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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
121

Evaluation of suitable chilled, extended semen preservation time and their effects of different artificial insemination techniques on the fertility of indigenous Venda goats

Monyeleote, Vukosi 18 September 2017 (has links)
MSCAGR (Animal Science) / Department of Animal Science / The aims of the study were to evaluate the effects of dilution and chilled storage time on the quality of semen, and of different artificial insemination techniques on fertility in artificially inseminated indigenous Venda does. Fresh semen was collected using an artificial vagina from three Boer bucks aged 4±1.55 years once every four days during July and August 2016. Semen was pooled and samples were divided into two equal parts, which were extended using Biladyl® extender at ratios of 1:5 and 1:10 v/v (semen to extender), before refrigeration for 120 hours at 5 °C. The fresh undiluted semen and freshly extended semen were evaluated in six replicates for sperm motility, live-dead and sperm morphology using the Sperm Class Analyzer (SCA). Extended semen continued to be evaluated at 24 hour intervals for 120 hours. Ninety indigenous Venda does were obtained from different flocks in the Vhembe district and kept intensively in one 10 m x 40 m pen at the University of Venda experimental farm in the goat feedlot. The does were fed and watered ad libitum. After acclimatization for 14 days, estrus was synchronized using a controlled internal drug release (CIDR) containing 0.3 g of progesterone. Upon removal of the CIDR, does were injected 10 mg of PGF2α (Lutalyse® dinoprost tromethamine) Sterile Solution. At 24 hours after the removal of the CIDR, the does were injected intramuscularly with 300 international units (IU) of equine chorionic gonadotrophin (eCG). Forty eight hours after the removal of the progesterone, freshly collected and diluted (1:5 ratio ~150x106 sperm/ml), five day-stored semen were used to inseminate the does using cervical (CAI), trans-cervical (TAI), and laparoscopic artificial (LAI) insemination methods in a complete randomized design (CRD) with a 2 X 3 factorial arrangement of the treatments with 15 replications per treatment. The does were tested for pregnancy after 30 days using ultrasonography. Analyses of variance was performed on the pregnancy, kidding rates and on prolificacy using the GLM procedure of Minitab (Minitab 2013). Significant differences in all motility parameters were observed between the extension ratios and storage time (P<0.01). There were significant interactions between the extension ratio and storage time (P<0.05) on the sub-population of sperm cells with non-progressive motility (NON-P). Significant (P<0.01) interaction was observed between the semen extension ratio and storage time on medium and slow spermatozoa (P<0.01). The method of insemination did not (P>0.05) affect fertility, though both pregnancy and kidding rates numerically decreased in the order laparoscopic insemination (LAI)≥ trans-cervical insemination (TAI)≥ cervical insemination (CAI). Overall, 71% kidding rate was achieved.
122

University Budget Models, Institutional Size, and Student Outcomes

Batchelder, James P 01 December 2020 (has links)
The purpose of the non-experimental quantitative research study was to identify if there is a significant difference between the types of budget model an institution utilizes, institutional size, and student enrollment, retention, and graduation rates. This study was to identify if there is significant difference between institutional size and the type budget model utilized. Member institutions of the American Association of State Colleges and Universities (AASCU) were selected to participate in this study due to their similarities of mission and admissions policy. AASCU institutions share a common mission that focuses on access, innovation, regional support, and inclusion. AASCU institutions are all public regional institutions. Larger institutions within the study presented significantly higher retention and graduation rates compared to medium size institutions. I used the Carnegie classification of size as institutions that have enrollments less than 3,000 as small, institutions that have enrollments less than 10,000 as medium, and institutions with enrollments greater than 10,000 as large. I study found no significant difference in the types of budget model utilized and the student outcomes related to enrollment, retention, or graduation rates. I did indicate that institutions that utilized a more decentralized budgeting approach had higher enrollment percentages and higher retention and graduation rates than institutions that utilized a centralized budget model. I also did not identify any significant difference in the size of an institution and the type of budget model utilized.
123

