EXPATRIATES OF GOOD MOTHERHOOD: BEARING WITNESS, GUILT, AND BURDENS OF TRANSGRESSIVE MOTHERHOOD

To be an expatriate requires emotional stamina to withstand culture shock, loneliness, and self-doubt. To be an expatriate of “good” motherhood is no less shocking, no less lonely, and no less anxiety-inducing. This collection braids original creative pieces with critical inquiry into the roots of disorienting riptides of motherhood mythology. The creative pieces include flash nonfiction essays and poetry; the critical inquiry explores historical narratives, critical theory, feminist theory, and literary narratives. By braiding these different forms, the work aims to create a collage of cultural artifacts, whose composition can better illuminate the darkest corners of elusive motherhood mythology

Influence of Rough and Smooth Walls on Macroscale Flows in Tumblers

Walls in discrete element method simulations of granular flows are sometimes modeled as a closely packed monolayer of fixed particles, resulting in a rough wall rather than a geometrically smooth wall. An implicit assumption is that the resulting rough wall differs from a smooth wall only locally at the particle scale. Here we test this assumption by considering the impact of the wall roughness at the periphery of the flowing layer on the flow of monodisperse particles in a rotating spherical tumbler. We find that varying the wall roughness significantly alters average particle trajectories even far from the wall. Rough walls induce greater poleward axial drift of particles near the flowing layer surface, but decrease the curvature of the trajectories. Increasing the volume fill level in the tumbler has little effect on the axial drift for rough walls, but increases the drift while reducing curvature of the particle trajectories for smooth walls. The mechanism for these effects is related to the degree of local slip at the bounding wall, which alters the flowing layer thickness near the walls, affecting the particle trajectories even far from the walls near the equator of the tumbler. Thus, the proper choice of wall conditions is important in the accurate simulation of granular flows, even far from the bounding wall.Comment: 32 pages, 19 figures, regular article, accepted for publication in Physical Review E 200

Behavioral Effects of Inhibition of Cyclic Nucleotide Phosphodiesterase 2 (PDE2) in Mice

Cyclic nucleotide phosphodiesterases (PDEs) are a super-family of enzymes that regulate intracellular levels of the second messengers, cyclic AMP and cyclic GMP. Multiple PDEs have been shown to play vital roles in the central nervous system, with involvement in mood, reward mechanisms, and learning and memory. PDE2 is of special interest due to its high level of expression in forebrain regions, which are specifically implicated in mood and memory processes. In the first set of experiments, the potential role of PDE2 in depression- and anxiety-like behaviors was investigated using the forced swim test, tail suspension test, elevated plus maze, hole-board and step-through passive avoidance tests, as well as the object recognition test (ORT). The PDE2-selective inhibitor, Bay 60-7550 (3 mg/kg) did not significantly alter any of the depression- or anxiety-like behaviors, but did significantly enhance memory in the ORT. In the next set of experiments, the ORT was used to investigate the effect of PDE2 inhibition on various stages of learning and memory. Bay 60-7550 was administered 30-120 min prior to training, 0, 1, or 3 hrs after training, or 30 min prior to recall testing. Next, inhibitors of the cAMP or cGMP signaling pathways were administered 30 min prior to the PDE2 inhibitors Bay 60-7550 or ND7001, to assess the role cyclic nucleotide signaling on PDE2 inhibitor-enhanced memory. Finally, changes in the phosphorylation of CREB at Ser-133 and VASP at Ser-239 were determined to confirm activation of cAMP and cGMP signaling by PDE2 inhibition at behaviorally relevant doses. Bay 60-7550 (3 mg/kg) significantly enhanced memory of mice in the ORT when given 30 min prior to training, immediately after training, or 30 min prior to recall. Inhibitors of the cGMP pathway blocked the memory-enhancing effects of both Bay 60-7550 (3 mg/kg) and ND7001 (3 mg/kg). Bay 60-7550 (3 mg/kg) significantly enhanced the phosphorylation of CREB and VASP, both targets of PKG. While PDE2 inhibition did not appear to play a major role in depression- and anxiety-like behaviors in these tests, future research will further elucidate the role of PDE2 in other mood-related behavior tests. Additionally, PDE2 does appear to play a major role in learning and memory, as seen in the ORT. Developing a greater understanding of the role of PDE-2 in these memory processes will allow for potential drug development for the intervention of a variety of human diseases related to cognitive decline and memory impairment, which plague millions of individuals each year

Rotating Reverse-Osmosis for Water Purification

A new design for a water-filtering device combines rotating filtration with reverse osmosis to create a rotating reverse- osmosis system. Rotating filtration has been used for separating plasma from whole blood, while reverse osmosis has been used in purification of water and in some chemical processes. Reverse- osmosis membranes are vulnerable to concentration polarization a type of fouling in which the chemicals meant not to pass through the reverse-osmosis membranes accumulate very near the surfaces of the membranes. The combination of rotating filtration and reverse osmosis is intended to prevent concentration polarization and thereby increase the desired flux of filtered water while decreasing the likelihood of passage of undesired chemical species through the filter. Devices based on this concept could be useful in a variety of commercial applications, including purification and desalination of drinking water, purification of pharmaceutical process water, treatment of household and industrial wastewater, and treatment of industrial process water. A rotating filter consists of a cylindrical porous microfilter rotating within a stationary concentric cylindrical outer shell (see figure). The aqueous suspension enters one end of the annulus between the inner and outer cylinders. Filtrate passes through the rotating cylindrical microfilter and is removed via a hollow shaft. The concentrated suspension is removed at the end of the annulus opposite the end where the suspension entered

Slow axial drift in three-dimensional granular tumbler flow

Models of monodisperse particle flow in partially filled three-dimensional tumblers often assume that flow along the axis of rotation is negligible. We test this assumption, for spherical and double cone tumblers, using experiments and discrete element method simulations. Cross sections through the particle bed of a spherical tumbler show that, after a few rotations, a colored band of particles initially perpendicular to the axis of rotation deforms: particles near the surface drift toward the pole, while particles deeper in the flowing layer drift toward the equator. Tracking of mm-sized surface particles in tumblers with diameters of 8-14 cm shows particle axial displacements of one to two particle diameters, corresponding to axial drift that is 1-3% of the tumbler diameter, per pass through the flowing layer. The surface axial drift in both double cone and spherical tumblers is zero at the equator, increases moving away from the equator, and then decreases near the poles. Comparing results for the two tumbler geometries shows that wall slope causes axial drift, while drift speed increases with equatorial diameter. The dependence of axial drift on axial position for each tumbler geometry is similar when both are normalized by their respective maximum values