Regression Analysis as an Alternative to Difference Scores

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68519/2/10.1177_014920639402000311.pd

Bridging the Great Divide Between Theoretical and Empirical Management Research

Management research places a great premium on theory development. Despite this emphasis, concerns have been expressed regarding the extent to which management theories are tested in empirical research. This article reviews evidence concerning the connections between theoretical and empirical management research and reports an investigation that examines the correspondence between the propositions presented in 20 highly cited theoretical articles and the hypotheses stated in 361 empirical articles that cite the theories. Results indicate that the vast majority of theoretical propositions are not translated into empirical hypotheses, indicating a great divide between theoretical and empirical management research. Implications of these results are discussed, and potential solutions are offered

Heritability of root characteristics affecting mineral uptake in tall fescue

Modification of plant roots can potentially increase the area. of adaptation of tall fescue (Festuca arundinacea Schreb.). Limited information is available on the heritability of root diameter and root volume in tall fescue. A greenhouse experiment was conducted with\u2750 random \u27Kentucky 31\u27 (Ky-31) tall fescue parents and their progeny grown in aerated nutrient solution during four separate time intervals. Measurements of root volume, root diameter, shoot Mg concentration, and shoot K/(Mg + Ca) ratio were made six weeks after clonal material was transplanted in nutrient solution. Heritability estimates for root volume, root diameter, shoot Mg concentration, and shoot K/(Mg +Ca)ratios were determined. Broad sense heritabilities were 0.60, 0.65, 0.32, and 0.58 for root volume, root diameter, Mg concentration, and K/(Mg + Cal ratios, respectively. Narrow sense heritabilities were 0.41, 0.18,0.19, and 0.58

Investigation of Synthesis and Processing of Cellulose, Cellulose Acetate and Poly(Ethylene Oxide) Nanofibers Incorporating Anti-Cancer/Tumor Drug Cis-Diammineplatinum (II) Dichloride Using Electrospinning Techniques

A model anti-cancer/tumor drug cis-diammineplatinum (II) dichloride (cisplatin) was loaded into micro- and nanofibers of cellulose, cellulose acetate (CA) and poly(ethylene oxide) (PEO), using various electrospinning techniques. Single-nozzle electrospinning was used to fabricate neat fibers of each category. Drug loading in cellulose fibers was performed using single-nozzle electrospinning. Encapsulation of cisplatin in CA and PEO-based fibers was performed using coaxial electrospinning. Morphological analysis of the fibers was performed using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The various categories of fibers exhibited diverse morphological features depending on the material compositions and applied process parameters. The drug-loaded cellulose nanofibers showed attached particles on the surface. These particles were composed of both the polymer and the drug. The CA-cisplatin fibers exhibited drug encapsulation within various diverse morphological conformations: hierarchical structures such as straw-sheaf-shaped particles, dendritic branched nanofibers and swollen fibers with large beads. However, in the case of PEO fibers, drug encapsulation was observed inside repeating dumbbell-shaped structures. Morphological development of the fibers and corresponding mode of drug encapsulation were correlated with process parameters such as applied voltage, concentrations and relative feed rates of the solutions and conductivities of the solvents

Smoothing tautologies, hidden dynamics, and sigmoid asymptotics for piecewise smooth systems

Switches in real systems take many forms, such as impacts, electronic relays, mitosis, and the implementation of decisions or control strategies. To understand what is lost, and what can be retained, when we model a switch as an instantaneous event, requires a consideration of so-called hidden terms. These are asymptotically vanishing outside the switch, but can be encoded in the form of nonlinear switching terms. A general expression for the switch can be developed in the form of a series of sigmoid functions. We review the key steps in extending the Filippov's method of sliding modes to such systems. We show how even slight nonlinear effects can hugely alter the behaviour of an electronic control circuit, and lead to `hidden' attractors inside the switching surface.Comment: 12 page

