Browsing by Author "Holtzman, Golde I."

Now showing 1 - 14 of 14
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    Assessing the Contamination Risk of Private Well Water Supplies in Virginia
    Bourne, Amanda C. (Virginia Tech, 2001-07-18)
    When well water becomes contaminated to the extent that is does not meet EPA drinking water quality standards, it is considered unsafe for consumption. Nitrate and total coliform bacteria are both health contaminants and are both regulated in public water systems. A nitrate concentration of 10 mg/L or higher is considered unsafe, as is the presence of total coliform bacteria. Well degradation, inadequate well construction, and aquifer contamination can all result in contamination of well water. Factors such as well type, well age, well depth, treatment devices, population density, household plumbing pipe materials, and nearby pollution sources may affect household water quality. The specific objective of this study was to determine which factors influence nitrate levels and total coliform presence/absence of household well water. If possible, these influencing factors would be used to develop a relationship that would allow household residents to predict the nitrate level and total coliform presence/absence of their well water. As a result, a means of predicting the contamination risk to a specific well water supply under a given set of conditions, in addition to increasing awareness, could provide the homeowner with a rationale for further investigating the possibility of contamination. Existing data from the Virginia Cooperative Extension Household Water Quality Testing and Information Program were assembled for analyses in this project. The data consisted of 9,697 private household water supplies sampled from 1989-1999 in 65 Virginia counties. Initially, the entire state of Virginia was analyzed, followed by the five physiographic provinces of Virginia: the Blue Ridge, Coastal Plain, Cumberland Plateau, Ridge & Valley, and Piedmont. Ultimately, Louisa County was investigated to evaluate the possibility that better models could be developed using smaller land areas and, consequently, less geological variation. Least squares regression, both parametrically and non-parametrically, was used to determine the influence of various factors on nitrate levels. Similarly, logistic regression was used to determine the influence of the same parameters on nitrate categories, presence/absence of total coliform, and risk categories. Using stepwise model-building techniques, based primarily on statistical significance (p-values) and partial coefficient of determination (partial-R2), first and second-order linear models were evaluated. The best-fitting model only explained 58.5% of the variation in nitrate and none of the models fit well enough to be used for prediction purposes. However, the models did identify which factors were, in a statistical sense, significantly related to nitrate levels and total coliform presence/absence and quantified the strength of these relationships in terms of the percent of variation explained.
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    The effect of isoflavone supplementation on cardiovascular disease parameters in men undergoing 80% VO₂pk exercise
    Hart, Vanessa Lynn Rogowsky (Virginia Tech, 2002-05-28)
    Atherosclerosis, one of the major causative factors of cardiovascular diseases (CVD), is thought to be initiated by oxidative stress. Particular attention has been paid to the atherogenic effects of oxidative damage on low density lipoproteins (LDL). Current research shows that dietary antioxidant supplementation protects against oxidative stress, and therefore may present preventative measures and treatments for patients with diseases influenced by oxidative stress. Isoflavones found in soy, such as genistein and daidzein are reported to have potent antioxidant properties and have been shown to inhibit LDL oxidation in vitro. Although there is a strong base of data that supports the correlation between soy consumption, cholesterol reduction and cardiovascular protection, it remains to be elucidated whether it is the soy protein, the isoflavone, or a combination of both that confers benefits. This study investigated the effect of isoflavone supplementation on the following parameters: plasma genestein levels, oxidized LDL levels, plasma cholesterol, vitamin E, and C-reactive protein. Elevated serum cholesterol and C-reactive protein (CRP) have been identified as risk factors for cardiovascular disease. In a randomized, double-blind, placebo-controlled study, 150 mg/d isoflavone was supplemented for four weeks by 30 healthy, yet sedentary male subjects who underwent 30 minute exercise sessions at 80% VO2pk before and after a 28 day period of supplementation. The purpose of the exercise was to induce oxidative stress. The average plasma genistein and daidzein concentrations increased significantly after isoflavone supplementation from 0 ng/ml to 561.6 ± 39.3 and 466.3 ± 35.5 ng/ ml (SE) respectively (P < 0.0001), compared to 0 ng/ml in the placebo group throughout the study. There was no significant beneficial effect of isoflavone supplementation on oxidized LDL, plasma vitamin E concentrations, total cholesterol, LDL, HDL, or triglycerides. Isoflavone supplementation resulted in an average increase in CRP levels by 44% (P = 0.014), which was opposite from expectations. This study supports the theory that it may not be soy isoflavones alone that benefit lipid profiles, or offer protection from oxidative stress.
