Empirical validation of a modern genetics progression web for college biology students

ABSTRACT

Research in learning progressions (LPs) has been essential towards building understanding of how students’ ideas change over time. There has been little work, however, into how ideas between separate but related constructs within a multi-faceted LP relate. The purpose of this paper is to elaborate on the idea of progression webs to model connections within and between related constructs simultaneously, and to explain and demonstrate the efficacy of path analysis towards validating a hypothesised progression web for understanding of modern genetics. Specifically, we evaluate strength of evidence for a progression web based upon multiple related constructs within a multi-faceted LP describing undergraduate biology students’ understanding of genetics. We then utilise the progression web to generalise theory around how undergraduate students understand relationships between related genetics concepts, and how they use simpler concepts to scaffold those which are more complex.     

Knee extensor and flexor torque development with concentric and eccentric isokinetic training

This study assessed muscular torque and rate of torque development following concentric (CON) or eccentric (ECC) isokinetic training. Thirty-eight women were randomly assigned to either CON or ECC training groups. Training consisted of knee extension and flexion of the nondominant leg three times per week for 20 weeks (SD = 1). Eccentric training increased ECC knee extension and flexion peak torque more than CON training. The ECC group improved acceleration time and time to peak torque with ECC movements versus the CON group. Slow-velocity ECC isokinetic training yielded greater ECC and similar CON torque development gains versus CON training over the course of 20 weeks in young women.     

Adjunctive behavior of the rat under periodic food delivery in a 24-hour environment

The behavior of 4 rats living in complex environments was monitored 24 h per day during free-feeding baseline and under conditions of periodic access to food. Under the periodic schedules, the minimum interfood interval (IFI) was increased from 16 to 512 sec in an ascending series. Periodic food produced robust overall increases in investigation of the feeder, drinking, general activity, and rearing, but not in wheel-running. The temporal distribution of behavior within the IFI was similar across subjects and supported the hypothesis that some responses were largely time-locked to the period immediately following eating, while other responses expanded to fill the interval. However, these response differences were not adequately captured by present classification schemes. Finally, the distribution of drinking following a food pellet strongly resembled the distribution of drinking following bouts of feeding in baseline. The results suggest that adjunctive behavior stems from three sources: (1) a simple increase in the number of opportunities for expression of normal preprandial and postprandial behavior, (2) an increase in the preprandial behavior directed toward the site of expected food, and (3) an increase in the postprandial distribution of both site-directed and more general exploratory behavior. These findings suggest that adjunctive behavior is not extraneous, but is an orderly distribution of responses ordinarily related to feeding and foraging for food.     

Hematological Variations during Aerobic Training of College Women

Abstract

The purpose of this study was to observe the effects of a progressive aerobic training program on hemoglobin concentration (Hb), hematocrit (Hct), red blood cell (RBC) count, mean RBC size (MCV), and mean corpuscular hemoglobin (MCH) of college women (N = 19). Training consisted of jogging (3 × week) one mile per session (Week 1) with a progressive increase in duration to five miles per session (Week 9). Training intensity elicited heart rates between 165–185 beats per minute. Blood samples were taken before training and after approximately two, five, seven, and nine weeks. Maximal oxygen uptake (ml/kg · min^?1) increased significantly during training from 41.2 ± 0.7 ( ± SE) to 44.7 ± 0.7. Initial values of Hb, Hct, RBC count, MCV, and MCH were 14.7 ± 0.13 g/dl, 40.4 ± 0.46%, 4.5 ± 0.5 × 10⁶/mm³, 89.0 ± 1.1/μ³, and 32.4 ± 0.4 μμg respectively. Orthogonal polynominal regression indicated significant decreasing quadratic trends for Hb, Hct, and RBC count, a significant cubic trend for MCV, and no change in MCH during training. Despite the initial trends, values that changed did return to near pretraining levels by the end of the nine-week program. Values for all blood parameters remained within normal ranges throughout the study. These data suggest that although aerobic training of increasing intensity in young women may be accompanied initially by decreases in Hb, Hct, and RBC count and an increase in MCV, these changes are only transitory. If such changes result from RBC destruction rather than hemodilution, the return to hematopoietic balance could impose a draw on body iron stores.     

Influence of Motor and Sensory Sets on Reaction Latency and Speed of Discrete Movements

Abstract

College men and women were tested as to reaction time and speed of an arm movement using both motor-oriented and stimulus-oriented set. The results confirmed a hypothesis based on neuromotor coordination theory that predicted slower movement and greater reaction latency when the motor set was used. However, the 20 percent of subjects who had a natural motor set tendency moved faster with an enforced motor set than with an enforced sensory set. The conditions of enforced set caused a moderate positive correlation between reaction and movement times. Women subjects reacted and moved slower than men, but were similarly influenced by the two enforced set conditions. Their natural set tendency was definitely stimulus-oriented, while men tended to have a neutral orientation.     

Real-time dynamics in the interaction between a trial stimulus and its temporal context

Learning & Behavior - Real-time changes in the interaction of a trial stimulus and the temporal properties of the interfood context were observed. An autoshaping procedure with pigeons...     

The effect of scopolamine on reference and working memory in pigeons

A comparison of the effects of scopolamine hydrobromide on working memory and reference memory in White Carneaux pigeons was undertaken by means of a modified delayed matching-to-sample procedure. Performance on working-memory trials was disrupted by decreases in sample duration and intertriai interval and by increases in delay interval. Performance on reference memory trials was not disrupted by any of these parametric manipulations. In Experiment 1, the pigeons received injections of scopolamine hydrobromide (0.01, 0.05, or 0.1 mg/kg), scopolamine methyl bromide (0.1 mg/kg), or saline prior to test sessions. In Experiment 2, the pigeons received injections of scopolamine hydrobromide (0.01 or 0.03 mg/kg), scopolamine methyl bromide (0.03 mg/kg), or saline. In both experiments, scopolamine hydrobromide had greater disruptive effects on working-memory trials than on reference-memory trials. The centrally active form of scopolamine disrupted working-memory trial accuracy more than the peripherally active form. However, no drug dose × delay interval interaction was obtained. Thus, the interference on working-memory-trial accuracy produced by central cholinergic blockade would not appear to be due to alterations in the active maintenance of information during the delay interval.