Development of Intermediate and High Strain Rate Experimentation and Material Modeling of Viscoplastic Metals

Whittington, Wilburn Ray 11 December 2015 (has links)
This work presents a combined theoretical-experimental study of strain rate behavior in metals. The method is to experimentally calibrate and validate an Internal State Variable (ISV) constitutive model with a wide range of strain rate sensitivity. Therefore a practical apparatus and methodology for performing highly sought-after intermediate strain rate experimentation was created. For the first time in reported literature, the structure-property relations of Rolled Homogeneous Armor is quantified at the microscale and modeled with varying strain rates, temperatures, and stress states to capture plasticity and damage with a single set of constants that includes intermediate strain rates. A rolled homogeneous armor (RHA) was used as a material system to prove the methodology. In doing so, a newly implemented strain rate dependent nucleation parameter for RHA was implemented to transition the dominant damage mechanism from void growth to void nucleation as strain rate increased. The ISVs were utilized in finite element analysis for robust predictability of mechanical performance as well as predictability of microstructural evolution with regards to void size and number distribution. For intermediate strain rate experiments, robust load acquisition was achieved using a novel serpentine transmittal bar that allowed for long stress waves to traverse a short bar system; this system eliminated load- ringing that plagues servo-hydraulic systems. A direct hydraulic loading apparatus was developed to provide uniform strain rates throughout intermediate rate tests to improve on the current limitations of the state-of-the-art. Key recommendations on the advancement of predictive modeling of dynamic materials, as well as performing advanced dynamic experimentation, are elucidated.
124

System Performance of an Over-Water Propagation for an LMDS Link

Tan, Chin Khee 10 May 2001 (has links)
The growth of broadband Internet access has paved the way for the development of many newer existing technologies. As the costs of implementing broadband access soar, the best alternative will be to use wireless technologies. At a carrier frequency of about 28 GHz, the potential benefits of Local Multipoint Distribution Service (LMDS) will eventually outweigh those of its current competitors in the wired market. Since the rural communities will reap the most benefits from this technology due to its low costs, studies on the channel behavior and terrain relationships must be done. This thesis aims to provide a preliminary study on the effects of propagating an LMDS signal over a lake surface. Currently, there is not enough information to prove the feasibility of deploying an LMDS system for this terrain. Some background on the technology and rough surface theory is provided for the reader to better understand the environment that is being investigated. Simulation results are presented as a guide to assist future researchers to conduct a field measurement campaign. A block diagram of a potential measurement system is also provided to aid in the development of the tools necessary for the measurement of an actual channel. / Master of Science
125

Portable Heart Rate Monitor Feasibility Study

Tzannidakis, Evangelos 01 1900 (has links)
One of two project reports. The other is designated PART A: McMASTER (ON-CAMPUS) PROJECT / <p> It is well known that heart rate is an important physiological parameter. In some cases, continuous monitoring of active subjects is desireable. </p> <p> The report focuses on the feasibility of a miniaturized, portable heart rate monitor. Good artifact rejections, low power consumption small size and ease of use are of primary importance in such design. In order to keep size as low as possible a single cell (1 .5 V) supply voltage is used. </p> <p> A LED - phototransistor type of transducer was chosen for its good artifact rejection and simplicity of application. The transducer clips on the subject's earlobe. Light transmitted through the earlobe is amplitude modulated by the heart (blood) pulses and detected by the phototransistor thus providing electrical signal. </p> <p> In order to keep current drain low, the LED was powered by ~ 1% duty cycle pulses. The rest of the system was designed to comply with the requirements of the transducer. The detected train of pulses were preamplified and the original modulating waveform (heart pulse) reconstructed by a "sample and hold" circuit. The reconstructed signal was amplified by a narrow-band-pass amplifier filter. </p> <p> An astable and two monostable multivibrators perform the necessary timing. Two integrated circuits were also employed: a voltage regulator, to provide stable reference voltages where needed and the output amplifier filter, providing the bulk of the gain. </p> <p> A working prototype was built and suggests that a personalized heart rate monitor is quite feasible. The whole circuit can be integrated, with the exception of few capacitors and perhaps some trimming potentiometers. </p> / Thesis / Master of Engineering (MEngr)
126

