Low Rate Treatment Research Articles

Clinical translation of the ABA renewal model of treatment relapse

ABSTRACTAn 18-year-old male’s attention-maintained problem behavior was treated with an alternative (ALT) variable-interval, variable-time (VI VT) schedule arrangement with two therapists each delivering attention at different rates in a multiple schedule of reinforcement. Despite the differing rates of VI VT attention, the procedures resulted in similar rates of problem behavior in the last three treatment sessions reducing problem behavior by an average of 45%. Following treatment, the two therapists conducted separate extinction sessions, initially in a different context until problem behavior extinguished and then returning to the original treatment context (i.e., the ABA renewal test). Extinction took 4.4 times longer in the renewal test for the therapist who implemented the high-rate VI VT treatment compared with the therapist who implemented the low-rate VI VT treatment. Although these results are preliminary, the implications for clinicians is that treatment designs that use low-rate treatment may be more effective than high-rate treatment in preventing relapse.

Emissions and distribution of methyl bromide in field beds applied at two rates and covered with two types of plastic mulches

A field experiment was conducted to compare two plastic mulches and two application rates on surface emissions and subsurface distribution of methyl bromide (MBr) in field beds in Florida. Within 30 minutes after injection of MBr to 30 cm depth, MBr had diffused upward to soil surface in all beds covered with polyethylene film (PE) or virtually impermeable film (VIF) and applied at a high rate (392 kg/ha) and a low rate (196 kg/ha). Due to the highly permeable nature of PE, within 30 minutes after injection, MBr volatilized from the bed surfaces of the two PE-covered beds into the atmosphere. The amount of volatilization was greater for the high rate-treatment bed. On the other hand, volatilization of MBr from the bed surfaces of the two VIF-covered beds were negligible. Volatilization losses occurred from the edges of all the beds covered with PE or VIF and were greater from the high rate-treatment beds. Initial vertical diffusion of MBr in the subsurface of the beds covered with PE or VIF was mainly upward, as large concentrations of MBr were detected from near bed surfaces to 20 cm depth in these beds 30 minutes after injection and little or no MBr was found at 40 cm depth. The two VIF-covered beds exhibited greater MBr concentrations and longer resident times in the root zone (0.5–40 cm depth) than corresponding PE-covered beds. Concentrations of MBr in the root zone of the high rate-treatment beds were 3.6–6.1 times larger than the low rate-treatment beds during the first days after application. In conclusion, VIF promoted retention of MBr in the root zone and, if volatilization loss from bed edges can be blocked, volatilization loss from VIF-covered beds should be negligible.

BACTERIA AND NUTRIENT TRANSPORT TO TILE LINES SHORTLY AFTER APPLICATION OF LARGE VOLUMES OF LIQUID SWINE MANURE

The rapid growth and concentration of the livestock production industry has increased concerns about potentialwater quality problems from land application of manure. A study was conducted using 14 lysimeters to observe the transportof bacteria and nutrients with subsurface drainage water as a function of liquid swine manure application rate. Lagoon liquidwas surfaceapplied to notill soil in lysimeters at rates of 0 (control), 280,000 and 830,000 L/ha. At the lower rate, twoadditional management strategies or treatments were used: tilling the surface soil before application, and airpressurizingthe drainage tube in the lysimeters during and after application. The subsurface drainage water was analyzed for flow volume,bacteria, and nutrients. The higher rate of application initiated flow and increased levels of nutrient and bacterialcontamination within 1 h after application as well as throughout the 15day study period. Notill lysimeters had flow andhigher levels of contamination earlier in the study than did tilled or airpressurized lysimeters. Although there were noconsistent statistically significant differences between the control and the lowerrate treatments nor between individuallowerrate treatments, there were statistically significant differences between the high and lowrate treatments, whichsuggest that overapplication of liquid swine manure poses a direct threat to water quality.