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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.
1

A Quantified Approach to Tomato Plant Growth Status for Greenhouse Production in a Semi Arid Climate

Renda da Costa, Paula MR January 2007 (has links)
Balancing plant growth between vegetative and reproductive status is crucial for producing high quality greenhouse tomatoes while maintaining high productivity in long crop production seasons. In the tomato industry, certain plant morphological characteristics are used to classify plant growth status as vegetative, reproductive or balanced. Each growth status has been associated with distinct greenhouse environments which reduce or enhance transpiration.The effect of different transpiration on vegetative, reproductive or balanced plant growth status as defined by a set of plant morphological characteristics was investigated. To validate the practical significance of such classification, growth status was quantified as the relationship between variations in morphological characteristics and the fresh weight distributed between reproductive and vegetative organs.Two electrical conductivity (EC) levels of the nutrient solution, high and standard EC, were combined with two potential transpiration environments, low and high potential transpiration. All treatment combinations were contrasted with a reference greenhouse environment similar to the industry standard.Electrical conductivity had the greatest effect on morphological characteristics which were reduced in size with high EC. For each EC level, the response decreased for increasing potential transpiration. Stem diameter had the greatest sensitivity to the different treatment combinations. For the standard EC and for the range of potential transpirations achieved, stem diameter varied within a relatively narrow range, close to the industry standard 'threshold' used to classify a balanced tomato plant. A reproductive plant growth status, as evaluated by a smaller value than this threshold, was observed only with high EC. No vegetative plants were produced within any potential transpiration or EC treatment combination.High EC decreased the cumulative total fresh weight production by the same magnitude for all potential transpirations. Potential transpiration had a minimal effect on the total fresh weight production or on its components. As a result, the fresh weight ratio between reproductive and vegetative plant organs was similar for most potential transpiration environments, regardless of variations in stem diameter. Therefore, within the range of potential transpiration environments achieved, the distinction between vegetative and reproductive growth status as an indicator of fresh weight distribution and fruit yields could not be quantitatively validated.
2

The association between environmental exposures and the physical growth status, bone growth status, and metabolic risk factors of children of Sudanese immigrant families living in the USA

