 years (P < 0.001). Our pooled estimate of fecundity was greater than necessary for λ = 1 for eastern meadowlarks (Ps < 0.001), but only under a liberal assumption of survival in 2 of 3 years (1993: P = 0.001; 1995: P = 0.088). Fecundity of common yellowthroats (Geothlypis trichas) varied substantially; therefore, source-sink status alternated among years, although the pooled estimate of fecundity was less than required for λ = 1 (P < 0.001). Dickcissel (Spiza americano) fecundity was consistently less than necessary for λ = 1 (conservative survival assumption: all Ps < 0.001; liberal survival assumption: 1994 P - 0.008. pooled P = 0.014). For red-winged blackbirds (Agelaius phoeniceus), CRP fields were consistently a sink habitat (all Ps < 0.001). Based on our evidence, the CRP likely has contributed to the conservation of grasshopper sparrows, field sparrows. and eastern meadowlarks. Although large numbers of dickcissels and red-winged black-birds nested in CRP fields, there is little evidence that the CRP has contributed to populations of those species.

Effects of water-column enrichment on the production dynamics of three seagrass species and their epiphytic algae

Abstract: Monospecific beds of the seagrasses Halodule wrightii, Syringodium filiforme and Thalassia testudinum were enriched with a slow-release Osmocote (N-P-K) fertilizer from August 1993 through September 1994. Primary production rates (as 14 C uptake), biomass (dry weight), and chlorophyll a (chl a) (measured by HPLC) of epiphytes in enriched beds were significantly greater than those of epiphytes in control beds. Based on microscopic observations, the dominant epiphytic algae were diatoms and red and brown algae. Populations of the brown alga Myriotrichia subcorymbosa and the red alga Acrochaetium flexuosum increased greatly in enriched plots of all 3 seagrass species. Multiple linear regression supported observational data in that pigment signatures selected for the dominant epiphytes (fucoxanthin, zeaxanthin, and violaxanthin) explained 97% of the variation in chl a. A strong correlation between measured and predicted chl a (r = 0.98) suggested that chl a is an excellent indicator of epiphytic biomass in this system. Production rates of blades increased in enriched plots relative to controls but biomass of blades was unaffected. The strong response of epiphytes to enrichment suggests that cultural eutrophication could pose a threat to seagrass beds of Big Lagoon, Perdido Key, Florida, USA. Negative effects could be manifested as a reduction in the coverage of shallow-water sediments by seagrass beds and/or the elimination of 1 or 2 species, possibly converting Big Lagoon into a seagrass monoculture.

Effects of Tropospheric O3 on Trembling Aspen and Interaction with CO2: Results from an O3-Gradient and a Face Experiment

Abstract: Over the years, a series of trembling aspen (Populus tremuloides Michx.) clones differing in O3 sensitivity have been identified from OTC studies. Three clones (216 and 271[(O3 tolerant] and 259 [O3 sensitive]) have been characterized for O3 sensitivity by growth and biomass responses, foliar symptoms, gas exchange, chlorophyll content, epicuticular wax characteristics, and antioxidant production. In this study we compared the responses of these same clones exposed to O3 under field conditions along a natural O3 gradient and in a Free-Air CO2 and O3 Enrichment (FACE) facility. In addition, we examined how elevated CO2 affected O3 symptom development. Visible O3 symptoms were consistently seen (5 out of 6 years) at two of the three sites along the O3 gradient and where daily one-hour maximum concentrations were in the range of 96 to 125 ppb. Clonal differences in O3 sensitivity were consistent with our OTC rankings Elevated CO2 (200 ppm over ambient and applied during daylight hours during the growing season) reduced visible foliar symptoms for all three clones from 31 to 96% as determined by symptom development in elevated O3 versus elevated O3 + CO2 treatments. Degradation of the epicuticular wax surface of all three clones was found at the two elevated O3 gradient sites. This degradation was quantified by a coefficient of occlusion which was a measure of stomatal occlusion by epicuticular waxes. Statistically significant increases in stomatal occlusion compared to controls were found for all three clones and for all treatments including elevated CO2, elevated O3, and elevated CO2 + O3. Our results provide additional evidence that current ambient O3 levels in the Great Lakes region are causing adverse effects on trembling aspen. Whether or not elevated CO2 in the future will alleviate some of these adverse effects, as occurred with visible symptoms but not with epicuticular wax degradation, is unknown.

Minsize2: a Computer Program for Determining Effect Size and Minimum Sample Size for Statistical Significance for Univariate, Multivariate, and Nonparametric Tests:

Abstract: The American Psychological Association’s editorial style urges authors to provide effect size estimates. Several journals, including Educational and Psychological Measurement, have adopted author g...

Relationship between instrumental and sensory measurements of cheese texture

Abstract: The relationship between sensory and instrumental texture measurements of natural and processed cheeses was studied. A descriptive analysis panel evaluated seven mouth-evaluated and five hand-evaluated texture terms. Instrumental measurements included texture profile analysis (TPA), frequency sweeps, and creep. Multivariate analyses showed that many of the sensory and instrumental analyses were highly correlated. Principal component analysis showed similarities and differences in how the cheeses were differentiated by sensory and instrumental techniques. TPA and fundamental rheological tests worked equally well at predicting sensory attributes of the cheeses, but TPA was better at predicting sensory attributes when cheeses were divided into two groups, natural and processed. Instrumental measurements predicted sensory attributes of processed cheeses better than natural cheeses. While fundamental rheological tests reveal important information on network structure and molecular arrangement, these results indicate that empirical texture evaluations work equally well or better at predicting sensory texture properties.