Graduate Student Papers

Permanent URI for this collection

https://hdl.handle.net/10919/91467

Browse

Now showing 1 - 20 of 107

Campylobacter jejuni - An emerging foodborne pathogen
Altekruse, Sean Fitzgerald; Stern, N. J.; Fields, P. I.; Swerdlow, David L. (1999-01)
Campylobacter jejuni is the most commonly reported bacterial cause of foodborne infection in the United States. Adding to the human and economic costs are chronic sequelae associated with C. jejuni infection-Guillain-Barre syndrome and reactive arthritis. In addition, an increasing proportion of human infections caused by C. jejuni are resistant to antimicrobial therapy. Mishandling of raw poultry and consumption of undercooked poultry are the major risk factors for human campylobacteriosis. Efforts to prevent human illness are needed throughout each link in the food chain.
Rawls and capabilities: the current debate [draft]
D'Amato, Claudio (Virginia Tech, 2014)
The capability approach to justice was con-ceived as an alternative to the Rawlsian scholar-ship that became dominant in moral and political philosophy at the end of the XX century. Among other issues, capability theorists have objected to Rawls’s identification of the currency of distribu-tive justice with primary goods and to the claim that the appropriate subject of distributive justice is the basic structure of society. As Ingrid Robeyns (2011) puts it, capability theorists argue that capability as a “metric of justice” does a better job than Rawlsian primary goods at capturing what human beings seek in a social distributive scheme. How-ever, the relation between the two sides of the debate is not one of stark opposition, but rather one of productive exchange: all work within the liberal political tradition, and in the last few years there has been considerable mutual understanding, co-operation, and a certain softening of the two sides’ original positions—pun intended. This paper surveys the main arguments in the debate and evaluates recent (2003-2013) contributions to the literature that attempt to bridge the gap between justice as fairness and the capability approach.
The road to moral independence: agency, gender, and family in The Last of Us [draft]
D'Amato, Claudio (Virginia Tech, 2014)
... The Last of Us (TLOU) is one of the most literary games of the modern era, and my personal favorite in a long time, perhaps since the equally well-written Mass Effect 2. It is ripe with moral dilemmas and psychologically fascinating characters, and it allows players and critics to discuss gender roles at a con-ceptual depth seldom seen in the video game industry. Much has been said in the popular press about whether the game is fundamentally sexist with some redeeming qualities or fundamentally feminist with some dark spots. It is in fact both. From a purely critical standpoint, it is a sharp, at times virulent, critique of patriarchal gender roles. But its critique is too understated, and most players will be unable to see it and will risk mistaking villains for heroes and sexism for equality. TLOU is the best possible game that could have been written given its constraints, but it could have made its feminist point—which it does have, and which is extremely good—much better.
Quantum mechanics students' understanding of normalization
Watson, Kevin Lee (2017)
Normalization is a particularly important concept within quantum mechanics due to the probabilistic nature of quantum systems. However, students' understanding of normalization has not been an explicit focus in past studies. In this paper, I will present a preliminary framework for students' understanding of mathematical norms and normalization of vectors, using interviews with quantum mechanics students to illustrate how the framework can be used to model and make sense of students' reasoning about the normalization of vectors.
Gender Perception on the Health and Environmental Hazards of Pesticide Usage among Cocoa Farmers in Ekiti State, Nigeria
Olowoyo, Olamide; Fasilat, Deji Olanike (Science Publishing Group, 2017)
The study was conducted in Ekiti State, Nigeria among male and female cocoa farmers, to assess the gender differential in perception of the health and environmental hazards of pesticides usage. Multi stage purposive sampling technique was used to select 120 male cocoa farmers and 120 female cocoa farmers to make a total of 240 respondents for the study. Descriptive and inferential statistics was used to analyse the data. The result showed that male cocoa farmers, likewise female cocoa are vulnerable to health, (tearing and redness of eyes, body pain, headache) hazards, likewise they also indicated their experience of environmental (air pollution, pollute streams) hazards. About 64% Male and 54% female cocoa farmers had a positive perception of the health and environmental hazards of pesticides usage but there was a significant difference between male and female cocoa farmers perception of pesticides hazards. It was concluded that majority male as well as female cocoa farmers in Ekiti State were vulnerable to one pesticide hazards or the other. Adequate and frequent training was recommended for male and female cocoa farmers on pesticides hazards, at the same time less reliance on pesticides usage to reduce vulnerability to the hazards.
