Carbon dioxide emission in relation with irrigation and organic amendments from a sweet corn field.

Soil moisture and organic matter level affects soil respiration and microbial activities, which in turn impact greenhouse gas (GHG) emissions. This study was conducted to evaluate the effect of irrigation levels (75% [deficit], 100% [full], and 125% [excess] of reference crop evapotranspiration requirements), and organic amendments (OA) type (chicken manure [CM] and bone meal [BM]) and OA application rates (0,168, 336 and 672 kg total N ha-1) on (i) soil physical properties (bulk density, organic matter content and soil moisture content) and (ii) soil carbon dioxide (CO2) emissions from a highly weathered tropical Hawai'ian soil. Carbon dioxide readings were consistently taken once or twice a week for the duration of the cropping season. A drip irrigation system was used to apply the appropriate amount of irrigation water to the treatment plots. Treatments were randomly selected and corresponding organic amendments were manually incorporated into the soil. Plots were cultivated with sweet corn (Zea mays 'SS-16'). Soil moisture content within and below the rootzone was monitored using a TDR 300 soil moisture sensor (Spectrum Technologies, Inc., Plainfield, IL, USA) connected with 12 cm long prongs. Soil bulk density and organic matter content were determined at the end of the cropping season. Analysis of variance results revealed that OA type, rate, and their interaction had significant effect on soil CO2 flux (P < 0.05). Among the OA rates, all CM mostly resulted in significantly higher soil CO2 fluxes compared to BM and control treatment (p < 0.05). The two highest rates of BM treatment were not significantly different from the control with regard to soil CO2 flux. In addition, organic amendments affected soil moisture dynamics during the crop growing season and organic matter content measured after the crop harvest. While additional studies are needed to further investigate the effect of irrigation levels on soil CO2 flux, it is recommended that in order to minimize soil CO2 emissions, BM soil amendments could be a potential option to reduce soil CO2 fluxes from agricultural fields similar to the one used in this study.

Status of vitamins A and E in schoolchildren in the centre west of Tunisia: a population-based study.

OBJECTIVE: The present study was undertaken to assess the status of vitamins A and E (VA and VE, respectively) and their main determinants in Tunisian children. DESIGN: Cross-sectional population-based study. SETTING: Kasserine Governorate in the centre west of Tunisia. SUBJECTS: A total of 7407 children attending the first grade of elementary school were included. VA and VE were assessed by HPLC. RESULTS: The prevalence of moderate VA deficiency (VAD; <0·70 µmol/l) was 2·3 % and VE deficiency (VED; <6·97 µmol/l) was 5·4 %. Low status in VA (0·70-1·05 µmol/l) and VE (6·97-11·61 µmol/l) was observed in 17 % and 20·2 % of children, respectively. No child exhibited severe VA or VE deficiency (<0·35 and <2·32 µmol/l, respectively). The main predictors of VAD were advanced age (OR = 1·65; 95 % CI 1·13, 2·41; P = 0·05) and sickness within the past 2 weeks (OR = 1·51; 95 % CI 1·09, 2·09; P = 0·01). Predictors of VED were living in the peri-urban region (OR = 1·60; 95 % CI 1·28, 2·01; P < 0·001) and sickness within the past 2 weeks (OR = 0·75; 95 % CI 0·60, 0·94; P = 0·01). CONCLUSIONS: Moderate VAD and VED were uncommon in Tunisian children. However, low status in VA and/or VE remains frequent. A reinforcement of the national strategies for children's nutrition and health is needed, particularly in disadvantaged regions. Supplementation of VA and VE is not necessary in Tunisia, but food fortification may be beneficial.

Field calibrations of soil moisture sensors in a forested watershed.

