Considerations of electron beam propagation from space vehicles

Theoretical analysis of electron beam array propagation from spacecraf

Design of a Physical Windkessel Model for Use in LVAD In-vitro Benchtop Modeling

Despite improved life expectancy compared to medical management alone, Ventricular Assist Device (VAD) recipients show survival rates of 80% at 12 months and 70% at 24 months. A large portion of VAD-associated mortality results from increased risk of stroke with an event frequency reported between 14-47%. Recent concerns have been raised about unprecedented increases of thrombus formation in VAD recipients with subsequent reports pointing towards implantation techniques as a critical contributor to these events. Thus, the overall prognosis with mechanical support can improve by advancing the surgeon’s approach to VAD implantation. Previous studies using Computational Fluid Dynamics (CFD) were aimed at reducing stroke rates by tailoring the VAD outflow graft (VAD-OG) angle to direct any circulating emboli away from the cerebral vessels. In-vitro, or benchtop, models are often developed as computational counterparts. In order to accurately model the hemodynamics in the cardiovascular system, pulsatile flow must be mimicked. This is achieved in the computational domain by what is called a Windkessel model. This project seeks to develop a physical analogy to the Windkessel model for use in the benchtop experiments

Radiation testing of composite materials, in situ versus ex situ effects

The effect of post irradiation test environments on tensile properties of representative advanced composite materials (T300/5208, T300/934, C6000/P1700) was investigated. Four ply (+ or - 45 deg/+ or - 45 deg) laminate tensile specimens were exposed in vacuum up to a bulk dose of 1 x 10 to the 10th power rads using a mono-energetic fluence of 700 keV electrons from a Van de Graaff accelerator. Post irradiation testing was performed while specimens were being irradiated (in situ data), in vacuum after cessation of irradiation (in vacuo data), and after exposure to air (ex situ data). Room temperature and elevated temperature effects were evaluated. The radiation induced changes to the tensile properties were small. Since the absolute changes in tensile properties were small, the existance of a post irradiation test environment effect was indeterminate

Finite difference time domain modeling of spiral antennas

The objectives outlined in the original proposal for this project were to create a well-documented computer analysis model based on the finite-difference, time-domain (FDTD) method that would be capable of computing antenna impedance, far-zone radiation patterns, and radar cross-section (RCS). The ability to model a variety of penetrable materials in addition to conductors is also desired. The spiral antennas under study by this project meet these requirements since they are constructed of slots cut into conducting surfaces which are backed by dielectric materials

Electron accelerator for Aerobee 350 rocket - Description, development and flight performance Final report

Aerobee-borne electron accelerators for ejecting electron beams into upper atmospher

Carbon fiber plume sampling for large scale fire tests at Dugway Proving Ground

Carbon fiber sampling instruments were developed: passive collectors made of sticky bridal veil mesh, and active instruments using a light emitting diode (LED) source. These instruments measured the number or number rate of carbon fibers released from carbon/graphite composite material when the material was burned in a 10.7 m (35 ft) dia JP-4 pool fire for approximately 20 minutes. The instruments were placed in an array suspended from a 305 m by 305 m (1000 ft by 1000 ft) Jacob's Ladder net held vertically aloft by balloons and oriented crosswind approximately 140 meters downwind of the pool fire. Three tests were conducted during which released carbon fiber data were acquired. These data were reduced and analyzed to obtain the characteristics of the released fibers including their spatial and size distributions and estimates of the number and total mass of fibers released. The results of the data analyses showed that 2.5 to 3.5 x 10 to the 8th power single carbon fibers were released during the 20 minute burn of 30 to 50 kg mass of initial, unburned carbon fiber material. The mass released as single carbon fibers was estimated to be between 0.1 and 0.2% of the initial, unburned fiber mass

Sublime Microglia: Expanding Roles for the Guardians of the CNS

Recent findings challenge the concept that microglia solely function in disease states in the central nervous system (CNS). Rather than simply reacting to CNS injury, infection, or pathology, emerging lines of evidence indicate that microglia sculpt the structure of the CNS, refine neuronal circuitry and network connectivity, and contribute to plasticity. These physiological functions of microglia in the normal CNS begin during development and persist into maturity. Here, we develop a conceptual framework for functions of microglia beyond neuroinflammation and discuss the rich repertoire of signaling and communication motifs in microglia that are critical both in pathology and for the normal physiology of the CNS

The Third Wave of Educational Reform: Fostering the Development of the Whole Child

The third wave of educational reform goes beyond narrowly focusing on student achievement (first wave) to also recognizing the need for social-emotional learning (second wave), and now including wraparound services for health, safety, and family/community engagement to equitably meet the holistic needs of all students, especially those in poverty. Contributing to the third wave, the “5H” Holistic Framework (5HHF) provides five protective/promotive factors to meet students’ needs and promote their holistic well-being: Head (academic achievement), Heart (social-emotional care), Hand (safety/security), Health (physical/mental health), and Home (family/community engagement). We will introduce educators to current vocabulary, processes for gathering student voice, a readiness inventory, an assessment rubric, a whole school improvement template, and funding opportunities needed to turn the 5HHF into action

Event-driven simulations of a plastic, spiking neural network

We consider a fully-connected network of leaky integrate-and-fire neurons with spike-timing-dependent plasticity. The plasticity is controlled by a parameter representing the expected weight of a synapse between neurons that are firing randomly with the same mean frequency. For low values of the plasticity parameter, the activities of the system are dominated by noise, while large values of the plasticity parameter lead to self-sustaining activity in the network. We perform event-driven simulations on finite-size networks with up to 128 neurons to find the stationary synaptic weight conformations for different values of the plasticity parameter. In both the low and high activity regimes, the synaptic weights are narrowly distributed around the plasticity parameter value consistent with the predictions of mean-field theory. However, the distribution broadens in the transition region between the two regimes, representing emergent network structures. Using a pseudophysical approach for visualization, we show that the emergent structures are of "path" or "hub" type, observed at different values of the plasticity parameter in the transition region.Comment: 9 pages, 6 figure

Microglial phagocytosis mediates long-term restructuring of spinal GABAergic circuits following early life injury

Peripheral injury during the early postnatal period alters the somatosensory system, leading to behavioural hyperalgesia upon re-injury in adulthood. Spinal microglia have been implicated as the cellular mediators of this phenomenon, but the mechanism is unclear. We hypothesised that neonatal injury (1) alters microglial phagocytosis of synapses in the dorsal horn leading to long-term structural changes in neurons, and/or (2) trains microglia, leading to a stronger microglial response after re-injury in adulthood. Using hindpaw surgical incision as a model we showed that microglial density and phagocytosis increased in the dorsal horn region innervated by the hindpaw. Dorsal horn microglia increased engulfment of synapses following injury, with a preference for those expressing the vesicular GABA transporter VGAT and primary afferent A-fibre terminals in neonates. This led to a long-term reduction of VGAT density in the dorsal horn and reduced microglial phagocytosis of VGLUT2 terminals. We also saw an increase in apoptosis following neonatal injury, which was not limited to the dorsal horn suggesting that larger circuit wide changes are happening. In adults, hindpaw incision increased microglial engulfment of predominantly VGAT synapses but did not alter the engulfment of A-fibres. This engulfment was not affected by prior neonatal injury, suggesting that microglial phagocytosis was not trained. These results highlight microglial phagocytosis in the dorsal horn as an important physiological response towards peripheral injury with potential long-term consequences and reveals differences in microglial responses between neonates and adults