Catalysis of Gas Hydrates by Biosurfactants in Seawater-Saturated Sand/Clay

Kothapalli, Chandrasekhar R 03 August 2002 (has links)
An estimated 1000 trillion cubic meters of gas in the unconventional hydrocarbon resource of gas hydrates in the world?s ocean floors far exceeds the known hydrocarbons in conventional reserves like coal, petroleum, and natural gas. These hydrate deposits also contain massive amounts of the greenhouse gases like methane and carbon dioxide. As relatively little is known about the oceanloor natural gas hydrates, mechanisms leading to the formation of these hydrates in ocean sediments need to be investigated before the significant technical challenges of recovery and environmental hazards are addressed. The subject research focuses on possible catalytic effects of biosurfactants on the formation of natural gas hydrates in oceanloor sediments. Sand/clay packs were saturated with seawater containing 1000 ppm of biosurfactant and pressurized with natural gas of 90 mole% methane, 6 mole% ethane and 4 mole% propane. The experimental results showed that gas hydrates formation in porous media is catalyzed by biosurfactants at very low concentrations. Commercially available representatives from the five biosurfactant classifications that microbes produce were purchased and evaluated in sand/clay packs at hydrateorming conditions. The rate of formation and induction time differed in the presence of bentonite and kaolin. The surface activities of biosurfactants were either specific to sand or clay surfaces. While in the presence of bentonite, Surfactin decreased hydrate induction time by 71% over a reference test with no biosurfactant in the seawater; Surfactin lowered induction time by 25% in the presence of kaolin. Rhamnolipid reduced the induction time by 58% in the presence of bentonite and by 66% in the presence of kaolin. Snomax and Emulsan, belonging to the classification of polysaccharide lipid complexes, reduced induction time by 30 to 40% in the presence of both kaolin and bentonite. Fatty acids reduced the induction time by 55% in the presence of bentonite and by 20% in the presence of kaolin. Surfactin enhanced the rate of formation by 400% in the presence of bentonite, but it had minimal effect in the presence of kaolin. Emulsan and Snomax increased the rate of formation by 250%, while rhamnolipid and phospholipids doubled formation rate in the presence of bentonite. Emulsan increased the rate of formation by 800%. In seawater, at hydrateorming conditions, rhamnolipid was found to have a critical micellar concentration of 12 ppm. This very low value of CMC suggests that minimal bacterial activity in ocean sediments could greatly catalyze hydrate formation. The recent analysis by Lanoil et al. (2001) of sediments from around gas hydrate mounds in the Gulf of Mexico gives a direct association between microbes and gas hydrates and supports the conclusions of the subject work.
127

MULTIFRACTAL MODELS AND SIMULATIONS OF THE U.S. TERM STRUCTURE

Jamdee, Sutthisit 03 May 2005 (has links)
No description available.
128

An Instantaneous Frequency Based Approach to Estimate Heart Rate and Calculate Heart Rate Variability Metrics

