Use of Computed Tomography in Standing Position to Identify Guidelines for Screw Insertion in the Distal Phalanx of Horses: An Ex Vivo Study

Objectives— To compare the precision of radiography and computed tomography (CT) preoperatively in the standing position for identification of guidelines for screw insertion in the distal phalanx, and to identify whether standing CT might improve operative time compared with preoperative radiographic planning.
Study Design— Experimental ex vivo study.
Animals— Cadaveric equine thoracic limb pairs (n=10).
Methods— Insertion of a 4.5 mm cortex screw in lag fashion into an intact distal phalanx was evaluated in 2 groups (n=10) of cadaveric equine thoracic limbs. In 1 group, the site, direction, and length of the implant were determined by radiography, and in the other group, by CT. Accuracy of screw placement was verified by specimen dissection. Outcomes were (1) absence of penetration of the articular surface, the solar surface, or the semilunar canal (2) appropriate length and direction of the screw. Surgical time was also measured.
Results— No screw penetrated the articular surface, the solar surface, or the semilunar canal in either group. CT was more accurate to identify guidelines for screw insertion (U=23.50, P =.049). With CT, surgical time (mean, 7.7 minutes) was significantly shorter (U=0.000, P =.000) than with radiography (mean, 12.7 minutes).
Conclusion— Standing CT can be used to accurately determine anatomic landmarks for screw insertion in lag fashion in sagittal fractures of the distal phalanx.
Clinical Relevance— This study has a clear clinical relevance for improved internal fixation of sagittal fractures of the distal phalanx.     

Evaluating irrigation performance in a Mediterranean environment

Assessment of irrigation performance is a prerequisite for improving water use in the agricultural sector to respond to perceived water scarcity. Between 1996 and 2000, we conducted a comprehensive assessment of the performance of the Genil–Cabra irrigation scheme (GCIS) located in Andalusia, southern Spain. The area has about 7,000 ha of irrigated lands distributed in 843 parcels and devoted to a diverse crop mix, with cereals, sunflower, cotton, garlic and olive trees as principal crops. Irrigation is on demand from a pressurized system and hand-moved sprinkler irrigation is the most popular application method. Six performance indicators were used to assess the physical and economic performance of irrigation water use and management in the GCIS, using parcel water-use records and a simulation model. The model simulates the water-balance processes on every field and computes an optimal irrigation schedule, which is then checked against actual schedules. Among the performance indicators, the average irrigation water supply:demand ratio (the ratio of measured irrigation supply to the simulated optimum demand) varied among years from 0.45 to 0.64, indicating that the area is under deficit irrigation. When rainfall was included, the supply:demand ratio increased up to 0.87 in one year, although it was only 0.72 in the driest year, showing that farmers did not fully compensate for the low rainfall with sufficient irrigation water. Nevertheless, farmers in the area made an efficient use of rainfall, as indicated by the relatively high values (0.72–0.83) for the ratio of actual:attainable crop yields. Water productivity (WP) in the GCIS oscillated between 0.72 €/m³ and 1.99 €/m³ during the 4 years and averaged 1.42 €/m³ of water supplied for irrigation, while the irrigation water productivity (IWP) averaged 0.63 €/m³ for the period studied. WP is higher than IWP because WP includes production generated by rainfall, while IWP includes only the production generated by irrigation.Communicated by A. Kassam     

Differential expression of insulin‐like growth factor family members in immature cumulus–oocyte complexes from dairy cows with different genotypes

It has been evident the improvement of in vitro embryo production (IVEP) in dairy cows. Nevertheless, it is known that differences in the number and quality of oocytes between taurine and zebu females impact the efficiency and economic viability of IVEP. As the insulin‐like growth factor (IGF) system is related to follicular and oocyte development, we aimed to quantify mRNA abundance of IGF system members and pregnancy‐associated plasma protein‐A (PAPPA) in the cumulus–oocyte complexes (COCs) of Gir, 1/2 Holstein × 1/2 Gir and Holstein cows. Four pools of 30 immature COCs from Gir, 1/2 Holstein × 1/2 Gir and Holstein cows were obtained by ovum pickup (OPU), and the oocytes and cumulus cells (CC) were mechanically separated and stored at ?80°C. Total RNA was extracted from pools of 30 oocytes and their respective CC. Expression of target genes was assessed by real‐time RT‐PCR. In oocytes, the abundance of IGFR1 mRNA was higher (p < .05) in Gir cows compared with the other breeds. In contrast, in CC, mRNA encoding IGF2 (p < .05), IGFR2 (p < .05) and IGFBP4 (p < .01) was higher in Holstein donors compared with Gir and 1/2 Holstein × 1/2 Gir cows. Additionally, the abundance of PAPPA mRNA was higher in oocytes (p < .001) and CC (p < .01) in Gir and 1/2 Holstein × 1/2 Gir cows compared with the Holstein donors. In conclusion, the higher abundance of PAPPA mRNA in the oocytes and CC from Gir and cross‐breed donors combined with the low expression of IGFBP4 in the CC suggests an enhancement of the bioavailability of IGF‐free when compared with Holstein COCs.     

