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1,350 results on '"Van Zyl, J."'

103. The trajectory of general movements from birth until 12 - 14 weeks corrected age in very lowbirthweight and extremely low-birthweight infants born preterm.

Author

Krynauw, R., du Preez, J. C. F., van Zyl, J. I., and Burger, M.

Subjects
PREMATURE infants, MIDDLE-income countries, PREDICTIVE validity, AGE, BIRTH weight
Abstract

Background. General movement assessment (GMA) is an assessment tool with high predictive validity for neurodevelopmental outcomes in preterm infants. Information available describing the trajectory of general movements (GMs) in high-risk preterm-born infants and the use thereof in low- and middle-income countries is limited. Objective. To describe the trajectories of GMs from birth until 12 - 14 weeks' corrected age, and determine the association of known perinatal risk factors on GM trajectories in very low-birthweight and extremely low-birthweight preterm infants. Methods. This was a longitudinal, prospective cohort study with 119 preterm infants born at <33 weeks' gestation and with a birthweight <1 500 g. GMs were recorded at four key age periods: 1 - 2 weeks after birth to 33 weeks post menstrual age (PMA); 34 - 37 weeks PMA; term equivalent age (TEA); and 12 - 14 weeks corrected age. Detailed perinatal data were collected. Results. A total of 300 GMAs were conducted, 157 during the preterm age, 55 during TEA and 88 at 12 - 14 weeks corrected age. At <33 weeks PMA, 96% of GMs were abnormal and 4% normal. At 34 - 37 weeks PMA, 89% of GMs were abnormal and 11% normal. All GMs recorded at term equivalent age were abnormal. At 12 - 14 weeks corrected age, 7% of GMs were abnormal and 93% normal. Conclusion. GMs were predominantly abnormal prior to term with a significant decrease in abnormality at 12 - 14 weeks corrected age. Lower birthweight and lower PMA were associated with increased odds for abnormal GMs. In a resource-constrained environment, observing GMs at 12 - 14 weeks corrected age (during the fidgety period) is a time- and cost-effective method to determine the risk for adverse neurodevelopment. [ABSTRACT FROM AUTHOR]

Published
2022
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105. (169) Incidence and Predictors of Vasoplegia after Heart Transplantation: Results from the International PGD Consortium

Author

Han, J., Moayedi, Y., Truby, L., Foroutan, F., Bofarull, J. Guzman, Saha, S., Angleitner, P., Sabatino, M., Henricksen, E., Luikart, H., van Zyl, J., Tremblay-Gravel, M., Noly, P., Segovia-Cubero, J., Alesina, E. Ródenas, Potena, L., Takeda, K., Felius, J., Clarke, B., DeVore, A., Kim, G., Miller, R., Zuckermann, A., Farr, M., Crespo-Leiro, M., Hall, S., Torres, M. Farrero, Fan, C., Ross, H., Khush, K., and Chih, S.

Published
2023
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109. Deriving Soil Moisture with the Combined L-Band Radar and Radiometer Measurements

Author

Shi, Jiancheng, Chen, K. S, Tsang, L, Jackson, T, Njoku, E, Van Zyl, J, O'Neill, P. O, Entekhabi, D, Johnson, J, and Moghaddam, M

Subjects
Earth Resources And Remote Sensing
Abstract

In this study, we develop a combined active/passive technique to estimate surface soil moisture with the focus on the short vegetated surfaces. We first simulated a database for both active and passive signals under SMAP s sensor configurations using the radiative transfer model with a wide range of conditions for surface soil moisture, roughness and vegetation properties that we considered as the random orientated disks and cylinders. Using this database, we developed 1) the techniques to estimate surface backscattering and emission components and 2) the technique to estimate soil moisture with the estimated surface backscattering and emission components. We will demonstrate these techniques with the model simulated data and its validation with the airborne PALS image data from the soil moisture SGP 99 and SMEX 02 experiments.

Published
2011

110. The palatability of a green seaweed, Ulva lactuca, for sheep.

Author

Sutherland, B., Van Zyl, J. H. C., and Cruywagen, C. W.

Subjects
*SHEEP, *ULVA, *MARINE algae, *DRINKING (Physiology), *FEED utilization efficiency
Abstract

The article focuses on the significance of feed intake in animal productivity, emphasizing its impact on energy use efficiency and production rates. Topics include evaluating palatability as a crucial factor influenced by sensory perception and physical attributes of the feed, with specific focus on Ulva lactuca, a green seaweed, as a potential alternative feed source for ruminants due to its nutritional composition comparable to medium-quality forage and sustainable production advantages.

Published
2024

115. Influence of planting techniques and maturity group on soya bean (Glycine max L.) yield in different agro-ecologies

Author

Van Zyl, J. P., Ceronio, G. M., Van Zyl, J. P., and Ceronio, G. M.