Spatially variable soil properties influence the performance of soil water content monitoring sensors. The objectives of this research were to: (i) study the spatial variability of bulk density (ρ(b)), total porosity (θ(t)), clay content (CC), electrical conductivity (EC), and pH in the upper Makaha Valley watershed soils; (ii) explore the effect of variations in ρ(b) and θ(t) on soil water content dynamics, and (iii) establish field calibration equations for EC-20 (Decagon Devices, Inc), ML2x (Delta-T-Devices), and SM200 (Delta-T-Devices) sensors to mitigate the effect of soil spatial variability on their performance. The studied soil properties except pH varied significantly (P < 0.05) across the soil water content monitoring depths (20 and 80 cm) and six locations. There was a linear positive and a linear inverse correlation between the soil water content at sampling and ρ(b), and between the soil water content at sampling and θ(t), respectively. Values of laboratory measured actual θ(t) correlated (r = 0.75) with those estimated from the relationship θ(t) = 1 - ρ(b)/ρ(s), where ρ(s) is the particle density. Variations in the studied soil properties affected the performance of the default equations of the three tested sensors; they showed substantial under-estimations of the actual water content. The individual and the watershed-scale field calibrations were more accurate than their corresponding default calibrations. In conclusion, the sensors used in this study need site-specific calibrations in order to mitigate the effects of varying properties of the highly weathered tropical soils.

Measuring energy expenditure in community-dwelling older adults: are portable methods valid and acceptable?

The objective of this study was to assess the validity and acceptability of a handheld indirect calorimeter for measurement of resting energy expenditure in a sample of community-dwelling older adults. It was a measurement study involving 48 healthy community-dwelling older adults. Assessment of resting energy expenditure was performed in 48 healthy older adults under fasting conditions using the Europa Gas Exchange Monitor (GEM; ventilated hood indirect calorimeter, NutrEn Technology Ltd, Cheshire, UK) and the MedGem (handheld indirect calorimeter, HealtheTech Inc, Golden, CO). An eight-item self-administered survey was used to determine the acceptability of the two measurement devices. Bias and limits of agreement were calculated to determine the level of agreement between the two measurements. The Wilcoxon signed-ranks test was used to test for significant differences across items of the self-administered survey. Participants mean age was 80 years and mean body mass index (calculated as kg/m(2)) was 23. Mean (95% confidence interval) resting energy expenditure was 1,149 kcal/day (1,086, 1,194) and 1,489 kcal/day (1,386, 1,592) for the traditional and handheld indirect calorimeter, respectively; paired t test P<0.001. Mean bias and limits of agreement were 349 kcal (-270, 969) or 5 kcal/kg/day (-3.6, 13.2) with least products regression resulting in a slope of b(1)=1.9 (95% confidence interval 1.2, 2.7, P<0.05). The handheld indirect calorimeter was less acceptable to participants than the ventilated hood indirect calorimeter. Measurement of resting energy expenditure from the handheld indirect calorimeter used in this study is not acceptable for use in healthy older adults given the magnitude of the overestimate, the wide limits of agreement, the significant slope of the bias, and the discomfort experienced by the participants.

Retinol and Alpha-tocopherol in the Colostrum of Lactating Tunisian Women Delivering Prematurely: Associations with Maternal Characteristics.

BACKGROUND: This study aims to assess vitamin A and E concentrations in the premature colostrum of lactating Tunisian women and to identify maternal characteristics that may affect these concentrations. METHODS: Human colostrum was obtained from 105 mothers who gave birth prematurely in the Centre for Maternity and Neonatology of Tunis (Tunisia). Retinol and alpha-tocopherol were analyzed in the colostrum and in plasma by high-performance liquid chromatography. RESULTS: Retinol and alpha-tocopherol concentrations were 57.5 ± 50.1 µg/dL and 1222 ± 772 µg/dL in the colostrum, respectively, and 51.7 ± 20.0 µg/dL and 1351 ± 772 µg/dL in plasma, respectively. Concentrations of each vitamin in the colostrum were positively correlated with their respective concentrations in plasma (r = 0.415, p = 0.001 for retinol and r = 0.392, p = 0.003 for alpha-tocopherol). In multivariate analysis, colostrum vitamin A was associated with plasma vitamin A and preeclampsia, while colostrum vitamin E was associated with plasma vitamin E, gestational age, and preeclampsia. CONCLUSION: In Tunisian women, colostrum vitamin A and E levels are close to the average values reported in the literature. The levels are too low to cover the needs of very low birth weight (VLBW) infants, particularly in women with plasma vitamin deficiencies, preeclampsia, or very premature delivery. Given the undeniable beneficial effects of human colostrum, whenever feasible, VLBW infants should be fed colostrum. Infant vitamin A and E requirements should be met by milk fortification or supplementation.

Plasma arachidonic and docosahexaenoic acids in Tunisian very low birth weight infants: status and association with selected neonatal morbidities.