Gender Analysis of Factors Influencing Soil and Water Conservation Technology Utilization among Vegetable Farmers in Ekiti and Oyo States, Nigeria
Faniyi, Ebunoluwa; Deji, Olanike; Olowoyo, Olamide; Sulaimon, Waheed; Aduwo, Oluwafunke (Nigerian Journal of Rural Sociology, 2019)
The study assessed the gender analysis of factors associated with soil and water conservation technology usage among vegetable farmers in Ekiti and Oyo States, Nigeria. It specifically, described the socioeconomic characteristics of vegetable farmers and examined the gender-specific factors associated with soil and water conservation technology utilisation in vegetable production. The study adopted a multi-stage sampling procedure. Data were elicited from the respondents using an interview schedule and focus group discussion guide. The study used inferential and descriptive statistics to analyse the data from the survey. The findings showed that the mean age for male was 35 years and female vegetable farmers 41 years. While the mean years of vegetable farming experience for male was 16 years and female vegetable farmers was 19 years. Varimax factor rotation pattern was used to isolate six factors associated with soil and water conservation technology usage for male vegetable farmers, which were information-source factor (14.4%), family factor (14.0%), resources factor (11.7%), economic factor (10.5%), soil-fertility factor (8.3%), and institutional factor (8.0%). Also,five factors were isolated for the female vegetable which were include; personal-experience factor (21.6%), information source factor (20.0%), land acquisition factor (10.7%), resources factor (10.0%), and group membership factor (7.7%). Information, resources, economic, personal experience, and land acquisition were the gender-specific factors influencing soil water conservation (SWC) technology usage. It was recommended that the factors identified should be noted as springboard for technology development and dissemination in Nigeria, this will help in the removal of the existing gender gaps among the farmers, especially in the rural areas and ensure sustainable agricultural practices and rural transformation.
Gender Utilization of Forest Products among Rural Dwellers in Osun State, Nigeria
Sulaimon, Waheed Suberu; Deji, Olanike Fasilat; Olowoyo, Olamide; Faniyi, Ebunoluwa Oyindamola (2019)
This study specifically determined male and female’s level of utilization of forest products among rural dwellers in Osun State, Nigeria through the instrumentality of gender lens. Multi-stage sampling procedure was used in selecting a total of 240 respondents. Structured interview schedule and Focus Group Discussion Guide were used to collect quantitative and qualitative data. Data collected were analyzed using descriptive and inferential tools. The results show that the mean level of utilization of forest products for male respondents was 266.99±70.31, while that of female respondents was 248.23±72.04 (with a maximum obtainable score of 747). The results of t-test show that calculated t-value of 2.042 was higher than the critical t-value of 0.042 at p≤0.05 with 238 degrees of freedom. This result implies that there was a significant difference in the utilization of forest products by male and female respondents. The Focus Group Discussion results show that male respondents have favorable disposition in their utilization of economically viable forest products than females. This in turn has created a source of financial advantage through a robust economic engagement of males in the study area. However, females have always been at the receiving end of natural resource policies which tend to favor males at their detriment. This in turn has hindered sustainable utilization of forest products in the study area In conclusion; there was a significant difference in the level of utilization of forest products by male and female respondents. The result of this statistical analysis indicates that the calculated t-value of 2.042 is higher than the critical t-value of 0.042 at 0.05 level of significance with 238 degree of freedom. Hence, the study seeks attention in addressing this inequality by engendering policy frameworks which tends to focus on gender equality in order to ensure sustainable forest resource utilization as a panacea for economic development.
Gender Specific Factors Associated With Hazards of Pesticide Usage among Cocoa Farmers in Nigeria
Olowoyo, Olamide; Deji, Olanike Fasilat; Sulaimon, Waheed Suberu; Faniyi, Ebunoluwa Oyindamola (2019)