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    The Effects of Resistant Starch Intake in African-American Americans at Increased Risk for Type 2 Diabetes
    Penn-Marshall, Michelle (Virginia Tech, 2006-05-05)
    Background: African-Americans are a vulnerable population group with disproportionately elevated rates of type 2 Diabetes Mellitus (DM). Resistant starch is a promising food ingredient that has the potential to reduce the risk factors involved in the development of type 2 DM. To date, there is a dearth of published research studies on the effect of resistant starch on African-Americans who are at increased risk for type 2 DM. Objective: The major objective of this study was to determine if daily consumption of approximately twelve grams of high-maize™ 260 resistant starch (RS) added to bread improved glucose homeostasis by monitoring changes in fasting plasma glucose, fructosamine, hemoglobin A1c, insulin, glucagon-like peptide-1, C-reactive protein, homeostasis model assessment insulin resistant (HOMA- IR) and beta-cell function (HOMA-Beta), serum acetate, propionate, and butyrate levels. Design: A fourteen-week, randomized, double-blind, within-subject crossover design feeding study was carried out in African-American males (n=8) and females (n=7) at increased risk for type 2 DM who resided in Southwest Virginia. All participants consumed bread containing added RS or control bread (no added RS) for six-weeks. RS and control bread feedings were separated by a two-week washout period. Results: Fasting Plasma Glucose (FPG) levels were significantly lower (P = 0.0179) after six-week control bread feedings compared to baseline. FPG levels were also significantly lower (P < 0.0001) after two-week washout period than at baseline. FPG levels were significantly higher (P < 0.0001) after six-week resistant starch bread feeding than at washout. FPG levels due to consumption of resistant starch versus control bread approached significance (P = 0.0574). Fructosamine levels were significantly lower (P = 0.0054) after control bread and resistant starch bread (P < 0.0012) consumption compared to baseline. No significant differences were found in fructosamine levels due to resistant bread intake versus control (P = 0.9692). Mean baseline HbA1c levels were 6.9% (n=15). This value was slightly lowered to 6.79% (n=14) at the end of the fourteen-week study, although statistical significance was not found. Mean ± standard errors for HbA1c values were 6.9% ± 0.18% and 6.9% ± 0.14% at baseline for the sequence groups, resistant starch first (n=7) and control treatment first (n=8) groups, respectively. Mean± standard error HbA1c values were 6.7%± 0.27% and 6.9% ± 0.27% at the conclusion of fourteen-week study for sequence groups, resistant starch first group (n=7) and control treatment first group, respectively. Baseline mean and standard errors C-reactive Protein (CRP) levels for male and female combined results were 0.62 ± 0.16 mg/dL (n=15). Mean CRP levels were 0.53 ± 0.12 mg/dL for resistant starch bread and 0.64 ± 0.21 mg/dL for control bread feeding periods. No significant differences were found for treatment, gender, or sequence effects for C-reactive protein levels during the fourteen-week study (P > 0.05). Mean HOMA-IR levels following six-week resistant starch and control bread consumption decreased to normal values (> 2.5), although no significant differences were found for treatment (P = 0.5923). Conclusions: Eighty-seven grams of Hi- maize™ 260 Resistant Starch added to baked loaves of bread consumed by a free-living African-American population at increased risk for type 2 diabetes did not consistently show significance in all clinical indicators and biochemical markers assessed. On the basis of the evidence in this study we do not have evidence that this amount of resistant starch in this population's diet will prevent the onset of diabetes. However, results are suggestive that higher levels of resistant starch in a more controlled experiment could reduce clinical risk factors for type 2 diabetes.
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    An Investigation of the Relationships among Consumer Characteristics, Attitude, and Purchase Intention in Apparel Mass-customization
    Yang, Jung-Ha (Virginia Tech, 2011-06-30)
    Mass-customization is a form of consumer-centric business practice, which is a hybrid of customization and mass-production (Gilmore & Pine II, 1997). It is the use of flexible processes and organizational structures to produce individually customized apparel products at the low cost of a standardized mass-production system (Hart, 1995). Very limited academic consumer research has been conducted in the area of apparel mass-customization. The purposes of the study were (a) to investigate consumers' purchase intentions of mass-customized apparel, (b) to examine the relationships among consumer characteristics, perceived usefulness, perceived behavioral control, attitude toward using apparel mass-customization, and purchase intention of mass-customized apparel, and (c) to identify the predictors of the overall purchase intentions and those of the purchase intentions of specific types of mass-customized apparel (i.e., design, fit and personalization mass-customized apparel). A conceptual model was developed, and eight hypotheses were generated to test the proposed relationships among the variables. A questionnaire was developed as the instrument of collecting data. A national sample of 474 male adults was recruited by a market research company. Statistics such as descriptive statistics, factor analysis, and stepwise multiple regression analysis were used to analyze the collected data. The results indicated that more than half of the respondents were willing to purchase mass-customized dress shirts. The relationships among consumer characteristics, perceived usefulness, perceived behavioral control, attitude toward using apparel mass-customization, and purchase intention of mass-customized apparel were confirmed, and the predictors of the overall purchase intention and of the purchase intention of specific types of mass-customized apparel were identified. Based on the results, in-depth discussions and related marketing implications were provided.
