Spraying to prevent fruit formation on certain shade and ornamental trees.

Thesis (M.S.

Acoustic Nondestructive Evaluation of Energy Release Rates in Plane Cracked Solids

Acoustic measurements, using longitudinal waves in plane specimens, based on the theory of acoustoelasticity, permit the determination of the sum of the principal stresses (σl + σ2). By automatic scanning, we are able to make such measurements throughout a region of interest. In this paper we shall be concerned with the application of this acoustoelastic stress analysis to fracture mechanics. Specifically, the energy release rates for extension and rotation of a crack will be determined experimentally (J integral for extension, L integral for rotation) followed by a numerical adjustment procedure which may be called the rescaling technique. If desired the stress intensity factors at a crack tip may also be evaluated. This procedure was applied to three different specimen configuratlons, and the results compare favorably with purely theoretical predictions

The Use of Acoustoelastic Measurements to Characterize the Stress States in Cracked Solids

The theory of acoustoelasticity predicts that a plane longitudinal acoustic wave passing through a solid which is already in a deformed state will propagate with a velocity (v) which is different from the (v0) of the same wave propagating through the undeformed medium. It may be shown that Δv/v0 = (v-v0)/v0 = B(σ1+σ2) where σ1 and σ2 are the principal stress in the plane normal to the wave propagation direction and B is the acoustoelastic constant. Wave transit time measurements allow the relative velocity change Δv/v0 to be determined, so that contours of constant principal stress sum (σ1+σ2) may be mapped by acoustically scanning a stressed solid. We have used the technique described above to characterize the states of stress in cracked and notched aluminum panels. A method for extracting crack stress intensity factors from the acoustic data is proposed and illustrated for center-cracked panel specimens. The results indicate that the technique may offer a promising method for nondestructive testing and evaluation

Educational Research and Developing Countries; facts, figures and some conceptual approaches for analysing interactions between funding, products and users

SUMMARY Educational research in the development context (ERDC) is the product of various kinds of international interactions and negotiations. These provide a typology of such research: disciplinary, instrumental, action, and policy research. All these are characterised by particular patterns of information flow and are influenced by resource availability and power structures. Suggestions for reforming ERDC are put forward. RESUMEN Investigación en educación y países en desarrollo: hechos, cifras y algunos enfoques conceptuales para analizar las interacciones existentes entre financiamiento, resultados y usuarios La investigación educacional en el contexto del desarrollo es resultado de variadas interacciones y negociaciones internacionales, las que le proporcionan una tipología; disciplina, instrumental, acción y política. Todas estas categorías están caracterizadas por determinados flujos informativos e influenciadas por la disponibilidad de recursos y las estructuras de poder. Se formulan sugerencias para reformarla. SOMMAIRE La recherche sur l'éducation et les pays en voie de développement: faits, chiffres, et quelques approches conceptuelles pour l'analyse des interactions entre le financement, les produits et les utilisateurs La recherche sur l'éducation dans le contexte du développement (RECD) est le résultat de différentes sortes d'interactions et de négotiations internationales. Elles donnent une typologie d'une telle recherche: disciplinaire, instrumentale, action, et politique de recherche. Elles sont toutes caractérisées par des formes particulières de courant d'information et sont influencées par la disponibilité des ressources et les structures de compétence Des suggestions en vue de faire des réformes dans la RECD sont énoncées

