Yehia Badr

Taro [Colocasia esculenta (L.) Schott] is an underutilised crop in sub-Saharan Africa due to lack of agronomic research on it. There is no information describing water-use and drought tolerance of local taro landraces. Therefore, the objective of this study was to evaluate growth, yield and water-use of three South African landraces of taro under varying water regimes. Three taro landraces [Dumbe Lomfula (DL), KwaNgwanase (KW) and Umbumbulu (UM)] were planted in a rainshelter (14, October, 2010 and 8, September, 2011) at Roodeplaat, Pretoria, South Africa. Three levels of irrigation [30%, 60% and 100% crop water requirement (ETa)] were applied three times a week using drip irrigation. Emergence, plant height, leaf number, leaf area index (LAI) and stomatal conductance were measured in situ. Root length, fresh and dry mass were obtained by destructive sampling. Yield, yield components and water-use efficiency were determined at harvest. Taro landraces showed slow and uneven emergence. Stomatal conductance was respectively, 4% and 23% lower at 60% and 30% \{ETa\} relative to 100% ETa. Such a decline was clearer in the \{UM\} landrace, suggesting greater stomatal regulation in the \{UM\} landrace compared with \{KW\} and \{DL\} landraces. Plant growth parameters (plant height, leaf number and LAI) were shown to decrease by between 5% and 19% at 60% and 30% ETa, respectively, evapotranspiration relative to 100% ETa. The \{KW\} and \{DL\} landraces were shown to decrease the most while the \{UM\} landrace had moderate reductions in growth. Taro yield was 15% and 46% higher at optimum irrigation relative to 60% \{ETa\} and 30% ETa, respectively. Water-use efficiency was relatively unchanged (0.22–0.24 kg m−3) across varying water regimes. On average, the \{UM\} landrace had 113% higher \{WUE\} than the \{KW\} landrace. These findings can be used to differentiate the landraces on the basis of potential drought tolerance.

Abstract Felsic magmatism associated with ocean–ocean and ocean–continent subduction processes provide important evidence for distinct episodes of crust-generation and continental lithospheric evolution. Rhyolites constitute an integral component of the tholeiitic to calc-alkaline basalt–andesite–dacite–rhyolite (BADR) association and contribute to crustal growth processes at convergent plate margins. The evolution of the Dharwar Craton of southern peninsular India during Meso- to Neoarchean times was marked by extensive development of greenstone belts. These granite-greenstone terranes have distinct volcano-sedimentary associations consistent with their geodynamic setting. The present study deals with geochemistry of rhyolites from the Chitradurga-Shimoga greenstone belts of western (WDC) and the Gadwal-Kadiri greenstone belts of eastern (EDC) sectors of Dharwar Craton to compare and evaluate their petrogenesis and geodynamic setting and their control on the continental lithospheric evolution of the Dharwar Craton. At a similar range of SiO2, Al2O3, Fe2O3, the rhyolites of \{WDC\} are more potassic, whereas the \{EDC\} rhyolites are more sodic and less magnesian with slight increase in TiO2. Minor increase in MgO content of \{WDC\} rhyolites reflects their ferromagnesian trace elements which are comparatively lower in the rhyolites of EDC. The relative enrichment in \{LILE\} (K, Rb) and depletion in \{HFSE\} (Nb, Ta, Zr, Hf) marked by negative Nb–Ta, Zr–Hf and Ti anomalies endorse the convergent margin processes for the generation of rhyolites of both the sectors of Dharwar Craton. The high silica potassic rhyolites of Shimoga and Chitradurga greenstone belts of \{WDC\} showing prominent negative Eu and Ti anomalies, flat \{HREE\} patterns correspond to Type 3 rhyolites and clearly point towards their generation and emplacement in an active continental margin environment. The geochemical characteristics of Gadwal and Kadiri rhyolites from eastern Dharwar Craton marked by aluminous compositions with low and fractionated \{HREE\} patterns and minor negative Eu anomalies are in conformity with Type 1 rhyolites and suggest that they were erupted in an intraoceanic island arc system. The overall geochemical systematics of the rhyolites from both the sectors of Dharwar Craton suggest a change in the geodynamic conditions from intraoceanic island arc of eastern Dharwar Craton and an active continental margin of western Dharwar marked by ocean–ocean subduction and migration of oceanic arc towards a continent followed by arc-continent collision that contributed for the evolution of continental lithosphere in the Dharwar Craton.

