The Throne

The Throne is a publication of the Earl Gregg Swem Library made available in the building's restrooms

The Effect of Math-E-Motion on Children’s Mental Rotation Abilities and Spatial Perspective Taking Abilities

The demand for Science, Technology, Engineering, and Mathematics (STEM)-related jobs is increasing, while the number of educated and skilled people in this field is decreasing. Uttal, Meadow et al. (2012) emphasized that the development of a person’s spatial skills contributes to an individual’s success in STEM-related fields. In addition, Uttal, Meadow et al. recommended the investigation of the impact of spatial training on younger students. The purpose of this research was to determine the effect of a dynamic, fully-embodied learning activity on the development of elementary school students’ spatial skills; in particular, their mental rotation and spatial perspective taking abilities. Based on the difference between the students’ pre-test and post-test scores in the Object Rotation Test and the Perspective Taking Test, it was concluded that a dynamic, fully-embodied learning activity improves the students’ object rotation abilities and spatial perspective taking abilities

Sumudu-Bernstein solution of differential, integral and integro-differential equations

A numerical method based on the inverse Sumudu transform and the Bernstein polynomials operational matrix of integration is developed. The derived method is implemented in solving linear differential, integral and integro-differential equations. Also, a procedure for overcoming nonlinearity is developed and implemented to solve nonlinear Volterra integral equations. The approximate results are compared with the exact solutions and an existing method. Error estimation shows that the proposed method has elevated level of accuracy for just a few terms of the polynomial

Cyanide Production by Chromobacterium piscinae Shields It from Bdellovibrio bacteriovorus HD100 Predation

Predation of Chromobacterium piscinae by Bdellovibrio bacteriovorus HD100 was inhibited in dilute nutrient broth (DNB) but not in HEPES. Experiments showed that the effector responsible was present in the medium, as cell-free supernatants retained the ability to inhibit predation, and that the effector was not toxic to B. bacteriovorus. Violacein, a bisindole secondary metabolite produced by C. piscinae, was not responsible. Further characterization of C. piscinae found that this species produces sufficient concentrations of cyanide (202 mu M) when grown in DNB to inhibit the predatory activity of B. bacteriovorus, but that in HEPES, the cyanide concentrations were negligible (19 mu M). The antagonistic role of cyanide was further confirmed, as the addition of hydroxocobalamin, which chelates cyanide, allowed predation to proceed. The activity of cyanide against B. bacteriovorus was found to be twofold, depending on the life cycle stage of this predator. For the attack-phase predatory cells, cyanide caused the cells to lose motility and tumble, while for intra-periplasmic predators, development and lysis of the prey cell were halted. These findings suggest that cyanogenesis in nature may be employed by the bacterial strains that produce this compound to prevent and reduce their predation by B. bacteriovorus. IMPORTANCE Bacterial predators actively attack, kill, and enter the periplasm of susceptible Gram-negative bacteria, where they consume the prey cell components. To date, the activity of B. bacteriovorus HD100 has been demonstrated against more than 100 human pathogens. As such, this strain and others are being considered as potential alternatives or supplements to conventional antibiotics. However, the production of secondary metabolites by prey bacteria is known to mitigate, and even abolish, predation by bacterivorous nematodes and protists. With the exception of indole, which was shown to inhibit predation, the effects of bacterial secondary metabolites on B. bacteriovorus and its activities have not been considered. Consequently, we undertook this study to better understand the mechanisms that bacterial strains employ to inhibit predation by B. bacteriovorus HD100. We report here that cyanogenic bacterial strains can inhibit predation and show that cyanide affects both attack-phase predators and those within prey, i.e., in the bdelloplast