Pulsed electron beam induced recrystallization and damage in GaAs

Single-pulse electron-beam irradiations of 300-keV 10^(15)Kr+/cm^2 or 300-keV 3×10^(12)Se+/cm^2 implanted layers in unencapsulated GaAs are studied as a function of the electron beam fluence. The electron beam pulse had a mean electron energy of ~-20 keV and a time duration of ~-10^(–7) s. Analyses by means of MeV He + channeling and TEM show the existence of narrow fluence window (0.4–0.7 J/cm^2) within which amorphous layers can be sucessfully recrystallized, presumably in the liquid phase regime. Too high a fluence produces extensive deep damage and loss of As

Positive surface charge of GluN1 N-terminus mediates the direct interaction with EphB2 and NMDAR mobility.

Localization of the N-methyl-D-aspartate type glutamate receptor (NMDAR) to dendritic spines is essential for excitatory synaptic transmission and plasticity. Rather than remaining trapped at synaptic sites, NMDA receptors undergo constant cycling into and out of the postsynaptic density. Receptor movement is constrained by protein-protein interactions with both the intracellular and extracellular domains of the NMDAR. The role of extracellular interactions on the mobility of the NMDAR is poorly understood. Here we demonstrate that the positive surface charge of the hinge region of the N-terminal domain in the GluN1 subunit of the NMDAR is required to maintain NMDARs at dendritic spine synapses and mediates the direct extracellular interaction with a negatively charged phospho-tyrosine on the receptor tyrosine kinase EphB2. Loss of the EphB-NMDAR interaction by either mutating GluN1 or knocking down endogenous EphB2 increases NMDAR mobility. These findings begin to define a mechanism for extracellular interactions mediated by charged domains

Online Finance And Economics Courses: A Comparative Study Of Course Satisfaction And Outcomes Across Learning Models

Student learning outcomes and course satisfaction scores are two key considerations when assessing the success of any degree program.  This empirical study was based upon more than 3,000 end-of-semester course evaluations collected from 171 courses in the 2010-2011 academic year.  The study, conducted at a Midwestern business college, considered the model of learning when examining course satisfaction scores of finance and economics courses.  The finance and economics courses at the college all use active learning constructs, even in the online and blended course models.  Online, blended and face-to-face courses were studied to determine whether there was a statistically significant difference between course satisfaction and any of the models of learning.  Surprisingly, online and blended courses had a stronger relationship with high course satisfaction than did face-to-face courses.  The average grade point average of each course was also correlated with the three learning models, seeking a relationship between learning outcomes and online, blended and face-to-face courses.  There was no significant relationship found among student learning outcomes, as demonstrated by grade point average, and model of learning, indicating that students were able to achieve the same outcomes despite model of learning chosen

Encouraging return migration and population retention in rural communities

"This publication was supported by partner contributions from The Community Foundation of Northwest Missouri’s Maximize NWMO Regional Vitality Initiative. Funding for this publication’s analysis is from University of Missouri Extension with long-term support from the U.S. Department of Agriculture’s National Institute for Food and Agriculture."--Page 2.stats202303upload"This publication highlights findings from a recent MU Extension study that investigated attitudes on rural living preferences among northwest Missouri residents. Rural leaders in the study region provided the impetus for this investigation as they sought to receive input on how to attract newly footloose workers. The study found that motivators for migration to rural areas include social ties, community attachment and employment opportunities. Understanding motivating factors for migration helps guide community leaders in proactively attracting and retaining new residents to depopulating, low-amenity rural areas. Additionally, insights can be leveraged by policymakers as they encourage population retention and growth in rural communities."--First page.Written by Mallory L. Rahe (Associate Extension Professor, Division of Applied Social Sciences), TaylorAnn Washburn (Program Coordinator, Division of Applied Social Sciences)New 1/2023Includes bibliographical reference

Steady-state thermally annealed GaAs with room-temperature-implanted Si

Semi-insulating Cr-doped single-crystal GaAs samples were implanted at room temperature with 300-keV Si ions in the dose range of (0.17–2.0)×1015 cm–2 and were subsequently steady-state annealed at 900 and 950°C for 30 min in a H2 ambient with a Si3N4 coating. Differential Hall measurements showed that an upper threshold of about 2×1018/cm3 exists for the free-electron concentration. The as-implanted atomic-Si profile measured by SIMS follows the theoretical prediction, but is altered during annealing. The Cr distribution also changes, and a band of dislocation loops ~2–3 kÅ wide is revealed by cross-sectional TEM at a mean depth of Rp~3 kÅ. Incomplete electrical activation of the Si is shown to be the primary cause for the effect

Is Razor-wire an Effective Deterrent for Birds Perching on Security Fences at Airports?

Wildlife-aircraft collisions (wildlife strikes) pose a serious risk to aircraft and cost civil aviation in the United States an estimated $957 million annually. Blackbirds and doves in particular have caused some of the most devastating aircraft accidents related to wildlife strikes in the United States and Europe. Birds perching on security fences and other structures are a problem at airports and other locations where birds are not desired. Reduction of available perching sites should make airports less attractive to these species and thus reduce the risk of damaging wildlife strikes. We conducted a series of experiments to determine if 3 species of birds hazardous to aviation [i.e., mourning doves (Zenaida macroura), common grackles (Quiscalus quiscula), and brown-headed cowbirds (Molothrus atar)] were deterred from perching sites at the top of a 3-stranded security fence by the application of Razor–ribbon™ Helical razor-wire. We determined bird use (for perching) of 3-stranded barbed wire security fences, with and without the addition of razor-wire using 6 birds each in 2 3.6- x 8.5- x 2.4-m flight cages. Treatment perches consisted of the top portion of a 3-stranded barbed wire security fence (2.5-m in length) with 2.5-m of razor-wire attached. Control perches consisted of an identical portion of security fence without the razor-wire. During the experimental period, mourning doves were observed on razor-wire protected fences twice as often, brown-headed cowbirds were observed similar amounts of time, and common grackles were observed 4 times as often as they were on unprotected fences. We found no evidence that razor-wire provided any deterrence to birds that perch on security fences

Wildlife in Airport Environments: Chapter 8 Identification and Management of Wildlife Food Resources at Airports

Wildlife use airport habitats for a variety of reasons, including breeding, raising young, resting, taking refuge from predators, and locating sources of water. But the chief motivation for most individuals to encroach on airports is food. Depending on the specific habitat types present and habitat management strategies employed, airports can harbor large numbers of small mammals, insects, earthworms, and palatable vegetation that attract many species hazardous to aircraft. Often the best way to reduce populations of hazardous wildlife at airports is to determine which sources of food are being used, and then remove or modify those foods to make them less attractive (Washburn et al. 2011). Fortunately, the science of wildlife ecology and management has a long and productive history of research on wildlife food habits and foraging strategies, and the applied nature of most food habit studies conducted in airport environments facilitates straightforward specialization of investigational techniques. In this chapter we (1) discuss in more detail food resources as a primary motivation for wildlife use of airport properties, (2) consider some established principles of wildlife food habits and foraging strategies that affect airport wildlife management, (3) review techniques used to investigate wildlife food habits and identify those most useful for airports, (4) discuss methods for eliminating or modifying some preferred foods at airports, and (5) briefly consider future research needs

The value of visual fields in the diagnosis of focal and oral infections

The value of visual fields in the diagnosis of focal and oral infection

General Order Number 13, April 1861

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