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    Long-Term Water Quality Trends in Virginia's Waterways
    Zipper, Carl E.; Holtzman, Golde I.; Darken, Patrick F.; Thomas, Pamela J.; Gildea, Jason J.; Younos, Tamim M. (Virginia Water Resources Research Center, 1998-12)
    The quality of water in Virginia’s rivers and streams affects the health and welfare of Virginia’s citizens, quality of life in the Commonwealth’s communities, and the state’s economic development potential. Each year, large sums are spent by both the state and the private sector to protect, improve, and monitor the quality of Virginia’s waters. Yet, little information is available on the long-term success of these water-quality-protection expenditures. The research described in this report was the first-phase of a two-phased, multi-year effort to enhance the Virginia Department of Environmental Quality’s (DEQ) capability to detect and interpret long-term water-quality trends in Virginia’s watersheds (Figure 1). This report summarizes results of long-term trend analyses of Virginia’s water-quality monitoring data collected over varying periods at individual monitoring stations. Data typically extend from the late 1960s or early-mid 1970s through early 1997. The second phase of this multi-year effort, scheduled to conclude in October 1999, will provide DEQ with the capability to conduct similar trend analyses in-house. The study will also determine relationships between observed water-quality trends and watershed characteristics (Zipper et al., 1997).
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    Multiple stresses by insect and plant-competition on growth and productivity of Canada thistle
    Ang, Ban-Na (Virginia Tech, 1992-08-04)
    Canada thistle is an aggressive perennial weed throughout temperate areas for both the northern and southern hemisphere. As various single tactics have shown limited success in controlling this weed, I believe that a combination of different stress factors is necessary for effective sustainable control of Canada thistle. This study evaluates the competitive abilities of tall fescue grass and crownvetch in conjunction with a thistle feeding insect for Canada thistle control. The goal of the study was to determine what levels of the herbivore and plant competition are needed to suppress Canada thistle. Field studies were conducted to determine the effects of multiple stresses caused by defoliation and plant competition on growth and survival of Canada thistle (Cirsium arvense Scop.). Plant competition was from a cornbination of tall fescue (Festuca arundinaceae Schreb.) and crownvetch (Coronilla varia L). Artificial defoliation was used to determine the influence of level and frequency of defoliation in combination with plant competition on Canada thistle. The effects of various densities of a defoliator, Cassida rubiginosa (Coleop:Chrysonlelidae), in the presence and absence of plant competition were also determined. A three-season study determined the combined effects of C. rubiginosa and plant competitors at various densities on the growth and productivity of Canada thistle plantings of various ages.
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    One-sided screening procedure using multiple normally distributed variables
    Boskov, Lazar (Virginia Tech, 1994-08-19)
    In the situations in which the proportion of acceptable products from the output of a production process is below the required level, it is essential to screen out the products of unacceptable quality. By eliminating the products of low quality, the proportion of products of the acceptable quality in the remaining population of products is raised. In some instances it is not possible to make quality assessment by measuring directly on the variable of interest (performance variable). The measure is not possible because it destroys or degrades the product. In such cases, auxiliary variables which are correlated with the performance variable can be used to indirectly determine the quality of the product. These variables are called screening variables. Under the assumption that the performance and the screening variables follow a multivariate normal distribution, a regression model is used to predict the value of the performance variable. Using Monte Carlo simulation, the performance of the regression model is evaluated. The evaluation is done for two cases: (1) the parameters of the underlying distribution are known, (2) the parameters are not known. The results show that the efficiency of the screening depends highly on the value of the correlation coefficient between the performance variable and a linear combination of the screening variables. Furthermore, the comparison with the previously developed models is performed. Findings show that the regression model is very useful, especially in the cases in which multiple screening variables are available and the parameters of the underlying distribution are not known.