This study assessed the gender specific factors associated with health and environmental hazards of pesticide usage among cocoa farmers in Ekiti State, Nigeria a region known with predominance in cocoa production. It specifically described the socio-economic characteristics of male and female cocoa farmers and isolate factors associated with health and environmental hazards of pesticide usage in cocoa production. 120 male cocoa farmers and 120 female cocoa farmers were selected through multi stage purposive sampling technique in five local government areas of the state, to make a total of 240 respondents for the study. The study adopts the use of inferential and descriptive statistics to analyze the data from the survey. The mean age for male and female cocoa farmers was 52.5±9.82 and 45.2± 8.49 respectively while the mean years of cocoa farming experience for male and female cocoa farmers was 27.9±9.23 and 22.3±9.68 respectively. Varimax factor rotation pattern was used to isolate six factors associated with health and environmental hazards for male cocoa farmers which include: ‘information source factor’, ‘extension contact factor’, ‘experience factor’, ‘knowledge-pesticide usage factor’, ‘group membership factor’ and ‘family factor’ and six factors associated with health and environmental hazards for female cocoa farmers which include: ‘knowledge factor’, ‘information source factor’ ‘group membership factor’ ‘extension contact factor’ ‘family factor’ and ‘pesticide usage’ were isolated. Awareness of the gender specific factors to understanding hidden gender issues associated with hazards of pesticide usage among cocoa farmers was recommended. Hence, this is to ensure sustainable pesticide usage and to boost environmental productivity for rural development.
The EarthBox Project in Grayson County, Virginia
Cole, Kathy; Dobson, Liza (2019-03-16)
Deep Learning for Forest Plantation Mapping in Godavari Districts of Andhra Pradesh, India
More, Snehal; Karpatne, Anuj; Wynne, Randolph H.; Thomas, Valerie A. (Virginia Tech, 2019-08)
Small-area forest plantations play a vital role in the socioeconomic well-being of farmers in Southeast Asia. Most plantations are established on former agricultural land, often on land less suitable for agriculture. Plantations that are converted from natural forest have adverse impacts on biodiversity. Mapping small-area plantations is thus important to understand the dynamics of forest cover in Southeast Asia and to study the social, economic, and ecological effects of this important land cover and land use change. While the small size of forest plantations makes it difficult to detect them using moderate resolution satellite sensors, the problem is exacerbated by the high degree of mixing between plantations, surrounding vegetation, and other land covers, which often show variegated responses in satellite signals across space and time. In this paper, we study the problem of mapping small-area forest plantations in East and West Godavari districts of Andhra Pradesh, India using deep learning methods. Remotely sensed cloud-free data from the Harmonized Landsat Sentinel-2 S10 product were classified using a pixel-level neural network and training data labeled using a field-based survey in concert with expert aerial photo interpretation. We compare the performance of deep learning methods with a baseline random forest classifier in our study region of 21543 sq. km over a period of 3 years and analyze the differences in the results across land cover classes and seasons.
Endemicity of Yaws and Seroprevalence of Treponema pallidum Antibodies in Nonhuman Primates, Kenya
Zimmerman, Dawn M.; Hardgrove, Emily H.; von Fricken, Michael E.; Kamau, Joseph; Chai, Daniel; Mutura, Samson; Kivali, Velma; Hussein, Fatima; Ambala, Peris; Surmat, Andrea; Maina, Joseph G.; Knauf, Sascha (2019-11)
Human yaws has historically been endemic to Kenya, but current epidemiologic data are lacking. We report seroprevalence for Treponema pallidum antibodies in olive baboons (Papio anubis) and vervet monkeys (Chlorocebus pygerythrus) in Laikipia County, Kenya. Our results suggest endemicity of the yaws bacterium in monkeys, posing a possible zoonotic threat to humans.
Deer movement and resource selection during Hurricane Irma: implications for extreme climatic events and wildlife
Abernathy, Heather N.; Crawford, Daniel A.; Garrison, Elina P.; Chandler, R. B.; Conner, M. L.; Miller, K. B.; Cherry, Michael J. (Royal Society, 2019-11-19)