Alasagheirin, Mohammad Hikmat 01 July 2013 (has links)
Objectives The purpose of this research was to describe the physical growth status, bone mineral content, areal bone mineral density, body composition, and metabolic risk level of children of Sudanese immigrant families, and to determine the relationship between these outcome measures and exposure to an adverse environment. Exposure was defined as the time spent in Sudan or neighboring countries and timing was defined as the age a child arrived in the USA. Two major modifying factors were considered; current nutritional status (food quality and food security) and current physical activity levels. Study Design and Methods This is a cross-sectional study conducted between July 2011 and April 2012. Subjects were recruited from the Iowa City, Iowa metropolitan area. The sample included 64 children between the ages of five and eighteen; 33 females and 31 males. Physical growth measures included weight, height, and BMI. Bone growth measures (body bone mineral content and areal bone mass density at the hip and spine) and body composition measures (lean mass, fat mass, and body fat percent) were measured using DXA. Metabolic risk factors included fasting blood glucose, low density lipoprotein (LDL), high density lipoprotein (HDL), total cholesterol, triglyceride, and C Reactive Protein (CRP) levels, and Homeostasis Model of Assessment Insulin Resistance (HOMA-IR). Physical activity was measured by self-report physical activity questionnaire for children and adolescents (modified PAQ-A and PAQ-C) and by direct measure using Omron Pedometers (HJ-720 IT). Other collected data included food quality, food security, food frequency, and pubertal development using a puberty developmental scale. Results The mean age for all children was 10.1 ± 3.3 years. More than half of the children (n=33, 51.6%) were born in the USA, 14 children (21.9%) were born in Sudan, and the other children were born in other countries. The majority of the children (63.6%) lived in low income households reporting annual income less than USD $19,000. Over one quarter (26.5%) of the children were overweight or obese as defined by BMI percentile and when categorized by BF%, 35.5% of the girls and 27.3% of the boys were identified as obese. Height stunting was noted with 4.7% severely stunted (more than 2 sd below the mean) and 9.4% moderately stunted (more than 1 sd below the mean). The mean Z score for FMI and LMI were -0.57 ± 1.51 and 0.49 ± 0.75, respectively, and neither was normally distributed. Around half of the children had FMIZ (53.1%) and LMIZ (47%) scores more than 1 SD below the mean. Median Z scores for all bone measures were negative; BMC, -0.71, hip aBMD, -0.53, and Spine aBMD, -0.13. Around one-third of the children fell more than 1sd below the mean for BMC (38%) and hip aBMD (33%). Metabolic risk factors were elevated in some subjects; high total cholesterol, 23.4%; high triglycerides, 32.8%; low HDL, 19%; high HOMA-IR and CRP levels, 15.6 %. Forty percent of participating families reported some level of food insecurity, and 31% reported skipping or cutting the size of meals due to inadequate food supplies. Both self-reported questionnaires and data collected from pedometers showed that the majority of study participants were inactive, Wednesday & Thursday were identified as the most active days with activity levels of 52.6% and 50.9%, respectively, and 40% of the study subjects were inactive on weekends. More than half (56.9%) of the subjects reported watching TV more than two hours per day. Children born in the USA had higher rates of height and weight stunting and obesity as compared to children born outside the USA (24%, 37.5%, 32.26%; 3.12%, 25%, 21.21%, respectively). Children born in the USA had lower Z scores in all bone and body composition measures. Using GEE analysis, longer residence in Sudan was associated with lower WAZ scores (β =-0.16, p= 0.07), and lower LMIZ scores (β =-0.05, p= 0.06). Children with longer residence in Sudan or neighboring countries had higher LDL and HOMA-IR levels (β =2.997, p= 0.0005), and (β =0.03, p= 0.08). Adjusting for gender, girls who spent more time in Sudan had higher triglyceride and CRP levels β =11.9, p=0.027) and (β =0.5, p=0.03), respectively. Children who were older when they entered the USA had higher HAZ scores (β =0.06, p=0.05). Adjusting for gender, Girls who arrived in the USA at a younger age had lower WAZ scores (β =-0.42, p=0.01), while girls who entered the USA at an older age had higher HOMA-IR, triglyceride, and CRP levels (β =0.29, p=0.005), (β =0.14, p= 0.05) and (β =0.5, p=0.05), respectively. Adjusting for number of years spent in the USA and physical activity levels, longer residence in Sudan was associated with poorer LMIZ (β =-0.06, p=0.001) and hip aBMD Z scores (β =0.11, p= 0.01). In addition, children who arrived in the USA at a younger age had higher height for age Z scores (β=0.094, p=0.005) and lower LMIZ scores (β =-0.09, p=0.04), respectively. Conclusion Sudanese children in the Iowa City metropolitan area, particularly those born in the USA, have low Z scores for physical growth, bone growth, and body composition measures. A significant percent of the children had high triglycerides and total cholesterol levels. The majority of Sudanese children were physically inactive and food insecurity was common.
3

The Relationship of School Size and Socioeconomic Status to Middle Grades Growth Status on End of Grade Tests in North Carolina.

Peoples, Andrew 03 May 2008 (has links) (PDF)
The purpose of this quantitative study was to compare student achievement, as assessed by the ABC (Accountability, Basics, Local Control) end of grade tests, of students in different sized schools and of different socioeconomic backgrounds. The population consisted of 379 middle schools in North Carolina. Data were gathered from the 2006-2007 school year. Several t-tests for independent samples, analyses of variance, and chi square analyses were used to identify relationships between variables. The measures of growth used were the change ratio, which is used to determine high growth status and mean growth, which is used to determine expected growth or no recognition status. No recognition is the designation given to those schools that do not meet expected growth. The study showed no significant relationship between school size and academic growth status. Similarly, there was no significant difference in the observed proportions and the hypothesized proportions of different sized schools in terms of academic growth status. There was a significant relationship between socioeconomic status and academic growth status; high socioeconomic status schools had higher change ratios and higher mean growth than did low socioeconomic status schools. The study showed a significant difference in the observed and hypothesized proportions of the growth levels; high socioeconomic status schools had more schools designated high growth than no recognition and low socioeconomic status schools had more schools designated no recognition than high growth. The results of this study indicated that as educators in North Carolina continue to focus on achievement levels of all students, particular attention should be paid to those schools with higher percentages of students receiving free or reduced price meals. To narrow the academic gap between students in high and low socioeconomic status schools, attention should be given to the particular needs and traits of children from high poverty backgrounds. Educational practices that recognize and remove the barriers associated with those needs should be implemented. Regardless of socioeconomic status, educational methods in all schools should reflect current research of best practices for increasing all students' achievement.
4

Differences between Nutrition Knowledge of Mothers of Preschoolers and the Growth Status and Dietary Intake of the Preschoolers.

Patel, Priyadarshni 15 May 2020 (has links)
No description available.

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