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    Relationships Between Land Use, Land-Use Change, and Water-Quality Trends in Virginia
    Gildea, Jason James (Virginia Tech, 2000-05-10)
    This research examines the relationships between land use and surface water quality trends in Virginia. Data from 168 surface water quality monitoring stations throughout Virginia were analyzed for trends for the period of 1978 to 1995. Water-quality data available at these stations included dissolved oxygen saturation (DO), biochemical oxygen demand (BOD), pH, total residue (TR), non-filterable residue (NFR), nitrate-nitrite nitrogen (NN), total Kjeldahl nitrogen (TKN), total phosphorus (TP), and fecal coliform (FC). A seasonal Kendall analysis was used to determine trends for each water-quality parameter at each station; this analysis produced an indicator (Kendall's tau) of improving or declining water quality. Median values for each water-quality variable were also determined at the monitoring stations. Virginia land use was determined from the USGS Land Use Land Cover (LULC) data (1970s) and the Multi-resolution Land Characteristics (MRLC) data (1990s). Land-use variables included urban, forest, pasture, cropland, total agriculture, and urban change. These six variables were correlated with Kendall's tau to determine if relationships exist between water-quality trends and land use. Water-quality medians and land use were also correlated. In general, highly forested watersheds in Virginia were associated with improving water quality over the 1978 to 1995 study period. These watersheds were also commonly associated with better water quality as measured by the water-quality medians. Watersheds with less agricultural land tended to be associated with improving water quality. Better water quality, as measured by the water-quality medians, was generally associated with watersheds possessing fewer urban acres. There were few significant relationships between water-quality medians and agricultural variables.
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    A response surface approach to data analysis in robust parameter design
    Kim, Yoon G. (Virginia Tech, 1992-09-15)
    It has become obvious that combined arrays and a response surface approach can be effective tools in our quest to reduce (process) variability. An important aspect of the improvement of quality is to suppress the magnitude of the influence coming from subtle changes of noise factors. To model and control process variability induced by noise factors we take a response surface approach. The derivative of the standard response function with respect to noise factors, i. e., the slopes of the response function in the direction of the noise factors, play an important role in the study of the minimum process variance. For better understanding of the process variability, we study various properties of both biased and the unbiased estimators of the process variance. Response surface modeling techniques and the ideas involved with variance modeling and estimation through the function of the aforementioned derivatives is a valuable concept in this study. In what follows, we describe the use of the response surface methodology for situations in which noise factors are used. The approach is to combine Taguchi's notion of heterogeneous variability with standard design and modeling techniques available in response surface methodology.
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    A "Screening Approach" for Nutrient Criteria in Virginia: Report of the Academic Advisory Committee for Virginia Department of Environmental Quality
    Zipper, Carl E.; Holtzman, Golde I.; Shabman, Leonard A.; Stephenson, Stephen Kurt; Walker, Jane L.; Yagow, Eugene R. (Virginia Water Resources Research Center, 2012-07)
    Under the Clean Water Act (CWA), criteria are components of water quality standards that are intended to protect designated uses for waters of the U.S. Nitrogen (N) and phosphorous (P) (“nutrients”) are common water contaminants that challenge conventional methods for establishing water quality criteria for an essential designated use, the protection of aquatic life. Unlike many water contaminants for which criteria have been established, nutrients typically do not exert primary effects on aquatic life by acting as toxicants. Excess nutrients in freshwater streams stimulate growth of algae that can impair stream communities by causing oxygen depletion and through other pathways. Because excess nutrients in surface waters are well known as stressors that impair aquatic life and impact other uses, the U.S. Environmental Protection Agency (EPA) is requiring CWA agencies throughout the U.S. to establish criteria for nutrients. The Academic Advisory Committee (AAC) to the Virginia Department of Environmental Quality (DEQ) has recommended a screening approach for nutrient criteria in Virginia as an alternative to single fixed-concentration numeric criteria as is commonly employed for conventional toxicants. Here, we investigate the potential to establish nutrient criteria using a screening approach by seeking to derive screening parameters from analyses of Virginia DEQ water monitoring data.
