Impact of host plant species and whitefly species on feeding behavior of Bemisia tabaci

Open Access JournalWhiteflies of the Bemisia tabaci species complex are economically important pests of cassava. In Africa, they cause greatest damage through vectoring viruses responsible for cassava mosaic disease and cassava brown streak disease. Several cryptic species from the B. tabaci complex colonize cassava and neighboring crops, but the feeding interactions between the different crops and B. tabaci species are unknown. The electrical penetration graph (EPG) technique makes it possible to conduct detailed feeding studies of sap-sucking insects by creating an electric circuit through the insect and the plant. The apparatus measures the voltage fluctuations while the wired-up insect feeds and produces graphs that describe feeding behavior. We utilized EPG to explore the feeding behavior of cassava-colonizing whiteflies (SSA1-SG3) on cassava, sweet potato, tomato, and cotton; and sweet potato-colonizing whiteflies (MED and IO) on cassava and sweet potato. Results show that: (1) feeding of SSA1-SG3 is not restricted to cassava. The least preferred host for SSA1-SG3 was tomato, where probing was delayed by 99 min compared to 10 min on other hosts, furthermore mean duration of phloem ingestion events was 36 min compared to 260 min on cassava. (2) Feeding of MED on cassava appeared to be non-functional, as it was characterized by short total phloem ingestion periods (5 h). (3) Wire diameter affects the feeding in a statistically and practically significant manner. Implications for whitefly control and studies of host whitefly resistance are discussed

Listening to our stories in dusty boxes: Indigenous storytelling methodology, archival practice, and the Cherokee Female Seminary

Influenced by a drive to seek out interdisciplinary connections within Rhetoric and Composition and to put these intersections into practice, this dissertation seeks out the ways indigenous ways of knowing, such as storytelling, can provide a heuristic to understand the ways our dappled discipline works to create community-based knowledges, and how these knowledges sustained through storytelling can recover the histories in our discipline by opening up our boundaries framed by dominant origin stories. Building on the work of decolonial and indigenous scholars, this dissertation asserts that indigenous storytelling encourages researchers to re-tool dominant methods in existing colonial structures in order to do the work of knowledge-making that more easily includes posthuman practices alongside distinctively human ones. Using the Cherokee Female Seminary during the nineteenth century as a case for this kind of methodology, storytelling uncovers and builds relationships through participatory means, contextualizing both the human and non-human agents in archival work that can work to decenter the discipline by using knowledge-making through storytelling as an active, balancing force. The result is revisionist history, but it’s also a returning present reality--the reality that these archives have always already been indigenous even in a colonized state, the reality that our research methodology need to navigate colonial structures still present, and the reality we, as scholars, must seek reflective practices that are vigilant against our own cultural ecologies. While enriching historiographic work in Rhetoric and Composition, the storytelling in this dissertation develops interdisciplinary themes in knowledge-making practices that are indigenous, rhetorical, posthuman, and ecological, and can be applied to research methodologies in professional writing, digital rhetorics, and historiography

A Call to Love: Campus Climate Concerning Individuals with Same-Sex Attraction

This study investigates the impact of campus climate concerning students with same-sex attraction at Southeastern University. The current study surveyed Southeastern undergraduate and graduate students in regards to the perceived attitudes on campus toward students with same-sex attraction (SSA). The major concern was to identify the majority attitude of administrators, faculty, staff, and students pertaining to the treatment of this sexual minority on campus by these particular groups and in major areas of the campus, such as the classroom, athletics, and chapel. This study also allotted the latter half of the survey to an anonymous questionnaire for students who identify as bisexual or homosexual. This section inquired on these students’ demographics concerning their SSA and allowed for open-ended responses for students to express their feelings concerning campus climate, their Christian walk, and how the university could better assist students who struggle and/or identify with this sexual minority

How do national health guidelines work? A realist analysis of the ACC Moving and Handling People New Zealand Guidelines, 2012

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Direct Measurement of the X-ray Time-Delay Transfer Function in Active Galactic Nuclei

The origin of the observed time lags, in nearby active galactic nuclei (AGN), between hard and soft X-ray photons is investigated using new XMM-Newton data for the narrow-line Seyfert I galaxy Ark 564 and existing data for 1H0707-495 and NGC 4051. These AGN have highly variable X-ray light curves that contain frequent, high peaks of emission. The averaged light curve of the peaks is directly measured from the time series, and it is shown that (i) peaks occur at the same time, within the measurement uncertainties, at all X-ray energies, and (ii) there exists a substantial tail of excess emission at hard X-ray energies, which is delayed with respect to the time of the main peak, and is particularly prominent in Ark 564. Observation (i) rules out that the observed lags are caused by Comptonization time delays and disfavors a simple model of propagating fluctuations on the accretion disk. Observation (ii) is consistent with time lags caused by Compton-scattering reverberation from material a few thousand light-seconds from the primary X-ray source. The power spectral density and the frequency-dependent phase lags of the peak light curves are consistent with those of the full time series. There is evidence for non-stationarity in the Ark 564 time series in both the Fourier and peaks analyses. A sharp `negative' lag (variations at hard photon energies lead soft photon energies) observed in Ark 564 appears to be generated by the shape of the hard-band transfer function and does not arise from soft-band reflection of X-rays. These results reinforce the evidence for the existence of X-ray reverberation in type I AGN, which requires that these AGN are significantly affected by scattering from circumnuclear material a few tens or hundreds of gravitational radii in extent.Comment: Accepted for publication in Ap

Use of Guidance Material for Moving and Handling People: Barriers and Facilitators - An Experience Exchange

Presentation of the research project and preliminary findings of questionnaire survey as introduction to a work shop for people interested in improving health and safety related to moving and handling people