Restoring soil health to reduce irrigation demand and buffer the impacts of drought

Irrigation consumes three quarters of global water withdrawals each year. Strategies are needed to reduce irrigation water use, including increasing the efficiency of transfer methods and field application. Comprehensive restoration of soil health, specifically through organic matter amendments, can substantially reduce irrigation demand and increase crop yield. A program to restore severely degraded and desertified soils by incorporating coarse woodchips into the soil successfully increased rainfall capture and elevated soil moisture for several weeks between rainfall events at both Ningxia, north-west China and North Dakota, USA. With addition of fertilizer, woodchip incorporation further increased growth of wheat and alfalfa. Comprehensive soil health assessment of remnant grasslands was used to develop target reference soil profiles by which to guide restoration efforts. Given that most agricultural soils are degraded to some degree, soil health restoration can provide a powerful strategy toward achieving global food and water security.     

Homogeneous Linewidths in the Optical Spectrum of a Single Gallium Arsenide Quantum Dot

The homogeneous linewidths in the photoluminescence excitation spectrum of a single, naturally formed gallium arsenide (GaAs) quantum dot have been measured with high spatial and spectral resolution. The energies and linewidths of the homogeneous spectrum provide a new perspective on the dephasing dynamics of the exciton in a quantum-confined, solid-state system. The origins of the linewidths are discussed in terms of the dynamics of the exciton in zero dimensions, in particular, in terms of lifetime broadening through the emission or absorption of phonons and photons.     

Relative bioavailability of zinc in supplemental inorganic and organic sources for Nile tilapia Oreochromis niloticus fingerlings

A 90‐day feeding experiment was conducted with sex reversed Nile tilapia (Oreochromis niloticus) fingerlings fed purified or practical diets supplemented with different zinc sources to evaluate fish growth performance and zinc and iron retention in fish bones, fillets, liver, skin and eyes. The relative bioavailability value (RBV) of zinc in the supplemental sources tested was also calculated. Fish were fed with isonitrogenous and isoenergetic purified or practical diets supplemented with 150 mg Zn kg^?1, as zinc sulphate monohydrate (ZnSO₄), zinc oxide (ZnO) or zinc amino acid complex (Zn‐AA). The feeding trial was conducted in 30, 50 L aquaria where four 0.66 ± 0.01 g (mean ± SD) fingerlings were initially stocked. No significant differences were observed for any growth performance variables (P > 0.05). In practical diets, only ZnSO₄ and ZnO presented bone zinc retention similar to that for the standard zinc source. Zinc concentration in the bone of fish fed practical diet supplemented with Zn‐AA (171 ± 3.62 μg g^?1) was significantly lower than that verified for the practical diets supplemented with the standard zinc source (200 ± 17.7 μg g^?1) or with ZnSO₄ (204 ± 19.9 μg g^?1). Assuming the concentration of zinc in bones as the response criterion, the supplemental zinc RBV from ZnSO₄ (105%) was higher than the RBV for Zn‐AA (95.1%) or ZnO (94.9%). Iron concentration in the bones of animals fed the non‐zinc‐supplemented purified diet was significantly higher than that observed for purified diet supplemented with Zn‐AA (P < 0,05). The results of the present work allowed us to conclude that ZnSO₄ in relation to ZnO or Zn‐AA was the supplemental zinc source with higher zinc bioavailability to Nile tilapia.     

Evaluating irrigation performance in a Mediterranean environment

Characterizing water use and management in irrigated agriculture is a prerequisite for conserving agricultural water. We carried out a detailed analysis of irrigation performance by documenting the water use of about 840 parcels in an irrigation scheme (Genil–Cabra irrigation scheme; GCIS) located in Andalusia, southern Spain, from 1996 to 2000. Performance indicators based on the water balance detected two water-management strategies, depending on the crop: (1) cotton, garlic, maize and sugar beet had average ratios of measured irrigation supply to the simulated optimum demand (ARIS) ranging between 0.73 and 0.91 and (2) winter cereals, sunflower and olive had a much lower average ARIS (with a 4-year average of 0.28–0.39). We found a large variability in water usage among the management units in all cases. For instance, in cotton, even though the average ARIS was around 0.8, about 50% of the fields were not irrigated adequately (41% with deficit, 9% with excess). Water productivity (WP) in the GCIS was highest for the horticultural crops (garlic, olive; from 1.13 €/m³ to 6.52 €/m³) while it varied among the field crops, being lowest in maize (4-year average of 0.28 €/m³) and highest in sugar beet (4-year average of 1.04 €/m³). Large year-to-year variations in WP were observed in all crops, particularly in sunflower and garlic due either to fluctuating prices for garlic or to the effects of the 1998/1999 drought for sunflower. In fact, WP was lowest in all crops in that year, because seasonal irrigation depths were much higher than in the other 3 years. The combination of ARIS and other performance indicators allowed for determining performance levels and improvement measures. It was found that if more irrigation water is used in the GCIS, garlic and olive will be the crops that profit most from the additional supply. However, it was concluded that, given the wide range in water use and management encountered at the parcel level, improvement policies at the scheme level should always consider individual performance when designing measures for water conservation in irrigated agriculture.