Models are developed to examine the determinants of weekly truck rates for produce shipped to the Northeast from California and Florida. In the empirical work, a large proportion of the variation in rates is explained and the estimated parameters are generally consistent with a priori expectations. The total quantity of produce shipped from each state, the proportion of this total which is compatible with the commodity in question, and the F.O.B. price if the commodity were found to be the most important determinants of truck rate levels. Fuel costs have a surprisingly weak influence, at least in the short run, and for Florida origin commodities the truck rate-fuel cost relationship appears to have weakened over the 1979–1983 sample period.

Regulation of human T cell leukemia virus type II (HTLV-II) gene expression by Rex is mediated by cis-acting elements in the 5' viral long terminal repeat (LTR). Rex acts posttranscriptionally to enhance cytoplasmic accumulation of incompletely spliced viral mRNAs encoding structural proteins. We report a distinct negative regulatory function mediated by Rex affecting expression from the viral 5' LTR. Using both LTR-driven CAT reporters and a full-length HTLV-II proviral construct, we demonstrate that Rex decreases total cellular levels of LTR-containing mRNA in a dose-dependent manner. Negative regulation is an independent function as demonstrated by structural and functional dissociation from Rex positive posttranscriptional regulation. This negative regulatory action was dependent on nuclear localization sequences, but did not require the previously defined Rex-responsive element (RxRE). Negative regulation was observed in T cell lines but not in B cell lines, suggesting the involvement of cell type-specific factors distinct from those involved in posttranscriptional regulation. An internal deletion mutant of Rex removing aa 38-80 retained the ability to repress, but did not posttranscriptionally increase expression, while negative regulation requires a previously uncharacterized carboxy-terminal region (aa 154-170). These findings suggest that Rex may serve two simultaneous functions: to decrease overall levels of transcribed viral mRNA, and to facilitate nuclear to cytoplasmic export of mRNAs encoding structural proteins. The negative regulatory function of Rex may play a role in viral latency.

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We describe a short, interactive case-based activity for illustrating cognitive distortions of communication underlying resistance to change. Based on a real-life story, the case describes a failed effort by the mayor of Toowoomba, Australia to fund a state-of-the-art wastewater treatment plant. After reading the case, students work individually and in small groups to identify examples of cognitive distortions in the communication between the mayor’s office and the citizens of Toowoomba and then suggest better approaches based on evidence-based principles of persuasion. The Wastewater case is both engaging and versatile and has proven popular for students in undergraduate, graduate, and executive education courses. We discuss learning objectives, provide step-by-step instructions for running the activity, describe variations and adaptations for online courses, and include suggestions for debriefing the activity.