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    A Screening-Value Approach to Nutrient Criteria Development for Freshwater Wadeable Streams in the Mountain and Piedmont Regions of Virginia: July 2008 – June 2009 Activities
    Zipper, Carl E.; Holtzman, Golde I.; Smock, Leonard A.; Yagow, Eugene R.; Benfield, Ernest F.; Bukaveckas, Paul A.; Lung, Wu-Seng; Shabman, Leonard A.; Stephenson, Stephen Kurt; Walker, Jane L.; Younos, Tamim M. (Virginia Water Resources Research Center, 2009)
    This report documents activities being conducted by the Water Quality Academic Advisory Committee (AAC) to Virginia Department of Environmental Quality (DEQ) in collaboration with Virginia DEQ for the purpose of developing nutrient criteria for wadeable, freshwater rivers and streams in the Mountain and Piedmont regions of Virginia. The Mountain region of Virginia is within the following Level III Ecoregions: Central Appalachians, Ridge and Valley, and Blue Ridge. The Piedmont region of Virginia is within the following Level III Ecoregions: Northern Piedmont and Piedmont.
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    Surface water quality trends in southwestern Virginia, 1970-1989. I, Seasonal Kendall analysis
    Zipper, Carl E.; Holtzman, Golde I.; Rheem, Sungsue, 1957-; Evanylo, Gregory K. (Virginia Water Resources Research Center, Virginia Polytechnic Institute and State University, 1992-02)
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    Testing for Changes in Trend in Water Quality Data
    Darken, Patrick Fitzgerald (Virginia Tech, 1999-09-03)
    Time Series of water quality variables typically possess many of several characteristics which complicate analysis. Of interest to researchers is often the trend over time of the water quality variable. However, sometimes water quality variable levels appear to increase or decrease monotonically for a period of time then switch direction after some intervention affects the factors which have a causal relationship with the level of the variable. Naturally, when analyzed for trend as a whole, these time series usually do not provide significant results. The problem of testing for a change in trend is addressed, and a method for perfoming this test based on a test of equivalence of two modified Kendall's Tau nonparametric correlation coefficients (neither necessarily equal to zero) is presented. The test is made valid for use with serially correlated data by use of a new bootstrap method titled the effective sample size bootstrap. Further issues involved in applying this test to water quality variables are also addressed.
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    Use of Escherichia coli for Microbial Source Tracking in a Mixed Use Watershed in Northern Virginia
    Wade, Timothy Rion (Virginia Tech, 2007-08-27)
    Prince William County, located in the rapidly developing Northern Virginia region, contains watersheds of mixed rural and urban/suburban uses. The project goal was to monitor and evaluate 21 stream locations, over 13 months, in the Occoquan Basin identified as impaired due to high E. coli densities. One site on each of eight streams, two sites on each of five streams, and three sites on the remaining stream were chosen for E. coli monitoring and microbial source tracking (MST). MST was performed using antibiotic resistance analysis (ARA) and fluorometric analysis. Escherichia coli was chosen as the indicator bacterium for purposes of comparison with previous project data and because a large body of evidence supports its use in freshwater systems. This study involved the only known MST project to incorporate data from five or more consecutive years. A total of 2854 environmental isolates were collected for analysis with ARA. These isolates were classified using a known source library (KSL) that consisted of 1003 unique resistance patterns. The resistance patterns of the KSL came from known fecal sources (human, pets, livestock, wildlife) in Prince William County. The KSL included isolates from previous years but was also updated with fresh isolates. The accuracy of the KSL was assessed through the use of a challenge set. The challenge set was classified against the KSL using discriminant analysis, verified by logistic regression. The average rate of correct classification was 93% for discriminant analysis and 96% for logistic regression. Results indicated that multiple sources of contamination were present at all sampling locations and that the major source(s) (human, pets, livestock, wildlife) of contamination were generally related to the land-use patterns and human activities at each location. Although no major or minor human signatures were found, all but two locations had either pet or livestock as the major signature, suggesting that human-related activities are playing a key role in contamination of the streams. Pets were the single most frequent major signature and wildlife was the most common minor signature. Fluorometric analysis was used to corroborate human-derived contamination. Fluorometric analysis has the ability to detect the presence of optical brighteners, synthetic compounds added to such household items as laundry detergent, dishwashing detergent and other washing agents. Despite having an undesirably high rate of false negatives (negative fluorometry readings not supported by ARA), fluorometric analysis maintained a low rate of false positives (positive fluorometry readings not supported by ARA) and continued to demonstrate its potential for source tracking. This project represented one of the first attempts at applying a full suite of performance criteria now recommended by the source tracking community for all MST projects. Such concepts as experimental design, toolbox approach, minimum detectable percentage, quantification, accuracy, specificity, robustness, range of applicability, and practicality were successfully incorporated. These performance criteria have in effect set a new standard to which all subsequent MST projects should adhere.