Jayasooriya, Don Cyril Prathap Vishwanath 05 June 2024 (has links)
An emerging diagnostic tool for detecting heart and physiological conditions is heart rate variability (HRV). Copious research continuously discovers relationships between heart rate variability metrics and physiological functions and cardiac health. The first step in calculating HRV metrics is calculating heart rate. Heart rate is typically calculated using the interval between R peaks in an EKG signal. Consequently, heart rate measurements rely on the presence of distinctive R peaks and the accurate detection of them. The study is motivated by the drawbacks associated with using R peaks to calculate instantaneous heart rate. In this study we present an alternative method (that does not rely on R peaks) based on the concept of instantaneous frequency to estimate heart rate from electrocardiogram (EKG) signals. The EKG signal is filtered to extract constituent frequency components that correlate with the instantaneous heart rate. The filtered signal is then fed into an algorithm that outputs a signal that shows the variation of the instantaneous heart rate with time. This output signal contains noise due to the behavior of the algorithm at zero crossings of the filtered EKG signal. Two methods for filtering the output signal are also presented in the study. The proposed method was able to successfully estimate the instantaneous heart rate and allowed the subsequent calculation of frequency domain HRV metrics. This method potentially provides more information for HRV analysis and addresses the drawbacks associated with methods based on R peak detection. / Master of Science / Heart disease is the leading cause of death in America accounting for about 20% of all deaths. Consequently, both the public and the medical community are engrossed in cardiovascular health, research that enables early detection of heart disease and novel treatments for cardiac conditions. An emerging diagnostic tool for detecting heart and physiological conditions is heart rate variability (HRV). Copious research continuously discovers relationships between heart rate variability metrics and physiological functions and cardiac health. The first step in calculating HRV metrics is calculating heart rate. With the rise in popularity and improvement of wearable technologies, it has become easier than ever to collect data and perform diagnostics, often in real time. As such the need for robust methods and algorithms to perform these calculations are ever more important. The study is motivated by drawbacks associated with the conventional method used to calculate heart rate from electrocardiogram signals. In this study we present a more robust method to calculate heart rate from EKG signals allowing more accurate HRV metrics to be calculated. In this study we present an alternative method based on the concept of instantaneous frequency to estimate heart rate from electrocardiogram (EKG) signals. We identify the shortcomings of the conventional method of estimating heart rate and discuss the strengths and weaknesses of the alternative method introduced. We then calculate and compare the HRV metrics calculated from the proposed method and the conventional method. The method presented also has the potential to be used on other signals that measure the heart's activity such as Photoplethysmography signals (PPG) allowing it to be used on wearable devices. We hope that the information provided, and the findings presented in this study will be utilized by the medical community and researchers for future research related to heart rate variability.
129

A Mixed Methods Study of the Air Force Jrotc Leadership Program at an Urban High School in Southeastern Virginia

Ameen, Shafeeq Aqeel 09 December 2009 (has links)
The JROTC program is one of service and commitment. Its mission is to build better citizens and give them a sense of pride in service to their fellow man. Today these core principles are still needed, but with the increase in the student dropout rate, the JROTC program can be one of many alternatives needed to help public education reach today's youth who are struggling to stay in school. The purpose of this mixed methods study was to examine the impact of the Air Force JROTC Leadership Program on the grade point average (GPA), attendance rate, disciplinary referrals, and dropout rate of JROTC students at an urban high school in southeastern Virginia. The study also addressed the perceptions of school administrators, Air Force JROTC instructors, teachers, JROTC students and their parents on students enrolled in the program during the 2005-2009 school years. Descriptive statistics were used to determine the means, standard deviations and frequency distributions for the groups in the study. Three independent sample t-tests and seven one-way Analysis of Variance (ANOVA's) were used to determine where there was a statistically significant difference for each group. The Tukey post hoc procedure was used to determine where the difference occurred in the variables. There were three major findings revealed in this study. The first finding indicated that students who participated in the JROTC program had lower grade point averages (M =2.47, SD = 1.17) than non-JROTC participants (M = 3.00, SD = 0.94). Second, administrators had higher levels of agreement (100%) than AFJROTC instructors, teachers, JROTC students and parents that leadership skills were developed in the AFJROTC program. Third, JROTC students (12%) and parents (7%) had lower levels of agreement than administrators, AFJROTC instructors and teachers that the AFJROTC program is used as a recruitment tool. Focus groups results showed strong support for the program from administrators, teachers, JROTC students and parents. These findings suggest that if school districts and educational leaders are to benefit from implementing the AFJROTC program they must understand that the program is not designed to impact academics. The program is designed to develop leadership skills along with helping students become better citizens. Educational leaders in school districts should read the findings and consider utilizing the program as a possible alternative to help students to develop skills to keep them from dropping out of school. / Ph. D.
130