Readability of COVID-19 Parental Guidance Documents

The purpose of this study is to examine the readability levels of the state departments of education guidance documents regarding COVID-19 protocols for families of students receiving special education services. The authors searched the 50 states and the District of Columbia’s departments of education websites for their COVID-19, special education, parental guidance documents for the 2020-2021 school year. Parental guidance documents were available from 90% (46/51) of the department of education websites with 61% (31/51) of those documents specifically designed for parents of children receiving special education services. The researchers used the Flesch Reading Ease (FRES) to analyze the reading level of the 31 documents that the departments of education websites created for families of individuals receiving special education services. The FRES score was 43.05, indicating that the average reading difficulty was “difficult” with a “college reading level.” The Flesch-Kincaid Grade Level (FKGL) average score for the reviewed documents revealed an average U.S. grade level of 12.34. Thus, documents produced during the COVID-19 pandemic significantly exceeded the appropriate reading level recommended by the current research (Nagro & Stein, 2016). To improve communication and provide caregivers with the necessary information to make informed decisions regarding their children’s educational need during the COVID-19 pandemic, it is essential for parental guidance documents to be written at lower reading levels to accommodate the general population

Noncommutative resolutions of ADE fibered Calabi-Yau threefolds

In this paper we construct noncommutative resolutions of a certain class of Calabi-Yau threefolds studied by F. Cachazo, S. Katz and C. Vafa. The threefolds under consideration are fibered over a complex plane with the fibers being deformed Kleinian singularities. The construction is in terms of a noncommutative algebra introduced by V. Ginzburg, which we call the "N=1 ADE quiver algebra"

Captive reptile mortality rates in the home and implications for the wildlife trade

The trade in wildlife and keeping of exotic pets is subject to varying levels of national and international regulation and is a topic often attracting controversy. Reptiles are popular exotic pets and comprise a substantial component of the live animal trade. High mortality of traded animals raises welfare concerns, and also has implications for conservation if collection from the wild is required to meet demand. Mortality of reptiles can occur at any stage of the trade chain from collector to consumer. However, there is limited information on mortality rates of reptiles across trade chains, particularly amongst final consumers in the home. We investigated mortality rates of reptiles amongst consumers using a specialised technique for asking sensitive questions, additive Randomised Response Technique (aRRT), as well as direct questioning (DQ). Overall, 3.6% of snakes, chelonians and lizards died within one year of acquisition. Boas and pythons had the lowest reported mortality rates of 1.9% and chameleons had the highest at 28.2%. More than 97% of snakes, 87% of lizards and 69% of chelonians acquired by respondents over five years were reported to be captive bred and results suggest that mortality rates may be lowest for captive bred individuals. Estimates of mortality from aRRT and DQ did not differ significantly which is in line with our findings that respondents did not find questions about reptile mortality to be sensitive. This research suggests that captive reptile mortality in the home is rather low, and identifies those taxa where further effort could be made to reduce mortality rate

HIV genotypic resistance among pregnant women initiating ART in Uganda: a baseline evaluation of participants in the Option B+ clinical trial

Background: Pre-treatment HIV drug resistance is a threat to elimination of mother to child HIV transmission and could lead to virological failure among HIV-positive pregnant women. We analysed genotypic HIV drug resistance (HIVDR) of baseline samples of participants enrolled in the Option B+ clinical trial in Uganda.Methods: HIV-infected pregnant women attending antenatal care were enrolled from Uganda’s National Referral Hospital (Mulago) and Mityana District general hospital and surrounding health centers (HCs). Genotypic HIV testing was performed on blood samples from the first 135 enrolled women out of a subset of 136 participants (25%) who had a baseline VL>1000 copies/mL as one sample failed to amplify.Results: 159/540 (29.4%) had a VL < 1000 copies/ml and 381/540 (70.6%) had a VL >1,000 copies/ml. Of the women with VL>1000 copies/ml, 32 (23.7%) had resistance mutations including 29/135 (21.5%) NNRTI mutations, 6/135 (4.4%) NRTI mutations and 3/135 (2.2%) had both NNRTI and NRTI mutations. The most common NNRTI resistance mutations were: K103KN (5), K103N (5), V179T (4) and E138A (4).Conclusions: One quarter of the HIV-infected pregnant women in this trial at baseline had NNRTI genotypic resistance mutations. Our findings support new WHO guidelines for first-line ART that were changed to dolutegravir-based regimens