Abstract

In South Africa soya beans are mainly produced in the Mpumalanga and Free State provinces, while within the Free State, production is concentrated in the North Eastern Free State. It is widely known that soya bean yield is influenced by agronomic inputs such as, maturity group, plant density, row width as well as planting date. Extensive research was done globally on these agronomic inputs. However, very little, if any research was done in South Africa, especially in the North Eastern Free State. In an attempt to evaluate the yield response to different maturity groups, plant densities, row widths and planting dates, three trials were conducted on farmer’s fields over two seasons (2016/17 and 2017/18) in the North Eastern Free State at three agro-ecologically different experimental sites. The same maturity groups (MG 4.5, MG 5 and MG 6) was planted at different plant densities, row widths and planting dates at each trial. Phenological development, plant height, pod clearance, number of pods per plant, number of seeds per pod, hundred-seed weight and grain yield were measured. At trial 1 the three maturity groups were planted at four plant densities (200 000, 300 000, 400 000 and 500 000 plants ha-1), one row width (0.76 m) and one planting date. Maturity group had the greatest effect on phenological development, plant height, pod clearance, hundred-seed weight, and grain yield. Plant density had the greatest effect on plant height, number of pods per plant, while also affecting yield only during the 2016/17 season. At trial 2 the three maturity groups were planted at four plant densities (150 000, 200 000, 300 000 and 400 000 plants ha-1), two row widths (0.38 m and 0.76 m) and one planting date. Similar to trial 1, maturity group had the greatest effect on phenological development, plant height, pod clearance, hundred-seed weight and grain yield. Plant density had the greatest effect on plant height and number of pods per plant, while also affecting grain yield sli, Protein Research Foundation (PRF), Oilseeds Advisory Committee (OAC), University of the Free State (UFS)

Published
2020

120. Estimation of Soil Moisture with L-band Multi-polarization Radar

Author

Shi, J, Chen, K. S, Kim, Chung-Li Y, Van Zyl, J. J, Njoku, E, Sun, G, O'Neill, P, Jackson, T, and Entekhabi, D

Subjects
Earth Resources And Remote Sensing
Abstract

Through analyses of the model simulated data-base, we developed a technique to estimate surface soil moisture under HYDROS radar sensor (L-band multi-polarizations and 40deg incidence) configuration. This technique includes two steps. First, it decomposes the total backscattering signals into two components - the surface scattering components (the bare surface backscattering signals attenuated by the overlaying vegetation layer) and the sum of the direct volume scattering components and surface-volume interaction components at different polarizations. From the model simulated data-base, our decomposition technique works quit well in estimation of the surface scattering components with RMSEs of 0.12,0.25, and 0.55 dB for VV, HH, and VH polarizations, respectively. Then, we use the decomposed surface backscattering signals to estimate the soil moisture and the combined surface roughness and vegetation attenuation correction factors with all three polarizations.

Published
2004

121. The unique radar properties of silicic lava domes

Author

Plaunt, J J, Anderson, S. W, Crown, D. A, Stofan, E. R, and van Zyl, J. J

Subjects
Earth Resources And Remote Sensing
Abstract

Silicic lava domes exhibit distinct morphologic characteristics at scales of centimeters to kilometers. Multiparameter radar observations capture the unique geometric signatures of silicic domes in a set of radar scattering properties that are unlike any other natural geologic surfaces.

Published
2004

126. Effect of reduced concentrate supplementation rates on the production parameters of pasture-based lactating Jersey cows in winter.

Author

de Beer, J., Steyn, L., van Zyl, J. H. C., and Kleynhans, T

Subjects
JERSEY cattle, LACTATION in cattle, LACTATION, DIETARY supplements, ANIMAL herds, FAT content of milk, MASTITIS, DIETARY carbohydrates
Abstract

The article focuses on the effect of reduced concentrate supplementation on the production parameters of pasture-based Jersey cows in winter. Topics include the use and level of concentrate supplementation, milk-to-feed ratios, and results and discussions related to the study. It mentions that the study showed that yield can be maintained even at low supplementation levels, and treatment did not have an effect on milk fat or protein content.

Published
2023

135. Overview of Polarimetric Interferometry

Author

Kim, Y and van Zyl, J

Abstract

SAR interferometry has enabled two important science applications: surface change detection and topographic mapping.

Published
2000

142. Achievements in the Development of Space-borne Imaging Radar

Author

Kim, Y, Stuhr, F, van Zyl, J, Rosen, P, Freeman, A, Johnson, W, Jordan, R, Caro, E, and Shen, Y

Subjects
Communications And Radar
Abstract

This article describes past and current achievements in the development of space-borne imaging radar technology and discusses possibilities for the future. The article focuses on space-borne capabilities for civil and scientific purposes.

Published
1999

143. First Results From the GeoSAR Mapping Instrument

Author

Yang, M, Werner, C, van Zyl, J, Treuhaft, B, Thompson, T, Somoano, R, Siqueira, P, Rodriguez, E, Okonek, J, Moller, D, Michel, T, Le, C, Kroger, P, Hamilton, G, Freedman, A, Chapin, E, Brown, W, Berkun, A, Wheeler, K, and Hensley, S

Abstract

UNKNOWN

Published
1999

144. First Results From the GeoSAR Mapping Instrument

Author

Hensley, S, Wheeler, K, Berkun, A, Brown, W, Chapin, E, Freedman, A, Hamilton, G, Kroger, P, Le, C, Michel, T, Moller, D, Okonek, J, Rodriguez, E, Siqueira, P, Somoano, R, Thompson, T, Treuhaft, B, van Zyl, J, Werner, C, and Yang, M

Published
1999

149. Single Pass Polarimetric SAR Interferometry

Author

van Zyl, J and Kim, Y

Abstract

During the past ten years, the NASA/JPL AIRSAR system has produced polarimetric and interferometric SAR data. SAR polarimetry is useful for characterizing scattering mechanisms while SAR interferometry yields high resolution topographic maps.

Published
1998

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