Heroic Helping: The Effects of Priming Superhero Images on Prosociality

Two experiments examined how exposure to superhero images influences both prosociality and meaning in life. In Experiment 1 (N = 246) exposed individuals to scenes with superhero images or neutral images. Individuals primed with superhero images reported greater helping intentions relative to the control group, which, in turn, were associated with increased meaning in life (indirect effect only; no direct effect). In Experiment 2 (N = 123), individuals exposed to a superhero poster helped an experimenter in a tedious task more than those exposed to a bicycle poster, though no differences were found for meaning in life. These results suggest that subtle activation of superhero stimuli increases prosocial intentions and behavior

Insights on lava–ice/snow interactions from large-scale basaltic melt experiments

Quantitative measurements of interactions between lava and ice/snow are critical for improving our knowledge of glaciovolcanic hazards and our ability to use glaciovolcanic deposits for paleoclimate reconstructions. However, such measurements are rare because the eruptions tend to be dangerous and not easily accessible. To address these difficulties, we conducted a series of pilot experiments designed to allow close observation, measurements, and textural documentation of interactions between basaltic melt and ice. Here we report the results of the first experiments, which comprised controlled pours of as much as 300 kg of basaltic melt on top of ice. Our experiments provide new insights on (1) estimates for rates of heat transfer through boundary layers and for ice melting; (2) controls on rates of lava advance over ice/snow; (3) formation of lava bubbles (i.e., Limu o Pele) by steam from vaporization of underlying ice or water; and (4) the role of within-ice discontinuities to facilitate lava migration beneath and within ice. The results of our experiments confirm field observations about the rates at which lava can melt snow/ice, the efficacy with which a boundary layer can slow melting rates, and morphologies and textures indicative of direct lava-ice interaction. They also demonstrate that ingestion of external water by lava can create surface bubbles (i.e., Limu) and large gas cavities. We propose that boundary layer steam can slow heat transfer from lava to ice, and present evidence for rapid isotopic exchange between water vapor and melt. We also suggest new criteria for identifying ice-contact features in terrestrial and martian lava flows

Ambulatory Electromyogram Activity in the Upper Trapezius Region: Patients With Muscle Pain vs. Pain-free Control Subjects

Study Design: This study compared the ambulatory electromyogram activity of persons reporting pain in the shoulder and cervical regions with an equal group of persons not reporting such pain. Ambulatory electromyogram data were obtained over 3-day periods. In addition, all participants completed several standard psychological questionnaires. Objectives: The results were analyzed with inferential statistics to determine whether subjects reporting significant pain in the shoulder and cervical regions had greater ambulatory electromyogram activity than an equal number of subjects not reporting pain. Summary of Background Data: Considerable controversy exists regarding the role of muscle activity in the etiology and maintenance of muscle pain disorders. Given the availability of ambulatory recording devices that can provide a detailed record of muscle activity over an extended period of time, the present research was conducted to determine whether persons reporting shoulder and cervical pain could be differentiated from a group of normal subjects. Methods: All subjects (N = 20) completed a battery of tests with standardized psychometric instruments and then were fitted with ambulatory electromyogram monitors to record electromyographic activity of the upper trapezius region of the dominant side; the time, duration, and amplitude of electromyogram activity greater than 2 μV was recorded. The monitors were worn during normal working hours (mean, 6.2 hours per day) over 3 consecutive days. In addition to wearing the monitors, all subjects completed hourly self-ratings of perceived muscle tension during the recording periods. Results: As expected, subjects with muscle pain reported significantly more pain (mean, 4.9) than did the normal control subjects (mean, 0.9), t(15) = 3.29, P \u3c 0.01. However, patients with muscle pain did not have greater average electromyogram activity (mean, 6.4 μV) over the 3-day period as compared to the normal controls (mean, 7.1 μV), t(18) = -0.25, P \u3c 0.80. Self-monitoring of perceived muscle tension also did not reveal differences between pain subjects and the normal control subjects (P \u3c 0.75). Conclusions: Ambulatory measurements of electromyogram activity did not differentiate persons reporting upper trapezius or cervical pain from those that did not report such pain. Persons reporting pain are also not distinguishable from normal control subjects on a variety of self-report measures. These results raise questions regarding the role of ambulatory electromyogram recordings in the evaluation and treatment of muscle pain disorders