Extreme climatic events (ECEs) are increasing in frequency and intensity and this necessitates understanding their influence on organisms. Animal behaviour may mitigate the effects of ECEs, but field studies are rare because ECEs are infrequent and unpredictable. Hurricane Irma made landfall in southwestern Florida where we were monitoring white-tailed deer (Odocoileus virginianus seminolus) with GPS collars. We report on an opportunistic case study of behavioural responses exhibited by a large mammal during an ECE, mitigation strategies for reducing the severity of the ECE effects, and the demographic effect of the ECE based on known-fate of individual animals. Deer altered resource selection by selecting higher elevation pine and hardwood forests and avoiding marshes. Most deer left their home ranges during Hurricane Irma, and the probability of leaving was inversely related to home range area. Movement rates increased the day of the storm, and no mortality was attributed to Hurricane Irma. We suggest deer mobility and refuge habitat allowed deer to behaviourally mitigate the negative effects of the storm, and ultimately, aid in survival. Our work contributes to the small but growing body of literature linking behavioural responses exhibited during ECEs to survival, which cumulatively will provide insight for predictions of a species resilience to ECEs and improve our understanding of how behavioural traits offset the negative impacts of global climate change.
Inequalities in Poverty and Income between Single Mothers and Fathers
Lu, Yuan-Chiao; Walker, Regine; Richard, Patrick; Younis, Mustafa (MDPI, 2019-12-24)
Background: The American family structure has changed in the past few decades due to a rise in the divorce rate and unmarried women with children. Research suggests a salary disparity between men and women, especially for those women after pregnancy. However, these studies were confined to individuals within traditional families, and there is a lack of information of income disparity and poverty status between single mothers and fathers. The current study explored the disparities in single-parent families based on the household income and the poverty status using a set of nationwide censor data. Methods: The current study used data from the 2011 and 2013 Panel Study of Income Dynamics (N = 1135). Multivariate regression models were used in the analysis. Results: The demographic characteristics of the weighted population showed that taxable income, total income, and poverty status were higher for single fathers than mothers, while non-work income was higher for single mothers than fathers. Single mothers were much more likely to be at the crisis category than single fathers. Multivariate analyses showed that gender, age, marital status, years of experience, and geographic region had effects on taxable income, and only gender, marital status, and region had effects on poverty status. Conclusions: The results suggest that vulnerable group of single mothers was acknowledged according to income and poverty status. Age, marital status, years of experience, and region would be the critical factors for predicting the income and poverty status for single parenthood.
Global Change Impacts Education Tool
Burke-Flask, Abby; Stark, Nina; Rodriguez-Marek, Adrian (Center for Geotechnical Practice and Research, 2020)
This presentation provides a broad overview of global change processes and impacts in coastal, permafrost, and inland regions. The presentation was developed to supplement a report for the Center for Geotechnical Practice and Research at Virginia Tech.
Nearest Neighbor Classifier – From Theory to Practice
Torfi, Amirsina (Machine Learning Mindset, 2020-01-11)
The K-nearest neighbors (KNNs) classifier or simply Nearest Neighbor Classifier is a kind of supervised machine learning algorithm that operates based on spatial distance measurements. In this article, we investigate the theory behind it. Furthermore, a working example of the k-nearest neighbor classifier will be represented.
Solution Blow Spinning of High-Performance Submicron Polyvinylidene Fluoride Fibres: Computational Fluid Mechanics Modelling and Experimental Results
Atif, Rasheed; Combrinck, Madeleine; Khaliq, Jibran; Hassanin, Ahmed H.; Shehata, Nader; Elnabawy, Eman; Shyha, Islam (MDPI, 2020-05-16)
Computational fluid dynamics (CFD) was used to investigate characteristics of high-speed air as it is expelled from a solution blow spinning (SBS) nozzle using a k-ε turbulence model. Air velocity, pressure, temperature, turbulent kinetic energy and density contours were generated and analysed in order to achieve an optimal attenuation force for fibre production. A bespoke convergent nozzle was used to produce polyvinylidene fluoride (PVDF) fibres at air pressures between 1 and 5 bar. The nozzle comprised of four parts: a polymer solution syringe holder, an air inlet, an air chamber, and a cap that covers the air chamber. A custom-built SBS setup was used to produce PVDF submicron fibres which were consequently analysed using scanning electron microscope (SEM) for their morphological features. Both theoretical and experimental observations showed that a higher air pressure (4 bar) is more suitable to achieve thin fibres of PVDF. However, fibre diameter increased at 5 bar and intertwined ropes of fibres were also observed.
The Death of Neoliberal Realism?
Wheeler, Zachariah (2020-06)