To study plasma arachidonic acid (AA) and docosahexaenoic acid (DHA) status in Tunisian very low birth weight (VLBW) infants and their association with selected neonatal morbidities. A total of 709 VLBW infants and 339 term infants were included. Plasma fatty acids were analyzed using capillary gas chromatography. VLBW infants had significantly (p < 0.001) lower plasma AA (9.44 ± 2.12 vs. 10.8 ± 2.10) and DHA (2.56 ± 0.89 vs. 3.46 ± 1.09) levels, but higher n-6:n-3 ratio (5.58 ± 1.22 vs. 5.17 ± 1.46) than term infants. In VLBW infants, plasma AA and DHA were related to gestational age (r = 0.156; p = 0.001 and r = 0.134; p = 0.003, respectively), birthweight (r = 0.242; p < 0.001 and r = 0.181; p < 0.001, respectively) and head circumference (r = 0.138; p = 0.005 and r = 0.108; p = 0.027, respectively). Infants with respiratory distress syndrome have decreased plasma AA and DHA and those with intraventricular hemorrhage have decreased plasma AA and n-6:n-3 ratio. Sepsis was associated with decreased DHA levels. Plasma long chain polyunsaturated fatty acids status is low in VLBW infants. These deficits may enhance the risk of common neonatal morbidities, rendering their prevention and correction greatly warranted.

Nutritional practice effectiveness to achieve adequate plasma vitamin A, E and D during the early postnatal life in Tunisian very low birth weight infants.

OBJECTIVE: To look at changes in plasma vitamin A, E and D concentrations during the early postnatal life and to study their link with growth and mortality in Tunisian very low birth weight (VLBW) infants. PATIENTS AND METHODS: A cohort of 607 VLBW infants had been followed from birth until hospital discharge or death. Blood was collected at birth, at time of maximal weight loss and at time of recovering birth weight. Retinol and α-tocopherol were analyzed using HPLC and 25 hydroxy vitamin D using radioimmunoassay. RESULTS: Vitamin A, D and E deficiencies were very common at birth (75.9%, 74.1% and 65.2%, respectively). The prevalence's have decreased throughout hospital stay, but remained high at time of recovering birth weight (59.4%, 31.2% and 28.8%, respectively). Vitamin A deficiency was associated with longer hospital stay [OR (95% CI), 1.66 (1.03-2.93)] and vitamin E deficiency was associated with increased neonatal mortality [1.44 (1.01-2.23)]. CONCLUSIONS: Current nutritional practices are ineffective to achieve adequate vitamins A, E and D status in Tunisian VLBW infants during the early postnatal life and should be revised. Further work is needed to establish recommended doses of vitamins supplements in these preterm infants.

VitaminA, E, and D deficiencies in tunisian very low birth weight neonates: prevalence and risk factors.

BACKGROUND: Preterm neonates are at high risk of vitamin deficiencies, which may expose them to increased morbidity and mortality. This study aimed to determine the prevalence and risk factors for vitamin A, E, and D deficiencies in Tunisian very low birth weight (VLBW) neonates. METHODS: A total of 607 VLBW and 300 term neonates were included in the study. Plasma vitamins A and E were assessed by high performance liquid chromatography and vitamin D was assessed by radioimmunoassay. RESULTS: Prevalence of vitamin A, E, and D deficiencies were dramatically elevated in VLBW neonates and were significantly higher than term neonates (75.9% vs. 63.3%; 71.3% vs. 55.5%; and 65.2% vs. 40.4%, respectively). In VLBW neonates, the prevalence of vitamin deficiencies was significantly higher in lower classes of gestational age and birth weight. Vitamin E deficiency was associated with pre-eclampsia [odds ratio (OR) (95% confidence interval, 95% CI), 1.56 (1.01-2.44); p < 0.01] and gestational diabetes [4.01 (1.05-17.0); p < 0.01]. Vitamin D deficiency was associated with twin pregnancy [OR (95% CI), 2.66 (1.33-5.35); p < 0.01] and pre-eclampsia [2.89 (1.36-6.40); p < 0.01]. CONCLUSION: Vitamin A, E, and D deficiencies are very common in Tunisian VLBW neonates and are associated with pre-eclampsia. Improved nutritional and health support for pregnant women and high dose vitamins A, E, and D supplementation in VLBW neonates are strongly required in Tunisia.