A perturbation analysis of spontaneous action potential initiation by stochastic ion channels

A stochastic interpretation of spontaneous action potential initiation is developed for the Morris- Lecar equations. Initiation of a spontaneous action potential can be interpreted as the escape from one of the wells of a double well potential, and we develop an asymptotic approximation of the mean exit time using a recently-developed quasi-stationary perturbation method. Using the fact that the activating ionic channel’s random openings and closings are fast relative to other processes, we derive an accurate estimate for the mean time to fire an action potential (MFT), which is valid for a below-threshold applied current. Previous studies have found that for above-threshold applied current, where there is only a single stable fixed point, a diffusion approximation can be used. We also explore why different diffusion approximation techniques fail to estimate the MFT

Optimizing natural fibers processing for use in plastics reinforcement

Author institution (Keener): Department of Food, Agricultural, and Biological Engineering, The Ohio State Universit

Waiting for the End of the World

This non-fiction essay collection examines the author\u27s entry into what Jane Smiley terms the age of grief. Smiley describes it as a period in a person\u27s life when she realizes a lot of acquaintances and friends have died and all the others are getting ready to sooner or later....the barriers between circumstances of oneself and of the rest of the world have broken down... after all that schooling, all that care. The separate essays build a braided narrative of a young woman grappling with pain in a degraded world. The collection mourns past and future loss, and explores types of insurance we have against suffering

Instability and spatiotemporal rheochaos in a shear-thickening fluid model

We model a shear-thickening fluid that combines a tendency to form inhomogeneous, shear-banded flows with a slow relaxational dynamics for fluid microstructure. The interplay between these factors gives rich dynamics, with periodic regimes (oscillating bands, travelling bands, and more complex oscillations) and spatiotemporal rheochaos. These phenomena, arising from constitutive nonlinearity not inertia, can occur even when the steady-state flow curve is monotonic. Our model also shows rheochaos in a low-dimensional truncation where sharply defined shear bands cannot form

Goal Development in Parents of Children with Epilepsy and Learning Disorders

poster abstractEpilepsy is the most common, chronic neurological condition in children, impacting 2.4 children per 1,000. Caregivers of children with epilepsy and learning disorders are affected by many confounding factors including complex drug regimens, navigating a complex healthcare system, the uncertainty of their child’s future and the challenge of creating an effective educational program in conjunction with their child’s school. Parents of children with epilepsy and learning disorders participated in the Creating Avenues for Parent Partnerships (CAPP) program. The original study was an experimental design in which parents were randomly placed in an intervention group or a wait list control group. Each group consisted of 25 parents, with a total of 50 parents participating in the pilot test of CAPP. One of the instruments that the parents completed throughout the duration of this interventional program was the Goal Attainment Scale (GAS). In the GAS, parents described their goals related to their child’s condition and care. Using a qualitative and systematic coding system the parent’s goals were categorized based on content and outcomes related to their child. The goals created by parents in this population subset fell into eight distinct categories. The categories discerned during analysis were future oriented, internal/perspective adjustment, interpersonal, maintaining normalcy, education/coordination with schools, interaction with health care professionals, physical fitness, and acknowledgement/fostering independence.. Based on analysis of the goals that parents created within the GAS, parents of children with epilepsy are particularly concerned with the security of their child’s future (both residentially and vocationally), educational advancement in partnership with schools, and improving health status through interaction with health care professionals. For the nurse interacting with patients and their caregiver in this specialized population it is critical to understand the goals that caregivers create in relation to the problems that they perceive as the most significant in their lives. Then the nurse will be able to enable caregivers to meet their goals and improve the health outcomes and overall quality of life in children with epilepsy and learning disorders

How the asymmetry of internal potential influences the shape of I-V characteristic of nanochannels

Ion transport in biological and synthetic nanochannels is characterized by such phenomena as ion current fluctuations, rectification, and pumping. Recently, it has been shown that the nanofabricated synthetic pores could be considered as analogous to biological channels with respect to their transport characteristics \cite{Apel, Siwy}. The ion current rectification is analyzed. Ion transport through cylindrical nanopores is described by the Smoluchowski equation. The model is considering the symmetric nanopore with asymmetric charge distribution. In this model, the current rectification in asymmetrically charged nanochannels shows a diode-like shape of $I-V$ characteristic. It is shown that this feature may be induced by the coupling between the degree of asymmetry and the depth of internal electric potential well. The role of concentration gradient is discussed

Grown organic matter as a fuel raw material resource

An extensive search was made on biomass production from the standpoint of climatic zones, water, nutrients, costs and energy requirements for many species. No exotic species were uncovered that gave hope for a bonanza of biomass production under culture, location, and management markedly different from those of existing agricultural concepts. A simulation analysis of biomass production was carried out for six species using conventional production methods, including their production costs and energy requirements. These estimates were compared with data on food, fiber, and feed production. The alternative possibility of using residues from food, feed, or lumber was evaluated. It was concluded that great doubt must be cast on the feasibility of producing grown organic matter for fuel, in competition with food, feed, or fiber. The feasibility of collecting residues may be nearer, but the competition for the residues for return to the soil or cellulosic production is formidable