Abstract The aims of this study were to obtain the incidence of infertility, to examine the causes of infertility and to explore risk factors for impaired fecundity in a rural region of northern China using a prospective follow-up design. A total of 2151 newly married couples planning to become pregnant within the next 12 months were enrolled between 2009 and 2012 from two counties of Shanxi Province in northern China. Couples were followed up for at least 1 year or until a clinical pregnancy occurred. Information about clinical pregnancy was obtained. The 12-month and 24-month infertility rates were 13.6% (95% \{CI\} 11.9 to 15.3) and 8.5% (95% \{CI\} 6.7 to 10.3), respectively. About 63% of women became pregnant within 6 months of follow up, and 86% did so within 12 months of follow up. The main causes of female infertility were ovulation disorders, fallopian tube problems and polycystic ovary syndrome. The primary cause of male infertility was sperm quality problems. Couples who used coal as cooking fuel, women with a higher body mass index, women with long-term health problems, and men who had married at later ages were more likely to have delayed pregnancies.

Abstract The ChahJam–Biarjmand complex (CJBC), flanked by the Alborz Mountains in the north and the Lut–Tabas block to the south, is part of Central Iranian block, where the oldest continental crust of Iran is found. This complex contains granitic to tonalitic orthogneissic rocks (old plutons) and associated metasediments, amphibolites and paragneisses. Metamorphosed granitic and granodioritic dikes intrude orthogneisses as well as metasediments and are abundant close to the plutons (orthogneissic rocks). Based on the results of bulk rock trace and rare earth elements, the orthogneissic rocks are inferred to have crystallized from subduction-related melts. Amphibolites also have subduction-related signatures and are inferred to have formed both as metamorphosed volcanoclastic sediments and as attenuated basic dikes. The presence of para-amphibolites associated with paragneisses and metasediments (mica schists) could represent a sedimentary basin filled with magmatic arc erosional products. U–Pb zircon dating of the ChahJam–Biarjmand rocks yielded 238U/206Pb crystallization ages of ca. 550 to 530 Ma (Ediacaran–early Cambrian). Sr–Nd isotope systematics on whole rocks (εNd(t) = − 2.2 to − 5.5) and zircon Hf isotope results indicate that \{CJBC\} Cadomian granitic rocks contain older, possible Mesoproterozoic, continental crust in their source. The ChahJam–Biarjmand granitic–tonalitic gneissic rocks are coeval with other similar-aged metagranites and gneisses within Iranian basement exposed in Central Iran, the Sanandaj–Sirjan Zone and the Alborz Mountains, as well as in the Tauride–Anatolide platform in western Anatolia and in \{NW\} Turkey. All these dispersed Cadomian basement rocks are interpreted to show fragments of Neoproterozoic–early Cambrian continental arcs bordering the northern active margin of Gondwana.

Abstract The ChahJam–Biarjmand complex (CJBC), flanked by the Alborz Mountains in the north and the Lut–Tabas block to the south, is part of Central Iranian block, where the oldest continental crust of Iran is found. This complex contains granitic to tonalitic orthogneissic rocks (old plutons) and associated metasediments, amphibolites and paragneisses. Metamorphosed granitic and granodioritic dikes intrude orthogneisses as well as metasediments and are abundant close to the plutons (orthogneissic rocks). Based on the results of bulk rock trace and rare earth elements, the orthogneissic rocks are inferred to have crystallized from subduction-related melts. Amphibolites also have subduction-related signatures and are inferred to have formed both as metamorphosed volcanoclastic sediments and as attenuated basic dikes. The presence of para-amphibolites associated with paragneisses and metasediments (mica schists) could represent a sedimentary basin filled with magmatic arc erosional products. U–Pb zircon dating of the ChahJam–Biarjmand rocks yielded 238U/206Pb crystallization ages of ca. 550 to 530 Ma (Ediacaran–early Cambrian). Sr–Nd isotope systematics on whole rocks (εNd(t) = − 2.2 to − 5.5) and zircon Hf isotope results indicate that \{CJBC\} Cadomian granitic rocks contain older, possible Mesoproterozoic, continental crust in their source. The ChahJam–Biarjmand granitic–tonalitic gneissic rocks are coeval with other similar-aged metagranites and gneisses within Iranian basement exposed in Central Iran, the Sanandaj–Sirjan Zone and the Alborz Mountains, as well as in the Tauride–Anatolide platform in western Anatolia and in \{NW\} Turkey. All these dispersed Cadomian basement rocks are interpreted to show fragments of Neoproterozoic–early Cambrian continental arcs bordering the northern active margin of Gondwana.

Abstract In laser beam machining with oxygen gas, striations are formed on the cut surface due to the cyclic oxidization reaction, which is affected by the cutting conditions and the thermal properties of the workpiece. The formation of striations causes an increase in surface roughness. In order to reduce the surface roughness, we propose controlling the formation of striations by utilizing multi-DOF oscillation of the focus position of the laser. In this paper, we construct a laser machining system in which positioning control of the focus position is achieved by driving the focal lens. The effect of orbital oscillation of the laser focus position parallel to the top surface of the workpiece and vertical oscillation perpendicular to this surface on the formation of striations was evaluated by performing laser cutting tests on thick mild steel plates. The experimental results show that control of the formation of striations can be realized by choosing the appropriate oscillation conditions. The surface roughness with oscillation was less than half that without oscillation.