Solution Blow Spinning of Polyvinylidene Fluoride Based Fibers for Energy Harvesting Applications: A Review
Atif, Rasheed; Khaliq, Jibran; Combrinck, Madeleine; Hassanin, Ahmed H.; Shehata, Nader; Elnabawy, Eman; Shyha, Islam (MDPI, 2020-06-07)
Polyvinylidene fluoride (PVDF)-based piezoelectric materials (PEMs) have found extensive applications in energy harvesting which are being extended consistently to diverse fields requiring strenuous service conditions. Hence, there is a pressing need to mass produce PVDF-based PEMs with the highest possible energy harvesting ability under a given set of conditions. To achieve high yield and efficiency, solution blow spinning (SBS) technique is attracting a lot of interest due to its operational simplicity and high throughput. SBS is arguably still in its infancy when the objective is to mass produce high efficiency PVDF-based PEMs. Therefore, a deeper understanding of the critical parameters regarding design and processing of SBS is essential. The key objective of this review is to critically analyze the key aspects of SBS to produce high efficiency PVDF-based PEMs. As piezoelectric properties of neat PVDF are not intrinsically much significant, various additives are commonly incorporated to enhance its piezoelectricity. Therefore, PVDF-based copolymers and nanocomposites are also included in this review. We discuss both theoretical and experimental results regarding SBS process parameters such as solvents, dissolution methods, feed rate, viscosity, air pressure and velocity, and nozzle design. Morphological features and mechanical properties of PVDF-based nanofibers were also discussed and important applications have been presented. For completeness, key findings from electrospinning were also included. At the end, some insights are given to better direct the efforts in the field of PVDF-based PEMs using SBS technique.
Numerical Study of Shear Banding in Flows of Fluids Governed by the Rolie-Poly Two-Fluid Model via Stabilized Finite Volume Methods
Abuga, Jade Gesare; Chinyoka, Tiri (MDPI, 2020-07-09)
The flow of viscoelastic fluids may, under certain conditions, exhibit shear-banding characteristics that result from their susceptibility to unusual flow instabilities. In this work, we explore both the existing shear banding mechanisms in the literature, namely; constitutive instabilities and flow-induced inhomogeneities. Shear banding due to constitutive instabilities is modelled via either the Johnson–Segalman or the Giesekus constitutive models. Shear banding due to flow-induced inhomogeneities is modelled via the Rolie–Poly constitutive model. The Rolie–Poly constitutive equation is especially chosen because it expresses, precisely, the shear rheometry of polymer solutions for a large number of strain rates. For the Rolie–Poly approach, we use the two-fluid model wherein the stress dynamics are coupled with concentration equations. We follow a computational analysis approach via an efficient and versatile numerical algorithm. The numerical algorithm is based on the Finite Volume Method (FVM) and it is implemented in the open-source software package, OpenFOAM. The efficiency of our numerical algorithms is enhanced via two possible stabilization techniques, namely; the Log-Conformation Reformulation (LCR) and the Discrete Elastic Viscous Stress Splitting (DEVSS) methodologies. We demonstrate that our stabilized numerical algorithms accurately simulate these complex (shear banded) flows of complex (viscoelastic) fluids. Verification of the shear-banding results via both the Giesekus and Johnson-Segalman models show good agreement with existing literature using the DEVSS technique. A comparison of the Rolie–Poly two-fluid model results with existing literature for the concentration and velocity profiles is also in good agreement.
Perovskite Solar Cell with Added Gold/Silver Nanoparticles: Enhanced Optical and Electrical Characteristics
Hajjiah, Ali; Badran, Hussein; Kandas, Ishac; Shehata, Nader (MDPI, 2020-07-28)
Different perovskite materials, such as methylammonium lead triiodide MAPbI₃, exhibit many outstanding and desirable properties in solar energy harvesting. In this paper, the enhancement of perovskite solar cells’ both optical and electrical characteristics through adding either gold (Au) or silver (Ag) nanoparticles (NPs) using different simulations was studied. The used plasmonic nanoparticles were found to be able to compensate for the low absorption of MAPbI₃ in the visible with optical coupling resonance frequencies close to that spectrum. Optimal diameters of Au and Ag NPs were found and simulated, and their impact on different parameters such as transmission, absorption, reflection, external quantum efficiency (EQE), open circuit voltage, short-circuit current density, fill factor, and most importantly, efficiency of the perovskite solar cell, have been investigated.

Browse

Browsing Graduate Student Papers by Issue Date

Results Per Page

Sort Options