An Agronomic Evaluation of Grazing Maize Combined with Companion Crops for Sheep in Northwestern KwaZulu-Natal, South Africa

Northwestern KwaZulu-Natal (KZN), in South Africa, is well known for its sheep production from natural rangeland in summer (October to May). During winter however, the nutritional value of the rangeland cannot maintain young growing sheep or pregnant and lactating ewes. With this in mind Lyle (1991) suggested the use of planted pastures for the winter. Crichton, Gertenbach & Henning (1998) and Esterhuizen & Niemand (1989) suggested maize crop residues for both cattle and sheep during winter, whereas Moore (1997) evaluated grazing maize (not harvested) for this purpose. He found that the protein content of the crop was inadequate and for this reason, protein rich companion crops were evaluated in this study

An Evaluation of Grazing Value of Maize and Companion Crops for Wintering Lactating Ewes

Northwestern KwaZulu-Natal (KZN), in South Africa, is well known for its sheep production from natural rangeland in summer (October to May). During winter, however, the nutritional value of the rangeland cannot maintain young growing sheep or pregnant and lactating ewes. With this in mind, Lyle (1991) suggested the use of planted pastures for the winter. Crichton et al. (1998) and Esterhuizen & Niemand (1989) suggested the use of maize crop residues for both cattle and sheep during winter, whereas Moore (1997) evaluated grazing (not harvested) maize for this purpose. He found that the crude protein content of the crop was inadequate and for this protein-rich companion crops were evaluated in this study

An Agronomic Evaluation of Grazing Maize Combined with Companion Crops for Sheep in Northwestern KwaZulu-Natal, South Africa

Northwestern KwaZulu-Natal (KZN), in South Africa, is well known for its sheep production from natural rangeland in summer (October to May). During winter however, the nutritional value of the rangeland cannot maintain young growing sheep or pregnant and lactating ewes. With this in mind Lyle (1991) suggested the use of planted pastures for the winter. Crichton, Gertenbach & Henning (1998) and Esterhuizen & Niemand (1989) suggested maize crop residues for both cattle and sheep during winter, whereas Moore (1997) evaluated grazing maize (not harvested) for this purpose. He found that the protein content of the crop was inadequate and for this reason, protein rich companion crops were evaluated in this study

Realistic modeling of leakage and intrusion flows through leak openings in pipes

The hydraulics of leakage and intrusion flows through leak openings in pipes is complicated by variations in the leak areas owing to changes in pressure. This paper argues that the pressure–area relationship can reasonably be assumed to be a linear function, and a modified orifice equation is proposed for more realistic modeling of leakage and intrusion flows. The properties of the modified orifice equation are explored for different classes of leak openings. The implications for the current practice of using a power equation to model leakage and intrusion flows are then investigated. A mathematical proof is proposed for an equation linking the parameters of the modified orifice and power equations using the concept of a dimensionless leakage number. The leakage exponent of a given leak opening is shown to generally not be constant with variations in pressure and to approach infinity when the leakage number approaches a value of minus one. Significant modeling errors may result if the power equation is extrapolated beyond its calibration pressure range or at high exponent values. It is concluded that the modified orifice equation and leakage number provide a more realistic description of leakage and intrusion flows, and it is recommended that this approach be adopted in modeling studies

Theoretical Modeling of the Thermal State of Accreting White Dwarfs Undergoing Classical Novae

White dwarfs experience a thermal renaissance when they receive mass from a stellar companion in a binary. For accretion rates < 10^-8 Msun/yr, the freshly accumulated hydrogen/helium envelope ignites in a thermally unstable manner that results in a classical novae (CN) outburst and ejection of material. We have undertaken a theoretical study of the impact of the accumulating envelope on the thermal state of the underlying white dwarf (WD). This has allowed us to find the equilibrium WD core temperatures (T_c), the classical nova ignition masses (M_ign) and the thermal luminosities for WDs accreting at rates of 10^-11 - 10^-8 Msun/yr. These accretion rates are most appropriate to WDs in cataclysmic variables (CVs) of P_orb <~ 7 hr, many of which accrete sporadically as dwarf novae. We have included ^3He in the accreted material at levels appropriate for CVs and find that it significantly modifies the CN ignition mass. We compare our results with several others from the CN literature and find that the inclusion of ^3He leads to lower M_ign for >~ 10^-10 Msun/yr, and that for below this the particular author's assumption concerning T_c, which we calculate consistently, is a determining factor. Initial comparisons of our CN ignition masses with measured ejected masses find reasonable agreement and point to ejection of material comparable to that accreted.Comment: 14 pages, 11 figures; uses emulateapj; accepted by the Astrophysical Journal; revised for clarity, added short discussion of diffusio

Phosphinogold(I) dithiocarbamate complexes : effect of the nature of phosphine ligand on anticancer properties

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Stream-field interactions in the magnetic accretor AO Piscium

UV spectra of the magnetic accretor AO Psc show absorption features for half the binary orbit. The absorption is unlike the wind-formed features often seen in similar stars. Instead, we attribute it to a fraction of the stream that overflows the impact with the accretion disk. Rapid velocity variations can be explained by changes in the trajectory of the stream depending on the orientation of the white-dwarf's magnetic field. Hence we are directly observing the interaction of an accretion stream with a rotating field. We compare this behavior to that seen in other intermediate polars and in SW Sex stars.Comment: Accepted for ApJ; 6 page