Effects of Exchange Rate Misalignment on Agricultural Producer Support Estimates: Empirical Evidence from India and China

Cheng, Fuzhi 31 October 2005 (has links)
There have been different degrees of exchange rate disequilibrium in the developing countries during recent transition or reform periods. The level of the exchange rate and its misalignment can have significant impacts on agricultural policy measures such as the Producer Support Estimates (PSEs). However, little efforts have been made to explicitly take into account the issue of exchange rate misalignment. In the conventional PSE studies the prevailing actual (nominal) exchange rates are usually used. There is general agreement that the use of actual exchange rates may introduce a bias in the PSE calculations, and that this bias can be substantial when the actual rates are significantly out of equilibrium, but there is much less agreement on the most appropriate alternative. This dissertation proposes a theoretical and an empirical model for estimating equilibrium exchange rates. Within the context of these models, the equilibrium exchange rates are argued to be determined by a group of real economic fundamentals. These fundamentals within this study include technological progress (Balassa-Samuelson effect), levels of government expenditure, world interest rate, net capital inflows, terms of trade, and openness of the economy. Base on various time series techniques and using data from India and China, sensible long-run relationships are identified between the real exchange rate and these economic fundamentals. The long-run co-integrating relationships are used to derive the equilibrium exchange rates and to gauge corresponding misalignments for the currencies in the two countries. The relevance and usefulness of the exchange rate equilibrium and disequilibrium in the calculation of the PSEs for India and China are then discussed. Results from the commodity-specific measures including the Market Price Support (MPS) and the PSE show that agricultural support levels are quite sensitive to alternative exchange rate assumptions. Specifically, exchange rate misalignments have either amplified or counteracted the direct effect on agriculture from sectoral-specific policies. With a few commodity exceptions such an indirect effect in both countries is relatively small in magnitude and dominated by the direct effect. This is also the case when the indirect effect rises substantially as a result of more misaligned exchange rates. Counterfactual MPS measure calculated assuming the exchange rate is in equilibrium with different exchange rate pass-through is also presented. It is shown that when no exchange rate pass-through to domestic prices occurs, the transfer of the indirect effect of exchange rate misalignment into the counterfactual MPS is full. But when there is exchange rate pass-through, even though partially, the transfer of indirect effect is significantly smaller. Results based on the commodity-specific PSE show that the exchange rate effect also depends on the relative importance of different PSE components. In addition to a positive impact on the direct effects measured by commodity-specific PSE compared to those measured by commodity-specific MPS, the increasing share of budgetary expenditures in India's agricultural support in recent years has resulted in more pronounced indirect effects. For China, the exchange rate effects are more similar between the PSE and the MPS measures at the commodity level because of the dominance of the MPS component relative to the budgetary payments in the PSEs. Moving from commodity-specific to aggregate measures, one can observe a similar pattern of agricultural support. However, the exchange rate effect measured by the total PSE appears to be more important: it becomes several times larger in magnitude than the direct effect in periods of severe exchange rate misalignment. The exchange rate effect when the PSE is "scaled up" from covered commodities to an estimate for the total agricultural sector is also demonstrated even though the assumption imposed by scaling-up may be unrealistic if price support is concentrated among those products included in the analysis. Since the commodity coverage in both countries tends to be incomplete and the scaling-up procedure leads to a total MPS component of greater magnitude, larger exchange rate effects are found in the scaled-up than the non-scaled-up version of the total PSEs. The impact of scaling-up on the indirect effect is proportional to the share of covered commodities in the total value of agricultural production. Again for the PSEs at both the commodity and aggregate levels, the counter factual measures indicate a full transfer of indirect effect of exchange rate when no exchange rate pass-through is assumed. A large portion of the indirect effect disappears when incomplete exchange rate pass-through is assumed resulting in a smaller transfer of the effect to the counter factual PSEs. / Ph. D.

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